A light guide apparatus includes a light guide layer having a top surface and a bottom surface, and a transversely oriented side-end surface that forms an output aperture of the light guide, characterized by an index of refraction, n1, and further characterized by a length dimension in an intended light propagation direction towards the output aperture, where the intended light propagation direction is a z-axis direction of a Cartesian coordinate system; and a plurality of light injection elements disposed in the form of at least one linear strip in at least one of the top and bottom surfaces of the light guide layer, wherein some of the plurality of light injection elements are disposed on one lateral side of the strip and some other of the plurality of light injection elements are disposed on an opposing lateral side of the strip at a rotation angle Δz about the y-axis.

The present disclosure relates to gel-type polymer electrolyte for a dye-sensitized solar cell, a dye-sensitized solar cell comprising the gel-type polymer electrolyte, and a method for manufacturing the dye-sensitized solar cell.

The present invention provides a photoelectric conversion material comprising a fullerene derivative represented by the formula C60(R1)5(R2), wherein each R1 independently represents an organic group having a substituent; and R2 represents a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group. Further, the present invention also provides a photoelectric conversion device having a self-assembled monomolecular film of the photoelectric conversion material, and a solar cell having the photoelectric conversion device.

A conductive paste may include a conductive component and an organic vehicle. The conductive component may include an amorphous metal. The amorphous metal may have a lower resistivity after a crystallization process than before the crystallization process, and at least one of a weight gain of about 4 mg/cm2 or less and a thickness increase of about 30 μm or less after being heated in a process furnace at a firing temperature.

According to example embodiments, a conductive paste includes a conductive component that contains a conductive powder and a titanium (Ti)-based metallic glass. The titanium-based metallic glass has a supercooled liquid region of about 5K or more, a resistivity after crystallization that is less than a resistivity before crystallization by about 50% or more, and a weight increase by about 0.5 mg/cm2 or less after being heated in a process furnace at a firing temperature. According to example embodiments, an electronic device and a solar cell may include at least one electrode formed using the conductive paste according to example embodiments.

A method of photoplating a metal contact onto a surface of a cathode of a photovoltaic device is provided using light induced plating technique. The method comprises: a) immersing the photovoltaic device in a solution of metal ions, where the metal ions are a species which is to be plated onto the surface of the cathode of the photovoltaic device; and b) illuminating the photovoltaic device, using a light source of time varying intensity. This results in nett plating which is faster in a direction normal to the surface of the cathode than in a direction in a plane of the surface of the cathode.

A method for fabricating a photovoltaic device includes depositing a p-type layer at a first temperature and depositing an intrinsic layer while gradually increasing a deposition temperature to a final temperature. The intrinsic layer deposition is completed at the final temperature. An n-type layer is formed on the intrinsic layer.

A photovoltaic cell comprises a top subcell having a first band gap; a middle subcell comprising a substrate and having a second band gap, wherein the substrate comprises a first side and a second side opposite to the first side; and a bottom subcell having a third band gap, wherein the top subcell is grown on the first side of the substrate and the bottom subcell is grown on the second side of the substrate, wherein the first band gap is larger than the second band gap and the second band gap is larger than the third band gap.

Hemispheres and spheres are formed and employed for a plurality of applications. Hemispheres are employed to form a substrate having an upper surface and a lower surface. The upper surface includes peaks of pillars which have a base attached to the lower surface. The peaks have a density defined at the upper surface by an array of hemispherical metal structures that act as a mask during an etch to remove substrate material down to the lower surface during formation of the pillars. The pillars are dense and uniform and include a microscale average diameter. The spheres are formed as independent metal spheres or nanoparticles for other applications.

The present invention is that of a solar energy system that uses a light-guide solar panel (LGSP) to trap light inside a dielectric or other transparent panel and propagates the light to one of the panel edges for harvesting by a solar energy collector such as a photovoltaic cell. This allows for very thin modules whose thickness is comparable to the height of the solar energy collector. This eliminates eliminating the depth requirements inherent in traditional concentrated photovoltaic solar energy systems. A light guide solar panel has a deflecting layer, a light guide layer and a solar cell in optical communication with the light guide layer. The deflecting layer receives light at a first surface and inputs the light into the light guide layer. The light guide layer propagates the light to the solar cell, which is aligned generally parallel to the input surface.

