Patent Application
20100247144
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-078266 filed on Mar. 27, 2009.
1. Technical Field
The present invention relates to an intermediate transfer device, a transfer device and an image forming apparatus.
2. Related Art
In image forming apparatuses such as electrophotographic copiers and printers, a visible image formed on the photoreceptor surface is primarily transferred onto an intermediate transfer material such as an intermediate transfer belt, secondarily transferred from the intermediate transfer material onto a medium and then, fixed thereon to form an image.
A technical problem of the present invention is to suppress wrinkles caused on the intermediate transfer material as the condition of tension application to the intermediate transfer material is changed.
According to an aspect of the invention, there is provided an intermediate transfer device including an endless-belt-form intermediate transfer material whose outer surface successively passes, in a rotation direction, through regions where the outer surface is opposed to a first image holding member that holds a first image and a second image holding member that holds a second image; a first moving member that is disposed on a rear surface side of the intermediate transfer material and on a side of the first image holding member, and that is movable between a first position-1, where the first moving member applies tension to the intermediate transfer material, and a second position-1, which is farther from the intermediate transfer material than the first position-1; a second moving member that is disposed on the rear surface side of the intermediate transfer material and on a side of the second image holding member, and that is movable between a first position-2, where the second moving member applies tension to the intermediate transfer material, and a second position-2, which is farther from the intermediate transfer material than the first position-2; a first tension applying member that is disposed on an upstream side, in the rotation direction of the intermediate transfer material, of the first moving member and that applies tension to the intermediate transfer material; a second tension applying member that is disposed on a downstream side, in the rotation direction of the intermediate transfer material, of the second moving member and that applies tension to the intermediate transfer material; and a third tension applying member that is disposed on the rear surface side of the intermediate transfer material, and that applies tension to the intermediate transfer material when at least either the first moving member is moved to the second position-1 or the second moving member is moved to the second position-2, and that is separated from the intermediate transfer material when the first moving member is in the first position-1 and the second moving member is in the first position-2.
Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein:
Referring to the drawings, concrete examples of an exemplary embodiment of the present invention (hereinafter, referred to as examples) will be described; however, the present invention is not limited to the following examples:
For ease of understanding of the description that follows, in the drawings, the direction perpendicular to the plane of the figure will be referred to as X-axis direction; the right-to-left direction, as Y-axis direction; the top-to-bottom direction, as Z-axis direction; and the directions or the sides represented by the arrows X, −X, Y, −Y, Z and −Z, as forward, rearward, rightward, leftward, upward and downward, or front side, rear side, right side, left side, upper side and lower side, respectively.
Moreover, in the figure, “◯” with “•” inside indicates an arrow extending from the rear to the front of the plane of the figure, and “◯” with “x” inside indicates an arrow extending from the front to the rear of the plane of the figure.
In the following description using the drawings, for ease of understanding, illustration of members other than the members necessary for the description are omitted as appropriate.
In
The user interface UI is provided with input buttons such as a copy start key as an example of an image formation start button, a copy count setting key as an example of an image formation count setting button and a numeric keypad as an example of number input buttons, and a display device UI1.
The image input device U1, which is an example of an automatic document feeding device, is constituted by an image scanner or the like as an example of an image reading device. In
The client personal computer PC of the first example is constituted by a so-called calculating apparatus, a so-called computer apparatus, and includes a computer main unit H1 as an example of the image information transmitting apparatus main unit, a display H2 as an example of a display member, a keyboard H3 and a mouse H4 as examples of input members, and a non-illustrated hard disk drive as an example of an information storing member.
The following are provided: sheet feeding trays TR1 to TR4 as an example of a plurality of sheet feeding members; and a sheet feeding path SH1 for taking out a recording sheet S as an example of the final transfer material or a medium accommodated in the sheet feeding trays TR1 to TR4 and conveying it to the image forming apparatus main unit U3.
In
The image forming apparatus main unit U3 is also provided with: a controller C; a laser driving circuit D as an example of a latent image writing device driving circuit controlled by the controller C; and a power supply circuit E controlled by the controller C. The laser driving circuit D outputs laser driving signals corresponding to image information of green (G), orange (0), yellow (Y), magenta (M), cyan (C) and black (BK) inputted from the image input device U1, to latent image forming devices ROSg, ROSo, ROSy, ROSm, ROSc and ROSk for the colors G to K at a preset time, so-called timing.
Under the latent image forming devices ROSg to ROSk for the colors, image holding member units UG, UO, UY, UM, UC and UK for the colors G to K and developing units GG, GO, GY, GM, GC and GK for the colors G to K as an example of the developing devices are arranged so as to be detachably attachable.
The black image holding member unit UK is an example of a sixth image holding member, and is provided with a photoreceptor drum Pk for black as an example of an image holding member for black, a charging unit CCk and a cleaner CLk as an example of a cleaning device for the image holding member. On the right side of the photoreceptor drum Pk, a developing roll R0 as an example of the developing member of the black developing unit GK is disposed so as to adjoin it.
The image holding member units UG to UC for the other colors G to C are also provided with a photoreceptor drum Pg for green as an example of the first image holding member and an example of a first spot color image holding member, a photoreceptor drum Po for orange as an example of the second image holding member and an example of a second spot color image holding member, a photoreceptor drum Py for yellow as an example of the third image holding member, a photoreceptor drum Pm for magenta as an example of a fourth image holding member, and a photoreceptor drum Pc for cyan as an example of a fifth image holding member, respectively. For the photoreceptor drums Pg to Pc, corresponding charging units CCg, CCo, CCy, CCm and CCc and cleaners CLg, CLo, CLy, CLm and CLc for the colors are arranged so as to adjoin them, respectively. On the right sides of the photoreceptor drums Pg to Pc, the developing rolls R0 as an example of the developing members of the developing units GG to GC for the colors are also arranged so as to adjoin them.
In the first example, the photoreceptor drum Pk for black which is highly frequently used and whose surface is largely worn has a large diameter compared with the photoreceptor drums Pg to Pc for the other colors so that it is capable of high-speed rotation and lasts long.
The photoreceptor drum Pg for green and the photoreceptor drum Po for orange constitute two photoreceptor drums Pg and Po for the spot colors as an example of the spot color image holding members. The photoreceptor drum Py for yellow, the photoreceptor drum Pm for magenta and the photoreceptor drum Pc for cyan constitute three photoreceptor drums Py, Pm and Pc for the three colors as an example of the image holding members for the three colors.
The image holding member units UG to UK and the developing units GG to GK constitute visible image forming members (UG+GG), (UO+GO), (UY+GY), (UM+GM), (UC+GC) and (UK+GK), respectively.
In
The toner images on the surfaces of the photoreceptor drums Pg to Pk are transferred onto an intermediate transfer belt B as an example of the intermediate transfer material so as to be placed one on another by primary transfer rolls T1g, T1o, T1y, T1m, T1c and T1k as an example of intermediate transfer members in primary transfer regions Q3g, Q3o, Q3y, Q3m, Q3c and Q3k as an example of intermediate transfer regions set below, so that a multi-color image, a so-called color image is formed on the intermediate transfer belt B. The color image formed on the intermediate transfer belt B is conveyed to a secondary transfer region Q4.
