JP2002255402A - Recording medium carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium carrying device eliminating an error in carrying a recording medium in an imaging device and maintaining a constant printing writing position. SOLUTION: An auxiliary carrying roller 11 stops rotating once at the time E when it deflects with the end hitting a resist roller 12 for timing printing writing and the auxiliary carrying roller 11 having a carrying speed set to be faster starts rotating in synchronization with the resist roller 12 at starting recarrying. Thus, the recording medium is surely bitten into the resist roller 12 and stably carried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium conveying device for conveying a recording medium in an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus has used a recording medium conveying device for keeping a print start position constant.

[0003] A conventional recording medium transport device will be described below.

FIG. 3 is an outline view of a conventional image forming apparatus, and FIG.
4 is a timing chart of a conventional recording medium transport device. In FIG. 3, reference numeral 5 denotes a photoreceptor having a base material made of aluminum or the like, and a photoreceptor layer coated on the outer peripheral surface thereof in a thin film shape and rotating in a direction indicated by an arrow A; A charging unit for charging the photoconductor 5; a laser beam 7 for irradiating the charged photoconductor 5 to form an electrostatic latent image; and 8 a toner image of the electrostatic latent image formed on the photoconductor 5 with toner. A developing unit 9 for transferring the toner image visualized by the developing unit 8 onto the recording medium 4; a cleaning roller 10 for removing the toner remaining on the surface of the photoconductor 5; The fixing device fixes the toner on the recording medium 4 while heating the recording medium 4 that has been heated.

[0005] Next, 1 is configured to be movable in the direction indicated by the arrow B, contacts the uppermost recording medium 4 of the stacked recording media 4, and conveys the uppermost recording medium 4 stacked. The pull-in roller 1 has a shaft 14
Is mounted to be able to swing freely. Reference numeral 2 denotes a separation / conveyance roller for separating / conveying the recording medium 4 conveyed by the pull-in roller 1, and a rotating shaft 14 provided in the image forming apparatus main body.
Fixed to. Reference numeral 15 denotes a holding member attached to the rotating shaft 14 via a rotatable member.
And a multi-conveyance prevention roller that rotates in a direction opposite to the separation / conveyance roller 2. Reference numeral 12 denotes a registration roller that feeds the recording medium 4 to the image forming unit 20 in synchronization with the print timing. Reference numeral 11 conveys the recording medium 4 to the registration roller that has stopped rotating, presses the leading end thereof, and holds it in a bent state. The auxiliary transport roller 22 protrudes into the transport path, and
Lever (not shown in the figure)
And a photo interrupter (omitted in the figure)
This is a paper sensor constituted by:

[0006] First, the operation of the image forming apparatus using the recording medium transport device configured as described above will be described.

The photoconductor 5 rotating in the direction indicated by the arrow A is uniformly charged by the charger 6, and the charged photoconductor 5 is charged.
Is irradiated with a laser beam 7 to form an electrostatic latent image. Then, the electrostatic latent image is visualized by a developing device 8 with toner,
The visualized toner image is transferred to the recording medium 4 by the transfer means 9. The toner image is fixed by the fixing device 13, and the image formation is completed.

Next, the operation of the recording medium transport device will be described.

The rotation shaft 14 is rotated by a motor (not shown) provided in the main body of the image forming apparatus, and the separation / conveyance roller 2 is rotated with the rotation of the rotation shaft 14. In addition, the rotation of the separation / conveyance roller 2 causes the pull-in roller 1 to rotate via a drive transmission means (omitted in the figure). In this state, the holding member 15 is rotated by a lifting mechanism (not shown) in a direction indicated by an arrow B, and the rotation of the holding member 15 causes the pull-in roller 1 to be stacked on the recording medium 4. And the uppermost recording medium 4 is conveyed between the separation conveyance roller 2 and the multiple conveyance prevention roller 3, where only the uppermost recording medium 4 is separated by the separation conveyance roller 2. Auxiliary transport roller 11
And the second and subsequent recording media 4 are prevented from being transported by the multiple transport prevention roller 3. And the paper sensor 22
After detecting the leading end of the recording medium 4, in FIG.
Is pressed against the resist roller 12 which has stopped rotating, and the recording medium 4 stops in a state where the recording medium 4 is bent.

The toner image formed on the photoreceptor 5 and the print start position of the recording medium 4 are aligned with each other at a time point D in FIG.
The registration roller 12 starts rotating and the recording medium 4 in a bent state is bitten by the restoring force of the recording medium 4, and the image forming unit 2 between the photoconductor 5 and the transfer unit 9 is moved.
Transported to zero. At this time, the auxiliary transport roller 11 and the separation transport roller 2 and the like rotate following the movement of the recording medium 4.

