JP3428724B2 - Paper feeder and image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for separating and conveying sheet materials from a sheet material stacking means such as a sheet cassette and an image forming apparatus equipped with the sheet feeding device.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus is provided with a multi-stage paper feeding section in a main body of the image forming apparatus in order to form an image on various sheet materials. In such a conventional image forming apparatus, a large number of sheet feeding / conveying rollers are arranged corresponding to the multi-stage sheet feeding section, and each sheet feeding section is provided with a sheet feeding motor. It was driving the paper feed rollers.

However, even an image forming apparatus having such a multi-stage sheet feeding section does not feed sheets from two sheet feeding sections at the same time. Therefore, originally, it is sufficient to provide one sheet feeding motor for the multi-stage sheet feeding section, which gives a driving force to the sheet feeding and conveying roller.

Therefore, a plurality of clutches are arranged between each sheet feeding / conveying roller of the multistage sheet feeding section and one sheet feeding motor, and the transmission of the driving force of the sheet feeding motor is turned on and off by the clutches.
A technique has been devised in which F is performed to switch the power transmission path that connects the sheet feeding motor and each sheet feeding / conveying roller.

[0005]

However, if such a structure is provided in the sheet feeding section, for example, in the two-stage sheet feeding section, one set of the electromagnetic clutch and the electric parts for driving and controlling the electromagnetic clutch are provided. It becomes necessary, the sheet feeding device, and eventually the image forming apparatus becomes complicated and large in size, the cost becomes high, and further, the probability of occurrence of failure is high.

Therefore, in order to solve the above problems, the drive gear is rotated in the forward and reverse directions by rotating the paper feed motor in the forward and reverse directions, and further, two unidirectional rotation clutches (one-way clutch) are added to the drive gear. ) Are engaged with each other so that the locking directions are opposite to each other, whereby the driving force of the sheet feeding motor can be switched to two gear drive transmission trains, and two sheet feeding units (sheet feeding unit 1 and sheet feeding unit 1 2)
A paper feeding device was further devised, in which the paper feeding device is selected by the forward and reverse rotations of one paper feeding motor. Then, with this technique, the cost and size of the sheet feeding device have been reduced.

However, the above-mentioned conventional example cannot sufficiently cope with the recent cost reduction, and sometimes causes a problem such as an increase in torque of the one-way clutch or a failure. These defects are caused by the product (image forming device)
Cost will be adversely affected, the product life and maintenance will be adversely affected, and the competitiveness of the product will be reduced.

[0008] The applicant of the present invention has disclosed the invention in Japanese Patent Laid-Open No. 64-79450
As disclosed in Japanese Patent Publication No. JP-A-2003-264, as a mechanism for lifting the middle plate of the sheet cassettes arranged in the upper and lower two stages, a drive motor side that rotates forward and backward with a gear train connected to the middle plate without using an electromagnetic clutch. We have already developed an excellent technology for selectively connecting and to the gears attached to the arm that swings in response to the forward and reverse rotations of the drive motor.

However, in this technique, a large number of sheet materials are stacked on the middle plate of the paper feed cassette and the load acting on the middle plate is large. Therefore, the middle plate must be operated against the load. However, the structure was still complicated to apply to the operation of the paper feeding and conveying roller, and the number of parts was large.

Therefore, an object of the present invention is to reduce the size and cost of the sheet feeding device, and further, the image forming apparatus, and to reduce the failure rate of the apparatus by simplifying the structure. And

[0011]

The sheet feeding apparatus of the present invention has been devised in view of the above-mentioned problems of the prior art. In the sheet feeding apparatus for selectively feeding sheets from the upper stage or the lower stage, A drive gear that is rotated forward and backward by a drive source is supported so as to mesh with the drive gear and to swing at a predetermined angle with the rotation center of the drive gear as the swing center. A pair of oscillating gears that move to the oscillating ends, and an upper gear train and a lower gear train that are connected to the oscillating gears at the oscillating ends of any one of the oscillating gears. Side gear train, and an upper stage paper feeding means which is operated by the power of the drive source transmitted through the upper stage gear train, separates and conveys the sheet material, and is transmitted through the lower stage gear train. It is operated by the power of the drive source A lower sheet feeding means for separating and conveying the sheet material, a pair of gear trains connected to the rocking gear at the rocking end of the other rocking gear of the pair of rocking gears, And a conveying unit that rotates in a direction in which the sheet material is conveyed by the power of the drive source transmitted through the pair of gear trains regardless of whether the swing gear rotates forward or backward.

