# Patent

## Title
Image forming apparatus having an air blowing device and an air exhaust device

## Abstract

An image forming apparatus includes an image forming section, an output section, a sheet transport unit, an air blowing device, and an air exhaust device. The image forming section forms a toner image. The sheet transport unit transports in a region above the image forming section a sheet onto which the toner image has been fixed. A first channel causes air to pass from a downstream side to an upstream side in a sheet transport direction, the air blowing device applies an airflow by using the first channel, a second channel causes the air to pass from the downstream side to the upstream side in the sheet transport direction, and the air exhaust device exhausts the air by using the second channel.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2015-143019 filed Jul. 17, 2015.
BACKGROUND
Technical Field
The present invention relates to an image forming apparatus.
SUMMARY
According to an aspect of the present invention, an image forming apparatus includes an image forming section, an output section, a sheet transport unit, an air blowing device, and an air exhaust device. The image forming section forms a toner image. The sheet transport unit transports in a region above the image forming section a sheet onto which the toner image has been fixed toward the output section in a substantially horizontal direction. In the image forming apparatus, a first channel having an air inlet is provided above the sheet being transported so as to cause air to pass from a downstream side to an upstream side in a sheet transport direction of the sheet transport unit, the air blowing device applies an airflow by using the first channel, a second channel having an air outlet is provided at a region above the image forming section and below the sheet so as to cause the air to pass from the downstream side to the upstream side in the sheet transport direction of the sheet transport unit, and the air exhaust device exhausts the air by using the second channel.



BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiment of the present invention will be described in detail based on the following figures, wherein:
FIG. 1A is a front view of the appearance of an image forming apparatus, and FIG. 1B is a front view of the image forming apparatus with a sheet transport section opened;
FIG. 2 is a schematic sectional view of an internal structure of the image forming apparatus;
FIG. 3A is a schematic longitudinal sectional view of a sheet transport path of a sheet transport device, and FIG. 3B is a schematic plan view of the sheet transport path;
FIG. 4 is a schematic sectional view of the sheet transport section illustrating passage of airflow in the sheet transport section; and
FIG. 5A is a schematic sectional view illustrating removal of a sheet in the sheet transport section, and FIG. 5B is a schematic sectional view illustrating replacement of the toner cartridges.



