Patent Grant
7885588
This patent specification claims priority from Japanese Patent Application Nos. JP2006-314800, filed on Nov. 21, 2006, and JP2007-177707, filed on Jul. 5, 2007 in the Japan Patent Office, the entire contents of each of which are hereby incorporated by reference herein.
1. Field of the Invention
The present invention generally relates to a transfer assembly used in an electronographic tandem image forming apparatus including a laser printer, an LED (light-emitting diode) printer, a facsimile machine, etc., and an electronographic tandem image forming apparatus including the transfer assembly.
2. Discussion of the Background
In recent years, tandem image forming apparatuses have attracted attention as color image forming apparatuses because there is a need to output full color images as fast as a speed with which monochrome images are output.
Tandem image forming apparatuses include a plurality of photoreceptors and a transfer assembly including a plurality of transferers and an intermediate transfer belt or a transfer and transport belt. A different color image is formed on each of the photoreceptors. Two method are used to transfer images on the photoreceptors, a direct transfer belt method and an intermediate transfer belt method.
In the direct transfer belt method, the images are transferred sequentially by transferers and superimposed one on another directly onto a recording medium that is transported by a transfer and transport belt. In the intermediate transfer method, the images are transferred sequentially by transferees and superimposed one on another on an intermediate transfer belt, and then the superimposed image is transferred by a secondary transferee onto the recording medium. In both methods, the transferees in the transfer assembly are facing one of the photoreceptors via the transfer and transport belt or the intermediate transfer belt.
Although transferees typically include a conductive rubber or a conductive sponge material, which deteriorates over time, compatibility thereof is rarely considered because useful life thereof is longer than that of the intermediate transfer belt or the transfer and transport belt included in the transfer assembly together with the transferees.
Further, when a transferer including a conductive rubber or a conductive sponge material is touched by hand during maintenance work, the transferer may be stained, deformed, or damaged. Although an axis of the transferee can be touched, the axis is typically unexposed.
Image forming apparatuses typically manage the useful life of the transfer assembly based on usage history thereof, such as the number of sheets printed, and do not manage the useful life of the transferees included therein individually.
In a related-art image forming apparatus, transfer rollers are held in sub-frames in a transfer belt assembly as shown in
The black sub-frame 350 and the full-color sub-frame 360 are for simplifying engagement and disengagement of the transfer rollers 370 with/from the transfer belt 300. More specifically, in monochrome printing, the three transfer rollers 370 held in the full-color sub-frame 360 are disengaged from the transfer belt 301 altogether by an action of the full-color sub-frame 360 because these transfer rollers 370 are not used. In color printing, all three transfer rollers 370 engage the transfer belt 301 by an action of the full-color sub-frame 360.
However, in the configuration described above, replacing individual transfer roller 370 is not easy. For example, when one of the three transfer rollers 370 held in the full-color sub-frame 360 is to be replaced at the end of its useful life, it is necessary to remove the bearing 380 and the spring 390. To save trouble removing the bearing 380 and the spring 390, the full-color sub-frame 360 should be replaced with a new one, thus wasting the other two transfer rollers 370 that are still useful.
In view of the foregoing, in one illustrative embodiment of the present invention, a transfer assembly is included in an image forming apparatus including a plurality of image carriers each configured to carry a toner image. The transfer assembly includes a plurality of transferers, a supporter, and a plurality of transferer holders. The plurality of transferers is each configured to electrostatically transfer the toner image on one of the image carriers onto one of an intermediate transfer member and a recording medium. The supporter is configured to support the plurality of transferers. The plurality of transferer holders are each configured to hold one of the plurality of transferees. Each of the plurality of transferer holders and the transferer held thereby form an integrated individual unit independently attachable to and detachable from the supporter.
In another illustrative embodiment of the present invention, an image forming apparatus includes a plurality of image carriers each configured to carry a toner image thereon and the transfer assembly described above.
