Patent Grant
8165511
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-080667 filed on Mar. 27, 2009.
The present invention relates to an offset correcting device, an intermediate transferring device, a transferring device, and an image forming apparatus.
According to an aspect of the invention, there is provided an offset correcting device including: an endless belt-like member having an endless belt-like shape; a rotation supporting member which has a rotation shaft in which an axial direction extends along a width direction of the endless belt-like member, and which is rotated while supporting the endless belt-like member; an interlocking member which is supported by one end portion of the rotation shaft to be movable along the axial direction, and which can be contacted with a width direction edge of the endless belt-like member; and a shaft displacing member which has: a swing center that is placed at a position deviated from the rotation shaft, and that intersects with the axial direction; a rotation shaft contacting portion which is contacted with the one end portion of the rotation shaft of the rotation supporting member; and an interlocking member contacting portion which is contacted with the interlocking member, which is movable integrally with the rotation shaft contacting portion, and in which, when the interlocking member is pressed against the width direction edge of the endless belt-like member that is moved to one end side of the rotation shaft, the interlocking member contacting portion and the rotation shaft contacting portion are swung about the swing center, and the rotation shaft contacting portion tilts the rotation shaft in a tilting direction coincident with a direction along which the endless belt-like member is moved toward another end of the rotation shaft.
Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:
θ . . . increment angle, θ0 . . . angle formed by width direction line and shaft displacement line segment, 9 . . . center mounting portion, 9a . . . inner circumferential face, 9b . . . cutout insertion portion, 12, 12 . . . frame mounting portion, 26 . . . interlocking member, 27 . . . shaft displacing member, 27a . . . swing center, 27a1, 27a2 . . . cutout face, 27e . . . rotation shaft contacting portion, plate-like member, convex arcuate face, (27f+27g) . . . interlocking member contacting portion, 27h . . . contacting face, AR1 . . . movement range of interlocking member contacting portion, AR2 . . . swing range of swing center, B . . . endless belt-like member, BM . . . offset correcting device, F . . . fixing device, Fb . . . second frame, Ft, Ft′ . . . first frame, Gy to Gk . . . developing device, L . . . length of shaft displacement line segment, L1 . . . opening width, L2 . . . cutout distance, Lx . . . moving distance of endless belt-like member in width direction, Ly . . . moving distance of rotation shaft in tilting direction, P0 . . . pre-movement contacting portion contact position, Pmax . . . maximum post-movement contacting portion contact position, Py to Pk . . . image carrier, r0 . . . shaft displacement line segment, r1 . . . diameter of column, Rj . . . rotation supporting member, Rja . . . rotation shaft, S . . . medium, x0 . . . width direction line, U . . . image forming apparatus.
Next, examples which are specific examples (hereinafter, referred to as examples) of an exemplary embodiment of the invention will be described with reference to the drawings. However, the invention is not restricted to the following examples.
In order to facilitate the understanding of the following description, the front and rear directions in the drawings are indicated as X-axis directions, the right and left directions are indicated as Y-axis directions, and the upper and lower directions are indicated as Z-axis directions. The directions or sides indicated by the arrows X, −X, Y, −Y, Z, and −Z are the front, rear, right, left, upper, and lower directions, or the front, rear, right, left, upper, and lower sides, respectively.
In the figures, the symbol in which “●” is written in “◯” indicates the arrow which is directed from the rear of the sheet to the front, and that in which “x” is written in “◯” indicates the arrow which is directed from the front of the sheet to the rear.
In the following description with reference to the drawings, illustrations of members other than those which are necessary in description are suitably omitted for the sake of easy understanding.
Referring to
Referring to
The printer U has a controller C which performs various controls on the printer U, an image processing portion GS in which the operation is controlled by the controller C, an image writing device driving circuit DL, a power supplying device E, and the like. The power supplying device E applies voltages to charging rollers CRy to CRk which are an example of a charging device that will be described later, developing rollers G1y to G1k which are an example of a developer holding member, transferring rollers T1y to T1k which are an example of a transferring device, etc.
The image processing portion GS converts print information supplied from an external image information transmitting apparatus or the like, to image information for forming latent images corresponding to four color images of K: black, Y: yellow, M: magenta, and C: cyan, and outputs the image information to the image writing device driving circuit DL at a predetermined timing. The image writing device driving circuit DL outputs a driving signal to a latent image writing device ROS in accordance with the supplied image information for the respective colors. The latent image writing device ROS emits laser beams Ly, Lm, Lc, Lk which are an example of image writing light for writing color images, in accordance with the driving signal.
Referring to
Referring to
The developer container V has stirring and conveying chambers V1, V2 in which the developer to be supplied to the developing roll G1k is conveyed while being stirred. Circulating and conveying R1, R2 which circularly convey the developer are placed in the stirring and conveying chambers V1, V2. A developer replenishing path H1 through which the developer is replenished is connected to the left stirring and conveying chamber V2, and a first developer replenishing chamber H2 which houses the developer for replenishment is connected to the developer replenishing path H1. The first developer replenishing chamber H2 is connected to a second developer replenishing chamber H4 which is above placed, through a developer replenishment connecting path H3. Replenishing developer carrying members R3, R4, R5, R6, R7 which convey the developer toward the stirring and conveying chambers V1, V2 are placed in the developer replenishing path H1, the first developer replenishing chamber H2, the developer replenishment connecting path H3, and the second developer replenishing chamber H4, respectively. The members denoted by the reference numerals H1 to H4 and R3 to R7 constitute developer replenishment containers H1 to H4+R3 to R7 in Example 1.
