JPH06118834A - Form peeling off device for fixing device - Google Patents

Abstract

PURPOSE:To satisfactorily perform action for peeling off a form by preventing the angle and the position of the guiding surface of a pawl for the form from being changed even in a state where a pawl tip is abraded as for a peeling off pawl member arranged in the form ejection part of a heat roll system fixing device. CONSTITUTION:In the fixing device where a fixing roll 11 and a pressure roll are arranged to be opposed, the peeling off pawl member 20 arranged at a form peeling off position for the roll 11 is provided in a supporting bracket 25 using means capable of moving in parallel with a base part. Even in the state where the pawl tip 23 is abraded, a long hole 21 provided on the pawl is energized by a spring 28 along supporting pin members 26 and 27, so that a position where the pawl tip part 23 abuts on the roll 11 is kept constant and the angle theta of the guiding surface for the form the being the lower surface of the pawl is kept constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet peeling device in a heat roll type fixing device, and more particularly to a position where the tip of the claw comes into contact with the roll member and the angle of peeling of the sheet even when the peeling claw member is worn. The present invention relates to a sheet peeling device of a fixing device that can maintain a constant value.

[0002]

2. Description of the Related Art In an image forming apparatus, such as an electronic copying machine or a laser printer, which forms a toner image on an image bearing member by using an electrophotographic method, the toner image formed on the image bearing member is transferred onto a sheet. , A means for making a copy by fixing the paper carrying the toner image through a fixing device. As the fixing device, a heat roll type fixing device is generally used in many cases, and in the fixing device, a pressure roll is capable of exerting a predetermined nip pressure against a fixing roll having a built-in heat source. When pressing and passing the paper between both rolls, heat and pressure are applied so that the fixing action can be performed. In addition, in the fixing device, in order to prevent peeling failure in a state in which the sheet is attached to the roll member due to the action of the sheet being attached to the fixing roll by the melted toner or being curved. In addition, a peeling claw member is arranged in the paper discharge portion of the fixing device.

As the fixing device, for example, Japanese Unexamined Patent Publication No.
An apparatus as disclosed in Japanese Patent Publication No.-267986 is known. In the fixing device shown in the above-mentioned conventional example, a peeling claw member arranged with respect to the fixing roll is provided so as to be swingable via a support shaft, and a means for pressing the claw tip portion against the roll surface with a predetermined pressure by a spring. Is used. In addition, a general image forming apparatus has a mechanism as shown in FIG. In the image forming apparatus 1 shown in FIG. 4, the electrophotographic toner image forming mechanism is arranged on the photosensitive drum 2 as an image carrier, and the toner image formed on the photosensitive drum 2 is Transfer / Peeling A method of transferring to the paper P by the discharge of the corotron 3 is used.

Further, between the photosensitive drum and the fixing device 10 formed as a fixing device of a heat roll system,
Paper transport device 4 by suction transport means and entrance guide 5
And the sheet P carrying the toner image on the fixing device 1.
It is conveyed toward 0. The fixing device 10
Then, the fixing roll 11 and the pressure roll 12 are arranged, and the peeling claw member 15 as a paper peeling device is arranged at the downstream portion of the nip portion of both rolls. The peeling claw member 15
In the same manner as the one disclosed in the publication of the conventional example, while being provided so as to be swingable via the support shaft 16, the claw tip portion 17 is lightly pressed against the roll 11 by the spring 19 to perform the action of peeling the paper. I am trying. Then, the sheet peeled by the sheet peeling device is discharged toward the discharge tray or the like along the guide plate 6 of the discharge path.

[0005]

As shown in FIG. 4, when the paper peeling device is constructed in a state where the tip 17 of the peeling claw member 15 is pressed against the fixing roll 11, the claw is used. As shown in FIG. 5, when the tip portion is not worn at all, the claw tip portion 17 of the peeling claw member is moved to the roll 1
The distance H between the height in contact with 1 and the axial center of the roll and the peeling angle θ1 of the paper by the tip of the claw satisfy the condition that the peeling action on the paper can be favorably performed.
However, since the peeling claw member 15 is often made of a relatively soft plastic, it is easily worn by sliding on the roll. Then, while using the peeling claw member, as shown in FIG.
As shown in FIG.
There is a problem that the position of the claw tip 17 in contact with the roll gradually changes.

