DE2154223C3 - Separation device, in particular for electrostatic copiers - Google Patents

Description

sin α>

1 / M _G cos α _ M

r _G

_ MA

45

is enough, where

Mc is the moment of frictional resistance of the sliding roller (5),

Ma is the moment of frictional resistance of the feed roller (3),

Pa is the pressure of the feed roller (3),

rc is the radius of the roller (5) and

/ 7. means the distance between the roller axes (4.6).

4. Separation device according to one of the preceding claims, characterized in that that the circumference of the feed roller (3) has two sliding rollers (5,

7) are arranged, with the front roller (7) in the direction of rotation (A) of the feed roller (3) being heavy and the rear roller (5) easily rotatable.

5. Isolation device according to one of the preceding claims, characterized in that that the recess (3a) has a flattening of the feed roller (3) running in the direction of a secant The invention relates to a separating device, in particular for electrostatic copiers, at which in each case a copy carrier by means of a pressure force applied to the top sheet of a Stack resting on top of a stacking table bearing the stack of sheets movably mounted, intermittently An elastic cover with a high coefficient of friction, driven by a one-way clutch having feed roller while overcoming the resistance of stack-side separating elements on the device side Transport rollers are supplied, which further transport the copy medium through the device take over.

In the known devices of this type, the feed roller is means during the first transport phase driven by a freewheel. After the front edge of the copy carrier has been caught by the transport rollers, this takes the feed roller in the freewheeling direction until its rear edge is the contact point of the feed roller Happened on the stack as a result of the deformation of the elastic roller cover near the point of support occurs shortly before the feeder roller comes into contact with the still moving roller the next sheet to be removed, which takes it with you a little bit. It will be sent to the Separating elements, e.g. B. the well-known corner stops, compressed and usually suffers a permanent deformation, which is detrimental to the trouble-free transport of the sheet through the device

The invention is now based on the object of creating a device through which on simple Way is prevented with certainty that in a copier of the type mentioned in the End phase of the sheet separation process through the sheet following the sheet to be separated, the feed roller is taken.

According to the invention this is achieved in that the feed roller at at least one point of its circumference has a recess and that in the region of the recess at least one with the circumference of the Feed roller is arranged in such a way that a simultaneous sliding element is substantially aligned Contact of the sliding element and the edge of the lying in the conveying direction in front of the sliding element Recess-forming part of the elastic cover with the stack surface is possible, in this Position a standing level for the investor role is formed.

This sliding element according to the invention, which is preferably a sliding roller, prevents in the In the last transport phase, the elastic feed roller also rotates and, since there is no elastic cover itself has, an entrainment of the next, lying on the stack sheet.

In a further embodiment of the invention, the roller is arranged and dimensioned so that the Line connecting its axis with the axis of the feed roller in the one specified by the contact plane Rest position of the feed roller with the direction of the pressure force acting on the roller axis Angle includes which of the conditions

sin α>:

is enough, where

1 / M _G cos a _ ΜΛ
Pa \ 'β r _L )

Mc is the frictional resistance torque of the sliding roller,

M is the moment of frictional resistance of the contact

^A role

ρ ι the pressure force of the feed roller, _rr the radius of the sliding roller and

means the distance between the roller axes.

IO

Pem co-rotating moment of the Gloitrolle is then countered by η caused by the pressure force, turning backward on moment, so that even a smooth-running feed roller definitely comes to a standstill

According to a further advantageous embodiment of the invention, the circumference of the feed roller is arranged on the circumference of the feed roller, which is offset from one another by the angle 2 α, the front roller being difficult to rotate and the rear roller being easy to rotate in the direction of rotation of the feed roller. Due to its relatively high frictional resistance, the fixed sliding roller takes over the rotation of the feed roller up to the position in which both rollers are in contact with the copy carrier and the perpendicular perpendicular to the connecting line of the roller axes coincides with the direction of application of the pressure force. A further rotation of the anchor roller is prevented by the selection of the angle χ between the perpendicular or force and the second sliding roller corresponding to the previous requirements. With a suitable choice of this angle, there is only a substantial reduction in the contact pressure of the fixed sliding roller and thus its frictional resistance exerted on the copy carrier. Since both rollers are in contact, after the intermittent drive of the feed roller is restarted, there is no significant idle stroke until the elastic cover abuts or the next sheet is conveyed.

Finally, the recess is a flattening of the feed roller running in the direction of a secant, whereby the angle χ generating the backward turning moment can be selected relatively large without contact between the copy carrier and the elastic cover of the feed roller occurring between the contact points of the sliding rollers.

Some embodiments of the invention are shown, for example, in the drawing. It shows

1 shows the pulling through of a copy carrier under an elastic feed roller of a known type,

2 shows a feed roller equipped with an additional sliding roller,
Fig. 3 one equipped with two castors

Investor role and

4 shows a certain rotational position of the feed roller

⁸⁶ In ^{FIG. 8} , an elastic feed roller 3 rests on the top sheet of a stack 1 under the action of a pressure force P _A. The pressure force Pa comes about in a known manner by weight or spring forces acting on the feed roller 3 or on the stack 1. The figure shows the moment at which the rear edge 2a of the copy carrier 2 passes through the contact point of the elastic roller 3 on the stack 1. As a result of the elastic deformation of the feed roller 3, the elastic coating of this roller is not only in contact with the sheet 2 that has been pulled off but also with the subsequent sheet of the stack. This sheet is therefore shifted at least a little bit in the direction of the arrow C during the rest of the rotation of the feed roller 3 in the direction of the arrow A.

