Fusing roller with an elastic layer of low hardness and method of manufacturing the same, fusing unit employing the fusing roller, and image forming apparatus employing the fusing unit

A fusing roller which is heated by a heat source, includes: a core member; a first primer which is formed on a circumference of the core member; an elastic layer which is formed on a circumference of the first primer, and adhered on the circumference of the core member by the first primer; and a basic coating layer which is disposed between the core member and the first primer, and chemically combined with the first primer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Korean Patent Application No. 10-2007-0004351, filed on Jan. 15, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Apparatuses and methods consistent with the present general inventive concept relate to a fusing roller which heats non-fused image transferred onto a printing medium and a method of manufacturing the same, a fusing unit employing the fusing roller and an image forming apparatus employing the fusing unit, and more particularly, to a fusing roller which is provided to prevent wrap jam, to secure heat necessary to fuse during a high-speed printing and a stable durability and a method of manufacturing the same, a fusing unit employing the fusing roller and an image forming apparatus employing the fusing unit.

2. Description of the Related Art

In general, an electrophotographic image forming apparatus scans a beam onto a photosensitive body electrified to a predetermined electric potential to form an electrostatic latent image, and develops the image with a predetermined color toner and transfers and fuses the same onto a printing medium to print an image thereon. The electrophotographic image forming apparatus is provided with a fusing unit along a printing path to fuse the transferred image onto the printing medium.

FIG. 1is a schematic view illustrating a conventional lamp heating type fusing unit, andFIG. 2is a schematic sectional view illustrating a layer configuration of a fusing roller inFIG. 1.

Referring to the figures, the conventional fusing unit is provided to fuse a non-fused toner image T formed on a printing medium M. The conventional fusing unit comprises a fusing roller10in which a thermal lamp1is built therein, a pressing roller20which is disposed to face the fusing roller10and is elastically biased to press toward the fusing roller10by an elastic member5to form a fusing nip, and a temperature sensor7which senses temperature of a surface of the fusing roller10.

The fusing roller10comprises a first core pipe11which is provided of a metal material. A first elastic layer15and a first release-layer19(FIG. 2) are sequentially formed on the surface layer of the first core member11and jointed adhesively all together by primers13and17(FIG. 2).

Accordingly, the first core pipe11is heated by the thermal lamp1, and the first elastic layer15is heated by a thermal conduction of the heated pipe11to rise to a predetermined fusing temperature where it is maintained.

The temperature sensor7measures temperature of a surface of the first elastic layer15in and out of contact with the fusing roller10. Accordingly, a power supplied for the thermal lamp1can be controlled on the basis of the measured temperature value.

Accordingly, if the printing medium M on which the non-fused toner image T is formed is transferred to the fusing unit, the toner image T is heated and pressurized by passing through the fusing nip provided between the fusing roller10and the pressing roller20, to be fused onto the printing medium M, and thus the fusing process is completed.

In the color electrophotographic image forming apparatus employing the fusing unit, a first elastic layer is required to have a thin thickness in order to improve warm-up efficiency in forming the fusing roller. Meanwhile, if the thickness of the first elastic layer is thin, a fusing property may be degraded due to reduction of the width of the fusing nip.

Therefore, a hardness of rubber which forms the first elastic layer must be in a low state in order to reduce a warm-up time, to secure fixedness, and to satisfy a margin for preventing wrap jam.

Meanwhile, as described above, if the hardness of the first elastic layer is low, the first elastic layer may be easily exfoliated from a first core pipe. The exfoliation phenomenon is deepened as the fusing temperature and pressure become high.

The exfoliation phenomenon is mainly caused by a chemical property of a low hardness rubber. This is because the low hardness rubber has a small number of cross-linked points, and accordingly is not easily jointed with material other than a high hardness rubber having a lot of cross-linked points. In particular, if the surface is relatively stabilized and does not have a reaction radical, a chemical reaction necessary for coupling tends to be insufficient or weak.

Also, the exfoliation phenomenon may be progressed to occur at a weak portion by a non-uniform coupling on a coupling surface between an elastic layer of rubber material having relatively high temperature and a high deformation and a metal core pipe.

Accordingly, the first elastic layer is exfoliated from the first core pipe under a fusing circumstance of a high temperature and high pressure, and thus durability of the fusing roller may be degraded.

SUMMARY OF THE INVENTION

The present general inventive concept provides a fusing roller which can allow an elastic layer to have a low hardness and prevent an exfoliation of the elastic layer, and a method of manufacturing the same, and a fusing unit and an image forming apparatus employing the same.

