JPH10171290A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic device which carries and ejects a transfer material without stopping it even in case abnormal conditions occur in a torque absorbing mechanism. SOLUTION: To paper ejection roller 4, a first driving device and a second driving device are drive-connected. The first driving device is equipped with a torque limiter 10 for making a speed difference so that a speed V2 at which the transfer material 9 is carried by it is higher than a speed V1 at which it is carried by a pair of fixing rollers 1 and 2, and for absorbing the speed difference between the paper ejection roller 4 and the fixing part. The second driving device is equipped with a one-way clutch 12 for making the speed at which the transfer material is carried by it almost equal to the speed at which the transfer material is carried by the fixing part, and for absorbing a speed difference between the first driving device and itself.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing means for holding a transfer material by being driven to rotate by a driving device, and fixing an unfixed toner image carried on the transfer material to the transfer material. The present invention relates to an electrophotographic apparatus such as a printer, a copying machine, a facsimile, and the like, which has a paper discharge conveyance unit that is drivingly connected to a driving device that rotationally drives the fixing unit and conveys the transfer material that has passed through the fixing unit toward a discharge unit. Things.

[0002]

2. Description of the Related Art Electrophotographic devices of the above type are known.
In this type of electrophotographic apparatus, a transfer material feeding speed (hereinafter, referred to as a linear speed) from a fixing unit to a paper discharging unit is set to be substantially the same. For this reason, when the conveyance path of the paper discharge unit is relatively long,
The time from when the trailing edge of the paper passes through the fixing section to when the paper is discharged from the discharge port also becomes longer, and therefore, the time from when the operator issues a print instruction operation to when the print is completed, that is, the time for the first print, There was a problem of becoming long.

In order to reduce this problem, Japanese Patent Application Laid-Open No.
In Japanese Patent Application Laid-Open No. 1010, the paper discharging and conveying means is drivingly connected to a driving device with a speed difference at which the transfer material feeding speed is faster than the transfer material feeding speed by the fixing device, and the paper discharging and conveying means has a difference in torque between the paper discharging and conveying means and the fixing means. There has been proposed an electrophotographic apparatus provided with a torque absorbing mechanism that absorbs the light. In this apparatus, when the transfer material is conveyed across the fixing means and the paper discharge conveyance means, the transfer material can be conveyed at a transfer material feed speed by the fixing means without slipping between the paper discharge conveyance means,
When the rear end of the transfer material has passed through the fixing means, the transfer material can be conveyed at the transfer material feeding speed by the high-speed sheet discharging and conveying means, and the advantage of shortening the time of the first print can be obtained.

[0004]

However, in the device described in the above publication, the torque absorbing mechanism deteriorates,
When the torque increase of the paper discharge section occurs, a slip occurs when the input side and the output side of the torque absorbing mechanism should have the same number of revolutions, that is, after the rear end of the transfer material passes through the fixing section,
There has been a problem that the transfer material is not conveyed at the set conveyance speed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic apparatus which can solve the above-mentioned conventional problems and can convey and discharge a transfer material without stopping even when an abnormality occurs in a torque absorbing mechanism.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention holds and transfers a transfer material by being rotationally driven by a driving device, and at this time, removes an unfixed toner image carried on the transfer material. An electrophotographic apparatus comprising: a fixing unit configured to fix a transfer material; and a paper discharge conveyance unit that is drivingly connected to a driving unit that rotationally drives the fixing unit, and conveys the transfer material that has passed the fixing unit toward a discharge unit. The discharge / conveyance means has a speed difference at which the transfer material feed speed is higher than the transfer material / feed speed by the fixing means, and the discharge / conveyance means absorbs the speed difference from the fixing means. A first driving device having a torque absorbing mechanism, and a speed difference absorbing mechanism in which a transfer material feeding speed is substantially the same as the transfer material feeding speed by the fixing unit and which absorbs a speed difference between the first driving device and the first driving device. The second drive device provided with Bets is characterized in that it is drivingly connected.

The present invention is effective when both the first driving device and the second driving device are drivingly connected to a driving unit that rotationally drives the fixing unit. The present invention is effective when the speed difference absorbing mechanism between the first drive transmission device and the second drive transmission device is a one-way clutch.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing the relationship between a fixing unit and a paper discharge unit in the electrophotographic apparatus according to the present invention. FIG.
In the figure, reference numeral 1 denotes a fixing roller as a fixing unit, reference numeral 2 denotes a pressing roller which is pressed against the fixing roller 1, and reference numerals 3 and 4 denote a paper discharging and conveying means for discharging the transfer material 9 which has passed through the fixing unit. It is a discharge roller pair. A driving gear 5 is fixed to the shaft of the fixing roller 1, and the driving gear 5 is drivingly connected to a driving unit (not shown) and is driven to rotate clockwise. The driving of the fixing roller 1 is transmitted to the pressure roller 2 by friction between the rollers or friction between the paper and the roller, and the pressure roller 2 is driven to rotate counterclockwise.

