JPH06127742A - Electrophotographic recording device - Google Patents

Abstract

PURPOSE:To smoothly transfer a sheet after the image copying to a fixation device without generating the trouble such as jamming and rubbing on the image. CONSTITUTION:A sheet edge detecting means 38 for detecting the top edge and rear edge of a sheet S after image copying is installed under image forming case 19. On the downstream side in the sheet transfer direction (a) of the sheet edge detecting means 38, a roller 40 having a projection 40a on the outer periphery is installed so as to be turned in the normal and reverse directions. If the top edge or rear edge of the sheet S is detected by the sheet edge detecting means 38 when the sheet S is transferred to a fixation device 23 after the image copying, the roller 40 is turned to set the sheet S at a regulation position in a prescribed timing by a control means, and the top edge or rear edge in curled state is flipped by the projection part 40a, and floating-up of the sheet S is prevented. After suppressing the floating-up of the top edge or rear edge, the restraint is released to set the roller 40 to each retreat position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, a copying machine, a facsimile, etc. using a laser, charging, optical writing,
Form an image on the sheet on the photoconductor by development, transfer, etc.,
The present invention relates to an electrophotographic recording device that puts the sheet in a fixing device to fix the transferred image.

[0002]

2. Description of the Related Art Conventionally, for example, in a laser printer, an image forming case is provided in the main body of the apparatus, and some image forming means such as a photoconductor, a transfer device and a developing device are provided in the image forming case. There is something stored. Then, among such printers, there is a printer that guides the sheet after the image transfer on the lower surface of the image forming case to the fixing device, and fixes the transferred image by the fixing device and records on the sheet. It was

[0003]

However, in such a conventional printer, when the curled sheet is transferred to the fixing device after image transfer, the sheet is formed in the gap between the entrance guide of the fixing device and the image forming case. However, the image transfer surface of the sheet comes into contact with the entrance guide to cause image rubbing, or the sheet enters the gap and jams the sheet.

Therefore, an object of the present invention is to make it possible to smoothly convey a sheet after image transfer to a fixing device without causing troubles such as jamming and image rubbing as described above. is there.

[0005]

Therefore, the present invention provides
For example, as shown in the following illustrated embodiment, in an electrophotographic recording apparatus in which the sheet S after the image transfer is placed in the fixing device 23 to fix the transferred image on the sheet S, the front and rear ends of the sheet S after the image transfer are performed. A sheet edge detecting means 38 for detecting the edge, a regulating position provided downstream of the sheet edge detecting means 38 in the sheet conveying direction and for suppressing the floating of the sheet S before entering the fixing device 23, and a retracting position for releasing the pressing. A regulating means such as a roller 40 movable to a position; and a controlling means for driving the regulating means to the regulating position at a predetermined timing when the sheet edge detecting means 38 detects the leading edge or the trailing edge of the sheet S. It is characterized by comprising.

According to the second aspect of the present invention, the sheet S after the image transfer is carried out, for example, as shown in the following illustrated embodiment.
Of the curl of the sheet S after the image transfer in an electrophotographic recording apparatus in which the sheet is guided by a sheet guide such as the conveyor belt 35 into the fixing device 23 and the fixing device 23 fixes the transferred image on the sheet S. Based on the detection result of the curl detection unit 55, and a sheet guide driving unit that changes the drop h between the sheet inlet 53 of the fixing unit 23 and the sheet guide fixing unit 23 side. And a control means for adjusting the drop h by the sheet guide driving means.

According to a third aspect of the present invention, for example, as shown in the following illustrated embodiment, in the electrophotographic recording apparatus according to the second aspect, the sheet guide is a conveyor belt 35 for conveying the sheet S, The conveying belt 35 is brought into contact with the guide rollers 60 and 61 and is stretched between the driving roller 36 and the driven roller 37, and the driven roller 37 is moved by the sheet guide driving means to move the conveying belt 35 at the position of the guide rollers 60 and 61. Is bent to change the drop h.

[0008]

According to the first aspect of the invention, when the sheet S after the image transfer is conveyed to the fixing device 23, when the sheet edge detecting means 38 detects the leading edge of the sheet S, the control means performs timing. After that, the restricting means is moved to the restricting position to suppress the floating of the sheet S before entering the fixing device 23, and then the restricting means is returned to the retracted position. Then, when the sheet edge detecting means 38 detects the trailing edge of the sheet S, the controlling means moves the regulating means to the regulating position at a timing to press the floating of the sheet S, and then retracts the regulating means. Return to position.

