JP7844934B2 - Image forming apparatus - Google Patents

Description

This invention relates to an image forming apparatus.

In electrophotographic image forming apparatuses, an airflow path is installed to cool the inside of the apparatus. This airflow path has an intake section, an exhaust section, or both. However, if the outer surface of the image forming apparatus where the intake or exhaust section is located is placed flush against a wall, the airflow path becomes blocked. Therefore, a technique is already known to create a recess in the outer surface of the image forming apparatus to prevent the airflow path from being blocked and to allow the air to escape to the bottom or sides.

For example, Patent Document 1 discloses a configuration in which openings are provided on the rear and bottom sides as exhaust openings for the purpose of dissipating heat from inside the aircraft.

Patent Document 1 presented a problem where, if the device was simultaneously placed against a wall on the back, left, and right sides, the exhaust airflow could not escape. Furthermore, even when employing a method that directs the exhaust airflow downwards, the limited space led to heat buildup. In particular, in the exhaust section, heat naturally rises, resulting in inadequate heat dissipation. While exhaust sections could be limited to the corners of the device, this configuration narrowed the range of heat dissipation, failing to effectively release heat from locations away from the corners. Thus, conventional technology has problems in efficiently dissipating heat from within the device, taking thermal properties into account.

The present invention aims to provide an image forming apparatus capable of efficiently exhausting heat compared to conventional designs.

The image forming apparatus according to the present invention is an image forming apparatus having an exhaust section for exhausting heat from inside the apparatus, wherein the exhaust section is provided on the side surface of the image forming apparatus and has a notched recess with an opening above the position where the heat is exhausted from the side surface, and the recess is formed as a depression by having a portion that protrudes from the bottom surface of the recess to the outside of the apparatus in the upper opening that forms the notch shape.

According to this invention, heat can be exhausted more efficiently than in conventional methods.

This is a perspective view showing the overall configuration of an image forming apparatus according to an embodiment of the present invention. Figure 1 is a cross-sectional view conceptually showing the internal structure of the image forming apparatus. This is a view from the direction of arrow A (rear side of the device body) in the schematic diagram of the device body (Figure 1). This is a cross-sectional view of the area around the fan where a notch has been cut out and recessed on the upper side. This figure shows an example of exhaust when there is a wall on the back side of the device. This figure shows an example where there is a recess above the duct or fan location, forming a recessed area without a notch. This diagram shows how a wall lower than the main unit of the device is positioned to block the duct. This figure shows an example where an outer cover is attached to the main body of the device, and the airflow of heat discharged from ducts and fans flows to the upper side of the main body of the device, with the filter being detachably positioned.

The embodiments of the present invention will now be described. The present invention has the following features in relation to a heat exhaust duct. In short, in an electrophotographic image forming apparatus, an airflow path is installed to cool the inside of the image forming apparatus. In a configuration where this airflow path has an exhaust section, if the outer surface of the image forming apparatus where the exhaust section is located is placed flush against a wall, the exhaust section becomes blocked. Therefore, the outer surface of the image forming apparatus is recessed to prevent the airflow path from being blocked, allowing the airflow to escape upwards. Furthermore, a key feature is that the duct is constructed so that the path extends from the exhaust surface to the upper surface, rather than having a diagonal recess at the corner. The features of the present invention described above will be explained in detail with reference to the following drawings.

Figure 1 is a perspective view showing the overall configuration of an image forming apparatus according to an embodiment of the present invention, and Figure 2 is a conceptual cross-sectional view showing the internal structure of the image forming apparatus shown in Figure 1.

The internal paper discharge type color copier 1 of this embodiment mainly consists of a roughly box-shaped device body 10 with an open top, which is the housing of the entire image forming apparatus; an image reading unit 2 located at the top of the device body 10 for reading the image of the original document; an image forming unit 3 located below the image reading unit 2 for forming an image based on the image information read by the image reading unit 2 or transmitted by an external device; a paper feeding unit 4 located at the very bottom of the device body 10 for supplying recording media P (hereinafter referred to as paper P) such as paper (referring to sheet-like materials including copy paper, resin sheets for OHP, cardboard, postcards, etc.; the same applies hereinafter); a paper discharge unit 5 located above the image forming unit 3 for discharging the paper P; and a paper transport path 6 located between the paper feeding unit 4 and the paper discharge unit 5.