On the other hand, the lower discharge roller 4 of the pair of discharge rollers 3 and 4 is driven to rotate, and the upper discharge roller 3 is a driven roller. In this case, a gear 6 is attached to a shaft of the lower sheet discharging roller 4, and the gear 6 is drivingly connected to the driving gear 5 via a first driving device. As shown in FIGS. 1 and 2, the first drive device of the present embodiment has two stages: an idle gear 7 meshing with the drive gear 5, a small-diameter gear 8 a meshing with the gear 7, and a large-diameter gear 8 b meshing with the gear 6. The idle gear 8 is a gear. Accordingly, the torque from a driving unit (not shown) is applied to the fixing roller 1 via the driving gear 5 and transmitted to the idle gear 7, and further increased in speed by the idle gear 8 and applied to the lower discharge roller 4.
At this time, the speed at which the transfer material 9 is conveyed by the fixing roller 1 and the pressure roller 2, that is, the linear speed of the fixing roller 1 is set to V1, and the speed at which the transfer material 9 is conveyed by the discharge roller pairs 3 and 4, ie, the lower speed. Assuming that the linear velocity of the paper discharge roller 4 is V2, V1 is increased as described above, so that V1 <V2. Further, the holding force of the transfer material 9 by the fixing roller 1 and the pressure roller 2 is set to be larger than that of the paper discharge rollers 3 and 4.

The feed speed of the transfer material 9 by the fixing roller 1 and the pressure roller 2 is almost the same as the feed speed of the image forming section (not shown), whereas the feed speed by the discharge rollers 3 and 4 is the same. Since the transfer speed of the transfer material 9 is higher than that of the fixing roller pairs 1 and 2, quick discharge is possible. However, when the transfer material 9 is conveyed while being held between the fixing roller pairs 1 and 2 and the discharge roller pairs 3 and 4, the fixing roller pair 1 and 2 have a large clamping force even if there is a speed difference between the two. Transported at a linear velocity V1 of
Slip occurs between the transfer material 9 and the pair of discharge rollers 3 and 4. If the linear velocity difference (V2−V1) between V1 and V2 is large to some extent, the slip amount may excessively rub the transfer material 9, causing a problem such as traces of the roller of the transfer material 9. A torque limiter 10 is interposed between the gear 6 and the lower discharge roller 4 as a torque absorbing mechanism for absorbing a linear torque difference between the sheet discharge roller 2 and the pair of discharge rollers 3 and 4. As shown in FIG. 2, the torque limiter 10 is attached to the shaft 4a of the lower sheet discharge roller 4, and the gear 6 is provided on the outer periphery thereof. Assuming that the set torque of the torque limiter 10 is μ, the friction coefficient of the lower discharge roller 4 is μ, the pressing force of the upper discharge roller 3 is N, and the outer diameter of the lower discharge roller 4 is r.
Although it is smaller than μNr, it is set to be larger than the torque T when the torque for driving the lower discharge roller 4 is T.

In the electrophotographic apparatus having the above structure, the linear velocity V1 of the fixing roller pairs 1 and 2 and the linear velocity V2 of the discharge roller pairs 3 and 4 are V
1 <V2, and a torque limiter 10 between the gear 6 and the lower discharge roller 4 with the torque set as described above.
As shown in FIG. 3, the transfer material 9
Does not slip between the transfer material 9 and the discharge roller pairs 3 and 4 even when the transfer material 9 is pinched and conveyed between the fixing roller pairs 1 and 2 and the discharge roller pairs 3 and 4. That is, since the set torque of the torque limiter 10 is smaller than the above-mentioned μ · N · r, when the transfer material 9 is conveyed at the linear speed V 1, the linear speed difference (V2−V1) is absorbed by the torque limiter 10 and Slip does not occur between the sheet 9 and the pair of sheet discharge rollers 3 and 4. As shown in FIG. 4, when the rear end of the transfer material 9 passes through the fixing roller pairs 1 and 2, the transfer material 9 is nipped and conveyed by the discharge roller pairs 3 and 4. At this time, the set torque of the torque limiter 10 is set. Is set to be larger than the torque T,
The transfer material 9 is discharged at a high linear velocity V2 without absorbing the torque T.

With such a configuration, the transfer material 9
When the trailing edge of the transfer material 9 passes through the fixing roller pairs 1 and 2, the transfer material 9 is discharged at a high speed, so that the time of the first print can be shortened. Moreover, even if the linear velocity V of the discharge roller pairs 3 and 4 is higher than the linear velocity V1 of the fixing roller pairs 1 and 2, the linear velocity difference (V2-V1) can be absorbed by the torque limiter 10, and the linear velocity difference can be reduced. There is no problem caused by the provision.