A nano power cell and method of use are described wherein the nano power cell absorbs electromagnetic energy is nano particles in an optical fluid that flow in microchannels of the nano power cell.

The solar cell module includes a solar panel that includes a transparent substrate and is configured by aligning solar cells, a reinforcing frame arranged on the back surface of the solar panel, and a shock absorbing unit arranged between the solar panel and the reinforcing frame, where the shock absorbing unit has the first main surface facing the solar panel, which is a flat surface, and a second main surface facing the reinforcing frame, which is a curved surface bowed in the longitudinal direction of the reinforcing frame, having an arc shape in cross section, and convexed toward the reinforcing frame side.

A solar-cell sealant that has excellent properties such as transparency, flexibility, adhesiveness, heat resistance, appearance, cross-linking characteristics, electrical characteristics, and calenderability. A solar-cell sealant that contains an ethylene/α-olefin/unconjugated-polyene copolymer satisfying requirements (a1) through (a3). Requirement (a1) is that constituent units derived from ethylene constitute 80-90 mol %, constituent units derived from C3-20 α-olefin constitute 9.99-19.99 mol %, and constituent units derived from an unconjugated polyene constitute 0.01-5.0 mol % of said copolymer. Requirement (a2) is that the MFR of said copolymer, as measured in accordance with ASTM D1238 at 190° C. under a 2.16 kg load, be at least 2 g/10 min. and less than 10 g/10 min. Requirement (a3) is that the Shore A hardness of said copolymer, as measured in accordance with ASTM D2240, be 60 to 85.

A photovoltaic device including a substrate; a first electrode placed on the substrate; a second electrode which is placed opposite to the first electrode and which light is incident on; a first unit cell being placed between the first electrode and the second electrode, and including an intrinsic semiconductor layer including crystalline silicon grains making the surface of the intrinsic semiconductor layer toward the second electrode textured; and a second unit cell placed between the first unit cell and the second electrode.

A solar cell module includes a plurality of solar cells each comprising a substrate, an emitter region placed at the substrate, and an anti-reflection region placed on the emitter region. The anti-reflection region includes a first opening region through which part of the emitter region is exposed and one or more second opening regions through which part of the emitter region is exposed. A first electrode is connected to the exposed emitter region of the first opening region through the anti-reflection region by metal plating and a first bus bar is connected to the exposed emitter region of one or more second opening regions through the anti-reflection region by metal plating.

A surface of a photovoltaic cell is coated with a solution that includes barium titanate to reduce reflection of sunlight that is incident on the surface. The solution may include a base of polydimethylsiloxane and carbon nanotubes. The process may be used in the fabrication of new photovoltaic cell assemblies, or to retrofit existing assemblies in situ.

A thin-film solar cell includes a cell having a transparent electrode layer, a photoelectric conversion layer, and a back electrode layer stacked on a transparent insulation substrate. A plurality of cells are connected in series to constitute a cell string. A bus bar is arranged on the back electrode layer of an end cell constituting the cell string. The thin-film solar cell has a photoelectric conversion layer on a series-connection direction end of the transparent electrode layer. In plan view, a series-connection direction end of the back electrode layer at an end of the cell string and the series-connection direction end of the transparent electrode layer at the end of the cell string do not overlap, while the bus bar and the transparent electrode layer at the end cell constituting the cell string overlap at least partially. A method of fabricating the thin-film solar cell is provided.

Methods of forming a photovoltaic structures including nanoparticles are disclosed. The method includes electrospray deposition of nanoparticles. The nanoparticles can include TiO2 nanoparticles and quantum dots. In an example, the nanoparticles are formed on a flexible substrate. In various examples, the flexible substrate is light transparent. Photovoltaic structures and apparatus for forming photovoltaic structures are disclosed.

The present invention provides an organic thin film solar cell having a novel photoelectric conversion layer with superior conversion efficiency from light to electricity and superior carrier transportability to an electrode. The photoelectric conversion layer is arranged between a pair of electrodes at least one of which has optical transparency, and comprises a multilayer film formed by alternately laminating an electron-donating organic semiconductor thin film and an electron-accepting thin film. The electron-donating organic semiconductor thin film is formed by organic semiconductor molecules in which cyclic compounds are bound in a linear fashion.