In the photosensitive member Pk, after the surface is uniformly charged by the charging roll CRk in a charging region Q1k opposed to the charging roll CRk, a latent image is written by the laser beam Lk in a latent image forming region Q2k. The written electrostatic latent image is visualized in a developing region Qgk opposed to the developing device Gk.
The visible image forming device UK for black in Example 1 is configured by a detachable body, or a so-called process cartridge UK to which the photosensitive member Pk, the charging device CRk, the developing device Gk, the discharging member Jk, the photosensitive member cleaner CLk, the developer replenishment containers H1 to H4+R3 to R7, and the like are detachably attached in an integral manner. The visible image forming device is configured so as to be attachable to and detachable from the image forming apparatus main unit U1 in a state where the opening/closing portion U2 is moved to the open position.
In the same manner as the visible image forming device UK for black, the visible image forming devices UY, UM, UC for the other colors are configured by detachable bodies which attachable to and detachable from the image forming apparatus main unit U1, or so-called process cartridges UY, UM, UC. In the printer U of Example 1, the process cartridges UY to UK are arranged in the upper and lower directions.
Referring to
An image density sensor SN1 for detecting the density of an image which is formed at a predetermined timing by an image density adjusting unit (not shown) of the controller C, i.e., a so-called patch image is placed on the downstream side in the medium conveying direction of the medium conveying belt B, i.e., on the upper side. On the basis of the image density detected by the image density sensor SN1, the image density adjusting unit of the controller C adjusts the voltages to be applied to charging rollers CRy to CRk, the developing devices Gy to Gk, and the transferring rolls T1y to T1k, and the intensities of the latent image writing light beams Ly to Lk, thereby performing adjustment and correction of the image density, or a so-called process control.
A belt cleaner CLb which is an example a conveying member cleaner is placed on the downstream side of the image density sensor SN1 in the medium conveying direction of the medium conveying belt B.
The recording sheet S in the sheet feed container TR1 which is placed below the medium conveying belt B is picked up by a pickup roll Rp which is an example of a medium picking up member, separated one by one by separating rolls Rs which are an example of a medium separating member, and then conveyed to a recording medium conveying path SH configured by a sheet guide SG which is an example of a guiding member.
The recording sheet S in the recording medium conveying path SH is sent to registration rolls Rr which are an example of a feeding means, and which adjust the timing of feeding the sheet to the medium conveying belt B. The registration rolls Rr feed the recording sheet S at a predetermined timing to a recording medium attracting position Q6 which is a region opposed to the driven roll Rj. The recording sheet S conveyed to the recording medium attracting position Q6 is electrostatically attracted to the medium conveying belt B. In the belt module BM in Example 1, a guiding member for guiding the recording sheet S is omitted between the registration rolls Rr and the medium conveying belt B.
The recording sheet S attracted to the medium conveying belt B is gradually passed through transferring regions Q3y, Q3m, Q3c, Q3k where the sheet is contacted with the photosensitive members Py to Pk.
In the transferring regions Q3y to Q3k, a transfer voltage the polarity of which is opposite to the charge polarity of the toner is applied from the power supplying device E controlled by the controller C to the transferring rolls T1y to T1k which are placed on the rear face side of the medium conveying belt B.
In the case of a multi-color image, the toner images on the photosensitive members Py to Pk are overlappingly transferred onto the recording sheet S on the medium conveying belt B by the transferring rolls T1y to T1k. In the case of a so-called monochromatic image, only a black toner image is formed on the photosensitive member Pk, and only the toner image of K: black is transferred to the recording sheet S by the transferring device T1k.
After the transfer of the toner image, the photosensitive members Py to Pk are discharged by the discharging members Jy to Jk in discharging regions Qjy to Qjk, and then cleaned by recovering toners remaining on the surfaces by the photosensitive member cleaners CLy to CLk in cleaning regions Q4y to Q4k. The photosensitive members are again charged by the charging rollers CRy to CRk.
The recording sheet S onto which the toner images are transferred undergoes fixation in a fixing region Q5 where a heating roll Fh which is an example of a heating and fixing member of a fixing device F, and a pressurizing roll Fp which is an example of a pressurizing and fixing member are pressingly contacted each other. The recording sheet S onto which the images are fixed is guided by a guiding roller Rgk which is an example of a discharge guiding member, and then discharged from discharging rollers Rh which are an example of a medium discharging member, to a medium discharging portion TRh.
After the recording sheet S is separated from the medium conveying belt B, the medium conveying belt is cleaned by the belt cleaner CLb.
