Optical display systems and methods for providing three-dimensional and two-dimensional convergence corrected images to a user are described. The optical display systems may include at least two image generators producing a plurality of rays forming a plurality of images. A diffraction enhanced imaging system may be configured to collect the rays produced and control convergence angle of each ray at specific wavelengths into an optical waveguide. An in-coupling diffraction system may couple the rays into the optical waveguide. A wavelength compensated beam expander may expand horizontal extension of the images and an output coupling and vertical expansion system may magnify the images in a vertical direction and direct light towards a user at specific angles creating a wide field of view.

Augmented reality (AR) and virtual reality (VR) systems promise to revolutionize the way humans interact with each other and the world around them. These technologies provide human eyes additional information that either augments or supplant visual information received from the outside world to entertain, inform and/or educate a user. Generally, VR systems immerse a user in a virtual world, limiting input from the outside world, and AR systems superimpose information and/or virtual images onto a scene observed by a user. The user may be allowed to engage in interactive games, view information (e.g., instruction manuals, handbooks) while performing a task or exploring, conduct virtual training, and/or visualize digital information. For example, AR systems may use a head's up display (HUD), overlaying the outside world with images and/or data screens containing information adding to a user's experience.
In general, AR displays consist of four common main subsystems, each of which may impact the display performance. First, the optical system generates, manipulates and presents images to the viewer in a manner that causes a user to perceive existence of virtual objects within an outside visual world. Second, environmental mapping may use cameras and sensors to obtain knowledge of the surrounding environment, such as walls, desks and other surfaces that could support images and detect a user's movement within the environment. Third, head and eye tracking systems may provide feedback on where a user wishes to look and the existence of any alignment issues for which the system must accommodate. Finally, extensive software and hardware processing systems may contain the computing power that controls, coordinates, and drives the actions of the other three subsystems.
Design and implementation of the optical system generally use either bulk optics systems or waveguide systems. Bulk optical systems use a combination of lenses and custom designed prisms to magnify and distribute the image to a user's eye. The image generator projects light into a free-form prism—the shape of the prism deviates from regular geometric figures—and total internal reflection (TIR) at the surface combined with the shape provides the means to magnify the image and direct the magnified image toward a user's eye. A second prism placed nearly in contact with the first prism corrects distortions caused by the first prism and may allow light from the external world to pass through to a user's eye. This solution possesses several drawbacks that may limit use for practical applications, including the large size and weight of the prisms, incomplete correction of image distortions, small field of view (FOV), and no practical path to implementing methods to resolve vergence-accommodation conflict. Examples of this type of system include multi-focal plane displays and Google Glass, manufactured by Google having a principle place of business in Mountain View, Calif.
The more current offering of AR head-mounted displays use an optical waveguide system to connect the output of the image generator to a user's eye. The waveguide generally may consist of a piece of glass cut thin in one dimension, typically in width. Light rays propagate through the waveguide by TIR, and optical elements placed within the waveguide or along the walls of the waveguide provide means to couple light into the waveguide from the image generator, modify the magnification and divergence of the image, and couple the light out of the waveguide towards the user's eye.
Present waveguide systems use either diffractive or reflective optical elements in conjunction with the waveguides. Reflective elements possess an advantage of operating at all RGB wavelengths, greatly reducing the number of waveguides needed. Current implementations of such systems, however, suffer from bulkiness and scattering that may deteriorate image quality. Most systems may utilize diffractive optical elements to overcome the size and scattering constraints of the reflective elements. Diffractive elements consist of periodic variations in the waveguide's refractive index (holographic optical elements or HOEs), periodic variations in the surface structure, created by patterning or cutting of material on the waveguide surface, computer-generated holograms (CCH), sub-wavelength digital elements (SWE) or dynamic diffractive optics.
Diffractive elements may present many advantages, including small size and weight, the ability to create them directly on or within the waveguide, the ability to tune the element to pass light from the external scene with minimal distortion or dimming, and ease of design. Diffractive elements also may present three key disadvantages. First, the elements may operate in a very narrow band of wavelengths, and thus systems based on diffractive elements may require three waveguides, with each waveguide individually processing one of the RGB wavelengths thus adding to the size and cost of the display system. Second, diffractive elements display high angular selectivity, which may limit the range of ray angles directed by the grating towards the user, thus significantly limiting the FOV achieved by the display. Third, many of the diffractive elements currently in use have complex shapes that may require lengthy and/or costly manufacturing processes. Differences in the use and implementation of the optical elements drive the differences in performance achieved by existing display offerings.
