Image-forming machine

Abstract: An image-forming machine comprising a process unit (6) mounted detachably at a predetermined position, said process unit (6) including an electrostatographic material, a cleaning device (18) having a cleaning blade (30), and a cover member (14) to be selectively held at a covering position at which it covers part of the electrostatographic material, and said cleaning blade (30) in the cleaning device (18) being mounted so as to be free to move between an operative position at which it makes contact with the electrostatographic material and a non-operative position which is away from the electrostatographic material, said cleaning blade being elastically biased toward the operative position by a spring means (180); wherein a forcing means (182) is provided, which when the cover member (14) is in the covering position, holds the cleaning blade (30) in the non-operative position against the elastic biasing action of said spring means (180).

Description: This invention relates to an image-forming machine, such as printer or a copying machine, of the electrostatic type which forms a latent electrostatic image on an electrostatographic material, developing it to a toner image, and thereafter, transferring the toner image to a receptor material. Image-forming machines such as printers or copying machines of the above-described electrostatic type have been widely used. Such an image-forming machine usually comprises an electrostatographic material disposed on the surface of a rotating drum or an endless belt, a latent electrostatic image-forming means for forming a latent electrostatic image on the electrostatographic material, a developing device for developing the latent electrostatic image to a toner image, a transfer means for transferring the toner image on the electrostatographic material to a receptor material which may usually be a sheet of paper, and a cleaning device for removing the residual toner from the electrostatographic material after the toner image is transferred therefrom. The latent electrostatic image-forming means includes a charging corona discharger for uniformly charging the electrostatographic material and an optical system for selectively exposing the electrostatographic material corresponding to an image to be formed. A typical example of the developing device includes a development housing holding a developer, a developer applicator means for applying the developer in the development housing to the electrostatographic material, and an agitating means for agitating the developer within the development housing. A typical example of the cleaning device comprises a toner removing means for removing the residual toner from the electrostatographic material, and a toner recovery housing extending in the width direction along the electrostatographic material for receiving the toner removed from the electrostatographic material by the toner removing means. The toner removing means is conveniently comprised of a cleaning blade which is adapted to make contact with the electrostatographic material by being elastically biased. The cleaning means, in many cases, further includes a toner collecting chamber that can be formed within a rotating drum on the surface of which the electrostatographic material is disposed, or within the developing device. In a relatively small-sized image forming machine, it is convenient to construct a replaceable process unit by combining the electrostatographic material with the developing device and/or the cleaning device, and mount it detachably on a desired site. In this case, a cover member adapted to be selectively held at a covering position at which it covers part of the electrostatographic material is also provided. The cover member may be detachably mounted on the process unit in a mode in which it is held at the covering position; or in a mode in which it is free to move between the covering position and a non-covering position at which it exposes part of the electrostatographic material to view. In some cases, the charging corona discharger in the latent electrostatic image-forming means is also included in the process unit. The conventional image-forming machines described above, however, have problems to be solved. When at least the cleaning device is combined with the electrostatographic material to constitute a detachable process unit, it is necessary to bias the cleaning blade in the cleaning device elastically and bring it into contact with the electrostatographic material when the process unit is mounted on a required site and actually used. When the process unit is not mounted on the required site, it is desired to separate the cleaning blade from the electrostatographic material and avoid deterioration or damage in the electrostatographic material and/or the cleaning blade. The prior art, however, has failed to satisfy the above requirement without giving rise to another problem such as a great increase in the cost of production. Document EP-A- 0 262 640 describes an image-forming machine having the features of the preamble of claim 1. Summary of the Invention An object of the invention is to separate the cleaning blade in the cleaning device from the electrostatographic material when the process unit is not mounted on a required position but keep it in contact with the electrostatographic material when the process unit