When only black image data is present, only the photoreceptor drum Pk and the developing unit GK for black are used, and only a black toner image is formed.
In the first example, setting is preliminarily made so that the line segment connecting the primary transfer regions Q3y, Q3m and Q3c of the photoreceptor drums Py to Pc for the three colors and the primary transfer region Q3k of the photoreceptor drum Pk for black extends linearly.
After the primary transfer, the residual toner on the surfaces of the photoreceptor drums Pg to Pk is cleaned by the cleaners CLg to CLk for the photoreceptor drums, respectively.
The belt module BM has the intermediate transfer belt B. At the right end on the rear side of the intermediate transfer belt B, a belt driving roll Rd as an example of the first tension applying member and an example of an intermediate transfer material driving member is disposed. The belt driving roll Rd rotates the intermediate transfer belt B in the direction of the arrow Ya as the rotation direction. On the rear side of the intermediate transfer belt B, a second intermediate transfer material supporting member Rt2 as an example of the second tension applying member is disposed on the left side of the photoreceptor drum Pk for black, and a third intermediate transfer material supporting member Rt3 as an example of the fourth tension applying member is disposed between the photoreceptor drums Pg and Po for green and orange. Moreover, on the rear side of the intermediate transfer belt B, a plurality of tension rolls Rt as an example of the tension applying members that apply tension to the intermediate transfer belt B are disposed. Further, on the rear side of the intermediate transfer belt B, a walking roll Rw as an example of a meandering preventing member that prevents the intermediate transfer belt B from meandering, a plurality of idler rolls Rf as an example of driven members, and a backup roll T2a as an example of a secondary transfer opposing member are disposed.
Thus, in the belt module BM of the first example, the intermediate transfer belt B is stretched by the rolls Rd, Rt2, Rt3, Rt, Rw, Rf, T2a and the like.
Moreover, in the first example, on the upstream side in the direction of the arrow Ya of the primary transfer roll T1g for green, a first retracting roll R1 as an example of the first moving member supported so as to be movable in a contact and separation direction which is vertical to the direction of the arrow Ya is disposed. The first retracting roll R1 of the first example is supported so as to be movable between a first contact position to bring the intermediate transfer belt B in contact with the photoreceptor drum Pg for green and a first separation position to separate the intermediate transfer belt B therefrom. That is, the first retracting roll R1 is supported so as to be movable between the first contact position as an example of the first position to apply tension to the intermediate transfer belt B and the first separation position as an example of the second position farther from the intermediate transfer belt B than the first contact position.
Between the primary transfer rolls T1o and T1y for orange and yellow, a second retracting roll R2 as an example of the second moving member structured similarly to the first retracting roll R1 and a third retracting roll R3 as an example of the third moving member are arranged in a line. The second retracting roll R2 of the first example is supported so as to be movable between a second contact position to bring the intermediate transfer belt B in contact with the photoreceptor drum Po for orange and a second separation position to separate the intermediate transfer belt B therefrom. That is, the second retracting roll R2 is supported so as to be movable between the second contact position as an example of the first position to apply tension to the intermediate transfer belt B and the second separation position as an example of the second position farther from the intermediate transfer belt B than the second contact position. Moreover, the third retracting roll R3 of the first example is supported so as to be movable between a third contact position to bring the intermediate transfer belt B simultaneously in contact with the photoreceptor drums Py to Pc for the three colors and a third separation position to separate the intermediate transfer belt B simultaneously therefrom. That is, the third retracting roll R3 is supported so as to be movable between the third contact position as an example of the first position to apply tension to the intermediate transfer belt B and the third separation position as an example of the second position farther from the intermediate transfer belt B than the third contact position.
On the downstream side in the direction of the arrow Ya of the primary transfer roll T1k for black, a fourth retracting roll R4 as an example of a fourth moving member structured similarly to the retracting rolls R1 to R3 is disposed. The fourth retracting roll R4 of the first example is supported so as to be movable between a fourth contact position to bring the intermediate transfer belt B in contact with the photoreceptor drum Pk for black and a fourth separation position to separate the intermediate transfer belt B therefrom. That is, the fourth retracting roll R4 is supported so as to be movable between the fourth contact position as an example of the first position to apply tension to the intermediate transfer belt B and the fourth separation position as an example of the second position farther from the intermediate transfer belt B than the fourth contact position.
Further, between the primary transfer rolls T1c and T1k for cyan and black, a fifth retracting roll R5 as an example of a fifth moving member structured similarly to the retracting rolls R1 to R4 is disposed. The fifth retracting roll R5 of the first example is supported so as to be movable between a fifth contact position to bring either the photoreceptor drums Py to Pc for the three colors or the photoreceptor drum Pk for black, or both of them in contact with the intermediate transfer belt B and a fifth separation position to separate the photoreceptor drums Py to Pk for yellow, magenta, cyan and black from the intermediate transfer belt B. That is, the fifth retracting roll R5 is supported so as to be movable between the fifth contact position as an example of the first position to apply tension to the intermediate transfer belt B and the fifth separation position as an example of the second position farther from the intermediate transfer belt B than the fifth contact position.
In the first example, as shown in
In the first example, the second line segment L2 is inclined downward at a first angle α with respect to the first line segment L1. The third line segment L3 is inclined downward by a second angle β with respect to the first line segment L1. The fourth line segment L4 is inclined downward at a third angle γ with respect to the second line segment L2.
Thus, in the first example, the posture of the intermediate transfer belt B is preliminarily set so that the line segments L2, L3 and L4 extend so as to incline downward which is the rear side of the intermediate transfer belt B, at the angles α, β and (α+γ) with respect to the line segment L1.
Between the third intermediate transfer material supporting member Rt3 and the second retracting roll R2, a first separation-time stretching roll Rta as an example of the third tension applying member is disposed. The first separation-time stretching roll Rta of the first example is preliminarily disposed in a first separation-time contact position where it is separated from the intermediate transfer belt B when the second retracting roll R2 is moved to the second contact position and it supports the intermediate transfer belt B from the rear side when the second retracting roll R2 is moved to the second separation position.
Between the third retracting roll R3 and the fifth retracting roll R5, a second separation-time stretching roll Rtb as an example of a second third tension applying member is disposed. The second separation-time stretching roll Rtb of the first example is preliminarily disposed in a second separation-time contact position where it is separated from the intermediate transfer belt B when the retracting rolls R3 and R5 are moved to the contact positions and it supports the intermediate transfer belt B from the rear side when the third retracting roll R3 is moved to the third separation position or when the fifth retracting roll R5 is moved to the fifth separation position.
On the downstream side in the direction of the arrow Ya of the primary transfer rolls T1g to T1k for green to black, a plate-form charge removing sheet metal JB as an example of a charge removing member that removes the charge on the rear surface of the intermediate transfer belt B is disposed. The charge removing sheet metal JB of the first example is disposed out of contact with the intermediate transfer belt B, and can be disposed, for example, in a position 2 mm away from the rear surface of the intermediate transfer belt B.