A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve a similar result.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views thereof, and particularly to
Referring to
Suffixes B, Y, C, and M attached to reference numerals indicate that components indicated by those reference numerals are for forming black, yellow, cyan, and magenta toner images, respectively.
At positions facing the photoreceptor drums 1B, 1Y, 1C, and M1 via the intermediate transfer belt 3, primary transfer rollers 4B, 4Y, 4C, and 4M are provided. A power source, not shown, applies a primary transfer bias to each of the primary transfer rollers 4B, 4Y, 4C, and 4M. The image forming apparatus A further includes a cleaner 5 facing the tension roller 7 via the intermediate transfer belt 3, and a secondary transfer roller 15 facing the tension roller 6 via the intermediate transfer belt 3.
The image forming apparatus A further includes a fixer 16 located downstream from a place where the tension roller 6 and the secondary transfer roller 15 contact each other via the intermediate transfer belt 3 in a sheet transport path, and a pair of discharge rollers 17 located downstream of the fixer 16.
On the photoreceptor drums 1B, 1Y, 1C, and 1M, electrostatic latent images are formed in charge and exposure processes. The electrostatic latent images are developed with black, yellow, cyan, and magenta toners, respectively, and then transferred and superimposed one on another on the intermediate transfer belt 3 by the primary transfer rollers 4B, 4Y, 4C, and 4M, respectively. Thus, a superimposed toner image (full color image) is formed in a primary transfer process.
The image forming apparatus A further includes a sheet feeder 10, located at a bottom portion thereof, and a controller 56. The sheet feeder 10 includes a sheet cassette 11, from witch a sheet of recording media is fed by a feed roller 12, and transported through the sheet transport path by a pair of transport rollers 13 to a pair of registration rollers 14. The controller 56 includes a CPU (central processing unit), a RAM (random access memory), a ROM (read only memory), etc.
The registration rollers 14 stop the sheet, and then forward the sheet to a secondary transfer nip, which is a place where the intermediate transfer belt 3 and the secondary transfer roller 15 contact each other, such a way that the sheet overlaps the superimposed toner image. The superimposed toner image is then transferred from the intermediate transfer belt 3 onto the sheet at the secondary transfer nip in a secondary transfer process.
After the fixer 16 thermally fixes the full color image on the sheet, the discharge rollers 17 discharge the sheet from the image forming apparatus A.
As described above, the image forming apparatus A shown in
Referring to
As shown in
The sub-frames 35 and 36 are further described below.
As shown in
Referring to
The individual roller unit 40 includes a frame 41 as a holder to hold the primary transfer roller 4, a bearing 43 configured to support a roller axis 42 of the primary transfer roller 4, and a screw hole 51. Reference numeral D1, indicates a distance between a center of the screw hole 51 and a center of the roller axis 42.
Referring to
As illustrated in
The pin 47A on the back surface of the plate 47 penetrates the slot 361 from outside the sub-frame 36, with a tip thereof engaging the bearing 43 from a side opposite the side of the roller axis 42. The step screw 48 penetrating the plate 47 further penetrates the slot 361 from outside, with a tip thereof engaging the screw hole 51 on the frame 41 of the individual roller unit 40. With the engagement described above, the sub-frame 36 supports the individual roller units 40 for yellow, cyan, and magenta.
As illustrated in
The bearing 43 is electrically conductive, and the power source, not shown, applies a transfer bias to the primary transfer roller 4 through the springs 46.
According to the present embodiment, the primary transfer roller 4 and components to hold the primary transfer roller 4, such as the frame 41 and the bearing 43, form each integrated individual roller unit 40 attachable to and detachable from the transfer belt assembly 30. Further, each individual roller unit 40 is independently attachable to and detachable from the transfer belt assembly 30. Therefore, when the useful life of one of the primary transfer rollers 4 ends, only that primary transfer roller 4 need to be replaced and can be done so easily, without removing and reinstalling the bearings 43, the springs 46, etc.
