Drive mechanism and image forming apparatus provided with the same

A drive mechanism of the present invention includes: a housing part composed of a first resin cover and a second resin cover; a first sheet metal member housed in the housing part; a first rotation transmission wheel group disposed on the first sheet metal member on a side directed to the first resin cover; a second rotation transmission wheel group disposed on the first sheet metal member on a side directed to the second resin cover; a positioning part rotatably supporting a first rotation transmission wheel of the first rotation transmission wheel group; and a pin member positioned by inserting into the positioning part via the first resin cover.

This application is based on and claims the benefit of priority from Japanese Patent Application No. 2010-083905, filed on 31 Mar. 2010, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a drive mechanism and an image forming apparatus provided with the same.

2. Related Art

An image forming apparatus such as a copy machine, a printer, a facsimile machine and the like generally includes: a plurality of image supporting units (photoreceptor drums); a developing unit that transforms an electrostatic latent image formed on an image supporting unit to a toner image; an image transfer part that transfers the toner image formed on the image supporting unit to an object such as paper; and a fixing part that fixes the toner image transferred to the object.

There is a demand for an image forming apparatus of higher image quality and lower price. Accordingly, a structure for maintaining high dimensional accuracy is required in a drive mechanism to fulfill such a demand.

As a drive mechanism of high dimensional accuracy, for example, a drive mechanism has been proposed that includes: a sheet metal part; a shaft rotatably supported by the sheet metal part; a drum part rotatably supported by the shaft; and a driving part firmly attached to sheet metal, in which a drive gear attached to an output shaft of the driving part is engaged with a driven gear attached to the drum part. With such a drive mechanism, since the driving part and the shaft are attached to the sheet metal part, an interaxial distance between the drive gear and the driven gear is highly accurate.

SUMMARY OF THE INVENTION

In the abovementioned drive mechanism, in a case where the driving part and the shaft are covered only with the sheet metal part, grease injected to the driving gear and the driven gear may scatter and adhere to other units and components. In addition, in a case where the driving part and the shaft are covered only with a resin member, the interaxial distance between the driving gear and the driven gear may change or axial inclination may arise in the driving gear and the driven gear.

The present invention relates to a drive mechanism that includes a first resin cover, a second resin cover, a housing part, a first sheet metal member, a first rotation transmission wheel group, a second rotation transmission wheel group, a second sheet metal member, at least one positioning part and at least one pin member. The first resin cover has a first concave part opening toward a first face. The second resin cover has a second concave pare opening toward the first resin cover, and is disposed such that a periphery of the second concave part is aligned to come into contact with a periphery of the first concave part. The housing part includes the first concave part and the second concave part. The first sheet metal member is disposed inside the housing part. The first rotation transmission wheel group has at least one first rotation transmission wheel, and is housed by the housing part and disposed on the first sheet metal member on a side directed to the first resin cover. The second rotation transmission wheel group is housed by the housing part and disposed on the first sheet metal member on a side directed to the second resin cover. The second sheet metal member is disposed on the first resin cover on a side opposite to the second resin cover and disposed opposite to the first sheet metal member interposing the first resin cover therebetween. At least one positioning part is formed like a through hole in the first sheet metal member and rotatably supports the at least one first rotation transmission wheel. At least one pin member is installed upright on the second sheet metal member on a side directed to the first sheet metal member and each pin member is inserted into each positioning part via the first resin cover such that each pin member is positioned.

According to the present invention, since the pin member is inserted into the positioning part formed on the first sheet metal member, the accuracy of the interaxial distance between adjacent first pin members is maintained. As a result, it is possible to reduce an occurrence of noise due to the engagement of teeth upon rotation of the first rotation transmission wheel and the second rotation transmission wheel.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the image forming apparatus according to the present invention will be described hereinafter with reference to the drawings. An overall structure of the printer1as an image forming apparatus according to a first embodiment is described referring toFIG. 1.FIG. 1is a front view illustrating an arrangement of components of the printer1as the first embodiment of the present invention.

Hereinafter, when viewed by a user standing in front of the printer1, a horizontal direction is a direction X, an anteroposterior direction (depth direction) is a direction Y, and a vertical direction is a direction Z.

As shown inFIG. 1, the printer1as the image forming apparatus includes: an apparatus main body M; an image forming unit GK that forms a toner image on a sheet of paper T as a sheet-shaped object based on predetermined image information, and a paper feeding/ejection unit KH that feeds the sheet of paper T to the image forming unit GK and ejects the sheet of paper T on which the toner image is formed. The external shape of the apparatus main body M is composed of a cabinet BD as a housing.

