A hydraulic control system for a machine is disclosed. The hydraulic control system may have a tank, a pump configured to draw fluid from the tank and pressurize the fluid, an actuator, and a control valve configured to direct fluid from the pump to the actuator and from the actuator to the tank to move the actuator. The hydraulic system may also have a main relief valve movable away from a closed position to pass pressurized fluid to the tank when a pressure of the fluid directed to the actuator exceeds a first threshold pressure, and a controller in communication with the pump. The controller may be configured to selectively reduce a displacement of the pump after the main relief valve has moved away from the closed position when the pressure of the fluid directed to the actuator exceeds a second threshold pressure.

Machines such as excavators, loaders, dozers, motor graders, and other types of heavy equipment use one or more actuators supplied with hydraulic fluid from a pump on the machine to accomplish a variety of tasks. These actuators are typically velocity controlled based on an actuation position of an operator interface device. For example, an operator interface device such as a joystick, a pedal, or another suitable device may be movable to generate a signal indicative of a desired velocity of an associated hydraulic actuator. When an operator moves the interface device, the operator expects the hydraulic actuator to move at an associated predetermined velocity.
In some situations, it may be possible for a pressure of the fluid supplied to the actuator(s) to exceed a desired level. This over-pressure situation can occur, for example, when work tool movement becomes stalled (e.g., when the work tool strikes against an immovable object). In these situations, the actuator or other components of the associated system can malfunction or be damaged. Accordingly, care should be taken to avoid such occurrences.
Conventionally, over-pressure situations are dealt with in one of two different ways. First, a main pressure relief valve associated with the system can open when system pressure exceeds a desired pressure. High-pressure fluid from the system is then dumped through the open valve into a low-pressure tank, thereby reducing the pressure of the system. Although effective, this strategy can be inefficient, as the dumped fluid contains significant energy that is wasted. At the same time, the wasted energy is dissipated in the form of heat, which creates a cooling issue itself. The second way to deal with high-pressure is to implement a pump control strategy known as high-pressure cutout, which automatically reduces pump output upon detection of an over-pressure situation. The reduction in pump output allows for a corresponding reduction in system pressure as the pressurized fluid within the system is consumed. Although also effective, high-pressure cutout can cause a sudden and unexpected drop in power. In addition, high-pressure cutout, by itself, may not be responsive enough to ensure that harmful over-pressure spikes do not occur.
In some situations, a main relief valve may be used together with a high-pressure cutout strategy. Specifically, the pump can be controlled to reduce power as system pressures increase and, when the system pressures further increase and exceed a desired level, a main relief valve can open to protect system components from damaging extremes. This strategy, however, may still cause a drop in power that is unexpected and undesired by the operator.
The disclosed hydraulic control system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.

Hydraulic control system having over-pressure protection


A vacuum cleaner with a separation module comprises an exhaust grill positioned fluidly between a separator chamber and an air outlet. The exhaust grill can comprise a body having a plurality of louvers and a plurality of inlets defined between adjacent louvers.

Upright vacuum cleaners employing cyclone separators are well known. Some cyclone separators use frusto-conical-shaped separators and others use high-speed rotational motion of the air/dirt to separate the dirt by centrifugal force. Typically, working air enters and exits at an upper portion of the cyclone separator as the bottom portion of the cyclone separator is used to collect debris. Before exiting the cyclone separator, the working air may flow through an exhaust grill. The exhaust grill can have perforations or holes through which air may pass, or may have vanes or louvers defining openings through which air may pass.

Vacuum cleaner with louvered exhaust grill


A method for controlling an air supply of a fuel cell vehicle is provided. In particular, an air supply of a fuel cell vehicle is controlled by calculating an available power which is currently being used by a vehicle; calculating a motoring request power from a driving motor, based on the calculated available power and power required by the driving motor; calculating stack request power required in the fuel cell based on a required charging request power and the calculated motoring request power, depending on a state of charge (SOC) of a high voltage battery; and controlling the air supply to the fuel cell depending on the calculated stack request power.

1. Technical Field
The present invention relates to a system and method for controlling an air supply of a fuel cell vehicle, and more particularly, to a method for controlling an air supply of a fuel cell vehicle capable of improving fuel efficiency by calculating the actual amount of air supply required, based on available power which may be currently used in a vehicle.
2. Description of the Related Art
A fuel cell vehicle includes a fuel cell stack in which a plurality of fuel cells used as a power source are stacked sequentially, a fuel supply system configured to supply hydrogen, and the like, as a fuel to the fuel cell stack, an air supply system configured to supply oxygen as an oxidizing agent required for electrochemical reaction, and a water and heat management system configured to control a temperature of the fuel cell stack, and the like.
In particular, the fuel supply system decompresses compressed hydrogen within a hydrogen tank to supply the decompressed hydrogen to an anode of the stack and the air supply system actuates an air blower to supply external air to a cathode of the stack.
When hydrogen is supplied to the anode of the stack and oxygen is supplied to the cathode, hydrogen ions are separated by catalytic reaction in the anode. The separated hydrogen ions are delivered to a negative electrode, (i.e., the cathode), through an electrolyte membrane and the hydrogen ions and electrodes separated in the anode electrochemically react with oxygen in the negative electrode, thereby obtaining electric energy.
A portion of the electric energy generated in the fuel cell stack may be used as a power source of a driving motor through an inverter and may be used to charge a high voltage battery through a converter.
When positions of an accelerator pedal, a braking pedal, a gear, and the like are input to a controller, the controller may issue a command to a motor control unit to control a driving motor, in which the motor control unit controls a speed and a torque of the driving motor accordingly.
Typically, an air supply control of the fuel cell vehicle is performed by calculating a torque for a driver's acceleration request based on power. In this case, an air supply quantity larger than the currently available power is required, which may lead to reductions in fuel efficiency and performance.

System and method for controlling air supply of fuel cell vehicle


Braided or twisted lines made from a) gel spun polyolefin yarns and b) at least one other yarn or monofilament are stretched to increase line tenacity. If desired, stretching conditions can also be chosen to significantly reduce the denier of the line.

Fishing lines based on ultrahigh molecular weight, high tenacity, polyolefin yarns represented a dramatic shift in the technology of fishing lines. The filaments and their manufacturing process are described in Kavesh et al. U.S. Pat. No. 4,413,110; Smith et al. U.S. Pat. No. 4,344,908; Smith et al. 4,422,993; Kavesh et al. U.S. Pat. No. 4,356,138; Maurer E. P. 55,001; Harpell et al. U.S. Pat. No. 4,455,273; Kavesh et al, U.S. Pat. No. 4,897,902; Neal U.S. Pat. No. 5,277,858; and Kirkland et al. WO 94/00627. In general, the filaments are made by spinning from a gel solution containing the polymer in a solvent. As the solvent is removed from the spun filament, the filament is stretched to form a high strength, high tenacity filament of high molecular weight. Filaments made from linear polyethylene or polypropylene exhibit a molecular weight of at least 400,000, a tenacity of at least 15 g/denier, a tensile modulus of at least 500 g/denier, a melting point of at least 140° C.
Once bundled into yarns, a plurality of yarns can be made into an excellent fishing line. Processes for doing so are described in Cook U.S. Pat. Nos. 5,749,214; 5,540,990 and 6,148,597. The process described in these patents generally teach a re-stretching or "re-drawing" process under suitable heat and tension to cause the fishing line to lengthen with an increase in tenacity.
Another process is described in Cunningham et al. U.S. Pat. No. 5,573,850 which discloses a yarn having a polyethylene core that is then sheathed in a heated polymeric coating. The result of this process is described as providing monofilament-like characteristics to a multifilament construction.
The disclosures of each of these patents are herein incorporated by reference.
The high tenacity and low degree of stretch while submerged in water has made such fishing lines an important tool for anglers of all skill levels. Despite their technological prowess for many aspects of fishing, however, lines made from ultrahigh molecular weight, high tenacity polyolefin yarns have one shortcoming for some anglers: the lines float. With a specific gravity of only 0.97, some fishing techniques require that the fishing line have a negative buoyancy to get the lure at the right depth with the right action at that depth.
The use of weights added to the terminal end of the line do not satisfactorily address the issues associated with a floating line. For example, floating lines tend to pull a trolled lure to the water's surface thereby requiring additional weight to pull the lure back down. This combination of factors postures the lure in an upward orientation or with a more sharply sloping angle to the trailing line than would be desired. Floating lines may also disrupt or prevent a fishing technique that relies on a nonmoving lure that might stimulate a stunned prey.
It would be desirable to have a fishing line with the high tenacity and low stretch properties that are characteristic of fishing lines made with ultrahigh molecular weight, high tenacity, polyolefin yarns but with an overall specific gravity of greater than 1.0 so that the fishing line has negative buoyancy apart from any added weight, terminal connector or lure. This is not as easy as one might think.
A fishing line should have a relatively smooth exterior surface along its entire length. Such smoothness dramatically affects the drag resistance characteristics of the fishing line so surface bumps, ridges and protrusions above the line surface are defects that should be avoided to make a desirable fishing line. Thus, any composite of fishing line yarns must consider the yarn accumulation process, e.g., braiding, twisting or nonwoven formation, as well as the processing temperature, duration, draw rate (if any), number of draw stations and the chemistries associated with any processing aids, lubricants, coatings or the like that are used during the manufacturing process. All of the materials used in any composite must act in substantially the same way, despite any differences in chemistry, to minimize or avoid surface protrusions immediately following manufacture as well as up to months after manufacture despite a wide variety of packaging, shipping and storage conditions and extremes.
It would further be desirable to have a sinking, composite fishing line that would have a minimum of surface defects despite extended storage conditions and environmental extremes.


