JP2006251068A - Fixing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily support a film-like belt and to satisfactorily heat the film-like belt up to a desired temperature, in a fixing apparatus using the film-like belt as a heating member. <P>SOLUTION: The fixing apparatus includes a pressure roller 1 and a heat roller 2. The heat roller 2 includes; the endless film-like belt 23; a supporting member 22 for guiding the film-like belt 23 so that the inner peripheral surface of the belt 23 may rub the roller 2; a pressure means 4 for pressurizing the film-belt 23 against the supporting member 22; a heat source 21 arranged at the inside of the supporting member 22; and a temperature detecting means 5 for detecting the outer surface temperature of the film-like belt 23 in non-contact with the belt 23. A distance between the film-like belt 23 and the temperature detecting means 5 in the non-contact state is kept constant by the pressure means 4. Thus, the distance between the film-like belt and the temperature detecting means in the non-contact state is kept constant, consequently, the temperature is satisfactorily detected, and the temperature of the film-like belt is controlled to the desired one. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device applied to an image forming apparatus that forms an image by an electrophotographic method such as a copying machine or a printer.

In an image forming apparatus that forms an image by an electrophotographic method, generally, a toner image transferred onto a sheet is fixed on the sheet by heating and pressing. For this reason, the image forming apparatus is conventionally provided with a fixing device that nips and conveys a sheet by a pair of rollers of a pressure roller and a heating roller, and fixes a toner image transferred to the sheet.
By the way, since the toner cannot be melted unless the heating roller has a predetermined fixing temperature, the heating roller must be heated to a predetermined temperature before the fixing device is driven. For this reason, the conventional fixing device has a problem that the preheating time of the heating roller is required and the response at the time of start-up is poor.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 2004-94146 proposes an on-demand fixing device using a film belt instead of a heating roller. The fixing device described in this publication includes a pressure roller, a metal member that forms a fixing nip between the pressure roller, and a film belt disposed so as to pass between the metal member and the pressure roller. And a radiation heat source provided in the inner space of the film belt. In this on-demand fixing device, since the film belt with good heat response is heated quickly by the radiation heat source, the waiting time until the film belt reaches a predetermined temperature is short, and the fixing device functions in a short time. It has the feature of obtaining.
JP 2004-94146 A

  The fixing device described in Patent Document 1 theoretically heats the film belt evenly by a radiant heat source, but in reality, the film belt is difficult to heat evenly. This is because a film-like belt is a belt that does not have a thin regularity, and it is difficult to maintain a portion other than the fixing nip in an arc shape. If the film belt is not arcuate, the distance between the radiation heat source provided in the center of the inner space of the belt and the film belt varies depending on the location, and the heating temperature of the film belt varies depending on the location. For this reason, there has been a problem that it is difficult to uniformly heat the sheet with the film belt.

In addition, there is a problem that even if an attempt is made to heat the film belt to a desired temperature, the control thereof is difficult.
The present invention has been made based on such background art. In a fixing device using a film belt as a heating member, the fixing device can heat the film belt evenly, and can perform stable fixing quickly. The main purpose is to provide

  The present invention also provides a fixing device using a film-like belt, which can favorably support the film-like belt and can heat the film-like belt to a desired temperature. The purpose.

  The invention described in claim 1 for achieving the above object has a pressurizing rotary member (1) and a heating rotary member (2), and nips and conveys the paper (P) between the rotary members. Thus, the fixing device fixes the toner image transferred to the paper (P) to the paper (P), and the heating rotary member (2) is connected to the pressure rotary member (1) at the nip. ) And an endless film belt (23) that is rotated in accordance with the rotation of the nip, and at least the nip shape and the upstream shape of the nip, and the inner peripheral surface of the film belt (23) is slid. A support member (22) for guiding the movement of the film-like belt (23) so as to come into contact; a pressing means (4) for pressing the film-like belt (23) against the support member (22); Arranged inside the support member (22) A heat source (21) for heating the film belt (23) via the support member (22), and an outer surface of the film belt (23) moving along the support member (22) And a temperature detecting means (5) for detecting the temperature in a non-contact manner.

In addition, the alphanumeric characters in parentheses represent corresponding components in the embodiments described later. The same applies hereinafter.
According to the structure of Claim 1, the heat which a heat source emits is given to a support member. The film belt is heated via the support member. The support member is in sliding contact with the inner peripheral surface of the film belt. The support member has a shape for guiding the slidable film belt to the nip. For this reason, while the inner peripheral surface of the film belt is in sliding contact with the support member, the film belt is heated evenly through the support member, and the film belt heated appropriately at the nip is transferred to the sheet. The toner image is melted by heating.

