JPH086416A - Fixing device for image forming device - Google Patents

Abstract

PURPOSE:To easily arrange a heater body at the inside diameter part of the heating roller of a fixing device. CONSTITUTION:The bearing parts of both left and right ends of the cylindrical heating roller 16 and a pressure roller are supported by the left and the right supporting side plates 35a and 35a of a lower case 35. On the other hand, a pair of left and right holders 46 and 46 made of a metallic leaf spring is fixed to the lower surface of the top plate 36a of an upper case 36 covering the upper part of the roller 16. Besides, the electrode terminals 43a and 43a of both left and right sides of the bar-like heater body 43 inserted in the inside diameter of the roller 16 are supported at the joining parts 46a and 46a of both holders 46 and 46 whose lower ends are faced inside. Then, power is supplied. By setting the joining parts 46a and 46a so as to be positioned in aperture parts 55 and 55 formed at both left and right cover parts 36a and 36a extended downward from both left and right ends of the top plate 36a of the upper case 36, the heater body 43 is inserted and loaded from the aperture parts 55 without detaching the upper case 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a laser printer, a copying machine, a facsimile machine, and more particularly, to fixing a toner image transferred onto a recording medium such as paper. The present invention relates to the structure of the fixing device.

[0002]

2. Description of the Related Art Conventionally, in a fixing method based on a contact heating method using a pair of a heating roller and a pressing roller, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-100059, the outer side of the pressing roller is an elastic layer. There is known a configuration in which a cylindrical heating roller having an outer periphery of a cylindrical aluminum cored bar as an elastic layer is arranged, and a heat source including a rod-shaped (cylindrical) halogen lamp is arranged in the cylinder.

In this type of fixing device, since it is necessary to rotate the heating roller and the pressing roller, one of the rollers is rotatably driven, while the halogen as a heat source is used. Since the lamp raises the temperature of the peripheral surface of the heating roller to a uniform temperature, it is arranged in parallel so as to coincide with the axis of the heating roller, and both ends of the halogen lamp are in a non-rotating state regardless of the rotating heating roller. In general, power is supplied by supporting the electrodes and connecting power supply terminals to the electrode parts at both ends of the halogen lamp.

Further, in order to prevent a user from touching the heating roller and causing a burn when a paper jam occurs, the fixing device covers at least the outer periphery of the heating roller.
Is known to be provided.

[0005]

However, since the halogen lamp has a life such as disconnection due to long-term use, it is necessary to replace the halogen lamp.
At that time, conventionally, since the work of removing the case (cover), disassembling the supporting member of the halogen lamp, and removing the power supply terminal has been performed, the replacement work is troublesome and various tools are required. There was a problem.

The present invention has been made to solve these technical problems, and an object of the present invention is to provide a fixing device for an image forming apparatus in which replacement work of a rod-shaped heater body as a heat source is easy. It is a thing.

[0007]

To achieve the above object, the invention according to claim 1 is a recording medium on which a toner image is transferred by a heating roller and a pressing roller which rotate around a substantially horizontal rotation axis. A fixing device for an image forming apparatus configured to apply heat and pressure to fix a toner image to a side plate of a main body case that covers outer circumferences of a heating roller and a pressing roller. An opening for inserting a rod-shaped heater body to be inserted into the inner diameter portion of the roller is formed, and a pair of supports for supporting the electrode portions formed at both longitudinal ends of the heater body and supplying power in the main body case. Means is provided, and at least one joint with the electrode portion of both supporting means is positioned within the opening area of the opening, and at least one supporting means is configured to be elastically displaceable in the axial direction of the heater body. One in which the.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the fixing device of the image forming apparatus supports the main body case on the bearing portions at the left and right ends of the heating roller and the pressing roller, respectively. A lower case and an upper case that covers the upper surface of the heating roller and is attached to the lower case,
The left and right side plates of the upper case are formed with openings for inserting a rod-shaped heater body to be inserted into the inner diameter of the cylindrical heating roller, and the pair of left and right supporting means are attached to the inner surface of the upper case.

[0009]

Next, an embodiment of the present invention will be described. FIG. 1 is a schematic side sectional view of a laser beam printer 1 as an image forming apparatus, and FIG. 2 is a vertical sectional view of a fixing device. In the printer 1 of this embodiment, a paper feed cassette 3 as a paper feed unit is detachably attached to a lower portion of a main body case 2, and recording sheets stacked in the paper feed cassette 3 by a plurality of paper feed rollers 4 and the like. The paper P as a medium is separated one by one, and the image forming unit 7 and the transfer roller 9 on the transfer unit base 8 are separated via the paper midway guide plate 5 and the feeding roller pair 6.
Sent between and.