As shown inFIG. 1, the paper feeding/ejection unit KH includes a paper feeding cassette52, a manual feeding unit64, a paper feed path L for a sheet of paper T, a pair of resist rollers80, a plurality of rollers or roller pairs, and an discharging part50. It should be noted that, as will be described later, the paper feed path L is an assembly of a first paper feed path L1, a second paper feed path L2, a third paper feed path L3, a manual paper feed path La, and a reverse paper feed path Lb.

Components of the image forming unit GK and the paper feeding/ejection unit KH will be described in detail hereinafter.

First, a description is provided for the image forming unit GK. In the image forming unit GK, as the photoreceptor drums2a,2b,2cand2drotate during image formation, the following steps are performed in the following order on a surface of the photoreceptor drums2a,2b,2c, and2d; charging by the charging parts10a,10b,10c, and10d; exposure by the laser scanner units4a,4b,4c, and4d; development by the developing units16a,16b,16c, and16d; primary image transfer by the intermediate image transfer belt7and the primary image transfer rollers37a,37b,37c, and37d; static elimination by the static eliminators12a,12b,12c, and12d; and cleaning by the drum cleaning parts11a,11b,11c, and11d.

In addition, secondary image transfer by the intermediate image transfer belt7, the secondary image transfer roller8and the opposing roller18, and fixation by the fixing part9are performed in the image forming unit GK.

Each of the photoreceptor drums2a,2b,2c, and2dis composed of a cylindrically shaped member and functions as a photoreceptor or an image supporting unit. Each of the photoreceptor drums2a,2b,2c, and2dis disposed rotatable in a direction of an arrow shown inFIG. 1, about a rotational axis that extends in a direction orthogonal to a direction of movement of the intermediate image transfer belt7. An electrostatic latent image is formed on a surface of each of the photoreceptor drums2a,2b,2c, and2d.

Each of the charging parts10a,10b,10c, and10dis disposed to face the surface of each of the photoreceptor drums2a,2b,2c, and2d. Each of the charging parts10a,10b,10c, and10duniformly positively charge (straight polarity) the surface of each of the photoreceptor drums2a,2b,2c, and2d.

Each of the laser scanner units4a,4b,4c, and4d, which functions as an exposure unit, is disposed to be spaced apart from the surface of each of the respective photoreceptor drums2a,2b,2c, and2d. The laser scanner units4a,4b,4c, and4dare each configured to include a laser light source, a polygonal mirror, a polygonal mirror driving motor and the like, which are not illustrated.

Each of the laser scanner units4a,4b,4c, and4dscans and exposes the surface of each of the photoreceptor drums2a,2b,2c, and2d, based on image information input from an external apparatus such as a PC (personal computer). An electric charge of an exposed part of the surface of each of the photoreceptor drums2a,2b,2c, and2dis removed, which are scanned and exposed by the laser scanner units4a,4b,4c, and4d, respectively. In this way, an electrostatic latent image is formed on the surface of each of the photoreceptor drums2a,2b,2c, and2d.

The developing units16a,16b,16c, and16dare disposed to correspond to the photoreceptor drums2a,2b,2c, and2d, respectively, facing corresponding surfaces of the photoreceptor drums2a,2b,2c, and2d. Each of the developing units16a,16b,16c, and16dforms a toner image of each color on the surface of each of the photoreceptor drums2a,2b,2c, and2dby depositing toner of each color on a part where an electric charge is removed in an electrostatic latent image formed on the surface of each of the photoreceptor drums2a,2b,2c, and2d. The developing units16a,16b,16c, and16dcorrespond to four colors of yellow, cyan, magenta, and black, respectively. Each of the developing units16a,16b,16c, and16dincludes a developing roller disposed to face the surface of each of the photoreceptor drums2a,2b,2c, and2d, and stirring rollers for stirring toner, and the like.

The toner cartridges5a,5b,5c, and5dare provided correspond to the developing units16a,16b,16c, and16d, respectively, and store toners of different colors that are supplied to the developing units16a,16b,16c, and16d, respectively. The toner cartridges5a,5b,5c, and5dstore toners of yellow, cyan, magenta, and black respectively.

The toner feeding parts6a,6b,6c, and6dare provided to correspond to the toner cartridges5a,5b,5c, and5dand the developing units16a,16b,16c, and16d, respectively. The toner feeding parts6a,6b,6c, and6dsupply the toners of the respective colors stored in the toner cartridges5a,5b,5c, and5dto the developing units16a,16b,16c, and16d, respectively. The toner feeding devices6a,6b,6c, and6dare connected with the developing units16a,16b,16c, and16d, respectively, via toner delivery devices500a,500b,500cand500d.

The toner images of the colors formed on the photoreceptor drums2a,2b,2c, and2dare primarily transferred sequentially to the intermediate image transfer belt7. The intermediate image transfer belt7goes around a driven roller35, the opposing roller18operating of a driving roller, a tension roller36and the like. Since the tension roller36biases the intermediate image transfer belt7from inside to outside, a predetermined tension is applied to the intermediate image transfer belt7.

