JP7658113B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus equipped with a fixing device that forms a nip portion for fixing between a heating member and a pressure member, and in particular to an image forming apparatus that uses a simple configuration to appropriately cool both ends of the heating member or pressure member in the longitudinal direction to prevent excessive heating when a small-sized sheet member (paper) is passed through the nip portion.

In the fixing device of an electrophotographic image forming apparatus, the toner image is heated and fixed by passing paper carrying the toner image through the nip between the heating member (fixing member) and pressure member. When small-sized paper is continuously printed using such a fixing device, the temperature of the longitudinal ends (non-paper passing areas) of the heating member and pressure member may rise excessively (end overheating). When end overheating occurs, the durability of the heating member and pressure member may decrease, paper may wrap around the heating member, causing jams, and problems such as high-temperature offset may occur.

Consequently, in order to prevent the end portions from overheating, cooling air has been blown onto non-paper passing portions at the longitudinal ends of the heating and pressure members. For example, in the fixing device of Patent Document 1, a swingable partition plate arranged in the air supply duct is deployed according to the paper size to appropriately distribute the air volume of the upstream air supply fan along the longitudinal direction of the heating and pressure members. In addition, in the fixing device of Patent Document 2, the air supply duct outlet (nozzle) is arranged so as to be movable along the longitudinal direction of the heating and pressure members.

However, there are nearly 10 different paper sizes, ranging from small to large. For this reason, even with the fixing devices of Patent Documents 1 and 2, it is not easy to adequately cool only the necessary longitudinal ranges of the heating member and pressure member for each paper size.

In other words, to achieve this type of appropriate cooling in Patent Document 1, it is necessary to increase the number of partition plates or to make the partition plates larger. Also, to achieve the appropriate cooling in the device of Patent Document 2, it is necessary to further increase the number of air outlets (nozzles). However, doing so would inevitably result in an increase in the size and complexity of the fixing device, which would increase costs.

The present invention aims to appropriately cool the non-paper passing areas at the longitudinal ends of the heating element and pressure element using a simple configuration.

In order to solve the above problem, the image forming apparatus of the present invention is an image forming apparatus equipped with a fixing device in which a heating member and a pressure member having a longitudinal direction are pressed together to form a nip portion, heat is transferred from the heating member to a sheet member passing through the nip portion, and a toner image carried on the sheet member is heated and fixed, and is characterized in that a duct for blowing air to both longitudinal ends of the heating member or the pressure member is arranged so as to be movable in a direction transverse to the longitudinal direction.

According to the present invention, the non-paper passing portions at the longitudinal ends of the heating member and pressure member can be appropriately cooled with a simple configuration.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of the fixing device according to the first embodiment of the present invention when approaching a duct. FIG. 2 is a plan view of the fixing device according to the first embodiment of the present invention when the duct is separated. 1 is a cross-sectional view of a fixing device in which a fixing belt is used instead of a fixing roller. FIG. 2 is a plan view of a heater that heats the fixing belt. 10A and 10B are a side view and a front view showing a fixing device according to a second embodiment of the present invention when approaching a duct. 10A and 10B are a side view and a front view showing a fixing device according to a second embodiment of the present invention when a duct is separated. 13A and 13B are a side view and a front view showing a fixing device according to a modified example of the second embodiment of the present invention when approaching a duct. 13A and 13B are a side view and a front view showing a fixing device according to a modified example of the second embodiment of the present invention when the duct is separated. 13A and 13B are a plan view and a front view showing a fixing device according to a third embodiment of the present invention when approaching a duct. 13A and 13B are a plan view and a front view showing a fixing device according to a third embodiment of the present invention when a duct is separated. FIG. 13 is a front view of a fixing device according to a fourth embodiment of the present invention when the opening width of an air outlet member is increased. FIG. 13 is a front view of the fixing device according to the fourth embodiment of the present invention when the opening width of the air outlet member is reduced. 6A and 6B are diagrams showing temperature changes of a fixing roller when the rotation speed of a cooling fan is increased or decreased in response to a printing operation of the fixing device. 1A is a plan view of a fixing device when approaching a duct, (b) a plan view showing a state in which the area of the air outlet has been changed when the duct is separated, (c) a plan view showing a state in which the orientation has been changed, and (d) a plan view showing a state in which the shape has been changed. FIG. 13 is a side view of the fixing device according to the fifth embodiment of the present invention when approaching a duct. FIG. 13 is a side view of a fixing device according to a fifth embodiment of the present invention when the duct is separated. 1A is a diagram showing a swinging state of a duct when approaching and FIG. 1B is a diagram showing a swinging state of a duct when moving away. FIG. 13 is a side view of a fixing device according to a sixth embodiment of the present invention when approaching a duct. FIG. 13 is a side view of a fixing device according to a sixth embodiment of the present invention when the duct is separated. FIG. 13 is a plan view of a fixing device according to a seventh embodiment of the present invention when approaching a duct. FIG. 13 is a plan view of a fixing device according to a seventh embodiment of the present invention when the duct is separated.

Below, an embodiment of an image forming apparatus (laser printer) according to the present invention will be described with reference to the drawings. A laser printer is one example of an image forming apparatus, and the image forming apparatus is of course not limited to a laser printer. In other words, the image forming apparatus can be configured as any one of a copier, facsimile, printer, printing machine, and inkjet recording device, or as a multifunction machine that combines at least two or more of these.

In addition, the same or corresponding parts in each figure are given the same reference numerals, and their repeated explanations are appropriately simplified or omitted. Furthermore, the dimensions, materials, shapes, and relative positions of each component part are merely examples, and are not intended to limit the scope of this invention unless otherwise specified.

In the following embodiments, the sheet member (recording medium) will be described as "paper", but the "recording medium" is not limited to paper. The "recording medium" includes not only paper, but also overhead projector sheets, fabric, metal sheets, plastic films, and prepreg sheets made of carbon fibers pre-impregnated with resin.

"Recording media" includes all media onto which developer or ink can be attached, recording paper, and recording sheets. In addition to plain paper, "paper" also includes cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, etc. In the following explanation, "image formation" refers not only to applying images such as letters and figures to a medium, but also to applying patterns and other designs to a medium.

(● Laser printer configuration)
1 is a schematic diagram showing the configuration of a color laser printer as an embodiment of an image forming apparatus 100 equipped with a fixing device 300. The image forming apparatus 100 includes four process units 1K, 1Y, 1M, and 1C as image forming means. These process units form images using developers of the colors black (K), yellow (Y), magenta (M), and cyan (C) that correspond to the color separation components of a color image. The image forming means may be of an indirect transfer type that uses an intermediate transfer belt 16 described below, or of a direct transfer type that does not use the intermediate transfer belt 16 and directly transfers a toner image formed by the process units 1K, 1Y, 1M, and 1C to a sheet of paper.