An electromagnetic connecting device includes a flange of a hub, an armature supported by the flange via a leaf spring, a rotor accommodating an electromagnetic coil, and an anti-vibration member. When an electric current is supplied to the electromagnetic coil, the armature moves in the axial direction of the hub against the spring force of the leaf spring, and is attracted to the rotor. The leaf spring includes a moving portion that moves in the axial direction together with the movement of the armature. The anti-vibration member is fixed to the moving portion of the leaf spring. The anti-vibration member includes a stopper that comes in contact with the flange, and a damper that comes in contact with the armature. With this configuration, an electromagnetic connecting device capable of reducing an impact sound both when the armature is attracted and released can be manufactured at a low manufacturing cost.

The present invention relates to an electromagnetic connecting device including an anti-vibration member that reduces an impact sound generated when an armature is magnetically attracted or released.
An example of an electromagnetic connecting device having a device that reduces an impact sound in operation is an electromagnetic clutch disclosed in Japanese Patent Laid-Open No. 6-10973 (literature 1). This electromagnetic clutch includes an anti-vibration member that reduces an impact sound when an armature is magnetically attracted to a rotor, and a cushion member that reduces an impact sound when the armature is returned to a release position by the spring force of a leaf spring.
This electromagnetic clutch includes two types of members, i.e., the anti-vibration member and the cushion member, in order to reduce the impact sound both when the armature is magnetically attracted to the rotor and when the armature is released from it. Therefore, this electromagnetic clutch has the problem that the manufacturing cost increases because the number of parts increases.
This problem similarly arises when the anti-vibration member and the cushion member disclosed in literature 1 are applied to an electromagnetic brake. In this case, the armature disclosed in literature 1 is electromagnetically attracted to a fixed stator (field core), instead of the rotor.


An object of the present invention is to provide a method for producing a gallium nitride-based compound semiconductor multilayer structure useful for the production of a gallium nitride-based compound semiconductor light-emitting device which can ensure that the operating voltage is reduced, the light emission output is good and the light emission output is less changed due to aging.

In recent years, gallium nitride-based compound semiconductors have become of interest as materials for producing a light-emitting device which emits light of a short wavelength. Generally, a gallium nitride-based compound semiconductor is grown on a substrate made of an oxide crystal such as a sapphire single crystal, a silicon carbide single crystal, or a Group III-V compound single crystal, through a method such as metal-organic chemical vapor deposition (MOCVD), molecular-beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE).
At present, the crystal growth method that is most widely employed in the industry includes growing a semiconductor crystal on a substrate such as sapphire, SiC, GaN, or AlN, through metal-organic chemical vapor deposition (MOCVD). Specifically, an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer are grown on the aforementioned substrate, in a reactor tube, by use of a Group III organometallic compound and a Group V source gas and at a temperature of about 700° C. to about 1,200° C. After the growth of the above layers, a negative electrode is formed on the substrate or the n-type semiconductor layer, and a positive electrode is formed on the p-type semiconductor layer, whereby a light-emitting device is fabricated.
Conventionally, such a light-emitting layer is formed from InGaN whose composition is controlled so as to adjust the light emission wavelength. The active layer is sandwiched by layers having a bandgap higher than that of InGaN, thereby forming a double-hetero structure, or is incorporated into a multiple quantum well structure on the basis of the quantum well effect.
In a gallium nitride-based compound semiconductor light-emitting device having a light-emitting layer of a multiple quantum well structure, when the thickness of a well layer is adjusted to 2 to 3 nm, satisfactory output is attained, but a problematically high operating voltage is required. In contrast, when the thickness of the well layer is 2 nm or less, the operating voltage is lowered, but the satisfactory output, i.e., high-efficiency light emission, cannot be attained.
U.S. Patent Application Publication US2003/0160229A1 has proposed a gallium nitride-based compound semiconductor light-emitting device comprising a light-emitting layer having a multiple quantum well structure, where a thickness variation is imparted to the active well layer so as to obtain high-efficiency light emission.
Also, Japanese Patent No. 3,660,446 discloses a nitride semiconductor light-emitting device having a quantum well structure where the well layer has a non-uniform thickness. According to this patent publication, in the active layer of the quantum well structure, a very thin nitride semiconductor layer or a metal layer, having in-plane thickness distribution and in-plane crystallinity distribution, is provided below a well layer and the well layer is grown thereon, whereby the well layer is selectively grown, the active layer becomes a quantum dot, the light emission efficiency is greatly enhanced, and a highly reliable nitride semiconductor device can be realized. Furthermore, in this patent publication, the device reliability is enhanced by varying the thickness of the layer stacked below the well layer to change the film quality of the well layer.
However, studies by the present inventors have revealed that in a gallium nitride-based compound semiconductor light-emitting device comprising a light-emitting layer having a multiple quantum well structure, when the thickness of the well layer is made non-uniform, the light emission intensity disadvantageously deteriorates due to aging.

Production method of gallium nitride-based compound semiconductor multilayer structure

Abstract: The inventive production method of a gallium nitride-based compound semiconductor multilayer structure comprises a substrate having thereon an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer, the light-emitting layer being disposed between the n-type semiconductor layer and the p-type semiconductor layer, and the light-emitting layer having a multiple quantum well structure formed by alternately stacking a well layer and a barrier layer, wherein at least one well layer has a non-uniform thickness, at least a part of the barrier layer is grown at a higher temperature than the well layer, and the temperature difference between each growth temperature of the well layer, the barrier layer and the p-type semiconductor layer is adjusted to be in a specific range.


A vehicle console center console assembly including a first portion secured to an instrument panel and incorporating a gear shifter and a second portion supported upon a vehicle floor and establishing a mating profile along each of first and second sides with the first portion. Upper located and angled mating shoulders established between the portions limit the effect of sagging of the first portion, via support provided from the second portion. The appearance of gaps in the mating profiles is further limited by overlapping the edges of the second portion to those of the first portion. The second portion further includes inwardly configured support tabs proximate its side edges and which establish channels therebetween for seating the trailing edges of the first portion and permitting a limited degree of non-evident misalignment between the portions.

Center console assemblies typically include a first or forward mounted console portion incorporating a gear shifter mechanism and which is secured, such as by brackets, to the vehicle instrument panel, in turn typically connected to such as a crosswise extending vehicle A-pillar. A rear console portion is in turn supported upon a vehicle floor, typically a ½ tunnel configuration extending in lengthwise fashion between front seats of the vehicle.
In use, the forward console portion tends to sag about its bracket connections to the instrument panel. Given the floor supporting nature of the rear console portion, the creation of gaps between aligning side edges of the forward and rear console portions is an often occurrence in response to pivoting deflection of the forward console relative to the fixed and upwardly force projecting rear console.

Toyota Motor Engineering & Manufacturing North America, Inc.


A strip includes fasteners (1), each having a shank (2) which is pointed at one end (4) and bears a head (3) at the other end. The fasteners are respectively engaged by their shanks (2) in guide and damping blocks joined together in a string (8). The strip further includes a second guide string (9).

In general, for this purpose use is made of indirectly fired anchoring equipment and a fastener is introduced into the barrel either by hand, from the front, into the plug guide of the equipment, or automatically using a loader.
In order that, as it is being driven along the barrel of the equipment, after firing and before being introduced into the receiving material, the fastener remains perfectly coaxial with the barrel, does not tip with respect to the axis and therefore remains correctly guided, it has already been proposed for a guide washer or guide block to be slipped onto the shank of the fastener. In fact, two guide washers spaced apart along the shank or one guide block of sufficient axial length to ensure good cohesion between the nail and its guide block have already been proposed.
It will be noted that feeding fasteners with guide washers into the barrel of the equipment can be performed only by hand, or, at a pinch, from a dispenser, whereas fasteners with guide blocks can be offered up in strip form with their blocks back to back in a string, the strip being mounted in a loader with a return spring so that when the loader is mounted on the equipment, it pushes the strip and introduces a guide block into the barrel prior to each firing. A string of guide blocks is described, for example, in patent EP 0 502 667.
It will also be noted that with fasteners in strip form, after each firing, the block of the fastener that is to be driven is separated from the adjacent block by shearing by the flyweight of the equipment and then, at the moment that the fastener is driven into the receiving material, the block acts as a damper and as a washer.

Strip of fasteners and loader of such a strip for equipment for driving such fasteners

Societe de Prospection et d'Inventions Techniques SPIT


A polishing pad having grooved window therein is provided. The polishing pad comprises a polishing layer and a window, wherein the polishing layer has at least one first groove therein and the window has at least one second groove therein. More particularly, the first groove is deeper than the second groove. The polishing pad having a grooved window therein has advantages of providing precise endpoint detection and thereby reducing or resolving defect problems.

