JPH02158533A - Sheet feeding device for image forming device - Google Patents

Abstract

PURPOSE:To prevent a double feed and increase the life by detecting an output torque of a motor to apply a torque to a return roller, and controlling the output torque of the motor to be constant based on detected information. CONSTITUTION:A pickup roller 1 is put by its own weight on a sheet P mounted on a supply paper tray 4, and a roller 1 and a feed roller 2 are driven to rotate clockwise, while a return roller 3 receives a torque clockwise by a DC motor 30. The roller 3 is applied to the upper roller 2 through an oscillation member 18 by the spring force of a tension spring 20 at a constant pressure. If the sheet P is put between the rollers 2 and 3, the roller 3 rotates counterclockwise to discharge the sheet P to a guide plate 7. However, if two sheets P are put between the rollers 3 and 3, the roller 3 rotates in the direction to return the sheet P because a friction resistance between the upper and lower sheets is small, and the output torque is reduced. This is detected by a torque detector 40, and the output torque is increased and controlled to be constant, so the paper P is returned.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for feeding out sheets stacked on a paper feed tray one by one in an image forming apparatus such as a copying machine or a printer.

LLJ FIG. 10 schematically shows a mechanism for feeding out only the top layer sheet from the stacked sheets.

A pickup roller 01 is pressed onto the stacked sheets, a feed roller 02 is positioned in the paper extrusion direction (arrow 2 direction), and a return roller 03 is pressed against the feed roller 02 from below with appropriate pressure. There is.

In the same figure, a pickup roller 01 and a feed roller 0
2 is rotated clockwise and moves the sheet P in the feeding direction (Z
However, the return roller 03 is constantly receiving torque in the clockwise direction and has a force that attempts to return the sheet P in the return direction (in the direction opposite to arrow Z).

First, the uppermost sheet P among the stacked sheets is pushed out in the feeding direction by the rotational drive of the pickup roller 01, and the sheet P is placed between the feeding roller 02 and the return roller 03.
Then, by rotation of the feed roller 02, the sheet P is sandwiched between the return roller 03 and sent out.

At this time, the return roller 03 is rotated counterclockwise by the II force regardless of the torque in the return direction.

Normally it works as above and 8! Il! ! 1 from sheet
Sheets are fed out one by one.

However, if for some reason the pickup roller 01 pushes out two sheets P, the feed roller 0
Two sheets P are sandwiched between the return roller 03 and the return roller 03.

In such a case, the torque of the return roller 03 in the return direction overcomes the friction between the seat booths and returns the lower paper P in the return direction, and only the upper paper P is sent out one sheet, thereby preventing double feeding. .

Let us analyze the conditions for performing the above operation (discussing the pickup roller 01 while ignoring it).

The symbols now have the following meanings.

N: Pressing force of the return roller 03 T: Reverse torque of the return roller 03 R: Radius of the return roller 03 m: mm of one sheet of paper P μr: Coefficient of friction between the feed roller 02 and the paper P μp:
Coefficient of friction between sheets of paper P First, as shown in FIG.
The feeding force μrN of the feed row 502 in the feeding direction is larger than the sum of the return force T/R of the return roller 03 and the inter-paper resistance μρm.

That is, μr N > T/R 10 μpm, and when transformed into a conditional expression for the reverse rotation torque T of the return roller 03, the following expression is obtained.

T<(μr N-up m) R... (1) When no paper is sandwiched between the feed roller 02 and return roller 03, the coefficient of friction between both rollers is large, so (1)
If the reverse torque T satisfies the formula, the return roller 03 is rotated counterclockwise against the torque T.

Next, as shown in FIG. 12, when two sheets of paper P are sandwiched between the feed roller 02 and the return roller 03,
The conditions for returning the . This is greater than the sum of the inter-sheet resistance force of 2 μpm which is applied by the two sheets P above and below to the sheet P further below.

That is, T/R>tlP N+up m+2μp mr
If the conditional expression for the reverse rotation torque T of the return row 503 is transformed, the following expression is obtained.

T> C11p N+3μp m)R・”(2) Therefore, the reversing torque T of return 0-503 is always (1),
If the value satisfies equation (2), it is possible to prevent double feeding and feed out the sheets P one by one.