Many development-level systems currently exist in the market that attempt to harness and deliver the potential of AR, however such systems suffer from a number of issues that limit their potential and/or effectiveness for long term wearing and broad spectrum adoption. For example, existing systems may limit the field of view (FOV) presented to a user. The human eyes capture images from angles over 180 degrees horizontally and 60 degrees vertically. Current optical systems used to present three-dimensional (3D) images to a user's eyes may restrict the field of view (FOV) to 30 degrees by 17 degrees. This limitation may decrease the amount of information the system is able to present to the user in a single frame. The following prior art system provide an overview of those seen typically within the industry.
The BAE System having a principle place of business in Farnborough, United Kingdom, manufacturers the Quantum Display. The Quantum Display generally utilizes a set of diffraction gratings expanding the exit pupil and generating a range of output ray angles. The display positions the image projector at a specific angle with respect to a horizontal waveguide in order to accommodate for the angular selectivity of the diffraction gratings. The optics and mechanics required to achieve the optimal launch conditions add significantly to the size and weight of the display, Light propagating through the first waveguide interacts with a diffraction grating placed or etched on the top surface, and the grating diffracts a portion of the light into a vertical waveguide at each point along horizontal waveguide. A second grating on the surface of the vertical waveguide performs a similar function, coupling light out at each point of the waveguide surface at a range of angles determined by the design of the diffraction grating. The current design projects a collimated output beam and thus produces an output at infinity, and does not provide for any accommodation allowance. The display produces a 30° FOV for one eye (monocular) and uses only one set of waveguides and gratings, limiting current versions to monochrome image generation. The angular positioning of the source and the relatively large thickness of the waveguide make expanding the system to binocular, RGB image generation impractical.
The Lumus display, as described in patent applications filed by Lumus (U.S. Pat. No., 7,391,573, U.S. Ser. No. 12/596,823 and U.S. Ser. No. 12/092,818, for example), generally utilizes a set of reflective surfaces to perform in-coupling, expand the exit pupil and generate a range of output angles. The reflective surfaces rely on the reflection and transmission of light at the boundary between two materials of different refractive index. Each reflector in the waveguide uses a multi-layer coating to produce a partially reflecting mirror. Light rays striking the mirror at certain angles are partially reflected, sending light toward the user's eyes. An element design may prevent reflection from the back of the element, which would send light out the side or rear of the waveguide, away from the user's eye. Several elements distributed along the length of the waveguide couple light out from an extended length along the horizontal direction, effectively expanding the exit pupil in this direction. A similar optical element at the waveguide input couples light into the waveguide from an image generator. A series of lenses, mirrors, and prisms conditions and converges the light from the image generator to coupling and create the divergent beam to present a virtual image to the user. An additional optic may distribute light in the vertical direction to increase the exit pupil in the vertical direction as well as the horizontal direction.
The Lumus display exhibits many design challenges that may limit effectiveness. First, the in-coupling system requires custom, heavy, and bulky optics and a 45° angle, adding weight, size and cost to the system. Second, the eye pupil expansion in both the vertical and horizontal direction may occur relatively slowly, requiring the beam to travel a long distance within the waveguide (around half an inch) before reaching the out-coupling reflective elements. As a result, only a small fraction (around ⅓rd) of the glass area in front of the user's eye may contribute to the production of an image, creating significant dead space in the display. Since most of the FOV produced by a display depends on the size of the emitting area, the small image-producing area greatly restricts the FOV to below 30 degrees. Third, the in-coupling optical design may need to compensate for the polarization-dependent nature of the reflective out-coupling elements. To ensure that each polarization state reflects the same amount of power at each mirror, the in-coupling system may need to carefully control the angle at which each state enters the waveguide. The solution used in the Lumus display contributes to the size, weight and cost of the system.
Fourth, the display produces virtual images at a fixed accommodation and provides no method for adjusting the accommodation to address the vergence-accommodation conflict. In natural viewing, a user's eyes adjust to objects at different distance by changing the focus of the lens (accommodation) to produce a clear image on the user's retina, and by rotating the eyes inward or outward such that the line of sight from the two eyes may converge at the same distance as the object (vergence). The Lumus display presents images at a fixed distance from the eyes such that the images create a virtual object at a perceived distance from the viewer. The eyes may rotate to adapt the vergence based on perceived depth, but the eyes remain focused on the screens, causing an unnatural disconnect between the vergence and accommodation activities. This disconnect may cause moderate to severe problems for a user, including eye strain, headaches and discomfort or disorientation. Further, such issues may worsen over extended viewing periods.
Lastly, the current design of the reflective layers of the Lumus display produces scattering, which may reduce image clarity and/or may increase power required to produce an image. Increased power requirements may strain the limited battery capacity, limiting use time.
