JP3520742B2 - Fixing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-air fixing type fixing device used in an image forming apparatus using a fusible recording material such as toner.

[0002]

2. Description of the Related Art In recent years, as represented by a laser printer, the performance of an electrophotographic (toner) image forming apparatus capable of forming a clear image with excellent resolution has been remarkably improved. Further, further improvement in the fixing process is desired in order to improve the final print quality of the image forming apparatus.

A fixing device used in the fixing process of such an image forming apparatus will be described below.

FIG. 6 is a schematic diagram showing the structure of a conventional contact-type fixing device, and FIGS. 7 to 10 are schematic diagrams showing the printing surface fixed by the conventional contact-type fixing device.
FIG. 11 is a schematic view showing a case where a conventional contact type fixing device is used in a fixing process of an orthogonal transfer type image forming apparatus.

As shown in FIG. 6, the conventional contact-type fixing device 1 employs a roller fixing method. In this roller fixing method, when a print sheet 3 as an example of a recording medium onto which an image formed by a toner 2 as an example of a recording material has been transferred is conveyed, the heating roller 4 and the pressure roller 5 move. The printing paper 3 is sandwiched and the toner 2 on the surface is heated and melted and fixed on the printing paper 3.

However, in the contact type fixing device 1 as described above, as shown in FIG. 7, the particles of the toner 2 are crushed more than necessary from the state shown by the broken line to the state shown by the solid line, so that they are crushed. The particles of the toner 2 spread too much, resulting in poor resolution and poor print quality in the fixing step. Particularly in the case of a color image, as shown in FIG. 8, four colors of cyan, magenta, yellow, and black are superimposed to express colors, and therefore the color of toner 2 is increased by the amount corresponding to the increase in the thickness of the toner image. Since the layers are apt to be displaced and the color displacement is generated, the print quality is much lower than that in the case of a monochrome image.

The toner 2 melted by touching the heating roller 4 may adhere to the heating roller 4 side. In that case, as shown in FIG. 9, the toner 2 adhered to the heating roller 4 side is printed paper. 3 may be transferred to a white background portion of the sheet 3 to become stains 6, and as shown in FIG. 10, a trailing 7 may occur in a portion on the downstream side with respect to the conveyance direction of the print sheet 3. In either case, it is unavoidable that the print quality deteriorates in the fixing process.

In addition, when the contact type fixing device 1 is used in the fixing process of the orthogonal transfer type image forming apparatus as shown in FIG. 11, the transfer to the print sheet 3 is performed by the orthogonal transfer type. Since the printing paper 3 is carried in the direction orthogonal to the carrying direction, the printing paper 3 is carried to the fixing device 1 intermittently rather than continuously. Therefore, although the printing paper 3 is good while being conveyed to the fixing device 1, the toner 2 in a portion in contact with the heating roller 4 is overheated while the conveyance is stopped, so that uneven fixing occurs.

For these reasons, in the fixing device 1 of the contact type in which the printing paper 3 is brought into contact with and heated, it is unavoidable that the printing quality is deteriorated in the fixing process. Therefore,
As disclosed in Japanese Patent Application Laid-Open No. 53-92137, a non-contact method of heating without contacting the printing paper 3 is employed to prevent deterioration of printing quality in the fixing step.

FIG. 12 is a schematic view showing the structure of a conventional non-contact type fixing device. As shown in FIG. 12, the conventional non-contact fixing device 8 adopts the hot air fixing method. In this hot-air fixing method, when a print sheet 3 as an example of a recording medium onto which an image formed by toner 2 as an example of a recording material has been transferred is conveyed, hot air generated by hot-air means 9 is printed. The toner 2 on the surface of the printing paper 3 is heated and melted by being sprayed onto the paper 3, and is fixed on the printing paper 3.

Therefore, various problems caused by the contact method as described with reference to FIGS. 7 to 11 are solved, and deterioration of print quality in the fixing step is prevented.