The primary image transfer rollers37a,37b,37c, and37dare disposed opposite to the photoreceptor drums2a,2b,2c, and2d, respectively, interposing the intermediate image transfer belt7therebetween.

The intermediate image transfer belt7is sandwiched between the primary image transfer rollers37a,37b,37c, and37dand the photoreceptor drums2a,2b,2c, and2d. The sandwiched parts are pressed against surfaces of the photoreceptor drums2a,2b,2c, and2d. Primary image transfer nips N1a, N1b, N1c, and N1dare formed between the photoreceptor drums2a,2b,2c, and2dand the primary image transfer rollers37a,37b,37c, and37d, respectively. At the primary image transfer nips N1a, N1b, N1c, and N1d, toner images of the respective colors formed on the photoreceptor drums2a,2b,2c, and2dundergo primary transfer sequentially onto the intermediate image transfer belt7. In this manner, a full-color toner image is formed on the intermediate image transfer belt7.

A primary image transfer bias is applied to each of the primary image transfer rollers37a,37b,37c, and37dby a primary image transfer bias application part (not illustrated). The primary image transfer bias transfers a toner image of each color formed on each of the photoreceptor drums2a,2b,2c, and2donto the intermediate image transfer belt7.

The static eliminators12a,12b,12c, and12dare disposed so as to face surfaces of the photoreceptor drums2a,2b,2c, and2d, respectively. The static eliminators12a,12b,12c, and12deach remove electricity (eliminate an electrical charge) from a surface of each of the photoreceptor drums2a,2b,2c, and2dafter the primary image transfer, by casting light on the surface of each of the photoreceptor drums2a,2b,2c, and2d.

The drum cleaning parts11a,11b,11c, and11dare disposed to face the surfaces of the photoreceptor drums2a,2b,2c, and2d, respectively. The drum cleaning parts11a,11b,11c, and11dremove toner and attached matter remaining on the surfaces of the photoreceptor drums2a,2b,2c, and2dafter the primary image transfer, respectively, and transfer the removed toner to a collection mechanism such that the toner is collected.

The secondary image transfer roller8causes the full-color toner image, which has been primarily transferred to the intermediate image transfer belt7, to be secondarily transferred to a sheet of paper T. A secondary image transfer bias is applied to the secondary image transfer roller8by a secondary image transfer bias application part (not illustrated). The secondary image transfer bias is a bias for transferring the full-color toner image formed on the intermediate image transfer belt7to the sheet of paper T.

The secondary image transfer roller8comes into contact with and departs away from the intermediate image transfer belt7selectively. More specifically, the secondary image transfer roller8is configured to be movable between a contact position at which it is in contact with the intermediate image transfer belt7and a spaced position at which it is spaced apart from the intermediate image transfer belt7. In particular, the secondary image transfer roller8is disposed at the contact position when it transfers the toner image primarily transferred to the surface of the intermediate image transfer belt7to the sheet of paper T. Under other circumstances it is disposed at the spaced position.

The opposing roller18is disposed opposite to the secondary image transfer roller8interposing the intermediate image transfer belt7therebetween. The intermediate image transfer belt7is sandwiched between the secondary image transfer roller8and the opposing roller18. The sheet of paper T is pressed against an outer surface (a surface to which the toner image is primarily transferred) of the intermediate image transfer belt7. A secondary image transfer nip N2is formed between the intermediate image transfer belt7and the secondary image transfer roller8. At the secondary image transfer nip N2, the full-color toner image primarily transferred to the intermediate image transfer belt7is secondarily transferred to the sheet of paper T.

The fixing part9fuses and pressurizes respective color toners forming the toner image that has been secondarily transferred to the sheet of paper T, such that the color toners are fixed on the sheet of paper T. The fixing part9includes a heating rotator9athat is heated by a heater, and a pressurizing rotator9bthat is brought into pressure contact with the heating rotator9a. The heating rotator9aand the pressurizing rotator9bsandwich and apply pressure to the sheet of paper T to which the toner image is secondarily transferred, and also feed the sheet of paper T. The sheet of paper T is fed while sandwiched between the heating rotator9aand the pressurizing rotator9b, so that the toner transferred to the sheet of paper T is fused and pressurized to be fixed to the sheet of paper T.

