Image forming apparatus

Abstract: An image forming apparatus comprising functional components secured by a resin apparatus body which is in the form of mutual separable an upper casing (24) at least monocock structured and a lower casing (25).

Description: The present invention relates to an electrostatic duplicating machine or a printer of the type in which a latent electrostatic image is formed on a photoreceptor, a toner image is developed on the photoreceptor and then transferred onto a sheet. The United States Patent US-A-4,335,950 discloses a reproducing apparatus including a frame assembly made up of upper and lower molded plastic frame members, each frame member having sheet guiding elements integrally molded therein. The frame members are pivotally mounted relative to each other in clam shell fashion at one end. When the frame members are in closed position, they are securely positioned by co-operating datum points. The U.K. patent application GB-A-2,177,976 discloses an imaging apparatus for developing a latent image by means of a developing device using a toner cartridge. The body of the apparatus comprises an upper part and a lower part hinged to one another in clam shell fashion. A positioning frame member is supported by the lower body of the apparatus to be rotatable upwardly and downwardly. The positioning frame member supports an image carrier unit and a developing unit. The Japanese patent publication JP-A-2,215,666 discloses a document feeder for an image forming device comprising a housing body formed as a monocoque structure which serves both as a body frame and as an exterior. The monocoque structure is formed of thermoplastic resin. The monocoque body of the document feeder is connected to the copying machine body by hinge means which enable the feeder to be opened and closed relative to the copying machine. An image forming apparatus of the portable type having a minimized size is disclosed in the Japanese Examined Patent Publication JP-B-2-17453. This type of image forming apparatus comprises at least the following functional components: an exposing means for forming a latent electrostatic image on a photosensitive means; an image forming means for developing the latent electrostatic image formed on the photosensitive means into a toner image and transferring the toner image onto a sheet; a sheet transfer means for transferring the sheet into an apparatus body and discharging the sheet from the image forming means, where the sheet transfer means include a fixing means for fixing the toner image transferred on the sheet; a drive means for driving the transfer means; and electrical equipments. The above-mentioned functional components are mounted on a reinforcing metal frame consisting of a pair of side plates, stay members connecting the side plates, and other parts which are disposed in a box-shaped resin casing. In order to popularize the image forming apparatus having the above-mentioned construction for home or personal use, it is desirable that the apparatus should be made as compact and light as possible and the manufacturing cost and the selling price should be as inexpensive as possible. However, the conventional image forming apparatus necessitates the reinforcing frame for mounting the above-mentioned functional components, so that the amount of components tends to increase. The above fact also results in the problems of less compact and light-weight designs as well as expensive manufacturing costs of the apparatus. Furthermore, this requires the process of mounting the reinforcing frame to the apparatus, which results in further increasing the manufacturing cost. As the compact and light-weight designing is promoted, the image forming apparatus can be made handy for any person, but the possibility of excessive impact onto the apparatus increases, e.g. hitting against an object or dropping the apparatus. When such the excessive impact is applied to the apparatus, it tends to receive damage such as crack formation or plastic deformation particularly at the connecting portions between the apparatus body and the reinforcing frame because of the difference in material and strength. Although it would be possible to eliminate the reinforcing frame in view of the above problems, such an arrangement would reduce rigidity of the apparatus body. Therefore, for the functional components, the application of external force to the apparatus would be a significant factor which would have never arisen in conventional constructions. Particularly an image forming apparatus having a compact and light-weight design is based on the concept of popularizing the apparatus for home or personal use, so that maintenance of the apparatus should be carried out not by the service personnel but by the user himself or herself. However, when any functional component of the apparatus malfunctions, e.g. caused by the external force, it is virtually impossible for the user to cope with the malfunction by the user himself or herself owning to the lack of technical knowledge. Taking the above-mentioned facts into consideration, it will be an important factor to prevent the possible influence of an external force on functional components in a portable type image forming apparatus. Accordingly, present invention is proposed in view of the above-mentioned conventional problems with the object to provide an image forming apparatus which necessitates no reinforcing frame to achieve a compact and light-weight design, whereby the possible influence of an external force to the functional components of the apparatus is reduced. According to the present invention, an image forming apparatus is provided as defined in claim 1. These and other objects and advantages of the present invention will be more fully apparent from the detailed description of embodiments set forth below when taken in conjunction with the drawings in which: Fig. 1 is a perspective view of a duplicating machine provided as an image forming apparatus in accordance with an embodiment of the present invention; Fig. 2 is a section view of the duplicating machine; Fig. 3 is an exploded section view of the duplicating machine; Fig. 4 is an exploded perspective view of an upper casing of the duplicating machine; Fig. 5 is a section view of a portion of the upper casing; Fig. 6 is a bottom view of the upper casing in which functional components are supported; Fig. 7 is a perspective view of a lower casing of the duplicating machine; Fig. 8 is a section view of a portion of an engagement portion between the upper and lower casings in the embodiment; Fig. 9 is a perspective view of a sheet inlet tray to be mounted on the upper casing with a part thereof removed; Fig. 10 is a section view of a portion of the sheet inlet tray; Fig. 11 is a perspective view of the lower casing in which the sheet inlet tray and a sheet outlet tray are mounted; Fig. 12 is a plan view of the lower casing in which the sheet inlet tray and the sheet outlet tray are mounted; Fig. 13 is a perspective view of the sheet inlet tray with a portion thereof removed in accordance