Abstract: The specification discloses a vehicle electrical control system capable of switching the alternator output between a uniform standard voltage and a uniform higher voltage. The control system includes a supplemental voltage regulator and a switching circuit for selectively switching the supplemental regulator into the system to regulate the conventional voltage regulator. Preferably, the control system further includes a timing circuit for powering a plurality of electrically heated windows in a timed sequence.

Abstract: This specification teaches a method of making an electrically heated, glass vision unit having a complex curved configuration. The method is initiated by cutting a glass substrate (10) from a flat glass bracket (12). The glass substrate (10) has first and second surfaces separated by a uniform distance. A pair of electrically conductive bus bars (16--16) are applied to one of the surfaces of the glass substrate (10). The bus bars (16--16) are so positioned on the flat glass substrate (10) that when the substrate (10) is bent to form the glass vision unit of complex curved configuration, the pair of electrically conductive bus bars (16--16) are equally distant from one another throughout their entire extent. The flat glass substrate (10) is bent to form the glass vision unit of complex curved configuration. A conductive coating (20) is applied to the one surface of the glass substrate (10) and extends between the pair of bus bars (16--16) throughout their entire extent.

Abstract: A window panel for an unpressurized aircraft has an outer glass sheet and an inner sheet of plastics material. A peripheral adhesive band is adhered to the exposed face of the inner sheet and has an adhesive face of a thermoplastic material for adhesion to a window frame. An electrical heater is embedded in the peripheral band close to its adhesive face.

Abstract: A laminated window for a vehicle, for example a windshield, has electrical conductors carried between the plastics interlayer and one of the glass sheets. An obscuration band is fired on to the margin of the inner surface of the outer glass sheet, which obscures from external view conductive strips near the edges of the window.

Abstract: An automatic device for actuation of components for cleaning motor vehicle glass which includes a system for detection of the dirtiness of the glass, made up of a measuring photosensitive element receiving light directly through the glass and a reference photosensitive element isolated from any direct light and influenced only by the light transmitted through the interior of the glassing and an electronic circuit to receive and compare the responses of the two photosensitive elements and means to control the cleaning components automatically when the difference is response of these elements exceeds a certain threshold.

Abstract: In a fog detecting apparatus with optoelectronic system, comprising infrared-emitting means and infrared-receiving means, is provided means for adjusting a reference which is compared with a voltage value of a detecting signal generated according to an electrical signal produced by the infrared-receiving means in order to distinguish whether a windshield of a vehicle is in the fogging condition or not. The reference is changed according to the detecting signal which is produced when the windshield is in good condition against the fogging after a fog removing apparatus has been actuated to remove the fog attached on the windshield, so that the fogging condition is detected in accuracy independently of the contamination of the optoelectronic system or the like.

Abstract: A process for improving the solderability of a layer of a silver frit burnt onto a glass pane and a current connecting element wherein a layer of enamel is disposed and the surface of soldering and the glass pane. According to the process the surface is treated with a fluorine containing etching agent prior to soldering. The fluorine containing etching agent may be an aqueous solution of an acid fluoride, such as ammonium hydrogen fluoride or alkali hydrogen fluoride.

Abstract: An automotive window glass antenna incorporating in a window glass a first antenna possessing a horizontal part and a vertical part to form a T-shape, a second antenna for phase compensation comprising at least one horizontal antenna wire disposed on one side of the vertical part of the first antenna and connected thereto, a third antenna for impedance matching disposed on the other side of the vertical part of the first antenna and connected thereto, and a feed point connected to the third antenna, said the second and the third antennas being asymmetric with respect to the vertical part of the first antenna.

Abstract: A heated windshield wiper assembly adapted to be secured to the wiper arm of a motor vehicle. The wiper assembly provides intermittent heat to the wiper blade according to weather conditions to prevent icing of the wiper blade and assembly. The wiper assembly generally comprises a conventional wiper blade supported by a structure having a heating element disposed therein. The heating element is connected to the vehicle power source and can be actuated either manually or automatically. During automatic actuation, the heating element is controlled by a thermostat, which senses the ambient air temperature, and a thermocoupler, which senses the temperature of the heating element and wiper blade.

Abstract: A braided, composite lead-in conduit for use in conducting electricity to electroconductive heating means of a heated, multiple-glazed window has spaces between individual wires filled with a substantially moisture impervious material to minimize mositure-vapor penetration into the insulating air space of the window.

