JP3318039B2 - 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 fixing device used in an image forming apparatus such as a copying machine, a facsimile, a printer and the like.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a toner image formed on an image bearing member is transferred to a transfer material such as recording paper through a charging, exposure, and development process, and is then transferred to a transfer material by a fixing device. The fixing device includes a pair of fixing rollers, that is, a heating roller having a built-in heating source such as a halogen lamp, and a pressure roller rotatably pressed against the heating roller. With the temperature control circuit controlling the energization of the heating source and keeping the surface temperature of the heating roller constant, the transfer material is passed between the heating roller and the pressure roller to heat and heat. By pressing, 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 driving source such as a motor via a driving gear attached to one end of the heating roller so as to be rotated. Next, as shown in FIG.
1 is provided with a U-cut portion 23 at which the drive gear 22 is mounted.
The drive gear 22 is inserted by aligning the protrusions 24 provided on the side, and a retaining ring is fitted and fixed in the groove 27. Alternatively, as shown in FIG.
5, a D-cut portion of the drive gear 22 is fitted therein, and a retaining ring is fitted and fixed in the groove portion 27 (Japanese Utility Model Laid-Open No. 63-2967).

[0003]

However, in the prior art method, when the heating roller is manufactured with the thickness of the heating roller being 1 mm or less, the strength is weak due to the thin thickness, 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 arises a problem that a gear or a bearing does not enter, and when mass-producing the same, a large yield comes out of the above problem, There was a problem that the cost was high. When the thickness of the heating roller is reduced, the temperature at both ends of the heating roller during standby becomes low as shown in FIG. 9, and in order to improve this, the light emission amount at both ends of the halogen lamp is increased. Although the temperature rises and the temperature distribution is improved, when small-size transfer paper is continuously passed, the temperature at both ends is increased this time as shown in FIG. 10, and the release layer (a fluorine-based resin layer such as PFA) of this part is obtained. However, when a large-size transfer paper is passed immediately, there is also a problem that a hot offset is generated because the temperature of this portion is high.

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

[0005]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
As a means for fixing , in a fixing device in which one of a pair of fixing rollers is a heating roller and the other is a pressing roller, and the fixing roller heats and presses an image on a transfer material and fixes the image, the heating roller has a thick wall. When a thin pipe is used, a ring for reinforcing the strength of the both ends and preventing heat from escaping from both ends is pressed into both ends of the heating roller.
There is a configuration called .

Further, in the above Symbol fixing device includes an inner reflectance of the ring to prevent escape of heat from and opposite end portions with strength reinforcing press-fitted at both ends of the heating roller,
Heating roller to have a difference in a central inner portion reflectance of the reflectance of the inside of the ring is set to be 70% or more.

An apparatus for fixing an image on a transfer material by heating and pressing the fixing roller by using one of a pair of fixing rollers as a heating roller and the other as a pressing roller, wherein the heating roller is a straight pipe In a fixing device using a halogen lamp having a light emission amount larger at the end than at the center as a heating source, there is also a means for increasing the thickness of the both ends of the heating roller as compared with the paper range. .

As another means for achieving the above object, one of a pair of fixing rollers is a heating roller and the other is a pressing roller, and the image on the transfer material is fixed by heating and pressing with the fixing roller. In the fixing device, when the heating roller is formed of a thin-walled pipe, it is used to reinforce strength of both ends of the heating roller and to prevent heat from escaping from both ends. There is a configuration in which a bent portion formed by bending both ends inward at substantially right angles is provided over the entire circumference. According to the first aspect of the present invention, in order to reinforce strength of both ends of the heating roller and to prevent heat from escaping from both ends, the both ends of the heating roller are provided along the entire circumference of the both ends. A configuration is adopted in which a bent portion is formed by bending the portion at a substantially right angle inward.

According to a second aspect of the present invention, in the fixing device, an inner surface of a bent portion for reinforcing strength and preventing heat from escaping from both ends is provided around the both ends of the heating roller. A difference is made between the reflectance and the reflectance at the center inside the heating roller so that the reflectance of the inner surface of the bent portion is 70% or more.