[0012]

However, in the conventional non-contact type fixing device 8 as described above, as shown in FIG.
As shown in FIG. 4, the hot air generating method by the hot air means 9 heats the heating element 10 and sends the air flow created by the blowing means 12 into the through hole 11 provided in the heating element 10, and the air flow is changed as indicated by the arrow. When passing through the through-hole 11, heat is taken from the periphery of the through-hole 11 and turned into hot air. for that reason,
The amount of heat taken from the heating element 10 varies depending on how much the surface of the heating element 10 is touched during the time when the airflow flows into the heating element 10 until it flows out. That is, the heating element 10
Since the heat exchange from the air flow to the air flow is being performed, it is better that the surface area of contact between the air flow and the heating element 10 is large. However, the through hole 11 of the heating element 10 is
Since there is a direct passage from the upper part to the lower part of 0, the surface area of the heating element 10 in contact with the air flow is small, and there is a problem that the heat exchange efficiency from the heating element 10 to the air flow is poor.

In addition, the hot air that has passed through the through holes 11 of the heating element 10 melts the toner 2 on the surface of the printing paper 3 and then flows out to the upstream side or the downstream side of the heating element 10 as indicated by the arrow. However, there is a problem that the hot air flowing into the upstream side of the heating element 10 may cause deterioration of the photoconductor or may melt the toner 2 on the photoconductor before transfer onto the printing paper 3.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a fixing device provided with hot air means having improved heat exchange efficiency.

[0015]

In order to solve this problem, the present invention is directed to a support member for supporting a recording medium to which a fusible recording material is attached, and a surface of the supporting member facing the recording medium. A heat transfer member having a high heat conductivity, which comprises a plurality of through holes provided with a plurality of through holes and a plurality of layers sandwiching an air layer therebetween; The heat energy applying means applies heat energy to the heat member, and the air blowing means sends air to the through holes of the heat transfer member.

According to the present invention, it is possible to provide the fixing device provided with the hot air means having improved heat exchange efficiency.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a supporting member for supporting a recording medium having a fusible recording material adhered thereto and a surface of the supporting member for supporting the recording medium are provided so as to face each other. And a hot air means for blowing hot air to the recording medium, the hot air means having a plurality of through-holes and a heat transfer member having a high thermal conductivity consisting of a plurality of layers of plates sandwiching an air layer therebetween,
It is composed of a heat energy applying means for giving heat energy to the heat transfer member and a blower means for sending air to the through hole of the heat transfer member, and the heat transfer is performed by a plurality of layers of plates sandwiching an air layer therebetween. Since the member is configured, not only the through hole but also both surfaces of the plate provided with the through hole can be brought into contact with air, and the heat of the heat transfer member can be efficiently transmitted to the air. It has the effect that the air warmed in the layer of (3) can be blown to the recording medium through the through holes.

According to a second aspect of the present invention, in the invention according to the first aspect, the heat transfer member is formed by bending one plate into a plurality of layers, and the plurality of layers are formed by one plate. It has the effect that it can be configured.

According to a third aspect of the present invention, in the first aspect of the invention, the heat energy applying means is a ceramic heater, and the heat energy applying means can be made thin. Have.

According to a fourth aspect of the present invention, in the invention according to the first aspect, the blower means is a blower fan, and it is possible to feed a wind having a sufficient wind pressure to the heat transfer member. Have.

The invention according to claim 5 of the present invention is the invention according to any one of claims 1, 2, 3 and 4, wherein
The recording material is toner and has the same effect as that of the first aspect.

According to a sixth aspect of the present invention, in the invention according to any one of the first, second, third, fourth and fifth aspects, the hot air means is provided upstream of the hot air means in the conveying direction of the recording medium. It is provided with a cool air unit that blows a lower temperature air to the recording medium, and blows hot air to the toner adhesion process of the toner to the recording medium by forming an air curtain by the air from the air blowing unit to block it. It has the effect of preventing the melting of the toner during the toner adhesion process and the like, and the deterioration of the photoreceptor and the like due to heat.

The embodiments of the present invention will be described below. The same parts as those of the conventional example are designated by the same reference numerals.

(Embodiment 1) The outline of one embodiment of the present invention is that the contact area between the air flow sent out by the blowing means of the hot air means and the heating element is narrow in the conventional example of the non-contact method. This is because the contact area between the air flow and the heating element (the heat energy applying means and the heat transfer member) is widened to improve the heat exchange efficiency from the heating element to the air flow.