The rolls Rd, Rt, Rw, Rf, T2a and R1 to R5 constitute belt supporting rolls Rd, Rt, Rw, Rf, T2a and R1 to R5 as an example of the intermediate transfer material supporting member that rotatably supports the intermediate transfer belt B from the rear side.
The intermediate transfer belt B, the belt supporting rolls Rd, Rt, Rt2, Rt3, Rta, Rtb, Rw, Rf, T2a and R1 to R5, the primary transfer rolls T1g to T1k, the charge removing sheet metal JB and the like constitute the belt module BM of the first example.
Under the backup roll T2a, a secondary transfer unit Ut is disposed. A secondary transfer roll T2b as an example of a secondary transfer member of the secondary transfer unit Ut is disposed with the intermediate transfer belt B in between so that it can separate from and come into contact with the backup roll T2a, and the secondary transfer region Q4 is formed by the region where the secondary transfer roll T2b is pressed against the intermediate transfer belt B. A contact roll T2c as an example of the voltage applying contact member abuts on the backup roll T2a, and the rolls T2a to T2c constitute a secondary transferrer T2 as an example of the final transfer member.
To the contact roll T2c, a secondary transfer voltage of the same polarity as the charging polarity of the toner is applied at preset timing by the power supply circuit controlled by the controller C.
Under the belt module BM, the sheet conveying path SH2 is disposed. The recording sheet S fed from the sheet feeding path SH1 of the sheet feeding device U2 is conveyed to the sheet conveying path SH2 by a conveying roll Ra as an example of a medium conveying member, and is conveyed to the secondary transfer region Q4 by way of a medium guiding member SGr and a pre-transfer medium guiding member SG1 by a REGE roll Rr as an example of a sheet feed time adjusting member in synchronism with the conveyance of the toner image to the secondary transfer region Q4.
The medium guiding member SGr together with the REGE roll Rr is fixedly supported by the image forming apparatus main unit U3.
The toner image on the intermediate transfer belt B is transferred onto the recording sheet S by the secondary transferrer T2 when passing through the secondary transfer region Q4. In the case of a full-color image, the toner images primarily transferred onto the surface of the intermediate transfer belt B so as to be placed one on another are secondarily transferred onto the recording sheet S collectively.
The intermediate transfer belt B after the secondary transfer is cleaned by a belt cleaner CLB as an example of an intermediate transfer material cleaning unit. The secondary transfer roll T2b and the belt cleaner CLB are supported so that it can be separated from and come into contact with the intermediate transfer belt B.
The belt module BM, the secondary transferrer T2, the belt cleaner CLB and the like constitute a transfer device TS that transfers the images on the surfaces of the photoreceptor drums Py to Po onto the recording sheet S.
The recording sheet S having the toner image secondarily transferred thereonto is conveyed to a fixing device F by way of a post-transfer medium guiding member SG2 and a sheet conveying belt BH as an example of a pre-fixing medium conveying member. The fixing device F is provided with a heating roll Fh as an example of a heat fixing member and a pressurizing roll Fp as an example of a pressurization fixing member, and a fixing region Q5 is formed by the region where the heating roll Fh and the pressurizing roll Fp are pressed against each other.
The toner image on the recording sheet S is fixed by heating by the fixing device F when passing through the fixing region Q5. On the downstream side of the fixing device F, a conveying path switching member GT1 is provided. The conveying path switching member GT1 selectively switches the recording sheet S conveyed along the sheet conveying path SH2 and having undergone heat fixing in the fixing region Q5, to either the sheet ejecting path SH3 or the sheet reversing path SH4 of the sheet processing device U4. The recording sheet S conveyed to the sheet ejecting path SH3 is conveyed to a sheet conveying path SH5 of the sheet processing device U4.
In the middle of the sheet conveying path SH5, a curl correcting device U4a is disposed, and on the sheet conveying path SH5, a switching gate G4 as an example of the conveying path switching member is disposed. The switching gate G4 conveys the recording sheet S conveyed from the sheet conveying path SH3 of the image forming apparatus main unit U3, toward either a first curl correcting member h1 or a second curl correcting member h2 according to the direction of curve, so-called curl. The recording sheet S conveyed to the first curl correcting member h1 or the second curl correcting member h2 has its curl corrected as it passes. The recording sheet S having its curl corrected is ejected from an ejecting roll Rh as an example of an ejecting member onto an output tray TH1 as an example of an output portion of the sheet processing device U4 in a condition where its image fixed surface faces upward, a so-called face-up condition.
The recording sheet S conveyed toward the sheet reversing path SH4 of the image forming apparatus main unit U3 by the conveying path switching member GT1 passes while pushing away a conveyance direction restricting member made of an elastic thin-film member, a so-called mylar gate GT2, and is conveyed to the sheet reversing path SH4 of the image forming apparatus main unit U3.
To the downstream side end of the sheet reversing path SH4 of the image forming apparatus main unit U3, the sheet circulating path SH6 and a sheet reversing path SH7 are connected, and at the part of the connection, a mylar gate GT3 is disposed. The recording sheet S conveyed to the sheet conveying path SH4 through the switching gate GT1 passes through the mylar gate GT3 to be conveyed toward the sheet reversing path SH7 of the sheet processing device U4. In the case of duplex printing, the recording sheet S conveyed along the sheet reversing path SH4 once passes through the mylar gate GT3 as it is to be conveyed to the sheet reversing path SH7, and then, is conveyed in the opposite direction, that is, switched back to have its conveyance direction restricted by the mylar gate GT3, so that the switched-back recording sheet S is conveyed toward the sheet circulating path SH6. The recording sheet S conveyed to the sheet circulating path SH6 passes through the sheet feeding path SH1 to be re-conveyed to the transfer region Q4.
On the other hand, when after the rear end of the recording sheet S conveyed along the sheet reversing path SH4 passes through the mylar gate GT2, the recording sheet S is switched back before the rear end thereof passes the mylar gate GT3, the conveyance direction of the recording sheet S is restricted by the mylar gate GT2, and the recording sheet S is conveyed to the sheet conveying path SH5 in a reversed condition. After having its curl corrected by the curl correcting member U4a, the reversed recording sheet S can be ejected onto the sheet output tray TH1 of the sheet processing unit U4 in a condition where the image fixed surface of the recording sheet S faces downward, that is, a face-down condition.
The elements represented by the reference designations SH1 to SH7 constitute a sheet conveying path SH. The elements represented by the reference designations SH, Ra, Rr, Rh, SGr, SG1, SG2, BH and GT1 to GT3 constitute a medium conveying device SU.