The image forming unit 7 includes a photosensitive drum 10.
A developing device unit 11 including a toner tank and a developing roller 12, and a charging device 13 including a charging roller,
A cleaning (not shown) device and the like are housed in a case as one kit to form a single unit. A scanner unit 22 including a laser emitting section 23, a lens 24, a reflecting mirror 25, and the like is arranged above the image forming unit 7, and below the transfer unit table 8 the charging device 13 and the transfer roller 9 are arranged. A high voltage substrate 26 for applying a high voltage is arranged, and a control substrate 27 is arranged below the fixing device 15.

The surface of the photosensitive drum 10 precharged by the charging device 13 is irradiated with light emitted from the scanner unit 22 according to image data transmitted from an external device such as a host computer (not shown). The electrostatic latent image is formed on the surface of the photoconductor drum 10, and then the developing roller 12 is rotated to supply the charged powdery toner to visualize the latent image. After that, the toner image is transferred onto the paper P supplied to the transfer site between the photoconductor drum 10 and the transfer roller 9. Next, the paper P that is conveyed by sliding on the fin-shaped passage guide member 32 on the surface side (upper side) of the transfer unit base 8 made of synthetic resin having electric insulation is the heating roller 1 in the fixing device 15.
The toner image is fixed on the paper P by passing heat and pressure to the transferred toner image after passing between the roller 6 and the pressing roller 17 (fixing portion). Thereafter, the paper P is discharged to the paper tray 21 on the upper surface of the main body case 2 via the paper discharge guide plate 18, the intermediate roller pair 19, and the paper discharge roller pair 20.

Next, the structure of the fixing device 15 is shown in FIG.
As described in detail with reference to FIG. 6, the case of the fixing device 15 is composed of a pair of upper and lower cases 36 and 35 which cover the heating roller 16 and the pressing roller 17 from above and below, as shown in FIG. ing. In the embodiment, the lower case 35 having a pair of left and right supporting side plates 35a, 35a for supporting the bearings at the left and right ends of the heating roller 16 and the pressing roller 17, and the upper part of the heating roller 16 are covered.
In addition, the upper case 36 is detachable from the lower case 35, and the upper and lower cases 36 and 35 are epoxy resin, phenol resin, urea resin, melamine resin, and AB, respectively.
An electrically insulating and heat resistant synthetic resin such as S resin is integrally formed by injection molding.

As shown in FIGS. 2 and 5, bearings 37 (only one of which is shown in FIG. 3) on both left and right ends of the lower pressing roller 17 are provided on the pair of left and right supporting side plates 35a, 35a of the lower case 35. A long groove 38 that guides vertically and a large-diameter bearing hole 40 into which the substantially cylindrical bearing members 39, 39 of the heating roller 16 are fitted are continuously formed.
By pushing 7 upward with a coil spring (not shown), the upper surface of the pressing roller 17 is pressed against the lower surface of the heating roller 16.

As shown in FIG. 5, the left and right ends of the upstream guide plate 41 and the downstream guide plate 42 that sandwich the front and rear portions of the pressing roller 17 and extend substantially parallel to the axis thereof are as shown in FIG.
The pair of left and right supporting side plates 35a, 35a are integrally connected. As shown in FIG. 5, the plurality of fin portions 41a of the upstream guide plate 41 are erected at appropriate intervals in the axial direction of the pressing roller 17, and the upper end edges of each fin portion 41a are set as shown in FIG. The front end (upstream side of the sheet P in the conveying direction) is low and is inclined so as to be closer to the fixing portion A as it approaches the peripheral surface of the pressing roller 17. Similarly, the plurality of fin portions 42a in the downstream guide plate 42
Are erected at appropriate intervals in the axial direction of the pressing roller 17,
The upper edge of each fin portion 44a is at a lower position where the front end is closer to the fixing portion A, and as the distance from the pressing roller 17 increases (the paper P
(Downstream side in the transport direction of), the heating roller 16 is inclined so as to be at substantially the same height as the upper surface of the heating roller 16.

The heating roller 16 has an elastic layer having rubber elasticity such as silicone resin or silicon resin on the outer periphery of a cylindrical portion made of a material having high thermal conductivity such as aluminum, and a releasable resin surface layer (polyester) on the surface thereof. Tetrafluoroethylene, perfluoroalkoxy-chitrafluoroethylene copolymer, etc.). The release resin surface layer softens the toner fixed on the paper P at the time of fixing to the heated roller 16 again.
It is possible to prevent a so-called offset phenomenon that is transferred to the surface of the next paper P via the sheet.