In addition, cold air means is provided upstream of the hot air means so that the hot air generated by the hot air means does not flow into the upstream side of the hot air means and damage the photosensitive member and the like, and the air curtain is formed by the cold air produced by the cold air means. Is formed so as to prevent the hot air from flowing into the upstream side of the hot air means.

The details of one embodiment of the present invention will be described below with reference to FIG.
-It demonstrates, referring FIG. FIG. 1 is a schematic view showing the structure of a fixing device according to an embodiment of the present invention.
FIG. 4 is a schematic diagram showing the flow of air flow that has flowed into the heat transfer member of the fixing device according to the embodiment of the present invention. FIG. 3 is a schematic diagram showing the structure of the fixing device according to the embodiment of the present invention, and FIGS. 4 to 5 are schematic diagrams showing the structure of the cold air means of the fixing device according to the embodiment of the present invention.

As shown in FIG. 1, the fixing device 21 of the present invention.
Uses a hot air fixing method. In this hot-air fixing method, an image formed by toner 2 as an example of a recording material has been transferred, and printing paper 3 as an example of a recording medium has been transferred.
When the OHP (including the OHP paper) is conveyed, the printing paper 3 is supported by the hot air from the hot air means 22 on the support member 23.
The toner 2 on the surface of the printing paper 3 is heated and melted and fixed on the printing paper 3.

The hot air means 22 is roughly classified into a heat transfer member 24, a heat energy applying means 25 for applying heat energy to the heat transfer member 24, and a blowing means 27 for sending air to the through holes 26 of the heat transfer member 24. It is configured.

The heat transfer member 24 is formed by bending one plate having a plurality of through holes 26 into a plurality of layers, and sandwiching an air layer between the layers. Since the structure of the heat transfer member 24 is simple, there is an advantage that the manufacturing cost can be reduced. The heat transfer member 24 receives heat from the heat energy imparting means 25 to generate heat, but the heat energy imparting means 25 uses a ceramic heater that can quickly rise (heat) and can be made thin, and the heat transfer member 24 is An aluminum plate with good thermal conductivity is used. Of course, the heat energy applying means 25 may be other than a ceramic heater, and the heat transfer member 24 may be a copper plate having a better thermal conductivity than an aluminum plate.
Has the advantage that it is easy to downsize. The blower means 27 uses a blower fan that produces a large amount of air because of its high blowing efficiency, and this blower fan is similar to the fan system used in a dryer or the like.

Now, the procedure of hot air generation by the hot air means 22 will be described with reference to FIGS. 1 to 2. The air flow generated by the air blowing means 27 is heated by the heat transmitted from the heat energy applying means 25. The heat transfer member 24 is sprayed and flows into the heat transfer member 24 from the through hole 26 in the uppermost layer. The airflow flowing in from the through hole 26 of the uppermost layer is the same as the through hole 2 of the same uppermost layer.
The heat is taken from the periphery of the through hole 26 when flowing out of FIG.
Spread like the arrow. The airflow thus diffused contacts the plate portion of the heat transfer member 24 other than the periphery of the through hole 26 to remove heat, and the gap between the layers of the heat transfer member 24 formed by bending one plate. While being heated by the direct heat (shown by the broken line arrow) from the heat energy applying means 25 irradiated from the portion of (1), it flows into the through hole 26 of the next layer.
Similarly, the air flow removes heat from the heat transfer member 24 in each layer to become hot air, and is blown out from the through hole 26 in the lowermost layer to melt the toner 2 on the surface of the print sheet 3 and fix it to the print sheet 3.

The structure of the heat transfer member 24 of the fixing device 21 may be other than the one formed by a single plate as shown in FIG. For example, as shown in FIG. 3, a plurality of aluminum members provided with a plurality of through holes 26 may be laminated to form a heat transfer member 24. If the through holes 26 are also provided on the side surface of the heat transfer member 24, thermal energy is increased. Since the air flow is also heated by the direct heat from the applying means 25 (shown by the broken line arrow), the heat transfer efficiency of the air flow is further improved. The flow of the air flow in this case is almost the same as that shown in FIG.