DETAILED DESCRIPTION
Next, an exemplary embodiment and a specific example of the present invention will be described in further detail below with reference to the drawings. It should be understood that the present invention is not limited to the exemplary embodiment and the specific example.
Furthermore, it should be noted that the drawings referred to in the following description are schematically illustrated and not to scale, and illustration of elements not required for the description is omitted as appropriate for ease of understanding.
(1) An Overall Structure and Operations of an Image Forming Apparatus 1
FIG. 1A is a front view of the appearance of an entirety of an image forming apparatus 1, FIG. 1B is a front view of the image forming apparatus 1 with a sheet transport section opened, and FIG. 2 is a schematic sectional view of an internal structure of the image forming apparatus 1.
An overall structure and operations of the image forming apparatus 1 are described below with reference to the drawings.
(1.1) The Overall Structure
The image forming apparatus 1 includes an image forming section 2 and an image reader 3. The image forming section 2 forms an image with an electrophotographic system. The image reader 3 reads a document and the like and is supported at a position above the image forming section 2 by an image reader support unit 4. A sheet transport device 70 is disposed between the image forming section 2 and the image reader 3. The sheet transport device 70 transports a sheet onto which an image has been fixed to an output section.
The image forming section 2 is structured as follows: a controlling device 10, sheet feed devices 20, photosensitive units 30, developing devices 40, a transfer device 50, and a fixing device 60 are disposed in a space formed by a housing F (not illustrated); the photosensitive units 30, the developing devices 40, and the transfer device 50 are shielded by a first front covering 1a; and toner cartridges T (Y), T (M), T (C), and T (K) and the sheet transport device 70 are shielded by a second front covering 1b serving as an opening/closing member at a position above the first front covering 1a. 
An operation and information unit 80 serving as a user interface is disposed on a front surface side of the image reader 3. A liquid crystal display panel, various types of buttons, a touch panel, and so forth are assembled together to form the operation and information unit 80. A user of the image forming apparatus 1 makes various types of settings and inputs instructions via the operation and information unit 80. The user of the image forming apparatus 1 is notified of various types of information via the liquid crystal display panel.
(1.2) The Image Forming Section
The controlling device 10 includes a controller 11, an image processing unit 12, a power source unit 13 and so forth. The controller 11 controls operations of the image forming apparatus 1. The controller 11 also controls operations of the image processing unit 12 and the power source unit 13. The power source unit 13 applies voltage to the photosensitive units 30, the developing devices 40, the transfer device 50, and so forth.
The image processing unit 12 converts print information received from an external information transmission apparatus (for example, a personal computer or the like) into image information for formation of a latent image and outputs drive signals to light exposure devices LH at preset timing.
The sheet feed devices 20 in which many sheets of paper P are stack are provided at a bottom portion of the image forming section 2. The sheets P each serve as a medium. In each of the sheet feed devices 20, the position of the sheets P in the width direction is determined by a regulating plate (not illustrated), and the sheets P are drawn forward (−X direction) one sheet after another from a top sheet P of a stack of the sheets P by a sheet drawing unit 22.
The sheets P drawn from the sheet drawing unit 22 are each transported to a nip in a registration roller pair 23.
The photosensitive units 30 are provided above (Z direction) the sheet feed devices 20 so as to be parallel to one another. The photosensitive units 30 each include a corresponding one of rotating photosensitive drums 31. Yellow (Y), magenta (M), cyan (C), and black (K) toner images are formed on the respective photosensitive drums 31 by the respective developing devices 40.
Yellow (Y), magenta (M), cyan (C), and black (K) toners are supplied from respective toner cartridges T (Y), T (M), T (C), and T (K) to the respective developing devices 40.
The toner images of the colors formed on the photosensitive drums 31 of the respective photosensitive units 30 are sequentially electrostatically transferred (first transfer) onto an intermediate transfer belt 51 of the transfer device 50. Thus, superposed toner images are formed by superposing the toner images of the colors. The superposed toner images on the intermediate transfer belt 51 are collectively transferred by a second transfer roller 52 onto the sheet P fed from the registration roller pair 23 and guided by a transport guide.
A fixing nip (fixing region) is formed between a pair of a heating module 61 and a pressure module 62 in pressure contact with each other in the fixing device 60.
The sheet P onto which the toner images have been collectively transferred by the transfer device 50 and have not yet been fixed is transported to the fixing nip of the fixing device 60 through a transport guide 53. In the fixing nip, the toner images are fixed due to the effects of the pressure and heat applied by the pair of the heating module 61 and the pressure module 62.
Bending of the sheet P onto which a fixed toner image has been formed is corrected by a curl correcting device 65. Then, the sheet P is fed from an output roller pair 63 to the sheet transport device 70. The sheet transport device 70 outputs the sheet P to a sheet output tray T1 while cooling the sheet P in a sheet transport path S with an airflow blown from an air blowing fan 81.