Abstract: A device for use in a helmet having a shield panel for preventing the shield panel from fogging by electric heating. A transparent electroconductive film is provided inside the shield panel for passing current through the film to generate heat. An assembly including the conductive film is removable from the shield panel for repeated use when the shield panel is to be replaced by a new one due to damage.

Abstract: The invention relates to a pane coated with a metal oxide coating, particularly a pane for an automobile window.The inventive pane bears a coating on its face intended to be disposed on the interior of the vehicle, which coating is comprised of a metal oxide of low emissivity.Such a pane improves the physiological comfort of the passengers, particularly during cold periods.

Abstract: A circuit and method for interrupting power applied to an electrically conductive panel such as a vehicle windshield or window upon cracking of the conductive coating or element thereon. The circuit includes structure for (1) monitoring the resistance of the conductive element and (2) interrupting power applied thereto when the resistance of the conductive element assumes a value indicative of element cracking.

Abstract: A safety switch for a glass door, which is used for refrigerating and deep freeze chambers and comprises two or more glass panes of hardened glass, of which the front pane (21) remote from the refrigerating and deep freeze chamber is heated by an electrically conductive layer attached on the inner surface of the pane, which layer is connected to an upper and, respectively, lower collecting conductor, and the rear pane (22) facing to the refrigerating and deep freeze chamber is provided with at least one conductor attached on the pane. The conductors are connected to a current scanning device (20), which is capable to scan whether current flows through said collecting conductors and the conductor of the rear pane, and which is capable to break the connection between the conductors of the two panes (21,22) and a voltage source (46) in the event that current does not flow in the collecting conductors and/or in the conductor of the rear pane.

Abstract: A timer circuit suitable for operating, for a required period of time, the windshield defrosting heater in an automobile, comprises a switch operative only in one direction, such as a momentary unidirection switch, a timer which starts timing operation after a lapse of a predetermined time, and a flip-flop circuit or the like. The switch allows setting and cancelling for timing operation, whereby the operative characteristics are improved and the mechanical design is simplified. Moreover, the use of a flip-flop circuit reduces the occurrence of chattering.

Abstract: An improved hand-held flat conductor applying apparatus for applying to the receiving surface of a glass pane such as the rear window in a motor vehicle, a plurality of equidistant essentially straight lengths of pre-glued flat conductor for defining the heating lines of a rear window resistive defroster. The apparatus uses a confining guide edge of predetermined configuration for setting a datum or base line for the heating lines, a translation carrier mounted to the confining guide edge and confined thereto except for translation therealong, a rigid bar secured to the translation carrier through a suitable pivotable foot and locking means therefore, and a conductor laying head supported to the rigid bar and positioned at anyone of a plurality of predetermined points along the rigid bar.

Abstract: A defroster system for a motor vehicle is disclosed having air discharge openings in the dashboard which enable warm air to flow upwardly and impinge against the windshield. To ensure that the lower portion of the windshield is also being heated, and to prevent the windshield wipers from becoming frozen onto the windshield, secondary air ducts are provided which extend from the defroster duct into an open space which is disposed inside the vehicle in the proximity of the lower edge of the windshield and ahead of the windshield. The secondary air ducts are created by depressions formed into the lower wall of the defroster duct.

Abstract: An electrically heated windshield of generally trapezoidal shape has been bus bars of uniform conductivity throughout their length extending in line contact with the upper and lower edges of a continuous uniformly thick trapezoidal-shaped electrically conductive coating provided on the windshield surface for deicing and defrosting the windshield. The line of contact of the upper bus bar with the conductive coating has a length generally equal to the entire effective length of the upper edge of the conductive coating. The lower bus bar is symetrically located along the lower edge of the conductive coating and has a line of contact length equal to the sum of the length of the upper bus bar plus generally about one-half the difference between the entire effective length of the lower edge of the conductive coating minus the length of the line of contact of the upper bus bar.