The above is the configuration and operation of the first driving device. When the operation of the torque limiter 10 is abnormal, that is, when the magnetic force of the magnetic material controlling the transmission torque decreases and the frictional force of the sliding member decreases. When the torque transmitted from the torque limiter 10 becomes smaller than the driving torque T of the paper discharge roller 4 when the torque becomes smaller than the initial set torque due to a decrease or when the bearings and the like deteriorate with time, the linear velocity V of the paper discharge roller 4 is originally required.
2, the torque limiter 10 slips after the rear end of the transfer material 9 passes through the fixing unit, and no torque is transmitted to the first drive device, so that the transfer material stops.

Therefore, according to the present invention, the shaft 4a of the discharge roller 4 is provided.
A gear 11 meshing with a small-diameter gear 8a of a two-stage idle gear 8 as a second driving device, and a one-way clutch 12 as a speed difference absorbing mechanism between the gear 11 and the shaft 4a of the discharge roller 4. Is provided. Thus, as described above,
When the torque limiter 10 slips and the transfer material stops without transmitting the torque to the first drive path, the second driving device that passes through the gear 11 without passing through the torque limiter 10 always outputs the linear velocity V1. Is transmitted to the discharge roller 4, the transfer material 9 is conveyed and discharged at a linear velocity V1 by the second driving device as shown by a dotted arrow in FIG. Although the second driving device is drivingly connected to the driving portion of the fixing roller 1, the second driving device may be drivingly connected to another driving portion, but both the first and second driving devices are connected to the driving portion of the fixing roller 1. The drive connection to the drive unit is simple and advantageous.

When the torque limiter 10 is operating normally, the first drive unit alternately repeats the linear velocity of the discharge roller 4 at V1 and V2, while the second drive The apparatus always applies V to the discharge roller 4.
In order to act to give rotation corresponding to the linear velocity of 1,
There may be a case where a difference in linear velocity given between the first and second drive paths to the paper discharge roller 4 occurs. However, when the linear velocity of the discharge roller 4 is V2, the difference between the two linear velocities (V2-V1) is absorbed between the shaft 4a of the discharge roller 4 and the gear 11. That is, the linear speed difference relatively idles due to the one-way clutch 12 built in the inner diameter portion of the gear 11, so that the linear speed difference does not occur.

Although the present embodiment has been described with reference to a drive device using a gear train, a drive device partially using a pulley and a timing belt may be used.

[0017]

According to the first aspect of the present invention, in an electrophotographic apparatus having a drive mechanism for shortening the time of the first print, when a torque absorbing device such as a torque limiter does not function normally, that is, torque transmission. When it is no longer possible to transfer the transfer material, the drive is transmitted by another drive path that does not pass through the transfer material. In this case, since the paper is conveyed at the same speed as the linear speed of the image forming / fixing unit, the paper cannot be conveyed at an increased speed.However, there is a problem that the transfer material stops in the conveyance path and is not conveyed or discharged. It is possible to prevent.

According to the second aspect of the present invention, since the first and second driving devices are also driven and connected to the driving portion of the fixing roller 1, the configuration can be simplified and provided at a low cost. According to the configuration of the third aspect, since the one-way clutch is used as the speed difference absorbing mechanism between the first and second drive transmission devices,
The above problem can be prevented with a simple configuration.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the relationship between a fixing unit and a paper discharge unit of an electrophotographic apparatus according to the present invention.

FIG. 2 is an explanatory plan view of FIG. 1;

FIG. 3 is an explanatory diagram showing a state in which a transfer material is pinched and conveyed by a crotch between a fixing roller pair and a paper discharge roller pair.

FIG. 4 is an explanatory diagram illustrating a state in which a rear end of a transfer material has passed through a fixing roller pair.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Upper discharge roller 4 Lower discharge roller 5 Drive gear 6 Gear 7 Idle gear 8a Small diameter gear 8b Large diameter gear 9 Transfer material 10 Torque limiter 11 Gear 12 One-way clutch

Claims (3)

[Claims] A fixing device for fixing the unfixed toner image carried on the transfer material onto the transfer material by nipping and conveying the transfer material by being rotationally driven by a driving device; and rotating the fixing device. An electrophotographic apparatus, which is connected to a driving unit that drives the recording medium and that conveys the transfer material that has passed through the fixing unit toward a discharge unit. A first driving device having a speed difference that is higher than a transfer material feeding speed by the fixing unit, and having a torque absorbing mechanism in the sheet discharging and conveying unit for absorbing a speed difference from the fixing unit; A second driving device having a feeding speed substantially equal to the transfer material feeding speed of the fixing unit and having a speed difference absorbing mechanism for absorbing a speed difference from the first driving device is drivingly connected. Electrophotography characterized by the following: Location. 2. The electrophotographic apparatus according to claim 1, wherein the first driving device and the second driving device are both drivingly connected to a driving unit that rotationally drives the fixing unit. Electrophotographic equipment. 3. The electrophotographic apparatus according to claim 1, wherein the speed difference absorbing mechanism between the first drive transmission device and the second drive transmission device is a one-way clutch. Electrophotographic equipment.