EP1223475B1

EP1223475B1 - Driving force transmitting apparatus and image formation apparatus having the same

Info

Publication number: EP1223475B1
Application number: EP20020000264
Authority: EP
Inventors: Hiroshi Ishii
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2001-01-16
Filing date: 2002-01-15
Publication date: 2003-10-29
Anticipated expiration: 2022-01-15
Also published as: JP3832815B2; DE60200072T2; EP1223475A1; JP2002303337A; DE60200072D1

Description

FIELD OF THE INVENTION

The present invention relates to an image formation apparatus such as a copy machine, a facsimile machine, a printer and a composite machine thereof. The invention also relates to, in such an image formation apparatus, a driving force transmitting apparatus which transmits a driving force of a driving motor to an image carrier, a developing apparatus, a toner supplying apparatus, a paper feed roller, a transfer roller, a resist roller, a fixing apparatus and the like.

BACKGROUND OF THE INVENTION

In a conventional driving force transmitting apparatus of the image formation apparatus having a clutch in a gear train, as shown in Fig. 7 for example, a metal detent member 3 engages a projection 2 of the clutch 1, the detent member 3 is separately mounted to a frame 5 by means of a mounting screw 4, thereby preventing the clutch 1 from being rotated on a rotation shaft 6.

In such a conventional driving force transmitting apparatus, however, since the metal detent member 3 is provided separately from the metal frame 5, there are problems that the number of parts is increased, which also increases cost and weight of the apparatus.

There is another conventional driving force transmitting apparatus as shown in Fig. 8 for example . In this driving force transmitting apparatus, a resin frame 5 is integrally formed with a cylindrical section 7, and an outer periphery of the cylindrical section 7 is partially formed with a notch 7a. On an inner surface of the cylindrical section 7, an inwardly projecting engaging section 7b is formed straightly in an axial direction of the cylindrical section 7. A rotation shaft 6 is inserted into the cylindrical section 7 such that the rotation shaft 6 passes through the resin frame 5 from the inner surface side.

The rotation shaft 6 is inserted into a center hole of a clutch gear 8 which constitutes a gear train (not shown). The rotation shaft 6 is also inserted into a center of the clutch 1 to support the clutch gear 8 and the clutch 1 inserted into the cylindrical section 7. The clutch gear 8 engages another gear constituting the gear train through the notch 7a, and the engaging section 7b of the cylindrical section 7 is inserted into an engaging groove 2a of the projection 2, thereby preventing the clutch 1 from being rotated.

If the clutch 1 is energized, the clutch 1 transmits rotation of the clutch gear 8 to the rotation shaft 6, and if the energization is cut, the transmission of the rotation from the clutch gear 8 to the rotation shaft 6 is stopped.

The resin frame 5 is integrally formed with the engaging section 7b which engages the clutch 1 and prevents the rotation thereof. Therefore, in a driving force transmitting apparatus used for the image formation apparatus, for example, the clutch 1 is prevented from rotating without providing an independent detent member for the clutch, thereby decreasing the number of parts, and the frame 5 integrally provided with the engaging section 7b is made of resin, thereby reducing the weight.

In the conventional driving force transmitting apparatus shown in Fig. 8, however, since the resin frame 5 must be made of hard material, the frame 5 is made of polyphenylene ether (PPE) or the like including glass fiber. In order to obtain sufficient strength, a portion of the clutch 1 which prevents the rotation is formed into a cylindrical shape to form the cylindrical section 7.

This conventional driving force transmitting apparatus has the following problems.

1) An outer diameter of the clutch gear 8 must be smaller than that of the clutch 1 so that the clutch 1 can be accommodated in the cylindrical section 7 and thus, a design of the apparatus is limited.

2) In order to bring another gear into engagement with the clutch gear 8, the cylindrical section 7 must be formed with the notch 7a, which complicates its shape, and increases a cost of a mold and thus a cost of the entire apparatus.

3) If the clutch gear 8 engages a plurality of gears, the notch 7a must be formed larger or the number of notches must be increased, which lowers the strength of the cylindrical section 7.

4) Since a gear which engages with the clutch gear 8 is not allowed to abut against the clutch 1, which limits a thrust direction of the gear which engages the clutch gear 8.