In the state shown in FIG. 6, since the peeling claw member 15 is swung counterclockwise via the support shaft 16, the setting angle is gradually reduced to θ2. The height H at which the tip of the claw comes into contact with the roll is reduced to H1. A small value of the setting angle θ2 leads to a problem that the paper attached to the roll is less likely to be peeled off, and the leading end of the paper hits against the leading end of the claw and is stopped. Therefore, even if the paper is peeled from the roll, there is a problem that it abuts against the guide surface under the peeling claw member and is stopped, and a jam occurs.

Therefore, in order to solve the above-mentioned problem of defective peeling of paper, for example, Japanese Patent Laid-Open No. 2-87179.
As shown in Japanese Patent Laid-Open Publication No. 2003-242242, it has been proposed to improve the means for supporting the peeling claw member and biasing it with a spring. In the above-mentioned conventional example, the position of the support shaft for supporting the peeling claw member is arranged on the extension of the contact angle between the roll tip and the roll for peeling the sheet, and is arranged with respect to the peeling claw member. The length of the working arm by the spring is set to be at least twice the distance between the support shaft and the tip of the peeling claw, and the direction of action by the spring is arranged parallel to the working angle of the claw tip.

However, even when the supporting condition for the peeling claw member is set as in the conventional example, when the tip of the claw is greatly worn, the peeling angle of the peeling claw member with respect to the sheet gradually changes. However, the problem of peeling failure remains. Therefore, as in the conventional example,
When the conditions for supporting the peeling claw member are set, it may be considered that the peeling claw member is made of a material that does not easily wear. However, when the peeling claw member is made of a hard material, the coating on the surface of the roll may be worn, and scratching the surface of the roll causes a problem of impairing the fixing property.

[0009]

SUMMARY OF THE INVENTION The present invention eliminates the above-described relationship between wear of the peeling claw member and defective peeling of the paper. When the peeling claw member is made of a relatively soft material, the tip of the claw is An object of the present invention is to provide a sheet peeling device of a fixing device that can perform a peeling action of a sheet in a good condition even when it is worn.

[0010]

SUMMARY OF THE INVENTION The present invention comprises an image carrier for forming a toner image using an electrophotographic system, and a heat roll type fixing device disposed downstream of the image carrier. The present invention relates to a device for fixing a sheet, on which a toner image is transferred from the image carrier, through a fixing device to apply heat and pressure. In the present invention, a peeling claw member is arranged in the sheet discharge portion of the fixing device, and a long hole that defines the moving direction of the claw member is arranged in the peeling claw member, and is supported to support the peeling claw member. Even if the bracket is arranged, the pin member provided on the support bracket is engaged with the long hole provided on the peeling claw member, and the tip of the peeling claw member is worn,
The position where the tip of the claw contacts the fixing roll and the peeling angle of the sheet by the claw are set to constant conditions.

Further, in the fixing device of the present invention, a spring is arranged to urge the peeling claw member toward the fixing roll, and the direction of action of the spring is the direction of the long hole provided in the peeling claw member. Can be set in parallel. Further, in the present invention, the peeling claw member is supported via a long support arm, is swingably received via a fulcrum at an intermediate portion of the support arm, and a spring is arranged above the support arm, The peeling claw member is swingably supported at the lower end, and even when the tip of the peeling claw member is worn,
It is also possible to use a mechanism in which the position where the tip of the claw comes into contact with the fixing roll and the peeling angle of the sheet by the claw are set to constant conditions.

As described above, by providing a means for supporting the peeling claw member with respect to the roll of the fixing device, the peeling claw member is made of soft plastic, and the tip of the claw of the peeling claw member is worn. Even in such a case, the peeling action on the sheet can be always performed under the same conditions. Also,
Since the peeling claw member of the present invention does not change the peeling condition with respect to the paper, peeling failure does not occur unlike the case of the conventional peeling claw member, and the occurrence of a jam in the fixing device is prevented. Can be reduced. Further, even when the supporting arm for the peeling claw member is configured to be very long, the condition in which the tip of the claw contacts the roll can be maintained substantially constant, and thus peeling failure can be prevented. And when using those means,
By forming the peeling claw member from soft plastic or the like, it is possible to prevent the coating of the roll member from being damaged and prevent the copy from being improperly fixed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet peeling device of a fixing device according to the present invention will be described with reference to the illustrated example. The example shown in FIG. 1 is similar to the case of the image forming apparatus shown in FIG. 4 above. When fixing a sheet on which a toner image is transferred from a photosensitive drum through a fixing device, the sheet is fed from the fixing roll. The case where the peeling claw member 20 is arranged in order to peel off is shown. In the example shown in FIG. 1, the peeling claw member 20
Is a support bracket 2 supported by the frame of the fixing device.
5 is supported so as to be movable in the direction of line A,
The tip portion 22 of the claw is pressed against the fixing roll 11 so that the sheet is peeled off. The peeling claw member 20
Has a long hole 21 in its main body, and a support pin member 26 provided in a support bracket 25 with respect to the long hole 21.
27 is inserted. The direction A of the long hole 21
Is set parallel to the acting direction B of the spring 28 for urging the peeling claw member 20.