Therefore, in the past, a torque limiter was used and the return roller 03
There is an example (Japanese Patent Publication No. 52-34216) in which the torque limiter is pivotally supported via a torque limiter, and the torque T+- at which the torque limiter starts to slip is kept constant as the reversal torque T.

In other words, one sheet of paper P passes through the feed roller 02 and the return roller 03.
, the torque Tr satisfies equation (1) and the torque limiter slips, causing the return roller 03 to rotate counterclockwise and sending out one sheet of paper P.

When the paper P is caught between the two-sheet feed roller 02 and the return roller 03, the torque T of the torque limiter satisfies equation (2) and rotates the return roller 0-03 clockwise, and the lower Push back the paper P to prevent double feeding.

・ However, the value of torque T+- at which the torque limiter starts to shift varies due to manufacturing variations, wear over time, the environment, etc., so the torque T value does not match the theoretical value, resulting in double feeding or feeding errors. Problems such as this may occur.

In order to deal with such torque fluctuations, a mechanism has been considered that detects the torque of the torque limiter and adjusts the pressing force N of the return roller 03, but the mechanism becomes complicated and large, and the torque limiter wears out. cannot be avoided and must be replaced periodically.

The present invention has been made in view of this point, and its object is to provide a sheet feeding device that has a simple structure, is free from the risk of double feeding, and has a long life.

That is, the present invention includes a feed roller that is rotationally driven in the sheet feeding direction, a return roller that is pressed against the feed roller,
A motor that applies torque to the return roller in the sheet return direction, a torque detection means that detects the output torque of the motor, and a control means that constantly controls the output torque of the motor based on the detection information of the torque detection means. This is a sheet feeding device for a picture frame forming device.

(1) above by detecting the output torque of a motor that applies torque to the return roller and controlling the output torque of the motor to a constant level based on the detected information.

It is possible to maintain the value of the reverse rotation torque T that satisfies equation (2), prevent double feeding, and perform smooth sheet feeding.

The output torque of the motor is detected and controlled, so there is no change over time and the reversing torque is always constant.
can be obtained, significantly extending the service life compared to torque limiters.

In addition, by transmitting the motor drive through a spring and detecting the change in the spring with a potentiometer to detect the motor's output torque, the mechanism can be simplified, making it possible to reduce the size and cost. , reliability can also be high.

An embodiment of the present invention illustrated in FIGS. 1 to 4 will be described below.

FIG. 1 shows the basic configuration of a sheet feeding device of a copying machine according to the present embodiment, in which sheets P are stacked on a bottom plate 5 supported by a paper feed tray 4 so as to be movable up and down.

The bottom plate 5 is suspended by a wire 6, and the height of the top layer sheet P is adjusted by appropriately lifting the laminated sheet by pulling the wire 6.

A pickup roller 1 is in contact with the top layer sheet P under its own weight, a feed roller 2 is positioned in the paper extrusion direction, and a return roller 3 is pressed against the lower end of the feed roller 2.

Feed roller 2. On the downstream side of the return roller 3, guide plates 7 are disposed above and below.

The top layer of the laminated sheet is pushed out by the rotation of the pickup row 51, and its tip is transferred to the feed roller 2.
．． It is sandwiched between the return rollers 3.

The sheet P is fed out by rotation of the feed roller 2 while being sandwiched between the feed roller 2 and the return roller 3, and the fed sheet P is guided by a guide plate 7 to a copying process.

Pick up roller 1. The drive 1j14 of the feed roller 2 and return roller 3 is shown in FIG.

A rotating shaft 11 is supported passing through both sides of the frame 10, which is bent into an opening shape, and the feed roller 2 is integrally fitted onto the rotating shaft 11.

The rotating shaft 11 is rotationally driven by a motor (not shown),
The feed roller 2 is rotated together.

A pair of rocking plates 12 are located close to both sides of the feed roller 2.
Its base end is pivotally supported by a rotating shaft 11, and a rotating shaft 13 is rotatably installed between the distal ends of the same pair of rocking plates 12, and the pickup roller 1 is mounted on the rotating shaft 13.
l! It is worn.

Therefore, the pickup roller 1 can rotate itself and can swing as a whole around the rotating shaft 11.

Gears 14.15 of the same shape are fitted integrally with the rotating shaft 11 and the rotating shaft 13 on the inside of one of the swing plates 12, and between the two gears 14.15, the gears 14.15 and 14.
．． A gear 16 that meshes with the gear 15 is rotatably supported on the rocking plate 12.