SUMMARY OF THE INVENTION

The present invention has been achieved in order to solve the above problems in a driving force transmitting apparatus using a clutch. It is a first object of this invention to simplify a design of the apparatus, decrease a cost of the apparatus, secure sufficient strength, and reliably prevent the clutch on a rotation shaft from being rotated with respect to the rotation shaft.

In the driving force transmitting apparatus using the clutch, it is a second object of this invention to limit a movement of the clutch in a thrust direction of the rotation shaft without providing a separate E-ring or detent ring, thereby decreasing the number of parts and weight of the apparatus.

It is a third object of this invention to make it easy to attach and detach the clutch to a resin frame.

It is a fourth object of this invention to prevent the clutch from being rotated without increasing the size of the driving force transmitting apparatus using the clutch.

It is a fifth object of this invention to prevent the strength of the resin frame from being largely lowered.

It is a sixth object of this invention to provide an image formation apparatus having the driving force transmitting apparatus which can achieve the above objects.

To achieve the first object, according to a first aspect of the present invention, there is provided a driving force transmitting apparatus comprising a clutch on a rotation shaft which passes through a resin frame and a clutch gear having an outer diameter larger than that of the clutch, wherein the resin frame is integrally formed with a stand-up piece, the stand-up piece is provided with an engaging section which engages with the clutch to prevent the clutch from rotating.

To achieve the second object, according to a second aspect of the present invention, there is provided a driving force transmitting apparatus comprising a clutch on a rotation shaft which passes through a resin frame and a clutch gear having an outer diameter larger than that of the clutch, wherein the resin frame is integrally formed with a stand-up piece, the stand-up piece is provided with an engaging section which engages with the clutch to restrain the clutch from moving in a thrust direction thereof.

To achieve the third object in addition to the first or second object, a third aspect of the present invention provides the driving force transmitting apparatus according to the first or second aspect, wherein the engaging section is engaged with or disengaged from said clutch using resilience of said stand-up piece.

To achieve the fourth object in addition to any one of the first to third objects, a fourth aspect of the present invention provides the driving force transmitting apparatus according to the first, second, or third aspect, wherein the engaging section engages the clutch at a position inward of an outer diameter of the clutch gear.

To achieve the fifth object in addition to any one of the first to fourth objects, a fifth aspect of the present invention provides the driving force transmitting apparatus according to the first, second, third or fourth aspect, wherein the resin frame is formed with a reinforcing rib.

To achieve the sixth object, according to a sixth aspect of the present invention, there is provided an image formation apparatus having the driving force transmitting apparatus according to the first, second, third, fourth or fifth aspect.

Other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram which shows an inside structure of a laser copier;

Fig. 2 is a perspective view of a pair of resin frames provided in the copier body;

Fig. 3 is an exploded perspective view of a driving force transmitting apparatus of the invention to be mounted to one of the resin frames;

Fig. 4A is a perspective view which shows a state in which a clutch is mounted to the resin frame, Fig. 4B is a partial perspective view of the resin frame and Fig. 4C is a perspective view which explain attaching and detaching operation of the clutch to and from the resin frame;

Fig. 5 is an exploded perspective view of another example of a state in which the clutch is mounted to the resin frame;

Fig. 6A is a perspective view of another example of a state in which the clutch is mounted to the resin frame, and Fig. 6B is a vertical sectional view of the resin frame;

Fig. 7 is a partial perspective view of a conventional driving force transmitting apparatus having a clutch; and

Fig. 8 is a partial perspective view of another conventional driving force transmitting apparatus having a clutch.

DETAILED DESCRIPTIONS

Embodiments of the present invention will be explained below with reference to the drawings.

Fig. 1 is a schematic diagram which shows an inside structure of a laser copier.

A reference number 50 represents a copier body. An automatic paper feeder 53 is mounted on the copier body 50 such that the automatic paper feeder 53 covers a contact glass 52 on an image reader 51 and the automatic paper feeder 53 can be opened and closed.

When making copies using the laser copier, original draft copies are set on the automatic paper feeder 53, or the automatic paper feeder 53 is opened and the original draft copies are set directly on the contact glass 52, and a start switch provided on an operating section (not shown) is pushed.

If the original draft copies were set on the automatic paper feeder 53, contents of the original draft copies transferred onto the contact glass 52 by the automatic paper feeder 53 are read by the image reader 51, and if the original draft copies were set directly on the contact glass 52, contents of the original draft copies on the contact glass 52 are-read by the image reader 51.

