Method and Apparatus for Loading/Unloading a Drum Member

This invention relates to a method and an apparatus for loading/unloading a drum member relative to a frame in which the drum member is used.

In an electro-photographic printing apparatus or an electro-photographic copier, an electro-static latent image forming drum coated with photosensitive material is provided. In such apparatus, many associated devices such as a corona charger, a developer, pre-cleaning decharger, etc. are arranged close to the drum. Therefore, when the drum is to be loaded into or unloaded from the frame for inspections or replacement, very careful handling is required, or else the drum will be damaged by hitting these devices.

Damage to the drum is also likely in a magnetic drum memory apparatus or any other apparatus including a sensitive drum member provided with associated devices in its vicinity.

The drum member is usually supported by a center shaft, which is secured at one end to the frame of the apparatus. The other end of the center shaft is free or easily detachably fixed to the frame.

A conventional method of loading/unloading the drum includes the steps of connecting a separate tool such as an extension rod to the free end of the center shaft for elongating or extending the center shaft, and drawing out the drum while guiding the drum along the extension rod.

Another prior art method, as shown in Japanese laid-opened patent application Tokkaisho No. 60-15942, includes the steps of providing a center shaft made as a pipe, providing a special rod having a length longer than the length of the drum, inserting the rod into the center shaft pipe, securing one end of the rod to the frame, detaching the center shaft, and then drawing out both the drum and center shaft together.

In either prior art method, a special tool, such as the extension rd, must be provided and also a space for housing this tool must be provided in the frame. Therefore, the size of the frame becomes undesirably larger.

Furthermore, a maintenance person is required to expend much labor to attach and detach the tool every time the drum is loaded/unloaded. PG,3

In addition, such electro-photographic apparatus is generally provided with an electric power switch which cooperates with the opening/closing of a front door thereof so that the power supply is cut when the door is opened. In the case where the tool is housed within the frame, and a maintenance person forgets to store the tool in the frame, the front door must be opened once again, and restarting the apparatus is undesirably delayed. This delay includes not only the time required for opening and closing the door, but also warm-up time.

Accordingly, it is an object of this invention to provide a method and an apparatus for loading/unloading a drum member relative to a frame easily and without substantial labor.

It is another object of this invention to provide a method and an apparatus for loading/unloading a drum member relative to a frame without requiring extra space for housing a tool in the frame.

To achieve the foregoing and other objects of the present invention and in accordance with the purposes of the invention, there is provided an apparatus for loading/unloading a drum member and a related method.

The apparatus includes: a center shaft secured at one end to a frame; an inner support member slidably attached to the center shaft; and a drum member having an inner diameter substantially equal to the outer diameter of the inner support member and being rotatable on and slidable along the center shaft.

The method includes the steps of: providing a center shaft secured at one end to the frame; providing an inner support member slidably attached to the center shaft; providing a drum member supported at its inner surface by the inner support member and being slidable along the center shaft axis; drawing out the inner support member for a predetermined length toward the outside of the frame; and drawing out the drum member toward the outside of the frame, while using the inner support member as a guide.

According to this apparatus and method, the drum can be drawn out easily and safely by using the inner support member as a guide.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1A is a cross-sectional view showing the apparatus of the present invention with the drum loaded according to the present invention.

FIG. 1B is a cross-sectional view showing the drum being unloaded according to the present invention.

FIG. 1C is a cross-sectional view showing a final step in the unloading of the drum according to the present invention.

FIG. 2 is a partial cross-sectional view of a first embodiment of an electro-photographic apparatus according to the present invention.

FIG. 3 is a partially enlarged cross-sectional view of the electro-photographic apparatus shown in FIG. 2.

FIG. 4A is a partial side view of one end of the center shaft of the embodiment shown in FIG. 2.

FIG. 4B is a flattened circumferential view of FIG. 4A.

FIG. 5 is a partially enlarged cross-sectional view of a drive flange of the embodiment shown in FIG. 2.

FIG. 6 is a partial perspective view of an inner support member of the embodiment shown in FIG. 2.

FIG. 7 is a partial cross-sectional view of a second embodiment of an electro-photographic apparatus according to the present invention.

FIG. 8 is a partially enlarged cross-sectional view of a third embodiment of an electro-photographic apparatus according to the present invention.

FIG. 9 is a partially enlarged cross-sectional view of a fourth embodiment of an electro-photographic apparatus according to the present invention.

