Image forming apparatus

Abstract

To improve productivity without increasing the size of the equipment. [Solution] The image forming apparatus (1A) comprises a housing (10) having an image forming installation section (10A) in which an image forming unit (513A) is installed, and a cassette installation section (10C) in which a plurality of cassettes for storing sheets are mounted and installed. The cassette installation section is equipped with a plurality of cassettes, including a first cassette (52b) capable of storing a first size sheet, a second cassette (52c) capable of storing a first size sheet and positioned on one side of the horizontal direction of the first cassette, and a third cassette (52a) capable of storing a second size sheet larger than the first size sheet and positioned on one side of the vertical direction of the first and second cassettes, wherein the average of the vertical heights of the first and second cassettes is three times or more the vertical height of the third cassette.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that forms an image on a sheet.

Background Art

[0002] In image forming apparatuses, a configuration has been proposed in which a plurality of decks for stacking and supporting sheets are arranged not only vertically below an image forming unit but also in the lateral (horizontal) direction, so as to increase the sheet stacking capacity while reducing the installation space of the apparatus (see Patent Document 1).

[0003] Further, in image forming apparatuses, a configuration has been proposed in which frame components are shared so that a sheet feeding device and a toner collecting device can be selectively attached to a frame, thereby achieving cost reduction (see Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0005] By the way, in an image forming apparatus, when a plurality of decks (cassettes) are arranged so as not to cause an increase in the size of the apparatus, it is necessary to arrange the plurality of decks (cassettes) in a certain amount of space, but an increase in the number of times sheets are replenished may lead to a decrease in productivity.

[0006] Accordingly, an object of the present disclosure is to provide an image forming apparatus capable of improving productivity without causing an increase in size.

[0007] However, the problems that the embodiments disclosed in this specification and drawings aim to solve are not limited to those described above. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0008] One aspect of the present invention is an image forming apparatus comprising a housing having an image forming unit on which an image forming unit for forming an image on a sheet is installed, and a cassette installation unit arranged on one side in the vertical direction of the image forming installation unit and on which a plurality of cassettes for storing sheets to be fed to the image forming unit are mounted, wherein the plurality of cassettes are installed in the cassette installation unit, the plurality of cassettes being installed, the first cassette being capable of storing a sheet of a first size to be fed to the image forming unit, the second cassette being capable of storing a sheet of the first size to be fed to the image forming unit and arranged on one side in the horizontal direction of the first cassette, and the third cassette being capable of storing a sheet of a second size larger than the first size to be fed to the image forming unit and arranged on one side in the vertical direction of the first cassette and the second cassette, and the average of the vertical heights of the first cassette and the second cassette is three times or more the vertical height of the third cassette. [Effects of the Invention]

[0009] According to the present invention, productivity can be improved without leading to an increase in size. [Brief explanation of the drawing]

[0010] [Figure 1] This is an overall schematic diagram showing a first type of image forming apparatus according to the first embodiment. [Figure 2] This is an overall schematic diagram showing a second type of image forming apparatus according to the first embodiment. [Figure 3] This is a perspective view showing the vertical path transport section. [Figure 4] This is a perspective view showing the feeding section. [Figure 5]This is a perspective view showing the vertical transport door. [Figure 6] This is a perspective view showing the main frame with the cassette feeding unit and vertical path transport unit attached. [Figure 7] (a) is a side view showing the main frame with the vertical path transport section and cassette feeding section removed. (b) is an enlarged view showing the coupling drive gear section. [Figure 8] This is an overall schematic diagram showing a second type of image forming apparatus according to the second embodiment. [Modes for carrying out the invention]

[0011] <First Embodiment> [Overall structure] The first embodiment will be described below. In this embodiment, a common housing 10 is used, that is, a first type image forming apparatus 1A and a second type image forming apparatus 1B using a main frame 100 as a common frame will be described. Figure 1 is an overall schematic diagram showing the first type image forming apparatus according to the first embodiment. Figure 2 is an overall schematic diagram showing the second type image forming apparatus according to the first embodiment.

[0012] The first type of image forming apparatus 1A is an electrophotographic monochrome laser beam printer that forms a monochrome (black and white) image on a recording material sheet based on image information read from a document or image information received from an external device. The second type of image forming apparatus 1B is an electrophotographic color laser beam printer that forms a color image on a recording material sheet based on image information read from a document or image information received from an external device. Sheets used as recording materials or documents include paper such as plain paper and cardboard, plastic films such as overhead projector sheets, cloth, surface-treated sheet materials such as coated paper, and specially shaped sheet materials such as envelopes and index paper.

[0013] (Type 1 image forming apparatus) First, the overall configuration of the first type of image forming apparatus 1A will be described. As shown in FIG. 1, the image forming apparatus 1A includes a housing 10 having a main body frame 100 inside. The housing 10 roughly has, as internal spaces, an image forming installation section 10A, a conveyance installation section 10B, a cassette installation section 10C, and a collection installation section 10D. The image forming apparatus 1A further includes a cassette feeding unit 51, an image forming section 513A, a collected toner storage device 580, a fixing device 23, a branch conveyance device 24, a reverse conveyance device 501, and a duplex conveyance device 502.

[0014] In the image forming installation section 10A of the housing 10, the image forming section 513A serving as a first image forming section is installed. In the conveyance installation section 10B of the housing 10, the fixing device 23, the branch conveyance device 24, the reverse conveyance device 501, and the duplex conveyance device 502 are installed. In the cassette installation section 10C of the housing 10, the cassette feeding unit 51 is installed. In the collection installation section 10D of the housing 10, the collected toner storage device 580 is installed. Note that toner removed from the photosensitive drum 508 and the intermediate transfer belt 506 is conveyed to the collected toner storage device 580 via a collected toner conveyance section (not illustrated).

[0015] The image forming section 513A that performs monochrome image formation includes an exposure device 511Bk, and a process cartridge 20Bk that forms a black (K) image.

[0016] The exposure device 511Bk irradiates laser light toward the photosensitive drum 508 of the process cartridge 20Bk based on input image information. At this time, the photosensitive drum 508 is pre-charged by a charger (not illustrated), and an electrostatic latent image is formed on the photosensitive drum 508 by being irradiated with the laser light. After that, the electrostatic latent image is developed by a photosensitive developing device 510, and a black (Bk) toner image is formed on the photosensitive drum 508.

[0017] The toner image formed on the photosensitive drum 508 is transferred to the intermediate transfer belt 506 by the primary transfer roller 507, and is conveyed to the secondary transfer inner roller 503 by the rotating intermediate transfer belt 506. Adherents such as residual transfer toner remaining on the photosensitive drum without being transferred to the intermediate transfer belt 506 are removed by a cleaner 509.

[0018] In parallel with the above-described image forming process, a sheet is fed from the cassette feeding unit 51 or the external receiving portion 555. The external receiving portion 555 is normally covered with an exterior cover or the like, and the cover is removed when, for example, an external large-capacity deck is connected to the image forming apparatus 1A. Then, the external receiving portion 555 receives a sheet fed from the large-capacity deck. As described above, when the loading capacity of the cassette incorporated in the image forming apparatus 1A alone is not sufficient to satisfy the user's printing work, the large-capacity deck is connected to the image forming apparatus 1A.