Further, because the primary transfer roller 4 is not attached to and detached from the transfer belt assembly 30 singularly, a user need not hold the small roller axis 42 when detaching the primary transfer roller 4 from the transfer belt assembly 30 so as not to soil his/her hands. Further, protecting the primary transfer roller 4 with the frame 41 can prevent or reduce stains on and/or damage to the primary transfer roller 4 that are caused by hand contact or by contact with other components during replacement.
Further, cost can be reduced by integrating a replacement part and related components in a unit having a similar or identical configuration applicable to different types of image forming apparatuses. For example, in tandem type image forming apparatuses, the configuration of a unit including transfer members may differ according to type, although each transfer member and a configuration around the transfer member are similar or the same.
For example, assume that there are image forming apparatus models B1 and B2. The model B1 uses a transfer belt assembly similar to the transfer belt assembly 30 illustrated in
In these cases, when one of the primary transfer rollers for yellow, cyan, and magenta is to be replaced in each of the models B1 and B2, it is necessary to replace a whole full color unit including these three primary transfer rollers together with a sub-frame thereof. Moreover, because the pitch between the primary transfer rollers is different in the models B1 and B2, the models B1 and B2 cannot use the same type of full color unit.
By contrast, the image forming apparatus A according to the present embodiment uses integrated individual roller units 40, in each of which one primary transfer roller 4 and related components are configured as a unit. Therefore, the individual roller unit 40 can be used in common with another type of image forming apparatus, regardless of the pitch between the primary transfer rollers 4. Therefore, cost can be reduced by integrating a replacement part with related components as a common unit usable in different image forming apparatus types.
As described above, in the transfer belt assembly 30 shown in
In the present embodiment, the individual roller units 40 for black, yellow, cyan, and magenta have a similar configuration. Therefore, it is not necessary for a user to stock four individual roller units 40, one each for black, yellow, cyan, and magenta. As long as the user has one individual roller unit 40 in stock, when the useful life of one of four individual roller units 40 ends, the user can replace the individual roller unit 40 with the stock, regardless of color.
Because the individual roller units 40 for black, yellow, cyan, and magenta are similar to each other, the frames 41 of the individual roller units 40 also have an attachment part whose disposition pattern is similar to each other. The attachment part is a part which fasteners to fix the individual roller unit 40 to one of the sub-frame 35 and 36 engage. Although in the present embodiment the fasteners are the step screw 48 and the pin 47A on the plate 47, the fasteners may be any items that detachably attach the individual roller unit 40 to one of the sub-frame 35 and 36. The attachment part includes the screw hole 51 and the bearing 43, which the step screw 48 and the pin 47A on the frame 47 engage.
The attachment part, the screw hole 51 and the bearing 43 are provided at each of the side plates of the frame 41 facing each other. As shown in
As described above, the four individual roller units 40 have a similar arrangement pattern, and positions to attach the fasteners, the step screw 48 and the pin 47A on the plate 47, are the same or similar in the four individual roller units 40. Therefore, because the four individual roller unit 40 can be attached to or detached from the transfer belt assembly 30 in a similar procedure, replacement thereof can be simplified.
Referring to
The individual roller unit 40A is for one of yellow, cyan, and magenta, and holds a primary transfer roller 4, which faces one of photoreceptor drums 1Y, 1C, and 1M shown in
As illustrated in
There are several types of image forming apparatuses including a transfer belt assembly whose configuration is similar. However, a different transfer belt assembly is necessary for each type of image forming apparatus, if specification, usage condition, etc., of a transferer included in the transfer belt assembly are different.
By contrast, in the present embodiment of the present invention, a unit including a replacement part can be used in different image forming apparatus types, and thus cost can be reduced. Further, providing different integrated individual roller unit types, for example, a high quality item and a low cost item, means providing different transfer belt assembly types, and thus product line can be expanded and needs of individual customers can be satisfied.