According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the heating roller is provided with bent portions for reinforcing strength at both ends and for preventing heat from escaping from both ends. An elongated hole is provided in the gear fixing portion at the end of the drive unit, and a hole is also provided in the drive gear, and the drive gear is fitted to the end of the heating roller, and the position of the elongated hole and the hole on the gear side is adjusted. Then, a key is inserted into both holes to fix the drive gear.

According to a fourth aspect of the present invention, in the fixing device according to the first or second aspect, the heating roller is provided with a bent portion for reinforcing the strength at both ends and for preventing heat from escaping from both ends. An elongate hole is provided in the gear fixing portion at the end of the driving portion, a detent key is inserted into the elongate hole, and the driving gear is stopped via the detent key.

[0012]

Among the above-mentioned means, in a fixing device of a reference example, a ring is press-fitted at both ends of a heating roller .
However, even if the thickness of the heating roller is thin, the strength of both ends is increased by the ring, the processing of both ends is easy, and the accuracy of the outer diameter is easily obtained.

In the above fixing device, the reflectance inside the ring and the reflectance inside the center of the heating roller are made different so that the reflectance inside the ring becomes 70% or more. As a result, the thermal efficiency and temperature distribution of the heating roller can be improved.

Incidentally, in a fixing device using a halogen lamp in which the heating roller is constituted by a straight pipe and the amount of light emission of which is larger at the end than at the center as a heating source, the thickness of the both ends of the heating roller is limited in the paper passing range. There is also a means of increasing the thickness compared to the portion, and in this case also, the strength at both ends is increased, the processing at both ends is facilitated, and the accuracy of the outer diameter is easily obtained. Further, the temperature distribution of the heating roller can be improved.

[0015] Of the above means, the invention according to claim 1 is characterized in that:
In order to reinforce the strength of both ends of the heating roller and to prevent heat from escaping from both ends, the both ends of the heating roller were bent at substantially right angles inward over the entire periphery of both ends. In a fixing device having a bent portion, the same operation as that in which a ring is pressed into both ends of a heating roller can be obtained.

Further, in the fixing device according to the present invention, the reflectance of the inner surface of the bent portion and the reflectance of the inner portion of the center of the heating roller are made different from each other so that the reflectance of the inner surface of the bent portion is 7%.
By setting it to 0% or more, the thermal efficiency and temperature distribution of the heating roller can be improved.

In the fixing device according to the third aspect, the gear fixing portion at the drive unit side end of the heating roller provided with bent portions for reinforcing the strength at both ends and for preventing heat from escaping from both ends. In addition to providing a slot on the drive gear side, a hole is also provided on the drive gear side, and the drive gear is fitted to the end of the heating roller to align the position of the slot with the hole on the gear side. Since the drive gear is fixed by inserting a key, the drive gear can be fixed to the thin heating roller using the long hole.

According to a fourth aspect of the present invention, in the fixing device according to the fourth aspect, a gear fixing portion at a driving unit side end of the heating roller provided with a bent portion for reinforcing strength at both ends and for preventing heat from escaping from both ends. Is provided with a long hole, a detent key is inserted corresponding to the long hole, and the drive gear is stopped via the detent key, so that the assemblability of the drive gear is improved.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a view schematically showing a configuration example of a fixing device to which the present invention is applied.
Has a pair of fixing rollers including a heating roller 2 and a pressure roller 3, and 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. The surface temperature is controlled to be constant. In the above-described fixing device, the heating roller 2 is controlled in a state where the surface temperature of the heating roller 2 is controlled to be constant.
The unfixed toner image 9 is transferred between the transfer material 8 and the pressure roller 3, and the paper is heated and pressurized, so that the unfixed toner on the transfer material is melted by heat and fixed on the transfer material. Let it.
Then, the transfer material 8 after fixing is peeled off from the heating roller 2 by the separation claw 4 and is discharged by the discharge rollers 6 and 7.