The image reading unit 2 is mounted on the top surface of the main body 10 and consists of a contact glass 20 as a document tray on which the document is placed, a light source 21 positioned directly below the contact glass 20 that illuminates the document while moving, an imaging lens 22 that forms an image of the reflected light from the document, an image sensor 23 such as a CCD positioned at the imaging position to read the document image, and multiple mirrors that reflect the reflected light from the document and guide it to the imaging lens 22. Furthermore, a pressure plate 24 is provided above the image reading unit 2 to hold down the document placed on the contact glass 20 (shown in Figure 2; Figure 1 is omitted). Note that there is also a structure in which an automatic document feeder (ADF) is installed to automatically feed the document onto the contact glass 20 instead of the pressure plate 24, but this is well known and therefore not illustrated or described.

The image forming unit 3 consists of four process cartridges 3Y, 3M, 3C, and 3K corresponding to a total of four toner colors: yellow, magenta, cyan, and black; a writing unit 30 located below these four process cartridges 3Y, 3M, 3C, and 3K that writes latent images to each photosensitive drum; four toner bottles 31Y, 31M, 31C, and 31K that contain new toner of the colors corresponding to each process cartridge; a transfer unit 32 that transfers the images formed by each process cartridge to paper P; and a fixing unit 33 that fixes the image to paper P.

The process cartridges 3Y, 3M, 3C, and 3K are arranged along the lower surface of the intermediate transfer belt 32a (described later), in the order of yellow, magenta, cyan, and black, from the upstream side in the direction of movement of the outer peripheral surface indicated by the arrows in the figure. Each process cartridge 3Y, 3M, 3C, and 3K is an image-making device integrally molded and detachable from the main body 10. It consists of a charging means for uniformly charging the outer peripheral surface of each photoreceptor drum Y, M, C, and K (which rotates clockwise on the paper in Figure 2), a developing means 30Y, 30M, 30C, and 30K for visualizing the electrostatic latent image formed on each photoreceptor drum Y, M, C, and K by the writing unit 30 (described later) into a monochromatic toner image using the corresponding toners, and a cleaning means for cleaning and recovering residual toner remaining on the outer peripheral surface of the photoreceptor drums Y, M, C, and K after transfer.

The writing unit 30 is an exposure device equipped with a polygon mirror and an fθ lens, which scans the image information input from the image reading unit 2, a personal computer, an external scanner, etc., while irradiating it with laser light from a laser light emitter. It selectively exposes the outer surfaces of the uniformly charged photoreceptor drums Y, M, C, and K, lowering the surface potential of the irradiated areas and forming an electrostatic latent image on the photoreceptor drums.

The toner bottles 31Y, 31M, 31C, and 31K are each individually filled with the four colors of new toner, and the toner of each color is supplied to the developing means 30Y, 30M, 30C, and 30K of each process cartridge 3Y, 3M, 3C, and 3K via a transport path (not shown).

The transfer unit 32 is an intermediate transfer type transfer device mainly composed of an intermediate transfer belt 32a, which is an endless belt made of a multilayer structure of elastic resin as an intermediate transfer body; four support rollers 32b, 32c, 32d, and 32e that support and tension the intermediate transfer belt 32a; four primary transfer rollers 32f that face the photoreceptor drums Y, M, C, and K on either side of the intermediate transfer belt 32a; and a secondary transfer roller 32g positioned opposite the support rollers 32b.

The support roller 32b is a drive roller connected to a drive mechanism (not shown), and has the function of rotating the intermediate transfer belt 32a in the direction of the arrow in the figure. A secondary transfer roller 32g is positioned opposite the support roller 32b (hereinafter referred to as the drive roller 32b) across the intermediate transfer belt 32a. A cleaning device 32h is provided near the support roller 32c to scrape off residual toner adhering to the outer surface of the intermediate transfer belt 32a.