A linear (cylindrical) heater body 43 such as a halogen lamp as a heat source for keeping the circumferential surface of the cylindrical heating roller 16 at a uniform temperature (for example, 170 ° C. to 200 ° C.). 2, is longer than the length of the heating roller 16, and the left and right end portions of the heater body 43 project outward from the left and right end portions of the heating roller 16 by an appropriate dimension. It is electrically connected to the electrode terminals 43a, 43a at both left and right end portions of 43 and is supported so as to coincide with the axis of the heating roller 16.

As shown in FIG. 5, the upper case 36 has a linear (cylindrical) heater body 4 such as a halogen lamp protruding outward from the inner diameter of the heating roller 16.
Downward side cover parts 36b, 3 that cover the left and right end parts of 3
6b are integrally provided so as to extend downward from both left and right ends of the top plate 36a. As shown in FIG. 2, the pair of holders 46, 46 serving as a support means for electrically connecting and supporting the electrode terminals 43a, 43a at the left and right ends of the heater body 43 as shown in FIG. It is made of a metal plate having a spring elasticity formed in an L shape in the horizontal direction when viewed, and the base ends of the horizontal portions of both holders 46, 46 are connected to the upper case 36.
It is fixed by screws 47 to the lower surface of the top plate 36a. The left and right holders 46, 46 have their lower ends bent inwardly to support the joint portions 46a, 46a by elastically pressing and contacting the concave end portions of the left and right electrode terminals 43a, 43a of the heater body 43. Yes (see FIGS. 2 and 3).

On the other hand, at the lower ends of the left and right both side cover portions 36b, 36b of the upper case 36, as shown in FIG.
Are formed. The openings 55 and the holders 4
As for the positional relationship between the joint portion 46 and the joint portion 46 a, as shown in FIGS. 2 and 6, the joint portion 46 is located within the opening area portion of the opening portion 55.
It is set so that a is located.

It should be noted that the wiring 60 is connected to the power feeding portion such as the screw 47 exposed on the upper surface of the top plate 36a of the upper case 36.
60, and connect the wires 60, 60 to the control board 27.
The electric power is supplied to the heater body 43 by connecting to the electric power circuit 61 provided in the above. Further, in the upper case 36, a plurality of heat insulating walls 44 and 45 facing the rear end of the adjacent image forming unit 7 face downward from the top plate 36a of the upper case 36 along the axis of the heating roller 16. And is integrally formed so as to cover at least the upper half of the circumference of the heating roller 16 (see FIG. 4). As another embodiment, the number of heat insulating walls may be three or more.
It is preferable to provide an air reservoir 56 that is surrounded by a.

Further, on the downstream side of the upper case 36 in the conveying direction of the paper P, a paper peeling guide member 48 is provided on the top plate 36a.
Downwardly, the lower end edge portion 48a is integrally provided on the rear peripheral surface of the heating roller 16 so as to be close to the heating roller 16 with a gap of about 0.2 mm to 0.5 mm (see FIG. 4). The sheet peeling guide member 48 is parallel to the axis of the heating roller 16 and has substantially the same length as the heating roller 16.

Then, as shown in FIG.
On the lower surface of the top plate 36a of the sheet peeling guide member 48, a rib 50 having a lower end edge continuous with the sheet peeling guide member 48 and curved in an upward convex shape is provided so as to project downward at a plurality of positions at appropriate intervals in the axial direction of the heating roller 6. ing. A plurality of play rollers 51 having a lower peripheral surface below the lower end edges of the ribs 50 are rotatably arranged on a shaft 52 on the downstream side of the upper case 36 in the conveyance direction of the paper P.

With these configurations, the leading edge of the paper P curled substantially along the circumferential surface of the heating roller 16 at the time of fixing is peeled off at the lower end edge portion 48a of the paper peeling guide member 48,
Next, the leading edge of the sheet P is slidably contacted with the lower edge of the rib 50 and is fed to the downstream side of the conveyance. When the leading edge of the paper P is nipped by the intermediate roller pair 19 and fed, the heating roller 16
The upper surface (the surface on which the toner has been fixed) of the paper P, which is curved in the same direction as the circumferential surface of, does not slidably contact the lower edge of the upwardly convex rib 50. Moreover, the play roller 51 that rotates freely
The toner on the upper surface of the paper P is not peeled off after being fixed because it is smoothly fed along the circumferential surface of the sheet P, and the toner does not adhere to the edge of the rib 50 or the circumferential surface of the play roller 51, so that the image quality is not deteriorated. is there.