The foregoing and/or other aspects and utilities of the present general inventive concept can be achieved by providing a fusing roller which is heated by a heat source, comprising: a core member; a first primer which is formed on a circumference of the core member; an elastic layer which is formed on a circumference of the first primer, and adhered on the circumference of the core member by the first primer; and a basic coating layer which is disposed between the core member and the first primer, and chemically combined with the first primer.

The foregoing and/or other aspects and utilities of the present general inventive concept can also be achieved by providing a method of manufacturing a fusing roller comprising a core member and an elastic layer which is formed on a circumference of the core member, the method comprising: forming a basic coating layer by coating a basic substance on the circumference of the core member; chemically combining the basic coating layer with a first primer by spreading a first primer on the basic coating layer; and forming the elastic layer on a circumference of the first primer.

The foregoing and/or other aspects and utilities of the present general inventive concept can also be achieved by providing a fusing unit which is provided on a printing path, and fuses an image transferred on a printing medium, the fusing unit comprising: a fusing roller; a pressing roller which is disposed to face the fusing roller, and cooperates to pressurize the printing medium with the fusing roller; and an elastic member which elastically biases to press the pressing roller so as to form a predetermined fusing nip between the fusing roller and the pressing roller.

The foregoing and/or other aspects and utilities of the present general inventive concept can also be achieved by providing an image forming apparatus, comprising: at least one photosensitive body; at least one light scanning unit which scans a beam onto the photosensitive body and forms an electrostatic latent image; at least one developing unit which develops a toner image with respect to the electrostatic latent image formed on the photosensitive body; a transferring unit which transfers the toner image formed by the developing unit on a printing medium; and a fusing unit which fuses the non-fused toner image transferred on the printing medium.

The foregoing and/or other aspects and utilities of the present general inventive concept can also be achieved by providing a method of manufacturing a fusing roller, the method including preparing a surface of a core member to be chemically combined with a primer to be applied thereon, chemically combining the surface of the core member with a first primer by spreading the first primer on the core member, and forming the elastic layer on a circumference of the first primer.

The preparing of a surface of a core member may include coating a basic substance on the circumference of the core member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below so as to understand more apparently the present general inventive concept by referring to the figures.

As illustrated inFIG. 3, a fusing roller30according to the exemplary embodiment of the present invention is heated by a heat source. The fusing roller30comprises a core member31, a basic coating layer33, a first primer35and an elastic layer37which are sequentially formed on a circumference of the core member31.

The core member31is to maintain the shape of the fusing roller30according to the present general inventive concept. The core member31can be provided of metal, such as aluminum, having a good rigidity and thermal conductivity. Here, the surface of the core member31may be processed with sand blast so that the basic coating layer33can be coated on the external surface of the core member31.

The first primer35is used to join the elastic layer37with the core member31, and comprises a high polymer.

As described above, the elastic layer37is provided of a low hardness rubber so as to reduce a warm-up time, to secure fixedness and to satisfy a margin for preventing wrap jam at the same time. For example, if the hardness value of the elastic layer37is set as H, the H satisfies a condition of the following formula 1.
2°≦H≦10°  [conditional expression 1]

Here, the hardness value H denotes a value according to the standard JIS-A.

Also, the elastic layer37may comprise silicon rubber or fluorine rubber in consideration of setting of width of the fusing nip and fusing temperature formed in a space with a pressing roller (refer to120inFIG. 10) if the fusing unit, which will be described later, employs the fusing roller30according to the present general inventive concept. Here, for example, poly dimethyl silicon rubber, metal vinyl silicon rubber, metal phenyl silicon rubber, fluorine silicon rubber and the like are employed for the silicon rubber.

Meanwhile, as described above, an exfoliating problem of the elastic layer37can be solved by further comprising a basic coating layer33between the core member31and the first primer35, and chemically combining the basic coating layer33with the first primer35.

The basic coating layer33prevents the elastic layer37from being exfoliated from the core member31by a chemical combination with the first primer35.

For this purpose, the basic coating layer33is formed by basic-coating processing on the external surface of the core member31, and forms a predetermined functional group. That is, the basic coating layer33comprises a hydroxyl group (—OH) or a carboxyl group (—COOH), and dehydrating-reacts with the first primer35to be chemically coupled with the first primer35.