Referring to
Referring to
Referring to
In the front and rear belt support plates Fb1, Fb2, the driven roll Rj is rotatably supported below the long holes 12. In the driven roll Rj, a driven shaft Rja in which the axial direction extends in the front and rear directions coincident with the width direction of the medium conveying belt B, and which is an example of a rotation shaft is supported by a driven shaft supporting member 13 which is shown in
Referring to
Referring to
Referring to
Referring to
Lower portions of the front and rear transferring roll support frames Ft1, Ft2 are coupled to each other by a plate coupling member Ft3 which is an example of a transferring member supporting member coupling member. Both end portions of the plate coupling member Ft3 are passed through the long holes 12, 12 of the front and rear belt support plates Fb1, Fb2 to be projected to the outside of the outer frame members Fb. Therefore, the plate coupling member Ft3 is supported movably along the long holes 12, 12.
A swing bracket SB which is an example of a movable frame is supported by a front end portion of the plate coupling member Ft3, so as to be swingable about the plate coupling member Ft3.
In Example 1, a through hole SB1 through which the plate coupling member Ft3 are passed to be supported is formed in an upper end portion of the swing bracket SB. A spring supporting groove SB2 which is a vertically extending groove, and which is an example of an elastic member supporting portion. A slider SB3 which is movable along the spring supporting groove SB2, and which is an example of a stretch movable member is supported by the swing bracket SB, and the front bearing 13a is supported by the slider SB3. A stretch spring SPa which is an example of an elastic member, and which is an example of a tension applying member is mounted between the slider SB3 and an upper end portion of the spring supporting groove SB2.
Therefore, the front bearing 13a is coupled to the plate coupling member Ft3 through the swing bracket SB, and, interlockingly with the swing bracket SB, supported rotatably about the plate coupling member Ft3.
The rear transferring roll support frame Ft2 is formed to be downward extended so as to be longer than the front transferring roll support frame Ft1. In Example 1, the lower end portion of the rear transferring roll support frame Ft2 has a spring supporting groove Ft2a similar to the spring supporting groove SB2, and a slider Ft2b which supports the rear bearing 13b, correspondingly with the slider SB3. Similarly with the swing bracket SB, a stretch spring SPa is mounted between the slider Ft2b and an upper end portion of the spring supporting groove Ft2a.
Therefore, the rear bearing 13b is supported so as to be vertically movable by the rear transferring roll support frame Ft2 through the slider Ft2b.
The bearings 13a, 13b are downward urged by the stretch springs SPa, Spa. Namely, the driven roll Rj is supported while being pressed in the downward direction which is an example of the downstream side in the stretching direction, so as to stretch the medium conveying belt B, and also functions as a stretching member which stretches over the medium conveying belt B.
A bracket press spring SPb which is an example of a tilt urging member is supported by the plate coupling member Ft3. One end of the spring is supported by the front transferring roll support frame Ft1, and the other end is supported by the swing bracket SB. Namely, the swing bracket SB in Example 1 is urged by the bracket press spring SPb toward a front end portion of the lower tie bar Fb4 which is placed on the right side. In Example 1, as a result, the front end portion of the driven shaft Rja of the driven roll Rj is preset so as to be tilted in the right direction with respect to the rear end portion.
The driving shaft Rda of the driving roll Rd in Example 1 is placed in parallel to the front and rear directions. In Example 1, therefore, the medium conveying belt B is preset so as to be offset in the front direction.
In the front and rear transferring roll support frames Ft1, Ft2, shaft position adjustment long holes Fty, Ftm, Ftc, Ftk which extend in the right and left directions are formed respectively correspondingly with the positions of the transferring rollers T1y to T1k. Referring to
Referring to
As shown in
Referring to
In Example 1, the pressing forces exerted by the transferring shaft urging springs 23y to 23k are set to be larger than those exerted by the elastic springs 21b. The force by which the medium conveying belt B is pressed by the elastic springs 21b is preset to a level which is slightly larger than the tension of the medium conveying belt B, and at which the belt pressing pins 20 are contacted with the medium conveying belt B and do not substantially deform the shape of the medium conveying belt B.
Referring to
When the eccentric cam HC is moved to a belt-like member contacting position shown in
Referring to
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As shown in
Columnar extension portions 27b, 27b which extend in parallel to the cutout faces 27a1, 27a2 are formed on the both end portions of the swing center 27a in the upper and lower directions coincident with the center axis direction. Semi-circular contacting portions 27c having a D-like section shape which vertically extends are formed on end portions of the extension portions 27b, 27b which are opposite to the swing center 27a. In the contacting portions 27c in Example 1, a recess 27d which is configured by an opening that is recessedly cut is formed in the vertical middle of opposite outer end portions of the extension portions 27b, 27b. In the recess 27d in Example 1, a shaft contacting face 27e which is configured by a convex curved body that vertically extends, which is to be contacted with the driven shaft Rja, and which is an example of a rotation shaft contacting portion is formed.
Upper and lower contacting portions 27f, 27g which are bifurcated across the recess 27d, and which are examples of upstream and downstream contacting portions are formed on the sides of the upper and lower ends of the recess 27d. The left end faces 27h which are contacting faces of the contacting portions 27f, 27g are contacted with the belt offset sensing member 26 on the vertical sides across the driven shaft Rja.
The upper and lower contacting portions 27f, 27g constitute the interlocking member contacting portion (27f+27g) in Example 1.