[0019] The cassette feeding unit 51 according to the present embodiment includes a cassette unit 51a having a large-size cassette 52a disposed at a lower position. Further, the cassette feeding unit 51 according to the present embodiment includes two cassette units 51b and 51c which are disposed above the cassette 52a and have small-size cassettes 52b and 52c arranged side by side in the horizontal direction. The sizes of these cassette units 51a, 51b, 51c (cassettes 52a, 52b, 52c) will be described later. That is, the cassette 52c is disposed on one side of the cassette 52b in the horizontal direction, and the cassette 52a is disposed on one side of the cassettes 52b and 52c in the vertical direction.

[0020] The lower-stage cassette unit 51a includes left and right guide rails 61a and 62a, a cassette 52a as a third cassette capable of storing sheets, and a feeding portion 53a as a third feeding portion configured to feed the sheets stored in the cassette 52a. The cassette 52a is supported by the guide rails 61a and 62a so as to be drawable.

[0021] The feeding unit 53a includes a pickup roller 54a that feeds out the top sheet from the cassette 52a, a feed roller 55a that receives and transports the sheet from the pickup roller 54a, and a retard roller 56a that contacts the feed roller 55a. A driving force in the opposite direction to the rotation of the feed roller 55a is input to the retard roller 56a via a torque limiter (not shown). The retard roller 56a applies a frictional force in the opposite direction to the feeding direction to the sheet entering the separation nip between the feed roller 55a and the retard roller 56a, thereby pushing back the sheets other than the top sheet to the cassette 52a.

[0022] The sheets, separated one by one from the cassette 52a by the feeding unit 53a, are transported along the vertical path 70, which serves as the first transport path, by the vertical path roller pair 71a, 71b, and 71c, and then handed over to the merging roller pair 5. That is, the vertical path 70 is arranged to extend vertically on the other side of the horizontal direction of the cassettes 52b and 52c, and transports the sheets toward the image forming unit 513A.

[0023] The vertical path roller pair 71a consists of a vertical path roller 57a provided by the feeding unit 53a and a driven roller 72a provided by the vertical path transport door 72 (described later) that rotates in conjunction with the vertical path roller 57a, which is the third transport roller. The vertical path roller pair 71b consists of a vertical path roller 77 provided by the vertical path transport unit 73 (described later) that is the second transport roller and a driven roller 72b provided by the vertical path transport door 72 (described later) that rotates in conjunction with the vertical path roller 77. The vertical path roller pair 71c consists of a vertical path roller 57b provided by the feeding unit 53b (described later) and a driven roller 72c provided by the vertical path transport door 72 (described later) that rotates in conjunction with the vertical path roller 57b.

[0024] The cassette unit 51b on the right side when viewed from the front of the upper section has left and right guide rails 61b and 62b, a cassette 52b as a first cassette capable of storing a sheet, and a feeding unit 53b as a first feeding unit for feeding the sheet contained in the cassette 52b. The cassette 52b is supported so as to be retractable by the guide rails 61b and 62b. The feeding unit 53b has a pickup roller 54b, a feed roller 55b, and a retard roller 56b, but since it has the same configuration as the feeding unit 53a described above, a detailed explanation is omitted.

[0025] The sheets, separated one by one from the cassette 52b by the feeding unit 53b and fed, are transported by the vertical path roller pair 71c, which acts as the first transport roller, along the vertical path 70, and then handed over to the merging roller pair 5.

[0026] Furthermore, the cassette unit 51c on the left side when viewed from the front of the upper section has left and right guide rails 61c and 62c, a cassette 52c as a second cassette capable of storing a sheet, and a feeding unit 53c as a second feeding unit that feeds the sheet contained in cassette 52c. Cassette 52c is supported so as to be retractable by the guide rails 61c and 62c. The feeding unit 53c also has a pickup roller 54c, a feed roller 55c, and a retard roller 56c, but since it has the same configuration as the feeding units 53a and 53b described above, a detailed explanation will be omitted.

[0027] The sheets, separated one by one from the cassette 52c by the feeding unit 53c and fed, are transported along the relay path 75 and the double-sided path 502p, which serves as the second transport path, by the relay path roller pair 58 and the transport roller pairs 502b, 502a, and then handed over to the merging roller pair 5.

[0028] The relay pass roller pair 58 is composed of a drive roller 57c provided by the feeding unit 53c and a driven roller 58a provided by the feeding unit 53c that rotates in accordance with the drive roller 57c.

[0029] The feeding sections 53a, 53b, and 53c described above are merely examples of sheet feeding devices. For example, an air feeding system may be used in which the top sheet is attracted to a belt by sucking in air and then fed. In addition, a pad-shaped friction member may be used instead of a retard roller as a separating member to separate the fed sheets one by one.

[0030] The sheets sent from the cassette feeding unit 51 or the external receiving unit 555 are transported to the registration roller pair 7 after passing through the merging roller pair 5 and the pre-registration roller pair 6. The sheets are corrected for skew by the registration roller pair 7 and transported at a predetermined transport timing. For example, the sheets are temporarily accelerated by the registration roller pair 7, and then decelerated when the sheet detection sensor 8 detects the leading edge of the sheet. In this way, the timing of the sheets is adjusted so that the image formation position of the sheet matches the toner image formed on the intermediate transfer belt 506.

[0031] Then, the toner image on the intermediate transfer belt 506 is transferred to the sheet by the secondary transfer inner roller 503 and the secondary transfer outer roller 21. Any remaining toner or other deposits on the intermediate transfer belt 506 that were not transferred to the sheet are removed by the belt cleaner 515. The sheet onto which the toner image has been transferred is transported by the belt conveyor 22, and in the fixing device 23, predetermined heat and pressure are applied to melt and fix the toner. The sheet that has passed through the fixing device 23 is discharged outside the machine by the branching conveyor 24 and loaded onto the discharge tray 500.

[0032] When forming an image on both sides of a sheet, the sheet, with an image formed on the first side and having passed through the fixing device 23, is transported to the reversing transport device 501 by the branching transport device 24. The sheet is then reversed in its transport direction by the reversing transport device 501 through a switchback transport. The sheet, with its transport direction reversed, is transported along the double-sided path 502p of the double-sided transport device 502 by transport roller pairs 502d, 502c, 502b, and 502a, and then re-transported to the registration roller pair 7. As a result, the sheet is transported with its front and back reversed so that the second side, opposite to the first side, faces the intermediate transfer belt 506, and the toner image is transferred to the second side by the secondary transfer inner roller 503 and the secondary transfer outer roller 21.

[0033] The image forming unit 513A provided in the image forming apparatus 1A of this embodiment is an example of an image forming unit that forms an image on a sheet. As other image forming units, for example, an electrophotographic unit using a direct transfer method that transfers a toner image from a photoreceptor to a sheet without passing through an intermediate transfer medium may be used. In addition, an image forming unit other than an electrophotographic method may be used, such as an inkjet type image forming unit or an offset printing type printing mechanism.

[0034] (Type 2 image forming apparatus) Next, the second type of image forming apparatus 1B will be described using Figure 2. Figure 2 is an overall schematic diagram showing the second type of image forming apparatus according to the first embodiment.

[0035] The second type of image forming apparatus 1B is modified by replacing the monochrome image forming unit 513A in the first type of image forming apparatus 1A with a color image forming unit 513B. In other words, the image forming apparatus 1B is an electrophotographic color laser beam printer that forms a color image on a sheet used as a recording material based on image information read from a document or image information received from an external device.

[0036] More specifically, an image forming unit 513B, which serves as a second image forming unit, is installed in the image forming installation section 10A of the housing 10. The image forming unit 513B includes exposure devices 511Y, 511M, 511C, and 511Bk, and four process cartridges 20Y, 20M, 20C, and 20Bk that form images of four colors: yellow (Y), magenta (M), cyan (C), and black (K). The four process cartridges 20Y to 20Bk have a common configuration except for the different colors of the images they form. Note that the process cartridges 20Y to 20Bk have the same configuration as the process cartridge 20Bk in the monochrome image forming unit 513A described above, so the explanation of process cartridges 20Y, 20M, and 20C will be omitted.