FIGS. 1A-1C illustrate generally the present invention, including: a center shaft 2 is secured at a first end 2a to a portion of the frame 1, an inner support member 4 is attached to the center shaft 2 such that it is slidable in the direction of the axis of the center shaft 2 as indicated by an arrow BA; and a drum 3, having an inner diameter substantially the same as the outer diameter of the inner support member 4. Members 5a and 5b are parts of the front of the frame 1 of the apparatus.

When the apparatus is in operation, both the inner support member 4 and the drum 3 are housed within the frame 1 as shown in FIG. 1A. When the drum 3 is required to be unloaded, the inner support member 4 and the drum 3 are drawn out in the direction A for a predetermined length, as shown in FIG. 1B, and then the drum 3 is further drawn out in the direction A, while using the inner support member 4 as a guide, as shown in FIG. 1C. When re-loading of the drum 3 is required, the reverse steps are followed.

FIG. 2 shows a partial, cross-sectional elevational view of a first embodiment of the present invention. A center shaft 11 is secured at a first end 11a to a part 12a of the frame 12, and detachably secured at its second, opposite end 11b to the front 12b of the frame via a cover assembly 14. An inner support member 18 is attached to the center shaft 11 via flanges 18a and 18d thereof and is slidable in the direction of the axis of the center shaft 11 as indicated by an arrow CE. A coil spring 21 is provided on the center shaft 11, between a stopper 19 secured to the center shaft by a screw 20 and the flange 18a, so that the spring 21 forces the inner support member 18 toward the outside of the frame 12, namely in the direction indicated by arrow G. The outer diameter of the inner support member 18 is almost equal to the inner diameter of a drum member 10 so that the outer surface 18f of the inner support member 18 can support and guide the inner surface 10b of the drum member 10.

This drum member 10 is, for example, a latent image developing drum for an electro-photographic printing apparatus, coated with a photosensitive material at its outer surface. Many associated known devices required to develop the latent image, such as a corona charger, a toner developer device, an optical system, a preclean corona decharger etc., are omitted from the figure for simplicity and convenience.

When rotated in operation, the drum member 10 is sandwiched and supported between a drive flange 13 and a support flange 15. The drive flange 13, as shown more in detail in FIG. 5, has a tapered rim 13b and a timing gear 13c. The rim 13b is partially inserted into a first end 10c of the drum member 10. The timing gear 13c is connected to a timing gear 41 of a motor 40 via a timing belt 36. The drive flange 13 is rotatable around the center shaft 11 by means of bearings 34 and 35.

The support flange 15 is a part of the cover assembly 14, as shown more in detail in FIG. 3. The cover assembly 14 consists of: a sleeve 25 having an inner diameter substantially the same as the outer diameter of the center shaft 11; the support flange 15 provided at a first end 25a of the sleeve 25 with a bearing 24; a coil spring 17 provided between the support flange 15 and a stopper washer 29 for forcing the support flange 15 toward the first end 25a, namely in the direction C of the arrow CE; a stopper pin 28 pierced through the sleeve 25; a knob 27 secured at the second end of the sleeve 25; and a cover plate 16 for covering an aperture 23 (FIG. 2) of the front 12b of the frame 12 for drawing the drum member 10 outside the frame 12. The cover plate 16 has one or more positioning holes 16a which receive respective positioning pins 12c of the frame 12. Furthermore, a coil spring 32 is provided on the sleeve 25 between the cover plate 16 and the knob 27 for forcing the cover plate 16 in the direction C of the arrow CE. Members 26a, 26b - and 33 are washers working as stoppers. A tapered rim 15a of the support flange 15 is partially inserted into the second end 10a of the drum member 10.

The center shaft 11 in this embodiment is a pipe, at the second, free end 11b of which there is provided a pair of grooves 31, each having an open portion 31a and a closed portion 31b. The width of the groove 31 is substantially the same as the diameter of the stopper pin 28. FIG. 4A shows a side view of the second end 11b of the center shaft 11 including the groove 31. FIG. 4B shows a flattened view of the circumferential structure of the grooves 31. The groove 31 and the stopper pin 28 form a lock means.

The unloading operation will be explained by referring to FIGS. 2, 3 and 4.

(1) First, by the user pushing the knob 27 in the direction C and then rotating the knob 27 counterclockwise, namely the direction D of the arrow DF, both ends 28a and 28b of the stopper pin 28 are guided along the grooves 31 toward the open portion 31a, and the cover assembly 14 is unlocked from the center shaft 11.

(2) By drawing out the knob 27 in the direction E, the whole cover assembly 14 is removed from the apparatus.

(3) By then removing the sleeve 25 and the support flange 15, the inner support member 18 is pushed out in the direction E by the spring 21 and ejected outside the frame 12 a predetermined length, as shown by a dotted line 18e in FIG. 2, which length can be defined by the position of a stopper screw 22. At the same time, the drum member 10 is also disengaged from the support flange 15, and may be moved with the inner support member 18 due to the friction between them.