Each process unit 1K, 1Y, 1M, and 1C has the same configuration, except that it has toner bottles 6K, 6Y, 6M, and 6C that contain unused toner of different colors. For this reason, the configuration of one process unit 1K will be described below, and descriptions of the other process units 1Y, 1M, and 1C will be omitted.

The process unit 1K has an image carrier 2K (e.g., a photosensitive drum), a drum cleaning device 3K, and a charge removal device. The process unit 1K further has a charging device 4K as a charging means for uniformly charging the surface of the image carrier, and a developing device 5K as a developing means for performing visible image processing of the electrostatic latent image formed on the image carrier. The process unit 1K is detachably attached to the main body of the image forming apparatus 100, and consumable parts can be replaced at the same time.

The exposure device 7 is disposed above each of the process units 1K, 1Y, 1M, and 1C installed in the image forming apparatus 100. The exposure device 7 is configured to perform writing scanning according to image information, i.e., to reflect laser light L from a laser diode by a mirror 7a based on image data and irradiate the image carrier 2K.

In this embodiment, the transfer device 15 is disposed below each process unit 1K, 1Y, 1M, and 1C. Primary transfer rollers 19K, 19Y, 19M, and 19C are disposed in contact with the intermediate transfer belt 16, facing each image carrier 2K, 2Y, 2M, and 2C.

The intermediate transfer belt 16 is adapted to circulate around the primary transfer rollers 19K, 19Y, 19M, and 19C, the drive roller 18, and the driven roller 17. The secondary transfer roller 20 is disposed opposite the drive roller 18 and in contact with the intermediate transfer belt 16. If the image carriers 2K, 2Y, 2M, and 2C are the first image carriers for each color, then the intermediate transfer belt 16 is the second image carrier that combines these images.

The belt cleaning device 21 is installed downstream of the secondary transfer roller 20 in the running direction of the intermediate transfer belt 16. In addition, a cleaning backup roller is installed on the opposite side of the intermediate transfer belt 16 from the belt cleaning device 21.

A paper feeder 200 having a tray for stacking paper P is installed below the image forming device 100. This paper feeder 200 constitutes the recording medium supply section, and is capable of storing a large number of sheets of paper P as recording media in a bundle, and is unitized with a paper feed roller 60 and a roller pair 210 as a means for transporting paper P.

The paper feeder 200 can be inserted into and removed from the main body of the image forming device 100 for paper replenishment, etc. The paper feed roller 60 and the roller pair 210 are disposed above the paper feeder 200, and are configured to transport the topmost paper P of the paper feeder 200 toward the paper feed path 32.

The pair of registration rollers 250, which serve as a separation and transport means, are disposed immediately upstream of the secondary transfer roller 20 in the transport direction, and can temporarily stop the paper P fed from the paper feed device 200. This temporary stop creates slack in the leading edge of the paper P, correcting any skew in the paper P.

A registration sensor 31 is disposed immediately upstream of the registration roller pair 250 in the conveying direction, and this registration sensor 31 detects the passage of the leading edge of the paper. After the registration sensor 31 detects the passage of the leading edge of the paper, when a predetermined time has elapsed, the paper is abutted against the registration roller pair 250 and temporarily stopped.

At the downstream end of the paper feeder 200, a transport roller 240 is provided to transport the paper transported to the right from the roller pair 210 upward. As shown in FIG. 1, the transport roller 240 transports the paper upward toward the registration roller pair 250.

The roller pair 210 is composed of a pair of upper and lower rollers. The roller pair 210 can be of the FRR separation type or the FR separation type.

The FRR separation method presses a separation roller (return roller) to which a constant torque is applied in the counter-feed direction by a drive shaft via a torque limiter against the feed roller, separating the paper at the nip between the rollers. The FR separation method presses a separation roller (friction roller) supported on a fixed shaft against the feed roller via a torque limiter, separating the paper at the nip between the rollers.

In this embodiment, the roller pair 210 is configured using the FRR separation method. That is, the roller pair 210 is configured with an upper feed roller 220 that transports paper into the machine, and a lower separation roller 230 that is given a driving force by a drive shaft via a torque limiter in the opposite direction to the feed roller 220.

The separation roller 230 is biased toward the feed roller 220 by a biasing means such as a spring. The feed roller 60 rotates counterclockwise in FIG. 1 by transmitting the driving force of the feed roller 220 via a clutch means.

The paper P, which has been struck by the pair of registration rollers 250 and has a slack at its leading edge, is sent to the secondary transfer nip between the secondary transfer roller 20 and the drive roller 18 in time for the toner image formed on the intermediate transfer belt 16 to be suitably transferred. The toner image formed on the intermediate transfer belt 16 is then electrostatically transferred to the desired transfer position with high precision by the bias applied to the secondary transfer nip.

The post-transfer transport path 33 is disposed above the secondary transfer nip between the secondary transfer roller 20 and the drive roller 18. The fixing device 300 is installed near the upper end of the post-transfer transport path 33. The fixing device 300 includes a fixing roller 310 as a heating member that contains a heat generating member such as a halogen lamp, and a pressure roller 320 as a pressure member that rotates while contacting the fixing roller 310 with a predetermined pressure.

The fixing roller 310 and the pressure roller 320 have longitudinal directions parallel to each other. A nip is formed at the pressure contact portion between the fixing roller 310 and the pressure roller 320, through which a sheet P carrying a toner image is passed to fix the toner image to the sheet.

The post-fixing transport path 35 is disposed above the fixing device 300, and at the upper end of the post-fixing transport path 35, it branches into a paper discharge path 36 and a reverse transport path 41. A switching member 42 is disposed at this branching point, and the switching member 42 is adapted to swing around its swing shaft 42a. In addition, a pair of paper discharge rollers 37 is disposed near the open end of the paper discharge path 36.

The reverse transport path 41 merges with the paper feed path 32 at the other end opposite the branching point. A pair of reverse transport rollers 43 is disposed midway along the reverse transport path 41. The paper output tray 44 is installed on the top of the image forming device 100, forming a concave shape facing inward of the image forming device 100.

The powder container 10 (e.g., a toner container) is disposed between the transfer device 15 and the paper feed device 200. The powder container 10 is removably attached to the main body of the image forming device 100.