[0037] When forming an image, toner images of yellow (Y), magenta (M), cyan (C), and black (K) are formed on the photosensitive drums of process cartridges 20Y, 20M, 20C, and 20Bk. The toner images of each color formed on each photosensitive drum are transferred to the intermediate transfer belt 506 by the primary transfer roller 507, and a full-color toner image is formed on the intermediate transfer belt 506. The image formation process for each color is performed at a timing that overlaps with the upstream toner image that has been primary transferred onto the intermediate transfer belt 506. The full-color toner image on the intermediate transfer belt 506 is then transported to the secondary transfer inner roller 503, and as described above, it is transferred to the sheet transported from the cassette feeding unit 51 by the secondary transfer inner roller 503 and the secondary transfer outer roller 21.

[0038] The sheet onto which the toner image has been transferred is transported by the belt conveyor 22, and in the fixing device 23, predetermined heat and pressure are applied to melt and fix the toner. The sheet that has passed through the fixing device 23 is discharged outside the machine by the branching conveyor 24 and loaded onto the discharge tray 500. Other operations (for example, operations such as double-sided printing) are the same as those of the first type image forming apparatus 1A described above, so their explanation will be omitted.

[0039] (Commonality between Type 1 and Type 2 image forming apparatuses) The first type image forming apparatus 1A and the second type image forming apparatus 1B described above have the monochrome image forming unit 513A and the color image forming unit 513B swapped, and the structure of the housing 10 and the main frame 100 are standardized to reduce costs.

[0040] In other words, the monochrome image forming unit 513A can be made smaller than the color image forming unit 513B by eliminating the intermediate transfer belt 506 (a so-called direct transfer method), similar to, for example, Japanese Patent Publication No. 9-20434. However, considering the recent increase in demand for color machines and the decrease in demand for monochrome machines, in the future, the commonality of parts between monochrome and color machines must be promoted not only at the individual component level, but also at the level of commonality of the housing 10 and the main body frame 100.

[0041] In this embodiment, in order to standardize the structure of the housing 10 and the main frame 100, the image forming installation section 10A, which serves as an internal space, is of a common size. Therefore, the cassette installation section 10C is also of a common size, and it is necessary to design this cassette installation section 10C, which is limited in size, appropriately to meet the user's requirements.

[0042] On the other hand, in recent years, the demand for B-series paper sizes (B5, B4, etc.) used in printers has been limited to a small portion of the market, while the proportion of A-series paper, particularly A4 size (small size), has increased significantly. Furthermore, there is a certain demand for A3 size (large size) for creating explanatory materials and the like. Therefore, in this embodiment described below, we propose a configuration in the cassette installation section 10C consisting of two small-size (corresponding to A4 size) cassettes and one large-size (corresponding to A3 size) cassette. This addresses the increasing demand for A4 size in recent years, accommodates A3 size, and efficiently utilizes the space for storing sheets.

[0043] (Cassette details) In the image forming apparatus 1A or 1B of this embodiment, the loading capacity (i.e., the number of sheets that can be loaded) of A4 size (small size) as the first size to be set inside the image forming apparatus is increased without changing the size of the housing 10. Furthermore, the loading capacity of the image forming apparatus 1A or 1B is suitable for setting A3 size (large size) as the second size as well. When replenishing sheets, it is possible to set one commonly available pack (500 sheets) at once.

[0044] In other words, conventionally, many image forming apparatuses are configured as shown in Japanese Patent Publication No. 9-20434, which generally consists of two large-size cassettes and two small-size cassettes. However, in the present invention, the large-size cassette is configured as a single unit, or in other words, one of the large-size cassettes is eliminated, thereby increasing the loading capacity of the two small-size cassettes. Specifically, this reduces the size of one cassette (including approximately 60 mm for the loading height), the size of the feeding section (parts around the pickup roller, sheet transport detection section, sheet presence / absence detection section, feeding frame, etc., not shown), and the gap between adjacent cassettes vertically. As a result, the loading height of one large-size cassette (approximately 60 mm) and the space occupied by other parts (approximately 20 mm or more) are reduced. Therefore, as shown in Figures 1 and 2, the height of the loading capacity (hereinafter referred to as "loading height") H1b and H1c of the two small-sized cassettes, cassettes 52b and 52c, could be set to approximately 186 mm.

[0045] In summary, in the image forming apparatus 1A or image forming apparatus 1B according to this embodiment, the small-size cassettes 52b and 52c are configured with a loading height H1b and H1c of approximately 186 mm. The large-size cassette 52a is configured with a loading height H2a of approximately 60 mm. The loading capacity of the sheets of the small-size cassettes 52b and 52c and the large-size cassette 52a can be expressed in a ratio of approximately 3 to 1. Specifically, the small-size cassettes 52b and 52c are 186 mm to 60 mm (3.1 to 1) in height compared to the large-size cassette 52a, meaning they are more than three times taller.

[0046] In general, most commercially available sheets come in packs of 500. This number is said to be suitable for use, not too heavy to carry, and a convenient number. Therefore, packs of 500 sheets are the most common and widely available product.

[0047] Furthermore, by allowing an entire pack of sheets to be loaded at once during replenishment, it is possible to eliminate the problem of leftover sheets that cannot be loaded. In other words, it is known that sheets begin to absorb moisture once they have been removed from the pack. Moreover, if leftover sheets are stored improperly, they will absorb even more moisture. As moisture absorption progresses, it may lead to deterioration of the sheet shape, such as curling or wavyness. And deterioration of the sheet shape can cause paper jams. In addition, uneven moisture absorption inside the sheet and a decrease in the sheet's performance may lead to problems when toner is transferred to the sheet. Therefore, in this embodiment, the aim is to reduce the causes of paper jams and image defects by allowing an entire pack of sheets (500 sheets) to be loaded at once when replenishing cassettes 52a, 52b, and 52c.

[0048] Furthermore, while high-capacity cassettes with a high stacking height, such as large-capacity decks, can accommodate a large number of sheets (packs) at once, they also increase the depth of the cassette. This could lead to incorrect sheet placement for users unfamiliar with replenishing sheets. Additionally, a large number of sheets are inherently heavy, increasing the impact during insertion and removal, thus requiring increased rigidity of the sheet feeding unit and cassette. Moreover, the increased impact during cassette insertion could cause vibration in the image forming unit, potentially leading to image defects. For these reasons, the image forming apparatus 1A and 1B according to this embodiment are designed to supply approximately 3 to 4 packs of sheets to a single cassette 52b or 52c mounted within the housing 10.

[0049] For the reasons explained above, in the image forming apparatus 1A and 1B according to this embodiment, the loading capacity of the large-size cassette 52a is the same as in the conventional design, and it is designed to hold 500 sheets in one pack. The loading capacity of the small-size cassettes 52b and 52c is designed to hold 1500 sheets in three packs.

[0050] In reality, the number of sheets that can be loaded into a cassette depends on the sheet's basis weight, which in turn depends on its thickness. For example, a sheet with a basis weight of 80 GSM has a thickness of 0.105 mm. Therefore, the loading capacity of the large-size cassette, cassette 52a, is approximately 570 sheets (60 mm / 0.105 mm), while the loading capacity of the small-size cassettes, cassettes 52b and 52c, is approximately 1770 sheets (186 mm / 0.105 mm). If one pack contains 500 sheets, then the loading capacity of the large-size cassette, cassette 52a, is 1 pack and 70 sheets, and the loading capacity of the small-size cassettes, cassettes 52b and 52c, is 3 packs and 270 sheets.