A drum-shaped image carrier 55 is rotated clockwisely, and a surface of the image carrier 55 is allowed to become charged uniformly using an electrifying apparatus 56. Then, laser light is applied by an optical writing apparatus 57 in accordance with the contents readby the image reader 51, thereby carrying out the writing operation, and an electrostatic latent image is formed on a surface of the image carrier 55. Then, toner is allowed to adhere using a developing apparatus 58 to bring the electrostatic latent image into a visible image, and the image is formed on the image carrier 55.

A paper feed roller 60 is rotated to send a sheet from a paper feed cassette 61, the sheet is transferred by a transfer roller 63 through a transfer path 62, and a tip end is brought into abutment against a resist roller 64. Alternatively, a paper feed 65 is rotated to send a manual sheet from a manual tray 66, and the sheet is transferred through the transfer path 62, and a tip end of the sheet is brought into abutment against the resist roller 64.

The resist roller 64 is rotated in accordance with timing of an image on the image carrier 55, the sheet is sent under the image carrier 55, and the image on the image carrier 55 is copied by a copy-transfer apparatus 67 on the sheet. After the image was copied on the sheet, the sheet is transferred into a fixing apparatus 68 by the copy-transfer apparatus 67, the copied image is fixed by the fixing apparatus 68, and the sheet is discharged out from the copier body 50 by a discharge roller 69.

When an image is formed also on a back surface of the sheet, the sheet on which the image was fixed is brought into a double-sided storage apparatus 70, where the sheet is reversed and again sent into the transfer path 62, and the separately formed image on the image carrier 55 is copied on the back surface of the sheet, the copied image is fixed and then, double-sided copied sheet is discharged out from the copier body 50 by the discharge roller 69.

The front surface of the image carrier 55 after the image was copied is cleaned by a cleaning apparatus 71, residue toner is removed, and diselectrified by a diselectrifying apparatus (not shown), and the front surface is brought into a standby state of the image formation operation starting from the electrifying operation.

In the laser copier, as shown in Fig. 2, a pair of resin frames 10 are mounted and fixed on base frames (not shown) provided at front and back portions in the copier body 50. The image carrier 55, the electrifying apparatus 56, the optical writing apparatus 57, the developing apparatus 58, the

paper feed rollers

60, 65, the transfer roller 63, the resist roller 64, the copy-transfer apparatus 67, the fixing apparatus 68, the discharge roller 69, the double-sided storage apparatus 70, the cleaning apparatus 71 and the like are supported between the

frames

10 and 10.

Fig. 3 shows one of the pair of resin frames 10 on which a driving force transmitting apparatus of the invention is mounted.

The resin frame 10 is made of polybutylene terephthalate (PBT), and gear shafts 11 are integrally formed on an outer side of the resin frame 10. A gear 12 is rotatably mounted to each of the gear shafts 11.

The resin frame 10 is provided with rotation shafts 20. The gears 12 and later-described clutch gears 12a to be mounted to the rotation shafts 20 constitute a gear train 13. Although it is not shown, the gear train 13 transmits a driving force of a driving motor (not shown) to the image carrier 55, the developing apparatus 58, a toner supplying apparatus which supplies toner to the developing apparatus 58, the

paper feed rollers

60, 65, the transfer roller 63, the resist roller 64, the fixing apparatus 68 and the like.

In the shown example, the gear shafts 11 of the plurality of gears 12 constituting the gear train 13 are integrally formed on the resin frames 10 which support the gear train 13. Therefore, in the driving force transmitting apparatus, it is possible to rotatably support the gears 12 without providing independent gear shaft, thereby reducing the number of parts. Since the frames 10 which integrally include the gear shafts 11 are made of resin material, the weight of frames 10 can be reduced.

In the shown example, reinforcing ribs 14 are integrally formed on periphery of the resin frame 10 and the entire frame 10 is formed into a box-like shape. Therefore, the strength of the frame 10 is enhanced, and it is possible to prevent the strength of the frame from being largely deteriorated although resin material is used. Of course, positions of the reinforcing ribs 14 are not limited to the periphery of the resin frame 10, and the ribs may be formed on appropriate positions.