The image forming device 100 of this embodiment requires a certain distance between the paper feed roller 60 and the secondary transfer roller 20 due to the transfer paper transport. The powder container 10 is installed in the dead space created by this distance, making the entire laser printer smaller.

The transfer cover 8 is installed on top of the paper feed device 200, directly in front of the paper feed device 200 in the pull-out direction. By opening this transfer cover 8, the inside of the image forming device 100 can be inspected. The transfer cover 8 is equipped with a manual feed roller 45 for manual paper feed, and a manual feed tray 46 for manual paper feed.

(● Laser printer operation)
Next, the basic operation of the laser printer according to this embodiment will be described below with reference to Fig. 1. First, single-sided printing will be described.

As shown in FIG. 1, the paper feed roller 60 rotates in response to a paper feed signal from the control unit of the image forming device 100. The paper feed roller 60 then separates only the topmost sheet of the stack of paper P loaded in the paper feed device 200 and sends it to the paper feed path 32.

When the leading edge of the paper P sent out by the paper feed roller 60 and the roller pair 210 reaches the nip of the registration roller pair 250, it forms a slack and waits in that state. Then, the toner image formed on the intermediate transfer belt 16 is transferred to the paper P at the optimal timing (synchronization), and the leading edge skew of the paper P is corrected.

When feeding paper manually, a stack of paper sheets stacked on the manual feed tray 46 is transported one by one, starting from the topmost sheet, through a part of the inverted transport path 41 by the manual feed roller 45 to the nip of the registration roller pair 250. The subsequent operation is the same as when feeding paper from the paper feed device 200.

Here, the image forming operation will be explained for one process unit, 1K, and explanations for the other process units, 1Y, 1M, and 1C, will be omitted. First, the charging device 4K uniformly charges the surface of the image carrier 2K to a high potential. Then, the exposure device 7 irradiates the surface of the image carrier 2K with laser light L based on the image data.

When the surface of the image carrier 2K is irradiated with the laser light L, the potential of the irradiated area decreases, forming an electrostatic latent image. The developing device 5K has a developer carrier that carries a developer containing toner, and transfers unused black toner supplied from the toner bottle 6K via the developer carrier to the surface portion of the image carrier 2K on which the electrostatic latent image is formed.

The image carrier 2K to which the toner has been transferred forms (develops) a black toner image on its surface. The toner image formed on the image carrier 2K is then transferred to the intermediate transfer belt 16.

The drum cleaning device 3K removes residual toner adhering to the surface of the image carrier 2K after the intermediate transfer process. The removed residual toner is sent by a waste toner transport means to a waste toner storage section in the process unit 1K for collection. In addition, the charge removal device removes residual charge from the image carrier 2K from which the residual toner has been removed by the cleaning device 3K.

In the process units 1Y, 1M, and 1C for each color, toner images are formed on the image carriers 2Y, 2M, and 2C in the same manner, and the toner images of each color are transferred to the intermediate transfer belt 16 so that they are superimposed.

The intermediate transfer belt 16, on which the toner images of each color have been transferred so as to overlap, travels to the secondary transfer nip between the secondary transfer roller 20 and the drive roller 18. Meanwhile, the pair of registration rollers 250 rotates, nipping the paper that is abutted against them at a predetermined timing, and transports the paper to the secondary transfer nip of the secondary transfer roller 20 in accordance with the timing at which the toner images formed by superimposing and transferring onto the intermediate transfer belt 16 are appropriately transferred. In this way, the toner image on the intermediate transfer belt 16 is transferred to the paper P sent out by the pair of registration rollers 250.

The paper P with the toner image transferred thereto is transported to the fixing device 300 via the post-transfer transport path 33. The paper P transported to the fixing device 300 is then sandwiched between the fixing roller 310 and the pressure roller 320, where the unfixed toner image is fixed to the paper P by applying heat and pressure. The paper P with the fixed toner image is sent from the fixing device 300 to the post-fixing transport path 35.

When the paper P is sent out from the fixing device 300, the switching member 42 is in a position that opens the vicinity of the upper end of the post-fixing transport path 35, as shown by the solid line in FIG. 1. The paper P sent out from the fixing device 300 is then sent out to the paper discharge path 36 via the post-fixing transport path 35. The paper discharge roller pair 37 pinches the paper P sent out to the paper discharge path 36 and rotates to discharge the paper onto the paper discharge tray 44, thereby completing single-sided printing.

Next, the case of double-sided printing will be described. As in the case of single-sided printing, the fixing device 300 sends the paper P to the paper discharge path 36. Then, when performing double-sided printing, the pair of paper discharge rollers 37 are driven to rotate to transport a portion of the paper P outside the image forming device 100.

Then, when the rear end of the paper P passes through the paper discharge path 36, the switching member 42 swings about the swing shaft 42a as shown by the dotted line in FIG. 1, and closes the upper end of the post-fixing transport path 35. Almost simultaneously with the closing of the upper end of the post-fixing transport path 35, the pair of paper discharge rollers 37 rotates in the direction opposite to the direction in which the paper P is transported out of the image forming device 100, and sends the paper P to the reverse transport path 41.

The paper P sent to the reverse transport path 41 passes through the reverse transport roller pair 43 and reaches the registration roller pair 250. The registration roller pair 250 then determines the optimal timing (synchronization) for transferring the toner image formed on the intermediate transfer belt 16 to the non-transferred surface of the paper P, and sends the paper P to the secondary transfer nip.

Then, the secondary transfer roller 20 and the drive roller 18 transfer the toner image to the non-transferred surface (reverse surface) of the paper P as the paper P passes through the secondary transfer nip. The paper P with the transferred toner image is then transported to the fixing device 300 via the post-transfer transport path 33.

The fixing device 300 clamps the conveyed paper P between the fixing roller 310 and the pressure roller 320, and applies heat and pressure to fix the unfixed toner image to the back side of the paper P. In this way, the paper P with the toner images fixed on both sides is sent from the fixing device 300 to the post-fixing transport path 35.

When the paper P is sent out from the fixing device 300, the switching member 42 is in a position that opens the vicinity of the upper end of the post-fixing transport path 35, as shown by the solid line in FIG. 1. The paper P sent out from the fixing device 300 is then sent out to the paper discharge path 36 via the fixing transport path. The pair of paper discharge rollers 37 clamp the paper P sent out to the paper discharge path 36, rotate and discharge the paper to the paper discharge tray 44, completing double-sided printing.

After the toner image on the intermediate transfer belt 16 is transferred to the paper P, residual toner remains on the intermediate transfer belt 16. The belt cleaning device 21 removes this residual toner from the intermediate transfer belt 16. The toner removed from the intermediate transfer belt 16 is transported by the waste toner transport means to the powder container 10 and collected in the powder container 10.