1. Field of the Invention
The present invention generally relates to a polishing pad and a method of forming the same. More particularly, the present invention relates to a polishing pad having grooved window therein and a method of forming the same.
2. Description of Related Art
Endpoint detection techniques have been generally used for chemical-mechanical polishing (CMP) to ensure the polishing quality. Among those techniques, optical endpoint detection through a transparent detection window in a polishing pad provides a reliable result.
U.S. Pat. No. 5,893,796 discloses a method of forming a transparent window in a polishing pad by forming an aperture in a polishing layer first, and then a transparent window is fixed in the aperture with a layer of adhesive. Unfortunately, the slurry solution inevitably permeates through transparent window/polishing layer interface and leaks into the backside of the polishing pad, especially under the influence of the stress during polishing. Meanwhile, this would interfere with the optical signal and therefore the endpoint detection cannot be accurate.
U.S. Pat. No. 6,171,181 discloses a polishing pad with an integral window without above-mentioned slurry solution leakage problem. However, thereafter, during the process of forming grooves on the polishing pad with an integral window, grooves are also formed on the window portion with same groove depth as the grooves formed in the non-window portion. The non-smooth surface of the window portion, with grooves thereon, will lead to less light permeability and get lower reflected optical signal, which will degrade sensitivity of the endpoint detection. Besides, byproducts produced by reaction between polished materials and slurry and the slurry abrasive accumulated in the grooves on the window portion further makes endpoint detection difficult, even when the lifetime of the polishing pad is still within specification.
It is possible to form grooves by using mechanical techniques, such as cutting, only on the non-window portion of the polishing pad by controlling the distance between cutting tool and polishing pad, that is, the cutting tool lifts up only for the widow portion. However, the distance controlling stability for aligning to the window portion is challenging. Furthermore, there are some drawbacks of the polishing pad with no grooves formed on the window portion, firstly, sharp rising step of groove depth from grooved non-window portion to non-grooved widow portion will become a defect source when substrate moves relatively across window portion. Secondly, uneven friction and poor wettability of the window portion relative to non-window portion, due to absence of grooves on the entire window surface, makes the window itself become another defect source.
It would be desirable if a polishing pad having a transparent window therein that normally functions for endpoint detection can be utilized, while at the same time, the defects described above can be reduced or resolved.

Polishing pad having grooved window therein and method of forming the same


An electromagnetic tracking system including a patient support element and an electromagnetic field generator. The patient support element is superposed relative to the electromagnetic field generator, and the electromagnetic field generator is selectively moveable relative to the patient support element.

Minimally invasive, image-guided surgery (IGS) offers potential benefits to surgeons and patients alike by providing improved visualization of a surgical target, critical structures surrounding the surgical target, as well as the positioning of instruments used during the surgery, thereby leading to improved surgical accuracy, patient safety, patient recovery, and clinical outcome. Applications of IGS include a wide spectrum of surgical interventions, such as intracranial, head and neck, orthopaedic, spine, and thoracic surgeries. Among the systems enabling next-generation IGS are intraoperative imaging systems, such as mobile C-arms capable of 3D imaging, and guidance systems that register real-time tracking with intraoperative images.
An integral part of IGS is the tracking system. Well known tracking systems include the Polaris Spectra (Northern Digital (NDI), Waterloo, ON Canada), which is based on a stereoscopic infrared camera and retro-reflective markers attached to tracked tools, and the MicronTracker (Claron Technology Inc., Toronto, ON Canada), which is based on a stereoscopic video camera and checkerboard markers. Such systems demonstrate excellent geometric accuracy (about 0.5-2 mm target registration error (TRE)) but suffer potential limitations associated with line of sight obstruction and the inability to track flexible devices within the body. As a result, such optical trackers are typically limited to externalized, rigid tools, such as, for example, rigid pointers and other devices having handles (and markers) that remain outside the body.
The accuracy required in clinical procedures is strongly dependent on the application and surgical site. For example, a previous geometric model has calculated the allowable translational and rotational errors for safe pedicle screw insertion to range from 0.0 mm/0.0° at the T5 vertebra to 3.8 mm/22.7° at the L5 vertebra. The geometric accuracy of tracking systems achieved in practice is typically about 1.5 mm in association with external, rigid tools, such as, for example, rigid pointers or frames. Electromagnetic (EM) trackers provide increased flexibility in tool design due to the use of a small EM sensor and freedom from line-of-sight obstruction. While EM trackers can exhibit somewhat reduced geometric accuracy (about 1-2 mm TRE for the Aurora EM tracking system, NDI) and susceptibility to EM field distortion in the presence of metallic objects, they permit implementations on flexible internal devices (e.g., a bronchoscope) and have shown clinically acceptable accuracy under optimal conditions. Previous studies have examined the influence of specific application settings and the use of specific surgical tools on tracker position and orientation accuracy.
A conventional EM tracker arrangement places an electromagnetic field generator (EMFG) on a mechanical arm over an operating table. The EMFG is draped in proximity to the sterile field. This setup has also been extended to C-arm cone-beam computed tomography (CBCT) by moving the tracker just outside the C-arm field-of-view (FOV). The EMFG typically includes a mass of metallic coils that are not x-ray compatible, necessitating that it be moved during x-ray imaging or positioned out of the x-ray FOV such that the tracker FOV still encompasses the surgical field.
An exemplary setup of a conventional EMFG mounted at tableside is shown in FIG. 1. The setup is shown within the context of x-ray fluoroscopy and/or CBCT. The region of the patient including the surgical target is placed within the FOV ("measurement volume") of the EM tracker (and the fluoroscopy/CT system). The Aurora EMFG is shown (NDI, Waterloo ON), along with an EM tracker control unit, tracked wired tools, two power cables, and a serial communication cable to personal computer (PC).
This conventional EM tracker arrangement has many limitations. First, arranging essential components of the EM tracking system is time-consuming and makes operating rooms complicated—an EMFG, an EM tracker control unit, wired tracked tools, two power cables, and a serial communication cable to PC must be arranged in an operating site so as to avoid other medical equipment. Second, the complicated setup limits intraoperative use of image-guided surgical system—the cables, tripod, and/or support arm needed to hold the EMFG can be incompatible with X-ray fluoroscopy, computed tomography (CT), and/or CBCT when the EMFG is in place. Thus, the EMFG must generally be positioned outside of the X-ray field. Additionally, the conventional position of the EMFG over the table limits space and access to the patient. Further, mounting of the EMFG above the table on a support arm introduces potential sterility challenges—the system must be bagged and protected from non-sterile exposure.
Accordingly, there is a need in the pertinent art for electromagnetic tracking systems and methods that improve space and access to the patient while preserving the sterility of the surgical field. There is a further need in the pertinent art for electromagnetic tracking systems and methods that are compatible with X-ray imaging techniques, thereby permitting intraoperative usage of such systems and methods.

Electromagnetic tracking system and methods of using same


A cap with adjustable side visors is disclosed having a main body portion conforming to one's head, a rear adjustable strap and a forward extending curved main visor. A pair of spaced side visors are disposed on opposite sides of the main visor extending downwardly therefrom. Each side visor has a flap pivotally mounted thereto which is movable from a first position disposed within the respective side visor to a second position extending downwardly therefrom to vary the shading desired by the user.

1. Field of the Invention
The invention relates to caps; and, more particularly, to caps having shades for blocking the sun.
2. Related Art
Caps are worn by many people, particularly those engaged in sports. Such caps have a strap or the like for adjusting the cap to one's head and a forwardly extending curved main visor, the latter blocking the sun so that the sun's glare won't affect the user's concentration in sports or the like. In some sports, such as golf, it is not easy to adjust one's position when addressing the golf ball. In such cases, the main visor may not be sufficient to block the sun. The golfer may put his or her hand up to the main visor shading the sun on one side or the other of the main visor.
In U.S. Pat. Nos. 4,839,924 and 4,321,709 hats are disclosed having flexible side visors associated with the main visor. In U.S. Pat. No. 5,007,110, a hat is disclosed with rigid side blinders which can be folded inwardly (FIG. 5). In U.S. Pat. No. 5,694,648, side flaps are provided on a hat.
However, although these patents recognize the shading problems with a conventional visored cap, none show added shading means associated with the side flaps for providing more shading on one or both sides of the cap.
There is thus a need for a visored cap having added shading means disposed on each side of the main visor for shading one's eyes from the sun.


An optical sensor consisting of a nearly monochromatic point source such as a light emitting diode (LED) or a vertical cavity surface emitting laser (VCSEL) which is mounted on a multiple element detector. When this sensor is placed near a moving object with a reflective periodic pattern on its surface (such as an optical disk), it can produce a signal which can be used to control the position of the object. Unlike other sensors which often use lenses to project the light emitted by the light source onto the object and collect the light reflected from the object and project them onto a photodector, this new sensor performs the tasks of object illumination and light collection without the use of any optical component. A self-imaging principle is used by placing the detector on the self-imaging plare of the object to detect the motion of the object. In order to detect the periodic signal in the self-image of the periodic object, the detector element is covered with a grating structure having the same period or two times the period of the object.