is mounted on the required site and actually used, without giving rise to another problem such as a great increase in the cost of production. A novel feature of the invention is that in a process unit comprising the electrostatographic material and at least the cleaning device, the cleaning blade of the cleaning device is mounted so as to be free to move between an operating position at which it makes contact with the electrostatographic material and a non-operating position at which it departs from the electrostatographic material and the cleaning blade is elastically biased to the operating position by spring means, and moreover, a forcing means is disposed which forces the cleaning blade into the non-operating position against the elastic biasing action of the spring means when the cover member of the process unit is brought to the covering position at which it covers part of the electrostatographic material. Figure 1 is a simplified view showing a laser beam printer as one specific embodiment of the imageforming machine constructed in accordance with this invention; Figure 2 is an exploded view showing a process unit for use in the laser beam printer of Figure 1; Figure 3 is a sectional view showing a process unit for use in the laser beam printer of Figure 1; Figure 4 is a partial perspective view showing the cleaning blade and its related parts used in the cleaning devices in the process units depicted in Figures 2 and 3; Figure 5 is a partial sectional view showing the cleaning blade of Figure 4 and its related parts. With reference to the accompanying drawings, preferred embodiments of the image-forming machines of this invention improved in various respects will be described below in detail. Figure 1 shows a laser beam printer shown generally at 2. The printer is comprised of a printer body 4 shown by a two-dot chain line in a simplified manner and a process unit 6 to be mounted detachably on the printer body 4. The structure of the printer 2 excepting the structure of the process unit 6 and the method of mounting and detaching the process unit 6 on and from the printer body 4 may be substantially the same as in the laser beam printer described and shown in detail in the specifications and drawings of Japanese Patent Applications Nos. 290740/1987 (filed on November 19, 1987 and entitled "Image-Forming Machine") and 301775/1987 (filed on November 30, 1987 and entitled "ImageForming Machine"). Accordingly, these applications are cited herein by way of reference, and a detailed description of the structure of the printer 2 and the method of mounting and detaching the process unit 6 is omitted herein. With reference to Figure 2, the process unit in the illustrated embodiment is constructed by assembling four components each formed and assembled independently, namely a first component 8, a second component 10, a third component 12 and a fourth component 14. With reference to Figures 2 and 3, the first component 8 has a rotating drum 16 and a cleaning device 18. The second component 10 is a developing device. The third component constitutes an upper fixed cover member covering a greater portion of the upper surfaces and both side surfaces of the first and second components 8 and 10 and at the same time, includes a charging corona discharger 22. The fourth component 14 is a cover member for covering the lower portion of the rotating drum 16 and detachably mounted on the covering position shown in Figure 3. Further, with reference to Figures 2 and 3, the first component 8 has a pair of supporting side walls 24 and 26 dispersed with a predetermined distance therebetween, and the rotating drum 16 is rotatably mounted between these supporting walls 24 and 26. An electrostatographic material which may be formed of a suitable material such as an organic photosemiconductor is disposed on the peripheral surface of the rotating drum 16. The rotating drum 16 has an input shaft (not shown) projecting through the supporting side wall 26. When the process unit 6 is mounted in position on the printer body 4 (Figure 1), the input shaft is drivingly coupled to a driving source (not shown) which may be an electric motor via a suitable drive coupling means (not shown), and at the time of performing the image-forming process, the rotating drum 16 is rotated in the direction shown by an arrow 28. The cleaning device 18 includes a cleaning blade 30 adapted to make contact with the peripheral surface of the rotating drum 16 by being biased elastically. The cleaning blade 30 constitutes a toner removing means for removing the residual toner from the peripheral surface of the rotating drum 16 after a toner image formed on the peripheral surface is transferred to a receptor material. The method of mounting the cleaning blade 30 and its related structure will be described in detail later on. The cleaning device 18 includes a toner recovery housing 32 disposed below the cleaning blade 30. The toner recovery housing 32 extends between the supporting side walls 24 and 26 alongside the rotating drum 16, and receives the toner which is scraped off downwardly from the rotating drum 16 by the cleaning blade 30. When the components 8, 10, 12 and 14 constituting the process unit 6 are combined properly, an opening protruding end portion 66 of the sealing member 64 is projected outwardly through a slit 68 formed in the front side wall 106 of the