In the configuration described above, because adjusting a position of the spring 46 between the sub-frame 36A and the frame 41A, putting the spring 46 into a hole provided on the frame 41A, etc., are unnecessary, replacement can be simplified. However, there may be a case in which a bias to a primary transfer roller (tension of a spring) differs depending on transfer belt unit type. In such a case, the same integrated individual roller unit can not be used in different transfer belt unit types. By contrast, because the spring 46 is fixed on the sub-frame 36 in the individual transfer unit 40 shown in
In the individual roller unit 40A for full color shown in
By contrast, in the individual roller unit 40B shown in
In the present embodiment, as shown in
When individual roller units for full color and black have different configurations, disposition patterns of attachment parts thereof are typically different and thus prevent installation of the wrong individual roller unit. However, if the disposition patterns of attachment parts are different, then attachment and detachment procedures are also different, and can be hard to remember.
By contrast, in the present embodiment, the individual roller unit 40A for full color and the individual roller unit 40B for black have attachment parts whose disposition patterns are the same or substantially similar to each other. The disposition pattern has following features: The screw holes 51 on both side plates of both the frames 41A and 41B, which are aligned horizontally, have the same or substantially the same diameter. The screw holes 51 on both side plates are aligned horizontally. On each side plate of both the frames 41A and 41B, the two screw holes 51 are located horizontally at a distance D1.
The attachment parts of the individual roller unit 40A for full color and the individual roller unit 40B for black have the same or substantially the same disposition pattern as well, and thus prevent installation of the wrong individual roller unit.
In the present embodiment, a concavity and a convexity that engage each other are provided on the sub-frame 36A for full color and the frame 41A of the individual roller unit 40A for full color as identification of full color. Similarly, a concavity and a convexity that engage each other are provided on the sub-frame for black and the frame 41B of the individual roller unit 40B for black as identification of black. The individual roller unit 40B for black can not be attached to the sub-frame 36A for full color, because the concavity and the convexity provided on the individual roller unit 40B and the sub-frame 36A for full color do not match. Similarly, the individual roller unit 40A for full color can not be attached to the sub-frame for black, because the concavity and the convexity on the individual roller unit 40A and the sub-frame for black do not match.
Alternatively, attachment of the wrong individual roller unit may be prevented in a control method.
The individual roller unit 40B1 is attachable to the sub-frame 36A for full color shown in
Although in a case of the individual roller unit 40B1, the roller 52 is used as a nip former, alternatively, another type of member to contact and press the intermediate transfer belt 3, such as a conductive film (e.g., Mylar™), may be used as the nip former. Further, the roller 52 may be located downstream of the primary transfer roller 4B. With the roller 52, a reliable transfer nip can be formed, and thus high quality images can be attained.
Referring to
Therefore, in the individual roller unit 40B2, the conductive film 55 discharges the intermediate transfer belt 3 in the small gap area, with the unfixed end thereof being in contact with the back surface of the intermediate transfer belt 3 and the fixed end thereof grounded. Thus, an occurrence of separation discharge can be prevented or reduced by preventing a transfer current from flowing to the small gap area.
It is to be noted that in an area immediately upstream from an entry portion of the transfer nip in the belt rotation direction, where the intermediate transfer belt 3 and the photoreceptor drum 1B start to contact each other, another small gap is formed (upstream gap) between the intermediate transfer belt 3 and the photoreceptor drum 1B. Accordingly, because a discharge phenomenon may also occur in the upstream gap area as well, another discharger may be provided therein.
Although the conductive film 55 is used as the discharger in the individual roller unit 40B2, the discharger is not limited thereto. Therefore, another type of discharger, such as a roller, may be provided in the individual roller unit 40B2. Further, the individual roller unit 40B2 may include a member to apply a bias to the intermediate transfer belt 3 depending on transfer conditions, not only to discharge the intermediate transfer belt 3. With the conductive film pressed against the back surface of the intermediate transfer belt 3, scattering of toner, honeycomb-shaped toner absence, etc., which occur after transferring, can be prevent or reduced, and thus high quality images can be attained.
