JPH06308847A - Fixing device - Google Patents

Abstract

PURPOSE:To improve the strength and outside diameter precision of an end part for attaching the driving gear of a heating roller, thermal efficiency and the distribution of a temperature, in a fixing device. CONSTITUTION:In the fixing device 1 using one of a pair of fixing rollers as a hearing roller 2 and the other as a pressure roller 3 and heating/pressurizing/ fixing an image 9 on a transfer material 8 by the fixing rollers 2 and 3, rings 11 are force-fitted into both end parts of the heating roller 2, as a characteristic. Therefore, the rings 11 are force-fitted into both end parts of the heating roller 2, so that even if the heating roller is thin, the strength of both end parts is increased by the rings 11, to make the work and grinding of both end parts easy as well and easily obtain the outside diameter precision and simultaneously, heat is hardly released to make the thermal efficiency and the distribution of the temperature excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a facsimile and a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a toner image formed on an image carrier through a charging, exposing and developing process is transferred onto a transfer material such as recording paper and then fixed on the transfer material by a fixing device. This fixing device is provided with a pair of fixing rollers, that is, a heating roller having a heating source such as a halogen lamp, and a pressure roller rotatably pressed against the heating roller. In this state, the temperature control circuit controls the energization of the heating source to control the surface temperature of the heating roller to a constant value, and the transfer material is passed between the heating roller and the pressure roller to heat and apply heat. By applying pressure, the unfixed toner on the transfer material is melted by heat and fixed. In such a fixing device, the heating roller is connected to a drive source such as a motor via a drive gear attached to one end of the heating roller to rotate, but conventionally, the drive gear is not attached. As shown in FIG. 8A, the heating roller 2
The U-cut portion 23 is provided at the end of the drive gear 22
The drive gear 22 is inserted by aligning the protrusion 24 provided on the side, and a retaining ring is fitted and fixed in the groove 27, or the D-cut portion 2 is attached to the end of the heating roller 21 as shown in FIG.
5 was provided, the D cut portion of the drive gear 22 was fitted therein, and a retaining ring was fitted in the groove portion 27 to be fixed (Japanese Utility Model Publication No. 63-2967, etc.).

[0003]

However, in the method of the prior art, when the heating roller is manufactured with a wall thickness of 1 mm or less, the strength is weak because the wall thickness is thin, and it is difficult to adjust the outer diameter by polishing or the like. Since the outer diameter tolerance of the gear mounting portion and the bearing portion at the end of the heating roller does not come out, there is a problem that the gear and the bearing do not come in.When this is mass-produced, a large yield occurs due to the above problems. There was a problem that the cost was high. Further, when the heating roller is thin, the temperature at both ends of the heating roller during standby becomes low as shown in FIG. 9, and in order to improve this, if the amount of light emission at both ends of the halogen lamp is increased, both ends during standby Although the temperature rises and the temperature distribution becomes better, when a small-sized transfer paper is continuously fed, the temperatures at both ends become higher as shown in FIG. 10, and the release layer (fluorine-based resin layer such as PFA) of this part is increased. However, if the paper becomes useless or if a large-sized transfer paper is immediately passed through, the temperature of this part is high, which causes a problem of hot offset.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fixing device having means for solving the above problems even when the thickness of the heating roller is 1 mm or less. .

[0005]

In order to achieve the above object, the invention of claim 1 uses one of a pair of fixing rollers as a heating roller and the other as a pressure roller, and the fixing roller forms an image on a transfer material. In a fixing device for fixing by heating / pressurizing, rings are press-fitted into both ends of the heating roller.

According to a second aspect of the present invention, in the fixing device, the reflectance inside the ring is different from the reflectance inside the center of the heating roller.

According to a third aspect of the invention, one of the pair of fixing rollers is a heating roller and the other is a pressure roller, and the fixing roller heats and presses the image on the transfer material to fix the image. In a fixing device in which the heating roller is composed of a straight pipe and uses a halogen lamp whose light emission amount is larger at the end than at the center as a heat source, the thickness of both ends of the heating roller is made thicker than the paper passing range. It is characterized by being present.