The Hololens system is manufactured by Microsoft, having a principle place of business in Redmond, Wash., and utilizes a series of specialized diffractive gratings to perform in-coupling, exit pupil expansion, and out-coupling. Generally, light from the image generator may enter perpendicular to the waveguide and couple into the waveguide at specific angles through a specially designed diffraction grating. The Hololens system is further described in the article "Diffractive optics for virtual reality displays," Journal of the Society for Information Display, Vol. 14, No, 5, pp. 467-475, 2006, and is herein incorporated by reference in its entirety. The grating possesses a tilted structure that couples light in the outward direction toward the eye, with little or no power directed away from the eye. An extended, cone-shaped grating panel uses a similar grating structure to expand the exit pupil in the horizontal direction, directing fractions of light to the larger grating, which expands the exit pupil in the vertical direction. The area of the larger grating may effectively define the Hololens' exit pupil. The modulation depth of both gratings increases with distance from the in-coupling point such that the same amount of power reflects from each point of the grating to produce a uniform intensity image. A liquid crystal display contained in a separate layer provides selective occlusion of the external scene to improve image contrast.
The Hololens design presents many design challenges and choices that may limit the system effectiveness and commercial viability. First, the design of the diffraction gratings makes the gratings exceedingly difficult and quite costly to manufacture. Second, the diffraction gratings operate efficiently at only a single wavelength. To project RGB images, the display uses three parallel waveguides, one for each color, with alignment carefully controlled to match pixel positions in each waveguide. Each eye therefore may require nine of the costly and complicated gratings, for a total of 18 gratings, quickly driving the cost of the system out of the range of most potential users. The use of multiple layers also increases the size and weight of the display, particularly at the front. Third, difficulties in producing the gratings may also limit the maximum area of the out-coupling grating and thus may limit the FOV. The Hololens achieves a FOV of 30 degree horizontally and 17 degrees vertically resulting in a restricted virtual world for the user. Such a small FOV restrict the user's ability to work with multiple objects simultaneously and/or view an entirety of a virtual scene (e.g., objects on edge of scene may disappear or cut-off). Because of the limited FOV, the user can typically see only one complete object at a time, with other objects out of view or only party visible, contrary to the wide FOV concept pictures presented on the Hololens web page. In order to view a complete scene, a user may be required to turn their head and center each object within the FOV, causing other objects to disappear and/or placing motion strain on a user's neck. Lastly, the fixed nature and angular selectivity of the gratings precludes adding optical components that would adjust beam divergence to alleviate the vergence-accommodation conflict.
The optical display manufactured by Magic Leap, having a principle place of business in Plantation, Fla., and described in U.S. Pat. No. 8,950,867, "Three Dimensional Virtual Augmented Reality Display System," and U.S. Pat. No. 9,310,559, "Multiple Depth Plane Three-dimensional Display Using a Waveguide Reflector Array Projector," utilizes a combination of beam-splitters and micro-reflectors to produce the only prior art display attempting to address the accommodation-vergence conflict. Generally, light couples from the image generator into a coupling tube, with the coupling process using a fiber or diffractive element, depending on the specific implementation. The coupling tube may contain a series of beam splitters that reflect a portion of the light into an array of waveguide tubes. The coupling tube may expand the exit pupil in the vertical directions. Each waveguide tube contains a series of curved reflective elements that serve to expand the exit pupil in the horizontal direction (similar to the Lumus display described herein) and to produce a specific divergence in the beam that may cause the virtual image to appear at a specific distance from the user. To produce images at varying distances, multiple coupling-waveguide tube combinations may be stacked in parallel with each combination containing reflective elements of different curvature. The total system may produce images at twelve discrete distances, and the system may produce a distance continuum by illuminating adjacent combinations with different optical power ratios. Switches or other elements select the amount of power delivered to each layer in the overall stack.
The Magic Leap design presents a number of challenging design issues that has prevented the completion of a working prototype. First, the stacked layers of coupling-waveguide tube combinations prove challenging and quite difficult and costly to produce. One such stack may require manufacturing of multiple tubes, each with multiple reflective elements, and each layer of tubes requiring a different curvature for the reflective elements. Second, the size of one such stack, coupled with the need to produce a separate stack for each color to produce an RGB image, may cause the size and weight of the display to grow rapidly. The thickness of the display may exceed that of either the Hololens or Lumus displays. Third, little information exists on the method for implementing layer selection and distribution of power amongst the layers, leaving a number of design challenges unsolved based on the present information available. Fourth, light from one layer must pass through one or more other layers as the light travels to the eye, which raises the possibility of cross-talk and scattering issues that may likely degrade image quality.
As such, there exists a need within the art for a low cost, lightweight and broad FOV optical display system to realize the potential of AR and/or VR systems.