Each primary transfer roller 32f is a contact-type transfer bias (transfer voltage) application means, connected to a bias power supply (not shown), and configured to apply the primary transfer bias from the back surface (inner circumferential surface) of the intermediate transfer belt 32a. The position of each primary transfer roller 32f is determined considering image degradation due to air gap discharge. Specifically, they are positioned slightly downstream in the direction of surface movement of the intermediate transfer belt 32a, from the direct contact position where the centers of each photoreceptor drum Y, M, C, and K contact the intermediate transfer belt 32a at the shortest distance.

The secondary transfer roller 32g is biased by a biasing means (not shown) and presses against the intermediate transfer belt 32a on the outer circumference of the drive roller 32b, forming a secondary transfer nip between it and the drive roller 32b. The drive roller 32b is a contact-type transfer bias application means connected to a bias power supply (not shown). Alternatively, the secondary transfer roller 32g may also function as a transfer bias application means; in this case, a transfer bias with opposite polarity to the toner image being transferred would be applied.

The fixing unit 33 forms a fixing nip between the fixing belt 33c, which is an endless belt stretched between the fixing roller 33a and the heating roller 33b, and the pressure roller 33d, which acts as a pressurizing member that presses against the fixing belt 33c. In this fixing nip, heat and pressure are applied to the paper P that has been transported through the paper transport path 6 (described later), causing the toner image transferred in the secondary transfer nip of the transfer unit 32 to melt and adhere to the paper P, thereby fixing it in place.

The paper feeding unit 4 includes, for example, paper feed cassettes 40 and 41 capable of accommodating paper P of various sizes. The paper feed cassettes 40 and 41 are designed to be retractable from the main unit 10 and are equipped with paper feed rollers 42 and 43 that press against the stored paper P from above. Based on control signals from a control means (not shown), the paper P stored in the paper feed cassettes 40 and 41 are fed by the paper feed rollers 42 and 43 to the paper transport path 6, which will be described later.

Furthermore, the paper feeding unit 4 is equipped with a manual feed tray 44 for placing any paper within a predetermined size range that can be transported, and a paper feed roller 45 for feeding out this paper. The paper placed in the manual feed tray 44 can be fed to the paper transport path 6 (described later) by rotating the paper feed roller 45.

The paper discharge unit 5 includes a paper discharge tray 50 consisting of a slanted portion formed between the aforementioned toner bottles 31Y, 31M, 31C, and 31K and the image reading unit 2, followed by a flat portion. The paper P discharged from the paper discharge opening by the paper discharge roller pair 63 is then collected on the paper discharge tray 50. That is, the illustrated example is a so-called in-cylinder paper discharge type, but the present invention is not limited to image forming apparatuses having this type of paper discharge unit. This paper discharge unit is provided with means, described later, for dissipating the heat generated in the aforementioned image forming unit 3 (image-making unit).

The paper transport path 6 mainly consists of a normal transport path 60 that uses a vertical transport method (vertical pass method) to transport paper from the paper feeding section 4 located at the bottom of the main body 10 to the paper discharge section 5 located at the top of the main body 10, and a reverse transport path 61 that reverses the paper P for double-sided printing. These normal transport paths 60 and reverse transport paths 61 are equipped with multiple transport roller pairs at intervals corresponding to the minimum paper size, and these transport roller pairs rotate while gripping the paper P to transport it.

In addition to the transport roller pair, the normal transport path 60 is equipped with a registration roller pair 62 below the secondary transfer nip and a paper discharge roller pair 63 near the end in the paper transport direction. The registration roller pair 62 adjusts the timing of transporting the paper P to the secondary transfer nip of the transfer unit 32 based on commands from a control means (not shown), and then transfers the image to the paper P at the secondary transfer nip. Afterward, the paper P passes through the fixing unit 33 to fix the image, and is then discharged from the paper discharge port 64 onto the paper discharge tray 50 by the paper discharge roller pair 63.

The switching between the normal transport path 60 and the reverse transport path 61 is performed by the switching claw 65. For example, when the paper P guided by the switching claw 65 leaves the normal transport path 60, the reverse transport roller pair 66 carries it to the upper transport path 67 of the reverse transport path 61, and the reverse transport roller pair 66 reverses, flipping the leading and trailing ends of the paper P in a switchback manner. While transporting the paper P to the normal transport path 60 in front of the registration roller pair 62, the front and back sides of the paper P are reversed.