[0051] Furthermore, for example, with a sheet of 64 GSM basis weight, the thickness of one sheet is 0.089 mm. Therefore, the loading capacity of the large-size cassette, cassette 52a, is approximately 670 sheets (60 mm / 0.089 mm), and the loading capacity of the small-size cassettes, cassettes 52b and 52c, is approximately 2080 sheets (186 mm / 0.089 mm). If one pack contains 500 sheets, then the loading capacity of the large-size cassette, cassette 52a, is 1 pack and 170 sheets, and the loading capacity of the small-size cassettes, cassettes 52b and 52c, is 4 packs and 80 sheets.

[0052] As described above, the number of sheets (packs) that can be loaded into each cassette will differ depending on the type of sheet, such as differences in basis weight. However, the loading capacity (volume) of cassettes 52b and 52c remains the same. Therefore, when fully loaded, the load weight will be the same, so there is no need to increase the rigidity of the cassette just because you are loading sheets with a larger basis weight.

[0053] [Vertical pass surrounding configuration] Next, the configuration surrounding the vertical path 70 shown in Figures 1 and 2 will be explained using Figures 3 to 5. Figure 3 is a perspective view showing the vertical path transport section. Figure 4 is a perspective view showing the feeding section. Figure 5 is a perspective view showing the vertical path transport door.

[0054] As shown in Figures 1 and 2, the image forming apparatuses 1A and 1B have a vertical path 70 that guides the sheets fed from the cassette units 51a and 51b so that they are transported upward. On the outside of the vertical path 70, as shown in Figures 1, 2, and 5, a vertical path transport door 72 is provided as a door. The vertical path transport door 72 is provided so as to be openable and closable relative to the housing 10 of the image forming apparatuses 1A and 1B by upper and lower hinges 74a and 74b.

[0055] Furthermore, driven rollers 72a, 72b, and 72c are rotatably supported in the vertical path transport door 72. The vertical path transport door 72 has a guide surface 72G, which serves as a fourth guide section and, when closed relative to the housing 10, constitutes at least a part of the guide surface on the outside (one horizontal side) of the vertical path 70. The vertical path transport door 72 is configured to allow a user or service technician to access the vertical path 70 when opened relative to the housing 10. This makes it easy to replace jams and rollers, improving maintainability. Above the feeding section 53a of the image forming apparatus 1A and 1B, and to the side of the cassette unit 51b, a vertical path transport section 73 and a transport guide 78 are provided as transport sections. The feeding section 53a, the vertical path transport section 73, and the feeding section 53b are each provided with vertical path rollers 57a, 77, and 57b that face the driven rollers 72a, 72b, and 72c, respectively.

[0056] The driven rollers 72a, 72b, and 72c are configured to rotate in accordance with the vertical path rollers 57a, 77, and 57b, respectively. That is, the driven roller 72b can grip and transport the sheet together with the vertical path roller 77. As shown in Figure 3, the vertical path transport section 73 has a guide surface 73G that guides the sheet by forming at least a part of the vertical path 70, and mounting parts 73F and 73R provided at the front and rear ends of the device, respectively. In addition, a drive gear 79 for inputting the driving force of the vertical path roller 77 is fixed to one end of the rotation axis of the vertical path roller 77.

[0057] On the other hand, as shown in Figures 1 and 2, the feeding sections 53a and 53b of the cassette units 51a and 51b are provided with vertical pass rollers 57a and 57b that face the driven rollers 72a and 72c. Of these, the driven roller 72a is configured to rotate in accordance with the vertical pass roller 57a. In other words, the driven roller 72a can grip and transport the sheet together with the vertical pass roller 57a. Also, the driven roller 72c is configured to rotate in accordance with the vertical pass roller 57b. In other words, the driven roller 72c can grip and transport the sheet together with the vertical pass roller 57b.

[0058] As shown in Figure 4, the feeding sections 53a and 53b have guide surfaces 53aG and 53bG that guide the sheet by forming at least a part of the vertical path 70, and mounting sections 53F and 53R provided at the front and rear ends of the device, respectively. In addition, drive gears 59a and 59b for inputting the driving force of the vertical path rollers 57a and 57b are fixed to one end of the rotation axis of the vertical path rollers 57a and 57b. In this embodiment, the guide surface 53bG constitutes the first guide section, the guide surface 53aG constitutes the third guide section, and the guide surface 73G constitutes the second guide section.

[0059] [Attachment to frame] Next, the attachment of the feed unit 53a, the vertical path transport unit 73, and the feed unit 53b to the common main frame 100 of the image forming apparatus 1A and 1B will be explained using Figures 6 and 7. Figure 6 is a perspective view showing the frame with the cassette feed unit and the vertical path transport unit attached. (a) is a side view showing the main frame with the vertical path transport unit and the cassette feed unit removed. (b) is an enlarged view showing the coupling drive gear.

[0060] (Mounting structure) As shown in Figure 6, the main frame 100 has engaging portions 75a and 75b that engage with the hinge portions 74a and 74b of the vertical path transport door 72. The main frame 100 also has mounting portions 111a, 111b, and 111c provided on the front side of the device, and mounting portions 110a, 110b, and 110c provided on the rear side of the device. In this embodiment, mounting portions 111c and 110c, arranged in order from top to bottom, constitute the first mounting portion, mounting portions 111b and 110b constitute the second mounting portion, and mounting portions 111a and 110a constitute the third mounting portion.

[0061] The mounting portion 53aF of the feeding portion 53a is attached to the mounting portion 111a, and the mounting portion 53aR of the feeding portion 53a is attached to the mounting portion 110a. Positioning bosses are provided on the mounting portions 111a and 110a, respectively, and the mounting portions 53aF and 53aR are inserted into positioning holes formed in the mounting portions 53aF and 53aR by the positioning bosses and fastened together with screws. In this way, the feeding portion 53a is positioned and fixed to the main frame 100. In this embodiment, the mounting portions 53aF and 53aR constitute a third mounting portion.

[0062] Similarly, the mounting portion 73F of the vertical path conveying unit 73 is attached to the mounting portion 111b, and the mounting portion 73R of the vertical path conveying unit 73 is attached to the mounting portion 110b. Positioning bosses are provided on the mounting portions 111b and 110b, respectively, and the mounting portions 73F and 73R are inserted into positioning holes formed in the mounting portions 73F and 73R by the positioning bosses and fastened together with screws. In this way, the vertical path conveying unit 73 is positioned and fixed to the main frame 100. In this embodiment, the mounting portions 73F and 73R constitute the second mounting portion.

[0063] Similarly, the mounting portion 53bF of the feeding portion 53b is attached to the mounting portion 111c, and the mounting portion 53bR of the feeding portion 53b is attached to the mounting portion 110c. Positioning bosses are provided on the mounting portions 111a and 110a, respectively, and the mounting portions 53bF and 53bR are inserted into positioning holes formed in the mounting portions 53bF and 53bR by the positioning bosses and fastened together with screws. In this way, the feeding portion 53b is positioned and fixed to the main frame 100. In this embodiment, the mounting portions 53bF and 53bR constitute the first mounting portion.