(First embodiment)
2A and 2B, a fixing device 300 used in the image forming apparatus 100 according to the first embodiment of the present invention will be described. The fixing device 300 is composed of a fixing roller 310 as a heating member incorporating a halogen lamp HL, and a pressure roller 320 as a pressure member that is in pressure contact with the fixing roller 310. A fixing nip SN is formed between the fixing roller 310 and the pressure roller 320, through which a sheet carrying a toner image passes.

The fixing device 300 may be of a roller fixing type or a belt fixing type. In either fixing type, when a toner image formed on small size paper P is heated and fixed, the heat of the heater is absorbed by the paper P in areas where the paper P passes, but in areas where the paper P does not pass, the heat of the heater is not absorbed by the paper P, which can cause overheating. This embodiment appropriately suppresses such overheating with a simple configuration.

Thermistors TH1 to TH3 are arranged close to the surface of the fixing roller 310 as temperature detection members that detect the surface temperature. These thermistors TH1, TH2, and TH3 make it possible to detect the surface temperature of the fixing roller 310.

The central thermistor TH1 is located in the longitudinal center of the fixing roller 310. The thermistors TH2 and TH3 at both ends are located in non-paper passing areas on the outer side in the width direction of large size paper. The power supplied to the halogen lamp HL is controlled based on the temperature information from thermistors TH1 to TH3 to suppress temperature rise in the non-paper passing areas of the fixing roller 310.

Thermistors TH1 to TH3 can be replaced with thermistors arranged opposite the outer circumferential surface of pressure roller 320. Various types of fixing device 300 are possible, and the fixing device 300 shown in Figures 2A and 2B described above is merely one example.

(Belt-type fixing device)
In the first embodiment, the fixing roller 310 is used as the heating member, but it is also possible to use a fixing belt 311 as shown in Fig. 2C instead of the fixing roller 310. The fixing device 300 of the belt fixing method in Fig. 2C is composed of a thin fixing belt 311 with low heat capacity and a pressure roller 320. The fixing belt 311 has a cylindrical body made of polyimide (PI) with an outer diameter of 25 mm and a thickness of 40 to 120 µm, for example.

When a toner image formed on small-size paper P is heated and fixed using either the roller fixing method of Figures 2A and 2B or the belt fixing method of Figure 2C, the small-size paper P absorbs the heat of the heater in areas where the small-size paper P passes, but in areas where the small-size paper P does not pass, the small-size paper P does not absorb the heat of the heater, which can result in overheating.

The pressure roller 320 has an outer diameter of, for example, 25 mm, and is composed of a solid iron core 321, an elastic layer 322 formed on the surface of the core 321, and a release layer 323 formed on the outside of the elastic layer 322. The elastic layer 322 is made of silicone rubber and has a thickness of, for example, 3.5 mm.

To improve releasability, it is desirable to form a release layer 323 made of a fluororesin layer having a thickness of, for example, about 40 μm on the surface of the elastic layer 322. A pressure roller 320 is pressed against the fixing belt 311 by a biasing means.

A stay 350 and a heater holder 340 are arranged in the axial direction inside the fixing belt 311. The stay 350 is made of a metal channel material, and both ends are supported by both side plates of the fixing device 300. The stay 350 reliably receives the pressing force of the pressure roller 320 to stably form the fixing nip SN.

The heater holder 340 is for holding the base material 341 of the heater 330 of the fixing device 300, and is supported by the stay 350. The heater holder 340 is preferably formed from a heat-resistant resin with low thermal conductivity, such as LCP, which reduces heat transfer to the heater holder 340 and allows the fixing belt 311 to be heated efficiently.

The heater holder 340 is shaped to support only two points near both ends of the substrate 341 in the short direction to avoid contact with the high-temperature parts of the substrate 341. This further reduces the amount of heat flowing to the heater holder 340, allowing the fixing belt 311 to be heated efficiently.

A thermistor TH1 is disposed on the back surface of the substrate 341 as a central temperature detection member that detects the temperature of the heating elements 372-376 of the heater 330 (described below). Thermistor TH1 is pressed against the back surface of the substrate 341 by a spring 387, thereby enabling accurate temperature detection of the heating elements 372-376.

The temperature of the inner surface of the fixing belt 311 downstream of the fixing nip SN is detected by thermistor TH2 as a central temperature detection member and thermistor TH3 as an end temperature detection member. One thermistor, TH2, is disposed in the longitudinal center of the heater 330, similar to thermistor TH1. The other thermistor, TH3, is disposed at the longitudinal end (non-paper passing portion) of the heater 330.

Thermistors TH1 and TH2 are positioned in the center of the width of small-size paper. Thermistor TH3 is positioned in the non-paper-passing outer portion of the width of large-size paper. Based on the temperature information from thermistors TH1 to TH3, the power supplied to heater 330 is controlled to suppress temperature rise in the non-paper-passing portions of fixing belt 311.

Thermistors TH1 to TH3 can be replaced with thermistors arranged opposite the outer circumferential surface of pressure roller 320. By arranging the thermistor on the pressure roller 320 side on the outside of fixing belt 311, maintenance of the thermistor becomes easier. Various types of fixing device 300 are possible, and the fixing device of Figures 2A to 2C described above is just one example.

(● Heater)
2D shows an example of the heater 330 described above, which has three electrodes 370h, 370i, and 370j disposed on both ends of the substrate 341, and seven heating elements 371 to 377 disposed between the electrodes in the longitudinal direction of the substrate 341. The following three heating patterns can be selected by the method of connecting an AC power source to the electrodes 370h, 370i, and 370j.
Heating pattern 1: Only the central heating elements 372 to 376 generate heat (for example, when heating small size A4 paper)
Heating pattern 2: All heating elements 371 to 377 generate heat (for example, when heating large size A3 paper)
Heating pattern 3: Heat is generated only by the end heating elements 371 and 377 (for example, when preventing a drop in end temperature when heating A3 paper)

Here, the central heating elements 372 to 376 are referred to as central heater H1, and the heating elements 371 and 377 at both ends are referred to as end heaters H2. The central heater H1 and end heaters H2 are positioned so as not to overlap each other when viewed from the short side direction perpendicular to the long side direction of the heater 330.