Next, the image forming operation of the illustrated color copier 1 will be described.
When making a copy, first open the pressure plate 24 (shown in Figure 2, not shown in Figure 1) and place the original document on the contact glass 20 of the image reading unit 2. If an ADF is provided instead of the pressure plate 24, place the original document on the ADF's platen. Next, when you press the start switch on the operation panel 71 or perform other operations, the image reading unit 2 is driven, and light emitted from the moving light source 21 strikes the surface of the original document and is reflected. This reflected light is then reflected by multiple mirrors and passed through the imaging lens 22 to form an image on the image sensor 23. The image sensor 23 converts this into an electronic signal and reads the image (content of the original document). If an ADF is installed, the original document is automatically transported from the ADF's mounting plate to the contact glass 20 before the above operation is performed. Then, depending on the mode setting selected on the operation panel, the image formation operation is performed in full color mode or black and white mode.

When forming a color image in full-color mode, when the image formation operation is started in the color copier 1, each photoreceptor drum Y, M, C, and K is rotated clockwise when viewed from the front of the color copier 1 (direction in Figure 1). At this time, the outer surfaces of each photoreceptor drum Y, M, C, and K are uniformly charged to a predetermined polarity (for example, negative) by each charging means. Then, laser light is irradiated onto each charged surface based on image information color-separated to correspond to the toner color from the writing unit 30, forming an electrostatic latent image on the outer surfaces of each photoreceptor drum Y, M, C, and K. Then, these electrostatic latent images are made visible as monochrome toner images by each developing means 30Y, 30M, 30C, and 30K, and a primary transfer bias is applied to each toner image of each color by the corresponding primary transfer roller 32f, and they are sequentially transferred onto the intermediate transfer belt 32a to form a full-color toner image. When forming a monochrome image in black and white mode, the above operation is performed using only the black process cartridge 3K.

Then, the paper P stored in the paper cassettes 40 and 41 of the paper feeding unit 4 is fed one sheet at a time into the paper transport path 6 by the paper feed rollers 42 and 43. The fed paper P rises up the paper transport path 6 and stops when its leading edge hits the registration roller pair 62. Even if the leading edge of the paper P is angled relative to the transport direction, this contact corrects it. Next, the registration roller pair 62 is rotated in sync with the timing when the color toner image formed on the intermediate transfer belt 32a reaches the secondary transfer nip, and the paper P is fed towards the secondary transfer nip of the transfer unit 32.

Next, a secondary transfer bias is applied at the secondary transfer nip of the transfer unit 32, and the full-color toner image on the intermediate transfer belt 32a is transferred to the paper P by electrostatic force. Afterward, the paper P is sent to the fuser nip of the fuser unit 33. There, heat and pressure are applied by the fuser belt 33c and pressure roller 33d, fixing the unfixed toner image on the paper P. After the toner image is fixed, the paper P is ejected onto the paper output tray 50 by the rotation of the paper output roller pair 63. When multiple sheets of paper P are ejected, they are stacked in the order of ejection, as shown in Figure 2.

Furthermore, when duplex mode is selected and duplex copying is performed, the transport path is switched by the switching claw 65, and the paper P with the image fixed on one side is temporarily stored in the upper transport path 67 of the reversal transport path 61. Then, the direction of travel is reversed in a switchback manner by the reversal transport roller pair 66, and the paper is transported along the reversal transport path 61 by the transport rollers, re-feeded in front of the registration roller pair 62, and image formation (printing) on the reverse side is performed in the same manner as the image formation operation described above.

Furthermore, residual toner on the photoreceptor drums Y, M, C, and K is cleaned by the respective cleaning means. Then, a bias with an AC component superimposed on DC is applied by the charging means, simultaneously discharging the photoreceptor drum and uniformly charging it. Additionally, residual toner on the intermediate transfer belt 32a is cleaned by the cleaning device 32h, preparing the color copier 1 for the next image forming operation.