[0064] Furthermore, the mounting sections 111a, 111b, and 111c provided on the front side of the device and the mounting sections 110a, 110b, and 110c provided on the rear side of the device are all configured in the same way, that is, they are configured to the same specifications. Similarly, the mounting sections 53aF, 73F, and 53bF and mounting sections 53aR, 73R, and 53bR of the feeding section 53a, vertical path transport section 73, and feeding section 53b are all configured in the same way, that is, they are configured to the same specifications. As a result, the feeding sections 53a, 53b and the vertical path transport section 73 can be mounted at any of the three vertical positions on the main frame 110, in other words, their positions can be swapped. Therefore, as shown in the second embodiment described in detail later, the mounting position of the feeding sections 53a and 53b on the main frame 100 can be changed without changing the configuration of the main frame 100 or the configuration of the feeding sections 53a and 53b.

[0065] Furthermore, the vertical path transport door 72 is equipped with driven rollers 72c, 72b, and 72a arranged in order from top to bottom, and the driven rollers 72c, 72b, and 72a are all constructed in a similar manner, that is, to the same specifications. Similarly, the vertical path roller 57a of the feeding section 53a, the vertical path roller 77 of the vertical path transport section 73, and the vertical path roller 57b of the feeding section 53b are all constructed in a similar manner, that is, to the same specifications. As a result, these driven rollers 72c, 72b, and 72a can contact the vertical path roller 57a of the feeding section 53a, the vertical path roller 77 of the vertical path transport section 73, and the vertical path roller 57b of the feeding section 53b, regardless of which of the three mounting positions the feeding section 53a, the vertical path transport section 73, and the feeding section 53b are mounted in. Therefore, without changing the design of the main frame 100 or the housing 10, it is possible to attach the feeding unit 53a, the vertical path transport unit 73, and the feeding unit 53b, each constituting the vertical path 70, to any of the three mounting locations, and the mounting position can be changed.

[0066] Furthermore, the transport guide 78 (see Figures 1 and 2) provided above the vertical path transport section 73 is provided to adjust the height space when the feeding section 53b is positioned above the vertical path transport section 73. In other words, in this embodiment, because the large-sized cassette is arranged in a single layer, the cassettes 52b and 52c are larger in the vertical direction and are larger in the vertical direction than the vertical path transport section 73, so the transport guide 78 is provided to prevent the sheet from deviating from the vertical path 70.

[0067] (Drive coupling configuration) Furthermore, as shown in Figures 7(a) and 7(b), the main frame 100 has connecting drive gears 117a, 117b, and 117c arranged vertically within the housing 10 so as to be rotatable. These connecting drive gears 117a, 117b, and 117c are connected to a drive motor (not shown) and output driving force to the drive gear 59a of the feeding unit 53a, the drive gear 79 of the vertical path conveying unit 73, and the drive gear 59b of the feeding unit 53b.

[0068] Specifically, when the mounting parts 53aF and 53aR of the feeding unit 53a are attached to the mounting parts 111a and 110a, the coupling drive gear 117a meshes with the drive gear 59a of the feeding unit 53a to drive and connect them. Also, when the mounting parts 73F and 73R of the vertical path conveying unit 73 are attached to the mounting parts 111b and 110b, the coupling drive gear 117b meshes with the drive gear 79 of the vertical path conveying unit 73 to drive and connect them. Furthermore, when the mounting parts 53bF and 53bR of the feeding unit 53b are attached to the mounting parts 111c and 110c, the coupling drive gear 117c meshes with the drive gear 59b of the feeding unit 53b to drive and connect them.

[0069] The driving force input from the linked drive gears 117a and 117c to the feeding sections 53a and 53b drives the pickup roller, feed roller, retard roller, and vertical pass roller in each feeding section, and also drives the lift-up mechanism inside the cassette. The lift-up mechanism inside cassette 52a and the lift-up mechanism inside cassette 52b are different mechanisms, but the specifications of the drive gears 59a and 95b to which the driving force is input are common.

[0070] In other words, the coupling drive gears 117a, 117b, and 117c are all configured in a similar manner, that is, to the same specifications, so as to mesh with the drive gears 59a and 59b of the feeding sections 53a and 53b and the drive gear 79 of the vertical path conveying section 73, respectively. In this embodiment, the coupling drive gear 117c, arranged in order from top to bottom, constitutes the first drive output section, the coupling drive gear 117b constitutes the second drive output section, and the coupling drive gear 117a constitutes the third drive output section. Furthermore, the drive gear 59b of the feeding section 53b constitutes the first drive input section, the drive gear 79 of the vertical path conveying section 73 constitutes the second drive input section, and the drive gear 59a of the feeding section 53a constitutes the third drive input section.

[0071] In short, the drive gear 59a of the feeding unit 53a can be driven to the connecting drive gear 117a when the mounting parts 53aF and 53aR of the feeding unit 53a are attached to the mounting parts 111a and 110a. Furthermore, the drive gear 59a can be driven to the connecting drive gear 117b when the mounting parts 53aF and 53aR of the feeding unit 53a are attached to the mounting parts 111b and 110b. In addition, the drive gear 59a can be driven to the connecting drive gear 117c when the mounting parts 53aF and 53aR of the feeding unit 53a are attached to the mounting parts 111c and 110c.

[0072] Similarly, the drive gear 79 of the vertical path conveying unit 73 can be driven and connected to the coupling drive gear 117b when the mounting parts 73F and 73R of the vertical path conveying unit 73 are attached to the mounting parts 111b and 110b. Furthermore, the drive gear 79 can be driven and connected to the coupling drive gear 117a when the mounting parts 73F and 73R of the vertical path conveying unit 73 are attached to the mounting parts 111a and 110a. In addition, the drive gear 79 can be driven and connected to the coupling drive gear 117c when the mounting parts 73F and 73R of the vertical path conveying unit 73 are attached to the mounting parts 111c and 110c.

[0073] Similarly, the drive gear 59b of the feeding unit 53b can be driven to the connecting drive gear 117b when the mounting parts 53bF and 53bR of the feeding unit 53b are attached to the mounting parts 111b and 110b. The drive gear 59b can also be driven to the connecting drive gear 117a when the mounting parts 53bF and 53bR of the feeding unit 53b are attached to the mounting parts 111a and 110a. Furthermore, the drive gear 59b can also be driven to the connecting drive gear 117c when the mounting parts 53bF and 53bR of the feeding unit 53b are attached to the mounting parts 111c and 110c.

[0074] As described above, the coupling drive gears 117a, 117b, and 117c, the drive gears 59a and 59b of the feeding sections 53a and 53b, and the drive gear 79 of the vertical path transport section 73 are all configured to a common standard that allows them to be driven and coupled regardless of which of the three mounting positions they are installed in. This makes it possible to replace the feeding section and the vertical path transport section, eliminating the need to design image forming machines specifically for each type, and thus enabling overall cost reduction.

[0075] [Summary of the First Embodiment] As described above, in the image forming apparatus 1A and 1B according to this embodiment, two small-sized cassettes 52b and 52c are installed on the left and right sides of the cassette installation section 10C of the housing 10, and one large-sized cassette 52a is installed below them. The vertical height (i.e., loading capacity) of the small-sized cassettes 52b and 52c is more than three times the vertical height (i.e., loading capacity) of the large-sized cassette 52a. This allows the cassette 52a to meet the demand for A3-sized sheets, while the cassettes 52b and 52c can meet the increasing demand for A4-sized sheets. Therefore, by arranging the cassettes 52a, 52b, and 52c in the cassette installation section 10C of the common housing 10, it is possible to reduce the number of times A4-sized sheets, which are in high demand from users, need to be replenished without increasing the overall size, thereby improving productivity.