Abstract: An electric current feeding to an electric heating unit designed for dissipating a fog formed on a glass window of a vehicle by its thermal effect. The apparatus has one fuse connected with an ignition switch and two fuses connected with input terminals of an electromagnetic relay having two contacts for connection with a heating unit in parallel. The electromagnetic relay is actuated by the ignition switch through an electric timer activated by a manual defogger switch. An electric current feeding system is provided for protecting the contacts of the electromagnetic relay from a short-circuit by melting or breakage by arranging the same such that the manual defogger switch, timer and relay are connected with the vehicle power source through one of the three fuses, respectively. Thereby the apparatus can be rendered entirely inoperative when any one of three fuses is blown, or the circuit connected therewith is disconnected.

Abstract: A heater arrangement for an automotive vehicle includes a switching arrangement having a conventional control device which is fed signals from sensors sensing the temperature outside of the vehicle, the temperature inside the vehicle, the temperature of the engine coolant, and the speed of the vehicle. A pulse sequence is generated for controlling a valve which in turn controls the flow of a heating medium to the heating system for heating the passenger compartment of the vehicle, the duration of the pulses in the sequence being varied in accordance with respective conditions. A frequency changer, timer and switch are disposed between an inverter and relay for concomitantly controlling an electric auxiliary heater on the vehicle, such as an electric rear window heater. The switching arrangement provides for switching of the auxiliary heater in conjunction with the switching of the control device for the heating system for the passenger compartment.

Abstract: An electrically heatable self-defrosting windshield has a transparent panel, two low-resistance groups of wires embedded in the panel and defining a primary zone requiring rapid heating, and at least one high-resistance group of wires embedded in the panel and defining a secondary zone adjacent the primary zone and not requiring rapid heating. A switch connected to the wire groups and to an electric power source is movable between a fast-heat position connecting the two low-resistance groups in parallel with each other across the source and effectively disconnecting the high-resistance wires, and a slow-heat position connecting the two low-resistance groups in series with each other and jointly in parallel with the high-resistance groups across the source. The total resistance of the groups in the fast-heat position is generally the same as in the slow-heat position.

Abstract: A control system for regulating the operation of an electric resistance heating grid for de-icing or de-fogging a window of an automobile in accordance with the temperature of the window includes a manually operable switching relay closed by the driver to start the flow of current through the heating grid upon the accumulation of an unacceptable amount of ice or fog on the window. A holding circuit maintains the switching relay closed until such time as an electric resistance-type temperature sensor in heat exchange relationship to the window surface on which the ice or fog accumulates operates through a transistorized circuit to break the holding circuit when the window reaches a preselected temperature high enough to dissipate any fog or ice accumulated thereon.

Abstract: A heater assembly for heating a surface such as the rear window of an automobile. A plurality of heater elements are adhesively secured onto the surface in generally vertically spaced horizontally extending direction. A pair of busbars are adhesively secured onto said surface in generally vertically extending direction overlying the heater elements adjacent the opposite ends thereof. End portions of the heater elements which extend beyond the busbars are wrapped around the busbars and firmly retained by a pair of covering members which are secured in juxtaposed relation to the busbars for providing good electrical contact between the heater elements and the busbars.

Abstract: Electrodes (18) are positioned in intimate contact with an outer surface of a thin electrically-insulating protecting layer (16) of architectural reflective glass (20). Application of a voltage of sufficient magnitude substantially destroys the insulating layer (16) located beneath the electrodes (18). A subsequent application of voltage results in a passage of current through the underlying thin, light-reflective metal or metal oxide layer (14) and in concomitant output of heat.

Abstract: Window panes are provided with electrically conductive wires. At the desired small diameter of less than 50 micrometers the wires which have been used so far have too high a resistance per unit length.The invention provides a sufficiently strong, thin electrically conducting wire having an electric resistivity from 2.0-5.0.mu. .OMEGA. cm.

Abstract: An electrically heated glass pane includes a plurality of heating conductors (2) comprising a family of parallel conductors extending between a pair of power supply conductors (3) both disposed on and burnt-in a surface of a glass pane (1). A strip (4), of non-conductive material, covers conductors (3) and extends laterally from the edges of the conductors. The conductors (2) merge into the conductors (3) at a transitional region (7) broadened by an increasing flare so that the cross section of the region, determining the electrical resistance, is greater than the cross section of the conductors (2) providing resistive heating. A layer (12) which covers the same area as the strip (4) may be disposed below each conductor (3), directly on the surface of the glass pane (1). An opening (16) is recessed in layer (12), so that the conductors (3) are connected directly with the surface of glass pane (1).