As described above, the transfer belt assembly 30, shown in
Management of the useful life of the individual roller unit 40 performed by the controller 56 is described below.
As described above, the image forming apparatus A shown in
Specially, the controller 56 stores usage history information about each of the individual roller unit 40 in the history recorder 59, which is included in the RAM of the controller 56 in an example embodiment. The usage history information includes operating time of the individual roller unit 40 while being attached to the transfer belt assembly 30, the number of sheets printed, etc. When the operating time, the number of sheets, etc., reach a given value, the controller 56 issues a message to advise a user to replace the individual roller unit 40, determining that the useful life of the individual roller unit 40 is at an end.
When the individual roller unit 40 at the end of its useful life is replaced with another one, the usage history information in the history recorder 58 (RAM) should be reset. However, the newly attached individual roller unit 40 is not necessarily unused. Therefore, when the newly attached individual roller unit 40 is unused, the newness indicator 57, which is provided for each individual roller unit 40, indicates its being unused (unused state) to the controller 56. The controller 56 determines whether or not the newly attached individual roller unit 40 is unused by referring to the newness indicator 57 when detecting an attachment of the individual roller unit 40 to the transfer belt assembly 30. The controller 56 then resets the usage history information corresponding to the individual roller unit 40 for that color when determining that the newly attached individual roller unit 40 is unused.
By contrast, when the controller 56 determines that the newly attached individual roller unit 40 is not unused, the controller 56 informs the user of that fact, for example, by displaying a message on a display of the image forming apparatus A. The message may be a warning that the end of the useful life of the individual roller unit 40 cannot be properly predicted, as well as a query as whether or not to continue to attempt to manage the newly attached individual roller unit 40. When the user elects to manage the useful life end timing, for example, by pushing a button, the controller 56 resets the usage history information. When the user selects not to manage the useful life end timing, the controller 56 suspends managing the useful life end timing of that individual roller unit 40 until that individual roller unit 40 is replaced with another one.
Further, the configuration described above can relieve the user of renewing the usage history information manually. More specifically, when the individual roller unit 40 in the transfer belt 30 is replaced, the usage history information stored in the history recorder 58 should be renewed. If a user renews the usage history information for himself/herself, it may take some time and the user may forget to rewrite some of the information.
By contrast, in the image forming apparatus A, the individual roller unit 40 includes the newness indicator 57, and the controller 56 detects the newness indicator 57 and renews the usage history information automatically more quickly and without omission.
In an example embodiment, the newness indicator 57 is a mechanical structure. For example, the newness indicator 57 includes a specular reflector and a shutter both provided on the frame 41, and each of the sub-frames 35 and 36 includes a claw and a reflective photosensor. The shutter is slidable to an open position to expose the specular reflector and a closed position to cover the specular reflector. The shutter is at the closed position when an individual roller unit 40 is shipped to a user.
When the user removes an individual roller unit 40 at the end of its useful life from the sub-frame 35 or 36, the claw thereon opens the shutter. With the opened shutter, the individual roller unit 40 is recognizable as being used. More specifically, when the used individual roller unit 40 is attached to one of the sub-frame 35 and 36, the reflective photosensor thereon receives light reflected by the specular reflector, and thus the individual roller unit 40 is detected as being used. The controller 56 detects that an individual roller unit 40 as being unused when the reflective photosensor does not receive such reflected light.
Another management method of useful life of the individual roller unit 40 is described below.