third component 12, and bonded to the surface of the front side wall 106 by means of a bonding piece 70, as indicated by a two-dot chain line in Figure 2. Until the process unit 6 is actually put to use, the sealing member 64 is kept unopened, and therefore the developer 60 is held only in the developer cartridge member 48 and therefore no developer 60 exists in the developer housing member 46. When the process unit is to be mounted in position on the printer body 4 (Figure 1), the sealing member 64 is removed from the inclined lower surface of the developer cartridge member 48 by pulling the protruding end portion 66 (Figure 2), and the inclined lower surface is opened. As a result, the developer 60 is permitted to flow from the cartridge member 48 into the main development housing member 46. With reference to Figures 4 and 5 as well as Figure 3, in the process unit 6 improved in accordance with this invention, the cleaning blade 30 in the cleaning device 18 is mounted so as to be free to move between a non-operative position shown in Figure 3 and an operative position shown in Figure 5. Mainly with reference to Figure 4, the cleaning blade 30, which may be an elongate plate-like member formed of a suitable elastomeric material such as synthetic rubber, is fixed at its base portion (i.e., the left end portion in Figures 3 and 5) to the under surface of a blade support 162 by bonding or otherwise. The blade support 162 which may be formed of a suitable metallic plate has a flat plate-like main portion extending slenderly in the width direction, and an upright wall 164, extending to both sides in the width direction, is formed at the front edge (the right edge in Figures 3 and 5) of the flat plate-like main portion. At the rear edge of the flat plate-like main portion is formed a rectangular projecting piece 166 projecting rearwardly from nearly the central part of the rear edge in its width direction. A rectangular opening 168 is formed in the projecting piece 166. As will be clear from the description hereinafter, the opening 168 constitutes an engaged means in a forcing means for forcing the cleaning blade 30 to the non-operative position. On the other hand, an upstanding subsidiary supporting side wall 169 is disposed inwardly of each of the supporting side walls 24 and 26 in the first component element 8. Guiding protrusions 170 and 172 extending parallel to each other with a predetermined distance therebetween in their inside surface of the subsidiary supporting side wall 169, and a guiding groove 174 is defined between the guiding protrusions 170 and 172. As can be seen from Figures 3 and 5, the guiding groove 174 extends roughly in the normal direction of the rotating drum. The blade support 162 can be mounted by inserting its both side portions in the width direction slidably in the guiding groove 174. Thus, the cleaning blade 30 is mounted so as to be free to move roughly in the normal direction of the rotating drum 16 between the operative position and the non-operative position. An opening 178 is formed in a nearly central part in the width direction in a rear wall 176 extending between the rear edges of the supporting inside walls 24 and 26, and the projecting piece 166 formed at the rear edge of the blade support 162 projects outwardly through the opening 178. Between the rear wall 176 and the upstanding wall 164 of the blade support 162 are disposed two compression coil springs 180 spaced from each other in the width direction. The springs 180 elastically bias the blade 162 toward the rotating drum 16, and thus bias the cleaning blade elastically to an operative position at which the free end edge of the cleaning blade 30 makes contact with the surface of the rotating drum 16, namely to the operative position shown in Figure 5. A short rod (not shown) for fitting over the end portion of the spring 180 may be provided in the inside surface of the rear wall 176 and the rear surface of the upright wall 164. With reference to Figures 2 and 3, at the rear end edge (left end edge in Figure 3) of the cover member 14 detachably mounted on the process unit 6 is formed a protrusion 182 extending upwardly from nearly the central part of the rear end edge in the width direction. This protrusion 182 constitutes an engaging means in the forcing means for holding the cleaning blade 30 in the non-operative position. As is clearly shown in Figure 3, the protrusion is preferably of a wedge shape whose thickness progressively decreases upwardly. A forwardly projecting lock protrusion 184 is attached to the upper end of the protrusion 182. A rearwardly extending press-down piece 186 is attached to the base end portion of the protrusion 182. In mounting the cover member 14 on the process unit 6, a front end edge portion 188 of the cover member 14 is inserted into a receiving groove 190 (Figure 3) formed in the lower end of the second component element which is the developing device 10. Then, the rear edge portion of the cover member 14 is elevated to the position shown in Figure 3, and the lock protrusion 184 formed in the upper end of the protrusion 182 is elastically engaged with the engaging protrusion 187 (Figures 3 and 5) formed on the outside surface of the rear wall 176. As a result, the cover member 14 is detachably mounted at the covering position shown in Figure 3. As can be seen by comparing Figure 5 with