Optical display system for augmented reality and virtual reality


A method is provided for driving a half bridge circuit that includes a first transistor and a second transistor that are switched in a complementary manner. The method includes generating an off-current during a plurality of turn-off switching events to control a gate voltage of the second transistor; measuring a transistor parameter of the second transistor during a first turn-off switching event during which the second transistor is transitioned to an off state, wherein the transistor parameter is indicative of an oscillation at the first transistor during a corresponding turn-on switching event during which the first transistor is transitioned to an on state; and activating a portion of the off-current for the second turn-off switching event, including regulating an interval length of the second portion for the second turn-off switching event based on the measured transistor parameter measured during the first turn-off switching event.

Many functions of modern devices in automotive, consumer and industrial applications, such as converting electrical energy and driving an electric motor or an electric machine, rely on power semiconductor devices. For example, Insulated Gate Bipolar Transistors (IGBTs), Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and diodes, to name a few, have been used for various applications including, but not limited to switches in power supplies and power converters.
A power semiconductor device (e.g., a power transistor) usually comprises a semiconductor structure configured to conduct a load current along a load current path between two load terminal structures of the device. Further, the load current path may be controlled by means of a control electrode, sometimes referred to as gate electrode. For example, upon receiving a corresponding control signal from, e.g., a driver unit, the control electrode may set the power semiconductor device in one of a conducting state and a blocking state. Accordingly, the power semiconductor device behaves like a switch with on and off states (i.e., conducting and blocking states, respectively).
A power transistor is a power semiconductor device that may be used to drive a load current. There is a turn-on process and a turn-off process for switching the power transistor on and off. During the turn-on process, a gate driver integrated circuit (IC) is used to provide (source) a gate current to the gate of the power transistor in order to charge the gate. In contrast, during the turn-off process, the gate driver IC is used to draw (sink) a gate current from the gate of the power transistor in order to discharge the gate and thus lower the gate voltage.
A large number of such circuits work with so-called hard switching. During the transition from blocking to conducting operation of the power transistor, i.e., the so-called switch-on process, both blocking voltage and current flow through the power transistor exist simultaneously for a short time. This inevitably leads to switching losses. With the goal of highly efficient circuits and ever higher switching frequencies, it is necessary to reduce the switching losses of the component.
For driving a load in this manner, two power transistors are typically arranged in a half-bridge configuration. A first power transistor, when on, is responsible for conducing load current in order to source the load current to the load while its complementary power transistor is turned off (i.e., the second power transistor is in blocking mode). In order to sink load current from the load, the roles of the two transistors are reversed. Here, the second power transistor, when on, is responsible for conducing load current in order to sink the load current from the load while its complementary power transistor is turned off (i.e., the first power transistor is in blocking mode). The power transistor that is switched on for either sourcing or sinking load current is referred to as the active power transistor, whereas the power transistor that is switched off while the other is switched on is referred to as the complementary power transistor or passive power transistor. The roles between the two half-bridge power transistors change in a complementary manner, where one power transistor is the active power transistor and the other power transistor is the passive power transistor depending on whether load current is being sourced to or sinked from the load. Thus, both power transistors operate as the active power transistor and as the passive power transistor, with the first power transistor being the active power transistor and the second power transistor being the passive power transistor while load current is provided to the load and with the first power transistor being the passive power transistor and the second power transistor being the active power transistor while load current is drawn from the load.
The switching behavior of the power switch is set by the control at the control terminal of the power transistor. Simple control systems work with two voltage levels and a series resistor for voltage-controlled components. The smaller the series resistor, the faster the switching speed and the lower the switching loss. However, the switching performance of the simple control system is mostly insufficient. On the one hand, the series resistor cannot be selected arbitrarily small, since a voltage oscillation tendency exists at the passive power transistor when the active switch is switched on quickly. In addition to the voltage oscillation tendency, there is also the risk of an electrical overload of the passive power transistor due to switching too fast.
On the other hand, the simple control results in a uniform control behavior, which is constant across all operating points of the active power transistor. These operating points depend on the following parameters: VDC, drain current ID, the junction temperature of the power transistor, and the gate driver voltage applied to the gate. However, due to the large operating range in which the power transistor is operated, especially for silicon carbide (SiC) transistors, this results in a control which does not behave optimally for a wide operating range (i.e., for a wide range of operating points).
Oscillation is considered undesirable in terms of electromagnetic compatibility or electromagnetic interference emission. However, it is not easy to set a clear switching speed limit because the behavior of the overall system, including the switching speed limit itself, always depends on the circuit environment. Also, with regard to the voltage oscillation tendency of the passive power transistor, the "simple control" cannot be used to set the switch-on process of the active power transistor optimally for each operating point.
The oscillation is considered undesirable in terms of electromagnetic compatibility or electromagnetic interference. However, it is not easy to set a clear switching speed limit. This switching speed limit value always depends on the soldering environment. Also, with regard to the tendency to oscillate, "simple control" means that the switching process cannot be optimally set for each operation point vector.
To achieve fast turn-on of the active power transistor and small voltage oscillations of the passive switch for the whole operating range, an improved control is necessary.
In order to optimize the switching process of modern power electronic switches, including SiC transistors, control devices with two-stage or multi-stage switching speeds are often used. This more complex control can improve the conflict of objectives mentioned above.
The necessary setting of a time duration or a temporal portion of the respective switching speed is strongly dependent on the operation point vector. As a result of this dependency, a control or regulation should be used that sets the corresponding time duration or temporal portion of a switching stage implemented by the control device for a respective operation point vector of the power transistor. Therefore, an improved device that enables regulation of a time duration or a temporal portion of a switching stage for each operation point of the power transistor may be desirable. Namely, to achieve fast turn-on of the active power transistor and small voltage oscillations of the passive switch for the whole operating range, an improved control is desired.

Method for reducing oscillation during turn on of a power transistor by regulating the gate switching speed control of its complementary power transistor


An apparatus, method and computer program product are provided for predicting wrong-way-driving events. A WWD event defines an event in which a vehicle travels in a direction opposing a traffic direction designated for a portion of a road. In one example, the apparatus estimates a likelihood of portion of the road inducing a wrong-way-driving (WWD) event by using a machine learning model as a function of map data, sensor data, or a combination thereof. If the likelihood satisfies a threshold, the apparatus updates a map layer to indicate the WWD event at the portion of the road.