[0076] Furthermore, in the image forming apparatus 1A and 1B according to this embodiment, the loading capacity of cassettes 52b and 52c is set to be 3 times or more, rather than a multiple including a decimal point, such as 2.5 times the loading capacity of cassette 52a. In other words, by setting it to be a multiple of a natural number or more, when replenishing sheets, it is possible to replenish one to three packs (500 sheets) at once, with one pack being treated as one unit, in any cassette. This prevents the generation of leftover sheets when a pack is opened, and reduces the causes of paper jams and image defects.

[0077] In this first embodiment, we described a configuration in which the small-sized cassettes 52b and 52c have the same loading capacity, and each has at least three times the capacity of the large-sized cassette 52a. However, as described in the second embodiment later, the small-sized cassettes 52b and 52c may have different loading capacities, and their average is at least three times (totaling at least six times). This also reduces the number of times A4-sized sheets, which are in high demand among users, need to be replenished, thereby improving productivity. Furthermore, if the average loading capacity of cassettes 52b and 52c is at least three times, all six packs can be replenished to cassettes 52b and 52c at once, thus preventing the occurrence of leftover sheets when a pack is opened.

[0078] Furthermore, in the image forming apparatus 1A and 1B according to this embodiment, the feeding unit 53c feeds the sheets from cassette 52c to the double-sided path 502p, and the sheets are transported to the image forming units 513A and 513B via the double-sided path 502p. As a result, when transporting the sheets from cassette 52c to the image forming units 513A and 513B, it is not necessary to form a transport path (transport route) that bypasses cassette 52b (see, for example, the horizontal transport path 512p in Figure 8). Therefore, it is not necessary to reduce the vertical height of cassette 52b, and a reduction in the loading capacity of cassette 52b can be prevented. In addition, since cassettes 52b and 52c can be constructed of the same size as in this embodiment, parts can be standardized, and costs can be reduced.

[0079] Furthermore, in the image forming apparatus 1A and 1B according to this embodiment, the main frame 100 has three mounting parts 110c, 111c, 110b, 111b, and 110a, 111a arranged in order from top to bottom. In addition, the feed unit 53a, the vertical path transport unit 73, and the feed unit 53b can be attached to any of the mounting parts in the vertical direction. In the image forming apparatus 1A and 1B according to this embodiment, the feed unit 53b is attached to the mounting parts 110c and 111c, the vertical path transport unit 73 is attached to the mounting parts 110b and 111b, and the feed unit 53a is attached to the mounting parts 110a and 111a. This makes it possible to form a vertical path 70 while arranging a large-size cassette 52a on the lower stage and a small-size cassette 52b on the upper stage. Furthermore, because the three mounting points arranged vertically are standardized, the arrangement of the cassette and vertical path transport section can be freely changed without redesigning the system. For this reason, for example, the image forming apparatus 1C of the second embodiment, which will be described later, can also be constructed without changing the design of the main frame 100 or the housing 10.

[0080] Furthermore, in the image forming apparatus 1A and 1B according to this embodiment, the housing 10 is equipped with coupling drive gears 117c, 117b, and 117a arranged in order from top to bottom. These coupling drive gears 117c, 117b, and 117a can be driven and connected to the drive gear 59a of the feed unit 53a, the drive gear 79 of the vertical path transport unit 73, and the drive gear 59b of the feed unit 53b, regardless of which of the three mounting locations the feed unit 53a, the vertical path transport unit 73, and the feed unit 53b are mounted to. Therefore, it is possible to mount the feed unit 53a, the vertical path transport unit 73, and the feed unit 53b to any of the three mounting locations without changing the design of the main frame 100 or the housing 10.

[0081] Furthermore, in the image forming apparatus 1A and 1B according to this embodiment, the vertical path transport door 72 is equipped with driven rollers 72c, 72b, and 72a arranged in order from top to bottom. These driven rollers 72c, 72b, and 72a can contact the vertical path roller 57a of the feed unit 53a, the vertical path roller 77 of the vertical path transport unit 73, and the vertical path roller 57b of the feed unit 53b, regardless of which of the three mounting positions the feed unit 53a, the vertical path transport unit 73, and the feed unit 53b are mounted to. Therefore, without changing the design of the main frame 100 or the housing 10, it is possible to mount the feed unit 53a, the vertical path transport unit 73, and the feed unit 53b, each constituting the vertical path 70, to any of the three mounting positions.

[0082] Furthermore, in the image forming apparatuses 1A and 1B according to this embodiment, one of the following can be selectively installed in the image forming installation section 10A: an image forming unit 513A that forms a monochrome image on a sheet, and an image forming unit 513B that forms a color image on a sheet. This allows the first type image forming apparatus 1A and the second type image forming apparatus 1B to use a common housing 10, and the main body frame 100 can also be standardized, thereby reducing costs.

[0083] <Second Embodiment> Next, a second embodiment, which is a modified version of the first embodiment described above, will be explained with reference to Figure 8. Figure 8 is an overall schematic diagram showing a second type of image forming apparatus according to the second embodiment. In this explanation of the second embodiment, the same reference numerals are used for parts similar to those in the first embodiment, and their explanations are omitted.

[0084] In the third type of image forming apparatus 1C according to this second embodiment, cassette units 51b and 51c, each having two small-size cassettes, cassettes 52b and 52c, arranged side by side, are positioned on the lower level. That is, in the image forming apparatus 1C, a cassette unit 51a having one large-size cassette, cassette 52a, is positioned on the upper level, and cassette units 51b and 51c are positioned below it. Furthermore, in the image forming apparatus 1C, a horizontal transport device 512 having a horizontal transport path 512p as a third transport path is positioned so as to pass between the cassette units 51a and 51b in the vertical direction. The horizontal transport device 512 has transport roller pairs 512b and 512a that transport sheets on the horizontal transport path 512p.

[0085] In the image forming apparatus 1C, sheets separated one by one from the cassette unit 51c are transported along the horizontal transport path 512p by the transport roller pair 512b and 512a, the orientation of the sheets is changed by the transport guide 512G, and then they are transported to the vertical path 70. The sheets transported to the vertical path 70 are then handed over to the merging roller pair 5. Other operations in the image forming apparatus 1C are the same as those in the image forming apparatus 1B described above, so their explanation is omitted.

[0086] In the image forming apparatus 1C, a horizontal transport device 512 is installed, so the loading height H4b of the right cassette 52b and the loading height H5c of the left cassette 52c are different, meaning their loading capacities are different.

[0087] In the image forming apparatus 1C according to the second embodiment, the loading height H3a of the large cassette, cassette 52a, will be expressed as a ratio of the sheet loading capacity (height), similar to the first embodiment. In the image forming apparatus 1C according to the second embodiment, the ratio of the average of the loading capacity (loading height H4b) of the right cassette 52b and the loading capacity (loading height H5c) of the left cassette 52c to the loading capacity (loading height H3c) of cassette 52a is approximately 3 to 1. That is, the average of the vertical heights of cassettes 52b and 52c is more than three times the vertical height of cassette 52a.

[0088] Specifically, the average loading height of cassette 52c (H5c, 180mm) and cassette 52b (H4b, 155mm) is 167.5mm (=(180+155) / 2). If cassette 52a has a loading height of H3a (55mm), the ratio becomes 167.5mm to 60mm (3.05 to 1).