The present invention relates to an optical track sensing device, and in particular to an optical sensor for detecting optical tracking information on a magnetic floppy disk.
A high density floppy disk drive has been developed to store 120 megabytes of data on a 3.5" floppy disk. This high capacity floppy disk uses a special floppy disk with optical tracks recorded on one of its surfaces to allow the magnetic recording head to store information with closer track spacing. An optical track is recorded between every two magnetic tracks to provide more precise positioning information than can be achieved using the magnetic data alone. This allows the magnetic tracks to be placed closer together. In order to place the magnetic head precisely with respect to the optical tracks, an optical sensing device is used to detect the error between the magnetic head and the optical track. A prior art sensing device was described in a paper by S. W. Farnsworth, S. D. Wilson and B. Cohen entitled "Diffractive Optical System for Tracking on Floptical Disk", Optical Instrument, SPIE Vol. 1690, pp.72-79, 1992.
FIG. 1 shows this prior art track sensing device. A semiconductor laser source 11 is imaged by a lens 13 and a rooftop mirror 14 to the floppy disk 15. A diffractive optical element 12 is used to divide the laser beam into many beams. While some beams are reflected upwards towards the floppy disk, others are reflected downwards ty the lower half of the rooftop mirror to an encoder 16. The encoder provides tracking information to the floppy disk drive when a low density floppy disk without pre-recorded tracks is inserted into the disk drive. The encoder is a strip of optical tracks along the inside housing of the floppy disk crive which allows the position of the magnetic head to be determined optically, even though no optical tracks are on the low density floppy disk itself. The optical sensor is mounted on the magnetic head itself, and a hole is provided through the arm supporting the magnetic head for the optical path. This special optical track sensor permits this high density floppy disk drive to be backward compatible with the low density floppy disks. The returned beams from the floppy disk and the encoder are again reflected by the rooftop mirror 14 and are projected by a lens 17 to a multiple element detector 18.
The detector typically has six elements arranged in two rows. A first row of three elements is used to detect the tracking information from the floppy disk, while the second row is used to detect the encoder on the floppy disk drive housing. A double-slit optical element is used to provide an interference pattern, with the spacing of the interference lobes matching the spacing of the optical tracks. In this way, multiple tracks can be detected at once. Thus, each of the six elements of the detector should see five separate images corresponding to five tracks. The intensity of the received signal will be low, indicating a tracking error, if one or more beams is missing. Thus, the optical sensor splits the laser beam in two, for the floppy disk and the encoder on the housing. Next, each of the two beams are split into three to provide beams which can be detected by the three optical elements in each row of the detector. Finally, each of the six beams is split into five lobes to enable detection of each of five optical tracks.
One of the characteristics of this prior art optical track sensor is that the optical axis of lenss 12 and the optical axis of the lens 17 subtend a small angle with respect to the mechanical axis. Consequently, the laser beams produced by the diffractive optical element 12 are not perpendicular to the surface of the floppy disk or the encoder. As a result, the lateral position of the beams on the floppy disk will change when the floppy disk moves up and down with respect to the image plane of the lens 13. Because of the multiple beams and lobes used, even a small variation in up and down movement of a floppy disk can affect the accuracy of the optical tracking.


A deck of thirty-six playing cards representing every roll combination of two six-sided dice. Each card displays the two dice on the face of each card in different color so as to distinguish every possible combination of the two dice. A corresponding game using this deck of cards for more than one players to achieve a winning suit of four cards of the same numerical total, containing the same dice, or of a specific orientation of high cards or low cards.

This invention relates generally to card games, and more particularly to card games with dice.
Conventional games are played by two types of game players, namely card players and dice players. Typically, skilled card players enjoy cards playing because they possess superior ability to memorize, or "count cards." Since the number of cards in a deck of playing cards is fixed, a card player who can memorize cards removed from the original deck will have the advantage of predicting the next upcoming cards from the remaining card deck by the process of elimination of counting cards.
On the other hand skilled dice players generally masters the calculation of probability. Since each roll of dice is completely separate from a previous or subsequent roll, the probability of each roll is exactly the same (i.e. one in six for a single dice, or one in thirty-six for a pair of dice). One cannot predict the probability of the rolls by eliminating previous rolls because each roll is independent of one another.
Conventional games do not have the special features offered by the combination of card and dice games. Therefore, it is desirable to have a dice game where skilled cards players with superior memory can combine the skill of card playing and counting with the skill of calculating probability of a dice game.
Furthermore, there is a need of a combination card and dice apparatus that may substitute the use of a pair of dice in most conventional games requiring the use of dice to determine probability. During travels on cars and trains, the vibration within the moving compartment frequently makes it difficult to play a game that requires a stable flat surface to throw a pair of dice. Especially in such environment, the throwing of dice is undesirable because dice easily bounces off the surface due to the movement and vibration. Therefore it is highly desirable to substitute dice throwing with cards drawing so that vibrations within such compartment will not affect the probability determination of the game. In addition, the use of cards will eliminate the percussive sound generated by the rolling of the dice on the surface. To some players, the repetitive percussive sound from the repeating roll of the dice is annoying and undesirable. Therefore, the use of cards will be preferable.
Additionally, card players may also elect to not recycle drawn cards back into the card deck, thereby allowing players with superior memory to eliminate those previously drawn cards in their probability calculation. This will provide additional challenge and excitement to allow a player to better predict the subsequent cards being drawn from the remaining card deck.
The general idea of a combination card and dice game is not novel. For e.g., U.S. Pat. No. 4,443,012 by Makovic et al. discloses a card game showing two dices that represent the numerical total of the two dice on each card. This game consists of sixty cards (six of each numerical total) and has no correlation with the probability of the occurrence of the roll of the dice. For example, the numerical total of six contains three combinations, namely, five and one, four and two, and three and three. All three combinations are put onto the same card. This game also requires the use of a pair of real dice, which is cumbersome and lack a major feature of the present invention of substituting the pair of dice completely. In addition, this game does not have the card containing the most common numerical combination of a pair of dice, namely, seven. Therefore the '012 patent does not satisfy the earlier identified needs.
Thus, there is a need for a game combining the skills of calculating the probability of a pair of dice roll and the memorization skills of counting cards to better predict the subsequent cards being drawn. In addition, it will also be highly desirable to have a combination card and dice game that substitute the use of a pair of dice because dice frequently bounce off the play surface during the roll, and eliminate the repetitive percussive noise from a dice roll.

Stack of cards representing a pair of dice and game


A portable nature stand having a seat which can be turned through three hundred and sixty degrees, a platform, and one or more ladder sections connected to and extending downwardly from the platform at an acute angle to the upper surface of the platform.

The present invention relates to a portable nature stand, and more particularly to a stand of the type which can be transported into an area such as a forest having many trees and which can be easily mounted in operative position so as to provide a safe and comfortable vantage point from which to observe nature. Such stands are used by photographers or hunters and are often referred to as a deer stand or tree stand.
Stands of this type can, of course, also be employed with upright wooden poles or the like, but the most common use is with trees having a diameter on the order of five inches or more. The stand should be of lightweight construction and be capable of being readily assembled and disassembled without the use of any tools. Nature stands are utilized with trees of many different sizes and configurations. Prior art stands have the disadvantage that they often are not suitable for use with trees having unusual shapes and trees that have many low branches or divided trunks. Furthermore, prior art stands make undesired noises or may have components thereof damaged upon movement of the associated tree caused by wind. It is therefore desirable to eliminate any undesired noises and possible damage to the stand irrespective of movement of the tree to which it is attached.


The present invention refers to a floor cleaning machine comprising a brush adapted to scrub the floor with a cleaning, i.e. detergent, liquid in view of removing soil and dirt therefrom, and a wiping device adapted to scrape the floor in order to remove the dirty cleaning liquid therefrom; the wiping device comprises a front flap and a rear flap adapted to elastically and slidably engage the floor so as to define a suction chamber therebetween, wherein the suction chamber is fluidly connected to a suction device, and wherein the front flap is provided with a plurality of indentations of a reduced cross-sectional size to convey the dirty cleaning liquid into the suction chamber; at least a portion of the front flap is provided in the form of a tab that is associated to the same front flap via a rupture edge, wherein such tab is adapted to be removed so as to form a breach or passageway having a broader cross-sectional size in the front flap in order to reduce the speed of the air entering the suction chamber and, as a result, the related suction noise.

I. The Field of Invention
The present invention relates to a floor cleaning machine.
II. Description of Related Art
Floor cleaning devices, i.e. washing-drying machines, usually comprise a brushing device with water and/or a liquid detergent dispensing provision to wash the floor, as well as a wiping device to remove the dirty liquid from the floor and dry up the latter.
Such a wiping device has the purpose of scraping and vacuuming the floor behind the brushing device, in order to remove the dirty liquid therefrom by taking it in through a suction means, with which it is appropriately connected.
The wiping device is usually comprised of a support, to which there are mounted two flaps (or wiping blades, as they are generally referred to in the art) that are made of a rubber-based or rubber-like material to be able to elastically and slidably engage the floor to be cleaned. These flaps, i.e. a front one—facing forwards, i.e. in the forward direction of movement of the machine—and a rear one, are biased, i.e. pressed against the floor so as to substantially act as sealing gaskets and delimitate a suction chamber therebetween, which is connected to the suction or vacuuming means via a conduit. The rear flap has usually a larger thickness and is made of a softer material featuring a greater resistance to water and detergent liquid, since it must perform as to be able to retain the dirty washing liquid inside the chamber for it to be effectively removed by suction.
The front flap has the task of conveying the liquid into the suction chamber and, to this purpose, it is in fact provided with a plurality of indentations or cuts made along the floor scraping border, i.e. the border in contact with the floor, so as to allow the washing liquid to seep into and enter the suction chamber. The provision of such indentations or cuts has the effect of reducing the negative pressure being created by the suction means inside the chamber, but allows for a correct removal of the air-liquid mixture by suction.
While seeping through such indentations or cuts, the air and the liquid generate some noise.
Now, the speed of the air being sucked in through the indentations is higher and, as a result, the negative pressure inside the suction chamber is greater, so the noise generated is higher.
Generally, however, when the negative pressure that is created inside the suction chamber is greater, the ability of the liquid to be effectively removed from the floor by suction is better.
By increasing the overall dimensions of the indentations or cuts in the front flap, i.e. by providing apertures with a broader cross-section, the negative pressure created inside the suction chamber and, as a result, the overall suction capacity are reduced, but the effect of drastically reducing the noise generated by the air being sucked in and passing through the indentations is obtained.
When treating some kinds of floors (typically those paved with tiles and featuring fissures and junctures), the negative pressure shall necessarily be high enough so as to allow the liquid to be correctly and effectively removed by suction, even if this involves—as a consequence—a greater noise emission, which people are willing to accept since the priority—in these cases—lies in ensuring the highest possible suction capacity.
On other kinds of floors (e.g. linoleum-covered floors, marble floors, and the like), the suction capacity may be equally effective even with a lower negative pressure prevailing inside the suction chamber and, therefore, under a reduced emission of noise.
In certain places and environments (e.g. industrial premises, supermarkets, gyms, and the like) the prevailing priority lies in having or obtaining a great suction capacity at the expense of a considerable extent of noise emitted.
In other places (such as hospitals, schools, and the like), people are rather willing to accept a relatively lower suction effectiveness, since the priority lies in this case in ensuring an emission of noise that is as low as possible.
Floor-cleaning equipment manufacturers currently provide front flaps featuring either indentations of a reduced cross-section size, so as to ensure a maximum extent of suction capacity, or larger-sized indentations that favor a low emission of noise, while giving up part of the suction effectiveness.
It has been found, however that, in the case of front flaps provided with indentations with a reduced cross-section size (i.e. aimed at obtaining a maximum extent of negative pressure created inside the suction chamber), the final equipment users themselves tend to manually provide—using scissors or similar tools—larger-sized apertures in view of reducing the noise level of the machines.
It may of course be quite readily appreciated that such tampering is quite difficult job, and further requires a lot of time to be completed, since it involves the front flap to be removed from the wiping device, the additional aperture or apertures to be cut thereinto, and finally the re-processed front flap to be assembled again on to the wiping device.
It can further be readily appreciated that—during the process of making such additional apertures in the front flap, i.e. a process that largely depends on the skills and the experience of the user carrying it out—the front flap may itself be caused—owing to errors in tampering therewith or similar problems—to undergo tears and similar damages that might even impair the good state and operativeness thereof, up to making it necessary for it to be totally replaced.