As described above, the lower case 35 and the upper case 36 which are divided into two parts are assembled with the pressing roller 17 and the heating roller 16 in advance in the lower case 35, while the upper case 3
After attaching the play roller 51 to 6, the top plate 36a of the upper case 36 is placed on the upper end surfaces of the pair of left and right supporting side plates 35a, 35a of the lower case 35 to cover the supporting side plate 35.
female screw portions 5 formed at the upper ends of a and 35a
3, the upper case 36 may be fastened with screws 54 (see FIG. 5).

Thereafter, the rod-shaped heater body 43 is inserted into the inner diameter portion of the heating roller 16 from one of the openings 55 of the left and right side cover portions 36b, 36b of the upper case 36, and the concave end surface of one electrode terminal 43a of the heater body 43 is inserted. The portion is pressed against the joint portion 46a of the one holder 46 along the axial direction of the heater body 43, and is held so that the electrode terminal 43a does not come off from the joint portion 46a with the finger 62 inserted from the other opening 55. (See Figure 6). Then, as shown in FIG. 7, the fingers 63 of one hand elastically move the holder 46 located inside the one opening 55 away from the electrode terminal 43a (the direction indicated by the chain double-dashed line in FIG. 2). The holder 63, the joint portion 46a of the holder 46 is fitted into the concave end surface portion of the electrode terminal 43a, and then the finger 63 is removed from the holder 46. Accordingly, the elastic force of the pair of holders 46, 46 themselves can suspend and support the electrode terminals 43a, 43a of the heater body 43 in the axial direction by the joint portions 46a, 46a thereof. .

When the heater body 43 is replaced due to a wire breakage, a new heater 43 is used without removing the upper case 36 from the lower case 35 in the same manner as described above.
Can be exchanged for. In addition, the fingers 62,
In order to make it easier to hook 63, as shown in FIG. 8, a protrusion 64 may be provided on the vertical portion of the holder 46 or the like. In addition,
As another embodiment, as shown in FIG. 9, holders 65 and 65 having base ends fixed to the outer surfaces of the left and right support side plates 35a and 35a of the lower case 35 have a joint portion 65a in which the lower ends are bent inward (see FIG. It is also possible to support both the left and right electrode terminals 43a, 43a of the heater body 43 by means of only one (9 in FIG. 9). Since the upper case 36 only needs to be covered after completing the assembling of the necessary parts, the assembling work is further simplified. Further, when replacing the heater body 43, the heater body
There is an effect that it is possible to insert and execute and to execute it by removing the upper case 36.

Further, the driven gear 57 is fixed on the outer peripheral surface on one side of the heating roller 16 so that the rotational force is transmitted from a drive side gear (not shown) facing the front space of the upper case 36. The fixing device 15 thus assembled
Is attached adjacent to the rear end side of the image forming unit 7, heat radiated from the heating roller 16, especially radiant heat,
The upper case 36 is shielded by a plurality of heat insulating walls 44 and 45. Further, as shown in FIG. 4, by forming the air pocket 56 between the plurality of heat insulating walls 44, 45 and the top plate 36a, the heat insulating effect can be improved in the presence of air which is a poor heat conductor. The heat radiation and heat convection in the direction of the image forming unit 7 can be effectively eliminated, the toner in the image forming unit 7 can be prevented from softening, and the image quality does not deteriorate even when the printer 1 is operated for a long time. .

Although the heating roller 16 is arranged on the upper side and the pressing roller 17 is arranged on the lower side in the above embodiment, instead of this, the heating roller 16 is attached to the lower case 35 and the upper case 36. In the embodiment in which the pressing roller 17 is attached to the holder, a holder (not shown) made of a spring metal plate for supporting the left and right electrode terminals 43a, 43a of the heater body 43 is provided.
The heating roller 16 is mounted on the outer surface of the support side plate 35a in the lower case 35 for rotatably supporting the outer peripheral end portion thereof, and the pressing roller 17 is supported by the upper case 36.
Further, the openings 55 may be formed in the left and right cover portions 36b, 36b of the upper case 36 as in the above-described embodiment.

According to each of the above embodiments, the supporting means is a holder made of metal and having elasticity, so that it supports the heater body 43 non-rotatably and also has a function as a power feeding means. The work of attaching and detaching the body 43 becomes extremely easy. Moreover, since the supporting means is attached to the upper case 36 or the lower case 35 and is arranged at least at a position covered by the upper case 36, there is no possibility that the user or the like will be electrocuted when the power is supplied to the heater body 43. It has an effect.