Five heating elements 372-376 in the center of the heater 330 in the longitudinal direction are connected in parallel to the first electrode 370h and the second electrode 370i via conductors 370e and 370f that have a lower resistance than the heating elements. In addition, two resistive heating elements 371 and 377 at both ends in the longitudinal direction are connected in parallel to the second electrode 370i and the third electrode 370j via conductors 370f and 370g that have a lower resistance than the heating elements 371 and 377.

The second electrode 370i on the right side is always connected to an AC power source, and the first electrode 370h and the third electrode 370j on the left side are selectively connected to the AC power source by switching a switch. This allows the three heating patterns 1 to 3 mentioned above to be selected.

In this heater 330, which can select from three heat generation patterns, the longitudinal length of the five consecutive heating elements 372-376 in the longitudinal center of the heater 330 is set to the same width as A4 paper, and the longitudinal length of all seven heating elements 371-377 including both ends is set to the same width as A3 paper. Then, by appropriately controlling the heating state of the heating elements 371-377, it is possible to heat A4-size and A3-size paper evenly.

The heating of the heating elements 371-377 is generally controlled by varying the lighting time (lighting duty) of the heating elements within a specified control time to obtain the appropriate amount of heat. The lighting duty is adjusted by phase-controlling the AC power supply with a triac as the control means. The current is zero at a duty ratio of 0% and maximum at a duty ratio of 100%.

The heating elements 371 to 377 can be composed of, for example, PTC elements. PTC elements are composed of a material with a positive temperature coefficient of resistance, and have the characteristic that their resistance value increases as the temperature T increases (the current I decreases, and the heater output decreases). The temperature coefficient of resistance (TCR) can be, for example, 1500 PPM (parts per million).

The heating elements 371 to 377 are formed on a substrate 341, which is a long, thin metal plate member covered with an insulating material. Low-cost materials such as aluminum and stainless steel are preferred as materials for the substrate 341. The substrate 341 is not limited to being made of metal, and can also be made of ceramics such as alumina and aluminum nitride, or non-metallic materials with excellent heat resistance and insulation properties, such as glass and mica.

(● Duct configuration)
2A and 2B, a duct 510 is disposed on the opposite side of the pressure roller 320 from the fixing roller 310. Cooling air is blown out through this duct 510 to both ends of the pressure roller 320 in the longitudinal direction.

The duct 510 has a symmetrical structure, with one intake port 510a located in the center of the pressure roller 320 in the longitudinal direction, and a pair of left and right air outlets 510b located at both ends of the pressure roller 320 in the longitudinal direction. The downstream side of the intake port 510a branches into two and continues to the pair of left and right air outlets 510b. A blower fan 530 is disposed in the intake port 510a, which introduces outside air into the duct 510 and blows the air out of the pair of left and right air outlets 510b toward both ends of the pressure roller 320 in the longitudinal direction.

Blow-outlet members 550a, 550b can be provided on the pair of left and right blow-out ports 510b as necessary. These blow-out port members 550a, 550b adjust the opening area of the blow-out port 510b to increase or decrease, and there are multiple types of adjustments available, as shown in Figures 3A, 3B, 3A', 3B', 4A, 4B, and 5A, 5B, which will be described later.

The duct 510 is arranged to be movable in a direction transverse to the longitudinal direction of the pressure roller 320 (up and down in Figs. 2A and 2B, left and right in Fig. 2C). The amount of movement of the duct 510 can be changed according to the paper size information.

In this embodiment, the duct 510 is arranged to be movable in a direction perpendicular to the longitudinal direction of the pressure roller 320, but the direction of movement of the duct 510 is not limited to a direction perpendicular to the longitudinal direction. The duct 510 may also be moved in an inclined direction that forms a predetermined angle (for example, a predetermined angle between 0° and 10°) with the direction perpendicular to the longitudinal direction of the pressure roller 320.

Figure 2A shows the state in which the duct 510 is closest to the pressure roller 320, and Figure 2B shows the state in which the duct 510 is farthest from the pressure roller 320. In Figure 2A, in which the duct 510 is closest to the pressure roller 320, the diffusion range L1 of the air flows Wa and Wb emitted from the air outlet 510b is narrow in the longitudinal direction. Therefore, the air volume of the blower fan 530 is supplied intensively to the narrow diffusion range L1 in the longitudinal direction.

When large-sized paper is passed through the fixing nip, the longitudinal range of the non-paper passing portion is narrowed, and the longitudinal range of the end overheating is also narrowed. Therefore, under such printing conditions, as shown in FIG. 2A, the duct 510 is brought closest to the pressure roller 320, and air is blown out in a concentrated manner into a narrow diffusion range L1. In FIG. 2A, the air volume per unit area is increased, allowing limited areas at both longitudinal ends of the pressure roller 320 to be cooled in a concentrated manner.

In contrast, in FIG. 2B, where the duct 510 is at the furthest distance from the pressure roller 320, the diffusion range L2 of the airflows Wa and Wb coming out of the air outlet 510b becomes wider in the longitudinal direction. Therefore, the air volume of the blower fan 530 is distributed and supplied over the wide diffusion range L2 in the longitudinal direction.

When small-sized paper is passed through the fixing nip, the longitudinal range of the non-paper passing portion becomes wider, and the longitudinal range of the end overheating also becomes wider. Therefore, under such printing conditions, as shown in FIG. 2B, the duct 510 is moved farthest away from the pressure roller 320, and air is blown out over a wide diffusion range L2. In this way, as shown in FIG. 2B, a wider area can be cooled at both longitudinal ends of the pressure roller 320.

As shown in Figures 2A and 2B, the duct 510 is arranged to be movable in a direction transverse to the longitudinal direction of the pressure roller 320, so that the cooling area of the pressure roller 320 can be switched. Therefore, in response to excessive temperature rise at the end of the pressure roller 320, the area that needs to be cooled according to the paper size can be effectively cooled with a simple configuration.

In other words, a simple configuration can be used to effectively cool areas that require cooling according to the paper size in response to excessive temperature rise at the ends. Also, by moving the duct 510 based on paper size information, it is possible to eliminate the need for multiple temperature detection means such as thermistors and a complex configuration for moving the duct in the longitudinal direction, and a simple configuration can be used to cool according to the paper size in response to excessive temperature rise at the ends.

(Second embodiment)
Next, the cooling structure of the fixing device 300 according to the second embodiment of the present invention will be described with reference to Figures 3A and 3B. This cooling structure adjusts the vertical width of the air outlet 510b by adjusting the air outlet member 550 (550a, 550b) without changing the longitudinal width of the air outlet 510b. The rest of the structure is the same as that of the first embodiment described above with reference to Figures 2A and 2B.