Although life end timing of individual roller units 40 is managed for each color similarly in this method, instead of a mechanical structure, the usage history manager 59 shown in
When the transfer belt assembly 30 shown in
In the usage history manager 59 as a the circuit board, both a newness indicator 57 and a history recorder 58 are included in the same IC chip. The newness indicator 57 includes newness determination information, which indicates being unused (unused state) as factory default. The newness indicator 57 further includes color identification indicating one of black, yellow, cyan, and magenta, which the individual roller unit 40 is for. When a user starts using the individual roller unit 40, the controller 56 renews the newness determination information to a value showing being used. Therefore, the controller 56 determines whether or not the individual roller unit 40 is unused based on the newness determination information stored in the newness indicator 57 in the usage history manager 59 (circuit board). Further, the controller 56 detects an error when the wrong individual roller unit 40 is attached to the image forming apparatus A based on the color identification.
As described above, in the image forming apparatus A according to the present embodiment, the individual roller unit 40 is provided with the newness indicator 57. Therefore, whether or not an individual roller unit 40 is unused and an error message indicating that the individual roller unit 40 is for the wrong color are detected through coordination between functions of the controller 56 and the newness indicator 57.
Further, in the present embodiment, the usage history manager 59 (circuit board) of the individual roller unit 40 includes the history recorder 58, and usage history information is managed through coordination between the functions of the controller 56 and the history recorder 58.
By contrast, when the history recorder 58 is included in the controller 56 with the usage history information managed only by the controller 56, the remaining life of a used individual roller unit 40 is not recognizable even if the individual roller unit 40 is detached from the image forming apparatus A before the end of its useful life. However, if the detached individual roller unit 40 is not used until its useful life ends, the individual roller unit 40 can be reused.
Therefore, in the present embodiment, by providing the individual roller unit 40 with the history recorder 58 is the form of an IC chip, etc., usage history information can be included in the individual roller unit 40, facilitating reuse or recycling of used individual roller units 40.
The usage history information stored in the history recorder 58 includes the operating time of the primary transfer roller 4 held in that individual roller unit. In this case, the useful life of the individual roller unit 40 is managed based on useful life of the primary transfer roller 4. However, in addition to the useful life of the primary transfer roller 4, the operating time of the bearings 43, the springs 46, and other components in the individual roller unit 40 may be stored so that individual component can be reused. In this case, the individual roller unit 40 is replaced with another one when one of the components reaches the end of its useful life, and other components whose operating time is relatively short can be prepared for reuse at a recycling factory.
In the example embodiments shown in
A method of determining the end of the useful life of a unit or a component is described below.
Although the end of the useful life of a component can be determined with a certain degree of accuracy by storing operating time as usage history information as in the embodiments described above, the relation between deterioration and operating time is typically different for each component. As a result, a predicted end of useful life might be slightly different from the actual end of useful life.
Therefore, in an example embodiment of the present invention, the controller 56 measures a degradation level of the primary transfer roller 4 so as to determine the end of its useful life with a higher degree of accuracy. The degradation level of the primary transfer roller 4 means the level of degradation of the conductive rubber layer included therein. The degradation level of the primary transfer roller 4 is determined based on relations among electric resistance of the conductive rubber layer, a transfer bias, and temperature, which are further described below.
The individual roller unit 40 further includes a conductive feedback current roller in addition to the primary transfer roller 4. The conductive feedback current roller is configured to contact the intermediate transfer belt 3 at a portion downstream of the primary transfer roller 4 in the belt rotation direction. The transfer current applied to the back surface of the intermediate transfer belt 3 by the primary transfer roller 4 partly flows in a thickness direction of the intermediate transfer belt 3 to the photoreceptor drum 1. This current is an actual transfer current and affects a toner image on the photoreceptor drum 1. In the transfer nip and an area around the transfer nip, the transfer current applied by the primary transfer roller 4 partly flows in a circumferential direction of the intermediate transfer belt 3, this current is hereinafter referred to as the circumferential current. A ratio of the circumferential current to the actual transfer current depends on the electrical resistance of the intermediate transfer belt 3, which changes as the temperature changes. If this ratio fluctuates, reliable transfer characteristics can not be attained.