In the fixing device as described above, if the thickness of the heating roller 2 is usually 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). Is effective, but if the wall thickness is 1 mm or less,
The above-described problem occurs. Therefore, one configuration example
As shown in FIGS. 1B and 1C, stainless steel (SUS) or aluminum (A)
It presses the ring 11 formed in l) and the like. in this way,
The ring 11 is press-fitted into both ends of the heating roller 2 to increase the strength of the end, so that it does not break during the processing of the end or the polishing of the outer diameter, which is the next step, and the outer diameter accuracy is improved. It became so. In addition, the press-fitting of the ring 11 makes it difficult for heat to escape from the end of the heating roller 2, thereby increasing the temperature of the end and improving the thermal efficiency.

[0021] Incidentally, the improvement of thermal efficiency and temperature distribution in the heating roller 2, to have a front Symbol inner reflectance of the ring 11, a difference in the reflectivity of the heating roller central inner portion
You. For example, the ring 11 is polished such as electrolytic polishing and chemical polishing, and surface treatment (evaporation, alumite treatment, plating, etc.) such that the reflectance inside the ring 11 (on the heating roller side) is 70% or more. Is given. Here, FIG.
Is a diagram showing a temperature distribution in the longitudinal direction (axial direction) of the heating roller 2, wherein a solid line a represents a temperature distribution during standby when the above-mentioned polishing or surface treatment is not performed on the ring 11, and a broken line b represents a ring 11. 7 shows a temperature distribution during standby when the above polishing and surface treatment are performed. That is, a halogen lamp is usually contained inside the heating roller as a heating source,
Although the inner surface of the roller is blackened, the light leaking to the end is reflected by the ring 11 by performing the above-described processing on the ring 11 pressed into the end of the roller to increase the reflectance of the inner surface of the ring to 70% or more. Returning to the inside, the temperature distribution can be improved as shown in FIG.

Next, FIG. 3 is a sectional view of a main part showing another example of the configuration of the heating roller, in which the thickness of both ends of the heating roller 2 is made thicker than the paper passing area. As shown in FIG. 3, by making the thickness of both ends of the heating roller 2 thicker than the paper-passing area, the strength of the end can be increased in the same manner as when the ring shown in FIG. 1 is press-fitted. No breakage occurs at the time of processing the outer ends and the outer diameter is adjusted in the next step, and the outer diameter accuracy is improved. Further, as shown in the graph of FIG. 4, when the light emission amount at both ends of the halogen lamp is increased so that the temperature distribution at the time of standby becomes substantially uniform as shown by the solid line a, the conventional heating with a uniform thickness is performed. In the case of a roller, when the small-size paper is continuously passed, the temperature at both ends becomes high and the temperature distribution becomes as indicated by a broken line of c, but as in the present embodiment, the thickness of both ends of the heating roller 2 is reduced. In the case where the sheet is thicker than the sheet passing area, even when the small size sheet is continuously passed, the temperature rise is reduced by the amount of the heat capacity at the end, and the temperature distribution becomes as indicated by the dashed line b in FIG. The problem that the temperature at both ends becomes excessively high during continuous feeding of small-size paper is improved.

FIG. 5 is a sectional view of a main part of a heating roller according to an embodiment of the present invention. This embodiment is characterized in that the heating roller 2 is located at both ends, and as shown in FIG.
The present invention is characterized in that a bent portion which is formed by bending both ends inward at substantially right angles is provided over the entire circumference of both ends of the (claim 1). By inserting the bent portion, the strength of both ends of the heating roller 2 can be increased as in the case where the ring shown in FIG. 1 is inserted, and it is broken during the polishing of the outer diameter adjustment in the next step. The outer diameter accuracy is improved, and the thermal efficiency is improved. Further, as compared with the case where a ring is inserted, only the bending of the end portion is required, so that the number of parts is reduced and the cost can be reduced. The material of the pipe constituting the heating roller 2 is iron (Fe), stainless steel (SUS), copper (Cu), brass, aluminum (A).
l) and the like are used.