Therefore, by rotationally driving the rotary shaft 11 in the clockwise direction (in the direction of the arrow in FIG. rotate at the same speed.

Feed roller 2. The clockwise rotation of the pickup roller 1 is the paper feeding direction.

The return roller 3, which is pressed against the feed roller 2 from below, is supported by its rotation @17 being biased upward by the arm portion 18a of the swinging member 18.

The swinging member 18 has a mouth shape in which left and right arm portions 18a are connected by a connecting portion 18b, and a support shaft 19 penetrates and supports the base end portions of the left and right arm portions 18a. The swinging member 18 can swing around the center.

One end of a tension spring 20 is locked to the connecting portion 18b of the swinging member 18, and the swinging member 18 is always biased clockwise by the tension spring 20, so that the tips of the left and right arms 18a are The rotation shafts 17 on both sides of the pickup roller 1 are urged upward and supported.

This upward force causes the return roller 3 to move forward to the feed roller 2.
It is now under pressure.

Below the fixed frame 10, there is also a mouth-shaped fixed frame 21, and a rectangular notch is vertically provided in the protruding portions 21b that protrude upward from the upper edges of both side bodies 21a. The rotary shaft 17 is inserted into the notch from above.

Therefore, the pickup roller 1 is restricted from moving back and forth, and can freely move up and down only in the up and down direction.

The support shaft 19 that supports the swinging member 18 has both ends fixed to the side body 21a of the fixed frame 21.

Further, one end of the tension spring 20 is connected to a fixed frame 21.
It is locked to.

A DC motor 30 is arranged below the fixed frame 21, and its drive shaft 30a is connected to a gear shaft 32 via a flexible joint 31.

The gear shaft 32 is rotatably supported by a fixed frame 33 via a bearing 34, and a gear 35 is fitted to an end thereof.

A torque detector 40 including an input gear 41 that meshes with the gear 35 is disposed above the gear 35 and supported by the fixed frame 33 and a fixed portion (not shown).

An output shaft 42 of the torque detector 40 is supported by a fixed frame 33 via a bearing 36, and an end thereof is connected to the rotary shaft 17 via a flexible joint 37.

Therefore, the DC motor 30 is driven by the gear 35. The torque is transmitted to the rotating shaft 17 via the torque detector 40 and rotates the return roller 3 clockwise.

The structure of the torque detector 40 used here will be explained below with reference to FIG.

The torque detection 77340 is roughly divided into fixed housing 4
3. Rotating part 45. A rotating part 45 is rotatably supported by a fixed housing 43 via a bearing 44 and rotates at the same time. ! 1I45, the output shaft 42 is rotated via a torsion spring 50.

The rotating part 45 is constructed integrally with the input gear 41, and has a cylindrical rotating housing 4 on both sides of the input gear 41.
6.47 is fixed.

The rotation housing 46 on the output shaft side has the output shaft 4 therein.
The output shaft 42 is rotatably supported via a bearing 48.

Note that the exposed portion of the output shaft 42 is connected to the fixed frame 33.
is supported via a bearing 36.

A torsion spring 50 is provided wound around the end of the output shaft 42 inside the rotary housing 46.
One end is locked in a groove of the output shaft 42, and the other end is fitted and locked in a notch 46a of the rotary housing 4G.

Therefore, the rotation of the rotary housing 46 is caused by the torsion spring 50.
is transmitted to the output shaft 42 via.

Further, a potentiometer 51 is incorporated inside the rotary housing 41 fixed to the other surface of the input gear 41, and a potentiometer shaft 52 of the potentiometer 51 protrudes into the central circular hole of the input gear 41 and is coaxial with the output shaft 42. The distal end flat plate portion 52a thereof is fitted into a groove provided at the end of the output shaft 42.

Therefore, the potentiometer 51 can detect the relative displacement between the rotating part 45 and the output shaft 42 due to the deformation of the torsion spring 50.

The opening on the side opposite to the input gear 41 of the rotating housing 41 is covered with a disc 54 with a buffer material 53 interposed therebetween.
Li shock material 539 rotating housing 47. Long screws 56 pass through the input gear 41° rotation housing 46 at several predetermined locations and are screwed together.