Furthermore, in order to invert the sheet P for duplex printing or in order to output the sheet P with an image recording side of the sheet P facing upward, a transport direction is switched to an upward direction (Z direction) by a switching gate G1.
As has been described, the image forming apparatus 1 has a C-shaped transport path, that is, a sheet transport path of the image forming apparatus 1 from the sheet feed devices 20 to the output roller pair 63 through the second transfer roller 52 has a C shape. This may minimize the length of the transport path of the sheet P and minimize first printout time (FPOT), which is a time period from the start of printing to output of the first sheet.
(2) The Structure and Operation of the Sheet Transport Section
FIG. 3A is a schematic longitudinal sectional view of the sheet transport section of the image forming apparatus 1, FIG. 3B is a schematic plan view of the sheet transport section, FIG. 4 is a schematic sectional view of the sheet transport section illustrating passage of air in the sheet transport device 70, FIG. 5A is a schematic sectional view illustrating removal of a sheet in the sheet transport device 70, and FIG. 5B is a schematic sectional view illustrating replacement of the toner cartridges.
The structure of the sheet transport section and cooling of the sheets are described below with reference to the drawings.
(2.1) The Structure of the Sheet Transport Section
As illustrated in FIG. 3A, the sheet transport section of the image forming apparatus 1 includes the sheet transport device 70, the air blowing fan 81, and an air exhaust fan 82.
The sheet transport device 70 includes an entrance roller pair 71, plural transport roller pairs 72, and an output roller pair 73. The entrance roller pair 71 receives the sheet P output via the output roller pair 63 of the image forming apparatus 1. The transport roller pairs 72 transport the sheet P received by this entrance roller pair 71 to a downstream side. The output roller pair 73 outputs the sheet P toward the sheet output tray T1.
The entrance roller pair 71, the transport roller pairs 72, and the output roller pair 73 each include a pair of rollers. The sheet transport path S is formed between one and another rollers of each of the pairs of rollers by an upper transport member 75 and a lower transport member 76 that guide the sheet P to the downstream side.
The sheet transport path S has a first transport path S1 and a second transport path S2. The first transport path S1 substantially horizontally extends from the entrance roller pair 71 to the downstream side. The second transport path S2 is continuous with the first transport path S1 and curved to the image forming section 2 side so as to be directed to the output roller pair 73.
A sheet guide member 77 is formed above the sheet transport path S. The sheet guide member 77 has a sheet guide surface 77a on its upper surface. The sheet guide surface 77a guides and temporarily holds the sheet P which is to be inverted for duplex printing. A lower surface 77b opposite to the sheet guide surface 77a faces an upper surface of the upper transport member 75, thereby defining a space R1.
The image-forming-apparatus 1 rear surface side (Y direction) of the space R1 is defined by a housing of an apparatus body and the image-forming-apparatus 1 front surface side (−Y direction) of the space R1 is defined by the second front covering 1b, thereby a first channel is formed.
A lower surface 76a of the lower transport member 76 faces a guide member 78 of the toner cartridges T (Y), T (M), T (C), and T (K), which are parts of the image forming section 2, so as to define a space R2.
The image-forming-apparatus 1 rear surface side (Y direction) of the space R2 is defined by the housing of the apparatus body and the image-forming-apparatus 1 front side (−Y direction) of the space R2 is defined by the second front covering 1b, thereby a second channel is formed.
The air blowing fan 81 is disposed on the downstream side of the sheet transport path S. More specifically, the air blowing fan 81 is disposed in a recess portion of the sheet transport path S formed by the second transport path S2 curved to the image forming section 2 side below the lower surface 77b opposite to the sheet guide surface 77a. Thus, air flowing in through an air inlet 1c is blown toward the first channel.
The air exhaust fan 82 is disposed on the upstream side of the sheet transport path S. The air exhaust fan 82 on one end side of the second channel sucks air in the second channel so as to exhaust the air to the fixing device 60 side through an air outlet 1d. 
As illustrated in FIG. 3B, the upper transport member 75 has many air blowing openings 75a. The air blowing openings 75a are open toward the sheet transport path S and have shapes elongated in the sheet transport direction.
As illustrated in FIG. 3A, the entrance roller pair 71, the transport roller pairs 72, and the output roller pair 73 include respective drive rollers 71a, 72a, and 73a disposed in the lower transport member 76. The drive rollers 71a, 72a, and 73a are paired with respective pinch rollers 71b, 72b, and 73b rotatably disposed in the upper transport member 75, thereby transporting the sheet P in the sheet transport path S. Furthermore, many air blowing openings 76b having elongated hole shapes are formed in a region of the lower transport member 76, the region forming a lower side surface of the second transport path S2. As a result, the first channel and the second channel communicate with each other through the air blowing openings 75a and the air blowing openings 76b in the second transport path S2 curved to the image forming section 2 side.
(2.2) Passage of Airflows
As illustrated in FIG. 4, the air blown from the air blowing fan 81 into the first channel flows into the first transport path S1 and the second transport path S2 through the air blowing openings 75a and passes along the upper surface of the sheet P to the upstream side in the sheet transport direction (see arrows F1 of FIG. 4).