(Description of Links LN1 to LN4)
In
The rotation shaft 3 of the primary transfer roll T1g for green is supported by a pressing member 4 extending in the contact and separation direction and supported by the frame members of the belt module BM. The pressing member 4 of the first example has a pedestal portion 4a supported by the frame members. In the pedestal portion 4a, an elastic member accommodating space 4b extending in the contact and separation direction is formed. On the intermediate transfer belt B side of the pedestal portion 4a, a bearing portion 4c rotatably supporting the rotation shaft 3 is disposed, and on the lower surface of the bearing portion 4c, an elastic member passing through supporting portion 4d extending into the elastic member accommodating space 4b is formed. Between the pedestal portion 4a and the bearing portion 4c, a pressing spring 4e as an example of an elastic member is attached in a condition where it is accommodated in the elastic member accommodating space 4b of the pedestal portion 4a and the elastic member passing through supporting portion 4d of the bearing portion 4c passes therethrough. That is, the primary transfer roll T1g for green of the first example is supported so as to be movable in the contact and separation direction in a condition where it is pressed toward the intermediate transfer belt B by the pressing spring 4e capable of stretching and contracting along the elastic member accommodating space 4b and the elastic member passing through supporting member 4d.
At both ends in the direction of the arrow Ya of the charge removing sheet metal JB, protrusions 6 and 7 protruding outward from the front and rear ends of the charge removing sheet metal JB are formed, and the protrusions 6 and 7 are supported in a condition where they pass through a second guide groove 8 and a third guide groove 9 extending in the contact and separation direction and formed in the frame members of the belt module BM, respectively. That is, the charge removing sheet metal JB of the first example is supported so as to be movable in the contact and separation direction by the protrusions 6 and 7 being guided by the guide grooves 8 and 9.
Under the first retracting roll R1, the primary transfer roll T1g for green and the charge removing sheet metal JB, a link main unit 11 as an example of the interlocking member main unit movable in the direction of the arrow Ya is disposed so as to extend from the upstream side in the direction of the arrow Ya of the first retracting roll R1 to the downstream side in the direction of the arrow Ya of the charge removing sheet metal JB. At the upstream side end in the direction of the arrow Ya of the link main unit 11 of the first example, a first engagement-receiving portion 11a extending toward the intermediate transfer belt B is formed. On the link main unit 11, a second engagement-receiving portion 11b extending toward the intermediate transfer belt B is formed parallel to the first engagement-receiving portion 11a in a position corresponding to the downstream side in the direction of the arrow Ya of the first retracting roll R1 and the upstream side in the direction of the arrow Ya of the primary transfer roll T1g for green. Moreover, on the link main unit 11, a first coupling shaft 11c and a second coupling shaft 11d are formed in positions corresponding to the downstream side in the direction of the arrow Ya of the primary transfer roll T1g for green and the downstream side in the direction of the arrow Ya of the charge removing sheet metal JB, and a first interlocking arm 12 and a second interlocking arm 13 as examples of the first arm member and the second arm member extending toward the intermediate transfer belt B are rotatably supported by the coupling shafts 11c and 11d.
The central parts of the interlocking arms 12 and 13 of the first example are rotatably supported by a first rotation shaft 12a and a second rotation shaft 13a supported by the frame members of the belt module BM, respectively. At the upper end of the first interlocking arm 12, a first contact portion 12b is formed that extends toward the upstream side in the direction of the arrow Ya and is in contact with the rotation shaft 3 from above. At the lower end of the second interlocking arm 13, a second contact portion 13b is formed that extends toward the upstream side in the direction of the arrow Ya and is in contact with the charge removing sheet metal JB from below.
Between the engagement-receiving portions 11a and 11b, a decentering cam 14 as an example of a decentering rotating member is disposed. The decentering cam 14 of the first example is disk form in cross section, and the rotation center 14a of the decentering cam 14 is rotatably supported by the frame members of the belt module BM.
On the periphery of the decentering cam 14, the following are preset: a first end point 14b which is an end point farthest from the rotation center 14a; a second end point 14c which is an end point 90° away from the first end point 14b toward the upstream side in the direction of the arrow Yb which is an example of a decentering rotating member rotation direction; and a third end point 14d which is an end point 180° away from the first end point 14b toward the upstream side in the direction of the arrow Yb and closest to the rotation center 14a.
In the first example, setting is preliminarily made so that when the lower end of the first retracting roll R1 is supported in a condition where it is in contact with the first end point 14b of the decentering cam 14 as shown in
In this case, the lower end of the first retracting roll R1 is supported in a condition where the first engagement-receiving portion 11a of the link main unit 11 is engaged with the decentering cam 14 at the second end point 14c disposed at the upstream end in the direction of the arrow Ya of the decentering cam 14.
When the decentering cam 14 is rotated in the direction of the arrow Yb from the condition shown in
With the movement of the coupling shafts 11c and 11d toward the downstream side in the direction of the arrow Ya, the interlocking arms 12 and 13 rotate in the direction of the arrow Yc opposite to the direction of the arrow Yb with the rotation shafts 12a and 13a as the rotation center, respectively. Therefore, as shown in
Thus, the first retracting roll R1, the primary transfer roll T1g for green and the charge removing sheet metal JB move in a direction away from the photoreceptor drum Pg in synchronism with one another, so that the intermediate transfer belt B is separated from the photoreceptor drum Pg. In the first example, setting is also preliminarily made so that the first retracting roll R1, the primary transfer roll T1g for green and the charge removing sheet metal JB are separated from the intermediate transfer belt B.
When the decentering cam 14 is rotated in the direction of the arrow Yc from the condition shown in
With the movement of the coupling shafts 11c and 11d toward the upstream side in the direction of the arrow Ya, the interlocking arms 12 and 13 rotate in the direction of the arrow Yb opposite to the direction of the arrow Yc with the rotation shafts 12a and 13a as the rotation center, respectively. Therefore, as shown in
The link main unit 11, the interlocking arms 12 and 13, the decentering cam 14 and the like constitute a first link LN1 as an example of an interlocking member that synchronizes the movement of the intermediate transfer belt B responsive to the movement of the first retracting roll R1 between the first contact position and the first separation position, and the movement of the primary transfer roll T1g for green and the charge removing sheet metal JB.
In the first link LN1 of the first example, setting is preliminarily made so that the movement amount of the intermediate transfer belt B by the first retracting roll R1, the primary transfer roll T1g for green and the like and the movement amount of the charge removing sheet metal JB are the same.
Between the second retracting roll R2, and the primary transfer roll T1o for orange disposed on the upstream side in the direction of the arrow Ya of the second retracting roll R2 and the charge removing sheet metal JB, a second link LN2 as an example of the interlocking member structured similarly to the first link LN1 is disposed. Moreover, between the third retracting roll R3, and the primary transfer rolls T1y to T1c for yellow, magenta and cyan disposed on the downstream side in the direction of the arrow Ya of the third retracting roll R3 and the charge removing sheet metal JB, a third link LN3 as an example of the interlocking member structured similarly to the links LN1 and LN2 is disposed.
Further, between the fourth retracting roll R4, and the primary transfer roll T1k for black disposed on the upstream side in the direction of the arrow Ya of the fourth retracting roll R4 and the charge removing sheet metal JB, a fourth link LN4 as an example of the interlocking member structured similarly to the links LN1 to LN3 is disposed.
Since the first link LN1 and the other links LN2 to LN4 have a similar structure, detailed descriptions of the links LN2 to LN4 is omitted.