  The film belt is always pressed against the support member by the pressing means. For this reason, the film-like belt is in slidable contact with the support member without sag at least until it is nipped from the pressing means. As a result, the distance between the film belt and the non-contact temperature detecting means is constant, and a favorable temperature detecting means is possible. Therefore, the film belt can be controlled to a desired temperature.

  According to a second aspect of the present invention for achieving the above object, the support member (22) includes a nip forming portion (31) having a substantially linear shape or a slightly concave curve shape in the paper conveying direction, and the above-described support member (22). A guide portion (32) that extends upstream of the nip forming portion (31), has a convex curve in an arc shape, and guides the film belt (23) to the nip forming portion (31). The fixing device according to claim 1, wherein:

According to the second aspect of the present invention, the guide portion is convexly curved in an arc shape, and the arc guide portion is evenly heated by the heat source. For this reason, the film-like belt is heated uniformly and satisfactorily while being in sliding contact with the guide portion.
And since the nip formation part is carrying out the substantially linear shape or the loosely concave shape, a favorable nip can be formed between the rotation members for pressurization. The film belt is moved along with the rotation of the pressurizing rotary member along the nip forming portion, so that the paper on which the toner image is fixed is efficiently transferred while being conveyed along the nip forming portion. Heated and pressurized.

The invention according to claim 3 for achieving the above object is characterized in that the pressing means (4) is an oil application member for applying oil to the outer peripheral surface of the film belt (23) or the film. 3. The fixing device according to claim 1, further comprising a cleaning member for cleaning the outer peripheral surface of the belt (23).
In the configuration of claim 3, the means for pressing the film belt is an oil application member or a cleaning member, so that the function of applying oil to the original film belt or the toner adhered to the film belt is obtained. A function of removing the film and a function of pressing the film belt can be provided at the same time. For this reason, the film-like belt can be slidably contacted with the support member without sagging, and in addition, it can have another function, leading to reduction of members.

According to a fourth aspect of the present invention for achieving the above object, the pressing means (4) includes a contact-type temperature sensor, and the temperature sensor includes the sheet (P) of the film belt (23). 3. The fixing device according to claim 1, wherein a non-sheet-passing area that does not come into contact with the sheet is pressed.
In the structure of Claim 4, in a press means, by providing a contact-type temperature sensor in a contact part with the non-sheet passing part of a film-like belt, the film-like belt which is an original function is pressed to a support member, and a support member In addition to the sliding contact without sagging, the surface temperature of the film belt can be directly detected. Thereby, stable temperature control of a film-like belt can be performed.

  According to the present invention, there is provided a so-called on-demand type fixing device that can control the temperature of the film belt satisfactorily by the pressing means and that can uniformly heat the paper under appropriate temperature control. Can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall schematic view of a fixing device according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the fixing device shown in FIG.
Referring to FIGS. 1 and 2, the fixing device according to this embodiment includes a pressure roller 1 and a heating rotation member 2 as pressure pressing members. The pressure roller 1 and the heating rotary member 2 cooperate to nip the paper P and convey it while heating and pressing. Therefore, the toner image transferred onto the paper P is fixed on the paper P.

The pressure roller 1 may be a general roller conventionally used in a fixing device, and includes a rotating shaft 11 and a roller 12 made of an elastic body that is externally fitted on the peripheral surface of the rotating shaft 11. . A gear 13 is provided at one end of the elastic roller 12, and the pressure roller 1 is driven by applying a driving force from a motor (not shown) to the gear 13.
A feature of this embodiment is that the heating rotary member 2 that forms a nip in cooperation with the pressure roller 1 has a configuration described below.

That is, the heating rotating member 2 includes an endless film-like belt 23, a support member 22 for guiding the movement of the film-like belt 23 so that the inner peripheral surface of the film-like belt 23 is in sliding contact, And a heat source 21 disposed inward.
The support member 22 is formed by bending a thin metal plate such as aluminum or copper. The support member 22 has a hollow, substantially cylindrical shape, and is opposed to the pressure roller 1 and has a substantially straight nip forming portion in the sheet conveyance direction. 31, a non-guide portion 33 connected to the downstream side of the nip forming portion 31, and an arcuate guide portion 32 connecting the upper end of the non-guide portion 33 and the upstream side of the nip forming portion 31. A large number of openings 34 are formed in the non-guide portion 33.

The film-like belt 23 is fitted on the outside of the support member 22 and is in a state where it has an appropriate slack with respect to the outer peripheral surface of the support member 22. The film-like belt is made of, for example, polyimide and has a thickness of about 50 μm.
The heat source 21 is composed of a sheathed heater, for example, and is arranged in the center of the space surrounded by the support member 22.

