JP3620251B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and in particular, in an electrophotographic image forming apparatus or the like, the copied image is prevented from being disturbed, paper wrinkles, etc., and the recording material is guided to a heating roll (fixing roll) and a pressure roll. The present invention relates to a fixing device having a recording material guiding means.
[0002]
[Prior art]
Conventionally, as shown in FIG. 7, an electrophotographic image forming apparatus includes a photoreceptor 1, a BCR 2, an optical system 3, a developing device 4, a recording material storage container 5, a feed roll 6, a recording material transport roll 7, and a BTR 8. A heating roll 9, a pressure roll 10, a heating roll side guide member 11, a pressure roll side guide member 12, a recording material receiving tray 13, a roll 14, a retransmission path 15, and the like. Then, the recording material p is taken out from the recording material storage container 4 by the feed roll 6, and the recording material transport roll 7, the photosensitive member 1 and the BTR 8, the heating roll side guide member 11, the pressure roll side guide member 12, and the heating roll 9. And the pressure roll 10, the retransmission storage roll 14, and the like are conveyed and stored in the recording material receiving tray 13. When performing duplex copying, the retransmission path 15 is also used.
[0003]
In the conventional image forming apparatus, the following problems may occur.
(1) Since a roll type fixing device composed of a heated fixing roll and a pressure roll having elasticity is used, it is necessary to form a taper on the roll to prevent wrinkling of the water-containing paper. The recording material p is likely to warp or bounce, and image distortion is likely to occur.
(2) Since the space between the transfer and fixing in the fixing device is a short paper path and a small space, depending on various types of paper, and curling formed by copying these water-containing papers and screen copying, the behavior of the recording material p, etc. Further, the recording material guide member, in particular, the hatched portion 113 shown in FIG.
(3) Since the process speed in the fixing device is high, the behavior of the recording material p becomes unstable due to the increase in speed, and the leading edge of the recording material p is liable to collide with the surface of the heating roll or pressure roll. (Especially when copying both screens) and corner breaks.
(4) If the transfer in the fixing device is a transfer by BTR, since the fixing portion and the transfer portion are rolls, the recording material p forms a loop during running due to an unbalance of axial force, etc. Contact with the recording material guide member is caused and image distortion is likely to occur.
(5) Since the recording material p enters the fixing device substantially perpendicularly, the behavior of the recording material p becomes unstable, and is likely to cause paper wrinkles and corner breakage, causing contact with the recording material guide member. Prone to image distortion.
[0004]
Various proposals have been made to solve these problems.
A. The height or end position of the end of the recording material guide member relative to both roll pressure contact portions can be translated or oscillated, and the recording material is smoothly fed to the nip portion (Japanese Patent Laid-Open Nos. 1-273082 and 3). No. 51870, Japanese Utility Model Laid-Open No. 2-119274, Japanese Utility Model Laid-Open No. 3-4279).
This requires a solenoid, a motor, and a transmission device, and has the disadvantages of increasing the size and cost of the device. Also, if the position is changed manually, wrinkles due to erroneous operations and image quality defects are likely to occur. Furthermore, there is a problem that the operation becomes frequent.
[0005]
B. The output of the separation charge remover for double-sided copying is controlled and the sheet is adsorbed to the guide (see Japanese Patent Laid-Open No. 4-307578).
This is because the first surface is rubbed against the guide member, and rubbing lines and gloss changes are likely to occur. Further, insufficient separation occurs due to the state of the paper (paper quality and water content), and problems such as paper jams occur.
[0006]
C. A protruding guide portion having a guide surface located above the nip portion is provided to prevent contact with the pressure roll and to prevent wrinkles (see JP-A-6-130842).
This is because the two-sided copy of the water-containing paper has a strong contact with the heating roll, and the leading edge image is disturbed, the toner is scattered, the corners are bent, and excessive wrinkles are generated. In addition to the conventional example, there may be a case where a star-shaped wheel is provided on the guide material. However, there is a problem that white spots occur when there are many image areas.
[0007]
[Problems to be solved by the invention]
The present invention solves these problems, and has recording material guiding means for preventing the disorder of a copied image, paper wrinkles, etc., and guiding the recording material to a heating roll (fixing roll) and a pressure roll. An image forming apparatus is provided.