Here, if the hydroxyl group (—OH) is included in forming the basic coating layer33, the basic coating layer33may be provided of hydroxyl group chemicals comprising phosphoric acid manganese [Mn5H2(PO4)4.4H2O/FeHPO4.2H2O], phosphoric acid zinc [Zn3(PO4)2.4H2O/FeHPO4.2H2O] and phosphoric acid iron [FeHPO4.2H2O/γFe2O3].

As described above, the cross-linked point can be increased between the core member31and the elastic layer37as in the case of the high-hardness elastic layer by chemically coupling the basic coating layer33with the first primer35. Accordingly, the elastic layer37can be prevented from being exfoliated, and can be uniformly formed via the first primer35. Here, a detail of the chemical coupling between the functional group of the basic coating layer33and the functional group of the first primer35will be described later.

Also, the fusing roller30according to the exemplary embodiment ofFIG. 3may further comprise a second primer39and a release-layer41sequentially formed on the elastic layer37.

The second primer39is disposed between the elastic layer37and the release-layer41to adhere the release-layer41on a circumference of the elastic layer37. The release-layer41prevents a heated medium (not illustrates) from being adhered on the circumference of the elastic layer37. Accordingly, a printing medium (see M inFIG. 10) is prevented from being adhered to the fusing roller30if the fusing roller30is employed in the fusing unit of the image forming apparatus, thereby preventing a wrap jam.

Referring toFIG. 4, a fusing roller50according to another exemplary embodiment of the present general inventive concept is heated by a heat source, and comprises sequentially a core member51, a plating layer53formed on the circumference of the core member51, a basic coating layer55, a first primer57and an elastic layer59.

In the exemplary embodiment ofFIG. 4, the description of each structure of the core member51, the basic coating layer55, the first primer57and the elastic layer59will be omitted so as to avoid a repeated explanation as it practically performs the same function as the structure having the same member name of the fusing roller (see30inFIG. 3) according to the exemplary ofFIG. 3embodiment. Meanwhile, the fusing roller50according to this exemplary embodiment is distinguished from the fusing roller (see30inFIG. 3) according to the previous exemplary embodiment in that it further comprises the plating layer53between the core member51and the basic coating layer55.

The plating layer53prevents the core member51from being corroded through the above-described basic coating processing if the core member51is provided of metal having a weak corrosion. Here, the formation of the plating layer53can be performed by plating processing such as electroplating, vacuum depositing, vacuum alloying, ion plating, melted plating, cathode sputtering, and vapor plating.

As described above, if the plating layer53is formed on the core member51, the core member51can be prevented from being corroded by forming the basic coating layer55on the circumference of the core member51.

Here, the surface of the core member51may be processed with sand blast so that the plating layer53can be uniformly coated.

Also, the surface of the plating layer53may be processed with sand blast so that the basic coating layer55can be uniformly coated on the plating layer53.

Also, the fusing roller50according to this exemplary embodiment may further comprise a second primer61and a release-layer63, which are sequentially formed on the elastic layer59. The description of the structure and the function of the second primer61and the release-layer63will be omitted as they are the same as the configuration having the same member name according to the previous exemplary embodiment.

Hereinafter, a method of manufacturing the fusing roller according to several exemplary embodiments of the present general inventive concept will be described in detail while referring toFIGS. 5 to 7.

FIGS. 5 to 7are schematic block diagrams illustrating manufacturing processes of the fusing rollers according to the previous exemplary embodiments ofFIGS. 3 and 4.

The manufacturing method of the fusing roller according to the exemplary embodiment ofFIG. 3is used for manufacturing the fusing roller having the configuration illustrated inFIG. 3.

Referring toFIGS. 3 and 5, the manufacturing method of the fusing roller according to the exemplary embodiment ofFIG. 3comprises stages carried out sequentially on the circumference of the core member31, the stages including: a stage S13on which the basic coating layer33is formed, a stage S15on which the first primer35is spread, and a stage S17on which the elastic layer37is formed.

In the stage S13a basic coating layer is formed by coating a basic substance comprising a hydroxyl group (OH—) or a carboxyl group (COOH—) on the circumference of the core member31. Here, a stage S11on which the surface of the core member31is processed with sand blast may be further performed before the stage S13so that the basic coating layer33can be uniformly coated on the surface of the core member31.

In the stage S15of spreading the first primer35, the basic coating layer33is chemically combined with the first primer35, and the elastic layer37can be prevented from exfoliating even though the elastic layer37has a low hardness.

Also, a stage on which the second primer39is spread on the elastic layer37, and a stage on which a release-layer41can be formed on an external part of the second primer39may be further performed so that a heating object does not adhere on the external surface of the elastic layer37.