with another embodiment of the present invention; Fig. 14 is a plan view of the lower casing in accordance with the embodiment in Fig. 12; Fig. 15 is a plan view of a functional component belonging to the embodiment in Fig. 1; Fig. 16 is an expanded side view of a portion of a construction where an image transfer charger is attached to a functional component in Fig. 15; Fig. 17 is an expanded rear view of a portion of a construction where the image transfer charger is attached to the functional component in Fig. 15; Fig. 18 is an expanded section view of a portion of another construction of mounting the image transfer charger; Fig. 19 is an exploded perspective view of a functional component in accordance with another embodiment of the present invention; Fig. 20 is a perspective view of an assembled state of the functional component in Fig. 19; Fig. 21 is a schematic view of a toner collecting vessel in accordance with another embodiment of the present invention; Fig. 22 is an expanded section view of a portion of an image forming apparatus in accordance with another embodiment of the present invention; Fig. 23 is a section view of an embodiment of the present invention provided with an air outlet duct; Fig. 24 is a plan view of the body of the embodiment in Fig. 23 with a portion thereof removed; Fig. 25 is a schematic section view of the body of the embodiment in Fig. 23; Fig. 26 is a plan view of the body of another embodiment of the present invention with a part thereof removed; Fig. 27 is a schematic section view of the body of the embodiment in Fig. 26; Fig. 28 is a schematic section view of the body of another embodiment of the present invention; Fig. 29 is a schematic section view of the body of another embodiment of the present invention; Fig. 30 is a schematic section view of the body of another embodiment of the present invention; Fig. 31 is a plan view of the body of another embodiment of the present invention with a portion thereof removed; Fig. 32 is a schematic section view of the body of the embodiment in Fig. 31; Fig. 33 is a schematic section view of the body of another embodiment of the present invention; Fig. 34 is a schematic section view of the body of another embodiment of the present invention; Fig. 35 is a plan view of the body of another embodiment of the present invention with a portion thereof removed; Fig. 36 is a schematic section view of the body of the embodiment in Fig. 35; Fig. 37 is a schematic section view of the body of another embodiment of the present invention; and Fig. 38 is a schematic section view of the body of another embodiment of the present invention. Firstly referring to Fig. 1, a duplicating machine in accordance with an embodiment of the present invention is is shown as a so-called table moving type. A document placed on an document table 1 or a transparent glass plate is scanned under illumination by moving the document table 1 laterally in Fig. 2. Above the document table 1 is a pivotal document presser 11 for pressing the document placed on the document table 1, which is capable of being opened. Referring to Figs. 2 and 3, the body 2 is mutually separable into an upper casing 24 and a lower casing 25 which are made of a resin material and are coupled by screw means. Mounted in the machine body 2 formed by the upper casing 24 and the lower casing 25 are functional components such as exposing means 3, image forming means 4, sheet transfer means 5, fixing means 6, and drive means 7 (refer to Fig. 6), and electrical equipments 8 (refer to Fig. 6). Referring to Figs. 2 and 3, the exposing means 3 for scanning an illuminated document moved by the document table 1 comprise an optical unit housing 33 in which functional components are mounted. A rod-shaped fluorescent lamp 31 is arranged horizontally for illuminating the document and a rod lens 32 is provided for conducting reflection light from the original to the image forming means 4. The optical unit housing 33 is fixed to the upper casing 24 of the machine body 2 by screws, so that the exposing means 3 is entirely mounted in the upper casing 24. The image forming means 4 comprises functional components which include a photoreceptor 42 for holding the latent electrostatic image of the document, an electrostatic charger 43, an image developing unit 41, an image transfer charger 44, and a cleaner 45 around the photoreceptor 42. The electrostatic charger 43 is mounted via the optical unit housing 33 in the upper casing 24. On the other hand, the image developing unit 41, the photoreceptor 42, the image transfer charger 44, and the cleaner 45 are mounted in an image forming unit frame 46 fixed to the upper casing 24 by screw means so as to form a unit. Firstly a document image from the exposing means is focused on an outer peripheral surface of the photoreceptor 42 charged evenly by the electrostatic charger 43 to form a latent electrostatic image. Secondly the latent electrostatic image is developed into a toner image by the image developing unit 41. Thirdly the toner image is transferred onto a sheet by the image transfer charger 44, and then the remaining toner on the photoreceptor is collected by the cleaner 45. Describing the upper casing 24 of the machine body 2 with reference to Fig. 4, the upper casing 24 is provided with an upper surface formed with a slit 24c for scanning a document under illumination. A groove 24i is provided for mounting a slider S (refer to Fig. 5) movably supporting one end of the document table 1, and a ridge 24j for supporting the other end of the document table 1. The upper casing 24 has a side wall intersecting with end walls of the upper casing 24. The side wall is formed with an opening 24b into which a toner cartridge 41c (refer to Figs. 2 and 3) is drawably inserted. Opening 24b is covered with a cover 24g in an engagement manner. The the upper casing 24 has inner walls on which is formed a pair of guide plates 24d extending downward for guiding the toner cartridge 41c. The guide plates 24d are simultaneously so integrated with the upper casing 24 as to extend horizontally by a length almost equal to the entire length of the toner cartridge 41c (refer to Fig. 6). As described above, the toner cartridge 41c can be put into or out of the opening 24b of the upper casing 24 to permit easy replacement of the toner cartridge 41c without opening the interior of the machine body 2. Furthermore, since the guide plates 24d for insertion or extraction of the toner cartridge 41c are integrated with the upper casing 24, there is no need to provide a guide independently. This reduces the number of components and simplifies the production process leading to manufacturing cost reduction. Referring to Figs. 2 and 3, the upper casing 24 has a lower section which forms a lid section 24e. The lid section 24e is formed at a portion corresponding to a toner collecting vessel 47 as described in detail hereinafter to cover the upper opening of the vessel. The lid section 24e consists of the ceiling surface of the upper casing 24 and a downward rib 24f extending from the ceiling