The air outlet members 550 are composed of elongated members with an L-shaped cross section, and are arranged in pairs above and below the air outlet 510b. The upper and lower air outlet members 550 are each rotatable around a fulcrum pin 551 that is fixed in position. By rotating the air outlet members 550 with a driving means such as a motor, the vertical width of the air outlet 510b can be increased or decreased.

Figure 3A shows the state in which the duct 510 is closest to the pressure roller 320. At this time, the airflow coming out of the air outlet 510b is blown out into a narrow diffusion range L1 in the longitudinal direction, like the airflows Wa and Wb shown in Figure 2A. However, the vertical width W1 of the air outlet 510b is at its maximum (maximum opening area).

As a result, the air flows Wa and Wb cool a wide angular range of the peripheral surface of the pressure roller 320. When large-size paper is passed through the fixing nip, the longitudinal range in which excessive temperature rise occurs at the ends is narrow, so the duct 510 is placed closest to the pressure roller 320 for cooling, as shown in FIG. 3A.

In contrast, FIG. 3B shows the state in which the duct 510 is farthest from the pressure roller 320. At this time, the airflow coming out of the air outlet 510b is blown out over a wide diffusion range L2 in the longitudinal direction, like the airflows Wa and Wb shown in FIG. 2B. However, the vertical width W2 of the air outlet 510b is at its minimum (smallest opening area).

As a result, the air flows Wa and Wb concentrate on cooling a narrow angle range of the peripheral surface of the pressure roller 320. When small-sized paper is passed through the fixing nip, the longitudinal range in which excessive heating of the ends occurs is wide, so the duct 510 is moved as far away from the pressure roller 320 as shown in FIG. 3B for cooling. Even when the duct 510 is moved to the farthest position from the pressure roller 320, the vertical width W2 of the air outlet 510b is at its smallest, so the wind speed of the air outlet 510b can be increased, thereby increasing the cooling effect.

The size of the vertical width W2 can be changed according to the paper size, thereby more effectively suppressing excessive temperature rise at the ends. The vertical width W2 can be changed by controlling the drive amount of the motor that drives the shutter member 550.

The vertical width of the air outlet 510b gradually narrows as the duct 510 moves away from the pressure roller 320. Therefore, depending on the paper size, air can be blown out from the air outlet 510b with the duct 510 stopped at a predetermined intermediate position between Figures 3A and 3B.

(Modification of the second embodiment)
Next, a modified example of the second embodiment of the present invention will be described with reference to Figures 3A' and 3B'. In this modified example, the air outlet member 550 of Figures 3A and 3B is rotatably disposed at the tip of the duct 510.

That is, the corners of the air outlet member 550, which has an L-shaped cross section, are rotatably supported by a support shaft 556 provided at the tip of the duct 510. A torsion spring wound around the support shaft 556 biases the air outlet member 550 in the opening direction.

On the other hand, one end of the air outlet member 550 is connected to a fixed pin 557 that is fixed in position by a tension spring SP4. The air outlet member 550 is biased in the closing direction by the tension spring SP4.

Therefore, when the duct 510 is closest to the pressure roller 320 as shown in Figure 3A', the tension spring SP4 remains compressed, so the air outlet member 550 is wide open by the biasing force of the torsion spring wound around the support shaft 556 (maximum opening area). In contrast, when the duct 510 is farthest from the pressure roller 320 as shown in Figure 3B', the tension spring SP4 is stretched, and the biasing force in the closing direction by this tension spring SP4 becomes dominant, so the vertical width W2 of the air outlet member 550 becomes minimum (minimum opening area).

As a result, even if the duct 510 is separated from the pressure roller 320 as shown in FIG. 3B', the air flows Wa and Wb are narrowed by the vertical width W2, so that a narrow angle range of the peripheral surface of the pressure roller 320 can be concentrated for cooling. When small-sized paper is passed through the fixing nip, the longitudinal range in which excessive temperature rise occurs at the ends is wide, so the duct 510 is placed as far away from the pressure roller 320 as possible for cooling as shown in FIG. 3B'.

Even when the duct 510 is at the farthest point from the pressure roller 320, the vertical width W2 of the air outlet 510b is at its smallest, so the air speed of the air outlet 510b can be increased, thereby increasing the cooling effect. The size of the vertical width W2 can be changed according to the paper size, which makes it possible to more effectively prevent excessive temperature rise at the ends.

The vertical width of the air outlet 510b gradually narrows as the duct 510 moves away from the pressure roller 320 because the tension spring SP4 is stretched. Therefore, depending on the paper size, air can be blown out from the air outlet 510b with the duct 510 stopped at a predetermined intermediate position between Figures 3A and 3B.

(Third embodiment)
Next, a cooling structure of a fixing device 300 according to a third embodiment of the present invention will be described with reference to Figures 4A and 4B. This cooling structure adjusts the longitudinal width of the air outlet 510b without changing the vertical width. The rest of the structure is the same as that of the first embodiment described above with reference to Figures 2A and 2B.

The slider members 570a and 570b are composed of U-shaped or bifurcated comb-like members, and are arranged inside the air outlet 510b with the base (connecting part) of the slider members 570a and 570b at the center in the longitudinal direction. The longitudinal width of the air outlet 510b can be increased or decreased by sliding the slider members 570a and 570b in the longitudinal direction according to the paper size using a driving means such as a motor.

Figure 4A shows the state in which the duct 510 is closest to the pressure roller 320, and the slider members 570a and 570b have moved to both ends in the longitudinal direction. At this time, the longitudinal width of the air outlet 510b is at its minimum (opening area S1, longitudinal opening width L1).

Figure 4B shows the state in which the duct 510 is farthest from the pressure roller 320, and the slider members 570a and 570b have moved toward the center in the longitudinal direction as indicated by arrows B and C. At this time, the longitudinal width of the air outlet 510b is at its maximum (opening area S2, longitudinal opening width L2).

The opening areas S1, S2 and the longitudinal opening widths L1, L2 can be changed according to the paper size, thereby more effectively suppressing excessive heating at the ends. In other words, by setting the opening area S1 and the longitudinal opening width L1 for small size paper, and the opening area S2 and the longitudinal opening width L2 for large size paper, excessive heating at the ends can be more effectively suppressed.

(Fourth embodiment)
Next, the cooling structure of the fixing device 300 according to the third embodiment of the present invention will be described with reference to Figures 5A and 5B. This cooling structure is a type that adjusts both the vertical width and the longitudinal width of the air outlet 510b. The air outlet members 550a and 550b are the same as those described in Figures 3A and 3B. The slider members 570a and 570b are the same as those described in Figures 4A and 4B.