A moving device includes a moving table for mounting an object thereon and for moving the object, a guiding mechanism for regulating the movement of the moving table, a driving mechanism for generating a force to move the moving table, and a transmission mechanism for transmitting the driving force to the moving table. The transmission mechanism includes at least one set of parallel leaf springs having an oscillation-damping material disposed therebetween.

1. Field of the Invention
This invention relates to a moving device which is used in a measuring apparatus, a semiconductor printing apparatus, a precision machine tool or the like.
2. Description of the Prior Art
In a conventional precision sample moving device, in order to absorb the whirling of a feed screw during revolution, a feed-screw nut has been coupled to a moving platform via parallel leaf springs, as disclosed, for example, in Japanese Patent Application Public Disclosure (Kokai) No. 59-145527 (1984).
The above-described conventional device, however, has the disadvantage that the attenuation of oscillation when the feed-screw nut oscillates is inferior. As a result, the conventional device has, for example, the following disadvantages:
(1) When performing a high-speed positioning operation, the nut oscillates due to the whirling of the feed screw. The oscillation is transmitted to the sample platform to deteriorate positioning time and positioning accuracy.
(2) When an external force is applied to the sample platform, the feed screw and the nut oscillate. The oscillation is transmitted to the sample platform to deteriorate positioning time and positioning accuracy.


A method of obtaining an electrical representation of a radiation image by means of at least one CCD sensor. A stimulable phosphor plate, the area of which is divided into at least two different portions, is exposed to a radiation image. Each of the portions is stimulated by light guided from a light source, the light having a wavelength within the stimulating wavelength range of the phosphor on the plate and causing the phosphor plate to emit stimulated light. The stimulated light from each phosphor plate portion is guided to at least one two-dimensional CCD sensor kept in a static position relative to the phosphor plate portion, such that the CCD detects the stimulated light. The detected stimulated light is converted into an electrical representation of the plate portion, and the electrical representation of each of the different plate portions is combined to form an electrical representation of the radiation image. When using fiber optics a high readout efficiency can be obtained using a broad range of light sources in continuous or pulsed mode.

In the field of digital radiography different methods are already known.
One such method is based upon a conventional phosphor of which the prompt-emitting light is measured directly during the X-ray irradiation using a CCD sensor. The light emitted by the fluorescent phosphor is hereby optically conducted to a CCD. One such system is described in U.S. Pat. No. 5,519,751 where a medical x-ray image processor receives the input data from a two dimensional CCD sensor which is coupled to a phosphor screen by a light conducting member. Due to the fact that a prompt emitting phosphor is used as an x-ray radiation image converting medium, detection can only be performed simultaneous with the exposure. Because the detecting area of the CCD is relatively small (15 by 15 mm), only small X-ray images can be taken at the same time. The application is therefore restricted to e.g. dental exposures. It is only possible to read-out a larger image with a CCD using a lens to image a reduced image of the emitted light onto the CCD. In this case the original image is highly reduced which results in a very low collection efficiency. Then a good signal to noise ratio can only be reached using large X-ray doses. Furthermore, the detection of the radiation image using a prompt emitting phosphor has to be performed in situ. It is not possible to read the image at another location than at the location where it is recorded and at another time than at the time at which the X-ray exposure is performed. Therefore every X-ray apparatus needs to contain a CCD and imaging optics. Due to all these factors the realisation of an x-ray system using CCDs is still very costly and impractical. An other system described in U.S. Pat. No. 4,933,558 uses a stored energy releasing phosphor plate for image detection. After being exposed to an X-ray image the phosphor is stimulated with an appropriate light source and the image recorded in the phosphor plate is readout using a CCD imager. The CCD imager is coupled to the phosphor plate using a lens or Fibre optic bundle. Although this allows the use of a phosphor plate having a size of about 7 times the size of the CCD when using tapered fibre optics, this method is restricted due to the limited size of the phosphor plate which can be used when a certain image pixel resolution is desired. In another embodiment described in U.S. Pat. No. 4,933,558 the phosphor is readout using an array of linear CCDs (each having a certain length but which are only one pixel size wide) continuously scanning the whole phosphor plate with a constant speed. With this arrangement only a small amount of pixels is readout at the same time. It is impossible to obtain a thorough readout of the fluorescent image within a acceptable time period. In U.S. Pat. No. 4,953,038 is described an other system using a stimulable phosphor plate. The sensor used for readout is a CCD sensor operated in time delay integration mode. Although a longer readout time is obtained for each pixel, the method needs a continuous scanning movement of the readout sensor so a great care has to be taken to synchronize sensor movement and readout electronics. The number of readout pixels is relatively small so readout takes a long time.

Method for obtaining an electrical representation of a radiation image using CCD sensors


The invention relates to a blowing lance suspension with integrated medium supply. In accordance with this invention, a U-shaped medium collector box having a horizontal top plate as carrier arm and a first connection surface is provided on the lance carriage. The medium connection pipes lead into this first connection surface. A lance carrier plate is provided, at right angles to the longitudinal axis of the lance, on the top part of the lance. The underside of the lance carrier plate forms a second connection surface into which the medium distributor pipes of the lance lead fittingly. After the lance has been laid down on the carrier arm of the lance carriage, the lance carrier plate is carried by the horizontal top plate, so that between the first and second connection surfaces, the connection of the medium pipes is made through the action of gravity.

This invention relates to a blowing lance suspension with an integrated medium supply for metallurgical blowing lances wherein the blowing lance is mounted on a blowing lance carriage. More particularly, this invention relates to a blowing lance suspension having connection surfaces between the top part of the blowing lance and the lance carriage that lie substantially horizontal.
Blowing lance suspensions having integrated medium supply and horizontal connection surfaces between the lance and the medium supply device are known per se. The primary characteristic of these known arrangements (see for example the patent specifications LU-69-797 corresponding to U.S. Pat. No. 3,972,515 which is assigned to the assignee hereof and incorporated herein by reference and LU-86-985 corresponding to U.S. Pat. No. 4,893,791, which is assigned to the assignee hereof and incorporated herein by reference) is that the primary connection surface points downwards. In contrast, the secondary connection surface, that is, the connection surface belonging to the lance, points upwards.
In the prior art, in order to obtain secure leaktight coupling of the lance to the medium supply device, the lance must be raised by a hoisting device upwardly to the primary connection surface. The lance is rigidly coupled to the medium supply device by means of a coupling device. It will be appreciated that the two operations of raising and coupling are disadvantageously carried out against the pull of gravity.
In addition, the coupling device with its associated drive mechanism, even in an improved version (see patent specification LU-88-017, corresponding to U.S. application Ser.No. 921,327 filed Oct. 13, 1992, which is assigned to the assignee hereof and incorporated herein by reference) is still quite expensive.
Another disadvantage of the device proposed in Ser. No. 921,327 is that a transport clevis must be provided between the crane hook and the top part of the lance in order to transport the lance. This is required in order to bring the top part of the lance to a position under the medium supply device. The removal of this transport clevis after positioning the lance under the medium supply device as well as the initial attachment of the clevis entail complicated manipulations. Moreover, the minimum width of this clevis is determined by the width of the medium supply device, and therefore the lance approach corridor must have a greater than normal width.

Blowing lance suspension with integrated medium supply


Liquid crystal polymer materials used in liquid crystal devices, piezoelectric devices, pyroelectric devices and recording media are described.