Autonomous vehicles rely on map data to traverse a road network; however, since attributes of the road network dynamically change over time, map data indicating such attributes may be outdated. Autonomous vehicles that rely on such map data may deviate from their designated paths of travel. For example, one of such vehicles may determine that the vehicle is driving in a lane at a direction that opposes a traffic direction designated for the lane (as indicated in the map data). Such scenario may increase a likelihood of rendering adverse road conditions, such as accidents.
The listing or discussion of a prior-published document or any background in this specification should not necessarily be taken as an acknowledgement that the document or background is part of the state of the art or is common general knowledge.

Apparatus and methods for predicting wrong-way-driving events


A heater for heating the interior of a utility vehicle, such as a golf cart or the like, the utility vehicle having a dashboard, the heater including a portable heating source, the portable heating source including a pressurized tank of a flammable gas, at least a portion of an exterior surface of the pressurized tank being substantially cylindrical, a burner mechanism for receiving the flammable gas from the pressurized tank and for combusting the flammable gas, a heat deflector for directing heat released by the combusted gas, and a pressure regulating mechanism for supplying a regulated flow of the pressurized gas to the burner mechanism, and a heater bracket for securing the portable heating source to the dashboard of the utility vehicle, the heater bracket including a back plate, a pair of lateral side plates, one each of the lateral side plates extending outward from a lateral side of the back plate, a bottom plate, the bottom plate extending outward from a bottom side of the back plate, a mounting flange, the mounting flange extending outward from a top side of the bottom plate, a retaining strap mechanism for retaining the portable heating source against the back plate, between the pair of lateral side plates, and on top of the bottom plate, and a releasable latch mechanism for releasably latching the retaining strap mechanism.

1. Field of the Invention
The present invention relates to a heater for heating the interior of a small utility vehicle, for example, a golf cart. Even more particularly, the invention relates to a bracket that can accommodate commercially available portable gas fired heaters.
There are many avid golfers throughout the world that play every day and in all types of weather, and many of these players own their own golf carts. There are also those, such a maintenance personnel, who are obligated to be on the course in extreme weather conditions. The invention described and claimed herein would be a welcome addition to the golf carts (or utility vehicles) used for either of these activities.
2. Description of the Related Art
U.S. Pat. No. 4,899,931 relates to a golf cart heater having an adapter bracket that is provided with a rectangular cutout for receiving a similarly shaped gas fuel burning element and an arcuate cutout for supporting a gas fuel bottle oriented substantially on its side, the burning element and the bottle being connected to one another by a supply hose.
U.S. Pat. No. 4,213,592 discloses a bracket assembly for mounting a fire extinguisher thereon that includes a back plate having a lever equipped latch for retaining the fire extinguisher against the back plate, a lug for engaging the bottom of the extinguisher, and an elastomeric pad for ejecting the extinguisher away from the back plate upon tripping of the lever equipped latch.
U.S. Pat. No. 4,997,157 relates to a bracket assembly for mounting a fire extinguisher that includes a base unit, and a strap that passes through cutouts provided in the base unit, so that the strap is interlocked with the base unit when the base unit is secured to a wall.
Finally, U.S. Pat. No. De. 245,929 discloses a design for a fire extinguisher bracket, and U.S. Pat. No. De. 319,539 discloses a design for a holder for a vehicle fire extinguisher, flare, and maps.


A wall strap tensioner for tensioning a wall strap of a metal wall. The wall strap tensioner includes first and second links pivotally connected together. A fastener is secured to each of the first and second links for engaging and fastening to the wall strap. Disposed about the opposite end of the tensioner is a flexible cable adapted to be secured to a portion of the metal wall. A connector connects to the flexible cable and a handle is pivotally connected to the connector and movable between first and second positions. Once the handle assumes the second position, the metal strap is tensioned and can be fastened to an appropriate area of the metal wall.

Metal wall sections are commercially fabricated and delivered to construction sites for erection. Typically metal wall sections include upper and lower channel sections and a series of spaced apart metal studs extending between the upper and lower channel sections. In some cases, columns are provided about opposite end sections of the wall. Further, in some cases, the corner areas of the metal wall section are reinforced.
In many cases, it is advantageous to provide additional structure rigidity by incorporating one or more bridging members or by utilizing diagonal strapping. Diagonal straps provide rigidity to the wall section as a whole. When used in prefabricated modular wall sections these diagonal straps extend from opposed corners and cross about a center area of the wall section. Diagonal straps have applications in places other than in prefabricated wall sections. Diagonal straps are also used in conventional built-in-place modular walls.
One of the difficulties in providing prefabricated metal wall sections or conventional built-in-place metal walls with strapping is that it is difficult to effectively and efficiently tension the respective straps. First it is difficult to tension the straps manually using conventional tools. Even in cases where a great deal of care and patience is exercised, the straps are not typically fully tensioned, and accordingly, the metal wall, as a whole, lacks the desired rigidity.
Therefore, there has been and continues to be a need for an apparatus and method for efficiently and effectively tensioning and securing wall straps to sections of a metal wall.

Wall strap tensioner for tensioning a wall strap of a metal wall


A backlight unit is provided including a light guide panel (LGP), a point light source emitting light at an edge of the LGP; and a refraction member being positioned between the point light source and the LGP and refracting the light emitted from the point light source toward the optical axis of the point light source in order to reduce the azimuth angle of the light that is incident upon the LGP. The refraction member includes a prism array in which a V-shaped prism pattern is repeatedly arrayed, the apex of the prism pattern facing the edge of the LGP, and a transparent portion that prevents the light from being totally reflected by the prism pattern in a region along an optical axis of the light source.