According to FIG. 2, the elastic cover of the feed roller 3 is provided with a recess 3a extending in the direction of a secant. On the side wall of the feed roller 3, an axle 4 is attached, aui which one, for. B. made of polished steel roller 5 is mounted. If the top copy carrier 2 is pulled off in the direction of arrow C under such a feed roller, the feed roller 3 is carried along in the direction of arrow A until both the edge K delimiting the recess 3a and the sliding roller 5 rest against the copy carrier 2 in the manner shown in the figure . For further rotation of the feed roller 3, the edge K would have to lift off the copy carrier 2, which can only take place if the torque transmitted by the sliding roller 5 is sufficient for this. The following balance of power exists here:

The torque acting on the feed roller 3 in the direction of arrow A results from the bearing force P _u acting on the lever arm r _L ■ cos α, the maximum amount of which depends on the frictional torque Mc of the sliding roller 5 and its radius r _c. It applies

P, =

M ₁

(D

This results in the maximum forward rotating torque Mv-

M _v =

cos a

(2)

The pressure force Pa acting on the lever arm r _L - sin α comes into consideration as the backward turning moment Mr. It is

M _R = P _A '· r _L - sin «.

(3)

In addition, the friction torque M _{A of} the feed roller itself must be overcome. The condition for the standstill of the feed role is accordingly

or.
sin

- ρχ ■ r _L ■ sin a

" _Nua 1 / Mccosa _ΜΛ ~ Pa \ r _G r _L J

(4)

(5)

By appropriate choice of the angle depending on rt and rc , it is therefore in the hand to prevent further rotation of the feed roller 3 with certainty. The copy carrier 2 then only moves the sliding roller 5, which in turn cannot take the next copy carrier with it because of its low deformability and the relatively low coefficient of friction of its surface. It is also possible to choose the angle λ only so large that, although it prevents co-rotation, the contact pressure of the edge K is already considerably reduced. In this way, the abrasion of this edge can be kept small.

In order to completely prevent abrasion of the edge K , according to FIG. 3 attached to the side wall of the feed roller two axles 4 and 8, on which two rollers 5 and 7 are mounted. The sliding roller 5 can be rotated easily, while the sliding roller 7 is heavy

is rotatably or non-rotatably connected to its axis 8. The center lines of the axes 4, 6 and 8 together form the angle 2a, which is halved by the direction of the pressure force P _{A when the two rollers are placed on the copy carrier 2.}

The stiffness of the roller 7 is necessary because otherwise the feed roller 3 through the copy carrier 2 only up to the point shown in FIG. 4 position could be taken, in which the edge K still grinds on the copy carrier 2. In addition, a considerable idle stroke would first have to be carried out from this position when the next transport stroke of the feed roller 3 begins in the direction of arrow A until the edge K ' comes into contact with the copy carrier 2 and takes it with it.

As the feed roller 3 continues to rotate from the position shown in FIG. The position shown in FIG. 3 by the copy carrier 2 moved in the direction of arrow C , in which the sliding roller 7 would have to lift off the copy carrier 2, results, as can be seen from the figure, with respect to FIG. 2 calculated torques. This means that a forward-turning moment is created by the attack of the bearing force Pl

ίο on the lever arm r *. Cos α and a reversing moment due to the application of the pressure force Pa on the lever arm Π sin α where the difference between these two moments seeks to overcome the frictional moment Ma,

For this purpose 2 sheets of drawings

Claims (3)

Patent claims: 1. Separation device, in particular for electrostatic copiers, in which one copy carrier in each case is an elastic coating with a high coefficient of friction, which rests on the top sheet of a stack under the action of a pressure force, is movably mounted relative to a stacking table carrying the sheet mirror and is intermittently driven by means of an overrunning clutch having feed roller is supplied with overcoming the resistance of stack-side separating elements device-side transport rollers which take over the further transport of the copy carrier through the device, characterized in that the feed roller (3) has a recess on at least one part of its circumference and that in the region of the recess at least one with the circumference of the feed roller (3) substantially aligned sliding element (5) is arranged in such a way that a simultaneous contact of the sliding element (5) and the in the conveying direction in front of the sliding element (5) l The lying edge (K) of the recess-forming part of the elastic cover with the stacking surface is possible, with a contact plane for the feed roller (3) being formed in this position. 2. Isolation device according to claim 1, characterized in that the sliding element is a Roller (5) is 3. Isolation device according to claim 2, characterized by such an arrangement and Dimensioning of the roller (5) that the line connecting its axis (4) with the axis (6) of the Feed roller (3) in the rest position of the feed roller (3) with the predetermined by the contact plane The direction of the pressure force acting on the roller axis (6) includes an angle λ which the condition