(Description of Controller C of First Example)
In
(Description of Controller of Computer Main Unit Hi of Client Personal Computer PC)
The hard disk drive of the client personal computer PC stores basic software that controls the basic operation of the client personal computer PC, a so-called operating system OS, an image formation information transmitting program AP1 as an application program, and other non-illustrated pieces of software.
(Image Formation Information Transmitting Program AP1)
The controller of the client personal computer PC has the following function implementing units:
As shown in
In
The image formation color setting image 101 also has fourteen check boxes 101a as an example of image formation color selecting buttons corresponding to the fourteen patterns. Thus, in the image formation color setting image 101 of the first example, the user can select only one of the fourteen patterns of image formation colors with the check box 101a.
The image formation color setting information storing unit C102 stores, as the image formation color setting information, the image formation colors set by the image formation color setting unit C101. The image formation color setting information storing unit C102 of the first example stores, as the image formation color setting information, any of “GOYMCK”, “GYMCK”, “OYMCK”, “YMCK”, “GYMC”, “OYMC”, “YMC”, “GO”, “GK”, “OK”, “G”, “O”, “K” and “none” selected with the check box 101a of the image formation color setting image 101.
The image information color separating unit C103 color-separates the image information on which the job is to be executed, based on the image formation color setting information stored in the image formation color setting information storing unit C102. When green (G) and orange (O) which are spot colors are included in the image formation setting information, the image information color separating unit C103 of the first example color-separates the image information so that the amounts of use of the toners of the other colors Y, M, C and K are minimized.
The image formation information transmitting unit C104 transmits, to the image forming apparatus U, image formation information including the image formation color setting information stored in the image formation color setting information storing unit C102 and the image information color-separated by the image information color separating unit C103.
(Signal Output Elements Connected to Controller C)
To the controller C, output signals of the following signal output elements UI and the like are inputted:
The user interface UI detects the inputs to the copy start key, the copy count setting key, the numeric keypad, the display device UI1 and the like, and inputs the detection signals to the controller C.
(Control-Receiving Elements Connected to Controller C)
The controller C outputs the control signals of the following control-receiving elements D1 and E:
The main motor driving circuit D1 as an example of a main driving source driving circuit drives a main motor M1 as an example of a main driving source to thereby rotate the photoreceptor drums Pg to Pk, the developing rolls R0 of the developing units GG to GK, the heating roll Fh of the fixing device F, the conveying roll Ra, the belt driving roll Rd of the belt module BM and the like through a gear as an example of the driving force transmitting member.
The power supply circuit E has a development power supply circuit E1, a charging power supply circuit E2, a transfer roll power supply circuit E3, and a heating roll power supply circuit E4.
The development power supply circuit E1 applies a development voltage to the developing rolls R0 of the developing units GG to GK.
The charging power supply circuit E2 applies a charging voltage to the charging units CCg to CCk.
The transfer roll power supply circuit E3 applies transfer voltages to the primary transfer rolls T1g to T1k and the contact roll T2c of the secondary transferrer T2.
The heating roll power supply circuit E4 applies power for heating to a heater as an example of a heating member of the heating roll Fh of the fixing device F.
(Functions of Controller C)
The controller C has the following function implementing units by programs for controlling the operations of the control-receiving elements D1 and E according to the output signals of the signal output elements UI:
The job controlling unit C1 as an example of the image forming operation controlling unit controls the operations of the latent image forming devices ROSg to ROSk, the visible image forming members (UG+GG) to (UK+GK), the transfer device TS, the fixing unit F, the medium conveying device SU and the like in response to the input of the copy start key, thereby executing a job as an example of the image forming operation.
The main motor driving controlling unit C2 as an example of the main driving source driving controlling unit controls the rotation of the main motor M1 through the main motor driving circuit D1, thereby controlling the rotations of the photoreceptor drums Pg to Pk, the developing rolls R0 of the developing units GG to GK, the heating roll Fh of the fixing device F, the conveying roll Ra, the belt driving roll Rd and the like.
The power supply circuit controlling unit C3 controls the actuation of the power supply circuit E to thereby control the supply of voltages and current to the developing rolls R0, the charging units CCg to CCk, the transfer rolls T1g to T1k and T2c, the heater of the heating roll Fh of the fixing device F and the like.
The intermediate transfer belt posture controlling unit C4 as an example of a contact and separation controlling unit and an example of an intermediate transfer member posture controlling unit is provided with: an image formation information receiving unit C4A that receives the image formation information transmitted by the image formation information receiving unit C104; a posture setting table storing unit C4B; a posture selecting unit C4C; a spot color side contact and separation controlling unit C4D; a three color side contact and separation controlling unit C4E; a black side contact and separation controlling unit C4F; and a fifth contact and separation controlling unit C4G, and controls the posture of the intermediate transfer belt B at the time of job execution.
The posture setting table storing unit C4B as an example of a posture setting information storing unit stores, as shown in
In
Moreover, the posture setting table TB prestores fourth posture setting information to move the retracting rolls R3 to R5 to the respective contact positions and move the retracting rolls R1 and R2 to the respective separation positions in response to the case where the image formation color setting information is “YMCK”. Moreover, the posture setting table TB prestores fifth posture setting information to move the retracting rolls R1, R3 and R4 to the respective contact positions and move the retracting rolls R2 and R5 to the respective separation positions in response to the case where the image formation color setting information is “GYMC”. Moreover, the posture setting table TB prestores sixth posture setting information to move the retracting rolls R2 to R4 to the respective contact positions and move the retracting rolls R1 and R5 to the respective separation positions in response to the case where the image formation color setting information is “OYMC”. Moreover, the posture setting table TB prestores seventh posture setting information to move the retracting rolls R3 and R4 to the respective contact positions and move the retracting rolls R1, R2 and R5 to the respective separation positions in response to the case where the image formation color setting information is “YMC”.
Moreover, the posture setting table TB prestores eighth posture setting information to move the retracting rolls R1 and R2 to the respective contact positions and move the retracting rolls R3 to R5 to the respective separation positions in response to the case where the image formation color setting information is “GO”.
Moreover, the posture setting table TB prestores ninth posture setting information to move the retracting rolls R1, R4 and R5 to the respective contact positions and move the retracting rolls R2 and R3 to the respective separation positions in response to the case where the image formation color setting information is “GK”. Moreover, the posture setting table TB prestores tenth posture setting information to move the retracting rolls R2, R4 and R5 to the respective contact positions and move the retracting rolls R1 and R3 to the respective separation positions in response to the case where the image formation color setting information is “OK”.
Moreover, the posture setting table TB prestores eleventh posture setting information to move the first retracting roll R1 to the first contact position and move the retracting rolls R2 to R5 to the respective separation positions in response to the case where the image formation color setting information is “G”. Moreover, the posture setting table TB prestores twelfth posture setting information to move the second retracting roll R2 to the second contact position and move the retracting rolls R1 and R3 to R5 to the respective separation positions in response to the case where the image formation color setting information is “0”. Moreover, the posture setting table TB prestores thirteenth posture setting information to move the retracting rolls R4 and R5 to the respective contact positions and move the retracting rolls R1 to R3 to the respective separation positions in response to the case where the image formation color setting information is “K”. Further, the posture setting table TB prestores fourteenth posture setting information to move all the retracting rolls R1 to R5 to the respective separation positions in response to the case where the image formation color setting information is “none”.