1. Field of the Invention
The present invention relates to a backlight unit, and more particularly, to an edge light backlight unit using a light guide panel (LGP) and a point light source.
2. Description of the Related Art
In general, flat panel displays are largely classified into light emitting displays and light receiving displays. Light emitting flat displays include elements such as a cathode ray tube, a plasma display, an electron emitting device, and a fluorescent display.
In comparison, a light receiving type flat panel display device (e.g., a liquid crystal display device) forms an image not by emitting light by itself, but by receiving light from the outside. Thus, it is difficult to view an image on such a display device in dark places. Accordingly, a backlight unit for emitting light is installed at a rear surface of the light receiving type flat panel display device. Such a backlight unit has been used in surface light source devices (e.g., an illuminating signboard), as well as light receiving displays (e.g., a liquid crystal display device).
The backlight unit may be either a direct light backlight unit, or an edge light backlight unit, according to the arrangement of light sources thereon. The direct light backlight provides a plurality of lamps directly under an LCD so as to directly illuminate light on a liquid crystal panel. The edge light backlight unit provides lamps at a sidewall of an LGP in order to illuminate light on a side of the LGP and transmit the light to a liquid crystal panel.
More specifically, the edge light type may use a linear light source or a point light source as a light source. Typically, a cold cathode fluorescent lamp (CCFL) is used as the linear light source, while a light emitting diode (LED) is used as the point light source. The CCFL can emit a strong white light with high brightness and high uniformity, and can enable a large size design of a device. However, the CCFL is disadvantageous since it is operated by a high frequency AC signal and has a narrow operational temperature range. In comparison, the LED exhibits a lower brightness and uniformity than the CCFL, but is operated by a DC signal and has a long life span and a wide operational temperature range. Further, the LED can be manufactured therein.
When an LGP is used in an edge light backlight unit, the light output from the linear or point light source is input to an edge of the backlight unit to be incident upon the LGP. The LGP then converts the incident light into a surface light and outputs it in a vertical (i.e., orthogonal to the LGP surface) direction. The LGP is formed of a material having high light transmittance (e.g., an acryl-based transparent resin such as polymethyl methacrylate (PMMA), or an olefin-based transparent resin). A scattering pattern or a hologram pattern is also formed on the LGP so that light, which is input to an edge of the backlight unit and is incident upon the LGP, is output to a light emitting surface.
FIG. 1 is a perspective view of a related art backlight unit of an edge light type using a point light source. FIG. 2 is a cross-sectional view of the edge light backlight unit of FIG. 1. Referring to FIG. 1, three LEDs 20, which are point light sources, are installed at an edge 11 of an LGP 10. A hologram pattern 30 is formed at a rear surface of the LGP 10 in order to emit light input from the LEDs 20 to a light emitting surface 12.
The LEDs 20 emit light toward the edge 11 of the LGP 10. The LEDs 20 are point light sources. Each LED 20 emits light within an azimuth angle of ±90° with respect to an optical axis 21, as shown in FIG. 3. An azimuth angle, at which the intensity of light is half of the maximum value Imax of the light intensity, is called a radiation angle. In the case of an LED, light is emitted at a radiation angle of ±45°.
The light output from the LCDs 20 is incident upon the LGP, passes through the edge 11, 10, and finally, is incident on the hologram pattern 30. The hologram pattern 30 having a diffraction grid structure formed perpendicular to an optical axis 21 changes the incident light to a surface light and makes the surface light proceed through the light emitting surface 12 which is an upper surface of the light guide panel 10.
The hologram pattern 30 can emit light at the highest efficiency when the light is incident on the hologram pattern 30 at an angle of 90°. Also, as the distribution of an incident azimuth angle of the light incident on the hologram pattern 30 decreases, a uniform brightness can be obtained at the light emitting surface 12. If the brightness of the light emitting surface 12 is not uniform, a screen appears to be smeared.
For example, in a narrow range of about 1 cm, a change in brightness of about 0.9 is detected as a smear. However, when the brightness changes gradually from the central portion of the screen to an edge portion thereof, a change in brightness of about 0.8 is not detected as a smear. Thus, a uniformity of brightness over 0.8 is needed. In particular, to obtain a quality image, a uniformity of brightness over 0.9 is needed.
FIG. 4 is a diagram illustrating the distribution of light output from the conventional backlight unit of FIG. 1. The light guide panel 10 is divided into three portions, that is, a near portion 40, a middle potion 50, and a far portion 60, sequentially from the edge 11 where the LEDs 20 are installed. FIG. 4 also shows the distribution of the output of light, and it can be seen that the middle portion 50 and the far portion 60 have a wider light output distribution compared to the near portion 40.
FIG. 5 is a graph showing the brightness at the light emitting surface 12 of the edge light backlight unit shown in FIG. 1. In the graph, the vertical axis indicates brightness and the horizontal axis indicates FWHM (full width half maximum) showing a light emitting angle at the light emitting surface 12. Three curves C1, C2, and C3 from the left side indicate the brightness of the near portion 40, the middle portion 50, and the far portion 60, respectively. Referring to FIG. 5, it can be seen that the brightness of the near portion 40 is greater than those of the middle portion 50 and the far portion 60. The FWHM of the near portion 40 is 20°/20° while those of the middle portion 50 and the far portion 60 are 20°/35° which are relatively wider than that of the near portion 40. In 20°/35°, the first angle "20°" and the second angle "35°" denote FWHMs in an X direction and a Y direction, respectively.
The irregularity of brightness is caused because the distribution of an incident azimuth angle of the light incident on the hologram pattern 30 is different in each of the near portion 40, the middle portion 50, and the far portion 60. Thus, an efficiency of the light emission by the hologram pattern 30 and the distribution of an emitting azimuth angle of the emitting light are different in the three portions. Generally, the larger the azimuth angle of light input to the LGP 10, the more the brightness of the light emitting surface 12 becomes non-uniform.
Such a problem occurs in an LGP having a scattering pattern as well as an LGP having a hologram pattern.