As a result of having the above-mentioned characteristic structure, the paper feeding device of the present invention switches the rotation direction of the drive source and changes the rotation direction of the drive gear, so that the rocking gear rocks and either one of the gear trains is rotated. And the rocking gear is also connected to the gear train. As a result, either one of the sheet feeding means and the conveying means operate.

Further, the image forming apparatus of the present invention is characterized by including the above-mentioned paper feeding device and an image forming means for forming a desired image on a sheet conveyed from the paper feeding device.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Reference Example of the Present Invention FIG. 1 shows a sheet feeding device M according to a reference example of the present invention, which has two pairs of sheet feeding rollers. Of these, FIG. 1A shows the side plate 2
Is removed (see FIG. 1B) to show a side view of the sheet feeding device M, and FIG. 1B is a front view of the sheet feeding device. In these figures, a paper feed motor 3 as a drive source capable of normal and reverse rotation is fixed to a back side plate 1, and a swing gear 5 is attached to a drive gear 4 attached to a rotary shaft of the paper feed motor 3. It is meshed. This oscillating gear 5 has large and small teeth 2 with different numbers of teeth.
Gears, whose gear shafts are supported so as to be slidable in elongated holes formed in the side plate 1 and the side plate 2, and the drive gear 4 is driven by the rotation of the sheet feeding motor 3, that is, the drive gear 4.
It can be swung by a predetermined angle with the center of rotation as the swing center. This swing gear 5 is located at the upper swing end in FIG. 1, and is the upper stage passive gear in the gear train G ₁ including an upper stage passive gear 7, an idle gear 8, an idle stage gear 9, a sheet feeding roller gear 10 and a reversing roller gear 13. It meshes with the gear 7.

An idle gear 8 meshes with the upper passive gear 7, and the idle gear 8 has an idle gear 9.
Are sequentially meshed with each other, the paper feed roller gear 10 is meshed with the large diameter gear portion of the idle stage gear 9, and the reversing roller gear 13 is meshed with the small diameter gear portion of the idle stage gear 9. The gear shafts of the gears 7, 8, 9, 10 and 13 are rotatably supported by the side plates 1 and 2. Among these, the gear shaft 11 of the paper feed roller gear 10 has one end penetrating the side plate 1 and extending in the right direction in FIG. 1B, and the paper feed roller 12 is attached to the tip end thereof. It also functions as an axis.

Also, one end of the gear shaft 14 of the reversing roller gear 13 penetrates the side plate 1 and extends in the right direction in FIG. 1B, and the reversing roller 15 is provided at the tip end of the gear shaft 14 via the torque limiter 16. Is attached and also functions as a reversing roller shaft. The torque limiter 16 operates the gear shaft 14 and the reversing roller 1 when the applied torque is small.
On the other hand, when the acting torque is large, the gear shaft 14 and the reversing roller 15 are slid so that the reversing roller 15 is driven by the paper feeding roller 12. Further, each roller 12, 15 is more than frictional force between the sheet materials.
Since the frictional force acting between the roller and the sheet material is larger, the rollers 12 and 15 reverse the paper feed roller 12 in combination with the function of the torque limiter 16 described above. When a plurality of sheet materials are fed between the roller 15 and the roller 15, only one sheet material is separated and conveyed.

Numeral 25 is a tension spring as an urging means. One end of the tension spring 25 is locked to the side plate 1 on the left side of the drive gear 4 in FIG. 5 is locked to the gear shaft 5 so that the rotation center of the drive gear 4 is substantially the internal dividing point when the swing gear 5 is in the neutral position, that is, when the swing gear 5 does not mesh with any other gear. It is located in. As a result, the tension spring 25 pushes the rocking gear 5 to the upper end when the rocking gear 5 is at the upper end of the elongated hole 6, and when the rocking gear 5 is at the lower end of the elongated hole 6. The swing gear 5 is pressed to the lower end.