According to the second aspect of the invention, when the sheet S after image transfer is conveyed, the curl detection means 55 detects the curl size of the sheet S, and the control means based on the detection result of the curl detection means 55. Thus, the sheet guide driving means is driven to adjust the drop h between the sheet inlet 53 of the fixing device 23 and the fixing device 23 side of the sheet guide.

According to the third aspect of the present invention, when adjusting the drop, the driven roller 37 is moved by the sheet guide driving means based on the detection result of the curl detecting means 55, and the conveying belt 35 is moved at the position of the guide rollers 60 and 61. Bend to adjust the drop h.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows a laser printer which is an embodiment of the present invention, and shows the overall schematic structure of its internal mechanism.

Reference numeral 10 in the drawing is a main body of the apparatus, which is mounted on an optional dedicated table 11. A drum-shaped photoconductor 12 that rotates clockwise in the drawing is provided in the center of the apparatus main body 10. Around the photoreceptor 12,
The charging device 13, the optical writing device 14, the developing device 15, the transfer device 16, and the cleaning device 17 are sequentially arranged in the rotation direction. Then, together with the photoconductor 12, the developing device 15 and the transfer device 1
6. The cleaning device 17 is housed in the image forming case 19 in an exchangeable manner. The image forming case 19 is provided so as to be drawn out from the apparatus body 10.

On the other hand, on the right side of the apparatus main body 10 in the drawing,
The paper feed cassettes 20 are detachably attached to upper and lower two stages. Further, on the right side of the transfer device 16, the registration roller 21
To place. On the other hand, on the side opposite to the registration roller 21 with the transfer device 16 sandwiched between them, the transport device 22, the fixing device 23, and the switching means 24 are arranged side by side.

By the way, the dedicated table 11 is provided with a sheet reversing / conveying path 27 in communication with the double-sided print discharge path 26 provided on the lower left side of the apparatus main body 10 in the figure, and from the sheet reversing / conveying path 27 to the apparatus. A sheet re-feeding path 28 that communicates with the main body 10 is provided. Further, a large-volume sheet feeding device 29 is detachably attached to the right side of the dedicated table 11.

In this laser printer, however, the sheet feeding rollers 31, 32, and 33 are appropriately selected and driven, and the sheet S is fed to the sheet feeding cassette 20 or 20 or the large-volume sheet feeding device 29.
It is sent out from the inside one by one and hits the registration roller 21 to stop.

On the other hand, the surface of the photosensitive member 12 is sequentially charged by the charger 13 while rotating clockwise in the figure, and the next optical writer 14 irradiates the laser light so that the surface of the photosensitive member 12 is electrostatically latent. An image is formed, and subsequently, the electrostatic latent image is sequentially visualized when passing through the position of the developing device 15. Then, the registration roller 21 is driven in synchronism with the image to drive the sheet S to the photoreceptor 1.
Send it to 2. Then, the visible image on the photoconductor 12 is transferred onto the surface of the sheet S by the transfer device 16. After the transfer, the surface of the photoconductor 12 is cleaned by the cleaning device 17, while the sheet S after the image transfer is conveyed to the fixing device 23 by the conveying device 22 and the transferred image is fixed by the fixing device 23. To do. Then, the discharge stack unit 3 passes through the discharge transport path 34.
Discharge to 5.

Further, when it is desired to record on the back side of the sheet S, the discharging direction is switched by the switching means 24, and the sheet S after the image fixing is guided to the sheet reversal conveying path 27 through the double-sided print discharging path 26, and there. Reverse and re-feed path 28
It is again conveyed into the main body 10 of the apparatus, and is abutted against the registration roller 21 again and stopped. Then, similarly, the recording is performed on the back side and the sheet is discharged onto the sheet discharge stack section 35.

By the way, in the illustrated laser printer described above, the conveyor 22 is provided with a conveyor belt 35 which is a sheet guide as shown in FIG. 1, and the conveyor belt 35 is stretched between a driving roller 36 and a driven roller 37. It becomes.
Then, inside the conveying belt 35, a sheet edge detecting means 38 for detecting the leading edge and the trailing edge of the sheet S after image transfer.
To provide. As the sheet edge detection means 38, for example, a light transmission type / reflection type photosensor or the like is used.