Next, the paper feeding/ejection unit KH is described. As shown inFIG. 1, the paper feeding cassette52for housing sheets of paper T is disposed in a lower part of the apparatus main body M. The paper feeding cassette52is configured to be manually drawn in a horizontal direction from the cabinet BD of the apparatus main body M. The paper feeding cassette52includes a paper tray60on which the sheets of paper T are placed. The paper feeding cassette52stores the sheets of paper T stacked on the paper tray60. A sheet of paper T placed on the paper tray60is fed to the paper feed path L by a cassette feeding part51disposed in an end part of the paper feeding cassette52on a side of feeding the paper (at a right end part ofFIG. 1). The cassette feeding part51includes a double feed prevention mechanism including: a forward feed roller61for picking up a sheet of paper T on the paper tray60; and a pair of paper feeding rollers81for feeding the sheet of paper T one at a time to the paper feed path L.

The manual feeding unit64is provided on a right lateral face (the right side inFIG. 1) of the apparatus main body M. The manual feeding unit64is provided primarily for the purpose of feeding other sheets of paper T that are different in size and type from the sheets of paper T stored in the paper feeding cassette52to the apparatus main body M. The manual feeding unit64includes the manual feeding tray65, which composes a portion of a right lateral face of the apparatus main body M when the manual feeding unit64is closed, and a paper feeding roller66. A lower end of the manual feeding tray65is rotatably attached in a vicinity of the paper feeding roller66(openable and closable). A sheet or sheets of paper T are placed on the manual feeding tray65while it is open. The paper feeding roller66feeds a sheet of paper T placed on the manual feeding tray65while it is open to the manual feeding path La.

The paper feed path L includes: the first paper feed path L1from the cassette feeding part51to the secondary image transfer nip N2; the second paper feed path L2from the secondary image transfer nip N2to the fixing part9; the third paper feed path L3from the fixing part9to the discharging part50; the manual paper feed path La that guides paper fed from the manual feeding unit64to the first paper feed path L1; and the reverse paper feed path Lb that reverses and returns the sheet of paper T that is fed from a downstream side to an upstream side in the third paper feed path L3to the first paper feed path L1.

In addition, a first junction P1and a second junction P2are provided in the middle of the first paper feed path L1. A first branch part Q1is provided in the middle of the third paper feed path L3. The first junction P1is where the manual paper feed path La joins the first paper feed path L1. The second junction P2is where the reverse paper feed path Lb joins the first paper feed path L1. The first branch part Q1is where the reverse paper feed path Lb branches off from the third paper feed path L3.

A paper detection sensor (not illustrated) for detecting a sheet of paper T and a pair of resist rollers80are disposed in the middle of the first paper feed path L1(more specifically, between the second junction P2and the secondary image transfer nip N2). The paper detection sensor is disposed immediately before the pair of resist rollers80in a feed direction of the sheet of paper T (upstream of the feed direction). The pair of resist rollers80performs skew compensation of the sheet of paper T and timing adjustment with respect to formation of a toner image in the image forming unit GK. The pair of resist rollers80performs the abovementioned compensation and the timing adjustment based on signal information detected by the paper detection sensor and feeds the sheet of paper.

A pair of intermediate rollers82is disposed between the first junction P1and the second junction P2in the first paper feed path L1. The pair of intermediate rollers82is disposed on a downstream side in the paper feed direction with respect to the pair of paper feeding rollers81. It sandwiches to feed a sheet of paper T, which is fed from the pair of paper feeding rollers81to the pair of resist rollers80.

A reverse paper feed path Lb causes a surface (an unprinted surface) opposite to a surface having already been printed to face the intermediate image transfer belt7, when duplex printing of a sheet of paper T is performed. The reverse paper feed path Lb reverses and returns the sheet of paper T, which is fed from the first branch part Q1toward the discharging part50, to the first paper feed path L1. Subsequently the reverse paper feed path Lb feeds the sheet of paper T to upstream of the pair of resist rollers80, which is disposed upstream of the secondary image transfer roller8. At the secondary image transfer nip N2, a toner image is transferred to the unprinted surface of the sheet of paper T that has been reversed by the reverse paper feed path Lb.

A regulating member58is provided in the first branch part Q1. The regulating member58regulates a feed direction of the sheet of paper T, which is discharged from the fixing part9and fed from upstream to downstream of the third paper feed path L3, in a direction toward the discharging part50. The regulating member58regulates a feed direction of the sheet of paper T, which is fed from the discharging part50from downstream to upstream of the third paper feed path L3, to a direction toward the reverse paper feed path Lb.

A discharging part50is provided at an end part of the third paper feed path L3. The discharging part50is disposed in an upper part of the apparatus main body M. The discharging part50has an opening toward a left lateral face of the apparatus main body M (left side inFIG. 1). The discharging part50discharges the sheet of paper T outside the apparatus main body M. The discharging part50includes a pair of discharging rollers53. The pair of discharging rollers53discharges the sheet of paper T, which is fed in the third paper feed path L3from upstream to downstream, outside the apparatus main body M. The pair of discharging rollers53reverses the feed direction of the sheet of paper T at the discharging part50and feeds the sheet of paper T upstream of the third paper feed path L3.