A rotary shaft 55 is integrally erected at the center of the disc 54, and the rotary shaft 55 is located inside the fixed housing 43 and supported via the bearing 44.

Inside the fixed housing 43, two terminal rings 58 and 59 are arranged around the circumferential surface of the rotating shaft 55 with an insulating material 57 interposed therebetween.
Two of the wooden electric wires 60, 61, and 62 pass through small holes provided in the disk 54 and are fixed at one end to the terminal rings 58 and 59, respectively, and the remaining ground wire 1a62 is fixed to the disk 54 itself. ing.

Three brushes 63, 64, 65, which are fixed to the fixed housing 43 and protrude inside the fixed housing 43, are in contact with the terminal ring 58, 59 and the rotating shaft 55 itself. Output harnesses 66 each extend from .64 and 65.

Since the torque detector 40 has the above structure,
When the rotation of the gear 35 due to the drive of the DC motor 30 is transmitted to the input gear 41, the rotating part 45 rotates together, the same rotation is transmitted to the output shaft 42 via the torsion spring 50, and then the rotation of the output shaft 42 is As described above, the return roller 3 is rotated via the flexible joint 379 rotating shaft 17.

When the DC motor 30 is rotationally driven with a load applied to the return roller 3, the torsion spring 50 is compressed by the output torque of the DC motor 30, and the rotation part 45 and the output shaft 42 are A rotation angle displacement occurs, and the potentiometer shaft 52 is rotated relative to the potentiometer 51 body, and the rotation angle is used as an electric signal to connect the electric wire 60.61.6.
2. Terminal ring 58.59. It can be output from the output harness 6G via brushes 63, 64, 65.

Therefore, the output torque of the DC motor 30 for a certain load on the return roller 3 can be detected.

FIG. 4 shows a control circuit for the DC motor 30 based on the torque detection signal from the torque detector 40.

[E■Transistor 70. Resistance 71. A constant reference voltage formed by a series connection of Zener diodes 12 is applied to the torque detector 40, the output of which is applied to the operational amplifier 7.
It is input to the inverting input terminal of No. 3.

On the other hand, FET transistor 14. Resistance 75. A reference voltage formed by series connection of Zener diodes 76 is applied to a variable resistor 77 for torque adjustment, and its output voltage is inputted to the non-inverting input terminal of the operational amplifier 73.

The output terminal of the operational amplifier 73 is connected to the base terminal of the transistor 19 via a resistor 78.

The base terminal of the transistor 19 is connected to the power supply via the resistor 80, and the collector terminal is directly connected to the power supply.
The emitter terminal is connected to the input terminal of the DC motor 30.

Since the motor control circuit is configured as described above, the operational amplifier 73 compares the reference voltage for comparison adjusted by the variable resistor 17 and the detected voltage of the torque detector 40, and the detected voltage is lower than the reference voltage. If low, i.e. DC motor 3
When the output torque of 0 is small, the operational amplifier 13 increases the base potential of the transistor 79, increases the load Ti current of the DC motor 30, and operates to increase the output torque. is large, that is, when the output torque of the DC motor 30 is large, the load current to the DC motor 30 is reduced to reduce the output torque, and the output torque of the DC motor 30 is always controlled to be constant.

In this way, since the output torque of the DC motor 30 is always controlled to be constant, IIJtlD is performed so that the above-mentioned conditional expressions (1) and (2) are always satisfied.

The sheet feeding device according to the present embodiment has the structure and control system as described above. Looking at its operating procedure, first, as shown in FIG.
The pickup roller 1 is placed on top by its own weight, and the pickup roller 1. The feed roller 2 is driven to rotate clockwise, and the return roller 3 is driven by the DC motor 30 at the time g.
Receives torque in one turn.

The return row 53 is pressed against the upper feed roller 2 by a constant pressing force N via the swinging member 18 due to the spring force of the tension spring 20, and when the sheet P is not sandwiched, the distance between the two is m. Since the coefficient of friction is large, the return roller 3 is rotated counterclockwise in the a1 direction as the feed roller 2 rotates against the output torque T of the DC motor 30.

When the sheet P is sandwiched between the one-sheet feed roller 2 and the return roller 3 due to the rotation of the pickup roller 1, an output torque T1 that satisfies the above formula (1). : Since it is set, the return roller 3 still applies the output torque T.
The sheet P is rotated counterclockwise against the pressure and discharged onto the guide plate 7.