2 (a) and 2 (b) show a state in which the rocking gear 5 is connected to the gear train G ₁ on the upper stage side in FIG. 1, whereas the rocking gear 5 is a gear on the lower stage side. It shows a state of being linked to the row G ₂ . That is, the rocking gear 5 has the long hole 6
, The lower stage feeding gear 17 meshes with the swing gear 5, the large-diameter gear portion of the idle stage gear 20 meshes with the lower stage feeding gear 17, and the small-diameter gear of the idle stage gear 20. The parts are sequentially meshed with the lower stage reversing roller gear 21. The gear shafts of the gears 17, 20 and 21 are rotatably supported by the side plates 1 and 2. The gear shaft of the lower feed roller gear 17, that is, the lower feed roller gear shaft 18, extends through the side plate 1 to the left in FIG. 2B, and the lower feed roller 19 is fixed to the tip thereof. Therefore, it also functions as a lower feed roller shaft for rotating the lower feed roller 19. The gear shaft of the lower reversing roller gear 21, that is, the lower reversing roller gear shaft 22 also penetrates the side plate 1 and extends leftward in FIG. 2B, and the lower reversing roller is provided at the tip of the gear shaft 22 via the torque limiter 24. 23 is attached and also functions as a lower-stage reversing roller shaft for rotating the lower-stage reversing roller 23.

The torque limiter 24 cooperates with the lower feed roller 19 and the lower reversing roller 23, and functions similarly to the torque limiter 16 to separate and convey the sheet materials one by one.

The paper feed roller 12 and the torque limiter 1
6 and the reversing roller 15 constitute the upper sheet feeding means K ₁ . Further, the lower-stage sheet feeding roller 19, the torque limiter 24, and the lower-stage reversing roller 23 constitute a lower-stage sheet feeding means K ₂ .

In the above structure, the paper feeding motor 3 is arranged as shown in FIG.
(A) When rotated in the direction of the middle arrow (counterclockwise direction),
The drive gear 4 rotates counterclockwise, causing the swing gear 5 to rotate clockwise. At this time, the oscillating gear 5 receives a force from the drive gear 4 in the direction of the pressure angle of the teeth, and rotates (revolves) around the drive gear 4 in the counterclockwise direction, and its rotation center axis is the upper end of the slot 6. After moving to, the central axis of rotation stops at the upper end of the long hole 6, and then starts rotating (spinning) clockwise.

At this time, the oscillating gear 5 has the tension spring 2
Even if the rotation of the drive gear 4 is stopped, the state of FIG.

The oscillating gear 5 meshes with the upper passive gear 7 by moving to the upper end of the elongated hole 6. Therefore, the rotational driving force of the rocking gear 5 is the idle gear 8, the idle stage gear 9, the paper feed roller gear 10, and the reversing roller gear 1.
It is transmitted to 3. By this drive transmission system, the driving force is transmitted to the upper sheet feeding roller 12 and the reversing roller 15, and the sheet guided between the sheet feeding roller 12 and the reversing roller 15
It is possible to separate and feed one by one.

Next, when the paper feed motor 3 rotates in the direction of the arrow (clockwise) shown in FIG. 2A, the swing gear 5 receives a downward force from the drive gear 4, and the tension spring 25 is pulled. To overcome the pressing force of the upper part of the
Move to the lower end of, and make a driven rotation (rotate counterclockwise) at that position. And the tension spring 25
Becomes the longest during the movement of the rocking gear 5 (the neutral position), contracts when the rotation center axis of the rocking gear 5 reaches the lower end of the elongated hole 6, and presses the rocking gear 5 downward in the drawing.

The small-diameter gear of the swing gear 5 meshes with the lower feed roller gear 17 and rotates the lower reversing roller gear via the idle gear 20. The driving force of the sheet feeding motor 3 is transmitted to the lower sheet feeding roller 19 and the lower sheet reversing roller 23 by the series of drive transmission systems, so that the lower sheet feeding roller 19 is the same as the upper sheet (in the case of FIG. 1). 19 and the lower reversing roller 23 separate and feed the sheet materials one by one.

As described above, by controlling the forward / reverse rotation of the paper feeding motor 3, the upper and lower stages of the paper feeding unit can be switched. Therefore, as compared with the configuration in which the upper and lower sheet feeding is switched by the forward and reverse rotations of the motor using the two one-way clutches in the related art, the two one-way clutches are unnecessary, and the mechanism is simple and there is no fear of failure. Also, the cost can be significantly reduced.