In the fixing device 21 of the present invention, the air flow flowing out from the through hole 26 does not go straight but diffuses to some extent and reaches the through hole 26 of the next layer. As a result of the wider contactable area than in the conventional example, the efficiency of heat exchange between the airflow and the heat transfer member 24 is significantly improved. In addition, in each layer of the heat transfer member 24, the air flow is heated even by the direct heat from the thermal energy applying means 25, so that the heat exchange efficiency is definitely improved as compared with the conventional example.

1 to 3 described above, the fixing device 21 is composed of the hot air means 22 and the supporting member 23. However, as shown in FIGS.
2, the support member 23 and the cold air means 28 may be used.

The structure of the cold air means 28 is as shown in FIGS. 4 to 5, both of which are provided on the upstream side of the hot air means 22. In FIG. 4, cold air (which means that the air is not heated, which means room temperature) is generated by the air blowing means 27 configured by a blower fan or the like, and is blown from the nozzle 29 toward the printing paper 3 side to form an air curtain. Hot air means 22
The hot air blown out from does not reach the upstream of the cold air means 28. When the toner 2 is transferred to the printing paper 3, there is a photoconductor on the upstream side of the hot air means 22, and when heated by the hot air, the photoconductor is deteriorated and the image quality is deteriorated. Further, the toner 2 visualized on the photoconductor may also be melted by hot air, and if the melted toner 2 adheres to the photoconductor, the photoconductor must be cleaned. Therefore, in order to prevent the hot air generated by the hot air means 22 from reaching the upstream side of the hot air means 22, the cold air means 28 is installed and the cold air means 28 is provided.
The cold air generated in step 1 forms an air curtain to block the hot air. In FIG. 5, the cold air means 28 is formed integrally with the hot air means 22, the air flow generated by the air blowing means 27 is branched to the cold air means 28 side and the hot air means 22 side, and the cool air is blown out from the nozzle 29. A curtain is formed to block the hot air blown from the hot air means 22. In addition,
In the case of the cold air means 28 shown in FIG. 5, since the air blowing means 27 is shared with the hot air means 22, it contributes to downsizing of the apparatus and reduction of manufacturing cost.

By the way, the fixing device of the present invention can be applied to an image forming apparatus other than the electrophotographic system (toner system), for example, a thermal transfer system image forming system using a thermal transfer film as a fusible recording material. It can also be applied to.

In the case of a thermal transfer type image forming apparatus, it is preferable to use a printing paper which is smooth due to the characteristics of the transfer type.
However, it is now common to use plain paper such as copy paper, and there is an urgent need to overcome print quality deterioration such as white spots when plain paper having low smoothness is used. The white spots referred to here mean that, in the case of a printing paper having a low smoothness, ink is placed on the convex portions, but no ink is placed on the concave portions, and white ink is lost around the concave portions.

Therefore, when the printing paper having such white spots is heated by the fixing device of the present invention, the ink on the convex portion is melted and soaks into the printing paper to spread, and the white spots around the concave portion. Will be filled up. for that reason,
After fixing, the ink transfer surface of the printing paper becomes glossy and beautiful, and the final printing quality is greatly improved.

[0038]

As described above, according to the present invention, a supporting member for supporting a recording medium having a fusible recording material attached thereto, and recording provided so as to face a surface of the supporting member for supporting the recording medium. A heat transfer member having a high heat conductivity, comprising a plurality of through holes provided with a plurality of through holes, and a heat transfer member having a high heat conductivity, and a heat transfer member having a high heat conductivity. It is composed of a heat energy applying means for giving energy and a blowing means for sending air to the through hole of the heat transfer member, and the heat transfer member is constituted by a plurality of layers of plates sandwiching an air layer therebetween. As a result, not only the through hole but also both sides of the plate provided with the through hole can be brought into contact with air, and the heat of the heat transfer member can be efficiently transferred to the air. The plate with through holes can be made thin to reduce the heat capacity of the heat transfer member. By the smaller, the shortening of warm-up time, advantageous effect that it is possible to realize low power consumption can be obtained.

