Sheet feeding or delivering – Feeding – By means to convey sheet
Reexamination Certificate
1999-01-27
2001-10-30
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Feeding
By means to convey sheet
C271S003150, C271S003170, C271S229000
Reexamination Certificate
active
06308951
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The invention claims priority of German Patent Application No. 198 04 929.3 filed Feb. 07, 1998, titled “Device For Detecting A Sheet Stack Height In A Tray”. by Franz Allmendinger, et al.
FIELD OF THE INVENTION
The invention relates generally to a device for detecting the stack height of sheets stacked in an input and/or output tray of an apparatus such as a printer or copier.
BACKGROUND OF THE INVENTION
Devices for detecting stack height of sheets are known in the art. In EP-0 768 263-A1, a conventional device for detecting stack height is disclosed. According to this prior art development, means is provided for detecting a stack height in at least one collecting tray of an output unit of a printer. More particularly, a feeler is provided in the form of a pivotable feeler bracket movable cyclically against the sheet stack into a sensing position. At some position above the sheet stack and in the stacking direction, a sensor in the form of an opto-electronic sensor senses the position of the feeler and detects the sheet stack height. The feeler bracket in the aforementioned prior art development has at a first end a feeler/pressure finger pivoted by means of a microprocessor-controlled reciprocating magnet about its center rotation axis. The reciprocating magnet is joined via a spring element at its reciprocating armature to a second end of the feeler bracket located opposite the first, at which a switching tab for actuating the sensor is also arranged. The feeler bracket, sensor, and reciprocating magnet are arranged outside the collecting tray and in front of the end-surface wall of the collecting tray, i.e. the front alignment edge for the paper sheets delivered into the collecting tray. With the feeler bracket in an initial position, the feeler finger is located above and out of engagement with the front region of the sheet stack, and the switching tab is outside the sensing region of the sensor. During the sensing cycle, the feeler bracket pivots through a slot in the end-surface wall into the collecting tray and, with the feeler finger, onto the sheet stack, whereby the switching tab pivots in the direction of the sensor. Not until the maximum permissible stack height is reached is the sensor actuated or covered by means of the switching tab, and a signal is sent to the control unit to stop sheet in-feed. Alternative embodiments have sensor means (multiple sensors) or switching tabs (with multiple slots) for detecting intermediate values of the sheet stack height. To detect a first sheet in the collecting tray, a further sensor is arranged in its bottom or deposition surface.
A major shortcoming of the above and other similar existing sheet stack height detecting devices is that the reciprocating magnet generates severe vibration and noise. Further, such devices require complex sensor means to detect exact intermediate values of the sheet stack height and to detect the first sheet in the collecting tray. A further shortcoming of existing developments is that the means for detecting the stack height are located in the region of a possible transport path for the completed sheet stack, or in the removal/input region of the collecting tray.
Therefore, a need persists in the art for a device for detecting stack height of sheets stacked in an input and/or output tray of an apparatus that is compact, and simple to construct, cost effective to manufacture and relatively simple to operate.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide a device for detecting the stack height of stacked sheets that has a compact configuration.
Another object of the invention is to provide such a device that has freely selectable measurement steps and high measurement accuracy at each stack height.
Yet another object of the invention is to provide a device that operates essentially noise-free and vibration-free.
Still another object of the invention is to provide a device that operates in an automated environment without interrupting sheet in-feed or removal.
It is a feature of the invention to provide a controllable stepping motor in which a feeler is movable from a predetermined initial position toward the sheet stack and then into a sensing position. The stack height of the sheets can then be determined on the basis of the number of motor steps detected from the initial position until the sensing position of the feeler is recognizcd.
To achieve these and other objects of the invention, there is provided a device for detecting the stack height of sheets stacked in an input and/or output tray of an apparatus. The device comprises a feeler cyclically controlled and driven by means of a drive unit and a control unit toward the sheet stack in the stacking direction into a sensing position. A sensor detects the sheet stack height and recognizes the sensing position of the feeler. Further, the device has a controllable stepping motor which enables the feeler to move from a predetermined initial position (y, z′) toward the sheet stack and into the sensing position (y′, z). In this way, the stack height can be determined on the basis of the number of motor steps detected from the initial position until the sensing position of the feeler is recognized.
There are numerous advantages of the present invention over prior art developments. In one respect, the stepping motor, or the stepping motor in conjunction with a control can having a cam plate, advantageously provides a step spacing which is smaller than a smallest sheet thickness of the sheet types that can be used. In another respect, the sensing cycle of the feeler is either automatically or manually adjustable both as a function of a number of sheets delivered to or discharged from the collecting tray and as a function of a sheet thickness of a sheet type being used. Further, it is an advantage that the feeler is movable by means of the stepping motor or the stepping motor in conjunction with the cam plate. The feeler moves with a velocity profile such that the linear velocity of the feeler is diminished in the region before the sensing position, the initial position, and a removal/input position.
Moreover, it is an advantage of the present invention that output signals from sensors positioned about the stack for determining stack height can be detected by a control unit comprising a microprocessor, a counting device and a calculation means.
Furthermore, another advantage of the present invention is that the feeler has a feeler finger arranged on a support that can be moved in the stacking direction by the stepping motor. The feeler finger is arranged on the support so as to be movable back and forth in the movement direction of the support against a spring element, and can be moved and pressed with its feeler tip against the sheet stack.
In addition, advantageously, the feeler, the sensor, and the drive unit with the stepping motor and the radial cam are arranged above the sheet stack and tray.
Moreover, advantageously, means for aligning a respective topmost sheet of the sheet stack and/or for temporarily retaining delivered sheets are displaceable, as a function of a determined sheet stack height, into their predetermined working position with respect to the sheet stack.
REFERENCES:
patent: 4702470 (1987-10-01), Ishii
patent: 5620174 (1997-04-01), Taniguro et al.
patent: 6068254 (2000-05-01), Olexy
patent: 6247695 (2001-01-01), Linder et al.
patent: 0 768 263 A1 (1997-04-01), None
Allmendinger Franz
Buck Joachim
Graeber Jochen H.
Koenig Volker H.
Michels Heinz
Beauchaine Mark J.
Nexpress Solutions LLC
Walsh Donald P.
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