Furthermore, the air that flows in through the air blowing openings 75a of the curved second transport path S2, flows out through the air blowing openings 76b of the curved second transport path S2, and flows into the second channel is sucked by the air exhaust fan 82 so as to pass through the second channel and to be exhausted to the fixing device 60 side through the air outlet 1d. 
The sheet P onto which the toner images have been fixed by the fixing device 60 is transported to the second transport path S2 while being cooled by the air that flows into the first channel, flows in through the air blowing openings 75a, and passes to the upstream side in the sheet transport direction in the first transport path S1.
The sheet P being transported through the second transport path S2 is cooled by the air flowing through the air blowing openings 75a while being curved to the image forming section 2 side. Thus, the sheet P to which an upward curl is given with respect to the sheet transport direction is output to the sheet output tray T1 so as to be stacked on the sheet output tray T1.
As has been described, the sheet transport device 70 has a sheet transport path S that substantially horizontally extends above the image forming section 2 from the output roller pair 63 to the output section. This may increase a time period during which the sheet P having been heated by the fixing device 60 is cooled in the sheet transport path S. Thus, the sheet P may be more effectively cooled.
The air to be exhausted from the air exhaust fan 82 passes in the second channel from the downstream side to the upstream side in the sheet transport direction (see an arrow F2 of FIG. 4) through the space R2 formed by the lower surface 76a of the lower transport member 76 and the guide member 78 of the toner cartridges T (Y), T (M), T (C), and T (K) that face the lower surface 76a, thereby suppressing diffusion of heat generated near the fixing device 60 toward the toner cartridges T (Y), T (M), T (C), and T (K) and cooling the toner cartridges T (Y), T (M), T (C), and T (K).
The air blown by the air blowing fan 81 from the downstream side to the upstream side in the sheet transport direction and the air exhausted by the air exhaust fan 82 are exhausted to the outside of the image forming apparatus 1 by an exhaust fan (not illustrated) that exhausts heated air near the fixing device 60 to the outside of the image forming apparatus 1.
As a result, the sheet P heated by the fixing device 60 is cooled in the sheet transport path S by the airflow applied from the air blowing fan 81. This suppresses heat transmission to the image reader 3 side and the toner cartridges T (Y), T (M), T (C), and T (K) side.
The heat generated near the fixing device 60 is intercepted by the airflow exhausted by the air exhaust fan 82, and accordingly, heat diffusion to the toner cartridges T (Y), T (M), T (C), and T (K) is suppressed.
As a result, an increase in temperature of the toner cartridges T (Y), T (M), T (C), and T (K) may be suppressed, and accordingly, stable image formation may be continuously performed.
(2.3) Opening of the Sheet Transport Path
As illustrated in FIG. 1A, the image forming apparatus 1 includes the first front covering 1a and the second front covering 1b. The first front covering 1a shields the photosensitive units 30, the developing devices 40, and the transfer device 50 at a position above the sheet feed devices 20. The photosensitive units 30, the developing devices 40, and the transfer device 50 are included in the image forming section 2. The second front covering 1b serving as the opening/closing member shields the toner cartridges T (Y), T (M), T (C), and T (K) and the sheet transport device 70 at a position above the first front covering 1a. 
In order to remove jammed paper from the sheet transport path S of the sheet transport device 70, or in order to replace any of the toner cartridges T (Y), T (M), T (C), and T (K), the second front covering 1b is opened as illustrated in FIG. 1B to perform the removal of the jammed paper or the replacement of the toner cartridges.
(2.3.1) Removal of Jammed Paper
As illustrated in FIG. 5A, when the second front covering 1b of the image forming apparatus 1 is opened, the sheet transport device 70 and the toner cartridges T (Y), T (M), T (C), and T (K) are exposed at the same time.
In this state, the upper transport member 75 of the sheet transport device 70 is moved upward to open the sheet transport path S, that is, to enlarge a gap between the upper transport member 75 and the lower transport member 76 (see an arrow R of FIG. 5A). Thus, jammed paper Pj in the sheet transport path S may be removed.
After the jammed paper Pj has been removed, the upper transport member 75 is moved downward to form the sheet transport path S.
A switch SW is provided between the second front covering 1b and a body of the image forming apparatus 1. The switch SW serving as a detector detects opening and closing of the second front covering 1b. When the second front covering 1b is closed after the jammed paper Pj has been removed, the closing of the second front covering 1b is detected by the switch SW.
(2.3.2) Replacement of the Toner Cartridges
As illustrated in FIG. 5B, when the second front covering 1b of the image forming apparatus 1 is opened so as to expose the sheet transport device 70 and the toner cartridges T (Y), T (M), T (C), and T (K) at the same time, each of the toner cartridges T (Y), T (M), T (C), and T (K) may be replaced by detaching and attaching the toner cartridge from the front (Y direction) of the image forming apparatus 1.
When the toner cartridge is replaced, the image forming section 2 including the sheet transport device 70 is in an operating state. The second front covering 1b is closed after the toner cartridge has been replaced.
The foregoing description of the exemplary embodiment of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiment was chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