A discharged paper collection part M1is provided on a side of the opening of the discharging part50. The discharged paper collection part M1is provided on an upper face (outer face) of the apparatus main body M. The discharged paper collection part M1is where the upper face of the apparatus main body M is recessed downward. A bottom face of the discharged paper collection part M1composes a portion of the upper face of the apparatus main body M. Sheets of paper T, on which predetermined toner images are formed and which are discharged from the discharging part50, are stacked and collected in the discharged paper collection part M1. It should be noted that a sensor (not illustrated) for detecting paper is disposed at a predetermined position of each paper feed path.

Next, operation of the printer1according to the first embodiment will be briefly described with reference toFIG. 1. First, single-side printing on a sheet of paper T housed in the paper feeding cassette52is described. The sheet of paper T contained in the paper feeding cassette52is fed to the first paper feed path L1by the forward feed roller61and the pair of paper feeding rollers81. The sheet of paper T is fed to the pair of resist rollers80by the pair of intermediate rollers82via the first junction P1and the first paper feed path L1.

The pair of resist rollers80performs skew compensation of the paper T and timing adjustment with respect to a toner image in the image forming unit GK.

The sheet of paper T discharged from the pair of resist rollers80is introduced between the intermediate image transfer belt7and the secondary image transfer roller8(the secondary image transfer nip N2) via the first paper feed path L1. A toner image is transferred to the sheet of paper T between the intermediate image transfer belt7and the secondary image transfer roller8.

Thereafter, the sheet of paper T is discharged from between the intermediate image transfer belt7and the secondary image transfer roller8, and introduced into the fixing nip between the heating rotator9aand the pressurizing rotator9bin the fixing part9. Toner is then fused in the fixing nip and fixed onto the sheet of paper T.

Subsequently, the sheet of paper T is fed to the discharging part50via the third paper feed path L3and discharged from the discharging part50to the discharged paper collection part M1by the pair of discharging rollers53. Single-side printing on the sheet of paper T contained in the paper feeding cassette is thus completed.

In a case of single-side printing on a sheet of paper T placed on the manual feeding tray65, the sheet of paper T is fed to the manual paper feed path La by the paper feeding roller66, and then fed to the pair of resist rollers80via the first junction P1and the first paper feed path L1. Subsequent operations are the same as single-side printing on a sheet of paper T contained in the paper feeding cassette52, and descriptions thereof are omitted.

Next, operation of the printer1performing duplex printing will be described.

In a case of single-side printing, as described above, printing is completed by discharging a sheet of paper T printed on one side from the paper discharging part50to the discharged paper collection part M1.

On the other hand, in a case of duplex printing, a sheet of paper T, one side of which has been printed, is reversed and re-fed to the pair of resist rollers80via the reverse paper feed path Lb.

In more detail, the operation is the same as the abovementioned single-side printing until a step prior to discharging of the sheet of paper T, one side of which has been printed, from the paper discharging part50by the pair of discharging rollers53. On the other hand, in a case of duplex printing, the pair of discharging rollers53stops rotating and resumes rotating in an opposite direction, while the sheet of paper T, one side of which has been printed, is held by the pair of discharging rollers53. When the pair of discharging rollers53rotates in the opposite direction, the sheet of paper T held by the pair of discharging rollers53is fed in an opposite direction (a direction from the paper discharging part50to the first junction Q1).

As described above, when a sheet of paper T is fed in the opposite direction in the third paper feed path L3, the sheet of paper T is guided to the reverse paper feed path Lb by the regulating member58, and enters the first paper feed path L1via the second junction P2. Here, the sheet of paper T is turned upside down from the position of one-side printing.

Furthermore, the pair of resist rollers80performs the abovementioned compensation or the abovementioned adjustment on the sheet of paper T, which is then introduced into the secondary image transfer nip N2via the first paper feed path L1. Since an unprinted surface of the sheet of paper T faces the intermediate image transfer belt7as a result of passing through the reverse paper feed path Lb, a toner image is transferred to the unprinted surface and duplex printing is realized on the sheet of paper T.

Next, the toner feeding device TS in the printer1of the first embodiment will be described in detail with reference toFIG. 2.FIG. 2is an external perspective view showing a toner feeding device TS viewed from a right front side to a left rear side of the apparatus main body M. An overview, a description of the specific structure of components, and a description of operations are given in this order for the toner feeding device TS.

First, the overview of the toner feeding device TS is given.

As shown inFIG. 2, the toner feeding device TS includes: toner cartridges5a,5b,5cand5das toner housing parts; an intermediate image transfer unit70that is connected to the drive mechanism100via a connecting member (not illustrated); developing units16a,16b,16cand16d; and the toner delivery devices500a,500b,500cand500d.