Therefore, in the image forming case 19, a step portion 19b is formed on the lower surface 19a side of the fixing device 23, that is, downstream of the sheet edge detecting means 38 in the sheet conveying direction.
Two rollers (regulating means) 40 are provided on the step portion 19b.
As shown in FIG. 2, each roller 40 has a protrusion 40a on the outer periphery.
And each of them is provided on the shaft 41 so as to be rotatable in the forward and reverse directions.
The projection 40a is normally held in the retracted position shown in the figure. A gear 42 for transmitting the driving force of a drive motor (not shown) is attached to one end of the shaft 41.

As shown in FIG. 1, the fixing device 23 has an upper entrance guide plate 46 on the right side of the upper cover 45 in the figure.
The lower entrance guide plate 48 on the right side of the lower cover 47.
Attach. Then, the lower end side of the upper entrance guide plate 46 and the upper end side of the lower entrance guide plate 48 are respectively bent toward the fixing nip portion 52 between the fixing roller 50 and the pressure roller 51, and the sheet entrance 53 is formed in front thereof. It becomes.
Reference numeral 54 in the drawing denotes a sheet separator that separates the sheet S after the image transfer from the photoconductor 12.

In the illustrated laser printer, when the sheet S after the image transfer is conveyed to the fixing device 23, when the leading edge of the sheet S is detected by the sheet edge detecting means 38, the sheet edge detecting means 38 detects it. Based on the signal, the control means (not shown) issues an operation signal at a predetermined timing to drive the drive motor. Then, as shown in FIG. 3, the roller 40 is rotated clockwise to bring the protrusion 40a to the downward regulation position, and the protrusion 40a repels the curled front end side of the sheet S as shown by a dotted line. Push down. Then, the roller 40 presses the rising of the sheet S and guides the leading end thereof to the sheet inlet 53, and then rotates to the original retracted position and stands by. Next, when the trailing edge of the sheet S is detected by the sheet edge detecting means 38, the control means drives the drive motor in the reverse direction at a timing based on the detection signal from the sheet edge detecting means 38 to reverse the roller 40 in the figure. As shown in FIG. 4, the roller 40 is rotated clockwise, and the roller 40 is again set to the restricting position. This time, the curled rear end side of the sheet S is repelled by the protrusion 40a and pushed down as shown by the dotted line, and the rear end side is lifted. Hold down.

In the illustrated embodiment described above, the roller 40 having the protrusion 40a is rotated to prevent the curled sheet from rising. However, this invention
The floating of the sheet can be suppressed not only by the structure of rotating such a roller but also by a structure of using a plate-like member and appropriately moving it up and down, for example.

Further, in the present invention, for example, a configuration as shown in the following illustrated embodiments can be adopted.

In the laser printer according to the other embodiment, as shown in FIG. 6, for example, a curl detecting means 55 for detecting the curl size is provided above the conveying device 22 and upstream of the sheet conveying direction B. The curl detecting means 55
Two curl sensors 55a and 55b are arranged side by side in the figure. Each of the curl sensors 55a and 55b is, for example, a light transmission type photo sensor that detects passage of the sheet S after image transfer.

The conveyor 22 has a conveyor belt (sheet guide) 3 at the center between the drive roller 36 and the driven roller 37.
Guide rollers 60 and 61 are arranged on the lower side of 5. Then, the conveyor belt 35 is brought into contact with the guide rollers 60 and 61 and is stretched between the drive roller 36 and the driven roller 37. The driven roller 37 is always held at the horizontal position shown in the figure, and is rotatably provided in the arrow direction from the horizontal position by the sheet guide driving means (not shown). For example, a motor or a solenoid is used as the sheet guide driving means. Then, the driven roller 37 is rotated by transmitting the driving force of the sheet guide driving means via a gear to an appropriate holder that holds the driven roller 37. Reference numeral 62 in the drawing is a suction fan that pulls the sheet S passing on the conveyor belt 35 from below.