## Claims

1. An image forming apparatus comprising:
an image forming section configured to form a toner image;
an output section;
a sheet transport unit configured to transport in a region above the image forming section a sheet onto which the toner image has been fixed toward the output section in a substantially horizontal direction;
an air blowing device; and
an air exhaust device,
wherein a first channel having an air inlet is provided above the sheet being transported so as to cause air to pass from a downstream side to an upstream side in a sheet transport direction of the sheet transport unit,
wherein the air blowing device is configured to apply an airflow by using the first channel,
wherein a second channel having an air outlet is provided at a region above the image forming section and below the sheet so as to cause the air to pass from the downstream side to the upstream side in the sheet transport direction of the sheet transport unit,
wherein the air exhaust device is configured to exhaust the air by using the second channel,
wherein a sheet transport path having a curved portion curved to the image forming section side is provided in the sheet transport unit,
wherein the curved portion forms a recess portion of the sheet transport path, and
wherein the air blowing device is disposed in the recess portion.

2. The image forming apparatus according to claim 1,
wherein the sheet transport unit includes an upper transport member and a lower transport member,
wherein the upper transport member and the lower transport member form a sheet transport path,
wherein the upper transport member has an air blowing opening that is open toward the sheet transport path and that extends in the sheet transport direction, and
wherein the upper transport member is supported such that the upper transport member is movable between a guide position in which the upper transport member guides the sheet and an open position in which the sheet transport path is opened.

3. An image forming apparatus comprising:
an image forming section configured to form a toner image;
an output section;
a sheet transport unit configured to transport in a region above the image forming section a sheet onto which the toner image has been fixed toward the output section in a substantially horizontal direction;
an air blowing device; and
an air exhaust device,
wherein a first channel having an air inlet is provided above the sheet being transported so as to cause air to pass from a downstream side to an upstream side in a sheet transport direction of the sheet transport unit,
wherein the air blowing device is configured to apply an airflow by using the first channel,
wherein a second channel having an air outlet is provided at a region above the image forming section and below the sheet so as to cause the air to pass from the downstream side to the upstream side in the sheet transport direction of the sheet transport unit,
wherein the air exhaust device is configured to exhaust the air by using the second channel,
wherein a sheet transport path having a curved portion curved to the image forming section side is provided in the sheet transport unit, and
wherein the first channel and the second channel communicate with each other in the curved portion.

4. The image forming apparatus according to claim 1,
wherein the first channel and the second channel communicate with each other in the curved portion.

5. The image forming apparatus according to claim 2,
wherein the first channel and the second channel communicate with each other in the curved portion.

6. The image forming apparatus according to claim 3,
wherein the sheet transport unit includes an upper transport member and a lower transport member,
wherein the upper transport member and the lower transport member form a sheet transport path,
wherein the upper transport member has an air blowing opening that is open toward the sheet transport path and that extends in the sheet transport direction, and
wherein the upper transport member is supported such that the upper transport member is movable between a guide position in which the upper transport member guides the sheet and an open position in which the sheet transport path is opened.