The claw tip portion 22 of the peeling claw member 20 is in contact with the fixing roll 11 of the fixing device at a point Q, and the position of the point Q is the height from the axis R of the roll 11. The interval H is set. Also, the axis R of the roll 11
The angle θ formed by the line connecting the point and the point Q and the paper peeling surface X of the peeling claw member is such that the paper to be peeled from the roll is the peeling surface X
Is set to an angle that allows for accurate sliding along the. Therefore, in the state shown in FIG. 1, the peeling claw member 20 peels the paper from the roll 11 and exerts the action of guiding the paper toward the discharge portion along the lower surface of the peeling claw member 20. You can

The peeling claw member of the present invention constructed as described above can be constructed by using a comparatively soft plastic material such as polyimide resin, and when it is pressed by a roll, the claw is formed. The tip portion 22 can be configured to slide on the covering member of the roll and gradually wear. Then, as the nail tip 22 is worn during use of the peeling claw member 20, as shown in FIG.
The wear portion 23 of the claw gradually disappears, and the position of the tip of the claw in contact with the roll gradually changes toward the inside of the main body of the peeling claw member.

However, in the peeling claw member 20 of the present invention, when the tip of the claw is worn, the peeling claw member is guided by the support pin member along the inclination angle of the long hole 21, and the peeling claw is removed. The member 20 is pressed by the spring 28. Since the claw tip of the peeling claw member is pushed toward the roll 11 by the pressing action of the spring, the contact point Q of the claw tip with the roll on the paper guide surface does not change at all.

Further, since the sliding angle of the peeling claw member 20 is set by the elongated hole and the support pin member, with respect to the line formed by the point Q where the tip of the claw contacts and the axis R of the roll. , The angle formed by the line X on the peeling surface of the paper by the peeling claw member,
That is, the setting angle θ does not change at all. Therefore, in the peeling claw member of the present invention, the action of peeling the sheet from the roll 11 is always maintained constant even when the tip of the claw gradually wears.

In the example shown in FIG. 1, the peeling claw member 2 is used.
Although the case where the long hole and the support pin member are used to move 0 has been described, in the present invention, as shown in FIG. 3, the peeling claw member 30 is supported via the very long support arm 32. A mechanism for doing so can be used. By setting the distance between the position supporting the peeling claw member 30 and the fulcrum 33 to be long, even if the tip of the claw is worn, the position where the tip of the peeling claw member is pressed by the roll is not significantly changed. Can be In the example shown in FIG. 3, a fulcrum 33 is formed at a predetermined position of the support arm 32, and a spring 34 is arranged above the fulcrum to swing the support arm 32 counterclockwise through the fulcrum 33. The mechanism of the system is configured. In addition, the support arm 3
A peeling claw member 30 is arranged at the other end of the sheet 2 via a support shaft 31, and the tip of the claw of the peeling claw member 30 is pressed against a roll so that the sheet is peeled.

In the fixing device 10 shown in FIG. 3, with respect to each of the fixing roll 11 and the pressure roll 12,
Although a peeling claw member can be arranged, in this embodiment,
An example in which a peeling claw is arranged with respect to the fixing roll 11 is shown. Further, as the peeling claw member 30, a member made of a relatively soft plastic, such as the claw member of FIG. 1, is used, and the claw member is relatively easily worn by being pressed by the roll. Configured as. In addition,
In the embodiment of FIG. 3, the spring 34 for urging the support arm 32 in the swinging direction is constructed as a member capable of exerting a force of lightly pressing the peeling claw member 30 against the roll. The strength of the spring is set to have an arbitrary strength depending on the radius of action of the arm of the support arm.

In the peeling claw member 30 shown in FIG. 3, the
Even if the tip of the claw gradually wears due to friction with the roll 11, since the radius of action of the support arm that supports the peeling claw member is very large, the position of the claw tip of the peeling claw member in contact with the roll. Hardly changes. Further, the angle θ formed by the axis of the roll and the contact point of the peeling claw member with respect to the sheet guiding surface of the peeling claw member is not strictly set as in FIG. 1, but is maintained at a substantially constant value. Can be made.