Needless to say, the present invention can be applied to a fixing device in an electrostatic electrophotographic image forming apparatus such as a facsimile or a copying machine.

[0030]

As described above, claim 1
The fixing device of the image forming apparatus according to the invention described above applies heat and pressure to a recording medium such as a sheet on which a toner image is transferred by a heating roller and a pressing roller that rotate around a substantially horizontal axis of rotation of the toner. An opening for inserting a rod-shaped heater body to be inserted into the inner diameter of the cylindrical heating roller is formed on the side plate of the main body case configured to fix the image and covering the outer circumference of the heating roller and the pressing roller. , A pair of supporting means for supporting and supplying power to the electrode portions formed at both ends of the heater body in the longitudinal direction are provided in the main body case, and at least one joint portion with the electrode portions of both supporting means is provided. Is arranged so as to be positioned within the opening area of the opening, and at least one of the supporting means is configured to be elastically displaceable in the axial direction of the heater body.

Therefore, when the heater body inserted from the side opening of the case body is mounted by the supporting means, the supporting means also has a function of supporting the heater body in a non-rotational manner and supplying power. In addition, even when the heater body is attached and detached, there is an effect that the attachment and detachment work is extremely easy because no additional tool is required. Moreover, since the supporting means is arranged in the main body case, there is an effect that there is no possibility that the user or the like will get an electric shock when power is supplied to the heater body.

Further, in the fixing device of the image forming apparatus according to the second aspect of the present invention, in addition to the constitution of the first aspect, a main body case is provided.
It consists of a lower case that supports the bearings at the left and right ends of the heating roller and the pressing roller, and an upper case that covers the upper surface of the heating roller and is attached to the lower case. An opening for inserting a rod-shaped heater body to be inserted into the inner diameter of a rectangular heating roller is formed, and a pair of left and right supporting means is attached to the inner surface of the upper case.

Therefore, the same action and effect as the invention according to the first aspect can be obtained, and the upper and lower cases can be divided to facilitate the disassembling work of the fixing device. Further, since the left and right side plate portions of the upper case cover both the left and right outer surfaces of the lower case, there is an effect that the user does not touch the rotating portion of the roller and is safe.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a laser printer.

FIG. 2 is a vertical cross-sectional view of a fixing device.

FIG. 3 is a side view taken along the line III-III of FIG.

4 is a sectional view taken along the line IV-IV in FIG.

FIG. 5 is a perspective view of a lower case and an upper case.

FIG. 6 is a perspective view showing the attachment / detachment work of the heater body.

FIG. 7 is a cross-sectional view showing the attachment / detachment work of the heater body.

FIG. 8 is a cross-sectional view of essential parts showing another embodiment of the holder as the supporting means.

FIG. 9 is a longitudinal cross-sectional view of a main part showing still another embodiment of the holder as the supporting means.

[Explanation of symbols]

 1 Printer 2 Main Body Case 7 Image Forming Unit 8 Transfer Unit Stand 10 Photosensitive Drum 15 Fixing Device 16 Heating Roller 17 Pressing Roller 35 Lower Case 35a Support Side Plate 36 Upper Case 36a Top Plate 36b Side Cover 43 Heater 43a Electrode Terminal 46, 65 Holder 46a, 65a Joint part 55 Opening part

Claims (2)

[Claims] 1. An image forming apparatus configured to apply heat and pressure to a recording medium on which a toner image is transferred by a heating roller and a pressing roller that rotate around a substantially horizontal rotation axis to fix the toner image. In the fixing device of the apparatus, an opening for inserting a rod-shaped heater body to be inserted into an inner diameter portion of a cylindrical heating roller is formed in a side plate of a main body case that covers outer circumferences of the heating roller and the pressing roller, In the case, a pair of supporting means for supporting and supplying power to the electrode portions formed at both ends in the longitudinal direction of the heater body is provided, and at least one joint portion of the both supporting means with the electrode portion is provided. Is located within the opening area of the opening, and at least one of the supporting means is configured to be elastically displaceable in the axial direction of the heater body. 2. The main body case is composed of a lower case that supports bearing portions at both left and right ends of the heating roller and the pressing roller, and an upper case that covers an upper surface of the heating roller and is attached to the lower case. The left and right side plates of the upper case are formed with openings for inserting a rod-shaped heater body to be inserted into the inner diameter portion of the cylindrical heating roller, and the pair of left and right supporting means is attached to the inner surface of the upper case. The fixing device of the image forming apparatus according to claim 1.