A novel method and apparatus for performing the method is disclosed the apparatus comprises a laser (17), at least one ink jet print head (14), means for holding a transparent substrate having a transparent conductive layer, means (22) for adjusting the relative positions of the laser and at least one ink jet print head to the transparent conducting layer (2) and a controller to control the laser and ink jet print head whereby in a first step to inkjet print one or more coarse metal borders (15) onto the deposited TCM layer and in a second step by means of a single laser ablation process, ablating tracks in both the metal border and underlying TCM layer to form a plurality of discrete electrical busbars (12) and optionally also to form electrodes in the remainder of the TCM layer.

Provided is an organic light emitting device. The organic light emitting device comprising a first light emitting part on a substrate, emitting a first light of a first wavelength, wherein the first light emitting part includes a transparent first electrode, a first organic light emitting layer, and a transparent second electrode sequentially stacked on the substrate, a second light emitting part on the first light emitting part, emitting a second light of a second wavelength, wherein the second light emitting part includes a transparent third electrode, a second organic light emitting layer, and a reflective fourth electrode sequentially stacked on the first light emitting part, and a fluorescent material disposed at least one between the substrate and the first light emitting part, and between the first light emitting part and second light emitting part.

A multi-junction solar cell having a Ge or GaAs substrate, as well as a solar cell structure having several subcells deposited on the substrate, the substrate having peripheral side faces, and the solar cell structure having a peripheral circumferential surface, which runs spaced apart from the side faces. To prevent oxidation and penetration of moisture, the circumferential surface of the solar cell structure is coated with a protective, electrically insulating first coating under essential exclusion of the upper surface facing the rays, or that without encroaching on the solar cell structure, the side faces of the substrate are coated with a protective, electrically insulating second coating or that both the side faces of the substrate as well as the circumferential surface of the solar cell structure are coated with a third coating by essential exclusion of the upper surface facing the rays.

In one embodiment, a method for controlling drive settings in a press for printing on a web of media. A drive is provided to receive the web from an upstream location and to transport the received web downstream of the drive at a controllable speed. The speed of the drive is sampled plural times while operating the drive in a tension control mode that varies the speed to maintain a desired tension in the web adjacent the drive. An optimal speed of the drive is calculated from the sampled speeds. The drive is operated in a constant velocity mode at the optimal speed during printing.

An automatic circle forming apparatus adapted for automatically forming OPP (O-phenylphenol) plastic circles includes a lower equipment cabinet, a first base plate, a transmitting module, an automatic separating module, an automatic tearing film module, a sucking waste mechanism, a displacement module, an automatic forming module and an upper equipment cabinet. The upper equipment cabinet is positioned on the first base plate for installing the transmitting module, the automatic separating module, the automatic tearing film module, the sucking waste mechanism, the displacement module and the automatic forming module therein. The upper equipment cabinet is equipped with a man-machine control interface which connects with and controls the transmitting module, the automatic separating module, the automatic tearing film module, the sucking waste mechanism, the displacement module and the automatic forming module for automatically forming the OPP plastic circles so as to improve operation efficiency and save a human cost.

A continuous multi-layer film includes a support layer having a first film surface, and a hard coat layer, formed on the support layer, having a second film surface, and having a curling tendency in an inward direction. In the decurling method, the multi-layer film is transported. A first transition of the support layer in the multi-layer film being transported into a rubber phase is induced by supplying fluid vapor on the support layer. After supplying the fluid vapor, a second transition of the support layer from the rubber phase into a glass phase is induced. The multi-layer film is transported while a portion of the support layer in the rubber phase is prevented from contacting a solid object. The hard coat layer is formed from a polymer produced from an ultraviolet curable compound, and the support layer is formed from cellulose acylate.

A surface treatment equipment is designed for forming nickel barriers on a plurality of terminals for preventing solder wicking is disclosed. The surface treatment equipment includes a retractable feeding system, a laser engraving system, an image sensor, and a control system. The retractable feeding system is utilized to transmit a strip that has the terminals. The laser engraving system is utilized to ablate the terminals. The image sensor is utilized to collect a plurality of images of the ablated terminals. The control system receives the images to perform image recognition. When a defective terminal is recognized, the control system controls the retractable feeding system to transmit in reverse and controls the laser engraving system to repeatedly ablate the defective terminal. The defective terminals can be automatically recognized by the image sensor accompanying the control system. Thus, the drawback of a human visual inspection is solved.