According to a fourth aspect of the present invention, in the fixing device, one of the pair of fixing rollers is a heating roller and the other is a pressure roller, and the fixing roller heats and presses the image on the transfer material to fix the image. The roller is characterized by being bent over the entire circumference of both ends.

According to a fifth aspect of the present invention, in the fixing device, the reflectance of the inner surface of the transitional bent portion and the reflectance of the inner portion of the center of the heating roller are different from each other.

According to a sixth aspect of the invention, in the fixing device according to the first to fifth aspects, an elongated hole is provided on the driving portion side of the heating roller.

According to a seventh aspect of the present invention, in the fixing device according to the first to fifth aspects, an elongated hole is provided on the driving portion side of the heating roller, and the drive gear is stopped via a detent key corresponding to the elongated hole. It is characterized by having done.

[0012]

In the fixing device of the present invention, since the rings are press-fitted into both ends of the heating roller, the strength of both ends is increased by the rings even if the heating roller is thin, and both ends can be easily processed. Therefore, the accuracy of the outer diameter can be easily obtained.

Further, in the fixing device according to the second aspect of the invention, since the reflectance inside the ring and the reflectance inside the center of the heating roller are made different, the thermal efficiency and temperature distribution of the heating roller are improved. Can be achieved.

In the fixing device according to the third aspect of the present invention, since the thickness of both ends of the heating roller is made thicker than that of the paper-passing area, the strength of both ends is increased and both ends are easily processed.
It is also easy to obtain the outer diameter accuracy. Further, the temperature distribution of the heating roller can be improved.

In the fixing device of the fourth aspect, since the heating roller is bent over the entire circumference of both ends,
The same effect as can be obtained.

Further, in the fixing device according to the fifth aspect, since the reflectance of the inner surface of the crossover bent portion and the reflectance of the inner portion of the heating roller center are made different, the thermal efficiency and the temperature distribution of the heating roller. Can be improved.

In the fixing device of the sixth aspect, since the elongated hole is provided on the driving portion side of the heating roller, the driving gear can be fixed by utilizing the elongated hole.

According to another aspect of the fixing device of the present invention, an elongated hole is provided on the drive portion side of the heating roller, and the drive gear is stopped via the rotation preventing key corresponding to the elongated hole. Assembling is improved.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1A is a diagram schematically showing a configuration example of a fixing device to which the present invention is applied.
Includes a pair of fixing rollers including a heating roller 2 and a pressure roller 3. The heating roller 2 has a built-in heating source 10 such as a halogen lamp. Further, the surface temperature of the heating roller 2 is detected by a temperature detecting means 5 such as a thermistor, and the detection signal is fed back to a temperature control circuit (not shown) to control the light emission amount or the heat generation amount of the heating source 10 and the heating roller 2 The surface temperature is controlled to be constant. In the above fixing device, the heating roller 2 is kept in a state where the surface temperature of the heating roller 2 is controlled to be constant.
The transfer material 8 on which the unfixed toner image 9 has been transferred is passed between the pressure roller 3 and the pressure roller 3 and heated and pressed to heat-melt the unfixed toner on the transfer material and fix it on the transfer material. Let
Then, the transfer material 8 after fixing is peeled off from the heating roller 2 by the separation claw 4 and discharged by the discharge rollers 6 and 7.

In the fixing device as described above, if the thickness of the heating roller 2 is 1 mm or more, the structure of the drive gear mounting portion at the end of the heating roller is as shown in FIGS. 8 (a) and 8 (b). It is effective to do so, but when the wall thickness is 1 mm or less,
The problem as described above occurs. Therefore, in the present invention, as shown in FIGS. 1B and 1C, rings 11 made of stainless steel (SUS), aluminum (Al), or the like are press-fitted into both ends of the heating roller 2 (claims). 1). In this way, the rings 11 are press-fitted into both ends of the heating roller 2 to increase the strength of the ends, so that they will not be broken even during the next step of processing the ends or polishing for adjusting the outer diameter, and the outer edges will not be broken. Diameter accuracy has also come out. Further, by press-fitting the ring 11, it is difficult for heat to escape from the end portion of the heating roller 2, and the effect that the end portion temperature rises and the thermal efficiency improves is also obtained.