Referring to
The outer frame members Fb, the transfer frame Ft, the transfer frame pressing spring SPc, the eccentric cam HC, and the like constitute a belt moving mechanism Fb+Ft+SPc+Hc which is an example of a belt-like member moving mechanism in Example 1. The outer frame members Fb, the belt supporting roll Rd+Rj, the medium conveying belt B, the transfer frame Ft, the transferring rolls T1y to T1k, the recovering device KS, the belt offset sensing member 26, the shaft displacing member 27, and the like constitute the belt module BM in Example 1.
In the thus configured printer U which is an example of the image forming apparatus of Example 1, when an image forming operation, or a so-called job is started, the recording sheet S is held on the surface of the medium conveying belt B, images are transferred to the recording sheet S when the recording sheet is passed through the transferring regions Q3y to Q3k, and the images are fixed in the fixing region Q5 of the fixing device F.
When the medium conveying belt B meanders, a problem occurs in the conveyance of the recording sheet S. In Example 1, as shown in
Therefore, the interlocking member contacting portion (27f+27g) with which the belt offset sensing member 26 is contacted is forward pressed, and the pressed interlocking member contacting portion (27f+27g) of the shaft displacing member 27 is swung about the swing center 27a. In this case, the shaft contacting face 27e of the shaft displacing member 27 is swung integrally with the interlocking member contacting portion (27f+27g) to press the driven shaft Rja in the left direction.
Therefore, the medium conveying belt B is moved in the rear direction, the front end of the driven shaft Rja approaches being parallel to the rear end, or is tilted in the rear direction, so that the medium conveying belt B is held at the balanced position where the offset of the medium conveying belt B stops and the belt balances. Therefore, offset of the medium conveying belt B is restricted, and offset of the medium conveying belt B is eliminated. In the printer U of Example 1, in accordance with movements of the members B, 26 in the front direction, the shaft displacing member 27 is swung on the XY plane including the X direction as the front and rear directions, and the Y direction as the right and left directions, and the driven shaft Rja is moved in the left direction.
In the printer U of Example 1, in accordance with offset of the members B, 26, the shaft displacing member 27 is swung about the swing center 27a to tilt the driven shaft Rja. The structure for correcting meandering of the medium conveying belt B is simplified as compared with the technique in which the pressing force of the belt offset sensing member is measured and the driven shaft is tilted, and the technique in which the rotation torque of the medium conveying belt is given to the belt offset sensing member and the string member is wound, thereby tilting the driven shaft.
In the printer U of Example 1, the locus of rotation of the shaft displacing member 27 exhibits a two-dimensional circular shape. Therefore, the structure for correcting meandering of the medium conveying belt B is simplified as compared with the technique in which the locus of rotation of the shaft displacing member exhibits a three-dimensional bevel shape.
In the printer U of Example 1, the radius of curvature of the left end faces 27h is set so that the contact profile PF shown in
Lx=L(cos(θ0)−cos(θ0+θ)) (1-1)
Ly=L(sin(θ0+θ)−sin(θ0)) (1-2)
In the printer U of Example 1, therefore, the relationships between the moving distances Lx, Ly can be adjusted on the basis of trigonometric functions of the angles θ0, θ of the shaft displacing member 27 as shown in Expressions (1-1) and (1-2) above.
In the printer U of Example 1, as compared with the case where the moving distances Lx, Ly cannot be adjusted on the basis of Expressions (1-1) and (1-2) above, consequently, the moving distance Lx [mm] of the members B, 26 can be efficiently converted to the moving distance Ly [mm] of the driven shaft Rja by swing of the shaft displacing member 27.
In the printer U of Example 1, the relationships between the moving distance Lx [mm] of the members B, 26 and the moving distance Ly [mm] of the driven shaft Rja can be adjusted on the basis of the radius of curvature of the left end faces 27h which are contact faces with respect to the belt offset sensing member 26.
In the printer U of Example 1, as compared with the case where the moving distances Lx, Ly cannot be adjusted on the basis of Expressions (1-1) and (1-2) above, the movement of the members B, 26, and the swing of the shaft displacing member 27 can be smoothly interlocked with each other. In the printer U of Example 1, even when the balanced position in the case where the multi-color image forming operation shown in
In the printer U of Example 1, as compared with the configuration where the radius of curvature of the left end faces 27h is not smoothly continuously changed, the noise level when meandering of the medium conveying belt B is corrected is lowered.
The printer U of Example 1 is configured so that the driven shaft Rja which is formed into a columnar shape extending in the front and rear directions, and the shaft contacting face 27e configured by a convex curved body which extends in the upper and lower directions make a point contact with each other. In the printer U of Example 1, as compared with the configuration where the driven shaft Rja and the shaft contacting face 27e do not make a point contact with each other, therefore, the noise level when meandering of the medium conveying belt B is corrected is lowered, and wear between the driven shaft Rja and the shaft contacting face 27e is reduced, so that the maintenance cost of the shaft displacing member 27 can be reduced.
In the thus configured printer U of Example 1, as shown in
As a result, in the printer U of Example 1, as compared with the configuration where the driven shaft Rja and the shaft displacing member 27 are supported by the same frame, the shaft displacing member 27 can be easily mounted on the belt module BM. In the printer U of Example 1, as compared with the configuration where the driven shaft Rja and the shaft displacing member 27 are supported by the same frame, particularly, a wide region such as a space where the portions 27a to 27e of the shaft displacing member 27 can be placed can be ensured, and the degree of freedom of placement of the swing center 27a can be enhanced.