The intermediate image transfer unit70includes the intermediate image transfer belt7, the driven roller35(seeFIG. 1), the opposing roller18(seeFIG. 1), the tension roller36(seeFIG. 1), and a housing710. The housing710includes a pair of side plates711and a top plate712on which the toner cartridges5a,5b,5cand5dare placed. The pair of side plates711covers both side parts in a width direction (direction Y) of the intermediate image transfer belt7and rotatably supports the driven roller35, the opposing roller18and the tension roller36. The intermediate image transfer unit70is disposed between the toner cartridges5a,5b,5cand5ddisposed in parallel to each other in the horizontal direction (X direction) and the developing units16a,16b,16cand16ddisposed in parallel to each other in the horizontal direction (X direction) of the apparatus main body M in the vertical direction (Z direction).

Drive Mechanism

Next, the drive mechanism100in the printer1of the first embodiment will be described in detail with reference toFIGS. 3 to 7.FIG. 3is an external perspective view showing the drive mechanism100, which is attached to the toner feeding device TS.FIG. 4is an external perspective view showing the drive mechanism100shown inFIG. 3, viewed from a different direction.FIG. 5is a partial enlarged view showing the drive mechanism100shown inFIG. 3.FIG. 6is an exploded external perspective view showing the drive mechanism100shown inFIG. 3.FIG. 7is an exploded perspective view showing the drive mechanism100shown inFIG. 3, which is partially assembled.

As shown inFIG. 3, the drive mechanism100is disposed on a rear side of the intermediate image transfer unit70in the depth direction (Y direction). The drive mechanism100drives the intermediate image transfer unit70via the connecting member (not illustrated).

As shown inFIGS. 3 to 7, the drive mechanism100includes: a first resin cover110; a second resin cover210; a housing part300; a first sheet metal member310; a plurality of first rotation transmission wheels122composing a first rotation transmission wheel group120; a plurality of second rotation transmission wheels222composing a second rotation transmission wheel group220; a second sheet metal member320; a plurality of first positioning parts314as at least one positioning part; a plurality of first pin members128as a plurality of pin members; a belt revolution transmission wheel group330; and a plurality of belt supporting pin members336.

First Resin Cover, Second Resin Cover, Housing Part

As shown inFIGS. 5 to 7, the first resin cover110is formed in a box shape that is longer in the X direction and shorter in the Z direction. The first resin cover110has a first concave part112that is open toward one direction. The first resin cover110is a member made of resin.

The first resin cover110has: a base part111; a rib part (outer periphery)115that extends from an outer periphery of the base part111toward the second resin cover210in the Y direction; the first concave part112formed of the base part111and the rib part115; and a partitioning rib part115athat extends in the X direction so as to partition the first concave part112.

The first concave part112is provided on a side of a lateral face114, opening into the second resin cover210in the Y direction of the first resin cover110. The first concave part112is sized to house the plurality of first rotation transmission wheels122.

The second resin cover210is formed in a box shape that is longer in the X direction and shorter in the Z direction. The second resin cover210has a second concave part212that is open toward one direction. The second resin cover210is a member made of resin. The second resin cover210is disposed such that an outer periphery (a lateral face214) of the second concave part212faces and contacts an outer periphery (the lateral face114) of the first concave part112.

The second resin cover210has: a base part211; a rib part215that extends from an outer periphery of the base part211toward the first resin cover110in the direction Y; and a second concave part212formed of the base part211and the rib part215. The second concave part212is provided on a lateral face214, opening into a side of the first resin cover110in the Y direction of the second resin cover210. The second concave part212is sized to house the plurality of second rotation transmission wheels222.

As shown inFIG. 5, the housing part300is composed of the first concave part112and the second concave part212. The housing part300is composed of the first concave part112and the second concave part212that are arranged to be opposite to each other such that the lateral face114of the first resin cover110comes in contact with the lateral face214of the second resin cover210.

The housing part300has a first housing part301and a second housing part302. The housing part300is partitioned into the first housing part301and the second housing part302by the partitioning rib part115athat extends from a bottom face of the first concave part112of the first resin cover110in the Y direction.

The first housing part301houses the first sheet metal member310, the plurality of first rotation transmission wheels122(the first rotation transmission wheel group), and the plurality of second rotation transmission wheels222(the second rotation transmission wheel group), which will be described later. The second housing part302houses the plurality of belt revolution transmission wheels334(the belt revolution transmission wheel group), which will be described later.

First Sheet Metal Member and Second Sheet Metal Member

The first sheet metal member310is shape like a plate that is longer in the X direction and shorter in the Z direction. The first sheet metal member310is sized to be housed in the first concave part112. The first sheet metal member310is a metallic plate-like member. The first sheet metal member310is disposed in the housing part300such that a lateral face311thereof is directed to the first resin cover110and a lateral face312thereof is directed to the second resin cover210.

