Printers, printer spindle assemblies, and methods for determining media width for controlling media tension

Printer spindle assembly is provided including media spindle having first end and second end, a commutator disposed circumferentially at first end, at least two brushes in electrical contact with commutator and connected to voltage source, a plurality of electrically conductive springs serially disposed on media spindle in electrical communication with commutator, and a continuous electrically conductive path formed of electrically resistive material disposed along longitudinal axis of media spindle and configured to be in electrical contact with first spring end of one or more electrically conductive springs in the compressed state to form series circuit. Voltage source, brushes, and commutator form closed electrical circuit. Each electrically conductive spring is configured to be in uncompressed state in absence of media on media spindle and one or more of electrically conductive springs is configured to be in compressed state in presence of media on media spindle.

FIELD OF THE INVENTION

The present invention relates to printers and, more particularly, relates to printer spindle assemblies and methods for determining media width for controlling media tension.

BACKGROUND

Generally speaking, printers employ media on printer spindle assemblies. As used herein, “media” is any consumable product used in the printer (e.g., labels, receipts, ink ribbon, etc.). The term “media” includes “print media” on which the printer prints as well as the ink ribbon that may supply ink. Media of different widths have different torque requirements. Incorrect torque (i.e., media tension) may result in poor print quality, media wrinkles, print registration problems, black bending on printouts, and in some case, media rupture (collectively “printing problems”). Thus, it is important for the media tension to be set appropriate to the media width.

While systems exist to automatically sense the size of print media loaded into a printer by having an electrical feedback connected to the media size adjustment mechanism, such systems do not tell the printer or user anything about the proper torque values (i.e., media tension) to be used for any given printing job and for media other than print media.

Therefore, a need exists for printers, and printer spindle assemblies thereof and methods for automatically determining media width for controlling media tension.

SUMMARY

Accordingly, in one aspect, the present invention embraces a printer spindle assembly comprising a media spindle having a first end and a second end, a commutator disposed circumferentially at the first end of the media spindle, at least two brushes in electrical contact with the commutator and connected to a voltage source, a plurality of electrically conductive springs serially disposed on the media spindle in electrical communication with the commutator, and a continuous electrically conductive path formed of electrically resistive material disposed along a longitudinal axis of the media spindle and configured to be in electrical contact with a first end of the one or more electrically conductive springs in the compressed state to form a series circuit. The voltage source, the at least two brushes, and the commutator form a closed electrical circuit. Each electrically conductive spring is configured to be in an uncompressed state in the absence of media on the media spindle and one or more of the electrically conductive springs is configured to be in a compressed state in the presence of the media on the media spindle.

In another aspect, the present invention embraces a printer comprising a spindle assembly and a processor. The spindle assembly comprises a media spindle having a first end and a second end, a commutator disposed circumferentially at the first end of the media spindle, at least two brushes in electrical contact with the commutator and connected to a voltage source, a plurality of electrically conductive springs serially disposed on the media spindle in electrical communication with the commutator, and a continuous electrically conductive path formed of electrically resistive material disposed along a longitudinal axis of the media spindle and configured to be in electrical contact with a first end of the one or more electrically conductive springs in the compressed state to form a series circuit. The voltage source, the at least two brushes, and the commutator form a closed electrical circuit. Each electrically conductive spring is configured to be in an uncompressed state in the absence of media on the media spindle and one or more of the conductive springs is configured to be in a compressed state in the presence of the media on the media spindle. The processor is configured to determine a width of the media loaded on the media spindle based on the resistance of the series circuit and is configured to adjust torsion on the media based upon the determined width of the media.