Abstract: An electric heater plate is disclosed which is formed on one surface of a base material. A plurality of thin lines of a nonprecious material which acts as a resistor when electrical energy flows therethrough is bonded to the first surface of the base material and extends from a first location thereon to a second location thereon. At least two interconnection areas of a non-precious metal which acts as a resistor when electrical energy flows therethrough are provided. These interconnection areas are bonded to the first surface of the base material with one interconnection area interconnecting the plurality of thin lines at the first location and the second of the interconnection areas interconnecting the plurality of thin lines at the second location on the first surface of the base material. A termination area of silver ceramic material is associated with each of the interconnection areas. Each of the terminal areas is in contact with an associated interconnection area.

Abstract: An electrically heated window is disclosed which achieves a more uniform current density at the interface between the resistive heating layer and the current-bearing electrodes to which it is connected. In one embodiment this may be achieved by forming the edge of the electrode in an undulating shape. It may also be done by increasing the surface resistance of the electrode near its edge by, for example, forming the edge so that it is wedge-shaped in cross-section. More uniform current density may also be achieved by using an electrode which has a resistivity that is greater than that of the resistive heating layer. It may also be achieved by use of a high resistivity layer located between the electrode and the resistive heating layer.

Abstract: A glass antenna system for an automobile comprises a main antenna disposed at an upper part of a glass plate for a rear window of the automobile and a defogging electric heating element disposed below and separate from the main antenna and comprising a plurality of heating strips and a pair of bus bars for supplying electricity to the heating strips. The glass antenna system is characterized in that a lead wire is connected to a predetermined portion of the lower most heating strip among said heating strips and a feeding point for connection to an antenna feeder line is provided on the lead wire, whereby the defogging electric heating element constitutes a subsidiary antenna having a directivity different from the directivity of the main antenna.

Abstract: An electrical resistance heater controller is provided with a plurality of circuit branches connected in parallel with each other and in series with a heating element and an external AC power source. Each circuit branch includes the series connection of a capacitor and a solid state switch. The switches are controlled by a gating device to switch during the zero crossing of the AC source voltage waveform. Power delivered to the heating element is controlled by varying the amount of series capacitance in the circuit.

Abstract: A heated defrosting glass pane contains an alternation of conductive or nonelectricity-conductive regions. The conductive regions are transparent while in a heated state and are arranged in such a manner that during defrosting, they alone, by themselves, provide a sufficient integral visibility through the glass pane, while at the same time the nonconductive zones remain opaque. The ratio of the integral surface between the conductive and nonconductive surfaces is 1/8 to 1/2.

Abstract: A window formed by a glass pane for use as a window for a vehicle. The window is supported by structure carried by the body of the vehicle to move about an axis thereby to swivel between positions of opened and closed. The window supports an electric consumer and electrical conducting strips are carried by the window for use in connecting the electric consumer to a source of power supplied by the vehicle.

Abstract: An economical mirror unit adapted for exterior mounting on an automobile has a single self-regulating electrical resistance heater disc of a material of positive temperature coefficient of resistivity mounted in a recess on a heat-distributing metal plate and enclosed in the recess by a glass reflecting member mounted over the recess so that the heater serves to defog the reflecting surface of the member. Various portions of the plate have selected different spacings from the glass reflecting member for heating various overlying portions of the reflecting member to a substantially uniform temperature so that the heater is operable at a high temperature to rapidly and uniformly defog the mirror without risk of damage to the glass reflecting member.

Abstract: Apparatus for an electrically moved sliding window, used illustratively in automotive applications, having first, a built-in safety device, for providing a signal whenever the window has been raised or lowered to a preselected height and second, a proximity detector is described. The device and detector comprise a plurality of conductors, bonded to the surface of the window. These conductors are, in turn, connected to an integrated circuit element which is also mounted to the surface of the window. This circuit element controls a power stage which, in turn, supplies power to the drive motor which raises and lowers the window. The circuit element and the conductors are placed directly on the window in a stationary position with respect to one another.