surface. By covering the toner collecting vessel 47 with the downward rib 24f abutting to the edge of the upper opening of the toner collecting vessel 47, toner collected in the toner collecting vessel 47 is prevented from spattering. Rims 47d are formed at the four corners of the toner collecting vessel 47. By putting screws 47e (refer to Figs. 2 and 3) through the rims 47d, the lid section 24e is put in close contact with the toner collecting vessel 47. Because lid section 24e is integrated with the upper casing 24 in the present embodiment, there is no need to provide an independent lid for the toner collecting vessel 47. This permits reducing the number of components leading to manufacturing cost reduction. The upper casing 24 is of a monocoque construction having four side walls and the ceiling panel serving as an exterior cover. The guide plates 24d and downward ribs, such as the downward rib 24f, provide that the desired rigidity can be achieved. Referring to Figs. 2, 3, and 7, the lower casing 25 has an inner bottom formed with plural lower guide ribs 25a for guiding the bottom surface of a transferred sheet. Provided in the bottom of the lower casing 25 is an opening 25b in which a support member 25d pivotally supported by a supporting point 25c. The support member 25d is made of a resin mold material, and an upper surface of the support member 25d is integrally formed with a plurality of parallel lower guide ribs 25e for guiding the bottom surface of the transferred sheet. By turning the support member 25d around the supporting point 25c clockwise in Fig. 2, the bottom section of the lower casing 25 and therefore a portion of the sheet transfer path can be opened for easy maintenance such as jammed sheet removal or the like. Referring to Fig. 7, the lower casing 25 is of monocoque construction having a rib-like upward section 25f along the peripheral edge of the opening 25b, four side walls and the bottom panel serving as an exterior cover. Upward ribs, such as the lower guide ribs 25a, provide for the desired rigidity. As described above, because the lower guide ribs 25a for guiding the lower surface of a sheet are integrated with the lower casing 25, there is no need to form the lower guide ribs 25a independently. This permits reducing the number of components and, therefore, no assembling process of the lower guide ribs 25a is required thereby reducing manufacturing cost. In order to integrate the upper casing 24 with the lower casing 25, at least the four corners of each of the casings 24 and 25 are formed with connecting portions 24k (refer to Fig. 6) and connecting portions 25h (refer to Fig. 7). The casings 24 and 25 are coupled by means of screws (not shown) through the connecting portions 24k and 25h. Because the upper casing 24 is coupled with the lower casing 25 at least at the four corners thereof, even when the casing 24 or the casing 25 is deformed, the casings are securely coupled correcting the deformation. In more detail, if the upper casing 24 were suppported pivotally to the lower casing 25 in the so-called clamshell the casings would be deformed. It is difficult to achieve mutual positioning and a local strain would develop in the support portion resulting in reduced durability. However, by adopting the coupling the upper and lower casings by means of screws, the above-mentioned problem can be avoided. Referring to Fig. 8, it is desirable that the upper casing 24 and the lower casing 25 are coupled in a shiplap style. The above construction is advantageous for the reason that the photoreceptor 42 can be effectively prevented from deteriorating by preventing light from entering into the machine body 2 through the junction between the upper and lower casings. Reference is now made to a sheet inlet tray 22 and a sheet outlet tray 23 of the machine body 2. The tray units 22 and 23 receive, respectively, a sheet to be supplied into the machine body 2 and the sheet ejected out of the machine body 2 after undergoing the image forming process. In the present embodiment, the tray units 22 and 23 are integrated with guide ribs 22g and 23g for guiding the bottom surface of a sheet. This prevents the possible oblique advance of a sheet in conjunction with the lower guide ribs 25a formed on the inner bottom surface of the lower casing 25. Referring to Figs. 2 and 3, the machine body 2 is provided with a sheet inlet 26 for supplying a sheet and a sheet outlet 21 for ejecting a sheet which has undergone an image forming process. The upper casing 24 is provided with notch portions 24a comprising the upper half portions of the sheet inlet 26 and the sheet outlet 21. The lower casing 25 is provided with notch portions 25g comprising the lower half portions of the sheet inlet 26 and the sheet outlet 21. Formed in notch portions 25g of the lower casing 25 are holes 25i as shown in Fig. 7. The holes 25i pivotally support pins 22p (refer to Figs. 2 and 3) of the sheet inlet tray 22 for receiving a sheet to be supplied to the sheet inlet 26 and sheet outlet receive pins 22p (refer to Figs. 2 and 3) support the sheet outlet tray 23 for receiving a sheet ejected through the sheet outlet 21. Because the tray units 22 and 23 are supported pivotally to the machine body 2 in the present embodiment as described above, when it is not used, the tray units 22 and 23 can be put in respective upright positions to be put closer to the upper casing 24 to minimize the occupation space of the duplicating machine. Referring to Figs. 9 through 12, the sheet inlet tray 22 is provided with a sheet side guide 9 for guiding the sides of a sheet being supplied into the machine body 2. The sheet side guide 9 has a pair of cursor units 91a and 91b for determining the lateral sheet position, a pair of rack gears 92a and 92b for moving the cursor units 91a and 91b in opposite directions symmetrically of the tray center line, and a pinion gear 93 engaged with the rack gears 92a and 92b. The cursor units 91a and 91b and the rack gears 92a and 92b are made of resin mold materials. The cursor 91a is so integrated with an end of the rack gear 92a as to project above the end, while the other cursor 91b is integrated with the opposite end of the rack gear 92b. Each of the cursor units 91a and 92b has a recess 91c for guiding the sides of a sheet therein. The rack gear 92a is introduced into a first guide groove 22a formed in an upper surface of the sheet inlet tray 22 for guiding the movement thereof. The other rack gear 92b is introduced into a second guide groove 22b formed in parallel with the first guide groove 22a for guiding the movement thereof. It is noted that both ends of the guide grooves 22a and 22b are closed to prevent the respective gears 92a and 92b from leaving the grooves 22a and 22b. Provided at the positions opposite to the guide grooves 22a and 22b about the center line of the sheet inlet tray 22 are a first rack presser 22c and a second rack presser 22d for preventing the respective rack gears 92a and 92b from leaving the corresponding grooves. The rack pressers 22c and 22d protrude in the