In another aspect, the present invention embraces a method comprising loading media on a media spindle of a printer spindle assembly. The media spindle has a first end and a second end and the printer spindle assembly comprises a commutator disposed circumferentially at the first end of the media spindle, at least two brushes in electrical contact with the commutator and connected to a voltage source, a plurality of electrically conductive springs serially disposed on the media spindle in electrical communication with the commutator, and a continuous electrically conductive path formed of electrically resistive material disposed along a longitudinal axis of the media spindle and configured to be in electrical contact with a first end of the one or more electrically conductive springs in the compressed state to form a series circuit. The voltage source, the at least two brushes, and the commutator form a closed electrical circuit. Each electrically conductive spring is configured to be in an uncompressed state in the absence of the media on the media spindle and one or more of the electrically conductive springs is configured to be in a compressed state in the presence of the media on the media spindle. At least two brushes are connected to a voltage source. An electrical resistance of the series circuit is determined. A width of the media loaded on the media spindle is determined from the electrical resistance.

DETAILED DESCRIPTION

The present invention embraces printers, and printer spindle assemblies thereof and methods for automatically determining media width for controlling media tension. Various embodiments provide an automatic system that can sense the width of media disposed on a printer spindle assembly and feedback this information to an onboard processor that can implement torque requirements to achieve correct media tension.

Various embodiments of the present invention will be described in relation to a thermal transfer printer such as depicted inFIG. 1. However, the present invention may be equally applicable to other types and styles of printers (e.g., a thermal direct printer, a laser toner printer, an ink drop printer, etc.). As used herein, the term “printer” refers to a device that prints text, barcodes and other information-bearing symbols, illustrations, etc. onto non-continuous and continuous print media as hereinafter described (e.g., labels, receipts, paper, etc.). Non-continuous print media may comprise a liner portion underlying a plurality of individual print medium (a print medium portion) (e.g., a label) to define a liner only portion between each of the individual print medium. The individual print medium may be separated on the liner by gaps, holes, notches, black marks, etc. As used herein, “media” is any consumable product used in the printer (e.g., labels, receipts, ribbon, etc.). The term “media” includes “print media” on which the printer prints as well as the ribbon that may supply ink that transfers onto the print media.

Referring now specifically toFIG. 1, according to various embodiments of the present invention, an exemplary (thermal transfer) printer14capable of printing on print media is partially shown. The depicted printer14has a body32for enclosing an interior thereof. A moveable cover that forms a portion of the body is removed inFIG. 1for purposes of illustration. The moveable cover permits access to, for example, the interior of the body32and the components contained therein.

In the case of a thermal transfer printer such as depicted inFIG. 1, there may be at least one printer spindle assembly20contained within the body32, in accordance with various embodiments of the present invention.FIG. 1depicts printer spindle assembly20configured to hold a ribbon supply roll22and another printer spindle assembly20configured to hold a print media supply roll23within the body of the printer.

The ribbon supply roll and the print media supply roll comprise exemplary “media rolls”. As hereinafter described, a media roll is configured to be disposed on a media spindle24of the printer spindle assembly20. For example, the ribbon supply roll comprising ribbon (exemplary media) wound on a media supply spool is configured to be disposed on a media spindle comprising a ribbon supply spindle. The print media supply roll comprising print media wound on a print media supply spool is configured to be disposed on a media spindle comprising a print media supply spindle. As used herein, the media width is equivalent to the media roll width. The media spindle comprises a hollow elongated substantially cylindrical member comprised of a nonconductive material according to various embodiments of the present invention. A ribbon rewind spindle44on which unwound ribbon is wound up may also be contained within the body32. Each of the media spindles and the media rolls disposed thereon are configured to rotate.

The printer14further comprises a processor33. As known in the art, the central processing unit (CPU) (i.e., the processor33) is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output (I/O) operations specified by the instructions as hereinafter described. According to various embodiments of the present invention as hereinafter described, the processor is configured to determine the width of the media loaded on the media spindle through feedback from resistance circuitry coupled to the processor. Once the media width is known to the processor, the processor causes an adjustment in media tension in accordance with the media width. The processor is further configured to implement torque requirements of the printer. By adjusting the torque requirements, the media tension is changed. The processor may be configured to send information on the width of the media loaded on the media spindle to a display35on the printer.

The printer further comprises other illustrated and non-illustrated components as known in the art. For example, the printer may further comprise one or more motors (not shown) for rotating the media spindle(s) and the media rolls disposed thereon, and a user interface34for communication between a user and the printer14. The user interface34may include, but is not limited to, the printer display35for displaying information, including information on the width of the media loaded on the media spindle.