A method of adjusting a lateral position of an endless belt that is passed around at least two rollers, comprising the steps of: controlling a tilt position of a first roller of the at least two rollers; and adjusting a lateral position of the first roller, wherein the lateral position of the first roller is adjusted in combination with controlling the tilt position of the first roller.

A roll-to-roll printing system includes driven rolls to apply a feeding force to a flexible substrate so that the flexible substrate is fed from an unwinder to a rewinder, nip rolls respectively disposed above two opposite end portions of each of the driven rolls to pressurize two opposite side portions of the flexible substrate, nip roll driving motors connected to the nip rolls to rotate the nip rolls, and a control unit to receive information regarding change of torque values of the nip roll driving motors and control tension of the flexible substrate based on the information.

A printing material web processing machine, in particular a web-fed rotary offset press, has at least one press cylinder for printing the web, a dryer disposed downstream of the press cylinder, which guides the web along a path, and at least a first pull roll disposed downstream of the dryer to convey the web along the path with a given tensile stress. The web processing machine further has a first apparatus disposed downstream of the press cylinder and upstream of the dryer for separating the web from the press cylinder, and a second apparatus for driving the first pull roll, which drives the first pull roll at a rotational speed that is reduced as compared with the rotational speed of the press cylinder.

A method is disclosed for controlling at least one machining device which is coupled to a machine tool by means of an encoder signal, the machine tool having at least one motion control device. In order to improve the accuracy of the encoder connection, at least one additional variable which characterizes the transport is digitally transmitted from the motion control device to the at least one machining device and is used to correct the encoder signal.

An apparatus of correcting belt-meandering for a secondary battery is disclosed. In one embodiment, the apparatus includes i) upper and lower rollers configured to receive a base material therebetween, wherein the base material comprises positive and negative electrode materials and an insulating material interposed between the electrode materials and ii) a driver portion configured to rotate the upper and lower rollers such that the base material is transferred in a first direction during the rotation. The apparatus may also include i) a support portion configured to support shafts of the driver portion and the upper and lower rollers and ii) a transverse moving mechanism configured to move the support portion in a second direction substantially perpendicular to the first direction.

In a case where components such as side flaps and crotch portions are arranged on multiple webs which are being conveyed while being arranged side by side in the width direction of the webs, articles in various sizes can be handled easily by a web conveying step of conveying a front waistline web 11A and a back waistline web 11B the webs being arranged side by side in a width direction of the webs, a flap attaching step of attaching side flaps 30 onto the web 11 of the front waistline web 11A or the back waistline web, a web gap changing step of changing a gap between the front waistline web 11A and the back waistline web 11B by a web gap changing mechanism 500 and a crotch member attaching step of attaching a crotch member 20 between the front waistline web 11A and the back waistline web 11B, wherein the web gap changing step is performed between the flap attaching step and the crotch member attaching step.

A feeding apparatus feeds a metal strip with cutaway portions in a conveying direction and includes: a reference plate on which the metal strip is placed and in which a slit is formed; moving bodies that are provided below the reference plate and are moved by driving means parallel to the reference plate in the conveying direction; feed pins that advance into the cutaway portions, are provided on the moving bodies so as to move up and down with respect to the reference plate, and pull the metal strip in the conveying direction when the moving bodies move; and at least one guide portion that contacts a side surface on an opposite side of the metal strip to the cutaway portions and guides conveyance of the metal strip.

A method for regulating a web tension in a processing machine for processing a product web, in particular a shaftless printing press, includes separating a first product-web section from a second product-web section by a delay section. The web tensions in the first and second product-web sections are influenced by first and second actuators, respectively. To regulate the web tension in the first product-web section, the method further includes defining a regulation output value from which an actuating command for the first actuator is derived. An actuating command for the second actuator is defined from the regulation output value and a delay element to decouple the web tension in the second product-web section from the regulation of the web tension in the first product-web section. The delay element delays the effect of the regulation output value on the actuating command for the second actuator by a delay time.