Abstract: A flexible device which can be detachably mounted on a window, such as a vehicle window, in order to prevent icing or fogging. The device is a semi-flexible sheet of layered materials having a length and width substantially coterminus with the window and having arranged at intervals along its two dimensions, holders which are used to detachably mount the device on the window. The sheet materials include a rather stiff supporting layer which acts as a backing surface of the sheet and a heat reflecting layer on the sheet side which faces the window when mounted. Optional layers include an insulating layer, a decorative layer, a silicone rubber electrically conductive layer and braided copper electrode strips for connecting the conductive layer to an electric source and causing the generation of heat from the conductive layer. The holders are of a length which will position the sheet a distance of about 5 to 15 mm away from the window.

Abstract: A novel solderless connection between a bus bar and an array of electroconductive wires avoids cracks in plastic window elements, particularly the outer component of curved lightweight heated windows, particularly those used in aircraft.

Abstract: A heating glass plate (15, 20, 27, 34) has a heating network (17, 24, 31, 36) made up of wires embedded in a thermoplastic layer following curved directrices. A device for making a heating glass plate having a plate (39) for supporting thereon a plastic sheet. A bridge (44) is slidably supported on the plate and has thereon a sliding carriage (45) carrying wire-laying members (46). Means are provided for imparting reciprocal motion to the carriage. A rod (51) connects the carriage to a vertical spindle (52).

Abstract: An electrically heated backlite is formed on a glass sheet An opaque, electrically nonconductive coating is bonded to at least two portions of the glass sheet which are spaced apart from one another. Each portion of the nonconductive coating has at least one open area therein. An electrical resistance heater line having spaced terminal ends extends from one portion of the nonconductive coating to the other portion of the nonconductive coating. Each one of the terminal ends of the heater line is overlying and bonded to at least a part of one of the portions of the electrically nonconductive coating and also overlying and bonded to all of the surface of the glass sheet exposed in the open area formed in the portions of the nonconductive coating. An electrical conductor is bonded to the terminal end of the heater line at a location where the terminal end overlies the surface of the glass sheet exposed in the open area of the nonconductive coating in order to increase the bond strength.

Abstract: An electrically heated window is disclosed which achieves a more uniform current density at the interface between the resistive heating layer and the current-bearing electrodes to which it is connected. In one embodiment this may be achieved by forming the edge of the electrode in an undulating shape. It may also be done by increasing the surface resistance of the electrode near its edge by, for example, forming the edge so that it is wedge-shaped in cross-section. More uniform current density may also be achieved by using an electrode which has a resistivity that is greater than that of the resitive heating layer. It may also be achieved by use of a high resistivity layer located between the electrode and the resistive heating layer.

Abstract: In a substantially transparent insulating structure, positionable between a warmer region and a colder region, the improvement comprising an infrared reflecting visible light transmitting coating, applied to a surface of a pane in the structure. The coating reflects a substantial portion of infrared radiation incident thereon, so as to restrict substantial transmission of infrared radiation from the warmer region to the colder region. The reflected infrared radiation heats the surface exposed in use to the warmer region sufficiently to inhibit formation of a visibility-impeding layer thereon, without using electrical energy therefor. The reflected infrared radiation is reradiated into the warmer region, thereby inhibiting reradiation of such reflected infrared radiation into the colder region. The coating further transmits a substantial portion of visible light radiation incident thereon, to enable substantially clear visibility therethrough.

Abstract: A windshield for automotive vehicles is disclosed wherein one or more scraping edges are disposed on its external side in the area wiped by the wiper blades. The scraping edges are an enamel-type material which is formed into strip-shaped profiles and bonded in in raised form to the surface of the glass plate. Varying amounts of metal particles may be added to the enamel material to make it conductive, and, when connected to the vehicle's electrical system, able to thaw ice and snow which accumulates on the lower part of the windshield immobilizing the wiper blade arm. The scraping edges or profiles are positioned at appropriate angles on the windshield to permit water scraped from the windshield wiper blades to run off easily to both sides.

Abstract: The windshield for a motor vehicle is characterized by a transparent panel having a lower region normally outside the driver's field of vision and where at least one windshield wiper is located in the rest position of the wiper. An electric resistance heating element, formed either as a continuous layer or as a plurality of individual conductors connected in parallel by bus bars, is carried on the windshield only in the lower region for heating the area on which the wipers rest. A continuous layer of a heat radiation absorbing ceramic material opaque to ambient light and coextensive with the area of the heating element is disposed on the windshield between the heating element and the windshield wiper to shield the heating element from view from the front of the windshield and to uniformly distribute heat over the lower portion of the windshield. The windshield is a laminate including inner and outer glass panes with a plastic layer therebetween.