Returning now toFIG. 2, according to various embodiments of the present invention, the printer spindle assembly20comprises the media spindle24having a first end24aand a second end24b, a commutator26(not shown inFIG. 1) disposed circumferentially at the first end24aof the media spindle, at least two (carbon) brushes28(not shown inFIG. 1) in electrical contact with the commutator26and connected to a voltage source, a plurality of electrically conductive springs (e.g.,30a-30h) serially disposed on the media spindle24in electrical communication with the commutator, and a continuous electrically conductive path40formed of electrically resistive material disposed along a longitudinal axis of the media spindle and configured to be in electrical contact with a first spring end portion34-1of one or more of the electrically conductive springs in the compressed state to form a series circuit. The media spindle24, the plurality of electrically conductive springs (e.g.,30a-30hin the depicted embodiment), and the continuous electrically conductive path40comprising the electrically resistive material comprise a rotational potentiometer. The width of the spring can be selected to accommodate the media width.

The electrically conductive spring30are electrically linked to the commutator26. The carbon brushes28are disposed generally on either side of the commutator26. The voltage source, the carbon brushes, and the commutator form a closed electrical circuit. The closed electrical circuit connects the electrical circuits in series to a main electrical control unit housing the processor33(FIG. 1) of the printer. A meter comprising an analog to digital converter (ADC) is coupled to the processor33. The ADC provides an isolated measurement that converts an analog voltage or current to a digital number proportional to the magnitude of the voltage or current. The processor is configured by a software program to implement torque requirements to achieve correct media tension as hereinafter described.

Still referring toFIG. 2and now toFIGS. 3, 6, and 7B, the plurality of electrically conductive springs (30a-30hinFIG. 2) disposed on the media spindle24are generally C-shaped. Suitable exemplary electrically conductive springs include a leaf spring/coil spring. Each electrically conductive spring30comprises a pair of conjoined electrically conductive spring portions having a space therebetween to impart compressibility to each electrically conductive spring. Each electrically conductive spring has two spring ends, the first spring end34and a second spring end36. The first spring end34gets compressed. The first spring end34has a first portion34-1facing a first direction that is used to contact the resistive material and a second portion34-2facing a second opposing direction that provides a surface for the media roll to contact and compress the first spring end34. As noted previously, the first spring end34is configured to be compressed (deflected) when a media roll (e.g., ribbon supply roll22) is disposed on the media spindle24. The second spring end36of each electrically conductive spring is configured to be received and retained in a groove38(seeFIG. 7B) in the media spindle. Each electrically conductive spring is metallic.

In the depicted embodiment ofFIG. 2, the printer spindle assembly has eight electrically conductive springs. In the depicted embodiment ofFIG. 3, the printer spindle assembly has four electrically conductive springs; however other numbers of electrically conductive springs are possible. The first electrically conductive spring disposed near the first end of the media spindle is contiguous to the commutator. The subsequent electrically conductive springs are spaced apart in serial arrangement on the media spindle in the direction of the media spindle second end. The electrically conductive springs remain in an uncompressed state when no media roll is loaded on the media spindle of the printer spindle assembly.

When a media roll is disposed on the media spindle of the printer spindle assembly, the media roll compresses one or more of the electrically conductive springs. The media roll will contact the second portion34-2and then the first portion34-1of the electrically conductive springs will touch the conductive path40as noted previously. Therefore, each electrically conductive spring is configured to be in an uncompressed state in the absence of media on the media spindle and one or more of the electrically conductive springs is configured to be in a compressed state in the presence of the media on the media spindle. InFIG. 2, electrically conductive springs30a-30fare in a compressed state and electrically conductive springs30g-30hare in an uncompressed state. InFIG. 3, electrically conductive springs30a-30care in a compressed state and electrically conductive spring30dis in an uncompressed state. InFIG. 6, electrically conductive spring30fis in the compressed state and electrically conductive spring30gis in the uncompressed state.