A manufacturing method of the fusing roller according to another exemplary embodiment of the present general inventive concept is used to manufacture the fusing roller having the configuration illustrated inFIG. 4. Referring toFIGS. 4 and 6, the manufacturing method of the fusing roller according to this exemplary embodiment comprises stages carried out sequentially on the circumference of the core member51, the stages including: a stage S21on which the plating layer53is formed, a stage S25on which the basic coating layer55is formed, a stage S27on which the first primer57is spread, and a stage S29on which the elastic layer59is formed on.

The plating layer53is formed to prevent the core member51from being corroded by a chemical reaction with the basic coating layer55. The plating layer53is formed on the circumference of the core member51through the stage S21. Here, the formation of the plating layer53can be performed by a plate processing such as electroplating, vacuum depositing, vacuum alloying, ion plating, melted plating, cathode sputtering, and vapor plating.

At the forming stage S25the basic coating layer55is formed by coating a basic substance comprising a hydroxyl group (OH—) or a carboxyl group (COOH—) on the circumference of the core member51. Here, a stage S23on which the surface of the plating layer53is processed with sand blast may be further preformed before the stage S25so that the basic coating layer55can be uniformly coated on the surface of the plating layer53.

The stage S27of the first primer57chemically combines the basic coating layer55with the first primer57, and the elastic layer59can be prevented from being exfoliated by chemical combination between the basic substance and the first primer57even though the elastic layer59is in a low hardness state.

Also, a stage on which the second primer61is spreaded on the elastic layer59, and a stage on which a release-layer63can be formed at an external part of the second primer61may be further performed so that a heating object is not adhered on the external surface of the elastic layer59.

A manufacturing method of the fusing roller according to another exemplary embodiment of the present general inventive concept is used to manufacture the fusing roller having the configuration illustrated inFIG. 4. Referring toFIGS. 4 and 7, the manufacturing method of the fusing roller according to this exemplary embodiment comprises stages carried out sequentially on the circumference of the core member51, the staging including: a stage S33on which the plating layer53is formed, a stage S35on which the basic coating layer55is formed, a stage S37on which the first primer57is spread, and a stage S39on which the elastic layer59is formed.

Also, a stage S31on which the surface of the plating layer53is processed with sand blast may be further performed before the stage S33so that the basic coating layer55can be uniformly coated on the surface of the core member51. In addition, a stage on which the surface of the plating layer53is processed with sand blast may be further performed before the stage S35.

The detailed description of the other processes will be omitted as they are similar to the manufacturing process of the fusing roller according to the previous exemplary embodiment.

Hereinafter, chemical coupling between the basic coating layers33and55and the first primers35and57which form the fusing roller according to the above-described exemplary embodiments will be described.

Referring toFIGS. 8A and 8B, the first primers35and57which are formed of high polymers comprise a hydroxyl group (OH—). Also, the basic coating layers33and55which are coated on the surface of the first primers35and57comprise a hydroxyl group (OH—). Accordingly, as Illustrated in an area A, each of the hydroxyl groups of the basic coating layers33and55and the first primers35and57forms a functional group.

Hereinafter, the functional group of the basic coating layers33and55hydrated-reacts with the functional group of the first primers35and57, and H2O gets out of the group. Also, as illustrated in an area B, the basic coating layers33and55, and the first primers35and57are chemically combined with each other. By the chemical coupling, the first primers35and57are adhered to the core members31and51, respectively, and elastic layers37and59having a low hardness are formed by the adhered first primers35and57, thereby complementing a weak point for coupling.

As illustrated inFIGS. 9A and 9B, the first primers35and57which are formed of high polymers comprise a hydroxyl group (OH—). Meanwhile, the basic coating layers33and55comprise a carboxyl group (COOH—).

Accordingly, as illustrated in an area C, the carboxyl group of the basic coating layers33and55and the hydroxyl group of the first primers35and57form a functional group.

Accordingly, the functional group of the basic coating layers33and55hydrated-reacts with the functional group of the first primers35and57, and H2O gets out of the group. Also, as illustrated in an area D, the basic coating layers33and55and the first primers35and57are chemically combined with each other. By the chemical coupling, the first primers35and57are adhered to the core members31and51, respectively, and elastic layers37and59having a low hardness are formed through the first primers35and57, thereby removing a weak point for coupling.