[0008]
[Means for Solving the Problems]
The present invention provides an image forming apparatus comprising a heating roll and a heating roll side guide member having a guide surface for guiding a recording material, wherein the heating roll side guide member has a main body portion and a downstream portion, At the time of double-sided image formation , the downstream portion protrudes from the center portion to the recording material entry downstream side before the leading edge of the recording material enters the nip portion. The image forming apparatus is movable so that the portion does not protrude downstream from the central portion of the recording material. Further , the heating roll side guide member may have a side on the upstream side of the recording material that projects from the both ends to the upstream side of the recording material.
[0009]
Further, a heating roll, in an image forming apparatus having a heating roller side guide member having a guide surface for guiding the recording material, and the heating roll side guide member, both end portions away from the image plane with respect to the guide surface may have a side of the recording material enters the upstream side which is formed in the direction.
[0010]
Then, the sides of the recording material enters the upstream side, cross-section in the vicinity of both end portions may be curved in a predetermined curvature.
[0011]
Furthermore , in the image forming apparatus comprising a heating roll and a heating roll side guide member having a guide surface for guiding the recording material, both ends of the heating roll side guide member are located downstream of the central portion from the central portion. the recording material enters the downstream side of the side projecting may have a.
[0012]
Further, in the image forming apparatus, the heating roller side guide member may have a side of the recording material enters downstream end portions projecting to the recording material enters the downstream side of the central portion.
[0013]
Then, the heating roll side guide member has a body portion and a downstream portion, the downstream portion, when the recording material enters, the recording material enters downstream end portions projecting to the recording material enters the downstream side of the central portion the sides may have a.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the invention will be described. Embodiments of an image forming apparatus will be described with reference to the drawings. FIG. 1 is an explanatory diagram of an example of a heating roll side guide member used in the image forming apparatus according to the first embodiment. FIG. 2 is an explanatory diagram of an example of a heating roll side guide member used in the image forming apparatus according to the second embodiment. FIG. 3 is an explanatory diagram of an example of a heating roll side guide member used in the image forming apparatus according to the third embodiment. FIG. 4 is an explanatory diagram of a first modification of the heating roll side guide member used in the image forming apparatus according to the third embodiment. FIG. 5 is an explanatory diagram of an example of a moving mechanism of a modified example of the heating roll side guide member of the image forming apparatus according to the third embodiment. FIG. 6 is an explanatory diagram of another example of a moving mechanism of a modification example of the heating roll side guide member of the image forming apparatus according to the third embodiment. FIG. 7 is an explanatory diagram of the image forming apparatus.
[0015]
An image forming apparatus according to a first exemplary embodiment will be described. As shown in FIG. 7, the image forming apparatus of this embodiment includes a photosensitive member 1, a fixing roll 2, an optical system 3, a developing device 4, a recording material storage container 5, a feed roll 6, a recording material conveyance roll 7, a BTR 8, A heating roll 9, a pressure roll 10, a heating roll side guide member 11, a pressure roll side guide member 12, a recording material receiving tray 13, a roll 14, a retransmission path 15 and the like are provided. The heating roll side guide member 11 in this embodiment is different from the conventional one, and as shown in FIG. 1, the central portion 111 is formed so as to protrude from the both end portions 112 to the recording material entering upstream side. The recording material is formed so as to have a side on the upstream side of the recording material. FIG. 1A is an explanatory diagram of the heating roll 9, the pressure roll 10, the heating roll side guide member 11, the pressure roll side guide member 12, and the recording material p in the present embodiment. 1 (c) is an arrow D ₁ explanatory view of a heating roll side guide member 11 of the present embodiment and the conventional example. A hatched portion 113 in FIG. 1C is a portion that is missing as compared with the conventional heating roll side guide member 11. In the recording material guide member having a lateral direction of 300 mm, the length (l ₂ ) in the central portion 111 is 18 mm and the length (l ₁ ) of the end portion 112 is about 13 to 5 mm. To do.