However, if two sheets P are accidentally caught between the feed roller 2 and the return roller 3, the return roller 3 will move the lower sheet P because the frictional resistance between the upper and lower sheets P is small.
rotates in the direction in which it returns, that is, in the direction in which torque T is applied, and the output torque T decreases, so the torque detector 40 detects this change in output torque and controls the output torque T to be constant, thereby maintaining a constant output torque. (2) above while maintaining T
By satisfying the formula, the lower sheet P can be smoothly pushed back and double feeding can be avoided.

As described above, by maintaining the output torque constant, double feeding is prevented, and smooth sheet feeding becomes possible.

Since the output torque T is controlled by controlling the load current of the motor, there is no change over time unlike with a torque limiter, and stable sheet feeding is possible at all times, greatly extending the service life.

Further, by combining the torsion spring 50 and the potentiometer 51, the mechanism can be simplified and reliability can be improved, and the device can be made smaller and lower in cost.

Next, a modified example of the torque detector is shown in FIG.

A rotating part 96 and an output shaft 97 of the torque detector 95 are supported on a fixed frame 90, 91 via bearings 92, 93, respectively, and the output shaft 91 is connected to a rotating inner ring of the bearing 93 via an E ring 94. Since it is fixed, axial movement is restricted and only rotation is possible.

The rotating part 96 has an input gear 99 fitted to the outer periphery of a cylindrical rotating housing 98 having a bottom portion 98a, and a disc 10 integrated with a rotating shaft 100 in an opening of the rotating housing 98.
1 is fixed to cover the lid.

A rotating shaft 100 is rotatably supported by the bearing 92 to allow movement in the axial direction.

The output shaft 97 has a male thread formed at a predetermined location,
The end of the output shaft 91 is screwed into a female thread formed on the bottom 98a of the rotary housing 98.
A screw spring 102 is wound around the same end, one end of which is locked in a notch in an output shaft 97, and the other end is locked in a notch in a rotary housing 98.

Further, the fixed frame 90 has a potentiometer 103.
is fixed at a predetermined position, and the rotating actuator 104 is biased by a spring 105 so that its end is always in contact with the disk 101.

An output harness 106 extends from the potentiometer 103.

Since the present torque detector 95 has the above-described structure, when the gear 107 that meshes with the input gear 99 rotates due to the drive of a motor (not shown), the rotating housing 98 rotates together with the input gear 99, and the rotating housing 98 rotates together with the input gear 99. The rotation 98 rotates the output shaft 97 via the torsion spring 102.

At this time, due to the load applied to the output shaft 91, the torsion spring 1
02 is deformed, and a relative rotational angular displacement occurs between the rotational housing 98 and the output shaft 97. move in the axial direction.

This axial movement of the rotary housing 98 operates the 7 actuator 104 of the potentiometer 103, so that the relative displacement between the rotary housing 98 and the output shaft 91, that is, the output torque of the motor, is controlled by the potentiometer.
103.

If the load current of the motor is controlled by the control circuit of the above embodiment based on this detection signal, stable sheet feeding can be achieved by keeping the output torque constant.

Next, another example of the torque detector will be explained based on FIGS. 6 to 8.

An input shaft 112 and an output shaft 113 are rotatably supported at their ends by bearings 111 on both side walls of the box 110, respectively.

Drive from a motor is transmitted to the input shaft 112 via gears, etc., and a return roller is fitted to the output shaft 113.

The input shaft 112 and the output shaft 113 are coaxial, and a slit disk 114 is provided at the end thereof. 115 facing each other vA
It is worn.

Further, a torsion shaft 116 made of a small diameter cylindrical rigid material is located between the input shaft 112 and the output shaft 113 with its center axes being equal, and its both ends are fixed to the input shaft 112 and the output shaft 113, respectively. The two are connected.

Therefore, the rotation of the input shaft 112 is transmitted to the output shaft 113 via the torsion shaft 116, but the torsion shaft 11G is twisted according to the load on the output shaft 113, and the relative rotation angle of the opposing discs 114 and 115 is Displacement changes.

Both disks 114. Reference numeral 115 has the same shape, and fan-shaped slit holes 114a and 115a are formed at equal pitches on the outer periphery, so that no load is applied to the output shaft 113 and the disc 114 and 1
When there is no relative displacement in 15, both slit holes 114
a and 115a completely overlap.