Thus, the first posture setting information to the fourteenth posture setting information constitute the posture setting information of the first example.
The posture selecting unit C4C selects the posture of the intermediate transfer belt B at the time of job execution based on the image formation color setting information included in the image formation information received by the image formation information receiving unit C4A and the posture setting table TB stored in the posture setting table storing unit C4B. The posture selecting unit C4C of the first example selects the posture of the intermediate transfer belt B at the time of job execution by selecting the posture setting information in the posture setting table TB corresponding to the image formation color setting information.
The spot color side contact and separation controlling unit C4D has a first spot color side contact and separation controlling unit C4D1 and a second spot color side contact and separation controlling unit C4D2, and controls the contact and separation between the photoreceptor drums Pg and Po for the spot colors G and O and the intermediate transfer belt B.
The first spot color side contact and separation controlling unit C4D1 moves the first retracting roll R1 to the first contact position when the photoreceptor drum Pg for green is used, and moves the first retracting roll R1 to the first separation position when the photoreceptor drum Pg for green is not used.
The second spot color side contact and separation controlling unit C4D2 moves the second retracting roll R2 to the second contact position when the photoreceptor drum Po for orange is used, and moves the second retracting roll R2 to the second separation position when the photoreceptor drum Po for orange is not used.
The three color side contact and separation controlling unit C4E moves the third retracting roll R3 to the third contact position when the photoreceptor drums Py to Pc for Y, M and C are used, and moves the third retracting roll R3 to the third separation position when the photoreceptor drums Py to Pc are not used.
The black side contact and separation controlling unit C4F moves the fourth retracting roll R4 to the fourth contact position when the photoreceptor drum Pk for black is used, and moves the fourth retracting roll R4 to the fourth separation position when the photoreceptor drum Pk for black is not used.
The fifth contact and separation controlling unit C4G moves the fifth retracting roll R5 to the fifth contact position when the photoreceptor drums Py to Pc for Y, M and C or the photoreceptor drum Pk for black is used, and moves the fifth retracting roll R5 to the fifth separation position when the photoreceptor drums Py to Pc or the photoreceptor drum Pk for black is not used.
Thus, the intermediate transfer belt posture controlling unit C4 of the first example controls the posture of the intermediate transfer belt B at the time of job execution by moving the retracting rolls R1 to R5 between the respective contact positions and the respective separation positions according to the posture setting information selected by the posture selecting unit C4C.
With respect to the flow of the processing by the image forming apparatus U of the first example of present invention, illustration and detailed description with reference to a flowchart are omitted since it is performed only to move the retracting rolls R1 to R5 between the respective contact positions and the respective separation positions according to the posture setting information in the posture setting table TB corresponding to the image formation color setting information when the image formation information transmitted from the image formation information transmitting program AP1 of the client personal computer PC is received.
(Working of the First Example)
In the image forming apparatus U of the first example of the present invention having the above-described structure, when an image forming operation, a so-called job is executed, electrostatic latent images on the surfaces of the photoreceptor drums Pg to Pk are developed by the toners of the colors supplied to the developing rolls R0 of the developing units GG to GK. The toner images on the surfaces of the photoreceptor drums Pg to Pk are successively primarily transferred onto the intermediate transfer belt B so as to be placed one on another by the primary transfer rolls T1g to T1k in the primary transfer regions Q3g to Q3k, thereby forming a color image. Then, the color image formed on the intermediate transfer belt B is conveyed to the secondary transfer region Q4 to be secondarily transferred onto the recording sheet S by the secondary transferrer T2. In the belt module BM of the first example, the plate-form charge removing sheet metal JB as an example of the charge removing member is disposed in a non-contact manner on the downstream side in the direction of the arrow Ya of the primary transfer rolls T1g to T1k, and the charge on the intermediate transfer belt B is removed. Consequently, it is reduced that the toner image on the intermediate transfer belt B is scrambled or scattered by being locally charged by the discharge of the primary transfer rolls T1g to T1k.
Moreover, in the image forming apparatus U of the first example, when the image formation information transmitted from the client personal computer PC is received, the condition of the tension application to the intermediate transfer belt B is changed to thereby change the posture of the intermediate transfer belt B. In the specification of the present application, the “change of the condition of the tension application” refers to a change of the positions of the belt supporting rolls Rd, Rt, Rt2, Rt3, Rta, Rtb, Rw, Rf, T2a, R1 to R5 and T1g to T1k applying tension to the intermediate transfer belt B or a change of the magnitude of the applied tension. Therefore, it includes a case where the retracting rolls R1 to R5 are moved from the respective contact positions to the respective separation positions and apply no tension and a case where the applied tension is low.
Specifically, as shown in
For example, when the image formation color setting information is “GOYMCK”, the first posture setting information in the posture setting table TB is selected, and as shown in
When the image formation color setting information included in the received image formation information is “YMCK”, the fourth posture setting information in the posture setting table TB is selected, and as shown in
Therefore, in the first example, when a so-called six-color mode, four-color mode, monochrome mode and the like are executed, the photoreceptor drums Pg to Pk not being used are separated from the intermediate transfer belt B. Consequently, in the image forming apparatus U of the first example, the time degradation such as wear of the members Pg to Pk and B are reduced. In particular, in the first example, as shown in
In the first example, when the retracting rolls R1 to R5 are moved to the respective separation positions, the retracting rolls R1 to R5 are separated from the intermediate transfer belt B, and the corresponding primary transfer rolls T1g to T1k and charge removing sheet metals JB are simultaneously separated by the link LN1 to LN4 shown in
As shown in
Moreover, in the first example, as shown in
Consequently, in the image forming apparatus U of the first example, the accuracy of the color registration can be improved compared with when the first line segment L1 is not linear, so that high-quality color images are easily formed.
Moreover, in the first example, since the visible image forming members (UY+GY) to (UK+GK) for the colors Y, M, C and K can be arranged in the horizontal direction, the visible image forming members (UY+GY) to (UK+GK) can all be arranged in the same configuration and in the same condition. Consequently, in the image forming apparatus U of the first example, the parts of the visible image forming members (UY+GY) to (UK+GK) can be made common, so that the overall manufacturing cost of the image forming apparatus U can be reduced.
With respect to the spot colors G and O not requiring a color registration accuracy as high as that required by Y, M, C and K, the parts of the visible image forming members (UG+GG) and (UO+GO) for G and O can also be made common by minimizing the first angle a shown in
Moreover, by minimizing the angles α, β and (U+γ) shown in
In this case, even if the lengths in the vertical direction between the contact positions and the separation positions of the retracting rolls R1 to R5 are made short, the posture of the intermediate transfer belt B can be changed in the fourteen patterns without the members R1 to R5, T1g to T1k and JB coming into contact with the intermediate transfer belt B, and the posture change itself is small.