(Embodiment) FIGS. 3 and 4 show an embodiment of the present invention. In these drawings, a swing gear 31 meshes with a drive gear 4 rotated by a paper feed motor 3. There is. The rocking gear 31 is composed of two large and small gear parts having different numbers of teeth, and its gear shaft is supported so as to be slidable in the elongated hole 6 formed in the side plate as in the above-mentioned reference example, and the paper feeding motor 3 That is, as the drive gear 4 rotates, the drive gear 4 can be swung by a predetermined angle about the rotation center of the drive gear 4.
When the swing gear 31 moves to the lower end of the elongated hole 6 (see FIG. 3), the idle gear 32 is attached to the small-diameter gear portion of the swing gear 31.
Mesh with each other, and further idle gear 32, idle gear 3
3, the transport roller gear 34 and the idle gear 35 are in mesh with each other. The idle gear 32 and the idle gear 3
3, the transport roller gear 34, and the idle gear 35 form a gear train G ₃ . Among them, the idle gear 35 is
When the swing gear 31 moves to the upper end of the long hole 6, the swing gear 31
It is designed to mesh with. In addition, the transport roller gear 34
A transport roller (not shown) as a transport means provided on the transport path Z is fixed to the gear shaft of the.

Numerals X and Y in the drawing denote the paper conveying paths of the paper feeding section described in the above reference example. Also, in the figure, A, B, A ',
B ′ indicates the direction in which the oscillating gears 5 and 31 move within the slot 6 of the side plate 1 by the forward and reverse rotations of the drive gear 4.

FIG. 3 is a diagram showing the operation when the paper feed motor 3 rotates counterclockwise, by rotating the paper feed roller 12 (see FIG. 1B) on the paper transport path X side. It shows a state in which the upper sheet is fed. At this time, the swing gear 3
1 is rotated and driven by the drive gear 4 in the direction of arrow A, and the idle gears 32, 33, 35 and the transport roller gear 34 rotate in the direction of arrow in FIG.

As a result, the paper on the transport path Z is transported upward by the transport roller (not shown) provided coaxially with the transport roller gear 34.

Next, when the sheet feeding motor 3 shown in FIG. 4 rotates in the clockwise direction, the swing gears 5 and 31 move to the drive gear 4
By this, it moves and rotates in the directions of arrows A'and B'in the figure. As a result, the paper feed roller on the paper transport path Y side is rotated, and paper is fed from the lower stage. At the same time, the idle gear 35 is rotationally driven by the swing gear 31, and the transport roller gear 3
4 rotates and the transport roller (not shown) rotates, and the transport roller transports the paper on the transport path Z upward as in FIG.

As described above, according to the present embodiment in which the swing gear 31 is provided, the conveying rollers can be rotated in the same direction regardless of the forward / reverse rotation of the paper feeding motor 3. Therefore, even in the case of the mechanism that conventionally uses two one-way clutches instead of the rocking gear 31, the rocking gear 31 of this embodiment is used to simplify the structure of the sheet feeding device and reduce the cost. It is possible to reduce the occurrence rate of failures.

Although the above embodiment has been described by using the example in which the position of the carrying roller is provided on the carrying path Z, the carrying roller provided after the joining of the carrying paths X, Y and Z is the same as the above embodiment. By transmitting the driving force to
The sheet feeding motor 3 can sequentially convey the sheets (sheet materials) conveyed from Y and Z to the next process.

FIG. 5 shows an example of a laser beam printer (image forming apparatus) 100 provided with the above-mentioned paper feeding device, and the construction thereof will be briefly described.

The sheet cassette 4 is of a front loading type which is mounted from the front of the printer 100, and the sheets S stacked on the sheet cassette 4 are sent out in a direction orthogonal to the mounting direction of the sheet cassette 4.

The sheet sent out from the sheet cassette 4 is discharged through an image forming section (image forming means) 101 and a fixing section 109 described later. The image forming unit 101 is provided with a process cartridge 102 that is detachable from the printer 100. The process cartridge 102 has an electrophotographic photosensitive drum 10 as an image carrier.
3, charging means 10 for charging the surface of the photosensitive drum 103
4. Developing means 1 for forming a toner image on the photosensitive drum 103
05, a cleaning unit 106 and the like for removing the toner remaining on the surface of the photosensitive drum 103 are provided. The photosensitive drum 103 is exposed by the image light emitted from the scanner unit 107 according to the image signal.

Further, the image forming section 101 is provided with a transfer roller 108 for transferring the toner image formed on the surface of the photosensitive drum 103 to a sheet. The transfer roller 108 presses the sheet sent from the sheet cassette 4 onto the photosensitive drum 103. By applying a voltage having a polarity opposite to that of the toner image to the transfer roller 108, the toner image on the photosensitive drum 103 is transferred onto the sheet. Transfer to.