FIG. 7 shows both discs 114. 115 viewed from the direction of the arrow in FIG. 6, and FIG. 7(a) shows the output shaft 11.
Slit holes 1 in disks 114 and 115 without applying any load to 3.
14a and 115a are completely overlapped, and FIG. 7(b) shows a state in which a slight load is applied to the output shaft 113 and the disc 114
and 115, that is, the torsion shaft 116 is twisted, and the disc 115 on the output shaft 113 side is delayed from the disc 114 on the input shaft 112 side, and both slit holes 1
The area of the overlapping portion of 14a and 115a (diagonal $1 portion) is reduced.

FIG. 7(C) shows the state when a load is applied to the output shaft 113, and the area of the overlapping portion of both slit holes 114a and 115a is further reduced.

In order to detect the state of this overlapping portion, a photo interrupter 117. 118 is fixed with a set screw 119, and each photo interrupter 11
7. 118 is a slit disk 114. Light emitters and light receivers are arranged so as to sandwich the outer periphery of the light emitting device 115, respectively.

Therefore, each photointerrupter 117. 118 indicates each disk 114. 115 slit hole 114a.

115a can be detected.

Each photo interrupter 117. 118 through a connector 120 to an output harness 121. 122 extends and both are connected to an input terminal of an AND circuit (not shown).

FIG. 8 shows the waveform of the detection signal.

FIG. 8(a) shows a case where there is no load on the output shaft 113 (the seventh
Figure (a)), (b) is when a slight load is applied (Figure 7 (b)), and (C) is when a further load is applied (Figure 7 (C)). It shows the waveform.

When no load is applied to the output shaft 113 (Fig. 8 (a))
is the output signal of photointerrupter 111 on the input side■
and the output signal (2) of the photointerrupter 118 on the output side are in phase, and the output signal (2) of the AND circuit also has the same waveform.

When a slight load is applied to the output shaft 113 (Fig. 8(b)),
The output side output signal ■ is delayed more than the input side output signal ■, and the high level time of the AND circuit output signal ■ is slightly shorter.

Furthermore, when a load is applied to the output shaft 113 (Fig. 8 (C))
, the output side output signal (2) is delayed, and therefore the high level time of the output signal of the AND circuit is roughly shortened.

The motor is driven and controlled based on the output signal ■ of the AND circuit, and if the high level time of the output signal ■ is taken as the motor on time, when the load applied to the output shaft 113 is small, the motor on time is lengthened, When the load is large, the motor output torque can be maintained constant by shortening the motor on time.

In this example as well, the torque detector has a simple structure, is small in size, has high reliability, and has a long life.

Next, FIG. 9 shows a return roller drive mechanism equipped with yet another torque detection 1a41.

A box 130 is swingably supported by a support shaft 131, and springs 132 are interposed at four locations between the bottom plate of the box 130 and the fixed portion at the front, rear, left, and right.

A motor 133 is fitted into the inside of the box 130, and the drive shaft of the motor 133 has the same central axis as the support shaft 131, and a gear 134 is fitted to the end of the motor 133.

The return roller 135 is rotatably supported by the rotating shaft 13.
A gear 137 is fitted to the rotating shaft 136, and the gear 137 meshes with the gear 134.

On the other hand, a potentiometer 138 is attached to a fixed part near the box 13G, and its actuator 13
9 is pivotally supported at its base end and protrudes so as to be able to swing up and down,
The tip thereof is biased so as to be in constant contact with the bottom plate of the box 130.

When the motor 133 is driven and the gear 134 rotates, the return roller 135 rotates via the gear 131.

At this time, the box 130 attempts to rotate in the opposite direction about the support shaft 131 against the spring 132 due to the reaction of the rotation of the gear 134.

This reaction is large because the load applied to the return roller 135 is large, and the rotation angle of the box 130 due to this reaction is determined by the movement of the actuator 139.
38 can be detected.

Based on the detection signal of the potentiometer 138, the motor 91
By controlling the current at 33, the output torque T can be maintained constant, and the sheet can be fed smoothly.

In this example as well, the output torque can be controlled at a constant level using the ff1lll mechanism, and there is almost no change over time, resulting in a long life.