Further, as a measure for improving the thermal efficiency and the temperature distribution of the heating roller 2, in the present invention, a difference is provided between the reflectance of the inner surface of the bent portion and the reflectance of the central inner portion of the heating roller. 2). For example, polishing such as electrolytic polishing or chemical polishing, surface treatment (evaporation, alumite treatment, plating, etc.) is performed so that the reflectance of the inner surface of the bent portion of the heating roller 2 becomes 70% or more. As described above, by increasing the reflectance of the inner surface of the bent portion of the heating roller 2 to 70% or more, light leaking to the end portion 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 another embodiment of the present invention. The feature of the present embodiment is that an elongated hole 14 is provided on the drive unit side of the heating roller 2 (claim 3). That is, since the drive gear 12 is not stopped when the end of the heating roller 2 is in the state shown in FIGS. 1, 3, and 5, the gear is fixed on the drive unit side of the heating roller 2 as shown in FIG. Open a slot 14 in the part,
In addition, a hole is also formed in the drive gear 12 side so that the drive gear 12
Is fitted to the end of the heating roller 2 so that the position of the long hole 14 and the hole on the gear side are aligned, and the key 13 is inserted into the hole from above and fixed. Furthermore, if the retaining ring groove 15 is provided on the heating roller 2 and the retaining ring is fitted into the groove 15 after the driving gear 12 is fixed, the driving gear 12 can be securely fixed. still,
FIG. 6 shows an example in which a bent portion similar to that shown in FIG. 5 is provided at the end of the heating roller 2. Alternatively, a ring may be press-fitted as shown in FIG. 1, or as shown in FIG. Alternatively, the thickness of the roller end may be increased.

FIG. 7 is a perspective view of a drive gear end and a drive gear of a heating roller according to still another embodiment of the present invention. The feature of this embodiment is that a long hole 14 is provided on the drive unit side of the heating roller 2, and a detent key 16 is provided corresponding to the long hole 14.
Into the drive gear 12 through the detent key 16.
(Claim 4). That is, a long hole 14 is opened in the gear fixing portion on the drive unit side of the heating roller 2, a detent key 16 is inserted corresponding to the long hole 14, and the shape of the detent key 16 is formed on the drive gear 12 side. The drive gear 12 is fitted to the end of the heating roller 2 and slid and brought to the key portion 16 for rotation prevention. Then, 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 detent key 16 is attached to the heating roller 2 in advance and the drive gear 12 is fixed, FIG.
As described above, the efficiency at the time of assembling is higher than when the key 13 is inserted after the drive gear 12 is fitted to the heating roller 2 and the holes are aligned, thereby improving the productivity. In addition, FIG.
This is an example in which a bent portion similar to that shown in FIG. 5 is provided at the end of the heating roller 2. Alternatively, a ring may be press-fitted as shown in FIG. May be made thicker.

[0027]

As described in the foregoing, in the fixing apparatus having a structure that is press-fitted ring to both ends of the pressurized heat roller, increasing the strength of both ends by the ring be thinner wall thickness of the heating roller, both ends Processing and polishing are also facilitated, the outer diameter accuracy is easily obtained, and heat is hard to escape from the end, so that the thermal efficiency is improved.

Further, prior Symbol a ring inside the reflectivity, for example, more than 70%, by Ru to have a difference in the reflectivity of the heating roller central inner portion, thereby the improvement of the thermal efficiency and temperature distribution in the heating roller.

Incidentally, in a fixing device using a halogen lamp in which the heating roller is constituted by a straight pipe and the amount of light emission of which is larger at the end than at the center as a heating source, the thickness at both ends of the heating roller is limited to the paper passing range. There is also a means of increasing the thickness compared to the portion, and in this case also, the strength at both ends is increased, the processing and polishing of both ends are facilitated, and the accuracy of the outer diameter is easily obtained. Further, since the thickness at both ends is large, it is possible to improve the temperature distribution when small-size paper is continuously fed.

Here, in the fixing device of the first aspect,
In order to reinforce the strength of both ends of the heating roller and to prevent heat from escaping from both ends, the heating roller was bent substantially inward at right angles inward over the entire periphery of both ends. Since the bent portion is provided, the same operation and effect as the configuration in which the ring is press-fitted at both ends of the above-described heating roller can be obtained,
Further, as compared with the configuration in which the rings are press-fitted at both ends of the heating roller, the number of parts is reduced, so that the cost can be reduced.

In the fixing device according to the second aspect, the reflectance of the inner surface of the bent portion is set to, for example, 70% or more, and the reflectance at the center inside the heating roller is made different. In addition to the functions and effects described above, the thermal efficiency and temperature distribution of the heating roller can be improved.