Figure 3 is a view of the device body 10 from the direction of arrow A (rear side of the device body) in the schematic diagram of the device body 10 (Figure 1). A recess is provided around the fan 136 for exhausting heat from the device body 10, with a cutout on the upper side (above the fan 136). A cross-sectional view of this area is shown in Figure 4. To dissipate heat from inside the device, the fan 136 is rotated from the duct 137 to expel the heat from inside the device to the outside. If there are no obstacles on the back side (side A), the heat inside the device is discharged in a straight line as exhaust 508. In this embodiment, a cutout shape 138 is provided around the fan 136 on the back side of the device, in a part of the device body above the downstream heat exhaust flow path that discharges heat from inside the device to the outside. With this configuration, for example, even if there is a wall B on the back side of the device as shown in Figure 5, the heat discharged from inside the device is exhausted upward as exhaust 507 due to the cutout shape 138, and is not blocked by wall B.

In other words, in the device body 10, a notched recess is formed by a first exhaust surface 501 located at a horizontal position X2 at or near the same position below the lower end position X1 of the fan 136 on the downstream side in the heat exhaust direction, where heat is exhausted by the fan 136, and a second exhaust surface 502 extending upward (approximately vertically upward in this example) from both sides in the width direction of the first exhaust surface 501, which is a side surface for guiding the heat airflow exhausted from the fan 136 to the top of the first exhaust surface 501. The top of this recess is open. With this configuration, heat can be efficiently exhausted even if the back and sides of the device body 10 are blocked by a wall or the like. Conventionally, when heat with an upward characteristic is exhausted downward, the problem of heat accumulation and inability to dissipate properly occurs, but this problem can be resolved.

Furthermore, if the duct 137 and fan 136 are located at the bottom of the device body 10, the exhaust path can be secured by extending the notch shape 138 in the vertical direction of the device. In other words, the second exhaust surface 502 described above can be extended further upward. Thus, by having a notch shape with an opening on the upper side of the device body 10, taking into account the characteristic of heat rising, the heat inside the device can be efficiently exhausted.

Furthermore, as shown in Figure 6, another example will be described in which there is a recess above the position of the duct 137 and fan 136 provided at the exhaust port of the device body 10. Although the device body 10 has the above-mentioned recess, a portion 602 is formed above the recess, protruding from the bottom surface 503 of the recess toward the outer wall of the device, so a configuration like the recessed portion 601 without the aforementioned notch can be considered. With such a configuration, as shown in Figure 7, even if a wall 506 that is lower in height than the device body 10 is positioned to block the duct 137, heat can be exhausted 507 from a position that avoids that position. In other words, even if the first exhaust surface 501 described above is blocked by the wall 506 which is higher than the first exhaust surface 501, if the height of the wall 506 does not reach the upper end of the second exhaust surface 502 described above, heat can be exhausted from the open space 701 of the recessed portion 601 that is not blocked by the wall 506. In this example, the height of the upper surface of the wall 506 is approximately at the center of the recess 601 provided on the back surface of the device body 10. Even when heat is exhausted from the duct 137 and fan 136, which are located lower than this center, heat from inside the device can escape through the opening 701 in the recess 601 that is higher than the center and not covered by the wall 506.

Furthermore, as shown in Figure 8, consider a configuration where an outer cover 510 is attached to the main body 10 of the device, and the hot airflow discharged from the duct 137 and fan 136 flows to the upper side of the main body 10. In this case, a filter 509 is detachably placed at the opening on the upper side of the main body 10, which is the downstream side of the airflow, to filter out the airflow containing fine particles and dust discharged along with the exhausted heat. This allows the filter 509 to be removed in the direction C from the front side, opposite to the direction A shown in Figure 1, improving the ease of filter replacement.

As described above, the image forming apparatus in this embodiment is an image forming apparatus 1 (or apparatus body 10) having an exhaust section (e.g., fan 136, duct 137) for exhausting heat from inside the apparatus. The exhaust section is provided on the side of the image forming apparatus and has a notched recess (e.g., the notched section 138) with an opening above the position where the heat is exhausted from the side (e.g., the position of surface A shown in Figure 4). This configuration allows for efficient heat exhaust by considering the thermal characteristics of the apparatus.