A tape feeder includes a guide part that guides a carrier tape and is detachably attached to a main body. The guide part includes: a lower member guiding the carrier tape and attached to and detached from the main body; an upper member pressing down the carrier tape from above; a tape introduction part guiding the carrier tape into the upper member at an upstream side thereof in a tape feed direction; a confirmation opening part disposed in the upper member for visually confirming that the carrier tape arrives at a pin engagement range; an open/close mechanism opening and closing the upper member with respect to the lower member; and a positioning mechanism fitting a positioning pin into a feed hole of the carrier tape in the guide part, thereby positioning the carrier tape relative to the guide part in the tape feed direction.

A vacuum roller for a web handling system comprises a hollow, cylindrical, rotably driven drum and an end cap threadingly mounted onto the rear end of the drum. Together, the drum and the end cap define a plurality of individual, externally communicable vacuum paths. A spherical, metal movable element is internally disposed within each vacuum path and regulates the passage of air therethrough. A plurality of magnetic elements is fixedly mounted on a stationary annular holder. In use, each magnetic element selectively displaces each movable element when disposed in close proximity thereto to the extent necessary so as to permit the passage of air through its corresponding vacuum path. As such, the vacuum roller is provided with a predefined range of suction, or vacuum zone, about the outer surface of its rotating drum that directly corresponds to the angular arrangement of the plurality of stationary magnetic elements.

To provide a wire unwinding auxiliary device capable of, compared to a conventional device, effectively preventing an unwound wire material from getting twisted, entangled or flawed. A wire unwinding auxiliary device used for guiding an unwound wire material when unwinding the wire material which is wound in a coiled shape. The device comprises a plurality of rotation members 1a-1e on which the unwound wire material is set to run therethrough, and a non-rotation member 2 provided adjacent to at least a rotation member 1a through which the wire material passes first in the plurality of rotation members 1a-1e, thereby a running path of the wire material is stabilized between the non-rotation member 2 and the rotation member 1a.

A media diverter system for directing a media sheet traveling along an input media path into either a first media path or a second media path. One or more roller assemblies are provided including a media-guiding roller having one or more grooves formed around the exterior surface, and an air source for selectively providing an air flow into one or more of the grooves, the air flow being directed between the media sheet and the exterior surface of the media-guiding roller thereby producing a Bernoulli force to draw the media sheet toward the media-guiding roller. A controller selectively activates the air source in at least one of the roller assemblies while the corresponding media-guiding roller rotates around its roller axis to draw the media sheet toward the exterior surface of the media-guiding roller, thereby directing the media sheet into either the first media path or a second media path.

An automatically-adjusting tensioning mechanism for use in a roll-fed web media transport system, the tensioning mechanism adding tension to the web media, comprising a bracket assembly being adapted to freely pivot around a pivot axis, and first and second tensioning shoe having curved surfaces attached to the bracket assembly. The web media feeds through the tensioning mechanism in an S-shaped media path where the web media is wrapped around the first and second tensioning shoes. The pivot angle of the bracket assembly automatically adjusts in response to differences in a coefficient of friction between the web media and the tensioning shoes such that the tension in the web media has a reduced level of variability relative to configurations where the bracket assembly is held in a fixed position.

A web conveying apparatus that conveys a web, includes: a transverse position displacement detection unit that detects a transverse position displacement of the web; a transverse position correction unit that corrects a transverse position of the web by a guide roller; width detection units that detect a width size in a left-right direction of the web; and a control unit that controls the transverse position correction unit in accordance with the transverse position displacement detected by the transverse position displacement detection unit and performs feedback control to position the web in a target position. The control unit changes a correction amount in the feedback control in accordance with the width size of the web detected by the width detection units.

In a multiple endless belt type band sheet coiling tension applying apparatus in which a coiling tension is applied to slit band sheets a by a frictional force generated by slippage between belt pressing surfaces 4a, 5a and internal belt surfaces 1a of endless belts 1, a friction plate 8 made of a thin metallic sheet having heat conductivity equal to or better than that of the belt pressing units 4a, 5a is detachably installed on a front surface of each of the belt pressing units 4a, 5a.

A film transport apparatus includes: an edge sensor that detects a lateral position deviation of a film; a lateral position correction device that corrects a lateral position of the film with a guide roll; a tension sensor that detects tensions applied respectively near left and right ends of the film; and a control unit that executes feedback control such that the lateral position correction device is controlled on the basis of the lateral position deviation detected by the edge sensor so that the film is located at a target position. The control unit changes the feedback control based on a left and right tension difference, which is a difference between the tension applied near the left end of the film and the tension applied near the right end of the film, the tensions being detected by the tension sensor.