Therefore, in the image forming apparatus A according to the present embodiment, a bias output from the power source is controlled so as to maintain the actual transfer current constant. More specifically, most of the circumferential current flows to the feedback current roller as a feedback current. The power source for supplying the transfer bias calculates the actual transfer current by deducting the feedback current from an output current, and controls the output bias to maintain the actual transfer current constant.
The image forming apparatus A further includes a temperature sensor, not shown, to detect temperature therein and output a detection result as a digital temperature signal to the controller 56. The power source to supply the transfer bias outputs a value of the transfer bias applied to the primary transfer roller 4 to the controller 56 as a digital bias signal. When the temperature signal from the temperature detector indicates a predetermined or given temperature (e.g., 25° C.), in other words, when an electric resistance of the intermediate transfer belt 3 corresponds to the predetermined or given temperature, the controller 56 reads the bias signal. The bias signal correlates with electric resistance of the conductive rubber layer in the primary transfer roller 4. That is, a transfer bias value under a given temperature increases as the electric resistance of the conductive rubber layer increases in accordance with the degradation of the conductive rubber layer. Therefore, the controller 56 determines a degradation level of the primary transfer roller 4 based on a bias signal under a given temperature, and stores the determined degradation level in the history recorder 58.
It is to be noted that the transfer belt assembly 30 can be adopted in a tandem image forming apparatus employing a direct transfer belt method, although the description above concerns a tandem image forming apparatus employing an intermediate transfer method.
Referring to
As illustrated in
At positions facing the photoreceptor drums 1B, 1Y, 1C, and 1M via the transfer belt 3A, transfer rollers 4AB, 4AY, 4AC, and 4AM are provided. The image forming apparatus A1 further includes a cleaner 5 facing the tension roller 21 via the transfer belt 3A.
The image forming apparatus A1 further includes a fixer 16 having a heating belt located downstream of the image forming unit 2B in a sheet transport path, and a pair of discharge rollers 17 located downstream of the fixer 16. On the photoreceptor drums 1B, 1Y, 1C, and 1M, latent images are formed and developed with black, yellow, cyan, and magenta toners.
The image forming apparatus A further includes a sheet feeder 10 having a sheet cassette 11 and a feed roller 12, located at a bottom portion thereof, transport rollers 13, a pair of registration rollers 14, and a controller 56.
The toner images on the photoreceptor drums 1B, 1Y, 1C, and 1M are transferred and superimposed as a full color image on a sheet transported on the transfer and transport belt 3A. The full color image is fixed on the sheet by the fixer 16 and discharged from the image forming apparatus A1 with a pair of discharge rollers 17. Thus, the image forming apparatus A1 applies a direct transfer belt method.
As can be appreciated by those skilled in the art, although the transferer is a transfer roller in the description above, alternatively, other types of transferees, such as a transfer brush, may be used. Further, the present invention may be applied to a tandem image forming apparatus without an intermediate transfer belt or a transfer and transport belt.
Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the disclosure of this patent specification may be practiced otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-314800 | Nov 2006 | JP | national |
| 2007-177707 | Jul 2007 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 7274897 | Katoh | Sep 2007 | B2 |
| 20040234287 | Nishida et al. | Nov 2004 | A1 |
| 20060067744 | Shin et al. | Mar 2006 | A1 |
| 20060067745 | Yamada et al. | Mar 2006 | A1 |
| 20060210307 | Katoh et al. | Sep 2006 | A1 |
| 20060210324 | Kuma et al. | Sep 2006 | A1 |
| 20060284958 | Saeki et al. | Dec 2006 | A1 |
| 20070098472 | Saeki et al. | May 2007 | A1 |
| 20070127947 | Kuma et al. | Jun 2007 | A1 |
| 20070127955 | Katoh et al. | Jun 2007 | A1 |
| Number | Date | Country |
|---|---|---|
| 2002-40753 | Feb 2002 | JP |
| 2005-266269 | Sep 2005 | JP |
| 2008122596 | May 2008 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20080175619 A1 | Jul 2008 | US |