Liquid crystals can exist in various phases. In essence there are three different classes of liquid crystalline material, each possessing a characteristic molecular arrangement. These classes are nematic, chiral nematic (cholesteric) and smectic. A wide range of smectic phases exists, for example smectic A and smectic C. Some liquid crystal materials possess a number of liquid crystal phases on varying the temperature, others have just one phase. For example. a liquid crystal material may show the following phases on being cooled from the isotropic phase:--isotropic--nematic--smectic A--smectic C--solid. If a material is described as being smectic A then it means that the material possesses a smectic A phase over a useful working temperature range.
Materials possessing a smectic A (S.sub.A) phase may exhibit an electroclinic effect. The electroclinic effect was first described by S Garoff and R Meyer, Phys. Rev. Lett., 38, 848 (1977). An electroclinic device has also been described in UK patent application GB-2 244 566 A. This particular device helps to overcome the poor alignment problems of electroclinic (EC) devices using a surface alignment that gives a surface tilt within a small range of angles.
When a smectic A phase is composed of chiral molecules, it may exhibit an electroclinic effect, i.e. a direct coupling of molecular tilt to applied field. The origin of the electroclinic effect in a smectic A phase composed of chiral polar molecules has been described by Garoff and Meyer as follows. The application of an electric field parallel to the smectic layers of such a smectic A phase biases the free rotation of the transverse molecular dipoles and therefore produces a non-zero average of the transverse component of the molecular polarisation. When such a dipole moment is present and coupled to the molecular chirality, a tilt of the long molecular axis (the director) is induced in a plane perpendicular to the dipole moment.
In thin samples, for example 1-3 mm, and with the smectic layers tilted or perpendicular with respect to the glass plates the electroclinic effect is detectable at low applied fields.
In an aligned smectic A sample a tilt of the director is directly related to a tilt of the optic axis. The electroclinic effect results in a linear electro-optic response. The electro-optic effect can manifest itself as a modulation of the effective birefringence of the device.
Electroclinic (EC) devices are useful, for example, in spatial light modulators having an output that varies linearly with applied voltage. A further advantage of EC devices is that they have high speed response times, much faster than twisted nematic type devices. One known type of ferroelectric device is bistable, in contrast the EC device is not bistable and has an output that varies linearly with applied voltage.
The electroclinic effect is sometimes referred to as the soft-mode effect see G Andersson et al in Appl. Phys. Lett., 51, 9, (1987).
In general terms, regarding the electroclinic effect, it is advantageous if on applying a small voltage there results a large induced tilt. An increase in induced tilt may result in an increase in contrast ratio. It is also advantageous if a large induced tilt can be obtained at as low a voltage as possible.
It is also advantageous if the relationship between molecular induced tilt and applied voltage is temperature independent. When an increase in applied voltage results in little or no change in induced tilt then the material being tested is generally referred to as exhibiting a saturation voltage effect.
By S.sub.A * is meant a S.sub.A phase which contains some proportion of chiral molecules.
Cholesteric or chiral nematic liquid crystals possess a twisted helical structure which is capable of responding to a temperature change through a change in the helical pitch length. Therefore as the temperature is changed, then the wavelength of the light reflected from the planar cholesteric structure will change and if the reflected light covers the visible range then distinct changes in colour occur as the temperature varies. This means that there are many possible applications including the areas of thermography and thermooptics.
The cholesteric mesophase differs from the nematic phase in that in the cholesteric phase the director is not constant in space but undergoes a helical distortion. The pitch length for the helix is a measure of the distance for the director to turn through 360.degree..
By definition, a cholesteric material is chiral material. Cholesteric materials may also be used in electro-optical displays as dopants, for example in twisted nematic displays where they may be used to remove reverse twist defects. They may also be used in cholesteric to nematic dyed phase change displays where they may be used to enhance contrast by preventing wave-guiding.
Thermochromic applications of cholesteric liquid crystal materials usually use thin film preparations of the materials which are then viewed against a black background. These temperature sensing devices may be placed into a number of applications involving thermometry, medical thermography, non-destructive testing, radiation sensing and for decorative purposes. Examples of these may be found in D G McDonnell in Thermotropic Liquid Crystals, Critical Reports on Applied Chemistry, Vol. 22, edited by G W Gray, 1987 pp 120-44; this reference also contains a general description of thermochromic cholesteric liquid crystals.
Generally, commercial thermochromic applications require the formulation of mixtures which possess low melting points, short pitch lengths and smectic transitions just below the required temperature-sensing region. Preferably the mixture or material should retain a low melting point and high smectic--cholesteric transition temperatures.
In general. thermochromic liquid crystal devices have a thin film of cholesterogen sandwiched between a transparent supporting substrate and a black absorbing layer. One of the fabrication methods involves producing an `ink` with the liquid crystal by encapsulating it in a polymer and using printing technologies to apply it to the supporting substrate. Methods of manufacturing the inks include gelatin microencapsulation, U.S. Pat. No. 3,585,318 and polymer dispersion, U.S. Pat. Nos. 1,161,039 and 3,872,050. One of the ways for preparing well-aligned thin-film structures of cholesteric liquid crystals involves laminating the liquid crystal between two embossed plastic sheets. This technique is described in UK patent 2,143,323.
Ferroelectric smectic liquid crystal materials, which can be produced by mixing an achiral host and a chiral dopant, use the ferroelectric properties of the tilted chiral smectic C, F, G, H, I, J and K phases. The chiral smectic C phase is denoted S.sub.C * with the asterisk denoting chirality. The S.sub.C phase is generally considered to be the most useful as it is the least viscous. Ferroelectric smectic liquid crystal materials should ideally possess the following characteristics: low viscosity, controllable spontaneous polarisation (Ps) and an S.sub.C phase that persists over a broad temperature range which should include ambient temperature and exhibits chemical and photochemical stability. Materials which possess these characteristics offer the prospect of very fast switching liquid crystal containing devices. Some applications of ferroelectric liquid crystals are described by J S Patel and J W Goodby in Opt. Eng., 1987, 26,273.
In ferroelectric liquid crystal devices the molecules switch between different alignment directions depending on the polarity of an applied electric field. These devices can be arranged to exhibit bistability where the molecules tend to remain in one of two states until switched to the other switched state. Such devices are termed surface stabilised ferroelectric devices, e.g. as described in U.S. Pat. No. 5,061,047 and U.S. Pat. No. 4,367,924 and U.S. Pat. No. 4,563,059. This bistability allows the multiplex addressing of quite large and complex devices.
One common multiplex display has display elements, i.e. pixels, arranged in an X, Y matrix format for the display of for example alpha numeric characters. The matrix format is provided by forming the electrodes on one slide as a series of column electrodes, and the electrodes on the other slide as a series of row electrodes. The intersections between each column and row form addressable elements or pixels. Other matrix layouts are known, e.g. seven bar numeric displays.
There are many different multiplex addressing schemes. A common feature involves the application of a voltage, called a strobe voltage to each row or line in sequence. Coincidentally with the strobe applied at each row, appropriate voltages, called data voltages, are applied to all column electrodes. The differences between the different schemes lies in the shape of the strobe and data voltage waveforms.
Other addressing schemes are described in GB-2,146,473-A; GB-2,173,336-A; GB-2,173,337-A; GB-2, 173629-A; WO 89/05025; Harada et al 1985 S.I.D. Paper 8.4 pp 131-134; Lagerwall et al 1985 I.D.R.C. pp 213-221 and P Maltese et al in Proc 1988 I.D.R.C. pp 90-101 Fast Addressing for Ferroelectric LC Display Panels.
The material may be switched between its two states by two strobe pulses of opposite sign, in conjunction with a data waveform. Alternatively, a blanking pulse may be used to switch the material into one of its states. Periodically the sign of the blanking and the strobe pulses may be alternated to maintain a net d.c. value.
These blanking pulses are normally greater in amplitude and length of application than the strobe pulses so that the material switches irrespective of which of the two data waveforms is applied to any one intersection. Blanking pulses may be applied on a line by line basis ahead of the strobe, or the whole display may be blanked at one time, or a group of lines may be simultaneously blanked.
It is well known in the field of ferroelectric liquid crystal device technology that in order to achieve the highest performance from devices, it is important to use mixtures of compounds which give materials possessing the most suitable ferroelectric smectic characteristics for particular types of devices.
Devices can be assessed for speed by consideration of the response time vs pulse voltage curve. This relationship may show a minimum in the switching time (t.sub.min) at a particular applied voltage (V.sub.min). At voltages higher or lower than V.sub.min the switching time is longer than t.sub.min. It is well understood that devices having such a minimum in their response time vs voltage curve can be multiplex driven at high duty ratio with higher contrast than other ferroelectric liquid crystal devices. It is preferred that the said minimum in the response time vs voltage curve should occur at low applied voltage and at short pulse length respectively to allow the device to be driven using a low voltage source and fast frame address refresh rate.
Typical known materials (where materials are a mixture of compounds having suitable liquid crystal characteristics) which do not allow such a minimum when included in a ferroelectric device include the commercially available materials known as SCE13 and ZLI-3654 (both supplied by Merck UK Ltd, Poole. Dorset). A device which does show such a minimum may be constructed according to PCT GB 88/01004 and utilising materials such as e.g. commercially available SCE8 (Merck UK Ltd). Other examples of prior art materials are exemplified by PCT/GB 86/00040, PCT GB 87/00441 and UK 2232416B.
The unit that is the basic building block of a polymer is called a monomer.