The electrically conductive springs have a length such that when one or more of the electrically conductive springs are compressed, the first spring end of the compressed electrically conductive spring(s) will make electrical contact with the continuous electrically conductive path40, resulting in current29flow (e.g.,FIGS. 3, 5A, 5B, and 7A), thereby completing an electrical circuit in series with the closed electrical circuit of the voltage source, the carbon brushes, and the commutator. The continuous electrically conductive path40may be a strip of electrically resistive material such as carbon or may have another form that is disposed along a longitudinal axis of the media spindle. Each electrically conductive spring in electrical contact with the continuous electrically conductive path40decreases an amount of the electrically resistive material in the series circuit. The amount of the continuous electrically conductive path in the series circuit and therefore resistance in the series circuit increases with a decrease in a width of the media.

InFIG. 2, the media roll covers and engages the commutator and compresses electrically conductive springs30athrough30f. Thus six additional electrical circuits in series are added to the closed electrical circuit consisting of the voltage source, the carbon brushes, and the commutator. The electrically conductive springs30gand30hremain uncompressed inFIG. 2.

InFIG. 3, the media roll covers and engages the commutator and compresses electrically conductive springs30athrough30c. Electrically conductive spring30dremains uncompressed inFIG. 3. Thus, three additional electrical circuits in series are added to the closed electrical circuit consisting of the voltage source, the carbon brushes, and the commutator. The path of electrical current29is shown passing through the electrical circuits connected in series inFIG. 3.

The media width is determined from the difference in electrical resistance caused by compression of the electrically conductive springs contacting the continuous electrically conductive path40(see, e.g.,FIG. 4AversusFIG. 4B). Thus, as depicted inFIGS. 4A and 4B, the overall resistance of the series circuit will change depending on how many electrical circuits are connected in series to the closed electrical circuit. When a resistance meter is placed in the electrical circuit, the change in resistance can be measured when a media roll is loaded on the media spindle indicating how many electrically conductive springs have been compressed and thus how many electrical circuits are added to the circuit. For example, the width of the media/media roll inFIG. 4Ais greater than the width of the media/media roll inFIG. 4B. Therefore, the overall resistance (R2) inFIG. 4Bis greater than the resistance (R1) inFIG. 4A.FIG. 8Adepicts a series circuit used in the methods according to various embodiments as compared with the conventionally used parallel circuit depicted inFIG. 8B.

Returning again toFIG. 1, according to various embodiments of the present invention, and as noted previously, the printer comprises the processor33. The processor is configured to determine the width of the media/media roll loaded on the media spindle based upon the measured resistance as determined from the resistance circuitry (the meter). Once the media width is known to the processor, the processor causes an adjustment in media tension in accordance with the media width. The processor may be configured to send information on the width of the media/media roll loaded on the media spindle to the display on the printer.

Referring now toFIG. 9, according to various embodiments of the present invention, a method900for controlling media tension is provided. The method900for controlling media tension generally comprises loading media (more particularly, the media roll) on the media spindle of the printer spindle assembly (step910), connecting the at least two brushes to the voltage source (step920), determining the electrical resistance of the series circuit (step930), and determining, from the electrical resistance, a width of the media/media roll loaded on the media spindle (step940).

Determining the electrical resistance of the series circuit comprises measuring the electrical resistance. The electrical resistance may be measured, for example, with an ohmmeter. Other ways of determining the electrical resistance of the series circuit are contemplated according to various embodiments of the present invention.

Determining the width of the media from the electrical resistance comprises identifying the width of the media that is associated with the electrical resistance. Each different electrical resistance value may be associated with a different width of the media, such as in a look-up table.

From the foregoing, it is to be appreciate that various embodiments automatically determine media width for controlling media tension. Various embodiments provide an automatic system that can sense the width of media/media roll disposed on a printer spindle assembly and feedback this information to an onboard processor that can implement torque requirements to achieve correct media tension, thereby avoiding printing problems associated with using an incorrect media tension.

To supplement the present disclosure, this application incorporates entirely by reference the following commonly assigned patents, patent application publications, and patent applications:

U.S. Patent Application Publication No. 2017/0200108; and