In the example shown in Fig. 3, the gear train 13 is provided with clutches 16. Each of the clutches 16 is rotatably provided on a rotation shaft 20 which passes through the resin frame 10 together with a clutch gear 12a. An outer . diameter d of the clutch gear 12a is larger than that an outer diameter D of the clutch 16.

The clutch 16 is provided on a rotation shaft of the toner supply roller which supplies toner to the developing apparatus 58, the

paper feed rollers

60, 65 or the transfer roller 63 which requires control of rotating or stopping the rotation shaft.

Fig. 4A shows another state where the clutch 16 is mounted to the resin frame 10. Fig. 4B shows a portion of the resin frame 10. Fig. 4C shows a case in which the clutch 16 is attached or detached to or from the resin frame 10.

In the example shown in Fig. 4, a standing-up piece 24 is integrally formed on the resin frame 10 such that the standing-up piece 24 stands up at right angles with respect to an outer plate surface of the resin frame 10 in parallel to the rotation shaft 20. The standing-up piece 24 is provided at its tip end with a projecting engaging section 25, and a through hole 26 is formed in the resin frame 10 adjacently to the standing-up piece 24. The rotation shaft 20 is inserted into the through hole 26 from inside, and the rotation shaft 20 is allowed to pass through the center hole of the clutch gear 12a which constitutes the gear train 13. The rotation shaft 20 is also inserted into the center of the clutch 16, and the clutch gear 12a and the clutch 16 are supported on the outer side of the resin frame 10.

The standing-up piece 24 is formed long, and is bent using resilience of its own as shown in Fig. 4C. With this structure, the engaging section 25 is engaged into a retaining groove 22 of a projection 21 of the clutch 16 to prevent the clutch 16 from being rotated. When the clutch 16 is to be detached from the resin frame 10, the standing-up piece 24 is bent as shown with a chain line in Fig. 4A, the engagement between the projection 21 of the clutch 16 and the engaging section 25 of the standing-up piece 24 is released.

In the shown example, the engaging section 25 is engaged with and disengaged from the clutch 16 using the resilience of the engaging section 25 itself. Therefore, it is unnecessary to fasten or unfasten a mounting screw, and it is possible to eliminate the necessity of the mounting screw and the like, thereby reducing the number of parts, and it is possible to facilitate the attaching and detaching operation of the clutch 16 with respect to the resin frame 10.

In the shown example, by increasing the height h of the engaging section 25, the engaging section 25 engages the clutch 16 at a position inward of the outer diameter of the clutch gear 12a. With this design, rotation of the clutch 16 can be prevented without increasing the size of the apparatus.

In the example shown in Figs.4, the rotation of the clutch 16 is prevented by the engaging section 25, but it is not possible to restrain the clutch 16 from moving in a thrust direction of the rotation shaft 20. Thereupon, when it is necessary to restrain the movement of the clutch 16 in the thrust direction, the engaging section 25 of the standing-up piece 24 is formed into a mouth-like shape so that the projection 21 of the clutch 16 can be inserted into the engaging section 25.

In an example shown in Fig. 5, the engaging section 25 which engages the clutch 16 and restrains the movement thereof in the thrust direction (direction of arrow "a" in Fig. 5) is integrally formed on the resin frame 10. With this design, the rotation of the clutch 16 can be prevented by the engaging section 25, and the movement thereof in the thrust direction can also be restrained. Therefore, the movement of the clutch 16 in the thrust direction a can be restrained without providing a separate E-ring or detent ring, the number of parts can be reduced, the frame 10 integrally provided with the engaging section 25 is made of resin to reduce the weight.

In an example shown in Figs.6, a basket-like engaging section 28 is integrally formed on the outer side of the resin frame 10, opposed through

holes

29 and 30 are respectively formed in the resin frame 10 and the engaging section 28, and a window 31 is formed in an outer periphery of the engaging section 28. The rotation shaft 20 which passes through the through

holes

29 and 30 is allowed to pass through the clutch gear 12a, the rotation shaft 20 is inserted into the clutch 16, the clutch gear 12a and the clutch 16 are accommodated and supported in the engaging section 28. At that time, the projection 21 of the clutch 16 is put into the window 31.

With the above structure also, the rotation of the clutch 16 can be prevented by the window 31 of the engaging section 28, and the movement thereof in the thrust direction (in the direction of arrow "a" in Fig. 6) can also be restrained by the resin frame 10 formed with the engaging section 28. Therefore, the movement of the clutch 16 in the thrust direction a can be restrained without providing a separate E-ring or detent ring, the number of parts can be reduced, the frame 10 integrally provided with the engaging section 28 is made of resin to reduce the weight.