Figure 3, while the rear edge portion of the cover member 14 is elevated to the position shown in Figure 3, the protrusion 182 formed in the cover member 14 gets into the opening 168 formed in the protruding piece 166 of the blade supporting member 162, and moves the blade support 162 and the cleaning blade 30 fixed thereto to the left in Figures 3 and 5 against the elastic biasing action of the springs 180. When the cover member 14 is mounted on the process unit 6, the cleaning blade 30 is forced and held at the non-operative position shown in Figure 3. At the non-operative position, the cleaning blade 30 is moved away from the peripheral surface of the rotating drum 16. Accordingly, when the cover member 14 is mounted on the process unit 6 and the process unit 6 is not in use, the cleaning blade 30 is away from the peripheral surface of the rotating drum, and degradation and damage of the electrostatographic material and/or the cleaning blade are effectively prevented. In mounting the process unit 6 on the printer body 4 (Figure 1), the cover member 14 is removed from the process unit 6 prior to the mounting of the process unit. At this time, the press-down piece 186 is pressed downwardly to displace the lock protrusion 184 elastically, and thus to remove it from the engaging protrusion 187 (Figures 3 and 5). Then, the rear edge portion of the cover member 14 is lowered and the protrusion 182 is detached from the opening 168 formed in the protruding piece 166 of the blade support 162. Thereafter, the front edge portion 188 of the cover member 14 is detached from the receiving groove 190 (Figure 3) formed at the lower end of the developing device 10. When the protrusion 182 of the cover member 14 is detached from the opening 168 formed in the protruding piece 166 of the blade support 162, the cleaning blade 30 is moved to the operative position shown in Figure 5 by the elastic biasing action of the springs 180, and the free end edge of the cleaning blade 30 is brought into contact with the peripheral surface of the rotating drum 16. If desired, instead of detachably mounting the cover member 14 at the predetermined covering position of the process unit, it is possible to mount the cover member 14 so as to be free to move between the predetermined covering position and a non-covering position at which a predetermined portion of the peripheral surface of the rotating drum 16 is exposed to view, force the cleaning blade 30 to the non-operative position when the cover member 14 is held at the covering position, and elastically bias the cleaning blade 30 to the operative position when the cover member 14 is held at the non-covering position.

Claims: An image-forming machine comprising a process unit (6) mounted detachably at a predetermined position, said process unit (6) including an electrostatographic material, a cleaning device (18) having a cleaning blade (30), and a cover member (14) to be selectively held at a covering position at which it covers part of the electrostatographic material, and said cleaning blade (30) in the cleaning device (18) being mounted so as to be free to move between an operative position at which it makes contact with the electrostatographic material and a non-operative position which is away from the electrostatographic material, said cleaning blade being elastically biased toward the operative position by a spring means (180); characterised in that a forcing means (182) is provided, which when the cover member (14) is in the covering position, holds the cleaning blade (30) in the non-operative position against the elastic biasing action of said spring means (180). The image-forming machine of claim 1 in which the cover member (14) is detachably mounted on the covering position, and when the cover member (14) is mounted in the covering position, the forcing means (182) holds the cleaning blade (30) in the non-operative position, and when the cover member (14) is removed from the covering position, the spring means (180) biases the cleaning blade (30) elastically into the operative position. The image-forming machine of claim 1 in which the forcing means (182) is comprised of an engaging means annexed to the cover member (14) and an engaged means (166) annexed to the cleaning blade (30), and when the cover member (14) is held at the covering position, the engaging means acts (182) on the engaged means (166) to hold the cleaning blade (30) in the non-operative position. The image-forming machine of claim 3 in which the engaging means is constructed of a wedge-shaped protrusion (182), and the engaged means (166) is formed of an opening (168) which receives the wedge-shaped protrusion (182). The image-forming machine of claim 1 in which the electrostatographic material is disposed on the peripheral surface of a rotating drum (16), and the cleaning blade (30) is mounted so that it is free to move between the operative position and the non-operative position roughly in the normal direction of the rotating drum (16).

Inventors: KOYAMA SHIGEO, MAEDE HIROYUKI, MAESHIMA MASANOBU, OTSUKA MASAO, SATO TOSHIHIRO, TSUCHIYA HIROAKI, TSUTSUI EIJI, KOYAMA, SHIGEO, MAEDE, HIROYUKI, MAESHIMA, MASANOBU, OTSUKA, MASAO, SATO, TOSHIHIRO, TSUCHIYA, HIROAKI, TSUTSUI, EIJI
Applicants: MITA INDUSTRIAL CO LTD, MITA INDUSTRIAL CO. LTD.
Application year: 1989
Main classification: G03G21
IPC codes: G03G21, G03G15