JP4911764B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device, and more particularly to a fixing device that switches from a pressing state of a heating belt to an elastic rotating body to a non-pressing state when an abnormality occurs.

In an image forming apparatus such as a copying machine or a facsimile, a toner image formed on the surface of a photosensitive drum is transferred onto a transfer sheet, and the toner is fixed onto the transfer sheet by a fixing device. The fixing device includes a heating roller that heats and melts the toner on the transfer paper, and an elastic rotating body such as a pressure roller that presses and contacts the heating roller to fix the toner on the transfer paper. When a so-called roller is used as the heating roller, a considerable warm-up time is required until the roller reaches the fixing temperature. Therefore, there is a heating belt that can shorten the warm-up time. It has come to be used.

This heating belt, especially a belt that has been thinned to shorten the warm-up time, has a lower strength than the heating roller, so care must be taken when handling it. For example, normal operation can be performed by releasing the pressure without causing the user to touch the heating belt directly so that the user does not touch the heating belt and tear when an abnormality such as paper jam or image rubbing due to belt deformation occurs. Process is performed.
In order to release the pressure, for example, a method of moving the heating belt and mechanically separating the heating belt and the pressure roller is employed. Specifically, the heating belt includes a movable block that supports the heating belt and a heating source and can move in the vertical direction. The heating belt and the pressure roller are moved by moving the movable block in the upward direction. Has been proposed (see Patent Document 1 below).

  However, in the above-described separation method, the heating body is disposed at the inside of the heating belt where the heating belt and the elastic rotating body are in contact with each other, so that the outer peripheral surface of the heating belt is added even when the contact pressure is weakened. In contact with the pressure roller. For this reason, when the belt is cooled at the time of separation, the contraction rate of the belt is different between a portion that is in contact with the pressure roller and a portion that is not in contact. In particular, when a method of heating the belt using radiant heat is adopted, the contraction rate differs greatly, and therefore the belt is deformed.

JP-A-6-19344

  The present invention has been made to solve the above-described problems of the prior art, and is capable of releasing the pressure contact state between the heating belt and the pressure roller when an abnormality occurs and the like. It is an object of the present invention to provide a fixing device that can be uniformly contracted to prevent deformation.

According to a first aspect of the present invention, in the fixing device for fixing the toner on the transfer paper, the heating belt heats the heating belt. A heating source, a holding means for pressing the heating belt and the elastic rotating body with an appropriate nip width, and a pressing means for pressing the heating belt against the elastic rotating body via the holding means. , the holding means comprises a side along the heating belt with along the heating belt and the opposite side holding member flat portion at the nip center portion is formed in the surface of the corresponding to the nip width, said plane of said retention member It consists of a plate-shaped reinforcing member that is in contact with the part at a substantially right angle,
When an abnormality occurs, the pressing means switches from a pressing state to a non-pressing state, the holding member of the holding means moves away from the heating belt portion on the side in pressure contact with the elastic rotating body, and the reinforcing member contacts the holding member. The present invention relates to a fixing device in which a heating belt portion on the opposite side is pushed at an end opposite to the side so that the heating belt and the elastic rotating body are not in contact with each other.

  The invention according to claim 2 relates to the fixing device according to claim 1, wherein the heating source is a heat source that generates radiant heat.

The invention according to claim 3, before Symbol pressing means includes a pressing member (pressing spring) for biasing the reinforcing member to the holding member side, and the pressure cam for switching the biasing and its release of the pressing member, It consists of a release member (release spring) that urges the reinforcement member in a direction opposite to the holding member. When in the pressed state, the press member applies the reinforcement member toward the elastic rotating body (pressure roller). 3. The fixing device according to claim 1, wherein in the non-pressing state, the pressing member releases the urging force of the pressing member, and only the releasing member is urged.

  The invention according to claim 4 comprises an abnormality detection sensor for detecting the occurrence of an abnormality, and a control unit for receiving detection information of the abnormality detection sensor and controlling the pressure cam. 3. The fixing device according to any one of 3 above.