sidewise directions of the guide grooves 22a and 22b and slidably press the upper surfaces of the corresponding rack gears 92a or 92b. Each of the rack pressers is selected to have a length permitting insertion of the corresponding one of the rack gears 92a and 92b from above into the respective guide grooves 22a and 22b. The rack gears 92a and 92b are put into the guide grooves 22a and 22b such that the toothed surfaces face each other and engage with the pinion gear 93 at the center of the sheet inlet tray 22. Referring to Fig. 10, the pinion gear 93 is supported by a support pin 22e projecting from the sheet inlet tray 22. The support pin 22e has its upper split end capable of being shrunk in the direction of the diameter and the uppermost end of the support pin 22e is provided with a flange portion 22f for preventing the pinion gear 93 from slipping out of the support pin 22e. With the above construction, merely by putting the pinion gear 93 around the support pin 22e through shrinking the upper end of the support pin 22e, the pinion gear can be supported rotatable. It is noted that a snap ring or the like may be provided at the upper end portion of the support pin 22e instead of adopting the above-mentioned construction. According to the sheet inlet tray 22 of the present embodiment, the sheet side guide 9 can be mounted on the sheet inlet tray 22 merely by putting the rack gears 92a and 92b into the guide grooves 22a and 22b from the side without the rack pressers 22c and 22d, sliding the rack gears 92a and 92b toward the rack pressers 22c and 22d, and putting the pinion gear 93 around the support pin 22e. Furthermore, the cursor units 91a and 91b are integrated with the rack gears 92a and 92b, which leads to reducing the amount of components. Although the sheet inlet tray 22 and the sheet outlet tray 23 are pivotally mounted on the machine body 2 in the above-mentioned example, the tray units may be integrated with the lower casing 25 as shown in Figs. 13 and 14. When the embodiment in Figs. 13 and 14 is selected, the tray units 22 and 23 are not required to be formed independently, which leads to the advantage of reducing the amount of components. Furthermore, there is no need to mount the tray units 22 and 23 to the lower casing 25, which leads to reducing manufacturing cost. In addition, a desirable relative positional precision between the lower guide ribs 25a and the sheet inlet tray 22 can be achieved, which leads to reducing the possible occurrence of sheet transfer error. The above construction is also advantageous because the possible oblique advance of a sheet is prevented by the guide ribs 22g and 23g which are formed on the tray units 22 and 23 for guiding a sheet in conjunction with the lower guide ribs 25a integrated with the bottom of the lower casing 25 as set forth in the present embodiment. Referring to Fig. 15, the aforesaid image forming unit frame 46 is made of a resin mold material integrated with the toner collecting vessel 47 for storing toner collected by the cleaner 45. The image forming unit frame 46 is provided with a photoreceptor mounting section 46a and an image developing unit mounting section 46b. The photoreceptor mounting section 46a supports the cleaner 45 (refer to Figs. 2 and 3) by which toner remaining on the photoreceptor 42 is transferred to the toner collecting vessel 47. In order to scratch the toner remaining on the photoreceptor 42, a cleaning blade 45a is mounted on the image forming frame 46 in the present embodiment. Accordingly, the cleaning blade 45a is directly mounted on the image forming unit frame 46 on which the photoreceptor 42 is mounted, so that an accurate alignment can be achieved No adjustment of the photoreceptor 42 and the cleaning blade 45 is required. Referring to Figs. 16 and 17, an insulated housing 44a of the image transfer charger 44 is integrated with a lower portion of the image forming unit frame 46. At the insulated housing 44a an electric discharge wire 44b is extended perpendicularly to the sheet transfer direction which defines a sheet transfer path between the wire 44b and the photoreceptor 42. Mounted on the insulated housing 44a is an iron plate cover 44c having a bracket-like bent section opening toward the photoreceptor 42 with both ends thereof connected to the insulated housing 44a. The above-mentioned electric discharge wire 44b is covered with the iron plate cover 44c. According to the present embodiment, the insulated housing 44a of the image transfer charger 44 is integrated with the image forming unit frame 46 to which the photoreceptor 42 is mounted, so that the image transfer charger 44 can be mounted in an appropriate position with respect to the photoreceptor 42 merely by mounting the image forming unit frame 46 to the upper casing 24, whereby special alignment between the photoreceptor 42 and the image transfer charger 44 can be eliminated. Furthermore, the amount of components can be reduced as compared with the case that the insulated housing 44a and the image forming unit frame 46 are mounted independently. It is also acceptable to select a construction as shown in Fig. 18 where the image transfer charger 44 is fixed to the lower casing 25. Referring to Fig. 15, the toner collecting vessel 47 has a flat or rectangular tray-like shape and is provided above the lower stream of the sheet transfer means 5 (refer to Fig. 2). Referring to Fig. 2, the toner collecting vessel 47 has an inclined side surface 47c which extends at its one end continuously from a horizontal bottom section 47b and extends at its other end continuously to a ledge section 47a extending toward the sheet outlet 21. The inclined side surface 47c and the ledge section 47a serve cooperatively as a hand guide G. The hand guide G guides insertion of the operator's hand to a position permitting takeout of a small sheet in a business card size passed through the fixing means 6 inside the apparatus body 2. The guide G regulates insertion amount of the operator's hand so that the operator's hand does not exceed a prescribed length due to the side surface 47c. This prevents the operator's hand from coming in contact with the fixing means 6. It is noted that the ledge section 47a is adhered to the upper edge of the sheet outlet 21 when it is introduced in the sheet outlet 21 in order to prevent the sheet from being caught at the upper edge portion. As described above, because a portion of the toner collector 47 serves for the hand guide G, there is no need to provide an independent hand guide, so that the amount of components and production processes and therefore the manufacturing cost can be reduced. Referring to Figs. 19 and 20, another toner collecting vessel 147 has an upward opening. An edge of the upper opening has a stepped portion 147a to which a lid member is adhesively connected by screws b1. The lid member 124e is formed of a member different from the ceiling of the upper casing 24a of the machine body 2. The lid member 124e is formed by bending a plate having a high rigidity such as metal. Provided with the lid member 124e