In the thus configured printer U of Example 1, as shown in
The cutout insertion portion 9b is formed on the left side or outside of a swing range AR2 of the swing center 27a corresponding to the movement range AR1. In the printer U of Example 1, during swing of the swing center 27a in which the shaft displacing member 27 swings in the swing range AR2, therefore, the swing center 27a is prevented from dropping off from the inner circumferential face 9a. In the printer U of Example 1, as compared with the case where the cutout insertion portion 9b is placed in the swing range AR2, and a drop-off preventing member for the swing center 27a closing the opening of the cutout insertion portion 9b is used, the swing center 27a can be easily mounted, and the number of components of the supporting member for supporting the swing center 27a can be reduced.
In the thus configured printer U of Example 1, the medium conveying belt B extends in the upper and lower directions coincident with the stretching direction of the stretching rolls Rd, Rj. As shown in
In the printer U of Example 1, as shown in
In the printer U of Example 1, a winding angle that is an angle by which the medium conveying belt B is wound around the driven roll Rj is set to be about 180°. Therefore, Example 1 is set so that, when the medium conveying belt B is forward offset, the front end edge of the medium conveying belt B presses right, lower, and left end portions of the belt offset sensing member 26 in a U-like manner.
Therefore, the interlocking member contacting portion (27f+27g) in Example 1 is contacted with two places across the driven shaft Rja, or the lateral middle portions which are the middles of the right and left end portions of the belt offset sensing member 26 that are pressed by the medium conveying belt B. In an assumed case where the interlocking member contacting portion (27f+27g) is contacted with only one place of the belt offset sensing member 26, for example, only the upper contacting portion contact position P1, consequently, there is the possibility that the belt offset sensing member 26 pressed by the medium conveying belt B is swung and tilted while using the upper contacting portion contact position P1 as a fulcrum. In this case, the tilted belt offset sensing member 26 is hardly moved in the axial direction, and there is the possibility that offset of the medium conveying belt B is hardly interlocked with the belt offset sensing member 26. Therefore, correction of offset may be delayed, or the accuracy may be impaired.
By contrast, in the printer U of Example 1, the contact position of the interlocking member contacting portion (27f+27g) is placed in two places across the driven shaft Rja. AS compared with the case where the contact position of the interlocking member contacting portion (27f+27g) is placed in one place, therefore, offset of the medium conveying belt B can be efficiently transmitted to interlocking of the belt offset sensing member 26, and swing of the shaft displacing member 27.
When the winding angle is smaller than 180°, the range where the medium conveying belt B is contacted with the belt offset sensing member 26 tends to be concentrated to one portion, and the belt offset sensing member 26 is easily tilted. When, as in the interlocking member contacting portion (27f+27g) in Example 1, the contact is made in two places across the driven shaft Rja, the effect of reducing the tilting of the belt offset sensing member 26 is increased. Therefore, the belt offset sensing member 26 is easily interlocked with offset of the medium conveying belt B, and the responsibility of the offset correction by the shaft displacing member 27 is improved.
In the printer U of Example 1, the winding angle that is an angle by which the medium conveying belt B is wound around the driven roll Rj is set to be about 180°. Therefore, Example 1 is set so that, when the medium conveying belt B is forward offset, the front end edge of the medium conveying belt B presses right, lower, and left end portions of the belt offset sensing member 26 in a U-like manner.
As a result, in the printer U of Example 1, as compared with the case where the winding angle is smaller than 180°, the range where the belt offset sensing member 26 is contacted with the front edge of the medium conveying belt B is widened, and the member is easily moved in the front direction in an interlocking manner. Namely, the belt offset sensing member 26 can easily sense forward offset of the medium conveying belt B. In the printer U of Example 1, as compared with the case where the winding angle is smaller than 180°, therefore, offset of the medium conveying belt B can be efficiently transmitted to interlocking of the belt offset sensing member 26, and swing of the shaft displacing member 27.
In the printer U of Example 1, therefore, the belt offset sensing member 26 can be efficiently and smoothly moved interlockingly with offset of the medium conveying belt B. Even in the case where the rigidity of the medium conveying belt B is low, consequently, meandering of the medium conveying belt B can be corrected without causing wrinkles in the front edge of the medium conveying belt B which is contacted with the belt offset sensing member 26. As a result, in the printer U of Example 1, the production cost of the medium conveying belt B can be reduced.
Next, Example 2 of the invention will be described. In the description of Example 2, components corresponding to those of Example 1 described above are denoted by the same reference numerals, and their detailed description is omitted.
Example 2 is different from Example 1 in the following points, but configured in a similar manner as Example 1 in the other points.
Referring to
Referring to
In the swing restricting portion 31, plate-like left and right end walls 31b, 31c which forward extend from the left and right ends of the rear end wall 31a. A corner portion 31d formed by the rear end wall 31a and the right end wall 31c constitutes the swing restricting portion 31 in Example 2. On the side of the right end wall 31c in the right direction which is an example of a perpendicular direction, a center supporting recess 32 having a recessed shape which is formed by outward recessing the inner surface of the front transferring roll support frame Ft1 is formed.