As illustrated inFIG. 10, the fusing unit according to this exemplary embodiment is provided on a printing path of an image forming apparatus to fuse an image T transferred on a printing medium M. The fusing unit comprises a fusing roller in which a thermal lamp101is built, a pressing roller120which is disposed to face the fusing roller110and is elastically biased to press toward the fusing roller110by an elastic member105to form a fusing nip, and a temperature sensor107which senses the surface temperature of the fusing roller110.

The fusing roller110comprises a first core member111which is provided of a metal material, a basic coating layer112, a first primer113, a first elastic layer115, a second primer117and a first hetero layer119which are sequentially formed on the surface of the first core member111. Therefore, the first core member111is heated by the thermal lamp101, and the first elastic layer115is heated by the thermal conduction to rise to a predetermined fusing temperature and be maintained.

Here, the detail description of the fusing roller110will be omitted as it has a similar configuration as the fusing roller110according to the exemplary embodiments of the present general inventive concept described with reference toFIGS. 3 and 4.

The temperature sensor107measures the surface temperature of the first elastic layer115in and out of contact with the fusing roller110. Accordingly, a power supplied for the thermal lamp101can be controlled on the basis of the measured surface temperature value measured in the temperature sensor107.

The pressing roller120comprises a second core member121which can be provided of metal, a second elastic layer125and a second release-layer (not illustrated) which are sequentially provided on the surface of the second core member121.

Accordingly, if the printing medium M on which a non-fused toner image T is formed is fed to the fusing unit, the toner image T is heated and pressurized through the fusing nip provided between the rotating fusing roller110and the pressing roller120to be fused onto the printing medium M, and thus the fusion is completed.

As illustrated inFIG. 11, the image forming apparatus according to an exemplary embodiment comprises a plurality of photosensitive bodies210, a plurality of light scanning units220which scan a beam onto each the photosensitive body210to form each electrostatic latent image thereon, a plurality of developing unit230which develop toner image with respect to the electrostatic latent image formed on each photosensitive body210, a transferring unit240which transfers the toner image formed by each light scanning unit230onto a printing medium M, and a fusing unit250which fuses the non-fused toner image transferred onto the printing medium M.

Here,FIG. 11illustrates a tandem-type color image forming apparatus as an example. The photosensitive body210, the laser scanning unit220and the developing unit230are provided in plural for each of the colors along with the feeding path of the printing medium M.

The transferring unit240is disposed to face the plurality of photosensitive bodies210. When the printing medium M is passed through the feeding path intervened therebetween, the transferring unit240transfers the toner image formed by the light scanning unit230on the passed printing medium M. For performing this function, the transferring unit240comprises a transferring belt241which is disposed to face the plurality of photosensitive bodies210.

The fusing unit250comprises a fusing roller251in which a thermal lamp251ais built, a pressing roller255which cooperates to pressurize the printing medium M on which the non-fused toner image is formed with the fusing roller251, and an elastic member257which elastically biases to press the pressing roller255in a direction of the fusing roller251. Accordingly, the fusing roller251heats its surface by the heat generated in the thermal lamp251a, and fuses the non-fused toner image T transferred onto the printing medium M by pressure of the pressing roller255. Here, the detail description of the configuration and operating principle of the fusing unit250will be omitted as it is similar to that of the fusing unit according to the above-described exemplary embodiments.

As described above, the fusing roller and the fusing unit employing the same according to the various embodiments have effects as follows. The fusing roller and the fusing unit employing the same allow an elastic layer to have a low hardness, thereby reducing a warm-up time, securing a good fixedness, and satisfying a margin for preventing wrap jam. Also, a cross-linked point increases through chemical coupling by dehydrating-reaction between a basic coating layer and a primer, thereby preventing exfoliation of an elastic layer even under a fusing condition in high temperature and pressure. Accordingly, durability of the fusing roller can be prevented from depreciating, and thereby increasing durability of the fusing roller and the fusing unit employing the same.

Also, in the methods of manufacturing the fusing roller, corrosion of a core member caused in forming a basic coating layer on the fusing roller is prevented, and a plating layer and a basic coating layer are uniformly adhered on the surface of the core member through a sand blast processing, thereby improving durability of the fusing roller.

Furthermore, the image forming apparatus employing the fusing unit having the above-described configuration according to the present general inventive concept allow an elastic layer of the fusing roller to have a low hardness, thereby reducing a warm-up time, and preventing a fusing inferiority and wrap jam. Also, durability of fusing unit is improved, thereby enhancing the reliability for the image forming apparatus.