is an upper lid section e1 with which the image forming unit frame 146 covers a blade holding section e2 which extends continuously from the upper lid section e1 toward the photoreceptor (not shown). Fixed to the blade holding section e2 is a cleaning blade 145a which can contact the circumferential surface of the photoreceptor when the photoreceptor is mounted on the toner collecting vessel 147. According to the embodiment shown in Figs. 19 and 20 described as above, assembly is made by mounting the upper lid section e1 on the toner collecting vessel 147 and fixing it to the toner collecting vessel 147 by screws b1 after the cleaning blade 145 is fixed to the blade holding section e2. Setting and mounting of the cleaning blade 145a and the upper lid e1 can be achieved concurrently. Referring to Fig. 21, another toner collecting vessel 247 has a side plate composed of an extension 224a extending from the ceiling surface of an upper casing 224, and a cleaning blade 245a so fixed to a prescribed position of the extension 224a as to come in contact with the circumferential surface of the photoreceptor 42. Referring to Fig. 22, another toner collecting vessel 347 is a resin mold product consisting of a member different from an image forming unit frame 346 mounted below the photoreceptor 42. The toner collecting vessel 347 is provided with a main section 347a opening upward (toward the photoreceptor 42) and a lid section 347b to be mounted on the main section 347a. The lid section 347b has a side wall 347b1 serving for a side wall of the main section 347a and a blade holding section 347b2 extending from the side wall 347bl as bent inward of the main section 347a. Fixed to the blade holding section 347b2 is a cleaning blade 345a which can contact the circumferential surface of the photoreceptor 42 when mounted. Referring to Figs. 2 and 3, the sheet transfer means 5 is to supply a sheet into the machine body 2 and to discharge the sheet through the image forming means. The sheet transfer means 5 comprises functional components such as a pair of sheet feeding rollers 51 for leading a sheet on the sheet inlet tray 22 into the machine body 2, a sheet stopper 52 for halting a sheet transferred from the sheet feeding roller pair 51 in order to put the sheet temporarily in a wait condition, and the fixing means 6. An upper roller 51a of the sheet feeding roller pair 51 is rotatably supported by an upper guide 41b projecting from the image developing unit housing 41a of the image developing unit 41. In other words, the upper guide 41b serves for a support member of the upper roller 51a. Furthermore, the sheet stopper 52 is so supported by a pivot 52a. The sheet stopper 52a is so urged by a coil spring (not shown) in clockwise direction in Figs. 2 and 3 to project into the sheet transfer path. When advancing to the sheet transfer path, the sheet stopper 52 checks the leading end of a sheet to put the sheet into a wait condition. When the document table 1 is driven to a prescribed position, the sheet stopper 52 is turned in counterclockwise direction by a mechanism interlocked with the document table 1, thereby the sheet stopper retreats in order to supply the halted sheet to the image forming means 4. The fixing means 6 for fixing the toner image transferred onto a duplication sheet comprises functional components including a heat roller 61 heated by a built-in heater and a presser roller 62 driven with the operation of the heat roller 61. The presser roller 62 is mounted swingably in the vertical and horizontal directions being urged upward by a spring (not shown). By guiding a shaft 62a of the presser roller 62 into a groove 63a provided in a stay 63 supporting the heat roller 61, the relative position of the presser roller 62 with respect to the heat roller 61 is determined. In the present embodiment, the presser roller 62 of the fixing means 6 is supported at a support member 25d composing a part of the lower casing 25. By supporting the presser roller 62 at the support member 25d, the presser roller 62 moves with the support member 25d when opening the machine body 2 by making the support member 25d pivot, thereby a portion of the sheet transfer path corresponding to the fixing means 6 can be opened with respect to the bottom of the machine body. With the above construction, a sheet jam removing operation and a maintenance operation can be carried out more easily in the present embodiment in comparison with the conventional machine. According to the above-mentioned construction of the present embodiment, the exposing means 3, the image forming means 4, the drive roller 61 of the fixing means 6, and the drive roller 51a of the sheet transfer means 5 are mounted in the upper casing 24a, while the driven roller 62 of the fixing means 6 and the driven roller 51b of the sheet transfer means 5 are mounted in the lower casing 24b. Referring to Fig. 6, the drive means 7, for driving the photoreceptor 42, a toner supply roller 41d, a toner stirring roller 41e, and an image developing roller 41f of the image developing unit 41, the upper roller 51a of the sheet transfer means 5, the heat roller 61 of the fixing means 6, and other members, comprises functional components which include a power source, i.e. a motor 71, and a gear mechanism 72 for transmitting the power and other members. The functional components of the drive means 7 are mounted on a mounting section 24h formed inside of the upper casing 24 together with electrical equipments 8 such as a circuit board for controlling the drive operations of the drive means 7. Concentrating the drive means 7 and the electrical equipments 8 in the upper casing 24 enables an easy and efficient wiring of the drive means 7 and wiring between the electrical equipments. In more detail, when the drive means 7 and the electrical equipments 8 are mounted respectively in the upper casing 24 and the lower casing 25, it is necessary to perform wiring between the upper casing 24 and the lower casing 25. This requires troublesome wiring works. On the contrary, by concentrating the above-mentioned means and equipments in the upper casing 24, the wiring can also be concentrated. The wiring can be gathered in a half section of the apparatus body and provides an easy and efficient wiring works. The following describes another embodiment provided with a ventilating fan for cooling the interior of the machine body 2 with reference to Fig. 23. In the body 2 of an image forming apparatus in Fig. 23, there are provided a fresh air inlet 2a (shown only in Fig. 24) for taking fresh air into the machine body 2, and an air outlet 2b for discharging air which has absorbed heat generated in the machine body 2. In the present embodiment, an upper portion of the sheet outlet 27 is made to concurrently serve as the air outlet 2b. Mounted in the machine body 2 is a toner collecting vessel 47 integrated with the image forming unit frame 46 of the image forming means 4 which is disposed between the upper and lower casings 24 and 25. The toner collecting vessel 47 has a tray-like shape having a