The present invention detects the output torque of the motor and controls the output torque to be maintained at a constant predetermined value based on the detected information, so that double feeding is performed while always satisfying the required conditions. This allows only one sheet to be sent out smoothly.

Since there is no change over time such as wear like a torque limiter, there is no need to regularly replace parts, and the service life is greatly extended.

In addition, the motor drive is transmitted to the return roller via the spring,
By detecting the change in the spring with a potentiometer to detect the output torque of the motor, the mechanism can be simplified, downsized, and lowered in cost, and reliability can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of a sheet feeding device of a copying machine according to an embodiment of the present invention, FIG. 2 is a perspective view showing a drive mechanism of the same sheet feeding device, and FIG. Fig. 4 is a control system circuit diagram of the same sheet feeding device, Fig. 5 is an internal structure diagram of another torque detector, and Fig. 6 is an internal structure of another torque detector. 7 is a diagram showing the overlapping state of the slit disks of the same torque detector, FIG. 8 is a diagram showing the state of the detection signal of the same torque detector, and FIG. 9 is a diagram showing the state of the detection signal of the same torque detector. FIG. 10 is a schematic explanatory diagram of the sheet feeding device, and FIG. 11 illustrates the state when one sheet is caught between the feeding roller and the return roller. FIG. 12 is an explanatory diagram for explaining the situation when two sheets are sandwiched between the feed roller and the return roller. P...Sheet, 1...Pickup roller, 2...Feed roller, 3
... Return roller, 4... Paper feed tray, 5... Bottom plate, 6... Wire, 7... Guide plate, 10... Fixed frame, 11... Rotating shaft, 12...
・Winging plate, 13... Rotating shaft, 14.15.16...
Gear, 17... Rotating shaft, 18... Swinging member, 18a
...Arm part, 18b...Connection part, 19...Spindle, 2
0...Tension spring, 21...Fixed frame, 2
1a... Side body, 21b... Projection part, 30... DC motor, 30a... Drive shaft, 31... Flexible joint, 32... Gear shaft, 33... Fixed frame , 34... Bearing, 35... Gear, 3G... Bearing, 37... Flexible joint, 40... Torque detector, 41... Input gear, 42...
... Output shaft, 43... Fixed housing, 44... Bearing, 45... Rotating part, 46° 47... Rotating housing, 48... Bearing, 50... Torsion spring, 51...
・Potentiometer, 52...Potentiometer shaft,
53... W member, 54... Disc, 55... Rotating shaft, 56... Screw, 57... Insulating material, 58.59...
・Terminal ring, 60.61.62...Electric wire, 63.6
4.65...Brush, 66...Output harness, 10...EE■transistor, 11...Resistor, 72
...Zener diode, 73...Operation amplifier, 7
4...FE■Transistor, 75...Resistor, 76...
... Zener diode, 77 ... Variable resistor, 78
... Resistor, 79... Transistor, 80... Resistor, 90, 91... Fixed frame, 92.93... Bearing, 94... E-ring, 95... Torque detector, 96
...Rotating part, 97...Output shaft, 98...Rotating housing, 99...Input gear, 100...Rotating shaft, 1
01... Disk, 102... Torsion spring, 103...
・Potentiometer, 104...actuator, 1
05...Spring, 10G...Output harness, 1
01... Gear, 110... Box, 111... Bearing, 112... Input shaft, 113... Output shaft, 114. 115... Slit disk, 116... Torsion shaft, 117. 118
...Photo interrupter, 119...Set screw, 1
20... connector, 121. 122... Output harness, 130... Box, 131... Support shaft, 132... Spring, 133... [-ta, 134... Gear, 1
35... Return roller, 136... Rotating shaft, 137...
...Gear, 138...Potentiometer, 139...
・Actuator.

Claims (1)

[Claims] 1. A feed roller that is rotationally driven in the sheet feeding direction, a return roller that is pressed against the feed roller, a motor that applies torque to the return roller in the sheet return direction, and an output of the motor. 1. A sheet feeding device for an image forming apparatus, comprising: a torque detection means for detecting torque; and a control means for constant control of output torque of the motor based on information detected by the torque detection means. 2. The image according to claim 1, wherein the torque detection means is a mechanism for transmitting the drive of the motor to the return roller via a spring and detects a change in the spring using a potentiometer. Sheet feeding device of forming equipment.