The polymerisation process i.e. the formation of a polymer from its constituent monomers does not usually create polymers of uniform molecular weight, rather what is created is a distribution of molecular weights. In order to describe a sample of polymer it is necessary to state the average number of monomers in a polymer this is called the degree of polymerisation (D.P). By how much the majority of polymer molecules differ from this average value (or to describe the spread of molecular weight) is called the polydispersity.
A number of different average molecular weights can be drawn from gel permeation chromatography (GPC) for a given sample including: M.sub.n --number average molecular weight and M.sub.w --weight average molecular weight. The value used to calculate D.P. is usually M.sub.n and polydispersity is usually defmed as M.sub.w /M.sub.n.
Polymers can be made from different types of monomers, in which case the polymer is called a co-polymer. If two types of monomerjoin in a random fashion then the polymer is called a random co-polymer. If the two monomers form short sequences of one type first which then combine to form the final polymer then a block copolymer results. If short sequences of one of the monomers attach themselves as side chains to long sequences consisting of the other type of monomer then the polymer is referred to as a graft copolymer.
In liquid crystal (LC) polymers the monomers can be attached together in essentially two ways. The liquid crystal part or mesogenic unit of the polymer may be part of the polymer backbone resulting in a main chain LC polymer. Alternatively, the mesogenic unit may be attached to the polymer backbone as a pendant group i.e. extending away from the polymer backbone; this results in a side-chain LC polymer. These different types of polymer liquid crystal are represented schematically below. The mesogenic units are depicted by the rectangles. ##STR1##
The side chain liquid crystal polymer can generally be thought of as containing a flexible polymer with rigid segments (the mesogenic unit) attached along its length by short flexible (or rigid) units as depicted in the schematic representation below. It is the anisotropic, rigid section of the mesogenic units that display orientational order in the liquid crystal phases. In order to affect the phases exhibited by the liquid crystal and the subsequent optical properties there are many features which can be altered, some of these features are particularly pertinent to side-chain liquid crystal polymers. One of these features is the flexible part that joins the mesogenic unit to the polymer backbone which is generally referred to as the spacer group. The length and flexibility of this spacer group can be altered. ##STR2##
A number of side-chain liquid crystal polymers are known, for example see GB 2146787 A.
Liquid crystal polyacrylates are a known class of liquid crystal polymer (LCP). LCPs are known and used in electro-optic applications, for example in pyroelectric devices, non-linear optical devices and optical storage devices. For example see GB 2146787 and Makromol. Chem. (1985) 186 2639-47.
Side-chain liquid crystal polyacrylates are described in Polymer Communications (1988), 24, 364-365 e.g. of formula: ##STR3## where (CH.sub.2).sub.m is the flexible spacer group and X is the side-chain mesogenic unit and R is hydrogen or alkyl.
Side-chain liquid crystal polychloroacrylates are described in Makromol. Chem. Rapid Commun. (1984), 5,393-398 e.g. of formula: ##STR4## where R is chlorine.
Patent Application PCT GB 94/00662 describes amongst other things the use of the Baylis-Hillman Reaction to make a range of novel liquid crystal polymers.
A method for the preparation of polyacrylate homo- or co-polymers having the following repeat unit is described in UK patent application GB 9203730.8 ##STR5##
R.sub.1 and R.sub.2 are independently alkyl or hydrogen, R.sub.3 is alkyl, hydrogen or chlorine. m is O or an integer 1-20, W is a linkage group COO or OOC or O and X is a mesogenic group.
One of the main problems with liquid crystal polymers is that they are extremely difficult to align in devices. Essentially there are two techniques which have been used for aligning liquid crystal polymers. It is possible to try to align the liquid crystal polymer in a similar manner as a low molar mass liquid crystal, which is described in more detail below. Alternatively, mechanical techniques can be used such as shearing. Typically mechanical shearing is performed over hot rollers, this technique is generally only suitable for flexible substrates. It is possible to shear a sample between glass slides however the glass slides cannot be sealed in the conventional manner.
Materials and Assembling Process of LCDs by Morozumi in Liquid Crystals Applications and uses, vol. 1 Ed. Bahadur, World Scientific Publishing Co, Pte. Ltd, 1990 pp 171-194 and references therein as the title suggests discusses methods for assembling liquid crystal devices.
The technique for aligning low molar mass liquid crystals is typically as follows. Transparent electrodes are fabricated on the surfaces of the substrates, the substrates typically being made of glass e.g. glass slides. In twisted nematic or super twisted nematic devices, for example, an alignment process is necessary for both substrates. A thin alignment layer is deposited to align the liquid crystal molecules, typically either organic or inorganic aligning layers are used, for example SiO deposited by evaporation is a typical inorganic alignment layer. One method to form the alignment layer involves rubbing the surface by textures or cloths. Polyimides have also been employed for the surface alignment of layers. Polyimide is coated onto the substrates bearing electrodes by a spinner and then cured to form a layer of approximately 50 nm thickness. Then each layer surface is repeatedly rubbed in substantially one direction with an appropriate material. If the liquid crystal molecules are deposited on this layer they are automatically aligned in the direction made by the rubbing. It is often preferable if the molecules possess a small angle pre-tilt typically 2-3.degree.. Higher pre-tilts are sometimes required.
The two substrates are then fixed together for example by adhesive and are kept separate by spacing materials. This results in uniform and accurate cell spacing. A typical adhesive is an epoxy resin. This sealing material is usually then precured. The electrodes may then be precisely aligned for example to form display pixels. The cell is then cured at, for example 100-150.degree. C. At this point the empty liquid crystal cell is complete.
It is at this point that the cell is filled with the liquid crystal material. The opening size in the sealing area of the liquid crystal cell is rather small therefore the cell can be evacuated, for example in a vacuum chamber, and the liquid crystal material forced into the cell via gas pressure. More than one hole in the sealing area may be used. The empty cell is put into a vacuum chamber and then the vacuum chamber is pumped down. After the cell has been evacuated the open region of the sealant is dipped into the liquid crystal material and the vacuum chamber is brought back to normal pressure. Liquid crystal material is drawn into the cell as a result of capillary action, external gases can be applied to increase the pressure. When the filling process is complete the hole or holes in the sealant is/are capped and the cell is cured at a temperature above the liquid crystal material clearing point to make the liquid crystal molecular alignment stable and harden the capping material.
Polymer liquid crystal molecules tend to be more viscous than low molecular weight liquid crystal materials and are therefore more difficult to align and more difficult to fill into devices. Only liquid crystal polymers with low molecular weights can be flow filled into a cell, and once a degree of polymerisation greater than around 30 or 40 repeat units is reached, most liquid crystal polymers become so viscous that flow filling cells is extremely difficult. Much slower cooling is needed in order to try and align liquid crystal polymers and this usually results in poor uniformity of alignment.
Poorly aligned liquid crystal molecules do not result in the fast switching high contrast materials and devices that are generally required.
The above techniques are suitable for many liquid crystal materials including those devices which use liquid crystal materials which exhibit and utilise the smectic mesophase e.g. ferroelectrics. Suitable alignment techniques may also be found in GB 2210469 B.
Devices containing ferroelectric liquid crystal mixtures can exhibit fast switching times (faster than 100 .mu.s), Clark and Lagerwall, Appl. Phys. Lett., 36, 89, 1980. They can be bistable which means that they can be multiplexed at high levels using a line-at-a-time scan technique. Ferroelectric materials continue to receive a large amount of investigative attention due to their application in high resolution flat panel displays. An important feature of devices containing liquid crystalline materials is that they should exhibit a fast response time. The response time is dependent on a number of factors, one of these being the spontaneous polarisation, denoted Ps (measured in nC cm.sup.-2). By adding a chiral dopant to the liquid crystalline mixture the value of Ps can be increased, thus decreasing the response time of the device. Ferroelectric smectic liquid crystal materials, which can be produced by mixing an achiral host and a chiral dopant, use the ferroelectric properties of the tilted chiral smectic C, F, G, H, I, J, and K phases. The chiral smectic C phase is denoted S.sub.C * with the asterisk denoting chirality. The S.sub.C * phase is generally considered to be the most useful as it is the fastest switching. It is desirable that the material should exhibit a long pitch chiral nematic (denoted N*) and S.sub.A phase at temperatures above the chiral smectic phase in order to assist surface alignment in a device containing liquid crystalline material. Ferroelectric smectic liquid materials should ideally possess the following characteristics: low viscosity controllable Ps and an S.sub.C * phase that persists over a broad temperature range, which should include ambient temperature, and exhibits chemical and photochemical stability. Materials which possess these characteristics offer the prospect of very fast switching liquid crystal containing devices.
Ferroelectric LCDs by Dijon in Liquid Crystals Applications and Uses, vol. 1 Ed. Bahadur, World Scientific Publishing Co. Pte. Ltd, 1990 pp 350-360 and references therein discusses alignment processes for smectic phases for low molar mass materials. The filling of cells is believed to be possible only in the isotropic or nematic phase due to the viscosity of smectic phases. Generally materials with the following phase sequence give good alignment:
I-N*-S.sub.A -S.sub.C * or I-S.sub.A -S.sub.C * PA1 I-N*-S.sub.C *
whereas materials with the following phase sequences are more difficult to align:
Typically, therefore, in order to use a liquid crystal material in the smectic phase it will involve heating the material to the nematic or isotropic phase and allowing it to cool slowly into an aligned smectic state. Should this technique be applied to a polymer liquid crystal material then the cooling time is usually very much longer in order to assist the alignment, though very often the alignment is poor.
There is a continued need for new liquid crystal polymers which possess the properties that allow them to be used in devices including one or more of the known electro-optic devices.