A method of operating a Rake receiver circuit includes determining a first property of a first signal received over a dedicated channel and over a first transmission path. The method further includes determining a delay profile of a second signal and determining, on the basis of the delay profile and the first property, if the first transmission path is to be assigned to a Rake finger of the Rake receiver circuit.

During a communication between components of a radio communications system, signals may propagate from a transmitter to a receiver over different transmission paths. The performance of a receiver may depend on useful energy of received signals and/or noise included in these signals.
Mobile communications transceivers, circuits included therein as well as methods for operating such circuits constantly have to be improved. In particular, it is desirable to improve the reception quality and performance of mobile communications transceivers. For these and further reasons there is a need for the present invention.

Rake receiver circuit and method for operating a rake receiver circuit


In a multi-domain environment, an access control apparatus belonging to a first domain obtains access control information for controlling usage of a function of an image forming apparatus corresponding to a user belonging to the first domain. When the user belonging to the first domain instructs usage of a function of an image forming apparatus belonging to a second domain, the access control apparatus belonging to the first domain requests an access control apparatus belonging to the second domain to add authentication information managed by the second domain to the access control information. The access control apparatus belonging to the first domain transmits access control information including the added authentication information to a client computer.

Field of the Invention
The present invention relates to a printing system capable of flexibly restricting the functions of an image forming apparatus in a multi-domain environment that manages users and office automation (OA) devices belonging to different areas.
Description of the Related Art
As discussed in Japanese Patent Application Laid-Open No. 2003-150336, an access control server issues an access ticket with electronic signature when a user is successfully authenticated in usage of a function of an image forming apparatus. The access ticket includes information relating to a user and various settings (e.g., the number of printable sheets) being set for the user. When the electronic signature of an access ticket is verified, a user can use a print or other function of the image forming apparatus.
In the above-described conventional system, an image forming apparatus managed by the access control server that issues an access ticket is required beforehand to obtain a public key of the server for verification/authentication of an access ticket. In general, each domain in such a multi-domain environment includes a dedicated access control server. When a user of a domain requests a print operation using a printing apparatus belonging to another domain, the user transmits an access ticket issued by a user's access control server to the printing apparatus of another domain.
Therefore, when an image forming apparatus of a domain receives a print request from another domain in a multi-domain environment, the image forming apparatus cannot verify an access ticket issued by a server belonging to another domain and therefore cannot process the received print request. Namely, the above-described conventional system cannot perform a print control according to an access ticket in a multi-domain environment.

This patent is subject to a terminal disclaimer.

Access control apparatus, access control method, and printing system


A method and system providing a vehicle condition detection means (38C) for detecting the stopped and traveling state of a vehicle, and when the vehicle condition detection means (38C) detects that the vehicle has stopped during operation of an exhaust gas temperature raising means (351C), closing an exhaust gas throttling valve (16) in addition to continuing the operation of the exhaust gas temperature raising means (351C), and subsequently, when the vehicle's traveling state is detected, opening the exhaust gas throttling valve (16) and continuing the operation of the exhaust gas temperature raising means (351C). Accordingly, in terms of the regeneration of a continuous regeneration-type DPF device (13) capable of significantly reducing the frequency with which the driver is urged to stop the vehicle and perform forced regeneration, the exhaust gas can be efficiently maintained at a high temperature, and reliable burning of PM is possible even for driving patterns featuring frequent waiting at traffic signals in urban areas, even upon transition to the stationary idling condition during automatic traveling regeneration.