A buffer store for a flat web material includes two roller registers having freely rotatable rollers movable relative to one another in a direction radial to a roller axis, thereby forming loops of the web material between the rollers, a piston-cylinder arrangement having a chamber containing a compressible medium and acting as a spring between the registers to generate web tension in the material, and a control-valve arrangement that switches between a first condition, for normal operation, and a second condition, for operation during a fault. In the first condition, the control-valve arrangement connects the cylinder chamber of the piston-cylinder arrangement to a device for providing a constant operating pressure. In the second condition, the control-valve arrangement closes the cylinder chamber of the piston-cylinder arrangement and connects it to a relief valve that relieves pressure therein to a residual pressure significantly smaller than the operating pressure.

A wire-processing machine or apparatus includes a wire-feeding apparatus for guiding a wire, wherein the wire-processing machine or apparatus contains a wire drive for forward movement of the wire and a guide pipe with an entry opening and an exit opening. The wire-processing machine or apparatus contains a swivel unit with drive and a wire-gripping apparatus which is arranged on a swivel arm, wherein an exit side end of the guide pipe is fastened to the swivel arm. The wire drive and the guide pipe are arranged in such manner that the wire can be shot-in through the guide pipe. The wire-feed apparatus further contains a length-compensating unit which is arranged in the area of the guide pipe and which, in a first state, shortens an effective length of the guide pipe and, in a second state, lengthens the effective length of the guide pipe.

An accumulating apparatus (4) has an upper arm (51) in which a plurality of upper rollers (511) are arranged, and a lower arm (52) in which a plurality of lower rollers (521) are arranged. An upper gear (61) is fixed to the upper arm and a lower gear (62) is fixed to the lower arm. The upper gear is engaged with the lower gear so that the upper arm and the lower arm are simultaneously moved in opposite directions with respect to a vertical direction. Therefore, when moving the lower arm in the vertical direction, influence of the weight of the lower arm is canceled by the weight of the upper arm, and a force to move the lower arm upward can be reduced. As the result, an air cylinder (63) for changing a distance between the upper arm and the lower arm can be downsized.

A dispenser for dispensing paper toweling. The dispenser including a towel support that is positionable in a first dispensing position when a drive roller rotates in a first direction, and that is positionable in a second auto-loading position when the drive roller rotates in a second direction. Rotation of the drive roller in the first and second directions automatically loading the paper toweling for subsequent dispense.

An optical data storage device includes an optical storage tape having one or more optical storage layers. A plurality of optical pickup units reads and/or writes data to the optical storage tape. A feed reel provides the optical storage tape to the optical pickup units. A guiding wheel that guides the optical storage tape when the optical storage tape is in the vicinity of the optical pickup units during read and/or write operations. Finally, a take-up reel receives the optical storage tape from the guiding wheel.

The device (100) is destined to receive flanked continuous strips (1, 2) from an arrival line (L), and feed them towards a transversal cutting station (SR). The device (100) comprises: a basin (3), associated to a terminal part of the arrival line (L), destined to enable formation, in each of the strips (1, 2) of a free loop (A1, A2) in a downwards direction; deviator organs (4), at a 45° angle, provided downstream of the basin (3), destined to guide the strips (1, 2) such as to orientate them perpendicularly to the arrival direction, horizontally centered and correctly staggered in height such as to enter the transversal cutting station (SR).

A flexible and continuous substrates-conveying sheet has a plurality of to be processed substrates disposed on or in it. A nondestructive transferring unit includes a plurality of first transferring rolls and a plurality of second transferring rolls. The first transferring rolls make contact with a first surface of the substrates-conveying sheet where that surface can have electrostatically-induced charge formed thereon. Each of the first transferring rolls includes a first central portion charged with a positive electric charge and a first outer portion surrounding the first central portion. The second transferring rolls make contact with the first surface of the substrates-conveying sheet. The second transferring rolls are disposed alternately with the first transferring rolls. Each of the second transferring rolls includes a second central portion charged with a negative electric charge and a second outer portion surrounding the second central portion.

In a web printer, tension on the moving web is controlled by monitoring the tension on the web between two rollers and selectively operating an actuator driving the second roller to restore the tension to an acceptable range. The operation of the actuator includes modulating the speed at which the second roller is driven.