The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland


A tracker controller system in which a pair of photo-resistive cadmium sulfide sensors mounted in the shadow of a shade pole generate a voltage signal proportional to their resistive values which signal is delivered to a comparator circuit that causes a tracker driver to operate when the voltage signal falls outside of a voltage window established by the comparator circuit.

The present invention relates to methods and apparatus for tracking the sun and more particularly, to methods and apparatus by which a photovoltaic panel or any other sun energy conversion device can be positioned to capture the maximum useful radiation available from the sun as it makes its diurnal trek across the skies.
While the present invention will be presented in the context of tracking the radiation from the sun, the invention is applicable to tracking of radiation of other sources as well, as will be apparent to those versed in the art, and as will be obvious from the description which follows.
It has long been recognized that for the most efficient generation of electrical energy from solar radiation it is necessary for the converting apparatus to track the path of the sun. Numerous schemes have been devised for achieving this goal, but prior to the present invention, none has provided a truly practical solution.
Tracker controls using freon as the active medium are known in the art, but are characterized by unreliability in even ideal atmospheric conditions and outright inoperability when either the temperature or the wind conditions are adverse, and are virtually useless for concentrator collectors where accuracies of less than five degree are demanded.
Highly sophisticated, computer-driven trackers which employ a database to calculate the position of the sun at any given instant of time for a particular location on the planet have also been devised, but are only experimental and have not found any commercial success whatsoever due to their extremely high cost and periodic need for calibration.
The present invention, for the very first time, provides methods and apparatus for tracking the sun which are simple in design and inexpensive to produce, while at the same time precise to within a fraction of a degree under any temperature conditions or windy weather, as well as more ideal conditions. In addition, the present invention provides a tracking device which is self-powered, instantly recognizes atmospheric conditions which affect the collection of solar radiation and modifies its operation to best suit those conditions, prevents elevation "skying" in diffuse radiation conditions and automatically returns to the east after sunset.
An additional object of the invention is to provide a low cost, high precision tracker control that tolerates imbalances in sensor pairs due to manufacturing tolerances, environmental conditions and aging.
Accordingly, it is an object of the present invention to provide a low-cost, highly accurate control system for a solar tracker which maximizes the gathering of solar energy.
It is a further object of the present invention to provide a method for controlling the position of a solar collector to maximize the amount of solar radiation that it collects.
Yet another object of the present invention is to provide a control system for a solar tracker that automatically recognizes a variety of atmospheric conditions affecting the collection of solar radiation and modifies the tracker's operations to best suit those prevailing conditions.
Another object of the invention is to provide a method and apparatus by which a solar tracker will automatically return to an east position after the sun sets.
Yet a further object of the present invention is to provide methods and apparatus for solar tracking that will prevent the elevation control from "skying" in diffuse light conditions.
Other objects and advantages will appear from the following description of a preferred embodiment of the invention and the novel features will be particularly pointed out in the claims.

Radiation source detector and tracker control having a shade pole and radiation responsive surface in the shape of narrow bands


Provided are an electromagnetic shielding film capable of improving brightness, a plasma display panel (PDP) filter using the electromagnetic shielding film, a PDP device including the electromagnetic shielding film, and a method of manufacturing the electromagnetic shielding film. The electromagnetic shielding film includes a transparent substrate, an electromagnetic shielding film pattern which is formed on the transparent substrate and whose face opposite to the transparent substrate is blackened, and a black conductive layer pattern which is formed on the electromagnetic shielding film pattern. The method includes (a) forming a non-conductive layer on a conductive substrate, (b) forming a non-conductive layer pattern by patterning the non-conductive layer, (c) forming a black conductive layer pattern on the conductive substrate exposed by the non-conductive layer pattern, (d) forming an electromagnetic shielding film pattern on the black conductive layer pattern, (e) oxidizing the electromagnetic shielding film pattern to blacken the same, and (f) separating the black conductive layer pattern and the electromagnetic shielding film pattern from the conductive substrate using a transparent substrate on a face of which an adhesive is formed.

1. Field of the Invention
The present invention relates to an electromagnetic shielding film, a plasma display panel (PDP) filter using the electromagnetic shielding film, a PDP device including the electromagnetic shielding film, and a method of manufacturing the electromagnetic shielding film. More particularly, the present invention relates to an electromagnetic shielding film having a high refractive index in a visible light region, which can improve brightness and image quality by blackening not only a portion of the shielding film facing a user's side but also a portion opposite to the user's side, a method of manufacturing the electromagnetic shielding film, a PDP filter using the electromagnetic shielding film, and a PDP device including the electromagnetic shielding film.
2. Description of the Related Art
As modern society becomes more information-oriented, photoelectronic devices advancing and being more widely used. In particular, image display devices are widely used in a variety of applications, including TV screens, monitors of personal computers, etc. Wide screens and a thin build have become the mainstream technology for high performance image display devices.
Plasma display panels are gaining popularity as a next-generation display device to replace the CRT because of advantages in thinness, and that a big screen can be readily fabricated with a plurality of units. A PDP device includes a plasma display panel on which an image is displayed using a gas discharge phenomenon, and exhibits superior display capabilities, including high display capacity, high brightness, high contrast, clear latent image, and a wide viewing angle.
In a PDP device, when a direct current (DC) or alternating current (AC) voltage is applied to electrodes, a discharge of gas plasma is created, resulting in the emission of ultraviolet (UV) light. The UV emission excites adjacent phosphor materials, resulting in electromagnetic emission of visible light.
Despite the above advantages, PDPs have several problems associated with driving characteristics, including an increase in electromagnetic wave radiation, near-infrared emission, and phosphor surface reflection, and an obscured color purity due to orange light emitted from helium (He) or xenon (Xe) used as a sealing gas.
The electromagnetic wave and near-infrared ray generated in PDPs may adversely affect human bodies and cause malfunction of precision machines such as wireless telephones or remote controllers. Thus, in order to make use of such PDPs, there is a desire to reduce the electromagnetic wave and near-infrared rays emitted from the PDPs. In this respect, various PDP filters have been used for the purposes of, for example, shielding electromagnetic waves or near-infrared rays emitted from the PDPs, reducing reflection of light and/or enhancing color purity. Various PDP filters having an electromagnetic wave shielding function, a near-infrared rays shielding function, an antireflection function, and/or a color purity enhancing function, can be formed together with the PDPs.
A plasma display panel device includes a panel assembly that has a discharge cell in which gas discharge occurs and a PDP filter that shields electromagnetic waves and near-infrared rays.
The PDP filter, which is mounted on the entire surface of the panel assembly, should interfere as little as possible with transparency.
In a PDP device, an electric current flowing between a driving circuit and an alternating current (AC) electrode and a high voltage between electrodes used for plasma discharge are the main causes of electromagnetic waves. The electromagnetic waves generated by such causes are mainly in the frequency band of 30-200 MHz. Generally, a transparent conductive film or a conductive mesh that maintains a high visible light transmittance and a low refractive index in a visible light region is used as an electromagnetic shielding layer for shielding the generated electromagnetic waves.
An electromagnetic shielding layer made of a conductive mesh exhibits a superior electromagnetic shielding capability. An electromagnetic shielding layer made of a transparent conductive film such as an Indium Tin Oxide (ITO) film generally takes the form of a multi-layered thin film in which a metal thin film and a high refractive index transparent thin film are alternately coated. A main element of the metal thin film is silver (Ag) or an alloy of silver (Ag).
Hereinafter, a conventional method of manufacturing an electromagnetic shielding film including a conductive mesh will be described with reference to FIGS. 1A through 1C. FIGS. 1A through 1C are sectional views of sequential processing steps for explaining the conventional method of manufacturing an electromagnetic shielding film.
As shown in FIG. 1A, a metal thin film 30 is attached to a transparent substrate 10 using an adhesive 20 having appropriate adhesion strength through lamination. The transparent substrate 10 is generally a polyethylene terephthalate (PET) film. As shown in FIG. 1B, a photoresist pattern 40 is formed by coating a photoresist on the metal thin film 30 and patterning the photoresist using a photolithographic process (an exposure process and a development process). As shown in FIG. 1C, an electromagnetic shielding film pattern 32 is formed by etching the metal thin film 30 using the photoresist pattern 40 as an etching mask. After the photoresist pattern 40 used as the etching mask is removed, the electromagnetic shielding film pattern 32 on the transparent substrate 10 is blackened. The electromagnetic shielding film pattern 32 is generally made of a metal thin film having high electromagnetic shielding performance. However, when the electromagnetic shielding film pattern 32 is formed of a metal thin film, the inherent high refractive index of the metal thin film in the visible light region poses a problem. In particular, copper, which is widely used as the electromagnetic shielding film pattern 32, has a refractive index of 60% or more in the visible light region. Thus, when a PDP filter including the electromagnetic shielding film pattern 32 formed of copper is used on a PDP device, the brightness of the PDP device drops significantly. To reduce the refractive index of a metal, the electromagnetic shielding film pattern 32 is blackened. Referring to FIG. 1C, three faces of the conventional electromagnetic shielding film pattern 32, except for a face opposite to the transparent substrate 10, are blackened. In general, blackened portions of the electromagnetic shielding film pattern 32 face a user's (or viewer's) side of the PDP device. Thus, the refractive index of the PDP device in the visible light region is reduced from the viewpoint of the viewer.
However, since a portion of the electromagnetic shielding film pattern 32 facing the panel assembly's side is not blackened, the PDP device cannot obtain high brightness. In other words, light generated by the panel assembly of the PDP device is reflected from the electromagnetic shielding film pattern 32 and then enters the panel assembly, resulting in light superposition. As a result, the brightness of the PDP device drops, degrading image display capability.
Another conventional technique regarding a PDP filter having an electromagnetic shielding film pattern is disclosed in Japanese Patent Application No. Hei 11-119675 filed on Oct. 16, 1997, which is directed to a method of manufacturing an electromagnetic shielding plate. In the electromagnetic shielding plate, only a face opposite to the viewer's side is blackened. As a result, like the prior art shown in FIGS. 1A through 1C, light generated by a panel assembly is reflected from the electromagnetic shielding plate and then enters the panel assembly, resulting in degradation of the brightness and performance of a PDP device.

Electromagnetic shielding film, plasma display panel filter using the electromagnetic shielding film, plasma display panel device including the electromagnetic shielding film, and method of manufacturing the electromagnetic shielding film