Abstract: A portable frost and snow removing appliance for use in removing ice and snow from the surfaces of vehicle windows includes an elongated housing having a pistol handgrip at one end and containing an electrically operated two-speed blower and a resistance heater arranged to produce a high speed jet of unheated air or a slower stream of heated air through a discharge nozzle shiftably mounted on the other end of the housing and movable between first and second positions. The housing includes a lateral air outlet in a side wall between the heater and nozzle. The nozzle includes as a unitary one-piece structure therewith valve members within the housing and nozzle and cooperatively associated with the housing other end and the lateral air outlet to inversely open and close the lateral outlet and housing other end in response to shifting of the nozzle to its first and second positions, respectively, to permit air to be selectively discharged from either the nozzle or lateral air outlet.

Abstract: A method of fabricating very fine metal screens for use in a transparent or translucent panel through which visible light is transmittable but which acts as a barrier against transmissions of pulsed electromagnetic radiation which may be harmful to humans or disruptive to electronic gear. The screens are fabricated by printing a pattern photographically upon a first surface of a metal foil covered on both sides by a positive, photo sensitive etchant mask and removing exposed areas of the mask with a developer. The masked foil is then chemically blanked by application of an etchant to the first side only of the foil. The specimen is rotated 90 degrees on a frequent basis to prevent selective etching, especially in areas adjacent the periphery of the screen.

Abstract: An electroconductive laminated window having an electroconductive coating applied to one interior substrate surface with a pair of bus bars electrically connecting a source of electrical potential thereto. The bus bars include an electroconductive layer having volume resistivity less than about 10.sup.-2 ohm-cm interposed between and conformable to the surface configurations of the electroconductive coating and a flexible metallic current carrying member. The metallic current carrying member is preferably a mesh of thin copper foil which is substantially bendable in its own plane, and the electroconductive layer is preferably a metallic layer substantially free of non-metallic components, consisting of a mixture of finely divided electroconductive particles and finely divided metal alloy particles having a fusion temperature between about 70.degree. C. and about 150.degree. C.

Abstract: A controller system using high frequency switching by providing a bilateral switch gated on and off at a frequency about ten times the source frequency and the duty cycle determined by pulse width modulation of the high frequency waveform in accordance with window heater temperature.

Abstract: A metallic foil is laminated to a transparent substrate with a photopolymerizable adhesive. An outer layer of photoresist is used in etching a pattern in the foil. The etched foil itself is then used as a resist in the complete removal of the uncovered portions of the adhesive, leaving the transparency of the revealed substrate material totally unimpaired. Finally, the remaining adhesive is hardened by polymerization resulting from exposure to ultraviolet light passed through the substrate from the unlaminated side.

Abstract: A remote transmitter is operative to start an electrical heater disposed in an automobile. The electrical heater operates off a separate electrical system from that normally found in the automobile. Once the automobile engine is started and the heating system of the automobile is operative, a thermostatic switch is actuated which removes power from the electrical heater.

Abstract: An electroconductive laminated window having an electroconductive coating applied to one interior substrate surface with a pair of bus bars electrically connecting a source of electrical potential thereto. The bus bars include an electroconductive layer having volume resistivity less than about 10.sup.-2 ohm-cm interposed between and conformable to the surface configurations of the electroconductive coating and a flexible metallic current carrying member. The metallic current carrying member is preferably a mesh of thin copper foil which is substantially bendable in its own plane, and the electroconductive layer is preferably a metallic layer substantially free of non-metallic components, consisting of a mixture of finely divided electroconductive particles and finely divided metal alloy particles having a fusion temperature between about 70.degree. C. and about 150.degree. C.

Abstract: A windshield for automotive vehicles is disclosed wherein one or more scraping edges are disposed on its external side in the area wiped by the wiper blades. The scraping edges are an enamel-type material which is formed into strip-shaped profiles and bonded in in raised form to the surface of the glass plate. Varying amounts of metal particles may be added to the enamel material to make it conductive, and, when connected to the vehicle's electrical system, able to thaw ice and snow which accumulates on the lower part of the windshield immobilizing the wiper blade arm. The scraping edges or profiles are positioned at appropriate angles on the windshield to permit water scraped from the windshield wiper blades to run off easily to both sides.