By the way, as a measure for improving the heat efficiency and temperature distribution of the heating roller 2, in the present invention, the reflectance inside the ring 11 and the reflectance inside the center of the heating roller are made different (claim 2). ). For example, polishing such as electrolytic polishing and chemical polishing, surface treatment (evaporation, alumite treatment, plating, etc.) is performed on the ring 11 so that the reflectance inside the ring 11 (on the heating roller side) is 70% or more. Has been applied. Here, FIG. 2 is a view showing the temperature distribution in the longitudinal direction (axial direction) of the heating roller 2, and the solid line a is the ring 1.
1 shows the temperature distribution in the standby state when the polishing or the surface treatment is not performed, and the broken line b indicates the standby temperature distribution when the ring 11 is subjected to the polishing or the surface treatment. In other words, a halogen lamp is normally provided inside the heating roller as a heating source, and the inner surface of the roller is blackened. However, the ring 11 press-fitted at the end of the roller is subjected to the above-mentioned treatment to improve the reflectance of the inner surface of the ring. By raising the temperature to 70% or more, the light leaking to the end is reflected by the ring 11 and returns to the inside, and the temperature distribution can be improved as shown in FIG.

Next, FIG. 3 is a cross-sectional view of an essential part of a heating roller according to another embodiment of the present invention, in which the thickness of both ends of the heating roller 2 is made thicker than the paper-passing area ( Claim 3). As shown in FIG. 3, by making the thickness of both ends of the heating roller 2 thicker than the paper passing range, the strength of the ends can be increased as in the case of press-fitting the ring shown in FIG. Even in the next step, when processing both ends and adjusting the outer diameter, the outer diameter will not be broken and the outer diameter accuracy will be improved. Also,
As shown in the graph of FIG. 4, when the amount of light emission at both ends of the halogen lamp is increased so that the temperature distribution during standby becomes substantially uniform as indicated by the solid line a, a conventional heating roller with a uniform thickness is used. In this case, at the time of continuous feeding of small size paper, the temperature at both ends becomes high and the temperature distribution becomes as indicated by the broken line of c. However, as in the present embodiment, the wall thickness at both ends of the heating roller 2 is passed. When the size is thicker than the range part, even when continuously passing small size paper, the temperature rise is reduced due to the increase in the heat capacity of the edge part, and the temperature distribution becomes as shown by the one-dot chain line in b. The problem that the temperature of both ends becomes too high during continuous paper feeding is improved.

Next, FIG. 5 is a sectional view of the main part of a heating roller showing still another embodiment of the present invention. The present embodiment is characterized in that it is located at both ends of the heating roller 2 and is bent over the entire circumference of both ends of the heating roller 2 (claim 4).
By inserting this bent portion, it is possible to increase the strength of both ends of the heating roller 2 as in the case where the ring shown in FIG. 1 is inserted, and it may be broken during polishing in the next step of adjusting the outer diameter. The outer diameter accuracy is improved and the thermal efficiency is improved. Further, as compared with the case of inserting the ring, only the bending of the end portion is required, so that the number of parts can be reduced and the cost can be reduced. In addition, as the material of the pipe that constitutes the heating roller 2, iron (Fe), stainless steel (SUS), copper (Cu), brass, aluminum (Al)
Are used.

Further, as a measure for improving the thermal efficiency and the temperature distribution of the heating roller 2, in the present invention, the reflectance of the inner surface of the crossover bent portion and the reflectance of the inner portion of the heating roller center are made different (claims). Item 5). For example, polishing such as electrolytic polishing and chemical polishing and surface treatment (evaporation, alumite treatment, plating, etc.) are performed so that the reflectance of the inner surface of the cross-bent portion of the heating roller 2 becomes 70% or more. In this way, by increasing the reflectance of the inner surface of the crossover bent portion of the heating roller 2 to 70% or more, the light leaking to the end is reflected by the inner surface of the bent portion and returns to the inside, so that the thermal efficiency and the temperature distribution can be improved. .