rectangular top configuration, and the upper opening thereof is closed by a lid 24c formed on the upper casing 24 in the same manner as shown in Figs. 2 and 3. Beside the toner collecting vessel 47 is provided a ventilating fan 17 for discharging heated air at a position above the lower stream end of the sheet transfer means 5. The ventilating fan 17 consists of, for example, a sirocco fan, and air inlet sections provided at both ends of the fan communicate with either end of the fluorescent lamp 31 via a pair of air inlet ducts D provided at both sides of the toner collecting vessel 47 (refer to Figs. 24 and 25). Referring to Figs. 24 and 25, the air inlet ducts D comprise abutting duct members 28 and 29 in the form of a pair of first and second downward ribs 28a and 28b formed apart at a certain interval from the ceiling surface of the upper casing 24 and a pair of first and second upward ribs 29a and 29b formed apart at the same interval on the bottom surface of the lower casing 25. The fixing means 6 has an end portion extending into the air inlet ducts D, so that the heat generated from the heat roller 61 of the fixing means 6 can be efficiently discharged through the air inlet ducts D. The exposing means 3 is provided with an optical housing 33, for mounting the fluorescent lamp 31, to which the upper casing 24 is fixed by screw means, so that the entire body of the exposing means 3 can be held by the machine body 2. Although not shown in the drawings, the optical housing 33 is provided with a first notch portion facing the fresh air inlet 2a formed in the machine body 2 and a second notch portion facing the air inlet ducts D. Therefore, when the ventilating fan 17 produces an air stream in the direction indicated by an arrow A in Fig. 24, outside air is introduced through the fresh air inlet 2a into the machine body 2. Incoming fresh air absorbs the heat inside the machine body 2 by passing through the optical housing 33 as well as absorbs the heat generated from the fixing means 6 by passing through the air inlet ducts D. It is discharged through the air outlet 2b to the outside of the machine body 2. It is noted that the air inlet ducts D permit a variety of modifications thereof aside from the above-mentioned embodiment. The air inlet ducts D may be disposed only in the optical unit housing 33 or in a part of the optical unit housing 33 and a part of the upper casing 24 as shown in Figs. 26 through 30. In more detail with reference to Figs. 26 and 27, the air inlet ducts D include duct members 33a each of which has a groove-like shape integrated with the optical unit housing 33 and the ceiling surface of the upper casing 24. The air inlet ducts D may comprise duct members 33a each of which has an L section shape and downward ribs 24f formed on the ceiling surface of the upper casing 24 as shown in Fig. 28. The air inlet ducts D may comprise duct members 33a having a flat-plate shape, the downward ribs 24f, and second downward ribs 24g formed in parallel with the downward ribs 24f on the ceiling surface of the upper casing 24 as shown in Fig. 29. Each of the duct members 33a may have a frame-like section shape as shown in Fig. 30. In the above case, the air inlet ducts D can consist only of the duct members 33a without any combination with the ceiling surface of the upper casing 24 as shown in Fig. 30. The air inlet ducts D may comprise either the toner collecting vessel 47 alone or a combination of a part of the toner collecting vessel 47 and a part of the machine body 2 as shown in Figs. 31 through 34. Describing the above-mentioned embodiment in more detail with reference to Figs. 31 and 32, the air inlet ducts D is composed of duct members 47a each of which has a groove-like shape and concurrently serves as a part of a side wall of the toner collecting vessel 47 provided along either side of the toner collecting vessel 47, second downward ribs 24g which extend downward from the ceiling surface of the upper casing 24 in parallel with first downward ribs 24f and abut the lower end portions thereof to the duct members 47a, the first downward ribs 24f, and the ceiling surface of the upper casing 24. When the air inlet ducts D include either of the toner collecting vessel 47 alone or a combination of a part of the toner collecting vessel 47 and a part of the machine body 2, the air inlet ducts D may be formed by abutting the upper end portions of the duct members 47a directly to the ceiling surface of the upper casing 24 without providing the downward ribs 24f and 24g on the ceiling surface of the upper casing 24 as shown in Fig. 33. Each of the duct members 47a may be formed to have a frame-like section shape as shown in Fig. 34. In the above case, the air inlet ducts D can consist only of the duct members 47a without any combination with a part of the upper casing 24. The air inlet ducts D may comprise either a lid 48 provided on the toner collecting vessel 47 alone or a combination of a part of the lid 48 and a part of the upper casing 24 as shown in Figs. 35 through 38. Describing the above-mentioned embodiment in more detail with reference to Figs. 35 and 36, the air inlet ducts D are, integrally along with both sides of the lid 48 of the toner collecting vessel 47, composed of duct members 48a each of which has an L section shape and serves for a part of the side wall of the lid 48, downward ribs 24f which extend downward from the ceiling surface of the upper casing 24 and abut the lower end portions thereof to the duct members 48a, and the ceiling surface of the upper casing 24. The lid 48 is a synthetic resin mold product with which the upper opening of the toner collecting vessel 47 is covered to prevent toner from scattering into the toner collecting vessel 47. With a combination of the lid 48 provided on the upper portion of the toner collecting vessel 47 and a part of the upper casing 24, the following constructions of the air inlet ducts D are permitted. The air inlet ducts D may be formed by abutting the upper end portions of duct members 48a, each of which has a groove-like section shape, directly to the ceiling of the upper casing 24 which eliminates the downward ribs 24f as shown in Fig. 37. Each of the duct members 48a may have a frame-like section shape as shown in Fig. 38. In the above case, the air inlet ducts D can comprise only the duct members 48a without any combination with a part of the upper casing 24. According to each of the above-mentioned embodiments, by providing a pair of air inlet ducts D, particularly the air having an elevated temperature around both ends of the fluorescent lamp 31 can be efficiently discharged. This is possible with an inexpensive ventilating fan 17 having a small ventilating capacity without reducing the air discharging efficiency. Furthermore, because the air inlet ducts D are composed of a part of the upper casing 24 and a part of the lower portion of the machine body 2, the amount of components and the amount of assembling process are not increased and the provision of the air inlet ducts D incurs no significant cost increase.