Moreover, when the posture change itself is small, before and after the posture change, the change is small of the meandering amount of the intermediate transfer belt B that fluctuates with changes of the stretching rolls (RD, Rt, Rt2, Rt3, Rta, Rtb, Rw, Rf, T2a, R1 to R5, T1g to T1k, T2a) stretching the intermediate transfer belt B. Consequently, in the image forming apparatus U of the first example, the increase in meandering due to the posture change can be reduced.
In the image forming apparatus U of the first example of the present invention having the above-described structure, the photoreceptor drums Pg and Po for the spot colors are disposed on the upstream side in the Ya direction of the photoreceptor drums Py to Pk for Y, M, C and K. That is, in the upstream side end part in the Ya direction, the photoreceptor drums Pg and Po for the spot colors are disposed, and in the downstream side end part in the Ya direction, the photoreceptor drum Pk for black is disposed. Moreover, the first example supports three kinds of one-color modes of “G”, “O” and “K”, that is, single color printing, so-called monochrome modes, and as the reference colors for single color printing, three colors of green (G), orange (O) and black (K) are set.
Thus, in the image forming apparatus U of the first example, the photoreceptor drums Pg, Po and Pk for the reference colors are disposed in two or more positions, and single color printing of each reference color can be set.
The developing units GG and GO of the visible image forming members (UG+GG) and (UO+GO) for the spot colors may be loaded with an arbitrary toner as well as green (G) toner and orange (O) toner; for example, they may be loaded with colorless clear toner. Moreover, they may be loaded with, for example, a color symbolizing an organization such as a company or a group as an example of the user, so-called corporate color. Consequently, when an image of a corporate color is formed, image degradation such as poor color tone or poor color development is reduced compared with when an image of the corporate color is formed with four colors Y, M, C and K.
Moreover, in the first example, in the client personal computer PC, when the image formation color setting information includes G and O, the image information is color-separated so that the amounts of use of the toners of the other colors Y, M, C and K are minimized. Consequently, for example, when G or O is the corporate color and a large number of corporate color images are formed, the amounts of use of Y, M, C and K toners are small compared with when printing is always performed with the four colors Y, M, C and K.
Moreover, in the first example, to change the posture of the intermediate transfer belt B so that the intermediate transfer belt B is separated from the photoreceptor drums Pg to Pk not being used, the three fixed rolls Rd, Rt2 and Rt3 and the five movable rolls R1 to R5 are preliminarily disposed in the respective positions shown in
Thus, in the image forming apparatus U of the first example, the belt module BM is constituted by the minimum number of parts Rd, R1, Rt3, R2, R3, R5, R4 and Rt2 and the set values L1 to L4, α, β and γ by which a total of fourteen patterns of color settings shown in
Moreover, in the first example, when the retracting roll R2 is moved to the second separation position as shown in
As shown in
On the contrary, in the image forming apparatus U of the first example, compared with when the first separation-time stretching roll Rta is not disposed, the free lengths L2a and L2b at the second line segment L2 are short, so that the generation of the wrinkles in the Ya direction that can be caused because the distances between the stretching rolls are long, the so-called tension lines is reduced. Consequently, in the image forming apparatus U of the first example, compared with when the first separation-time stretching roll Rta is not disposed, the wrinkles caused on the intermediate transfer belt B due to the change in the condition of the tension application to the intermediate transfer belt B, that is, the tension lines are suppressed, so that image degradation such as poor transfer due to the generation of the tension lines is reduced.
Moreover, in the first example, as shown in
Moreover, in the first example, as shown in
Consequently, in the image forming apparatus U of the first example, compared with when the separation-time stretching rolls Rta and Rtb are not disposed, the generation of the tension lines due to the change in the condition of the tension application to the intermediate transfer belt B is suppressed, so that image degradation such as poor transfer due to the generation of the tension lines is reduced. In particular, when the second separation-time stretching roll Rtb is present, it is reduced that the free lengths on the upstream side in the Ya direction and on the downstream side in the Ya direction of the second separation-time stretching roll Rtb are long, so that the image degradation due to the generation of the tension lines on the upstream side in the Ya direction and on the downstream side in the Ya direction is reduced.
Next, a second example of the present invention will be described. In the description of the second example, the elements corresponding to the elements of the first example are denoted by the same reference designations, and detailed descriptions thereof are omitted.
Although the second example is different from the above-described first example in the following points, it is structured similarly to the first example in the other points:
In
Moreover, in the second example, the third intermediate transfer material supporting member Rt3 of the first example is omitted, and instead of the separation-time stretching rolls Rta and Rtb of the first example, a separation-time stretching roll Rta′ as an example of the third tension applying member is disposed under the photoreceptor drum Pm for magenta. The separation-time stretching roll Rta′ of the second example is preliminarily disposed, as shown by the broken lines in
(Description of Controller C of Second Example)
In
The image formation color setting unit C101′ has an image formation color setting image displaying unit C101′ that displays the image formation color setting image 101′ shown in
In
Moreover, in
The posture setting table storing unit C4B′ as an example of the posture setting information storing unit stores a posture setting table TB′ shown in
In
Moreover, the posture setting table TB′ prestores fourth posture setting information to move the retracting rolls R3 and R4 to the respective contact positions and move the retracting rolls R1 and R5 to the respective separation positions in response to the case where the image formation color setting information is “YMC”. Moreover, the posture setting table TB′ prestores fifth posture setting information to move the retracting rolls R1, R4 and R5 to the respective contact positions and move the third retracting roll R3 to the third separation position in response to the case where the image formation color setting information is “GK”.
Moreover, the posture setting table TB′ prestores sixth posture setting information to move the retracting rolls R4 and R5 to the respective contact positions and move the retracting rolls R1 and R3 to the respective separation positions in response to the case where the image formation color setting information is “K”. Moreover, the posture setting table TB′ prestores seventh posture setting information to move the first retracting roll R1 to the first contact position and move the retracting rolls R3 to R5 to the respective separation positions in response to the case where the image formation color setting information is “G”.
Further, the posture setting table TB′ prestores eighth posture setting information to move all the retracting rolls R1 to R5 to the respective separation positions in response to the case where the image formation color setting information is “none”.
Thus, the first posture setting information to the eighth posture setting information constitute the posture setting information of the second example.
The posture selecting unit C4C′ of the second example selects the posture of the intermediate transfer belt B at the time of job execution by selecting the posture setting information in the posture setting table TB′ stored in the posture setting table storing unit C4B′ corresponding to the image formation color setting information included in the image formation information received by the image formation information receiving unit C4A.
(Working of Second Example)
In the image forming apparatus U of the second example of the present invention having the above-described structure, as shown in
For example, when the separation-time stretching roll Rta′ is disposed on the upstream side in the Ya direction of the intersection point position, the free length between the fixedly supported stretching rolls Rta′ and Rt2 when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction is longer than the free length between the fixedly supported stretching rolls Rd and Rta′ when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction. Conversely, for example, when the separation-time stretching roll Rta′ is disposed on the downstream side in the Ya direction of the intersection point position, the free length between the stretching rolls Rd and Rta′ when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction is longer than the free length between the stretching rolls Rta′ and Rt2 when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction.