In FIG. 5A, the duct 510 is closest to the pressure roller 320, and the air outlet members 550a and 550b are fully open, so the vertical width W1 of the air outlet 510b is at its maximum. Also, because the slider members 570a and 570b have moved to both ends in the longitudinal direction, the longitudinal width of the air outlet 510b is at its minimum (opening area S1).

In FIG. 5B, the duct 510 is at its farthest position from the pressure roller 320, and the air outlet members 550a and 550b are narrowed, so the vertical width W2 of the air outlet 510b is at its smallest. Also, the slider members 570a and 570b have moved toward the center in the longitudinal direction as indicated by the arrows B and C, so the longitudinal width of the air outlet 510b is at its largest (opening area S2).

The opening areas S1 and S2, longitudinal opening widths L1 and L2, and vertical widths W1 and W2 of the air outlet 510b can be changed according to the paper size, thereby more effectively preventing excessive heating at the ends. That is, by setting the opening area S1, longitudinal opening width L1, and vertical width W1 for small-sized paper, and the opening area S2, longitudinal opening width L2, and vertical width W2 for large-sized paper, excessive heating at the ends can be more effectively prevented.

(● Controlling the rotation speed of the blower fan)
The rotation speed of the blower fan 530 may be increased or decreased in conjunction with the movement position of the duct 510 corresponding to the paper size, and the adjustment of the air outlet members 550 (550a, 550b) and slider members 570a, 570b. By combining the configuration of the duct 510 and the rotation speed of the blower fan 530, it is possible to provide an effective fixing device that suppresses excessive temperature rise at the end portions.

Figure 6 shows the temperature change of the fixing roller 310 when the rotation speed of the blower fan 530 is increased or decreased in response to the printing operation (printing or standby) of the fixing device 300. The temperature of the fixing roller 310 is represented by the detected temperature of thermistors TH1 and TH2. To prevent the end portion of the fixing roller 310 from overheating, the temperature difference ΔT between thermistors TH1 and TH2 is made as small as possible.

When printing begins, the central temperature TH1 of the fixing roller is printed at the specified temperature. When small size paper is passed through, the end temperature TH2 becomes higher than the central temperature TH1. When the temperature difference between the central temperature TH1 and the end temperature TH2 becomes ΔT1, the rotation speed of the cooling fan switches from Low to Middle, and when the temperature difference becomes ΔT10, the rotation speed of the cooling fan switches from Middle to High until the end temperature TH2 decreases to the temperature difference ΔT2.

When the temperature difference becomes ΔT2, the cooling fan speed changes from High to Middle. When the printing operation ends and the temperature difference becomes ΔT1, the cooling fan speed changes from Middle to Low and goes into standby mode.

(Type of change of air outlet)
In the first to fourth embodiments described above, the duct 510 is moved toward or away from the pressure roller 320, and the opening area of the air outlet 510b is increased or decreased. However, the present invention can be implemented in other ways. That is, as shown in Fig. 7(a) and (b), the opening area of the air outlet 510b is changed (opening area CA1, CA2 -> opening area CA3, CA4), the direction of the air outlet of the duct 510 may be changed as shown in Fig. 7(c), or the shape of the air outlet of the duct 510 may be changed as shown in Fig. 7(d).

In this way, any one of the position, shape, orientation, and opening area of the air outlet can be made changeable in response to paper size, or any two or more of the position, shape, orientation, and opening area of the air outlet can be made changeable in response to paper size. By making any two or more of the position, shape, orientation, and opening area of the air outlet changeable in response to paper size as in the latter case, excessive temperature rise at the end of the fixing roller 310 or the pressure roller 320 can be more effectively suppressed than when only one of them is changeable. The position, shape, orientation, and opening area of the air outlet can be changed by using a known slider mechanism, cam mechanism, link mechanism, etc., alone or in combination.

(Fifth embodiment)
Next, a cooling structure of a fixing device 300 according to a fifth embodiment of the present invention will be described with reference to Figures 8A to 8C. In this embodiment, the orientation of the air outlet member 550 is changed in the vertical direction in conjunction with the approaching and receding movement of the duct 510 relative to the pressure roller 320. The vertical width of the air outlet 510b is almost the same (W1 ≒ W2) between the orientations of the air outlet member 550 in Figures 8A and 8B.

The air outlet members 550 arranged above and below the air outlet 510b can swing up and down around a fixed fulcrum pin 552, as shown in FIG. 8C. The tips of the air outlet members 550 are connected to each other by a connecting member 554. The lower air outlet member 550 is biased upward by a compression spring SP1.

When the duct 510 is approaching the pressure roller 320 as shown in FIG. 8A, the tip of the duct 510 is inserted between the air outlet member 550, and the air outlet member 550 faces horizontally. The biasing force of the compression spring SP1 acts on the air outlet member 550, but the tip of the duct 510 interferes with the air outlet member 550, so the air outlet member 550 cannot tilt upward.

In contrast, when the duct 510 moves away from the pressure roller 320 in the direction of arrow A as shown in FIG. 8B, the tip of the duct 510 is pulled out from between the air outlet members 550. As a result, the air outlet members 550 become free to swing, and the air outlet members 550 tilt upward around the fulcrum pin 552 due to the biasing force of the compression spring SP1.

Therefore, the air blown out from the tip of the duct 510 is guided diagonally upward by the air outlet member 550 and blown in a nearly tangential direction against the outer circumferential surface of the pressure roller 320. As a result, air is blown over a wide angular range in the circumferential direction of the outer circumferential surface of the pressure roller 320, enhancing the cooling effect of the non-paper passing portions at both ends of the pressure roller 320.

(Sixth embodiment)
Next, a cooling structure of the fixing device 300 according to the sixth embodiment of the present invention will be described with reference to Figs. 9A and 9B. In this embodiment, the orientation of the blow-out member 550 is changed in the vertical direction in conjunction with the approaching and receding movement of the duct 510 relative to the pressure roller 320. That is, when the duct 510 is approaching the pressure roller 320 as shown in Fig. 9A, the blow-out member 550 faces the horizontal direction (vertical width W1), but when the duct 510 moves away from the pressure roller 320 in the direction of the arrow A as shown in Fig. 9B, the blow-out member 550 opens in the vertical direction by the biasing force of the tension spring SP2 (vertical width W2).

The air outlet members 550, which are disposed above and below the air outlet 510b, are capable of swinging up and down around a fixed fulcrum pin 553. A tension spring SP2 is connected to the tip of the air outlet member 550. In the state shown in FIG. 9A, even if the air outlet member 550 tries to open due to the biasing force of the tension spring SP2, the tip of the duct 510 interferes with the air outlet member 550, so the air outlet member 550 does not open.