The image forming apparatus according to the present exemplary embodiment will be described using double-sided copy processing. First, as a surface copy, an optical image created by the optical system 3 is irradiated onto the photoreceptor 1, developed by the developing device 4, and transferred to the transported recording material p. The recording material p passes between the heating roll side guide member 11 and the pressure roll side guide member 12, is inserted and fixed between the heating roll 9 and the pressure roll 10, and is supplied to the recording material receiving tray 13. Is done. Next, the recording material p partially stored in the recording material receiving tray 13 so as not to be discharged from the temporary roll 14 for backside copying passes through the re-transmission path 15 again, and again, the optical system 3 and the photosensitive member. The optical image is transferred to the back surface of the recording material p by 1 or the like. The recording material p passes again between the heating roll side guide member 11 and the pressure roll side guide member 12, and is inserted and fixed between the heating roll 9 and the pressure roll 10 to complete the double-sided copying process. Then, it is discharged out of the image forming apparatus. The heating roll side guide member 11 used in the image forming apparatus of this embodiment is formed so that the central portion has a side on the upstream side of the recording material that protrudes upstream of the recording material from both ends. As a result, even when a jump that is likely to occur at one or both of the rear end portions of the recording material p occurs when being supplied from the photosensitive member to the heating roll and the pressure roll, the heating roll-side guide member 11 is in the center. Since the portion 111 forms a side on the upstream side of the recording material that protrudes from the both ends 112 to the upstream side of the recording material, the central portion 111 of this side guides the central portion of the leading end of the recording material, and the recording material p Since there is no portion of the heating roll side guide member 11 corresponding to both end portions of the rear end, even if the recording material p jumps up, it does not come into contact with the heating roll side guide member 11, and stains and images are not printed. Disturbance does not occur.
The shape of the portion connecting the central portion 111 and the end portion 112 on the upstream side of the recording material entry is a curve such as a straight line or an arc so that it can be guided without difficulty even if the recording material p collides. Preferably, it may be left-right symmetric or not symmetric.
[0016]
Next, an image forming apparatus of Example 2 will be described. The image forming apparatus of the present embodiment is the same as that of the first embodiment, but the heating roll side guide member 11 is different. As shown in FIG. 2, the heating roll side guide member 11 in the present embodiment is formed in a direction in which both end portions 112 are away from the image surface with respect to the guide surface, for example, a curved surface having a constant cross section. It has a recording material ingress upstream side. 2A is an explanatory diagram of the heating roll 9, the pressure roll 10, the heating roll side guide member 11, the pressure roll side guide member 12, and the recording material p, and FIG. 2B is the heating roll side. It is explanatory drawing of the guide member. FIG. 2C and FIG. 2D are cross-sectional explanatory views at the central portion E and the end portion F in FIG. The amount of separation from the image surface in FIG. 2B is set to 1.5 mm or more at the maximum in the heating roll side guide member having a horizontal direction of 300 mm and a vertical length (l ₂ ) of 18 mm. As a result, both end portions of the leading end of the recording material p are less likely to collide with the heating roll guide member 11, and the heating roll guide member 11 is deformed so that the collision portion becomes a curved surface even when the collision occurs. Generation of wrinkles and the like can be prevented. In addition, as in the first embodiment, both sides of the rear end of the recording material p are free from stains and image disturbance due to curling. Note that the curvature may be left-right symmetric or not symmetric.
[0017]
An image forming apparatus according to a third exemplary embodiment will be described. The image forming apparatus of this embodiment is the same as that of Embodiments 1 and 2, but the heating roll side guide member 11 is different. As shown in FIG. 3, the heating roll side guide member 11 in the present embodiment has a recording material entry downstream side formed such that both end portions 115 protrude from the center portion 114 to the recording material entry downstream side. doing. 3A is an explanatory diagram of the heating roll 9, the pressure roll 10, the heating roll side guide member 11, the pressure roll side guide member 12, and the recording material p. FIG. 3B is a side view of the heating roll. it is an arrow _{D 3} illustration of the guide member 11. The protrusion amount (l ₃ ) is 1 to ₃ mm in the heating roll side guide member having a horizontal direction of 300 mm and a vertical length (l ₂ ) of 18 mm. As a result, GAP ₂ becomes smaller than conventional GAP _1, and recording material p is generated from a slight gap (GAP ₂ ) between the heating roll and the guide material after passing the guide material, for example, which occurs during double-sided copying of water-containing paper. It is possible to prevent corner folds caused by the edges at both ends of the leading edge of the sheet falling to the heating roll and severe paper wrinkles due to the corner folds. Note that the protruding amount may be left-right symmetric or not symmetric.
[0018]
The modification of the heating roll side guide member 11 in Example 3 is demonstrated. As the heating roll side guide member 11, instead of using an integrally formed member, a member formed as a separate piece is used as shown in FIG. That is, the heating roll side guide member 11 has a main body portion 116 and a downstream portion 117, and the downstream portion 117 has both end portions 119 on the downstream side of the recording material entering from the central portion 118 when the recording material p enters. It has a protruding recording material entry downstream side. Even in this case, it is possible to prevent corner folding and paper wrinkling caused by the end of the leading end of the recording material p colliding with the heating roll side guide member 11.