On the contrary, in the second example, since the separation-time stretching roll Rta′ is disposed in the intersection point position, compared with when it is not disposed in the intersection point position, the free lengths between the fixedly supported stretching rolls Rd and Rta′ and stretching rolls Rta′ and Rt2 are never too long when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction and when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction.
Consequently, in the image forming apparatus U of the second example, only either when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction or when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction, it is reduced that the free length is long, and the generation of the tension lines shown in
Moreover, for example, when the separation-time stretching roll Rta′ is disposed on the upstream side in the Ya direction of the intersection point position, the tension that the separation-time stretching roll Rta′ applies to the intermediate transfer belt B is higher when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction than when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction. Conversely, for example, when the separation-time stretching roll Rta′ is disposed on the downstream side in the Ya direction of the intersection point position, the tension that the separation-time stretching roll Rta′ applies to the intermediate transfer belt B is higher when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction than when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction.
On the contrary, in the second example, since the separation-time stretching roll Rta′ is disposed in the intersection point position, the tension that the separation-time stretching roll Rta′ applies to the intermediate transfer belt B can be made the same between when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction and when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction.
Consequently, in the image forming apparatus U of the second example, only either when the posture of the intermediate transfer belt B is changed by a descent on the upstream side in the Ya direction or when the posture of the intermediate transfer belt B is changed by a descent on the downstream side in the Ya direction, the tension by the separation-time stretching roll Rta′ is high, and it is reduced that the tension distribution of the entire intermediate transfer belt B is biased.
In addition, the image forming apparatus U of the second example capable of development of up to five colors produces similar effects to the image forming apparatus U of the first example capable of development of up to six colors.
(Modifications)
While the examples of the present invention have been described in detail, the present invention is not limited to the above-described examples but various modifications may be made within the scope of the gist of the present invention described in claims. Modifications (H01) to (H013) of the present invention will be shown below.
(H01) While the image forming apparatus U is a so-called multifunction apparatus in the above-described examples, the present invention is not limited thereto; the image forming apparatus U may be, for example, a printer or a fax.
(H02) In the above-described examples, the image forming apparatus U is not limited to one using toners of five colors or six colors but may be, for example, one using toners of not more than four colors or not less than seven colors.
(H03) While toners of six colors: green (G); orange (O); yellow (Y); magenta (M); cyan (C); and black (K) are used in the above-described examples, the present invention is not limited thereto; for example, toners of colors other than the above-mentioned six colors may be used instead of the toners of green (G) and orange (O). In addition, the following may be used: colorless toner for coating the image surface for waterproofing and protection; and magnetic toner for forming a magnetic wire of a preset configuration and arrangement, for example, linear, in the image on the printing sheet for theft prevention or the like. A theft preventing apparatus that detects a magnetic pulse generated from the magnetic wire is described, for example, in Japanese Unexamined Patent Application Publication No. 2006-256124, and is known.
(H04) While in the above-described examples, the primary transfer rolls T1g and T1k opposed to the photoreceptor drums Pg to Pk are disposed in the primary transfer regions Q3g to Q3k, the present invention is not limited thereto; for example, non-contact-type primary transfer corotrons may be disposed instead of the primary transfer rolls T1g to T1k. In this case, by preliminarily disposing the primary transfer corotrons so that even when the retracting rolls R1 to R5 are moved to the separation positions, the corresponding primary transfer corotrons not being used are out of contact, the effects of the present invention are produced without the primary transfer corotrons interlocking with the movements of the retracting rolls R1 to R5 and the charge removing sheet metals JB.
(H05) While in the above-described examples, the intermediate transfer belt B and the photoreceptor drums Pg to Pk are brought into contact with and separated from each other by moving the rolls R1 to R5 and T1g to T1k between the contact positions and the separation positions, the present invention is not limited thereto; for example, the effects of the present invention are also produced in a structure where the retracting rolls R1 to R5 are omitted, only the primary transfer rolls T1g and T1m are moved between the contact positions and the separation positions and the movement of the intermediate transfer belt B by the primary transfer rolls T1g to T1m and the movement of the charge removing sheet metals JB are synchronized with each other. That is, the primary transfer rolls T1g to T1m may be provided with the functions of the retracting rolls R1 to R5.
(H06) While in the above-described examples, the charge removing sheet metals JB are disposed out of contact with the intermediate transfer belt B, the present invention is not limited to this structure; for example, a structure may be adopted in which instead of the charge removing sheet metals JB, conductive nonwoven cloths or charge removing brushes as an example of the charge removing member are made in contact with the intermediate transfer belt B. In this case, structures similar to the links LN1 to LN4 are provided so that the movement of the intermediate transfer belt B and the movement of the conductive unwoven cloths or the charge removing brushes are synchronized with each other, and by a change of the pressing force of the conductive unwoven cloths or the charge removing brushes and separation, the conveyance resistance of the intermediate transfer belt B and the charge removing performance are prevented from changing.
(H07) In the first example, by providing, in addition to the separation-time stretching rolls Rta and Rtb, a similar separation-time stretching roll in one or more positions in order to reduce the generation of the tension lines shown in
(H08) While in the first example, it is preferable to dispose the stretching rolls (Rd, Rt, Rt2, Rt3, R1 to R5, T1g to T1k) so that the line segments L1 to L4 shown in
(H09) While in the first example, the line segments L1 to L4 extend in the right-to-left direction and in the inclination directions thereof in order to dispose the visible image forming members (UY+GY) to (UK+GK) for Y, M, C and K as horizontally as possible and in particular, the first line segment L1 extends horizontally, the present invention is not limited thereto; for example, the line segments L1 to L4 may extend in the top-to-bottom direction and in the inclination directions thereof in order to dispose the visible image forming members (UY+GY) to (UK+GK) for the colors so as to extend as vertically as possible. In this case, in particular, it is preferable that the first line segment L1 extends vertically.
(H010) While in the examples, the photoreceptor drums Py to Pc for the three colors are simultaneously separated from the intermediate transfer belt B by the link L3 when the third retracting roll R3 is moved to the third separation position, the present invention is not limited thereto; for example, by providing separate retracting rolls and links corresponding to the photoreceptor drums Py to Pc for Y, M and C, the photoreceptor drums Py to Pc for the three colors can be structured either so as to be simultaneously separated from the intermediate transfer belt B or so as to be individually separated therefrom.
(H011) While in the examples, the photoreceptor drums Pg and Po for the spot colors are disposed on the upstream side in the Ya direction of the photoreceptor drums Py to Pk for Y, M, C and K, the present invention is not limited thereto; for example, they may be disposed on the downstream side in the Ya direction of the photoreceptor drum Pk for black or disposed between the photoreceptor drums Py to Pk for Y, M, C and K. Moreover, for example, a structure may be adopted in which only the photoreceptor drum Po for orange is disposed on the downstream side in the Ya direction of the photoreceptor drum Pk for black.
(H012) While in the first example, the following fourteen patterns shown in
(H013) In the first example, the third angle β shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-078266 | Mar 2009 | JP | national |
