JPH026014Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a nip release device for an automatic document feeder such as a printer or a copying machine.

Conventional technology As a conventional automatic document feeder, for example,
The document placed on the document tray 1 passes through a weight counter 2, is sandwiched between a separate roller 3 and a feed roller 4, and is transferred to a drive roller by the operation of a drive motor provided on a side frame (not shown). 5 and an idler roller 6, it is sent along a fish plate 7 to a printer or a copying machine (not shown).

The pressure of the rollers during document feeding is adjusted by rotating pressure adjusting screws 8 and 9 at two locations, the feed roller 4 and the drive roller 5.
In this case, if the roll pressure is inappropriate, uneven in the width direction, or the operator is clumsy when inserting the document, the document may fold between the rollers or become jammed between the rollers. Situations often occur. In such cases, it is necessary to temporarily release the nip (release the state where the original is caught between the rollers) in order to remove the jammed or folded original from the automatic document feeder. . Therefore, in the conventional automatic document feeder, the cam 10 provided inside or outside the main body 22 is rotated as shown in FIG.
and 12 are moved to remove the pressure applied to the feed roller 4 and drive roller 5, thereby releasing the nip. Note that the rotational axes indicated by p, q, and r are shown to be coaxial in FIGS. 2 and 3.

Problems to be Solved by the Invention However, in such a nip release method, it is necessary to process the cam 10 into an accurate shape and size, and the arms 11 and 12 of the cam 10 are
Surface treatment must be performed on the contact surface to prevent wear, which increases costs.

An object of the present invention is to solve the above problems and provide a nip release means that can be manufactured and assembled at low cost.

Means and Effects for Solving the Problems The automatic document feeder of the present invention is an automatic document feeder that holds a document between a pair of rollers and feeds the document by the rotation of the rollers. a first bracket that is provided and rotatably supports one roller of the pair of rollers; a wire that has one end attached to the first bracket; and one roller that is pressed against the other roller. a spring acting on the wire in such a manner that
a second bracket that is displaceable with respect to the apparatus main body and has a free end fixed to the wire; and a second bracket that is displaced in a direction that causes the one roller to move away from the other roller. and a nip force release means for releasing the biasing force of the spring acting on the wire.

According to the above configuration, the nip force releasing means displaces the second bracket to release the spring biasing force acting on the wire, and temporarily separates one roller from the other roller. The contact pressure between the pair of rollers that are in contact with each other during normal operation of the device can be temporarily released, that is, the nip can be temporarily released. This eliminates the need for an expensive cam mechanism.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in Fig. 1, a bracket 13 (first bracket) supports the feed roller 4 in a freely rotatable manner.
is attached to the document feeder main body 22 so as to be freely rotatable about a fulcrum a, and one end of a wire 14 is connected to one end 13a thereof. The same goes for the idle roller 6, and a bracket 15 (first bracket) that freely rotatably supports the idle roller 6 is mounted so as to be rotatable about a fulcrum b.
One end of the wire 16 is connected to b. These wires 14 and 16 go around the outer periphery of the fulcrum shaft 17 and along the bottom of the document feeder main body 22.
The other ends of the wires 14 and 16 are connected to the coil spring 20, and the wires 14 and 16 are connected to the bracket 18 at their intermediate portions or near the connection points with the coil spring 20.
(second bracket). The bracket 18 is movable relative to the main body 22 about the fulcrum c (rotatable or rockable in this embodiment).
Wires 14 and 16 are respectively fixed by wire fixing screws 19 to the wire connecting portions which are attached to the wire and serve as free ends thereof. In the vicinity of the wire connection portion of the bracket 18 or in the wires 14 and 16,
One end 20a of the coil spring 20 is fixed, and the other end 20a is fixed.
0b is attached to the main body 22 at the rear of the bracket 18 via a wire tension adjustment screw 20b.

In the above configuration, the contact pressure when the feed roller 4 and the idler roller 6 are pressed against the separate roller 3 and the drive roller 5 is set to an optimum value by rotating the wire tension adjustment screw 20b. If an abnormality occurs such as the document being folded between the rollers or jammed between the rollers, a motor shaft 21 having a semicircular cross section, which is directly connected to a pulse motor (not shown) in this embodiment, is rotated. As a result, the bracket 18 rotates in the direction A around the rotation axis c, the tension of the wires 14 and 16 weakens, and the feed roller 4 and idler roller 6 are displaced in the directions B and C, respectively, and the separate roller 3 and drive roller 5, and the pressure applied to the document is released. In this case, the motor shaft 21 does not necessarily have to have a semicircular cross section, but may have any shape as long as it allows the bracket 18 to rotate by the amount necessary to weaken the wire tension.

Effects of the invention The automatic document feeder of this invention can release the nip by applying pressure to the document between the rollers using the tension of the wire connected to the coil spring and temporarily releasing the wire tension. This has the advantage that the mechanism can be omitted and the component parts can be manufactured and assembled at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention, FIG. 2 is a schematic sectional view showing a conventional example, and FIG. 3 is a schematic side view showing a conventional example. 1: Original tray, 4: Feed roller, 6: Idler roller, 13, 15: Bracket, 14,
16: wire, 17: fulcrum shaft, 18: bracket, 20: coil spring, 21: motor shaft, 22:
Document feeder main body, a, b, c: fulcrum

Claims (1)

[Scope of utility model registration request] In an automatic document feeder that holds a document between a pair of rollers and feeds the document by rotation of the rollers, a second roller is rotatably provided with respect to the main body of the device and rotatably supports one of the rollers of the pair of rollers. a wire having one end attached to the first bracket; a spring acting on the wire so that the one roller presses against the other roller; a second bracket provided with a free end fixed to the wire; and a spring biasing force acting on the wire by displacing the second bracket in a direction to move the one roller away from the other roller. An automatic document feeder comprising a nip force release means for releasing the nip force.