  The invention according to claim 5 is characterized in that the reinforcing member is a portion in contact with the heating belt, and a convex portion is provided in a part of the rotation direction of the heating belt. The present invention relates to any one of the fixing devices.

According to the first aspect of the present invention, the heating belt includes a heating source, an elastic rotating body (pressure roller), and a holding unit for pressing the elastic rotating body (pressure roller) with an appropriate nip width. , and a pressing means for pressing the heating belt to the elastic rotating member (pressure roller) via the holding means, said holding means comprises a side along the heating belt with along the heating belt in correspondence with the nip width It consists of a holding member with a flat surface formed at the center of the nip on the opposite side and a plate-shaped reinforcing member that is in contact with the flat surface of the holding member at a substantially right angle. The state is switched from the non-pressed state, the holding member of the holding means is separated from the heating belt portion on the side in contact with the elastic rotating body (pressure roller), and the end opposite to the side on which the reinforcing member contacts the holding member heating belt portion on the opposite side parts The heating belt and the elastic rotating body (pressure roller) are completely separated by pressing, so that when the abnormality occurs, the pressure contact between the heating belt and the elastic rotating body (pressure roller) can be released to correct the abnormality. When the heating belt is cooled at the time of separation, there is no portion that contacts the elastic rotating body (pressure roller), so that the heating belt can be uniformly contracted to prevent deformation.

  According to the second aspect of the present invention, even when the heating source is a heat source that generates radiant heat, the contraction rate of the heating belt between the portion where the heating belt is in contact with the pressure roller and the portion where it is not in contact is large. You can avoid different things.

According to the invention of claim 3, the pressing means includes a pressing member for urging the reinforcing member to the holding member side (pressure spring), pressurization switch biasing and the release thereof and the pressing member (pressing spring) Since the cam and the release member that urges the reinforcing member in the direction opposite to the holding member (release spring) are included, the pressed state and the non-pressed state can be switched with a simple configuration such as a spring or a cam.

  According to the invention of claim 4, since the abnormality detection sensor and the control unit for receiving the abnormality detection information and controlling the pressure cam are provided, the pressure cam is immediately switched to the non-pressed state when an abnormality occurs. It is possible to respond to abnormalities quickly.

  According to the fifth aspect of the present invention, the reinforcing member is a portion that comes into contact with the heating belt, and since the convex portion is provided in a part of the heating belt in the rotation axis direction, the reinforcing member is heated by the heating source to a certain extent. The portion of the reinforcing member that is in contact with the heating belt can be reduced, and the portion where the difference in belt contraction rate from the portion that is not in contact slightly occurs can be suppressed as much as possible. Therefore, the deformation of the heating belt due to the difference in belt contraction rate can be prevented more reliably.

Hereinafter, a preferred embodiment of a fixing device according to the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing a configuration example of an embodiment of a fixing device according to the present invention. FIG. 2 is a left side view schematically showing the configuration of the main part of the fixing device shown in FIG. 1, and shows a pressed state. FIG. 3 is a left side view similar to FIG. 2 and shows a non-pressed state.
The fixing device (1) according to the present invention includes a heating belt (2) that heats and melts the toner (23) on the transfer paper (22), and the transfer paper (22) that is pressed against the heating belt (2). A pressure roller (3) for conveying and fixing the toner (23) on the transfer paper (22).

  The heating belt (2) has two heating sources (4) for heating the heating belt (2), and a holding for pressing the heating belt (2) and the pressure roller (3) with an appropriate nip width. Means (5) and pressing means (6) for pressing the heating belt (2) against the pressure roller (3) via the holding means (5) are provided.

The holding means (5) is provided along the inner surface of the heating belt (2) corresponding to the nip width of the nip portion (7) formed by the heating belt (2) being pressed against the pressure roller (3). The holding member (5a) and the reinforcing member (5b) in contact with the holding member (5a) at a substantially right angle.
The pressing means (6) includes a pressing spring (6a) that urges the reinforcing member (5b) toward the holding member (5a), and a pressure cam (6b) that switches between urging and releasing the pressing spring (6a). ) And a release spring (6c) that urges the reinforcing member (5b) in the direction opposite to the holding member (5a).