Therefore, as shown in FIG. 3, by holding the peeling claw member by the support arm having a large turning radius, even if the tip of the claw of the peeling claw member is worn, the peeling action on the paper is kept constant. It becomes possible to configure a mechanism that can be performed under conditions. That is, FIG.
When the peeling claw member 30 is supported by the support arm 32 having a large action radius as shown in FIG. 3, the angle of the lower surface of the claw of the peeling claw member with respect to the photosensitive drum may change greatly. Even if the tip of the claw is worn, the angle of the guide surface with respect to the sheet is maintained substantially constant. Then, since the paper is guided to the discharge side along the guide surface of the claw, there is an inconvenient problem that the paper hits the guide surface below the claw and stops like the conventional peeling claw member. It can be prevented from occurring.

The peeling claw member provided with the supporting means as described above can be installed in a heat roll type fixing device having an arbitrary mechanism. It can also be attached to a roll. Further, as shown in FIG. 1, as the guide means for preventing the position of the tip of the paper peeling portion of the claw member from changing, an arbitrary guide mechanism other than the illustrated one can be provided. Is.

[0023]

Since the sheet peeling device of the fixing device of the present invention has the above-mentioned structure, the supporting mechanism for the peeling claw member is complicated only by slightly changing the supporting mechanism for the peeling claw member. It is possible to easily provide the peeling means for the paper without doing so. Further, by providing a means for supporting the peeling claw member with respect to the roll of the fixing device,
The peeling claw member is made of soft plastic, and even when the tip of the claw of the peeling claw member is worn, the peeling action on the sheet can be always performed under the same condition. Further, in the peeling claw member of the present invention, since the peeling condition for the paper does not change, peeling failure does not occur unlike the case of the conventional peeling claw member, and a jam in the fixing device is prevented. Occurrence can be reduced.

Further, in the present invention, even when the supporting arm for the peeling claw member is constructed to be very long, the condition in which the tip of the claw comes into contact with the roll can be maintained substantially constant, so that peeling failure can be prevented. Can be prevented. Therefore, when these means are used, by forming the peeling claw member from soft plastic or the like, it is possible to prevent the coating of the roll member from being damaged and prevent the copy from being improperly fixed. .

[Brief description of drawings]

FIG. 1 is a side view showing a structure and a support mechanism of a peeling claw member of the present invention.

FIG. 2 is an explanatory view of a state where the peeling claw member is worn.

FIG. 3 is an explanatory view of another embodiment of the support mechanism for the peeling claw member of the present invention.

FIG. 4 is an explanatory diagram showing a configuration of a general electronic copying machine and a peeling claw member.

FIG. 5 is an explanatory diagram of a relationship between a conventional peeling claw member and a fixing roll.

6 is an explanatory view of a state where the peeling claw member of FIG. 5 is worn.

[Explanation of symbols]

1 electronic copying machine, 10 fixing device, 11 fixing roll, 12 pressure roll, 15/20/30
Peeling claw member, 21 long hole, 22 claw tip,
25 support brackets, 26/27 support pin members, 28 springs, 32 support arms.

Claims (3)

[Claims] 1. An image carrier for forming a toner image by using an electrophotographic system, and a heat roll type fixing device arranged downstream of the image carrier are provided, and a toner image is formed from the image carrier. In a device for fixing a transfer sheet by applying heat and pressure to a fixing device, a peeling claw member is arranged in a sheet discharging portion of the fixing device, and a moving direction of the claw member is defined in the peeling claw member. And a support bracket for supporting the peeling claw member, and the pin member provided on the supporting bracket is engaged with the long hole provided on the peeling claw member, and the tip portion of the peeling claw member is arranged. A sheet peeling device for a fixing device, wherein the position where the tip of the claw comes into contact with the fixing roll and the angle of the guide of the sheet by the lower guide surface of the claw are set to constant conditions even when the claw is worn. 2. A peeling claw member is provided with a spring for urging it toward a fixing roll, and a direction of action of the spring is set parallel to a direction of an elongated hole provided in the peeling claw member. The sheet peeling device of the fixing device according to claim 1. 3. A peeling claw member is supported via a long support arm, is swingably received at a midpoint of the support arm via a fulcrum, and a spring is arranged on the upper part of the support arm and a lower end portion thereof is provided. Even if the peeling claw member is swingably supported, and the tip of the peeling claw member is worn, the position where the claw tip contacts the fixing roll and the peeling angle of the paper by the claw should be set to a substantially constant condition. Paper peeling device of the characteristic fixing device.