As explained above, according to the first aspect of the invention, the resin frame is integrally formed with a stand-up piece, the stand-up piece is provided with an engaging section which engages with the clutch to prevent the clutch from rotating. Therefore, in the driving force transmitting apparatus using the clutch, the clutch is prevented from rotating by means of the stand-up piece without providing an independent clutch detent member, thereby decreasing the number of parts, and the frame integrally provided with the engaging section is made of resin, thereby reducing the weight.

The stand-up piece which prevents the rotation of the clutch does not cover around the clutch gear. Therefore, the outer diameter of the clutch gear is not limited, the clutch gear can be made larger than the clutch, a shape of a mold of the resin frame is not complicated, sufficient strength of the resin frame can be secured, and the outer diameter of the clutch gear can be made larger than that of the clutch. Therefore, it is unnecessary to limit the movement of the gear which engages the clutch gear in its thrust direction.

With the above structure, it is easy to design the apparatus, sufficient strength can be secured inexpensively, and it is possible to reliably prevent the clutch on the rotation shaft from being rotated together with the rotation shaft.

According to the second aspect of the invention, the resin frame is integrally formed with a stand-up piece, the stand-up piece is provided with an engaging section which engages with the clutch to restrain the clutch from moving in a thrust direction thereof. Therefore, in the driving force transmitting apparatus using the clutch, the clutch is restrained from moving in the thrust direction of the rotation shaft without providing a separate E-ring or detent ring, thereby decreasing the number of parts, and the frame integrally provided with the engaging section is made of resin, thereby reducing the weight.

According to the third aspect of the invention, the engaging section is engaged with or disengaged from the clutch using resilience of the stand-uppiece. Therefore, in addition to the effect of the first or second aspect, it is unnecessary to fasten or unfasten a mounting screw, and it is possible to eliminate the necessity of the mounting screw and the like, thereby reducing the number of parts, and it is possible to facilitate the attaching and detaching operation of the clutch with respect to the frame.

According to the fourth aspect of the invention, the engaging section engages the clutch at a position inward of an outer diameter of the clutch. Therefore, in addition to the effect of any one of the first to third aspects, the clutch can be prevented from rotating without increasing its size.

According to the fifth aspect of the invention, the resin frame is formed with a reinforcing rib. Therefore, in addition to the effect of any one of the first to fourth aspects, the strength is enhanced, the resin is used instead of metal and thus, the strength of the frame can be prevented from being largely deteriorated.

According to the sixth aspect of the invention, an image formation apparatus has the driving force transmitting apparatus according to any one of the first to fifth aspects. Therefore, it is possible to provide the image formation apparatus having the driving force transmitting apparatus which can exhibits the above-described effect.

Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.

Claims

A driving force transmitting apparatus comprising a clutch (16) on a rotation shaft (20) which passes through a resin frame (10) and a clutch gear (12) having an outer diameter larger than that of said clutch (16), wherein
said resin frame (10) is integrally formed with a stand-up piece (24) the stand-up piece (24) is provided with an engaging section (25) which engages with said clutch(16) to prevent said clutch(16) from rotating.
A driving force transmitting apparatus comprising a clutch (16) on a rotation shaft (20) which passes through a resin frame (10) and a clutch gear (12) having an outer diametcr larger than that of said clutch (16), wherein
said resin frame (10) is integrally formed with a stand-up piece (24), the stand-up piece (24) is provided with an engaging section (25) which engages with said clutch (16) to restrain said clutch (16) from moving in a thrust direction thereof.
The driving force transmitting apparatus according to claim 1 or 2, wherein said engaging section (25) is engaged with or disengaged from said clutch (16) using resilience of said stand-up piece (24).
The driving force transmitting apparatus according to claim 1, 2 or 3, wherein said engaging section (25) engages said clutch (16) at a position inward of an outer diameter (d) of said clutch gear (12).
The driving force transmitting apparatus according to claim 1, 2, 3, or 4, wherein said resin frame (10) is formed with a reinforcing rib (14).
An image formation apparatus having the driving force transmitting apparatus according to claim 1, 2, 3, 4 or 5.