The plurality of through-hole shaped first positioning parts314, through which the plurality of first pin members128penetrates, is formed in the first sheet metal member310. The plurality of first positioning parts314is formed in the first sheet metal member310like a through hole. The first positioning parts314are penetrated through by the plurality of first pin members128and rotatably support the plurality of first rotation transmission wheels122.

The second sheet metal member320is layered on the lateral face113of the first resin cover110. The second sheet metal member320is not housed (not disposed) in the housing part300, but rather is disposed on an outer side of the drive mechanism100.

The second sheet metal member320is disposed on the lateral face113of the first resin cover110on a side opposite to the second resin cover210, such that the lateral face321of the second sheet metal member320faces the lateral face113of the first resin cover110. The second sheet metal member320is disposed opposite to the first sheet metal member310, interposing the first resin cover110therebetween. The first sheet metal member310is a metallic plate-like member.

The plurality of through-hole shaped second positioning parts324is formed in the second sheet metal member320. The plurality of first pin members128mates with the plurality of second positioning parts324, respectively. The plurality of first pin members128is installed upright on the second sheet metal member320, on a side directed to the first sheet metal member310. Each of the plurality of first pin members128is inserted into each of the plurality of first positioning parts314via the first resin cover110so as to be positioned.

Each of the plurality of first pin members128is inserted into a second positioning part324on the second sheet metal member320, a through hole117penetrating a bottom portion of the first concave part112of the first resin cover110, a rotational center of a first rotation transmission wheel122, and each of the plurality of first positioning parts314. In this manner, each of the plurality of first pin members128is positioned.

First Rotation Transmission Wheel Group and First Rotation Transmission Wheel

The first rotation transmission wheel group120is composed of the plurality of first rotation transmission wheels122. The plurality of first rotation transmission wheels122(the first rotation transmission wheel group120) is housed in the first housing part301of the housing part300. The plurality of first rotation transmission wheels122includes gears or the like.

The plurality of first rotation transmission wheels122is disposed so as to engage with each other, between the first concave part112of the first resin cover110and the lateral face311of the first sheet metal member210directed to a side of the first resin cover110. Each of the plurality of first pin members128is inserted into each of the at least one first rotation transmission wheel122. Each of the plurality of first rotation transmission wheels122is rotatably supported by each of the plurality of first pin members128.

Second Rotation Transmission Wheel Group and Second Rotation Transmission Wheel

The second rotation transmission wheel group220is composed of the plurality of second rotation transmission wheels222. The plurality of second rotation transmission wheels222(the second rotation transmission wheel group220) is housed in the second housing part302of the housing part300. The plurality of second rotation transmission wheels222includes gears or the like.

The plurality of second rotation transmission wheels222is disposed so as to engage with each other, between the second concave part212of the second resin cover210and the lateral face312of the second sheet metal member310directed to a side of the second resin cover210. Each of the plurality of second pin members129is inserted into each of the at lease one second rotation transmission wheel222. Each of the plurality of second rotation transmission wheels222is rotatably supported by each of the plurality of second pin members129.

The plurality of second pin members129is inserted upright into third positioning parts315shaped like a through hole formed in the first sheet metal member310. Each of the plurality of second pin members129is inserted into each of the at least one second rotation transmission wheel222. Each of the plurality of second pin members129rotatably supports the at least one second rotation transmission wheel222.

Belt Revolution Transmission Wheel Group

The drive mechanism100is provided with the belt revolution transmission wheel group330and the plurality of belt supporting pin members336. The belt revolution transmission wheel group330is housed in the second housing part302of the housing part300. The belt revolution transmission wheel group330has a continuous loop belt332and the plurality of belt revolution transmission wheels334on which the continuous loop belt332is wound.

The plurality of belt supporting pin members336is inserted into the plurality of belt revolution transmission wheels334and rotatably supports the plurality of belt revolution transmission wheels334. Each of the plurality of belt supporting pin members336is installed upright on the lateral face321of the second sheet metal member320, on a side directed to the first sheet metal member310. The plurality of belt supporting pin members336is inserted into the plurality of belt revolution transmission wheels334and rotatably supports the plurality of belt revolution transmission wheels334, respectively.

Grease Injection Hole

A grease injection hole G opens into the first housing part301via an injection bore326in the second sheet metal member320and an injection bore116in the first resin cover110. The grease injection hole G is an opening that is formed to cause the outside of the drive mechanism100and the first housing part301to communicate with each other. A user injects grease, which is necessary for the first rotation transmission wheels122composing the first rotation transmission wheel group120and the like, from outside the drive mechanism100to inside the first housing part301through the grease injection hole G.

Assembly of Drive Mechanism

As shown inFIGS. 5 to 7, the drive mechanism100is assembled as follows.