[0089] For example, with a sheet weight of 80 GSM, the thickness of each sheet is 0.105 mm. Therefore, the storage capacity of the large-size cassette 52a is approximately 520 sheets (55 mm / 0.105 mm). The small-size cassette 52b has a capacity of approximately 1470 sheets (155 mm / 0.105 mm), and the small-size cassette 52c has a capacity of approximately 1710 sheets (180 mm / 0.105 mm). If one pack contains 500 sheets, the storage capacity of cassette 52a is 1 pack and 20 sheets, and the combined storage capacity of the two cassettes 52b and 52c is 6 packs and 180 sheets.

[0090] Furthermore, for example, a sheet with a basis weight of 64 GSM has a sheet thickness of 0.089 mm per sheet. The large-size cassette, cassette 52a, has a storage capacity of approximately 610 sheets (60 mm / 0.089 mm). The small-size cassette, cassette 52b, has a storage capacity of approximately 1740 sheets (155 mm / 0.089 mm), and the small-size cassette, cassette 52c, has a storage capacity of approximately 2020 sheets (180 mm / 0.089 mm). If one pack contains 500 sheets, the storage capacity of cassette 52a is 1 pack and 110 sheets, and the combined storage capacity of the two cassettes 52b and 52c is 7 packs and 260 sheets.

[0091] In the image forming apparatus 1C according to the second embodiment, the left and right small-size cassettes, cassettes 52b and 52c, are positioned near the bottom plate of the housing 10 in a location with high rigidity. Therefore, the overall rigidity design of the housing 10 and the main frame 100 is advantageous compared to the image forming apparatuses 1A and 1B of the first embodiment. In other words, the arrangement of the two small-size cassettes 52b and 52c and the one large-size cassette 52a can be determined by considering the design requirements such as the overall rigidity of the housing 10 and the main frame 100.

[0092] Furthermore, although the image forming apparatus 1C according to this second embodiment was described as having a color image forming unit 513B as an example, a monochrome image forming unit 513A may also be installed in the image forming installation unit 10A.

[0093] Furthermore, in the image forming apparatus 1C according to this second embodiment, a cassette 52b that is taller than cassette 52a is placed in the lower section. For this reason, the feeding unit 53a that feeds the sheets of cassette 52a is attached to the mounting sections 110c and 111c, and the feeding unit 53b that feeds the sheets of cassette 52b is attached to the mounting sections 110b and 111b (see Figure 6). Also, since there are no cassettes below cassette 52b, there is no need to attach the vertical path transport unit 73 to the mounting sections 110a and 111a, and nothing is attached to them.

[0094] In summary, the image forming apparatus 1C according to this second embodiment differs from the image forming apparatuses 1A and 1B of the first embodiment in that the height of the cassettes 52b and 52c is changed due to the addition of the horizontal transport device 512. However, because the cassettes 52b and 52c with larger loading capacity are placed in the lower section, this is advantageous in terms of the overall rigidity of the housing 10 and the main frame 100. Furthermore, because the cassettes 52b and 52c with larger loading capacity are placed in the lower section, the installation of the vertical path transport section 73 can be eliminated.

[0095] Furthermore, the configuration, operation, and effects of the second embodiment other than those described above are the same as those of the first embodiment, so their description will be omitted.

[0096] <Possibility of other embodiments> In the first and second embodiments described above, a system was described in which a monochrome image forming unit 513A and a color image forming unit 513B can be selectively installed in the image forming installation unit 10A, but the system is not limited to this. In other words, any type of image forming unit can be installed, and the size of the image forming apparatus can be changed accordingly. For example, the monochrome image forming unit 513A can be configured as a direct transfer type image forming unit without an intermediate transfer belt 506, and the image forming apparatus can be miniaturized by miniaturizing the monochrome image forming unit and the image forming installation unit 10A. Even with such a configuration, by making the average loading capacity of the small-sized cassettes 52b and 52c more than three times the loading capacity of the large-sized cassette 52a, it is possible to reduce the number of times small-sized (A4 size) cassettes are replenished as requested by the user.

[0097] Furthermore, in the first and second embodiments, a configuration was described in which the image forming unit 10A (image forming unit) is positioned above and the cassette unit 10C (multiple cassettes) is positioned below, but the invention is not limited to this configuration. Conversely, the image forming unit 10A may be positioned below and the cassette unit 10C may be positioned above.

[0098] Furthermore, in the first and second embodiments, the small-size cassette was described as storing A4-sized sheets, and the large-size cassette as storing A3-sized sheets. However, this is not limited to this configuration. For example, if a user requests a system that can store both B4 and B5-sized sheets, it is conceivable to arrange multiple cassettes in this manner. In particular, for users who have a greater demand for smaller-sized sheets than for larger-sized sheets, it is conceivable to make the average loading capacity of the small-size cassettes 52b and 52c more than three times the loading capacity of the large-size cassette 52a.

[0099] Furthermore, although Figure 8 shows a configuration in the second embodiment in which the vertical path transport door 72 is equipped with driven rollers 72a, the system is not limited to this configuration, and it is also acceptable to omit the driven rollers 72a. In this case, the other components can be standardized simply by not attaching the driven rollers 72a to the vertical path transport door 72. [Explanation of Symbols]

[0100] 1A...Image forming apparatus / 1B...Image forming apparatus / 1C...Image forming apparatus / 10...Housing / 10A...Image forming installation section / 10C...Cassette installation section / 52a...Cassette (3rd cassette) / 52b...Cassette (1st cassette) / 52c...Cassette (2nd cassette) / 53a...Feeding section (3rd feeding section) / 53aF...Mounting section (3rd mounting section) / 53aG...Guide surface (3rd guide section) / 53aR...Mounting section (3rd mounting section) / 53b...Feeding section (1st feeding section) / 53bF...Mounting part (first mounting part) / 53bG...Guide surface (first guide part) / 53bR...Mounting part (first mounting part) / 53c...Feeding part (second feeding part) / 57a...Vertical path roller (third conveying roller) / 57b...Vertical path roller (first conveying roller) / 59a...Connecting gear (third drive input part) / 59b...Connecting gear (first drive input part) / 70...Vertical path (first conveying path) / 72...Vertical path conveying door (door part) / 72a...Driven roller (third roller) / 72b...Driven roller (2nd roller) / 72c...Driven roller (1st roller) / 72G...Guide surface (4th guide part) / 73...Vertical path conveying part (conveying part) / 73F...Mounting part (2nd mounting part) / 73G...Guide surface (2nd guide part) / 73R...Mounting part (2nd mounting part) / 77...Vertical path roller (2nd conveying roller) / 79...Connecting gear (2nd drive input part) / 100...Main frame (frame) / 110a...Mounting part (3rd mounting part) / 110b...Mounting part (2nd mounting part) / 110c...Mounting Attachment part (first mounting part) / 111a...Mounting part (third mounting part) / 111b...Mounting part (second mounting part) / 111c...Mounting part (first mounting part) / 117a...Rotating drive gear (third drive output part) / 117b...Rotating drive gear (second drive output part) / 117c...Rotating drive gear (first drive output part) / 502p...Double-sided path (second transport path) / 512p...Horizontal transport path (third transport path) / 513A...Image forming unit (first image forming unit) / 513B...Image forming unit (second image forming unit)

Claims

1. The housing comprises an image forming installation section where an image forming unit for forming an image on a sheet is installed, and a cassette installation section located on one side in the vertical direction of the image forming installation section, on which a plurality of cassettes for storing sheets to be fed to the image forming unit are mounted and installed. The cassette installation section contains, as the plurality of cassettes, A sheet to be fed to the image forming unit, a first cassette capable of storing a sheet of a first size, A second cassette is provided to the image forming unit, which is capable of storing the first size sheet and is located on one of the horizontal sides of the first cassette, A third cassette is provided, which is capable of storing a sheet of a second size that is larger than the first size sheet, and which is located in one of the vertical directions of the first cassette and the second cassette, and is supplied to the image forming unit. The average of the vertical heights of the first and second cassettes is three times or more the vertical height of the third cassette. An image forming apparatus characterized by the following features.

