Sheet-material associating – Associating or disassociating – Sheet associating
Reexamination Certificate
2003-01-11
2003-07-22
Mackey, Patrick (Department: 3651)
Sheet-material associating
Associating or disassociating
Sheet associating
C270S058080, C399S410000, C227S002000, C227S005000
Reexamination Certificate
active
06595509
ABSTRACT:
FIELD OF THE INVENTION
The invention claimed and disclosed herein pertains to staplers, and in particular to automatic staplers for stapling a stack of sheets together.
BACKGROUND OF THE INVENTION
Automatic staplers are well known in the art. Such staplers can either be stand-alone units, or they can be integrated into another device. These integrated staplers and other finishing devices are often referred to as “in-line” devices. For example, many imaging apparatus, such as photocopiers and printers, can be configured with an automatic stapler for the stapling together of sheets of finished product. Frequently a stapler in a photocopier or a printer is part of a sorter-stacker attachment which can be used to sort, stack and collate sheets of finished product. Examples of such attachment devices incorporating staplers are described in U.S. Pat. Nos. 5,542,655 and 5,269,503, incorporated herein by reference. In the typical stapling process, a wire staple is driven into the top of a sheet stack by a stapling head. An anvil adjacent the back side of the sheet stack crimps the staple to thereby secure the sheets in the stack into a bound unit. The staples are typically provided in the form of a strip of pre-formed staple blanks which are attached to one another by glue or resin.
A common problem encountered by most stapling devices is that of using a staple of the proper size to staple together the sheet stack. A staple is defined by two essentially parallel legs which are joined in spaced-apart relationship by a crown portion. The legs of the staple should be at least as long as the thickness of the sheet stack to be stapled, otherwise the staple fails of its essential purpose, i.e., of holding all sheets in the stack together. Further, the legs of the staple should be of such a length that after the staple is driven into the sheet stack, the free ends protrude a sufficient distance beyond the last sheet to allow the free ends to be crimped around the back side of the sheet stack. Preferably, the free ends are crimped using a forming anvil so that the free ends are directed back towards the last sheet in the sheet stack. This not only helps to secure all of the sheets in the stack together, but also hides the sharp free ends of the staple which can cause injury and damage if they are left protruding beyond the bottom sheet in the stack. However, if the legs of the staple are much longer than the thickness of the sheet stack, then when the crimp is formed the free ends can actually be driven back through the sheet stack to thus protrude through the first sheet in the stack, presenting a hazard to persons handling the stapled sheet stack. This phenomenon can also damage the stapling head or cause it to jam. An oversized staple can also cause damage to the sheets in the sheet stack.
To address this problem of using a staple of the proper length, some staplers can accept different sized staples in the stapler, but only one size of staple is available for use by the stapler at any given time. This process requires a user to remove any staples which may be in the stapler and insert staples of the perceived correct size. It also requires that the user somehow be aware of the size of staples currently in the stapler. For stand-alone staplers this process is a relatively minor inconvenience, but for automatic in-line staplers used in imaging apparatus the process becomes more involved, and may even require the process to be performed by a trained technician.
Another solution to the problem is addressed by the use of a staple-forming device which forms a staple of the desired length from a reel of wire contained within the stapling apparatus. Such stapling apparatus are usually found in imaging apparatus, such as photocopiers. Examples of such stapling apparatus are described in U.S. Pat. Nos. 4,318,555 and 5,938,388. The apparatus described in the '555 patent is configured to form staples of two different lengths from two separate spools of wire. The apparatus described in the '388 patent forms a staple of a determined length from wire, using a sensor which detects the thickness of the sheet pack to determine the length of the staple. While these stapling apparatus may address the problem of using a staple of the proper length, the apparatus are quite complex.
What is needed then is a stapler which achieves the benefits to be derived from similar prior art devices, but which avoids the shortcomings and detriments individually associated therewith.
SUMMARY OF THE INVENTION
The present invention provides for a stapling apparatus which can contain at least two different sizes of staples (i.e., staples having different leg lengths) and can make any of the (two or more) staples available for use at any given time without requiring a user to remove and install staples. The staple most appropriate for stapling a given sheet stack can be selected from among the different sized staples which are provided in the stapler. The staples can either be provided in a strip of pre-formed staples, or they can be formed from a flat stack of pre-cut lengths of wire stock. The stapler can be provided with a sensor or other means to determine or estimate the thickness of the sheet stack. The stapler can also be provided with a controller which can use information from the sensor or other means to determine which staple available in the stapler should be used, based on the thickness of the sheet stack and the leg length of the staple. The stapler can be a stand-alone unit, or it can be part of an imaging apparatus (such as a photocopier or a printer). When the stapler is part of a copier or a printer (generically, “imaging device”), then the imaging device can be provided with a processor that can determine the number of pages in each sheet stack of a print job, and can also determine the media thickness of each sheet in the sheet stack. The processor can then determine the estimated thickness of the sheet stack, and this information can be used to select the staple most appropriate for stapling the sheet stack.
One embodiment of the present invention provides for a stapler for driving a staple into a sheet stack defined by a plurality of sheets. The stapler comprises a first cartridge configured to receive a first staple defined by a first leg length, and a second cartridge configured to receive a second staple defined by a second leg length. Preferably, the staples are provided to the cartridges in the form of strips of staples which are removably attached to one another. The stapler has a stapling head configured to drive the staples into the sheet stack. The stapler further includes a cartridge positioning actuator configured to selectively position either the first cartridge or the second cartridge in line with the stapling head. In one configuration the cartridge positioning actuator comprises a first solenoid having an extensible arm in mechanical communication with the first cartridge. The cartridge positioning actuator can further include a second solenoid having an extensible arm in mechanical communication with the second cartridge. In another configuration the cartridge positioning actuator comprises a linear motor having a body and a slide portion configured to slidably move with respect to the body, and the first cartridge is supported by the slide portion. The second cartridge can also be supported by the slide portion of the linear motor. It should be appreciated that the stapler can include more than two cartridges to thereby provide to a user of the stapler a wider selection of staples.
The stapler can further include a controller configured to actuate the cartridge positioning actuator in response to receiving an input signal. A sensor or other means configured to detect or estimate the thickness of the sheet stack can be provided. The sensor can generate a thickness signal in response to detecting the thickness of the sheet stack, and the controller can use the thickness signal as the input signal for actuating the cartridge positioning actuator. In this way the controller, in conj
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