  In this configuration, when the pressure roller 1 is rotated, the rotating pressure roller 1 is in pressure contact with the nip forming portion 31, and the elastic roller 12 rotates while being pressed and deformed at that portion, so that the nip forming portion is rotated. A linear nip is formed between the elastic roller 31 and the elastic roller 12 in the sheet conveyance direction. Then, the film belt 23 between the nip forming portion 31 and the elastic roller 12 is driven and rotated as the pressure roller 1 rotates.

During the rotational movement of the film belt 23, the film belt 23 guided on the upstream side of the nip forming portion 31, that is, along the outer peripheral surface of the arc guide portion 32, has the guide portion 32 having a semicircular arc shape. Therefore, it is slidably moved while being in contact with the outer peripheral surface of the guide portion 32.
On the other hand, the downstream end of the nip forming portion 31 has a shape bent with a small radius of curvature in a direction away from the pressure roller 1 and is connected to the non-guide portion 33. Therefore, the nip forming portion 31 and the elastic body The film belt 23 that is sandwiched between the rollers 12 and moves following the elastic roller 12 rotates along the peripheral surface of the non-guide portion 33 when further moving from the downstream side of the nip forming portion 31. First, it rotates upward in a state where it floats from the non-guide portion 33, contacts the arcuate guide portion 32 on its upper surface, and moves along the outer peripheral surface of the guide portion 32 as described above.

  When the heat source 21 generates heat while the film belt 23 moves, the support member 22 is warmed by radiant heat. As described above, the support member 22 is a thin member such as a metal having good thermal conductivity. Heat well. Therefore, when the film belt 23 passes through the nip forming portion 31, the film belt 23 has a constant temperature.

As described above, the support member 22 has a fixed shape including the nip forming portion 31, the guide portion 32, and the non-guide portion 33 and is fixed so as not to rotate. It is in a state where a constant appropriate nip is always formed.
Further, since the support member 22 can form the nip forming direction and the curvature thereof in an arbitrary shape, the connecting portion from the downstream side of the nip forming portion 31 to the non-guide portion 33 has a shape advantageous for separating the paper P. Can be formed.

FIG. 3 is a schematic view of an embodiment of another nip forming portion according to the present invention.
In this embodiment, the support member 22 includes a nip forming portion 31 that is slightly concavely curved on the heat source 21 side. As a result, a smaller radius of curvature can be formed at the end of the nip forming portion 31 than when the nip forming portion 31 is substantially linear in the paper conveyance direction shown in FIG. The sheet P can be advantageously separated.

Of the inner peripheral surface of the support member 22, at least the inner peripheral surface of the guide portion 32 is preferably painted black. This is because the black coating allows the support member 22 to absorb the radiant heat from the heat source 21 better and warm it.
Note that black coating may be applied to the entire inner peripheral surface of the support member 22 so as to absorb radiant heat.

4 is a partially cutaway perspective view of the fixing device shown in FIG. 1 when viewed from the non-guide portion side.
Here, the paper P, the heat source 21, and a part of the film belt 23 are omitted in the drawing.
Since a large number of openings 34 are formed in the non-guide portion 33 as shown in the figure, the radiant heat of the heat source 21 is transmitted through the opening 34 to the film belt 23 that rotates without contacting the non-guide portion 33. The film belt 23 can be heated.

By the way, even if the preheating of the film-like belt 23 is uneven, the film-like belt is heated uniformly when it is slidably contacted along the circumferential surface of the guide portion 32 thereafter, so there is no problem.
If the support member 22 can sufficiently support the film belt 23, the entire non-guide portion 33 may be the opening 34, that is, the non-guide portion 33 may be omitted from the support member 22. For the same reason, the shape of the opening 34 does not depend only on the illustrated shape.

With the above configuration, when the film belt 23 is heated and moved along the nip forming portion 31, the heating rotary member 2 can be heated so that the temperature of the film belt 23 can be uniformly heated. be able to.
In this embodiment, in addition to the above configuration, a pressing means 4 for pressing the film belt 23 on the peripheral surface of the support member 22 is further provided. The pressing means 4 is disposed so as to face a region on the upstream side of the guide portion 32 in the support member 22, and presses the film belt 23 against the outer peripheral surface of the guide portion 32. As the pressing means 4, a roller extending in a direction parallel to the axial direction of the support member 22 can be used as shown in FIG. 1. This roller can also be used as an oil application roller for applying oil to the peripheral surface of the film belt 23, for example.

FIG. 5 is a schematic view when the pressing means according to the present invention is used as a cleaning member.
As shown in the drawing, the pressing means described above may use a cleaning member 41 for cleaning the outer peripheral surface of the film belt 23 instead of the roller.
By using the pressing means 4, the film belt 23 can be reliably brought into contact with the outer peripheral surface of the guide portion 32 in the support member 22, and the film is formed along the outer peripheral surface of the guide portion 32 on the downstream side from the pressing means 4. The belt 23 is slid and moved.