(4) Then, the drum member 10 can be further drawn out in the direction E by using the ejected inner support member 18 as a guide means without hitting peripheral devices, because the end of the inner support member 18 is ejected outside of the part 12b of the frame 12.

(5) For re-loading the drum member 10 after it is cleaned, or for loading a new drum member 10, the reverse procedure is carried out. Namely, the drum member 10 is guided by and engaged with the inner support member 18 positioned outside the frame.

(6) Then, while pushing the inner support member 18, together with the drum member 10, inside the frame 12 against the force of the spring 21, the cover assembly 14 is attached to the center shaft 11.

(7) While engaging the stopper pin 28 with the open portion 31a of the groove 31 of the center shaft 11, the cover assembly 14 together with the inner support member 18 and the drum member 10 is further pushed inside while the user rotates the knob 27 in a clockwise direction. Upon hitting the closed portion 31b, the user releases the knob 27, the cover assembly 14 is locked to the center shaft 11, and the drum member 10 is supported between the drive and support flanges, 13 and 15, respectively.

(8) By engaging each positioning hole 16a with each positioning pin 12c, the cover plate 16 is positioned and secured to the frame 12 by the spring 32.

The inner support member 18 also can be removed from the center shaft 11, since the flange 18a has a recess 18c, as shown in FIG. 6, for clearing the stopper screw 22. The diameter of an aperture 18b of the flange 18a is substantially the same as the outer diameter of the center shaft 11. To ensure the stopper function of the stopper screw 22, the inner support member 18 must be rotated, preferably 180.degree., after being inserted on the center shaft 11.

The length of the center shaft 11 is substantially the same as the length of the drum member 10 in the above embodiment, but this is not necessarily required. For example, the center shaft 11 may be shorter than the drum member 10 if the sleeve 25 of the cover assembly 14 is long enough, and still the inner support member 18 can be ejected as its second end comes outside the front 12b of the frame 12. In any case, in order to guide the drum member 10 outside of the front 12b, the total length of the center shaft 11 and the inner support member 18 must be longer than the length of the drum member 10.

In the above embodiment, the inner support member 18 is a dummy drum which has no function during normal operation of the apparatus. But this inner support member 18 can be used as a heater drum for eliminating any non-uniformity of the temperature of the drum member 10. FIG. 7 shows such a heater drum 50, wherein similar reference numerals represent the similar parts shown in FIG. 2. The heater drum 50 has a heater winding 51 at its inner surface, and lead wires 53 extending through the inside of the center shaft 11 via a hole 11c and a connector 52.

The drive flange 13 of the first embodiment is described as being driven by the timing belt 36, but this is not necessarily required. For example, a series of gears can be used instead of the timing belt. In such a case, the drive flange can be integrated with the inner support member as shown in FIG. 8. In this figure, 60 is an integrated inner support member having an inner drum portion 61 and a drive flange portion 62. The drive flange portion 62 has a gear portion 62c and bearings 65 and 66. An intermediate gear 63 is provided between the center shaft 11 and the motor 40, supported by a bearing 64. The gear 63 has two gear portions 63a and 63b. The edges of both the gear portions 63b and 62c are tapered so that they can be easily reengaged when the disengaged inner support member 60 is pushed back in the direction shown by arrow H upon reloading of the drum member 10. The remaining members not shown in FIG. 8 are substantially the same as in FIG. 2. When the drum member 10 is required to be unloaded, the drum member 10 and the inner support member 60 are simultaneously drawn out for a predetermined length, and then only the drum member 10 is further drawn out by using the inner drum portion 61 as a guide means.

Furthermore, as shown in FIG. 9, a flange portion 10d at the outside of the drum member 10 and a coil spring 70 between this flange 10d and the flange 18d of the inner support member 18 can be provided, so that the drum member 10 is pushed out simultaneously as the inner support member is pushed out by the spring 21, when the cover assembly 14 is removed.

The inner support member 18 is not necessarily a drum, namely it need not have a cylindrical outer surface. It can be a member having a cross-like or a star-like cross section as long as it can support and guide the inner surface of the drum member 10.

Furthermore, it is also possible to provide an inner support member as a sleeve having an outer diameter close to the outer diameter of the center shaft 11, rather than close to the outer diameter of the drum member 10 as in the case of FIG. 2, and to provide a drum member with flanges having an inner diameter substantially the same as the outer diameter of the sleeve.

The foregoing is considered illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. Accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention and the appended claims.