Further, the fixing device (1) includes an abnormality detection sensor (8) for detecting occurrence of an abnormality such as a paper jam in the apparatus, and a pressure roller (2) of the heating belt (2) by rotating the pressure cam (6b). 3) a pressure motor (9) that switches between a pressed state and a non-pressed state, and a control unit (9) that acquires detection information from the abnormality detection sensor (8) and controls the rotation of the pressure motor (9). It has.
Further, as shown in FIG. 2, the fixing device (1) is provided with an insertion guide (24) for introducing the transfer paper (22) onto which the toner (23) is transferred into the nip portion (7). Although the insertion guide (24) is omitted in FIG. 1, the transfer paper (22) is conveyed from the near side to the back side in the direction substantially perpendicular to the paper surface of FIG.

In the present embodiment, the pressure roller (3) is shown as an example of the elastic rotator, but a pressure belt can also be used, and similar effects can be achieved.
The pressure roller (3), the pressure belt, and the heating belt (2) are not particularly limited in thickness and material, and can be configured with a conventionally known thickness and material.

The reinforcing member (5b) is not particularly limited as long as the urging force by the pressing spring (6a) can be reliably transmitted to the holding member (5a). For example, stainless steel can be exemplified. The holding member (5a) only needs to be able to form an appropriate nip portion (7) by receiving the pressing force from the reinforcing member (5b), and is preferably somewhat elastic. A phosphor bronze plate can be exemplified.
Further, as the pressing spring (6a) and the release spring (6c), it is also possible to use an elastic body other than the coiled spring as illustrated. The pressure cam (6b) is not particularly limited as long as it is a conventionally known cam structure capable of switching between a pressed state and a non-pressed state.
In the illustrated example, the heating source (4) is provided with two heat sources that generate radiant heat. However, the heating source (4) is not necessarily limited to this. For example, the heating source (4) is for heating the air in the heating belt (2). It is possible even if it exists.

Here, the holding means (5) characteristic of the fixing device (1) of the present embodiment will be specifically described.
The holding means (5) is composed of the holding member (5a) and the reinforcing member (5b) as described above, and the plate-like reinforcing member (5b) is interposed between the two cylindrical heating sources (4). , Arranged in non-contact with these. The reinforcing member (5b) is disposed so that its width (short side) direction is substantially vertical, and the heating source (4) is interlocked with the movement of the heating belt (2) and the holding means (5) by a fixing member (not shown). Therefore, even if the biasing force of the pressing spring (6a) is released, the reinforcing member (5b) can move upward without contacting the heating source (4).

  Further, since the pressing spring (6a) urges both ends in the longitudinal direction of the reinforcing member (5b) outside the heating belt (2), the pressing spring (6a) itself does not contact the heating belt (2). The fluctuation range of the spring can be increased. Therefore, the reinforcing member (5b) is sufficiently moved upward to sufficiently lift the heating belt (2), and is connected to the reinforcing member (5b) along the inner periphery of the heating belt (2). The holding member (5a) can completely separate the heating belt (2) from the pressure roller (3).

Next, the toner fixing operation in the fixing device (1) configured as described above will be described separately with reference to FIGS. 1 and 2 during normal operation and when an abnormality occurs.
(Normal operation)
First, the transfer paper (22) to which the toner (23) sent from the photosensitive member (not shown) is attached is introduced from the insertion guide (24) (step 1).

  At this time, on the heating belt (2) side, as shown in FIG. 2, the pressure cam (6b) is in a pressed state, and the pressing spring (6a) is pressed down. The pressed spring (6a) pushed down biases the reinforcing member (5b) downward, that is, toward the holding member (5a). The release spring (6c) always urges the reinforcing member (5b) upward, that is, in the direction opposite to the holding member (5a), but is weaker than the urging force of the pressing spring (6a). Then, the urging force of the release spring (6c) is not working. The holding member (5a) connected to the reinforcing member (5b) presses the heating belt (2) against the pressure roller (3) to form a nip portion (7) having an appropriate nip width. .