Further, since the heat transfer member is formed of a plurality of layers by bending one plate, the plurality of layers can be formed by one plate, so that the structure of the heat transfer member can be simplified and the heat transfer member can be formed. The advantageous effect that the cost can be reduced is obtained.

Further, by using a ceramic heater as the heat energy applying means, the heat energy applying means can be made thin, the hot air means can be downsized, and the degree of freedom of arrangement of the fixing device in the electrophotographic apparatus or the like can be increased. The advantageous effect that it is possible is obtained.

Further, by using a blower fan as the air blowing means, it is possible to send a wind having a sufficient wind pressure to the heat transfer member, reliably send out the air from the through hole, and blow the hot air to the recording medium, thereby fixing the air. The advantageous effect of preventing the recording medium from floating inside the apparatus is obtained.

Further, when the recording material is toner, a blowing means for blowing a wind having a temperature lower than that of the hot air means to the recording medium is provided on the upstream side of the hot air means in the conveying direction of the recording medium. The blowing of hot air into the toner adhering process, etc. is blocked by the air from the air blowing means, so that the melting of the toner in the toner adhering process, etc. and the deterioration of the photoconductor, etc. due to heat can be prevented. It is possible to obtain an advantageous effect that it is possible to prevent the deterioration of the image quality due to the deterioration of the image quality.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a structure of a fixing device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a flow of an air flow that has flown into a heat transfer member of a fixing device according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a structure of a fixing device according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing a structure of a cool air unit of a fixing device according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing a structure of a cool air unit of a fixing device according to an embodiment of the present invention.

FIG. 6 is a schematic diagram showing the structure of a conventional contact-type fixing device.

FIG. 7 is a schematic view showing a printing surface fixed by a conventional contact type fixing device.

FIG. 8 is a schematic diagram showing a printing surface fixed by a conventional contact-type fixing device.

FIG. 9 is a schematic view showing a printing surface fixed by a conventional contact type fixing device.

FIG. 10 is a schematic view showing a printing surface fixed by a conventional contact type fixing device.

FIG. 11 is a schematic diagram showing a case where a conventional contact type fixing device is used in a fixing process of an orthogonal transfer type image forming apparatus.

FIG. 12 is a schematic diagram showing the structure of a conventional non-contact fixing device.

[Explanation of symbols]

1 fixing device 2 toner 3 printing paper 4 heating roller 5 pressure roller 6 dirt 7 Tail 8 fixing device 9 Hot air means 10 heating element 11 through holes 12 Blower means 21 Fixing device 22 Hot air means 23 Support member 24 Heat transfer member 25 means for applying thermal energy 26 through holes 27 Blower means 28 Cold Air Means 29 nozzles

Continuation of the front page (56) Reference JP-A-4-48573 (JP, A) JP-A-6-3985 (JP, A) JP-A-51-11451 (JP, A) JP-A-62-264083 (JP , A) Actual development Sho 48-75234 (JP, U) Actual development Sho 57-160167 (JP, U) Actual development Sho 61-70857 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G03G 13/20 G03G 15/20

Claims (6)

(57) [Claims] 1. A support member for supporting a recording medium having a fusible recording material adhered thereto, and hot air means for blowing hot air to the recording medium provided facing a surface of the supporting member for supporting the recording medium. A heat transfer member having a high thermal conductivity, the heat transfer means having a plurality of through-holes provided with a plurality of through holes and a layer of air sandwiched between the heat transfer means, and a heat energy applying means for applying heat energy to the heat transfer member. And a blower unit for sending wind to the through hole of the heat transfer member. 2. The fixing device according to claim 1, wherein the heat transfer member is formed by bending one plate into a plurality of layers. 3. The fixing device according to claim 1, wherein the heat energy applying means is a ceramic heater. 4. The fixing device according to claim 1, wherein the blower unit is a blower fan. 5. The fixing device according to claim 1, wherein the recording material is toner. 6. A cold air unit for blowing a wind having a temperature lower than that of the hot air unit to the recording medium upstream of the hot air unit in the conveying direction of the recording medium.
The fixing device according to any one of 3, 4, and 5.