Winding – tensioning – or guiding – Unwinding – With detector – indicator – or control
Reexamination Certificate
2001-02-27
2004-07-27
Nguyen, John Q. (Department: 3654)
Winding, tensioning, or guiding
Unwinding
With detector, indicator, or control
C242S563200
Reexamination Certificate
active
06766977
ABSTRACT:
DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates to sheet material dispensers in general. More particularly, the present invention relates to sheet material dispensers capable of dispensing individual sheets from a roll of sheet material. The individual sheets are defined by rows of perforations in the sheet material.
2. Background of the Invention
Sheet material dispensers are designed to dispense individual sheet material from various sources including folded sheet material and rolled sheet material. Each type of sheet material source requires a different means of dispensing the sheet material. As a result, each source has unique problems in controlling how much sheet material is dispensed, and how quickly more sheet material is made available.
Folded sheet material dispensers contain separate sheets of folded sheet material that are dispensed through an opening. When a user removes a single sheet from the opening, another individual sheet is instantly made available. As a result, several sheets can be removed at once. Because the sheets are so readily available, there is no real limit to how many sheets can be removed by the user. Therefore, folded sheet material dispensers must by constantly checked to make sure they are full.
One common type of sheet dispensers dispenses sheet material wound on rolls. These dispensers have several different means of dispensing paper. The sheets can be removed by either pulling on a free end of a sheet or actuating a lever to advance the sheet. These dispensers usually have a cutter to sever the individual sheet from the source of sheet material. The cutter can be arranged adjacent to the opening, in which case the user removing the sheet must force the sheet against the cutter. Otherwise, the cutter is formed as part of a cutting drum mechanism.
The most simple dispensers rely on the user to pull on a free end of sheet material, thereby causing the sheet material to be dispensed. The amount of force necessary to dispense the sheet material depends in part on the location of the cutter. It takes more force to remove an individual sheet where the cutter is part of a cutting drum mechanism as compared to when the cutter is located adjacent to the opening. When the cutter is part of the cutting drum mechanism, it is the rotational momentum of the cutting drum that severs the individual sheet from the sheet material roll. To obtain the required amount of rotational momentum, the user has to apply more force than simply pulling the sheet material against the cutter.
Due to relatively recent advances in paper making technology that permit relatively easy formation of perforations in sheet material, there are now a number of dispensers capable of dispensing sheet material having spaced rows of preformed perforations. Such perforations weaken the sheet material, making it easier to separate an individual sheet from the remainder of sheet material. Some conventional dispensers for this type of sheet material have drawbacks and disadvantages. For example, these dispensers are designed so that after an individual sheet is dispensed, a sufficient length (tail end) of sheet material normally remains extended from the dispensing outlet to be grasped by the next user. Sometimes, however, when the sheet material tears along a perforation line positioned inside the dispenser, there is little or no exposed length of sheet material that can be grasped. In some cases, this requires the next user to actuate a manual lever or crank that could spread germs or other contaminants from one user to another.
The present inventors have proposed to improve sheet material dispensing by providing a sheet material dispenser with perforation detecting capability, for example. Such detection, however, is challenging because the translucence of the some types of sheet material may provide false indications of perforations.
In light of the foregoing, there is a need in the art for an improved dispenser and method for dispensing sheet material.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a dispenser for dispensing sheet material and a method of dispensing that substantially obviate one or more limitations of the related art. In one advantageous aspect, the present invention facilitates dispensing of individual sheets from a source of sheet material having a plurality of spaced perforations.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention includes a dispenser for dispensing sheet material including a plurality of spaced perforations. The dispenser includes a housing defining an interior for accommodating a source of the sheet material, and an outlet through which the sheet material is dispensed. A perforation sensor is configured to sense perforations in the sheet material, and this perforation sensor is disposed in the interior of the housing. The perforation sensor includes at least one light receptor, and at least a portion of the perforation sensor is positioned in the housing to contact sheet material traveling from the source to the outlet, thereby spreading perforations in the sheet material.
In another aspect, the portion of the perforation sensor is a light emitter configured to emit light capable of being detected by the light receptor. The light emitter and the light receptor are spaced apart from one another such that the sheet material can be positioned between the light emitter and light receptor. This allows light to pass from the emitter to the receptor via the perforations, where the spreading of the perforations increases the amount of light passing through the perforations.
In yet another aspect, the sheet material is dispensed in a first direction. The perforation sensor is located in the housing such that the portion of the perforation sensor contacts the approximate middle of the sheet material in a second direction perpendicular to said first direction.
In another aspect, the dispenser further includes at least one rotatable roller in the housing. At least a portion of the sheet material is in contact with the roller when the sheet material travels from the source to the outlet.
In a further aspect, the roller includes at least two spaced sections and the portion of the perforation sensor is positioned between the roller sections to contact sheet material on the rollers.
In an additional aspect, the dispenser includes a brake configured to brake rotational movement of the roller and a controller for controlling the brake. The controller is in electrical communication with the perforation sensor.
In yet another aspect, the brake includes a detent member coupled to the roller, and a solenoid mounted to the housing. The detent member has a plurality of detents provided thereon, the solenoid has a plunger configured to selectively engage a respective one of the detents.
In another aspect, there are two light receptors. The perforation sensor also includes a differential trans-impedance amplifier for detecting light incident upon the two light receptors.
In a further aspect the differential trans-impedance amplifier is configured as a balanced bridge for amplifying the difference in intensity of light detected by the two light receptors.
In an additional aspect the differential trans-impedance amplifier includes a first operational amplifier, a second operational amplifier, a feed back resistor, a scaling resistor, and a gain resistor. The first operational amplifier has an inverting input node, a non-inverting input node, and an output node. The second operational amplifier has an inverting input node, a non-inverting input node, and an output node. The feedback resistor has a first end and a second end, wherein the first end is electrically coupled to the inverting input node of the first operational amplifier. The scaling resistor has a first end and a second end. The first end of the scaling resistor is electrically coupled to the second end of the feedback resistor and the second end of the
Broehl Joshua M.
Denen Dennis J.
Knittle John J.
Finnegan Henderson Farabow Garrett & Dunner LLP
Georgia-Pacific Corporation
Nguyen John Q.
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