A plate-like front end wall 32a which rightward extends from the front end of the right end wall 31c is formed in the center supporting recess 32 in Example 2. A projection 32b which is forward projected is formed in a right end portion of the outer surface of the front end wall 32a in Example 2. In Example 2, in place of the bracket press spring SPb in Example 1, a driven-shaft press spring SPb′ which is an example of a tilt urging member is connected between the projection 32b and the driven shaft Rja.
In Example 2, therefore, the swing bracket SB is urged toward the right end wall 31c through the driven shaft Rja and the front bearing 13a, by the driven-shaft press spring SPb′. As a result, in Example 2, similarly with Example 1, the front end portion of the driven shaft Rja is preset so as to be tilted in the right direction with respect to the rear end portion.
In Example 2, similarly with Example 1, the driving shaft Rda of the driving roll Rd is placed in parallel to the front and rear directions, and, therefore, the medium conveying belt B is preset so as to be offset in the front direction.
An inner wall 32c which extends in the upper and lower directions is formed in a middle portion in the right and left directions of the inner surface of the front end wall 32a. In Example 2, in place of the groove portion 9 of the lower tie bar Fb4 in Example 1, a center supporting portion 32c1 which is a corner portion formed by the front end wall 32a and a left end portion of the inner wall 32c is formed. In Example 2, in place of the shaft displacing member 27 in Example 1, a shaft displacing member 27′ is supported by the center supporting portion 32c1. Namely, the shaft displacing member 27′ in Example 2 is swingably supported in a state where the position of the swing center 27a in the front and rear directions partly overlaps that of the front bearing 13a in the front and rear directions.
In the shaft displacing member 27 in Example 1, the shaft displacement line segment r0 shown in
As indicated by the alternate long and short dash line in
In the thus configured printer U which is an example of the image forming apparatus of Example 2, as shown in
As a result, in the printer U of Example 2, the whole length of the driven shaft Rja can be shortened, and the whole belt module BM and the whole printer U can be miniaturized.
In the case where the front end portion of the driven shaft Rja is lifted while using the rear bearing 13b of the driven shaft Rja as a fulcrum, the front end portion can be lifted because of the principle of leverage by a smaller force when a position which is remote from the rear bearing 13b as far as possible, i.e., a position which is close to the front bearing 13a as far as possible is used as a force application point. Namely, when the shaft contacting face 27e of the shaft displacing member 27 which functions as the force application point is placed at a position which is close to the front bearing 13a, the front end portion can be lifted by a smaller force.
In Example 2, the swing center 27a is placed overlappingly with the axial position of the front bearing 13a, and the shaft contacting face 27e is placed axially outside of the driven shaft Rja as far as possible. In the printer U of Example 2, as compared with the case where the swing center 27a is not overlappingly placed with respect to the axial position of the front bearing 13a, therefore, the shaft contacting face 27e can be placed at a position which is close to the front bearing 13a, and the driven shaft Rja can be tilted by a small force.
As shown in
In the printer U of Example 2, as compared with the case where the range from the swing center 27a to the outer end portion of the contacting portions 27c is linearly formed, the shaft contacting face 27e is placed at a position which is close to the front bearing 13a, the driven shaft Rja can be lifted by a further small force.
In Example 2, the radius of curvature of the left end faces 27h becomes larger as further advancing from the outer end side of the recess 27d toward the extension portions 27b, 27b, and is set so that the contact profile PF′ shown in
Therefore, Example 2 is set so that, in the case where the medium conveying belt B is offset, as the front end portion of the driven shaft Rja is further moved in the left direction in which offset is corrected, to approach the balanced position where offset of the medium conveying belt B stops, the moving distance of the driven shaft Rja is more reduced. As a result, in the printer U of Example 2, as compared with the case where the radius of curvature of the left end faces 27h is not set so that the contact profile PF′ exhibits an involute curve, offset of the medium conveying belt B is easily converged in the vicinity of the balanced position.
In the thus configured printer U of Example 2, the corner portion 31d formed by the rear end wall 31a of the swing restricting portion 31 and the right end wall 31c is placed on the left side of the shaft displacing member 27′. In the case where, when offset of the medium conveying belt B is corrected in the front direction, the shaft displacing member 27′ is swung, therefore, the swing of the shaft displacing member 27′ is restricted at the maximum swing position where the shaft displacing member 27′ is contacted with the corner portion 31d.
In the printer U of Example 2, therefore, the swing range of the shaft displacing member 27′ can be restricted by the corner portion 31d. When offset of the medium conveying belt B is corrected, for example, the shaft displacing member 27′ can be prevented from being swung to a non-functional region where the shaft displacing member 27′ exceeds the so-called top dead point and cannot return with following returning of the medium conveying belt B and the driven shaft Rja.
In the printer U of Example 2, the maximum swing position can be set at an arbitrary position by adjusting the position of the corner portion 31d, and the shaft displacing member 27′ can be restricted from being excessively swung.
In other points, the printer U of Example 2 can attain the same effects as the printer U of Example 1.
Next, Example 3 of the invention will be described. In the description of Example 3, components corresponding to those of Example 2 described above are denoted by the same reference numerals, and their detailed description is omitted.