[0011]

However, in the above-mentioned conventional configuration, the difference in restoring force due to the type and thickness of the recording medium 4 and the variation of the transport time make the registration roller unstable, so that the recording medium 4 becomes unstable. There has been a problem that the writing position shifts or a transport error occurs.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a recording medium transporting apparatus which stabilizes the engagement of a recording medium with a registration roller and stabilizes a print start position.

[0013]

According to a first aspect of the present invention, there is provided a registration roller for holding and conveying a recording medium, and a registration roller disposed upstream of the registration roller for holding the recording medium. An auxiliary transport roller for transporting the recording medium to the registration roller, a sensor disposed upstream of the registration roller to detect the presence of the recording medium, and a state in which the recording medium hits the registration roller after the sensor detects the recording medium and the recording medium is bent. And a control means for controlling the rotation of the auxiliary transport roller so as to temporarily stop it, and simultaneously rotating both the registration roller and the auxiliary transport roller for a specific period at the start of re-transportation.

According to a second aspect of the present invention, there is provided the recording medium transport apparatus according to the first aspect, wherein the auxiliary transport roller is configured to rotate at a higher transport speed than the registration roller. It is.

According to a third aspect of the present invention, there is provided the recording medium transport apparatus according to the first aspect, wherein the auxiliary transport roller includes a clutch, and the control means controls the registration roller and the auxiliary transport roller when re-transportation is started. Are rotated simultaneously for a specific period, and then only the registration roller is rotated.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention is a registration roller for nipping and transporting a recording medium, and an auxiliary transport roller disposed upstream of the registration roller for nipping and transporting the recording medium to the registration roller. A sensor disposed upstream of the registration roller to detect the presence or absence of a recording medium;
After the sensor detects the recording medium, the rotation of the auxiliary transport roller is controlled so that the recording medium collides with the registration roller and temporarily stops when the recording medium is bent, and both the registration roller and the auxiliary transport roller are specified at the start of re-transport. And a control means for simultaneously rotating the recording medium during the period, and has an action of forcibly engaging the recording medium with the registration rollers.

According to a second aspect of the present invention, there is provided the recording medium transport apparatus according to the first aspect, wherein the auxiliary transport roller is configured to rotate at a higher transport speed than the registration roller. This has the effect of increasing the amount of flexure of the recording medium between the registration roller and the auxiliary transport roller, increasing the restoring force, and ensuring that the recording medium bites into the registration roller.

According to a third aspect of the present invention, there is provided the recording medium transport apparatus according to the first aspect, wherein the auxiliary transport roller includes an (electromagnetic) clutch, and the control means controls the registration roller and the transfer roller at the start of re-transport. After rotating both of the auxiliary transport rollers for a specific period at the same time, only the registration rollers are rotated.After the registration rollers bite the recording medium, the auxiliary transport rollers follow the movement of the recording medium. This has the effect of eliminating the bending of the recording medium between the registration roller and the auxiliary transport roller.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a block diagram of a recording medium conveying device according to an embodiment of the present invention, and FIG. 2 is a timing chart of the same. The description will be given below with reference to these drawings. Here, components having the same configuration as the conventional technology are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 1, reference numeral 40 denotes a control means; 41, an electromagnetic clutch for disconnecting the transmission of the driving force to the registration roller 12; 42, an electromagnetic clutch for disconnecting the transmission of the driving force to the auxiliary transport roller 11; Is the registration roller 1
2, a motor for applying a driving force to the auxiliary transport roller 11, etc.
4 is a timer. The control means 40 receives signals from the paper sensor 22 and the timer 44 and
1 and 42, the motor 43, the rotating shaft 14, and the like.

Next, the operation of the recording medium transport device will be described.

The rotation shaft 14 is rotated by the motor 43, and the separation and conveyance roller 2 is rotated with the rotation of the rotation shaft 14. The pull-in roller 1 is driven by a rotation of the separation / conveyance roller 2 via a drive transmission means (not shown).
Also rotate. Further, since the control means 40 has the electromagnetic clutch 42 in the connected state, the auxiliary transport roller 11 also rotates. In this state, the holding member 15 is moved by the arrow B by the elevating mechanism.
, The pull-in roller 1 comes into contact with the uppermost portion of the stacked recording media 4 with the rotation of the holding member 15, and the uppermost recording medium 4 is prevented from being multiplex-conveyed with the separation-conveying roller 2. The recording medium 4 is conveyed between the auxiliary conveyance roller 1 and the uppermost one recording medium 4 by the separation conveyance roller 2.
1 and the second and subsequent recording media are prevented from being transported by the multiple transport prevention roller 3. And the paper sensor 22
After detecting the leading end of the recording medium 4, the auxiliary transport roller 11 rotates a fixed amount until the point E in FIG. 2, and presses the leading end of the recording medium 4 against the registration roller 12, which stops rotating, to deflect the recording medium 4. When the control means 40 is in the state of being
By cutting 2, the auxiliary transport roller 11 stops.