Next, FIG. 6 is a perspective view of a driving side end portion and a driving gear of a heating roller showing still another embodiment of the present invention. The feature of this embodiment is that the elongated hole 14 is provided on the driving portion side of the heating roller 2 (claim 6). That is, since the drive gear 12 cannot be stopped when the end portion of the heating roller 2 remains in the state shown in FIGS. 1, 3 and 5, as shown in FIG. A long hole 14 is also formed in the portion, and a hole is also formed in the drive gear 12 side, and the drive gear 12 is fitted to the end portion of the heating roller 2, and the long hole 14 and the gear side hole are aligned with each other. Insert the key 13 from above and fix it. Further, if the retaining ring groove 15 is provided in the heating roller 2 and the retaining ring is fitted into the groove 15 after fixing the drive gear 12, the drive gear 12 can be reliably fixed. Note that FIG. 6 shows an example in which the end portion of the heating roller 2 is provided with the same crossover bending portion as in FIG. 5, but instead of this, FIG.
The ring may be press-fitted as described above, or the roller end may be thickened as shown in FIG.

Next, FIG. 7 is a perspective view of a driving-side end portion and a driving gear of the heating roller according to still another embodiment of the present invention. The feature of the present embodiment is that the driving roller side of the heating roller 2 is provided with an elongated hole 14, and the rotation preventing key 16 is provided corresponding to the elongated hole 14.
Drive gear 12 through the detent key 16
Is to stop the operation (Claim 7). That is, the elongated hole 14 is opened in the gear fixing portion on the drive portion side of the heating roller 2, the rotation preventing key 16 is inserted corresponding to the long hole 14, and the shape of the rotation preventing key 16 is provided on the drive gear 12 side. The drive gear 12 is fitted to the end portion of the heating roller 2 and slid to bring it to the detent key portion 16, and the detent key 16 is engaged with the gear side recess portion. After that, if the retaining ring is fitted into the retaining ring groove 15, the drive gear 12 can be easily fixed to the heating roller 2. As described above, in the configuration in which the rotation preventing key 16 is attached to the heating roller 2 in advance and the drive gear 12 is fixed,
Since the efficiency at the time of assembling is higher than the case where the drive gear 12 is fitted into the heating roller 2 and the holes are aligned and then the key 13 is inserted, the productivity is improved. In addition, FIG.
This is an example in which the crossover portion similar to that of FIG. 5 is provided at the end portion of the heating roller 2, but instead of this, a ring may be press-fitted as shown in FIG. 1 or the roller end portion as shown in FIG. The wall thickness of the part may be increased.

[0027]

As described above, in the fixing device according to the first aspect of the present invention, the rings are press-fitted into both ends of the heating roller. Therefore, even if the heating roller has a small thickness, the strength of both ends can be increased by the rings. It becomes easier to process and polish both ends,
Outer diameter accuracy is easier to obtain, and heat is less likely to escape from the ends, so thermal efficiency is also improved.

Further, in the fixing device according to the second aspect of the present invention, the reflectance of the inside of the ring is set to, for example, 70% or more, and the reflectance of the inside of the center of the heating roller is made different, so that the thermal efficiency of the heating roller is increased. Also, the temperature distribution can be improved.

In the fixing device according to the third aspect of the present invention, since the thickness of both ends of the heating roller is thicker than that of the paper-passing range, the strength of both ends is increased, and both ends are easily processed and polished. It is also easy to obtain the outer diameter accuracy. In addition, since the thickness of both ends is large, the temperature distribution can be improved when continuously passing small size paper.

In the fixing device of claim 4, since the heating roller is bent over the entire circumference of both ends thereof,
The same effect and advantage can be obtained, and the cost can be reduced because the number of parts is reduced as compared with the first aspect.

Further, in the fixing device of the fifth aspect, the reflectance of the inner surface of the crossover bent portion is, for example, 70% or more,
By providing a difference in the reflectance at the center inner side of the heating roller, the thermal efficiency and temperature distribution of the heating roller can be improved in addition to the effect of the fourth aspect.