In contrast, as shown in FIG. 9B, when the duct 510 moves away from the pressure roller 320 as indicated by the arrow A, the air outlet member 550 becomes free to swing and opens outward due to the biasing force of the tension spring SP2. As a result, the air blown out from the tip of the duct 510 is blown from the vertical width W2 over a wide angular range on the outer circumferential surface of the pressure roller 320, enhancing the cooling effect of the non-paper passing portions at both ends of the pressure roller 320.

(Seventh embodiment)
Next, the cooling structure of the fixing device 300 according to the seventh embodiment of the present invention will be described with reference to Figures 10A and 10B. In this embodiment, the approach and separation of the duct 510 from the pressure roller 320 is performed in accordance with the paper size. That is, for example, when a large size paper is passed through, the end overheating occurs in a relatively narrow range at both ends of the pressure roller 320 in the longitudinal direction, so the duct 510 is brought close to the pressure roller 320 as shown in Figure 10A to blow out air. On the other hand, when a small size paper is passed through, the end overheating range expands to a wide range at both ends of the pressure roller 320 in the longitudinal direction, so the duct 510 is moved away from the pressure roller 320 as shown in Figure 10B to blow out air.

A pair of left and right air outlet members 550 are arranged rotatably around support shafts 555 near the left and right air outlets 510b that blow air out from the duct 510. The air outlet members 550 are biased in the outward opening direction by tension springs SP3.

When the duct 510 is approaching the pressure roller 320 as shown in FIG. 10A, the outer surfaces of the pair of left and right air outlet members 550 are pushed in a closing direction by the inner surface of the duct 510, so the left and right air outlet members 550 face each other in a nearly parallel state. Therefore, air can be blown out within an appropriate range to counter the end overheating that occurs in a relatively narrow range at both ends of the pressure roller 320 in the longitudinal direction when large-sized paper is passed through.

On the other hand, when the duct 510 moves away from the pressure roller 320 as shown in FIG. 10B, the pair of left and right air outlet members 550 are biased outward by the tension spring SP3 and open wide. Therefore, air can be blown out within an appropriate range to counter the end overheating that occurs over a wide range at both longitudinal ends of the pressure roller 320 when small-sized paper is passed through.

(Modification of the seventh embodiment)
10A and 10B, the air outlet members 550 shown in Fig. 3A and 3B may be disposed. That is, the air outlet members 550 may be disposed above, below, left and right of the air outlet.

As a result, as shown in FIG. 10B, the opening of the air outlet member 550 can be narrowed in the vertical direction and widened in the longitudinal direction as the duct 510 moves away from the pressure roller 320. Here, the "vertical direction" refers to a direction perpendicular to both the longitudinal direction of the pressure roller 320 and the direction of movement of the duct 510.

By doing this, when the duct 510 is separated from the pressure roller 320, strong air flows Wa and Wb can be directed at both ends of the pressure roller 320 in the longitudinal direction over a wide range of the pressure roller 320. Therefore, excessive temperature rise at the ends of the fixing roller 310 or the pressure roller 320 can be suppressed more effectively than in the case of FIG. 10B.

The present invention has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways within the scope of the technical ideas described in the claims. For example, instead of cooling the pressure roller 320 with air from the duct 510, the fixing roller 310 can be cooled directly. In addition, the halogen lamp HL that heats the fixing roller 310 can be replaced with other heating elements, such as a heater using a PTC element or a ceramic heater.

100: Image forming apparatus 300: Fixing device 310: Fixing roller (heating member) 311: Fixing belt (heating member)
320: Pressure roller (pressure member) 330: Heater 340: Heater holder 350: Stay 510: Duct 510a: Intake port 510b: Air outlet 530: Blower fan
550, 550a, 550b: Air outlet member 551 to 553: Pivot pin 554: Connecting member 555, 556: Support shaft 557: Fixing pin 570a, 570b: Slider member SN: Fixing nip (nip portion) SP1: Compression spring SP2 to SP4: Tension spring TH1 to TH3: Thermistor

JP 2006-119259 A JP 2003-66762 A

Claims (7)

An image forming apparatus including a fixing device in which a heating member having a longitudinal direction and a pressure member are in pressure contact with each other to form a nip portion, heat is transferred from the heating member to a sheet member passing through the nip portion, and a toner image carried on the sheet member is heated and fixed,
an image forming apparatus comprising: a duct for blowing air to both ends in a longitudinal direction of said heating member or said pressure member, said duct being disposed so as to be movable in a direction transverse to said longitudinal direction; The image forming device according to claim 1, characterized in that at least one of the position, shape, direction, and opening area of the air outlet that blows out the air from the duct is configured to be changeable. The image forming device according to claim 1, characterized in that two or more of the position, shape, direction, and opening area of the air outlet that blows out the air from the duct are changeable. The image forming device according to claim 2 or 3, characterized in that the movement position of the duct and the position, shape, direction, and opening area of the air outlet are changeable in accordance with the size of the sheet member. An image forming device according to any one of claims 2 to 4, characterized in that the position, shape, direction, and opening area of the air outlet are configured to be changeable in conjunction with the movement of the duct. An image forming apparatus including a fixing device in which a heating member having a longitudinal direction and a pressure member are in pressure contact with each other to form a nip portion, heat is transferred from the heating member to a sheet member passing through the nip portion, and a toner image carried on the sheet member is heated and fixed,
an image forming apparatus comprising: a duct for blowing air toward both longitudinal ends of the heating member or the pressure applying member, the duct being arranged so as to be movable in a direction transverse to the longitudinal direction; and an opening of an outlet for blowing air from the duct gradually narrowing as the duct moves away from the heating member or the pressure applying member in the direction transverse to the longitudinal direction. An image forming apparatus including a fixing device in which a heating member having a longitudinal direction and a pressure member are in pressure contact with each other to form a nip portion, heat is transferred from the heating member to a sheet member passing through the nip portion, and a toner image carried on the sheet member is heated and fixed,
an image forming apparatus comprising: a duct which blows air toward both longitudinal ends of the heating member or the pressure applying member, the duct being arranged so as to be movable in a direction transverse to the longitudinal direction ; and an opening of an outlet which blows air from the duct gradually narrows in the longitudinal direction and in a direction perpendicular to the direction of movement of the duct, and widens in the longitudinal direction as the duct moves away from the heating member or the pressure applying member in the direction transverse to the longitudinal direction.

Images