[0032] In the fixing device according to the third aspect, the first aspect of the invention is the first aspect.
Or in addition to the constitution described in 2, the elongated hole is formed in the gear fixing portion at the drive unit side end of the heating roller provided with a bent portion for reinforcing the strength at both ends and preventing heat from escaping from both ends. A hole is also provided on the drive gear side, and the drive gear is fitted to the end of the heating roller to align the slot with the hole on the gear side, and then a key is inserted into both holes. As a result, the drive gear can be easily fixed to the thin heating roller using the long hole.

[0033] In the fixing device according to the fourth aspect, the first aspect is as follows.
Or in addition to the constitution described in 2, the elongated hole is formed in the gear fixing portion at the drive unit side end of the heating roller provided with a bent portion for reinforcing the strength at both ends and preventing heat from escaping from both ends. The driving gear can be easily fixed by inserting a rotation-stop key corresponding to the oblong hole and stopping the drive gear via the rotation-stop key, and The assemblability is improved, and the productivity is improved.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating an embodiment of the present invention, in which FIG. 1A schematically illustrates an example of the configuration of a fixing device to which the present invention is applied, and FIG. FIG. 3C is a perspective view of a main part of the heating roller, showing a state where the ring is pressed into an end portion.

FIG. 2 shows a temperature distribution a at the time of standby of the heating roller when the reflectivity improvement processing is not performed on the inner surface of the ring of the heating roller shown in FIG. 1, and a heating roller b when the reflectance of the inner surface of the ring is 70% or more. FIG. 4 is a diagram showing a temperature distribution of the present invention.

FIG. 3 is a sectional view of a main part of a heating roller showing 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-sized paper, and a temperature distribution c during continuous feeding of small-sized paper of the conventional heating roller. It is.

FIG. 5 is a sectional view of a main part of a heating roller showing still another embodiment of the present invention.

FIG. 6 is a perspective view of a drive-side end 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 driving-side end portion and a driving 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 at the time of standby.

FIG. 10 is a diagram showing a temperature distribution when a conventional heating roller is on standby and when a small-size sheet is continuously fed.

[Explanation of symbols]

 1: fixing device 2: heating roller 3: pressure roller 8: transfer material 9: toner image 10: heating source (halogen lamp, etc.) 11: ring 12: drive gear 13: key 14: long hole 16: key for rotation prevention

Continuation of front page (56) References JP-A-4-337780 (JP, A) JP-A-57-155571 (JP, A) JP-A-2-163784 (JP, A) JP-A-3-45566 (JP) , U) JP 45-5143 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (4)

(57) [Claims] In a fixing device for fixing an image on a transfer material by heating and pressing the fixing roller, one of the pair of fixing rollers is a heating roller, and the other is a pressing roller. It consists of a thin pipe, and in order to reinforce the strength of both ends of the heating roller and to prevent heat from escaping from both ends, the both ends are directed inward over the entire circumference of both ends of the heating roller. A fixing device comprising a bent portion bent at a substantially right angle . 2. The fixing device according to claim 1, wherein the inner surface of the bent portion for reinforcing the strength and preventing heat from escaping from both ends is provided around the both ends of the heating roller. , The difference between the reflectance of the center inside the heating roller and
A fixing device, wherein the reflectance of the inner surface of the bent portion is 70% or more. 3. A heating device side end of a heating roller according to claim 1, wherein a bending portion for reinforcing strength and preventing heat from escaping from both ends is provided at both ends. Along with providing a long hole in the gear fixing portion, a hole is also provided in the drive gear side, and after fitting the drive gear to the end of the heating roller and aligning the position of the long hole and the hole in the gear side, A fixing device wherein a key is inserted into both holes to fix a driving gear. 4. A fixing device according to claim 1, wherein the heating roller is provided with a bent portion for reinforcing the strength at both ends and for preventing heat from escaping from both ends. A fixing device, wherein a long hole is provided in the gear fixing portion, a detent key is inserted corresponding to the long hole, and the driving gear is stopped via the detent key.