Next, on the transfer paper (22) introduced from the insertion guide (24) to the nip portion (7), the toner (23) is heated and melted by the heating belt (2), and the pressure roller (3). Is fixed to the transfer paper (22) by the pressure (step 2).
The transfer paper (22) on which the toner (23) is fixed exits the fixing device (1) from the opposite side of the introduction guide (24) and is discharged (step 3).

(When an error occurs)
For example, when the transfer paper (22) jams in an accordion state between the heating belt (2), the pressure roller (3), and the insertion guide in the step 2 and a paper jam occurs, the abnormality detection sensor (8 ) Detects this abnormality and transmits detection information to the control unit (10) (step 11).
The controller (10) acquires the detection information, stops the rotation of the heating belt (2) and the pressure roller (3), turns off the heating source (4), and presses the pressure cam (6b). The pressure motor (9) is rotated so as to switch from the state to the non-pressed state (step 12).

With the rotation of the pressure motor (9), the pressure cam (6b) is switched to the non-pressed state as shown in FIG. 3, and the urging force of the pressure spring (6a) is released (step 13).
The reinforcing member (5b) is not urged downward, that is, to the holding member (5a) side by releasing the urging force of the pressing spring (6a). Instead, the urging force of the releasing spring (6c) is changed upwardly, that is, It is biased in the opposite direction to the holding member (5a) and moves upward together with the holding member (5a). At this time, the upper end of the reinforcing member (5b) lifts the heating belt (2) to completely separate the heating belt (2) and the pressure roller (3) (step 14).

In this way, the pressing means (6) switches between the pressing state and the non-pressing state, and when the pressing means (6) is in the non-pressing state, the holding means (5) starts from the heating belt (2) portion on the side in pressure contact with the pressure roller (3). The heating belt (2) on the opposite side is lifted away, and the heating belt (2) and the pressure roller (3) are completely separated from each other. The abnormal state can be corrected by releasing the pressure contact state with the roller (3), and when the heating belt (2) is cooled at the time of separation, there is no portion in contact with the pressure roller (3). 2) can be uniformly contracted to prevent deformation.
In particular, even when the heating source is a heat source that generates radiant heat, the contraction rate of the heating belt (2) between the portion where the heating belt (2) is in contact with the pressure roller (3) and the portion where it is not in contact is high. You can avoid things that are very different.

The holding means (5) includes a holding member (5a) along the heating belt corresponding to the nip width, and a reinforcing member (5b) in contact with the holding member (5a) at a substantially right angle, and the pressing means (6 ) Includes a pressing spring (6a) that urges the reinforcing member (5b) toward the holding member (5a), a pressure cam (6b) that switches between urging and releasing the pressing spring (6a), and a reinforcing member. Since (5b) is constituted by a release member (6c) such as a spring that urges the holding member (5a) in the opposite direction, it is possible to switch between a pressed state and a non-pressed state with a simple configuration such as a spring or a cam. it can.
Further, since the abnormality detection sensor (8) and the control unit (10) for receiving the abnormality detection information and controlling the pressure cam (6b) are provided, the pressure cam (6b) is not pressed immediately when an abnormality occurs. It is possible to switch to a state, and it is possible to quickly respond to an abnormality.

FIG. 4 is a front view showing another example of the reinforcing member, and corresponds to the reinforcing member in front view in FIG. 1. The reinforcing member (5b) shown in FIG. 1 is a plate having a rectangular shape when viewed from the front, but in the example of FIG. 3, a plate that contacts the heating belt (2) opposite to the pressure roller (3). A convex portion (26) is provided on a part in the longitudinal direction (for example, the central part), that is, on a part in the rotational axis direction of the heating belt (2) in the thickness portion of the shaped body.
In the fixing device (1) of the present embodiment, the reinforcing member (25b) as shown in FIG. 3 can be used similarly to the reinforcing member (5b) shown in FIG. However, when the reinforcing member (25b) is used, the difference is that in step 14, the convex portion (26) of the reinforcing member (25b) is lifted in contact with the heating belt (2).