2. The third cassette is located below the first and second cassettes. The image forming apparatus according to feature 1.

3. The vertical heights of the first and second cassettes are each at least three times the vertical height of the third cassette. The image forming apparatus according to feature 2.

4. A first feeding unit that feeds the sheet stored in the first cassette, A second feeding unit that feeds the sheet stored in the second cassette, A third feeding unit that feeds the sheet stored in the third cassette, A first transport path is arranged in the other direction of the first cassette and the third cassette so as to extend in the vertical direction, and transports the sheet toward the image forming unit, The system includes a second transport path positioned above the first and second cassettes so as to extend horizontally, which transports the sheet on which an image has been formed on its first surface in the image forming unit toward the image forming unit, The first feeding unit and the third feeding unit feed the sheet onto the first transport path, The second feeding unit feeds the sheet into the second transport path. The image forming apparatus according to feature 2.

5. A conveying unit that conveys the sheet along the first conveying path, The frame comprises a first mounting portion, a second mounting portion, and a third mounting portion arranged in order from top to bottom, The first feeding unit has a first guide unit that forms a part of the first transport path, and a first mounting unit that can be attached to any of the first to third mounting units. The transport unit has a second guide unit that forms a part of the first transport path, and a second attachment unit that can be attached to any of the first to third attachment units. The third feeding section has a third guide section that forms part of the first transport path, and a third mounting section that can be attached to any of the first to third mounting sections. The first mounting portion is attached to the first mounting portion, the second mounting portion is attached to the second mounting portion, and the third mounting portion is attached to the third mounting portion, thereby attaching the first feeding portion, the transport portion, and the third feeding portion to the frame in order from top to bottom, and forming the first transport path. The image forming apparatus according to feature 4.

6. The housing comprises a first drive output unit, a second drive output unit, and a third drive output unit, which are arranged in order from top to bottom within the housing and output driving force. The first feeding unit has a first drive input unit that can be driven to the first drive output unit when the first mounting unit is attached to the first mounting unit, to the second drive output unit when the first mounting unit is attached to the second mounting unit, and to the third drive output unit when the first mounting unit is attached to the third mounting unit. The transport unit has a second drive input unit that can be driven to the first drive output unit when the second mounting unit is attached to the first mounting unit, to the second drive output unit when the second mounting unit is attached to the second mounting unit, and to the third drive output unit when the second mounting unit is attached to the third mounting unit. The third feeding unit has a third drive input unit that can be driven to the first drive output unit when the third mounting unit is attached to the first mounting unit, to the second drive output unit when the third mounting unit is attached to the second mounting unit, and to the third drive output unit when the third mounting unit is attached to the third mounting unit. The image forming apparatus according to feature 5.

7. It has a first roller, a second roller, and a third roller arranged in order from top to bottom, and a fourth guide section that forms part of the first transport path, and is equipped with a door section that can be opened and closed relative to the housing, The first feeding unit has a first conveyor roller that, when the door is closed to the housing, contacts the first roller when the first mounting portion is attached to the first mounting portion, contacts the second roller when the first mounting portion is attached to the second mounting portion, and contacts the third roller when the first mounting portion is attached to the third mounting portion to convey the sheet. The transport unit has a second transport roller that transports the sheet when the door is closed to the housing and the second mounting portion is attached to the first mounting portion, the second mounting portion is attached to the second mounting portion, the third mounting portion is attached to the third mounting portion, and the second transport roller contacts the first roller. The second feeding unit has a third conveyor roller that, when the door is closed to the housing, contacts the first roller when the third mounting portion is attached to the first mounting portion, contacts the second roller when the third mounting portion is attached to the second mounting portion, and contacts the third roller when the third mounting portion is attached to the third mounting portion to convey the sheet. The image forming apparatus according to feature 5.

8. The third cassette is positioned above the first and second cassettes, The image forming apparatus according to feature 1.

9. The vertical height of the first cassette is less than three times the vertical height of the third cassette. The vertical height of the second cassette is greater than three times the vertical height of the third cassette. The image forming apparatus according to feature 8.

10. A first feeding unit that feeds the sheet stored in the first cassette, A second feeding unit that feeds the sheet stored in the second cassette, A third feeding unit that feeds the sheet stored in the third cassette, A first transport path is arranged in the other direction of the first cassette and the third cassette so as to extend in the vertical direction, and transports the sheet toward the image forming unit, The system includes a third transport path positioned above the first cassette and below the third cassette, extending horizontally, for transporting the sheet toward the image forming unit, The first feeding unit and the third feeding unit feed the sheet onto the first transport path, The second feeding unit feeds the sheet to the third transport path. The image forming apparatus according to feature 9.

11. The frame comprises a first mounting portion, a second mounting portion, and a third mounting portion arranged in order from top to bottom, The first feeding unit has a first guide unit that forms a part of the first transport path, and a first mounting unit that can be attached to any of the first to third mounting units. The third feeding section has a third guide section that forms part of the first transport path, and a third mounting section that can be attached to any of the first to third mounting sections. The third mounting portion is attached to the first mounting portion, and the first mounting portion is attached to the second mounting portion, thereby attaching the third feeding portion and the first feeding portion to the frame in order from top to bottom, and forming the first transport path. The image forming apparatus according to feature 10.

12. The housing comprises a first drive output unit, a second drive output unit, and a third drive output unit, which are arranged in order from top to bottom within the housing and output driving force. The first feeding unit has a first drive input unit that can be driven to the first drive output unit when the first mounting unit is attached to the first mounting unit, to the second drive output unit when the first mounting unit is attached to the second mounting unit, and to the third drive output unit when the first mounting unit is attached to the third mounting unit. The third feeding unit has a third drive input unit that can be driven to the first drive output unit when the third mounting unit is attached to the first mounting unit, to the second drive output unit when the third mounting unit is attached to the second mounting unit, and to the third drive output unit when the third mounting unit is attached to the third mounting unit. The image forming apparatus according to feature 11.

13. It has a first roller, a second roller, and a third roller arranged in order from top to bottom, and a fourth guide section that forms part of the first transport path, and is equipped with a door section that can be opened and closed relative to the housing, The first feeding unit has a first conveyor roller that, when the door is closed to the housing, contacts the first roller when the first mounting portion is attached to the first mounting portion, contacts the second roller when the first mounting portion is attached to the second mounting portion, and contacts the third roller when the first mounting portion is attached to the third mounting portion to convey the sheet. The second feeding unit has a third conveyor roller that, when the door is closed to the housing, contacts the first roller when the third mounting portion is attached to the first mounting portion, contacts the second roller when the third mounting portion is attached to the second mounting portion, and contacts the third roller when the third mounting portion is attached to the third mounting portion to convey the sheet. The image forming apparatus according to feature 11.

14. The image forming unit can be selectively configured to include either a first image forming unit that forms a monochrome image on the sheet or a second image forming unit that forms a color image on the sheet. The image forming apparatus according to feature 1.

15. The cassette installation section is located below the image forming installation section. The image forming apparatus according to feature 1.

16. The first size sheet is an A4 size sheet, The second size sheet is an A3 size sheet. The image forming apparatus according to feature 1.

Images