Claims: An image forming apparatus comprising functional components within a resin apparatus body (2) including: exposing means (3) for forming a latent electrostatic image on a photosensitive means (42); image forming means (4) for developing said latent electrostatic image formed on said photosensitive means (42) into a toner image and transferring said toner image onto a sheet; sheet transfer means (5) for transferring the sheet into said resin apparatus body (2) and conveying said sheet through said image forming means (4); fixing means (6) for fixing said toner image transferred on said sheet; drive means (7) for driving said sheet transfer and fixing means (5, 6); and electrical equipments (8): characterized in that said resin apparatus body (2) comprises mutually separable monocoque structured upper and lower casings (24, 25) connected to one another by screw means. An image forming apparatus as claimed in Claim 1, wherein said image forming means (4) is arranged in said upper casing (24) having four side walls and a ceiling panel serving as an exterior cover, said upper casing (24) having integrally formed ribs (24d, 24f) projecting toward components (41) of said image forming means (4), and a part of said sheet transfer means (5) is arranged in said lower casing (25) having four side walls and a bottom serving as an exterior cover, said lower casing (25) having guide ribs (25a) integrally formed with said bottom thereof. An image forming apparatus as claimed in Claim 2, wherein said apparatus body (2) is formed by engaging said upper casing (24) with said lower casing (25) in a shiplap construction. An image forming apparatus as claimed in Claim 2, wherein said guide ribs (25a) of said lower casing (25) provide a lower guide for guiding the bottom surface of a sheet. An image forming apparatus as claimed in Claim 2, 3 or 4, further comprising a support member (25d) disposed at the bottom of said lower casing (25) for supporting part of components (25e) of said sheet transfer means (5), said support member (25d) arranged below a sheet transfer path and drawable from said apparatus body (2), wherein components (62) which form said fixing means (6) are arranged below said sheet transfer path. An image forming apparatus as claimed in Claim 5, wherein said support member (25d) is rotatably supported by a supporting pivot (25c) disposed downstream in said sheet transfer path, said support member (25d) supports said components (62) of said fixing means (6) near said supporting point (25c) and said support member (25d) is introduced in an opening (25b) provided in said lower casing (25). An image forming apparatus as claimed in any one of the Claims 1 to 6, wherein said lower casing (25) comprises a sheet inlet tray (22) for receiving a sheet to be supplied into said apparatus body (2) and a sheet outlet tray (23) for receiving the sheet which has undergone an image forming process and is discharged from said apparatus body (2). An image forming apparatus as claimed in Claim 1, wherein said exposing means (3), said image forming means (4), a drive roller (61) of said fixing means (6), and a drive roller (51a) of said sheet transfer means (5) are arranged in said upper casing (24), and a driven roller (62) of said fixing means (6), as well as a driven roller (51b) of said sheet transfer means (5) are arranged in said lower casing (25). An image forming apparatus as claimed in Claim 8, wherein said drive means (7) and electrical equipments (8) are arranged in said upper casing (24) of said apparatus body (2). An image forming apparatus as claimed in Claim 1, wherein said sheet transfer means (5) comprises a sheet inlet tray (22) for receiving a sheet supplied into said apparatus body (2) and a sheet outlet tray (23) for receiving a sheet having undergone an image forming process and been discharged from said apparatus body (2). An image forming apparatus as claimed in Claim 10, wherein said sheet inlet tray (22) and said sheet outlet tray (23) are integrated with said lower casing (25). An image forming apparatus as claimed in Claim 10, wherein said sheet inlet tray (22) and said sheet outlet tray (23) are pivotally supported on said lower casing (25) as capable of rising. An image forming apparatus as claimed in Claim 10, wherein said sheet inlet tray (22) is integrally provided with a guide rib section (22g) so aligned with the guide ribs (25a) integrally formed in said lower casing (25) as to guide the bottom surface of a sheet. An image forming apparatus as claimed in Claim 10, wherein said sheet outlet tray (23) is integrally formed with a guide rib section (23g) so aligned with the guide ribs (25a) integrally formed in said lower casing (25) as to guide the bottom surface of a sheet. An image forming apparatus as claimed in Claim 10, wherein said sheet inlet tray (22) comprises a sheet side guide (9) for guiding a sheet into said apparatus body (2). An image forming apparatus as claimed in Claim 15, wherein said sheet side guide (9) comprises a pair of cursor units (91a, 91b) movable laterally to the direction of sheet insertion in said sheet inlet tray (22). An image forming apparatus as claimed in Claim 16, wherein said pair of cursor units (91a, 91b) are integrally formed with corresponding ends of a pair of rack gears (92a, 92b) respectively, said rack gears (92a, 92b) being interlinked by way of a pinion gear (93). An image forming apparatus as claimed in Claim 17, wherein said rack gears (92a, 92b) are inserted in respective guide grooves (22a, 22b) provided in said sheet inlet tray (22) and each one of said guide grooves (22a, 22b) is provided with a rack hold-down member (22c, 22d) for preventing said rack gears from leaving said grooves (22a, 22b). An image forming apparatus as claimed in Claim 17, wherein said pinion gear (93) is supported