Example 3 is different from Example 2 in the following points, but configured in a similar manner as Example 2 in the other points.
Referring to
The upper end wall 32d and the lower end wall 32e constitute a movement restricting portion (32d+32e) in Example 3.
Example 3 is preset so that the length L3 between the upper end wall 32d and the lower end wall 32e, i.e., the length L3 of the center supporting recess 32 in the upper and lower directions is longer than the length L4 of the shaft displacing member 27′ in the upper and lower directions in which the swing center 27a extends. Namely, the width of the center supporting recess 32 in the upper and lower directions is formed to be larger than that of the shaft displacing member 27′ in the upper and lower directions.
As a result, a center supporting portion 32c1′ which is a corner portion formed by the front end wall 32a in Example 3 and the inner wall 32c is set so that the length in the upper and lower directions is longer than that of the center supporting portion 32c1 in Example 2. As shown in
The shaft displacing member 27′ in Example 3 is preset so that the gap d1 between the upper and lower contacting portions 27f, 27g, i.e., the gap d1 of the recess 27d in the upper and lower directions is equal to the outer diameter of the driven shaft Rja. Namely, the driven shaft Rja in Example 3 is interposed between the upper and lower contacting portions 27f, 27g in a state where a gap larger than play does not exist therebetween.
In the thus configured printer U which is an example of the image forming apparatus of Example 3, as shown in
In Example 3, there is the possibility that, between the cases shown in
In the case where the swing center 27a is not moved in the upper and lower directions, therefore, there is the possibility that the driven shaft Rja is contacted and pressed against the upper contacting portion 27f or the lower contacting portion 27g by the movement of the driven shaft Rja in the upper and lower directions, the opposite side of the swing center 27a in the movement direction of the driven shaft Rja is separated from the center supporting portion (32c1), and the swing center 27a is tilted. Therefore, the locus of rotation of the shaft displacing member 27′ which is pressed by the driven shaft Rja to be supported in a state where the swing center 27a is tilted is deviated from the right direction coincident with the tilting direction of the driven shaft Rja. In this case, when the medium conveying belt B is offset, efficient transmission of the moving force of the members B, 26 as the rotation force of the shaft displacing member 27′ is hardly performed. As a result, there is the possibility that the performance of correcting offset of the medium conveying belt B is reduced.
In order to prevent the upper contacting portion 27f or the lower contacting portion 27g from being contacted with the driven shaft Rja, the gap d1 of the recess 27d must be sufficiently long with respect to the moving distance of the driven shaft Rja, and the length of the shaft displacing member 27′ in the upper and lower directions must be increased. When the gap d1 is increased, therefore, the width lengths of the belt offset sensing member 26 and the shaft displacing member 27′ must be increased in order to ensure the contact range of the belt offset sensing member 26 and the interlocking member contacting portion (27f+27g).
In the printer U of Example 3, however, the swing center 27a is supported so as to be movable in the upper and lower directions. When the interlocking member contacting portion (27f+27g) is contacted and pressed by the movement of the driven shaft Rja in the upper and lower directions, therefore, the shaft displacing member 27′ can be moved in the upper and lower directions interlockingly with the driven shaft Rja.
In the printer U of Example 3, as compared with the case where the swing center 27a is not moved in the upper and lower directions, therefore, tilting of the swing center 27a due to pressing of the driven shaft Rja is reduced, and the shaft displacing member 27′ can be smoothly swung. As a result, in the printer U of Example 3, as compared with the case where the swing center 27a is not moved in the upper and lower directions, the performance of correcting offset of the medium conveying belt B is less reduced.
In Example 3, the gap d1 of the recess 27d in the upper and lower directions is set to be equivalent to the outer diameter of the driven shaft Rja, and the driven shaft Rja is interposed between the upper and lower contacting portions 27f, 27g in a state where a gap larger than play does not exist therebetween. As a result, in the printer U of Example 3, the shaft displacing member 27′ can be moved in the upper and lower directions interlockingly with movement of the driven shaft Rja in the stretching direction.
Furthermore, the gap d1 is set to be equivalent to the outer diameter. Even when the driven shaft Rja is moved in the upper and lower directions, the contact range of the belt offset sensing member 26 which is passed through the driven shaft Rja, and the interlocking member contacting portion (27f+27g) in which the driven shaft Rja is interposed can be always ensured in the vicinity of the driven shaft Rja. As a result, in the printer U of Example 3, the lengths of the belt offset sensing member 26 and the shaft displacing member 27′ in the upper and lower directions can be shortened, and the whole belt module BM and the whole printer U can be miniaturized.
In Example 3, the movement of the swing center 27a in the stretching direction is restricted between the upper end wall 32d and the lower end wall 32e. Namely, Example 3 is set so that the shaft displacing member 27′ is set so as to move in the upper and lower directions between the intersecting-direction most upstream position where the upper end portion is contacted with the upper end wall 32d, and the intersecting-direction most downstream position where the lower end portion is contacted with the lower end wall 32e.
As a result, in the printer U of Example 3, the movement of the shaft displacing member 27′ in the upper and lower directions can be restricted by the movement restricting portion (32d+32e), and the shaft displacing member 27′ can be prevented from moving in the upper and lower directions to drop off from the center supporting recess 32.