Then, at time F in FIG. 2, the control means 40 simultaneously connects the electromagnetic clutches 41 and 42 to the registration roller 12 by aligning the image on the photoreceptor 5 with the print start position of the recording medium 4. The auxiliary transport roller 11 starts rotating synchronously. Since the conveying speed of the auxiliary conveying roller 11 is set to be higher than that of the registration roller 12, the recording medium 4 held in a bent state is further bent, the restoring force is increased, and the recording medium 4 is forcibly engaged with the registration roller. In rare cases, the image forming unit 20 between the photoconductor 5 and the transfer unit 9
Transported to At this time, at time point G in FIG. 2 immediately before the leading end of the recording medium 4 reaches the image forming section, the control means 40 disconnects the electromagnetic clutch 42 so that the auxiliary transport roller 11 is driven to rotate, and the auxiliary transport roller 11 Roller 12
During the transfer of the toner image on the photoconductor 5 to the recording medium 4, the distortion of the recording medium 4 during the transfer of the toner image to the recording medium 4 is prevented, and an image disorder called a shock line caused by the elimination of the bending of the recording medium 4 is prevented.

[0025]

As described above, according to the first aspect of the present invention, a registration roller for nipping and conveying a recording medium is provided.
An auxiliary transport roller disposed upstream of the registration roller to pinch the recording medium and transport the recording medium to the registration roller; a sensor disposed upstream of the registration roller to detect the presence or absence of the recording medium; Control means for controlling the rotation of the auxiliary transport roller so that the recording medium is temporarily stopped in a state in which the recording medium is deflected against the resist roller, and simultaneously rotates both the resist roller and the auxiliary transport roller for a specific period at the start of re-transport. And has the function of forcibly engaging the recording medium with the registration roller, thereby preventing image formation failure due to mis-engagement of the recording medium with the registration roller, and stabilizing the image formation position. Can be.

According to a second aspect of the present invention, there is provided the recording medium transport apparatus according to the first aspect, wherein the auxiliary transport roller is configured to rotate at a higher transport speed than the registration roller. Has the effect of increasing the amount of flexure of the recording medium between the registration roller and the auxiliary transport roller, increasing the restoring force, and ensuring that the recording medium bites into the registration roller. It is possible to prevent image formation failure due to a recording medium biting error and to stabilize the image formation position.

According to a third aspect of the present invention, there is provided the recording medium transport apparatus according to the first aspect, wherein the auxiliary transport roller includes a clutch, and the control means controls the registration roller and the auxiliary transport roller when starting re-transport. After rotating both of them at the same time for a specific period, only the registration roller is rotated.After the registration roller bites the recording medium, the auxiliary conveyance roller is driven by the movement of the recording medium, so that the registration roller and the registration roller are rotated. This has the effect of eliminating the deflection of the recording medium between the auxiliary transport rollers, and is called a shock line caused by the elimination of the deflection of the recording medium during the transfer of the toner image on the photoconductor to the recording medium. Image disturbance can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of a recording medium conveyance device according to an embodiment of the present invention.

FIG. 2 is a timing chart of the same.

FIG. 3 is an outline view of a conventional image forming apparatus.

FIG. 4 is a timing chart of a conventional recording medium transport device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Auxiliary conveyance roller 12 Registration roller 22 Paper sensor 40 Control means 41, 42 Electromagnetic clutch 43 Motor 44 Timer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G03G 15/00 518 G03G 15/00 518 F term (reference) 2H072 AA13 AA24 AB07 CA01 CB05 JA02 3F048 AA01 AB01 BA05 BB02 CC03 DA06 DC05 EB22 EB24 EB33 3F049 AA02 DA12 EA01 EA13 EA24 LA01 LB03 3F102 AA01 AB01 BA02 BB02 CA04 CB01 DA08 EA03 EC01 EC07

Claims (3)

[Claims] A registration roller for nipping and transporting a recording medium; an auxiliary transportation roller disposed upstream of the registration roller for nipping and transporting the recording medium to the registration roller;
A sensor disposed upstream of the registration roller to detect the presence or absence of a recording medium; and the auxiliary conveyance so that the recording medium abuts the registration roller after the sensor detects the recording medium and temporarily stops in a state where the recording medium is bent. A recording medium transport apparatus, comprising: control means for controlling the rotation of a roller and rotating both the registration roller and the auxiliary transport roller at the same time for a specific period at the start of re-transport. 2. The recording medium conveying device according to claim 1, wherein the auxiliary conveying roller is configured to rotate at a higher conveying speed than the registration roller. 3. The auxiliary transport roller has a clutch, and the control means rotates both the registration roller and the auxiliary transport roller simultaneously for a specific period at the start of re-transport, and then rotates only the registration roller. Claim 1
The recording medium transport device according to claim 1.