by a support pin (22e) which has an upper portion (22f) for preventing said pinion gear (93) from slipping out. An image forming apparatus as claimed in Claim 19, wherein said upper portion is a flange (22f) which is shrinkable in the direction of the diameter of said support pin (22e). An image forming apparatus as claimed in any one of the Claims 1 to 20, wherein said upper casing (24) comprises an opening (24b) through which a toner cartridge (41c) is received and guide plates (24d) for guiding said toner cartridge (41c) when said toner cartridge is inserted or removed through said opening (24b) and a cover (24g) for closing said opening. An image forming apparatus as claimed in any one of the Claims 1 to 21, wherein said image forming means (4) comprises an image forming unit frame (46) disposed in said apparatus body (2) and a toner collecting vessel (47) for collecting toner remaining on a surface of said photosensitive means (42). An image forming apparatus as claimed in Claim 22, wherein said image forming unit frame (46) is integrally formed with an insulated housing (44a) of an image transfer charger (44). An image forming apparatus as claimed in Claim 22, wherein said toner collecting vessel (47) is integrally formed with said image forming unit frame (46). An image forming apparatus as claimed in Claim 22, wherein said toner collecting vessel (147) is covered with a lid (124e). An image forming apparatus as claimed in Claim 25, wherein said lid (124e) of said toner collecting vessel (147) is formed by part of said upper casing (24). An image forming apparatus as claimed in Claim 26, wherein said lid (24e) of said toner collecting vessel (247) is formed by a part of the ceiling panel (224) of said upper casing (24) and a downward rib section (224a) which extends downwardly from said ceiling panel to seal the edge of an opening of said toner collecting vessel (247). An image forming apparatus as claimed in Claim 27, wherein said edge of said opening of said toner collecting vessel (47) is fixed to said downward rib section (24f) by screw means. An image forming apparatus as claimed in Claim 22, wherein said toner collecting vessel (247) is provided with a cleaning blade (245a) for scraping toner off a surface of said photosensitive means (42). An image forming apparatus as claimed in Claim 29, wherein said toner collecting vessel (147) has upper covered portion (124e) to which said cleaning blade (145a) for scraping toner off said surface of said photosensitive means (42) is fixed. An image forming apparatus as claimed in Claim 29, wherein said toner collecting vessel (247) is formed by a part of said upper casing (24) to which said cleaning blade (245a) for scraping toner off said surface of said photosensitive means (42) is fixed. An image forming apparatus as claimed in Claim 22, wherein said toner collecting vessel (47) is provided with a hand guide (G) for permitting removal of a small size sheet having passed through said fixing means (6) and serves as a manual access guide (G) for preventing the human hand from contact with said fixing means (6) inside of said apparatus body (2). An image forming apparatus as claimed in Claim 32, wherein a part of said manual access guide (G) of said toner collecting vessel (47) is formed by a ledge (47a) disposed in close contact with an upper edge of said sheet outlet (23). An image forming apparatus as claimed in any one of the Claims 1 to 33, wherein said exposing means (3) is provided with a rod-shaped lamp (31) for illuminating a document arranged horizontally in said apparatus body (2), wherein a ventilating fan (17) is provided for discharging heat developed in said apparatus body (2) and a pair of air inlet ducts (28, 29) for communicating said ventilating fan (17) with both ends of said lamp (31). An image forming apparatus as claimed in Claim 34, wherein said pair of air inlet ducts (28, 29) is formed by a pair of ribs (28a, 28b) extending downwardly from the ceiling of said upper casing (24) and ribs (29a, 29b) extending upwardly from the inner bottom surface of said lower casing (25), the ribs abutting each other in alignment. An image forming apparatus as claimed in Claim 34, wherein said pair of air inlet ducts (28, 29) is formed by a duct member (33a) formed at least on an optical housing (33) in which said lamp (31) is mounted. An image forming apparatus as claimed in Claim 36, wherein said duct member (33a) is formed by a combination of said optical housing (33) and said upper casing (24). An image forming apparatus as claimed in Claim 34, wherein said air inlet duct is provided at a prescribed position between said ventilating fan (17) and said lamp (31) and is formed by a duct member (D) disposed at least on said toner collecting vessel (47). An image forming apparatus as claimed in Claim 38, wherein said duct member is formed by a combination of said toner collecting vessel (47) and said upper casing (24). An image forming apparatus as claimed in Claim 34, wherein said air inlet duct is provided at a prescribed position between said ventilating fan (17), said lamp (31) and at least said lid of said toner collecting vessel (47). An image forming apparatus as claimed in Claim 40, wherein said duct member (D) is formed by a combination of said lid of said toner collecting vessel (47) and said upper casing (24).

Inventors: AIKAWA YUKIHIRO, AKASHI MASAKATSU, HIROBE JUNICHI, ISHII SATOSHI, KOBAYASHI MASAHIKO, KUSUDA TOSHIAKI, MAKIE IKUO, OHATA YOSUKE, SUGAYA TSUTOMU, TANAKA YOSHIHISA, AIKAWA, YUKIHIRO, AKASHI, MASAKATSU, HIROBE, JUNICHI, ISHII, SATOSHI, KOBAYASHI, MASAHIKO, KUSUDA, TOSHIAKI, MAKIE, IKUO, OHATA, YOSUKE, SUGAYA, TSUTOMU, TANAKA, YOSHIHISA
Applicants: MITA INDUSTRIAL CO LTD, MITA INDUSTRIAL CO., LTD.
Application year: 1992
Main classification: G03G15
IPC codes: G03G15, G03G21