First, an operator installs the plurality of first pin members128upright in the second positioning parts324, such that the plurality of first pin members128extends toward the lateral face321of the second sheet metal member320. Since each of the plurality of first pin members128is installed upright on the second sheet metal member320, it is possible to maintain the accuracy of the interaxial distance between adjacent first pin members128.

Next, the operator inserts the plurality of first pin members128respectively into a plurality of through holes117formed in the first resin cover110. As a result, the lateral face321of the second sheet metal member320closely contacts the lateral face114of the first resin coyer110. In addition, the plurality of first pin members128is disposed inside the first concave part112of the first resin cover110. Since the plurality of first pin members128is installed upright on the second sheet metal member320as described above, the interaxial distance between adjacent first pin members128is still maintained with high accuracy.

Next, as shown inFIG. 5, the operator inserts the plurality of first pin members128rotatably into the plurality of first rotation transmission wheels122, respectively. A first rotation transmission wheel122is fitted onto a first pin member128while the first rotation transmission wheel122is sliding in the Y direction, in which the rotational axis thereof extends. Here, the operator makes adjacent first rotation transmission wheels122slide in the Y direction while slightly rotating them in the rotational direction thereof, such that the adjacent first rotation transmission wheels122engage with each other.

Next, as shown inFIG. 7, the operator disposes the first sheet metal member310to be layered on the first resin cover110. Here, the operator inserts a head part of the first pin member128, which is exposed from the first rotation transmission wheel122, into a first positioning part314, which is a through hole in the first sheet metal member310. During the steps described above, the accuracy of the interaxial distance between the adjacent first pin members128is maintained, while the accuracy of the interaxial distance between the first positioning parts314on the first sheet metal member310is also maintained. Accordingly, it is possible for the operator to insert the head part of the first pin member128into the first positioning part314, which is a through hole in the first sheet metal member310.

In the following description of assembly steps (including post-assembly), both ends of the plurality of first pin members128are inserted into the first positioning parts314on the first sheet metal member310and the second positioning parts324on the second sheet metal member320. Accordingly, the interaxial distance between the adjacent first pin members128is maintained with high accuracy.

Next, as shown inFIG. 7, the operator inserts the plurality of second pin members129into the through-hole shaped third positioning parts315formed in the first sheet metal member310. Since the plurality of second pin members129is installed upright on the first sheet metal member310, the interaxial distance between adjacent second pin members129is maintained with high accuracy.

The operator places the second rotation transmission wheels222on the second pin members129that have been installed upright. Since the interaxial distance between the adjacent second pin members129is maintained with high accuracy, it is possible to cause the plurality of second rotation transmission wheels222to engage with each other with high accuracy. Since the plurality of second pin members129is inserted into the plurality of second rotation transmission wheels222, respectively, the plurality of second pin members129rotatably supports the plurality of second rotation transmission wheels222.

Next, as shown inFIGS. 3 and 5, the operator attaches the second resin cover210to the first resin cover110. As a result, the first concave part112and the second concave part212form into the housing part300(the first housing part301and the second housing part302). In addition, the first housing part301houses the first sheet metal member310, the first rotation transmission wheel group120, and the second rotation transmission wheel group220. The second housing part302houses the belt revolution transmission wheel group330.

Grease Injection

A user injects grease, which is necessary for the first rotation transmission wheels122composing the first rotation transmission wheel group120and the like, from outside the drive mechanism100to inside the first housing part301through the grease injection hole G.

The present embodiment provides the following effects, for example.

Since both ends of the plurality of first pin members128are inserted into the first positioning parts314on the first sheet metal member310and the second positioning parts324on the second sheet metal member320according to the present embodiment, the interaxial distance between the adjacent first pin members128is maintained with high accuracy. As a result, noise due to engagement of gears hardly occurs upon rotation of the first rotation transmission wheels122and the second rotation transmission wheels222.

In the present embodiment, the first rotation transmission wheel group120and the second rotation transmission wheel group220are housed in the housing part300separately from the belt revolution transmission wheel group330, by means of the partitioning rib part115a. Therefore, according to the present embodiment, the grease and the like injected to the first rotation transmission wheels122of the first rotation transmission wheel group120does not easily adhere to the belt revolution transmission wheel group330.

In the present embodiment, since the first rotation transmission wheel group120and the second rotation transmission wheel group220are housed in the first housing part301, the noise due to engagement of gears upon rotation of the first rotation transmission wheels122and the second rotation transmission wheels222is hardly transmitted from inside to outside the first housing part301.

Although a preferred embodiment of the present invention has been described above, the present invention is not limited thereto and can be carried out using various modes.

The image forming apparatus of the present invention is not particularly limited, and may include a copy machine, a printer, a facsimile machine, or a multi-functional printer having functions thereof.