[0019]
Note that the protruding portion (third guide portion) 119 has a large curl, for example, when the two-sided copy is performed using a high water content paper of a certain level or more, so that the corner break or the like cannot be prevented. Therefore, it can be prevented by increasing the amount of protrusion, but if it is too large, the protrusion 119 comes into contact with the recording material p, so that the image is rubbed. Therefore, the third guide portion 119 is configured as a separate piece, and, for example, during double-sided copying, the separate piece is moved so as to become the third guide portion 119 before the leading end of the recording material p enters the nip portion, and Then, the recording material p is moved by a certain distance from the leading edge and moved so that the third guide portion 119 does not protrude while the paper p passes through the nip portion (the present invention) . Thereby, particularly when performing double-sided copying of water-containing paper, both ends of the leading end of the recording material p can be curled and peeled to the heating roll side, and can be guided to the nip portion, so that the heating roll and the second guide surface It is possible to prevent the leading end from entering the minute gap of the recording medium, to prevent corner breakage, to prevent severe paper wrinkling, and when the rear end of the recording material p passes, the third guide portion. Since 119 can be prevented from protruding, it does not come into contact. As a result, it is possible to achieve a significant improvement (particularly, prevention of both paper wrinkles and image blurring during double-sided copying) compared to the conventional one. Since there is no need to move the entire guide member 11, a large drive device is not required. 5 and 6 show examples of mechanisms for moving the third guide part 119. FIG. FIG. 5 shows the third guide portion 119 having two pieces. FIG. 6 shows three pieces as the third guide portion 119, FIG. 6 (a) shows only one side, and FIG. 6 (b) is a cross-sectional explanatory view thereof. As the opening / closing operation, for example, a signal (ON) is sent to a mechanism (solenoid or the like) that operates the third guide portion 119 when the pulse count number of the encoder of the main motor exceeds a certain value (t1) from the paper feed clutch ON signal. give. Then, after a certain value (t2) has passed, a signal (OFF) is given to enable such an operation.
[0020]
【The invention's effect】
According to the present invention, it is possible to obtain an image forming apparatus having recording material guiding means for preventing a copied image from being disturbed, paper wrinkles and the like and guiding the recording material to a heating roll (fixing roll) and a pressure roll.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an example of a heating roll side guide member of an image forming apparatus according to a first embodiment.
FIG. 2 is an explanatory diagram of an example of a heating roll side guide member of the image forming apparatus according to the second embodiment.
FIG. 3 is an explanatory diagram illustrating an example of a heating roll side guide member of the image forming apparatus according to the third exemplary embodiment.
FIG. 4 is an explanatory diagram of a modified example of the heating roll side guide member of the image forming apparatus according to the third embodiment.
FIG. 5 is an explanatory diagram illustrating an example of a moving mechanism of a modified example of the heating roll side guide member of the image forming apparatus according to the third exemplary embodiment.
6 is an explanatory diagram of another example of a moving mechanism of a modified example of the heating roll side guide member of the image forming apparatus of Embodiment 3. FIG.
FIG. 7 is an explanatory diagram of an image forming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor, 2 BCR (charging roll), 3 Optical system, 4 Developer, 5 Recording material storage container, 6 Feed roll, 7 Recording material conveyance roll, 8 BTR (transfer roll), 9 Heating roll, 10 Pressure roll 11 Heating roll side guide member, 111 Recording material entry upstream central portion, 112 Recording material entry upstream end portion, 114 Recording material entry downstream central portion, 115 Recording material entry downstream end portion, 116 Main body portion, 117 Downstream portion, 118 downstream portion central portion, 119 downstream portion end portion, 12 pressure roll side guide member, 13 recording material receiving tray, 14 roll, 15 retransmission path, p recording material.

Claims (2)

In an image forming apparatus comprising a heating roll and a heating roll side guide member having a guide surface for guiding a recording material,
The heating roll side guide member has a main body portion and a downstream portion, and at the time of double-sided image formation, the downstream portion enters the recording material from the center portion at both ends before the leading edge of the recording material enters the nip portion. with protruding downstream while passing through the recording material is nip, images forming device you wherein a movable so both end portions do not protrude into the recording medium enters the downstream side of the central portion. 2. The image forming apparatus according to claim 1, wherein the heating roll side guide member has a side on the upstream side of the recording material that protrudes toward the upstream side of the recording material from the center of both ends.

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