Furthermore, the recessed portion includes a first exhaust surface (e.g., a first exhaust surface 501) positioned horizontally at the same or near-lower position as the lower end of the exhaust section, and a second exhaust surface (e.g., a second exhaust surface 502) extending upward from both sides in the width direction of the first exhaust surface, guiding the hot airflow exhausted from the exhaust section upwards to the first exhaust surface. This configuration allows the hot airflow exhausted from the fan 136 to be guided upwards without dispersion.

Furthermore, the upper opening that forms the notch shape has a portion (for example, the portion 602 shown in Figure 6) that protrudes outward from the bottom surface of the recess (for example, the bottom surface 503 of the recess shown in Figure 6), thereby forming the recess as a depression (for example, the depression 601 shown in Figure 6). With this configuration, even if there is a low wall (for example, wall 506) that covers part of the opening on the side of the device, heat can be exhausted from the space that is not covered by the opening (for example, the opening space 701).
Furthermore, a filter (for example, filter 509) for filtering the exhausted hot airflow is detachably provided in the upper opening that forms the cutout shape described above. With this configuration, the user can easily replace the filter from the front without having to go around to the rear of the device.

Furthermore, the recessed portion and the wall in contact with the surface of the image forming apparatus on the recessed portion side (for example, wall B shown in Figure 5) form a duct shape that guides the airflow of heat exhausted from the exhaust section. This configuration allows for more efficient heat exhaust by considering the thermal properties of the apparatus.

Furthermore, the duct shape is formed with a first exhaust surface (e.g., first exhaust surface 501) positioned horizontally at the same or near-lower position as the lower end of the exhaust section, and a second exhaust surface (e.g., second exhaust surface 502) extending upward from both sides in the width direction of the first exhaust surface, guiding the hot airflow exhausted from the exhaust section upwards to the first exhaust surface. This configuration allows for more reliable upward guidance of the hot airflow exhausted from the fan 136 without dispersion.

Conventionally, in technologies such as those described in Patent Document 1, an intake opening was formed between the lower surface of the slide tray that assists in loading sheets from the output tray and the slide opening, and the slide opening also served as the intake opening, resulting in a compact design. However, this configuration had the problem that the intake opening would be blocked if the image forming apparatus was installed flush against (or very close to) a wall. However, in the image forming apparatus with a recessed portion in this embodiment, the exhaust port is positioned so as not to be blocked even when in close proximity to a wall, and a recess is formed on the surface outside the image forming apparatus extending from the exhaust port toward the upper surface of the image forming apparatus. This reduces the deterioration of exhaust efficiency caused by the intake opening being blocked.

1 Color copier 2 Image reading unit 3 Image forming unit 4 Paper feeding unit 5 Paper discharge unit 6 Paper transport path 10 Device body 136 Fan 137 Duct 138 Notch shape 501 First exhaust surface 502 Second exhaust surface 509 Filter 601 Recess

Patent No. 3923709 specification

Claims (4)

An image forming apparatus having an exhaust unit for exhausting heat from inside the apparatus,
The exhaust section is provided on the side of the image forming apparatus ,
A notched recessed portion with an opening above the position from which the heat is exhausted from the side,
It has ,
An image forming apparatus characterized in that the upper opening that forms the notch shape has a portion that protrudes from the bottom surface of the recess to the outside of the apparatus, thereby forming the recess as a depression . The aforementioned recessed portion is,
A first exhaust surface is positioned at the same horizontal position as or near the lower end of the exhaust section,
A second exhaust surface extends upward from both sides in the width direction of the first exhaust surface and guides the hot airflow exhausted from the exhaust section to the upper part of the first exhaust surface,
The image forming apparatus according to claim 1, characterized by having the following features. The recessed portion and the wall in contact with the surface of the image forming apparatus on the recessed portion side form a duct shape that guides the airflow of heat exhausted from the exhaust portion.
The image forming apparatus according to feature 1. The aforementioned duct shape is,
The exhaust section is formed having a first exhaust surface positioned horizontally at the same or near the lower end position as the lower end of the exhaust section, and a second exhaust surface extending upward from both sides in the width direction of the first exhaust surface, which guides the hot airflow exhausted from the exhaust section to the upper part of the first exhaust surface.
The image forming apparatus according to feature 3 .