Patent Grant
7184679
This invention relates in general to a fuser assembly for an electrographic reproduction apparatus, and more particularly to a receiver member speed control through the fuser assembly.
In typical commercial reproduction apparatus (electrostatographic copier/duplicators, printers, or the like), a latent image charge pattern is formed on a uniformly charged charge-retentive or photoconductive member having dielectric characteristics (hereinafter referred to as the dielectric support member). Pigmented marking particles are attracted to the latent image charge pattern to develop such image on the dielectric support member. A receiver member, such as a sheet of paper, transparency or other medium, is then brought into contact with the dielectric support member, and an electric field applied to transfer the marking particle developed image to the receiver member from the dielectric support member. After transfer, the receiver member bearing the transferred image is transported away from the dielectric support member, and the image is fixed (fused) to the receiver member by application of heat and pressure to form a permanent reproduction thereon.
One type of fuser assembly for typical reproduction apparatus includes at least one heated roller, having an aluminum core and an elastomeric cover layer, and at least one pressure roller in nip relation with the heated roller. The fuser assembly rollers are rotated to transport a receiver member, bearing a marking particle image, through the nip between the rollers. The pigmented marking particles of the transferred image on the surface of the receiver member soften and become tacky in the heat. Under the pressure, the softened tacky marking particles attach to each other and are partially imbibed into the interstices of the fibers at the surface of the receiver member. Accordingly, upon cooling, the marking particle image is permanently fixed to the receiver member.
In the fuser assembly, at least one of the fuser and pressure rollers is compliant. Further, one of the fuser and pressure rollers, is driven by a driving motor (designated as the driving roller), and the other roller is driven by the friction in the nip (designated the driven roller). In the nip region, the compliant, uncompressible materials on the fuser and/or the pressure rollers are stressed and strained under pressure. This causes a phenomenon called “overdrive,” in which a segment along a linear element on the compliant surface of the roller in the nip region goes faster than a segment along a linear element on the free surface of the roller. The thicker the compliant, uncompressible material on a roller, the more the overdrive. The overdrive causes the receiver member being transported in the nip to go faster than the roller free surface speed.
Once the thickness of the compliant, uncompressible materials on the fuser and pressure rollers are determined, the factor that can affect the overdrive the most is the pressure applied to the fuser/pressure roller nip, or equivalently the nip width. In the process of fixing the toner image permanently to the receiver, it is sometime necessary to adjust nip width for different receiver member thickness, different image gloss level, and/or compensating temperature variation. This can cause varying receiver member speed through the fuser assembly. Because the reproduction apparatus process speed is usually fixed, this varying receiver member speed through the fuser assembly may cause speed mismatch with the surrounding reproduction apparatus sub-systems and components. The resultant speed mismatch problem may include pulling/pushing of the receiver member, distortion to the image and/or the receiver member, triggering false jam detection, or actually causing a jam. Therefore, there is a need to compensate for this speed variation at fusing station.
It is the purpose of this invention to compensate for receiver member speed variation through a reproduction apparatus fuser assembly due to overdrive characteristics of the driving roller of the fuser assembly, obtained experimentally or analytically, by adjusting the driving motor speed based on the load (or pressure, nip width). A speed control mechanism is provided for a reproduction apparatus including a fuser assembly having pressure applying members in nip relation to apply pressure to a receiver member bearing a marking particle image to fuse such marking particle image to such receiver member transported through the fuser assembly. The speed control mechanism has an input device for storing parameters required for fusing particular types of receiver members under various desired conditions, and a device for determining fuser control parameters, including overdrive effect, based on information from the input device and selection of a particular receiver member type and certain conditions. A fuser assembly controller then sets fusing parameters based on the determination by the determining device, and adjusts the transport speed of a receiver member through the fuser assembly to compensate for the determined overdrive effect.
In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which:
An exemplary reproduction apparatus, designated generally by the numeral 10, is schematically shown in
After transfer, a receiver member bearing the transferred composite image is transported by belt 24 away from the last printing module to a fuser assembly 26 where the composite image is fixed (fused) to the receiver member by application of heat and pressure to form a permanent reproduction thereon. The speed of the fuser roller is controlled by a drive motor 64. A main reproduction apparatus controller 60 receives data from an input data storage device 60a. The input data includes parameters required for fusing particular receiver members under various conditions, and provides such parameters based on the particular receiver member, for transmission to a fuser assembly controller 62. The parameters can include nip pressure, nip width, temperature, and transport speed, which may vary for each receiver member type and desired operating condition such as the desired gloss for example. The fuser assembly controller 62 can then get, or calculate, the load or nip required for proper fusing. The controllers 60 and 62 may be any suitable well-known microprocessor-based devices capable of processing input data, determining related operating parameters, and setting the required fuser assembly control based on the determined parameters. Of course, the controllers 60 and 62 could, alternatively, be combined into a single controller. Thereafter, the print is transported to a remote collection location by any suitable transport mechanism 28.
The fuser assembly 26 for the reproduction apparatus 10 is best shown in
Generally the fuser roller 30 has a metal core 38, a compliant uncompressible base cushion 40, and a thin release topcoat 42. The base cushion 40 is formed of an elastomeric material. A thicker base cushion makes the geometry in the nip area more favorable for the receiver member R to be released from the fuser roller 30, but makes the heat more difficult to transfer from the metal core 38 to the outer surface of the topcoat 42.
As noted above, because of the nature of the compliant, uncompressible materials of the fuser roller 30, in the nip region, the fuser and/or the pressure rollers are stressed and strained under pressure. As a result, a receiver member passing through the nip is subject to overdrive due to the fact that a segment along a linear element on the compliant surface of the roller in the nip region goes faster than a segment along a linear element on the free surface of the roller. The thicker the compliant, uncompressible material on a roller, the more the overdrive effect. The overdrive effect causes the receiver member being transported through the nip to go faster than the roller free surface speed.
Referring to
Once a previous receiver member has passed through the fuser assembly roller nip, and the fuser roller 30 and the pressure roller 32 are in direct nip contact (that is, are within the inter-frame between the previous receiver member and a subsequent receiver member (step 205)), the fuser assembly controller 62 adjusts the speed of the fuser roller drive motor 64 (step 206) by decreasing the motor speed by an appropriate percentage, such as determined from the graphs of
As a result of the receiver member speed compensation control according to this invention, receiver members are transported smoothly through the fuser assembly. Reliability of the receiver member transport is markedly improved by substantially reducing the speed mismatch problem so that pulling/pushing of the receiver member is prevented, as is distortion to the image and/or the receiver member. Furthermore, there is no triggering of false jam detection, or actual jams.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
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| Number | Date | Country | |
|---|---|---|---|
| 20060245776 A1 | Nov 2006 | US |