  Since the reinforcing member (25b) is heated by the heating source (4) to some extent, the entire upper end corresponding to the thickness of the reinforcing member (25b) thus heated becomes the heating belt (2). When in contact, even if the contact thickness is small, there is a slight difference in belt contraction rate from the non-contact portion. Therefore, if only the convex portion (26) is brought into contact with the heating belt (2), a portion where a difference in belt contraction rate occurs can be suppressed as much as possible. Therefore, the deformation of the heating belt (2) due to the difference in belt contraction rate can be prevented more reliably.

  In the present embodiment, the abnormality detection sensor (8) is provided, and the control unit (9) that has acquired the detection information by the abnormality detection sensor (8) is configured to switch the pressure cam (6b) to a non-pressed state. This is not a limitation. For example, the pressure motor (9) does not press the pressure cam (6b) when an abnormality such as a paper jam occurs and the fixing device (1) stops due to an abnormality not linked to the abnormality detection sensor (8). It is also possible to provide a button for stopping the image forming apparatus and switching the pressure cam (6b) to the non-pressed state when the user discovers image rubbing or the like.

  The present invention is suitably used in a fixing device that employs a heating belt and uses a heating source that generates radiant heat.

FIG. 3 is a front view illustrating a configuration example of an embodiment of a fixing device according to the present invention. FIG. 2 is a left side view in a pressed state schematically showing a configuration of a main part of the fixing device in FIG. 1. FIG. 2 is a left side view in a non-pressed state schematically showing a configuration of a main part of the fixing device in FIG. 1. It is a front view which shows another example of a reinforcement member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing device 2 Heating belt 3 Pressure roller 4 Heating source 5 Holding means 5a Holding member 5b Reinforcing member 6 Pressing means 6a Pressing member 6b Pressing cam 6c Release member 8 Abnormality detection sensor 9 Control unit 10 Pressing motor

Claims (5)

In the fixing device in which the heating belt and the elastic rotating body are pressed against each other and conveyed with the transfer paper interposed therebetween, and the toner on the transfer paper is fixed.
The heating belt includes a heating source for heating the heating belt, holding means for pressing the heating belt and the elastic rotating body with an appropriate nip width, and the heating belt via the holding means. A pressing means for pressing the rotating body,
It said holding means includes a side along the heating belt with along the heating belt in correspondence with the nip width and the opposite holding member flat portion at the nip center portion of the surface is formed of the planar portion of the holding member It consists of a plate-shaped reinforcing member that is in contact with the substantially right angle,
When an abnormality occurs, the pressing means switches from a pressing state to a non-pressing state, the holding member of the holding means moves away from the heating belt portion on the side in pressure contact with the elastic rotating body, and the reinforcing member contacts the holding member. The fixing device is characterized in that the heating belt portion on the opposite side is pushed at the end opposite to the side so that the heating belt and the elastic rotating member are not in contact with each other.   The fixing device according to claim 1, wherein the heat source is a heat source that generates radiant heat. The pressing means includes a pressing member that urges the reinforcing member toward the holding member, a pressure cam that switches urging and releasing the pressing member, and urges the reinforcing member in a direction opposite to the holding member. And a release member that
When in the pressed state, the pressing member biases the reinforcing member toward the elastic rotating body, and when in the non-pressed state, the biasing of the pressing member is released by the pressure cam, and only the release member The fixing device according to claim 1, wherein the fixing device is biased. An anomaly detection sensor for detecting an anomaly occurrence;
The fixing device according to claim 1, further comprising: a control unit that receives detection information of the abnormality detection sensor and controls the pressure cam.   5. The fixing device according to claim 1, wherein the reinforcing member is a portion in contact with the heating belt, and a convex portion is provided in a part of the heating belt in a rotation axis direction.

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