According to the fixing device of claim 6,
In addition to the configurations of 5 to 5, by providing the driving roller side of the heating roller with the elongated hole, the driving gear can be easily fixed by utilizing the elongated hole.

In the fixing device of claim 7, claim 1
In addition to the constitutions of 5 to 5, the driving gear is easily fixed by providing the heating roller with an elongated hole on the driving portion side and stopping the driving gear via the rotation preventing key corresponding to the elongated hole. In addition, the assembling property of the drive gear is improved, and the productivity is improved.

[Brief description of drawings]

1A and 1B are diagrams showing an embodiment of the present invention, in which FIG. 1A is a diagram schematically showing a configuration example of a fixing device to which the present invention is applied, and FIG. 1B is an end portion of a heating roller; FIG. 3C is a perspective view of a main part of the ring, and FIG. 7C is a perspective view of the main part of the heating roller showing a state in which the ring is press-fitted into the end portion.

FIG. 2 is a temperature distribution a of the heating roller shown in FIG. 1 in a standby state when the inner surface of the ring is not subjected to the reflectance improving process, and a heating roller b when the inner surface of the ring has a reflectance of 70% or more. It is a figure which shows the temperature distribution of.

FIG. 3 is a cross-sectional view of essential parts of a heating roller according to another embodiment of the present invention.

FIG. 4 is a diagram showing a temperature distribution a during standby of the heating roller shown in FIG. 3, a temperature distribution b during continuous feeding of small size paper, and a temperature distribution c during continuous feeding of small size paper of the conventional heating roller. Is.

FIG. 5 is a cross-sectional view of a main part of a heating roller according to still another embodiment of the present invention.

FIG. 6 is a perspective view of a drive-side end portion and a drive gear of a heating roller according to still another embodiment of the present invention.

FIG. 7 is a perspective view of a drive-side end portion and a drive gear of a heating roller according to still another embodiment of the present invention.

FIG. 8 is an explanatory diagram of a conventional technique.

FIG. 9 is a diagram showing a temperature distribution of a conventional heating roller during standby.

FIG. 10 is a diagram showing a temperature distribution of a conventional heating roller during standby and during continuous passage of small-sized paper.

[Explanation of symbols]

 1: Fixing device 2: Heating roller 3: Pressing roller 8: Transfer material 9: Toner image 10: Heating source (halogen lamp etc.) 11: Ring 12: Drive gear 13: Key 14: Slotted hole 16: Anti-rotation key

Claims (7)

[Claims] 1. A fixing device in which one of a pair of fixing rollers is a heating roller and the other is a pressure roller, and the fixing roller heats and presses an image on a transfer material to fix the image on both ends of the heating roller. A fixing device in which a ring is press-fitted. 2. The fixing device according to claim 1, wherein the reflectance inside the ring is different from the reflectance inside the center of the heating roller. 3. An apparatus for fixing and fixing an image on a transfer material by heating and pressurizing an image on a transfer material by the fixing roller, wherein one of the pair of fixing rollers is a heating roller and the other is a pressure roller. In a fixing device using a halogen lamp having a larger amount of light emission than the center as a heat source, the thickness of both ends of the heating roller is made thicker than the paper-passing range. And fixing device. 4. A fixing device in which one of a pair of fixing rollers is a heating roller and the other is a pressure roller, and the fixing roller heats and presses an image on a transfer material to fix the image on the transfer material. A fixing device characterized by being bent over the circumference. 5. The fixing device according to claim 4, wherein a reflectance of an inner surface of the crossover bent portion and a reflectance of a central inner portion of the heating roller are different from each other. 6. The fixing device according to claim 1, wherein an elongated hole is provided on the driving portion side of the heating roller. 7. The fixing device according to any one of claims 1 to 5, wherein an elongated hole is provided on the driving portion side of the heating roller, and the drive gear is stopped via a rotation preventing key corresponding to the elongated hole. Characterizing fixing device.