In other points, the printer U of Example 3 can attain the same effects as the printer U of Example 2.
(Modifications)
Although, in the above, the examples of the invention have been described in detail, the invention is not restricted to the examples. Various modifications are enabled within the scope of the spirit of the invention set forth in the claims. Modifications (H01) to (H012) of the invention will be exemplified.
(H01) Although, in the examples, the printer has been described as an example of the image forming apparatus, the invention is not restricted to this. The image forming apparatus may be a facsimile apparatus, a copier, or a multi-function apparatus having all of or a plurality of functions of these apparatuses. The invention is not restricted to an electrophotographic image forming apparatus, and the configurations of the examples may be applied to a portion of a medium conveying member in an image forming apparatus of a so-called inkjet recording system.
(H02) Although, in the examples, the photosensitive member Pk for black is placed in the upper end has been exemplarily described, the invention is not restricted to this. The placement position may be arbitrarily changed in accordance with the configuration, the design, and the like.
(H03) Although, in the examples, the movement of the medium conveying belt B is controlled by the functions of the eccentric cam HC and the transfer frame pressing spring SPc, the invention is not restricted to this. An arbitrary configuration which can move the medium conveying belt B may be employed. For example, in place of the eccentric cam HC, a so-called solenoid may be used, and, in place of the transfer frame pressing spring SPc, the weight of the transfer frame Ft itself may be used while adjusting the center of gravity position of the transfer frame Ft.
(H04) Although, in the examples, the image forming apparatus for four colors of Y, M, C, and K has been exemplarily described, the invention is not restricted to an apparatus for four colors. The invention may be applied also to an image forming apparatus for three or less or five or more colors.
(H05) Although, in the examples, the medium conveying belt B has been described as an example of the endless belt-like member, the invention is not restricted to this. For example, the invention may be applied also to endless belt-like members such as an intermediate transfer belt with and from which a belt cleaner and a secondary transferring member are contacted and separated, and which is an example of an intermediate transferring body, and an endless belt-like member such as a photosensitive belt which is an example of an image carrier. Namely, an intermediate transferring device, a transferring device, an image forming apparatus, and the like having the belt module BM which is an example of the offset correcting device of the invention may be configured.
(H06) In Example 1, the radius of curvature of the left end faces 27h is set so that the contact profile PF is arcuate, and, in contrast to the arcuate contact profile PF in Example 1, the contact profile PF′ in Example 2 exhibits an involute curve shape which extends toward the center of the arc, thereby allowing offset of the medium conveying belt B to be easily converged in the vicinity of the balanced position. The invention is not restricted to this. For example, the radius of curvature of the left end faces 27h may be set so that, in contrast to the arcuate contact profile PF in Example 1, the contact profile exhibits a cycloidal curve which extends toward the center of the arc, thereby allowing offset of the medium conveying belt B to be easily converged in the vicinity of the balanced position. As shown in
(H07) In the examples, the belt module BM is vertically placed, and hence the swing bracket SB is tilted by urging of the press springs SPb, SPb′. When the belt module BM is horizontally placed, for example, the swing bracket SB may be tilted by its own weight, and the press springs SPb, SPb′ may be omitted.
(H08) In the examples, the medium conveying belt B is set so that it is offset only in the front direction, and hence the shaft displacing member 27 or 27′ is placed only in the front end portion of the driven shaft Rja. The invention is not restricted to this. For example, the swing bracket SB and the shaft displacing member 27 or 27′ may be disposed in both the end portions of the driven shaft Rja, so that offsets of both the width-direction ends of the medium conveying belt B can be corrected.
(H09) In the examples, in accordance with the driven roll Rj which is tilted in the right direction, the shaft displacing member 27 or 27′ is placed on the right side of the driven shaft Rja. The invention is not restricted to this. In the case where the driven shaft Rja is set so that one end portion is tilted with respect to the other end portion, for example, the shaft displacing member 27 or 27′ may be set so as to be tilted in the direction opposite to that of tilting which is set in the one end portion of the driven shaft Rja with respect to the other end portion.
(H010) In Example 1, the swing center 27a of the shaft displacing member 27 is formed to have an oval section shape by the pair of cutout faces 27a1, 27a2. The invention is not restricted to this. Even when a D-like section shape or a so-called D-cut shape is formed by only one cutout face 27a1, for example, the swing center can be inserted into the cutout insertion portion 9b in a state where the posture of the shaft displacing member is fit into the cutout insertion portion 9b of the groove portion 9.
(H0111) In Example 1, the configuration is preferably employed where the swing center 27a of the shaft displacing member 27 is fit from the outside of the swing range AR2 into the cutout insertion portion 9b to prevent the shaft displacing member 27 from dropping off the groove portion 9 during a swinging operation. The invention is not restricted to this. For example, a drop-off preventing member which closes the cutout insertion portion 9b may be used to prevent the shaft displacing member 27 from dropping off the groove portion 9. Alternatively, the configuration for preventing drop-off may be omitted.
(H012) In the examples, the left end faces 27h may be set so as to have an arcuate shape having the same diameter as the arcuate locus of the contact profile PF in Example 1.
The foregoing description of the embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention defined by the following claims and their equivalents.
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