The sheet on which the toner image is transferred by the transfer roller 108 is sent to the fixing unit 109. This fixing unit 1
A fixing roller 110 is arranged at 09, and heat and pressure are applied by the fixing roller 110 to fix the toner image on the sheet.

As described above, the toner image is transferred to the sheet sent from the sheet cassette 4 by the process cartridge 102 and the transfer roller 108, and the fixing unit 109 is used.
The toner image transferred by is fixed and discharged.

The relationship between the reference example and FIG. 5 is briefly shown. In FIG. 5, 12 is a paper feed roller, 15 is a reversing roller, 19 is a lower feed roller, and 23 is a lower reversing roller. is there.

As described above, when each of the sheet feeding devices is used in the laser beam printer, the structure of the sheet feeding device is simple and there are few failures, so that the reliability of the laser beam printer can be improved.

[0043]

As described above, in the paper feeding device of the present invention, the oscillating gear is engaged with the drive gear rotated by the drive source to rotate the drive gear in either the forward or reverse direction. By switching, the rocking gear can be selectively connected to any one of the plurality of gear trains, and the paper feeding means and the conveying means connected to the gear train can be operated. Therefore, the paper feeding device of the present invention can eliminate the one-way clutch, which has conventionally been indispensable to use, can simplify the configuration and realize the downsizing, and can reduce the cost, improve the assemblability, and cause the failure rate. Can be reduced.

Further, since the image forming apparatus of the present invention is equipped with the above-mentioned paper feeding apparatus having a low failure rate, it is possible to form a stable image for a long period of time and further improve the reliability of the apparatus. it can.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a sheet feeding device that is a reference example of the present invention. Figure 1
FIG. 1A is a side view in which a part of the paper feeding device is cut away, and FIG.
(B) is a front view of the sheet feeding device.

FIG. 2 is an operation state diagram of the sheet feeding device when the sheet feeding motor is reversed. FIG. 2A is a side view showing an operation state of a side of the sheet feeding device, and FIG. 2B is a view showing an operation state of the front side.

FIG. 3 is a side view in which a part of the sheet feeding device according to the embodiment of the present invention is cut away.

FIG. 4 is a side view showing an operating state of the paper feeding device.

FIG. 5 is a schematic configuration diagram of an image forming apparatus (laser beam printer) that is an embodiment of the present invention.

[Explanation of symbols]

3 Drive Source (Paper Feed Motor) 4 Drive Gears 5, 31 Swing Gear 25 Energizing Means (Tension Spring) 32, 33, 35 Idle Gear 34 Conveyor Roller Gear 100 Image Forming Means (Laser Beam Printer) 101 Image Forming Means (Image Forming unit) G ₁ , G ₂ , G ₃ gear train K ₁ , K ₂ sheet feeding means

Continuation of front page (56) Reference JP-A-5-170346 (JP, A) JP-A-7-81786 (JP, A) JP-A-61-106346 (JP, A) JP-A-4-23742 (JP , A) Japanese Patent Laid-Open No. 7-109041 (JP, A) SAI 63-161240 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B65H 3/06 350 B65H 3/44 312

Claims (2)

(57) [Claims] 1. A paper feeding device for selectively feeding paper from an upper stage or a lower stage, wherein a drive gear rotated forward and reverse by a drive source is meshed with the drive gear and a rotation center of the drive gear is a swing center. And a pair of rocking gears that are supported so as to be rockable by a predetermined angle and that move to either one of the rocking ends depending on the rotation direction of the drive gear, and one of the pair of rocking gears. The sheet material is separated by the power of the drive source transmitted through the upper gear train and the lower gear train that are respectively connected to the rocking gears at the rocking end of the An upper-stage sheet feeding unit that conveys the sheet, a lower-stage sheet feeding unit that is operated by the power of the drive source transmitted through the lower gear train, and separates and conveys the sheet material; and the pair of swings. Swing gear of the other gear The pair of gear trains connected to the rocking gear at the rocking end of the yarn, and the power of the drive source transmitted through the pair of gear trains regardless of the forward / reverse rotation of the rocking gear. A sheet feeding device, comprising: a feeding unit that rotates in a feeding direction. 2. An image forming apparatus comprising: the sheet feeding device according to claim 1; and an image forming unit that forms a desired image on a sheet conveyed by the sheet feeding device.