In the other illustrated embodiment, as shown in FIG. 6, when the curled image-transferred sheet S is conveyed to the fixing device 23, the curl sensors 55a and 55b are used to indicate the passage of the sheet S. When both are detected, the control means (not shown) determines that the degree of curl is large based on the detection result, and as shown in FIG. 7, the sheet guide driving means is operated to move the driven roller 37 downward. Then, the conveyor belt 35 is bent at the positions of the guide rollers 60 and 61 to lower the fixing device 23 side to the lowest position of the solid line to form a large drop h with the sheet inlet 53.
Then, direct the leading edge of the sheet S toward the fixing nipping portion 52,
The conveyance belt 35 advances the fixing nip portion 52. On the other hand, when only the lower curl sensor 55b detects the passage of the sheet S, the control means determines on the basis of the detection result that the degree of curl is small, and the sheet guide driving means is operated to move the driven roller 37. The conveyor belt 35 is turned upward, the conveyor belt 35 is bent slightly upward, and the fixing device 23 side is raised to an intermediate position indicated by a chain line. Then, the drop h is changed to be smaller, and the leading end of the sheet S is directed to the fixing dip portion 52.

[0027]

Therefore, according to the first aspect of the invention, when the sheet edge detecting means detects the leading edge or the trailing edge of the sheet, the regulating means drives the regulating means to the regulating position to lift the sheet. Since the sheet is pressed, even if the sheet after the image transfer is curled, the sheet after the image transfer can be smoothly conveyed to the fixing device without causing troubles such as jamming and image rubbing.

According to the second and third aspects of the present invention, the sheet guide driving means is driven by the control means based on the detection result of the curl detecting means so that the sheet inlet of the fixing device and the fixing device side of the sheet guide are connected to each other. Even if the sheet is curled even if it is curled, the sheet after image transfer can be smoothly fixed without causing troubles such as jams and image rubbing. Can be transported to.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a laser printer which is an embodiment of the present invention.

FIG. 2 is a perspective view of a roller that is a regulating unit in the laser printer.

FIG. 3 is a floating regulation state diagram on the leading edge side of the sheet after image transfer by the roller.

FIG. 4 is a view showing a state in which the rollers are in a state where the rear end side of the sheet after the image transfer by the roller is restricted.

FIG. 5 is a schematic configuration diagram of an entire internal mechanism of this laser printer.

FIG. 6 is a main part configuration diagram of a laser printer according to another embodiment of the present invention.

FIG. 7 is an adjustment state diagram of a drop between the sheet entrance of the fixing device and the fixing belt side of the conveyance belt in the laser printer.

[Explanation of symbols]

 23 Fixing Device 35 Conveyor Belt (Sheet Guide) 36 Drive Roller 37 Driven Roller 38 Sheet Edge Detecting Means 40 Roller (Regulating Means) 53 Sheet Inlet 55 Curl Detecting Means 60/61 Guide Roller S Sheet h Droplet i Sheet Conveying Direction

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area G03G 15/20 102

Claims (3)

[Claims] 1. An electrophotographic recording apparatus for placing a sheet after image transfer in a fixing device to fix the transferred image on the sheet, and a sheet end detecting means for detecting a front end and a rear end of the sheet after the image transfer. A regulating means which is provided downstream of the sheet end detecting means in the sheet conveying direction and is movable between a regulating position for restraining the rising of the sheet before entering the fixing device and a retracting position for releasing the retainer; An electrophotographic recording apparatus, comprising: a control unit that drives the restriction unit to the restriction position at a predetermined timing when the front end or the rear end of the sheet is detected by the unit. 2. An electrophotographic recording apparatus in which a sheet after image transfer is guided by a sheet guide into a fixing device, and the image transferred on the sheet is fixed by the fixing device. Curl detection means for detecting the curl, sheet guide driving means for changing the drop between the sheet inlet of the fixing device and the fixing device side of the sheet guide, and the sheet guide driving means based on the detection result of the curl detecting means. And a control means for adjusting the head.
Electrophotographic recording device. 3. The sheet guide is a conveyor belt for conveying a sheet, the conveyor belt is brought into contact with a guide roller, and is stretched between a driving roller and a driven roller, and the driven roller is moved by the sheet guide driving means. The electrophotographic recording apparatus according to claim 2, wherein the conveyance belt is bent at the position of the guide roller to change the drop.