  Further, a non-contact temperature sensor 5 is provided on the downstream side of the position pressed by the pressing means 4. Since the non-contact temperature sensor 5 faces the position where the film-like belt 23 moves in sliding contact with the support member 22 reliably, the distance between the film-like belt 23 and the non-contact temperature sensor 5 is kept constant. Therefore, the non-contact temperature sensor 5 can perform good temperature detection. Therefore, the temperature of the film belt 23 can be accurately grasped, and the temperature of the film belt 23 can be controlled to be a predetermined temperature.

Note that the pressing means 4 of the present invention may be provided with a contact-type temperature sensor at a contact portion with the non-sheet passing portion of the film belt 23. By providing the pressing means 4 in contact with the film belt 23 also with a temperature detection means, the temperature of the film belt surface can be directly detected. In this case, it is not necessary to install the non-contact temperature sensor 5, and the number of members can be reduced.
With the above configuration, even if a thin film belt 23 is used, the support member 22 can maintain it satisfactorily. As a result, the film-like belt 23 always maintains the shape in sliding contact with the guide portion 32 on the support member 22, so that the film-like belt 23 can be stably rotated without causing blurring, and thus can cope with higher speeds. it can.

In addition, the guide portion 32 on the support member 22 is formed at a position where an arc centering on the heat source 21 is drawn. Thereby, since the guide part 32 can be arrange | positioned on the periphery centering on the heat source 21, the guide part 32 can transmit the radiant heat from the heat source 21 uniformly.
Further, the film-like belt 23 receives a tension from the pressurizing rotary member 1 and always takes a shape in sliding contact with the guide portion 32 on the support member 22. Thereby, the film-like belt 23 can receive the heat from the guide part 32 evenly.

An opening 34 is provided in the non-guide portion 33 of the support member 22. Thereby, the film-like belt 23 can receive radiant heat directly from the heat source 21, and can prompt the start-up of the copying machine.
Furthermore, the distance between the film belt 23 and the non-contact temperature sensor 5 can be kept constant. Thereby, the surface temperature of the film-like belt 23 can be accurately detected, and the optimum temperature control of the film-like belt 23 can be performed. By preventing unnecessary heating, the power consumption of the copying machine can be minimized.

Accordingly, it is possible to provide a so-called on-demand type fixing device that can reduce the waiting time by quickly heating the film belt through the support member by the heat source and can perform the heating control of the paper satisfactorily. it can.
In the above description, the fixing device of a so-called monochrome copying machine has been described as an example. However, the fixing device of the present invention can also be applied to a fixing device installed in an image forming measure such as a color copying machine or a color printer.

  In addition, various design changes can be made within the scope of the matters described in the claims.

1 is an overall schematic diagram of a fixing device according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the fixing device shown in FIG. 1. It is the schematic of embodiment of the other nip formation part concerning this invention. FIG. 2 is a partially cutaway perspective view of the fixing device shown in FIG. 1 when viewed from the non-guide portion side. It is the schematic when the press means concerning this invention is made into the cleaning member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating member for pressure 11 Rotating shaft 12 Elastic roller 13 Gear 2 Rotating member for heating 21 Heat source 22 Support member 23 Film-like belt 31 Nip forming part 32 Guide part 33 Non-guide part 34 Opening 4 Pressing means 41 Cleaning member 5 Non-contact Temperature sensor P Paper

Claims (4)

A fixing device that includes a pressure rotating member and a heating rotating member, and fixes the toner image transferred to the paper to the paper by conveying the paper with the paper nipped between the rotating members;
The heating rotating member is
An endless film belt which is rotated and moved in accordance with the rotation of the pressing rotary member at the nip;
A support member for guiding the movement of the film belt so as to form at least the shape of the nip and the shape of the upstream side of the nip, and the inner peripheral surface of the film belt is in sliding contact;
Pressing means for pressing the film belt against the support member;
A heat source disposed inside the support member for heating the film belt via the support member;
And a temperature detecting means for detecting the outer surface temperature of the film belt moving along the support member in a non-contact manner. The support member is
A nip forming section that is substantially linear or slightly concave in the paper transport direction;
The fixing device according to claim 1, further comprising a guide portion that extends upstream of the nip forming portion, has a convex curve in an arc shape, and guides the film belt to the nip forming portion. apparatus.   The said pressing means includes an oil application member for applying oil to an outer peripheral surface of the film belt or a cleaning member for cleaning the outer peripheral surface of the film belt. Item 3. The fixing device according to Item 2. The said pressing means contains a contact-type temperature sensor, The said temperature sensor is pressing the non-sheet passing area | region which does not contact the said sheet | seat of the said film-like belt, The Claim 1 or Claim 2 characterized by the above-mentioned. Fixing device.

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