The present invention relates to an exhaust gas purification system that purifies particulate matters (PM) from the exhaust gas discharged by diesel and other internal combustion engines using a continuous regeneration-type diesel particulate filter (DPF) and also to a control method thereof.
In the same way as for NOx, CO, and also HC etc., restrictions on the volume of particulate matters (hereinafter "PM") discharged from diesel internal combustion engines grow severe every year. Techniques for collecting this PM in a filter known as a diesel particulate filter (hereinafter "DPF") and for reducing the quantity thereof by discharging externally have been developed. Continuous regeneration DPF devices represent such.
However, even in continuous regeneration DPF devices, increasing exhaust gas pressure as a result of filter clogging has become a problem. In other words, although the PM collected by these continuous regeneration DPF devices is continuously burned and purified, and the filter will self-regenerate while the exhaust gas temperature is approximately 350° C. or greater, when the exhaust gas temperature is low or the traveling condition of an internal combustion engine has a low NO discharge—for example, when an internal combustion engine has a continuously low exhaust gas temperature accompanied by idling or low load/low speed traveling, etc.—the temperature of the exhaust gas drops and the catalyst becomes inactive as a result of the low temperature thereof. Accordingly, as the oxidization reaction does not progress and NO becomes insufficient, the above-described reaction does not take place, and the filter does not regenerate by oxidizing the PM. Accordingly, the accumulation of PM in the filter continues and clogging thereof is accelerated.
Countermeasures for clogging of the filter such as those described below are disclosed in Japanese patent application Kokai publications No. 2002-276340 and No. 2003-206723. Before clogging of the filter has exceeded a predetermined level using methods for detecting the differential pressure before and behind the filter etc. has been detected, if the exhaust gas temperature is lower than the active temperature of the oxidation catalyst provided upstream of the filter or the oxidation filter supported on the catalyst, exhaust gas temperature is forcibly raised and the collected PM then forcibly removed through being burned.
Furthermore, injection control within the cylinders can be used as a means for raising the exhaust gas temperature. In accordance with this method, multi-step injection is carried out and the exhaust gas temperature is raised; post injection is carried out when the temperature thereof has risen beyond the active temperature of the oxidation catalyst; and any unburned fuel contained in the exhaust gas is burned in the oxidation catalyst. As a result of this burning, the exhaust gas temperature is raised beyond the temperature of burning temperature of the PM collected in the filter, and the collected PM removed through the burning thereof, thus regenerating the filter.
Normally with continuous regeneration DPF devices, when the collected quantity of PM reaches a preset limit, the traveling condition of the internal combustion engine is automatically changed to regeneration mode. In this forced regeneration mode operation, the exhaust gas temperature is forcibly raised and the quantity of NOx is increased. And thereby, the collected PM is oxidized and removed from the filter to regenerate the filter.
Furthermore, Japanese patent application Kokai publication No. 2003-155914 proposes an operating means whereby, an actuation means such as a forced regeneration means which can be actuated arbitrarily when a large quantity of particulate matters (PM) has accumulated in the diesel particulate filter (DPF) by some reasons, the driver can intentionally and immediately carry out the forced regeneration of the particulate filter. More specifically, this actuation means is comprised of a warning light that indicates excessive collecting condition and a regeneration button in the vicinity of the driver's seat so that forced regeneration can be arbitrarily controlled.
Furthermore, Japanese patent application Kokai publication No. 2003-155914 proposes to indicate a warning to carry out a human-initiated forced regeneration in which the collected particulate matters are forcibly burned and removed when it is judged that the particulate filter has become clogged upon a confirmation of an abnormal increase in back pressure based on the differential pressure before and behind the particulate filter.
In order to address the problem of oil dilution upon forced regeneration while traveling and the problem of uneven accumulating around the outer surface of the PM filter, a regeneration control method comprised of a combination of manual regeneration and traveling automatic regeneration in response to a travel distance is under consideration.
In terms of oil dilution, it is undesirable that forced regenerating processing be too frequently carried out. If forced regenerating processing is carried out while the vehicle is being traveled, the engine speed will be high in comparison with that of stationary idling; accordingly, it is inevitable that post injection volume increases with a result that the degree of diluting of oil by fuel increases. In particular, a post injection control becomes difficult during transient condition. In other words, even if the engine temperature is raised in a transient condition resulting from load variation, post injection is performed wastefully. It is difficult to avoid this type of wasteful injection. And furthermore, if left unaddressed, oil dilution can lead to the problems of excessive wear or scorching of the moving mechanical components.
In contrast, the forced regeneration control does not cause such problems in a stationary condition of the vehicle and the degree of oil dilution relatively insignificant. As a result, the forced regeneration control is not carried out while the vehicle is being traveled, but after it has stopped traveling.
In other words, when the operating condition is in a stabilized mode such as an idling condition while the vehicle is stationary, the post injection of fuel injection into the cylinder is carried out with an injection quantity corresponding to a load less than that necessary for normal vehicle traveling. As a result, forced regeneration is carried out by raising of the exhaust gas temperature, and oil dilution can be reduced to a level lower than that corresponding to regeneration control while the vehicle is being traveled.
One method thereof is disclosed as follows in Japanese patent application Kokai publication No. 2003-155914. When the filter reaches a preset level of clogging, the driver is notified of the need to carry out forced regeneration using a lamp or such like, and after stopping the vehicle upon receiving of this notification, the driver operates a manual regeneration switch provided in the vicinity of the driver's seat to perform forced regeneration control and filter regeneration.
Furthermore, since a vehicle has a wide range of traveling patterns, problematic clogging unrelated to differential pressure and resulting from uneven loading of PM can also occur. For example, there are many occasions on which vehicles are frequently traveled on high-speed motorways and at high-speed with high-load, and since the exhaust gas temperature is also high, forced regeneration control is not carried out and self-regeneration is urged. However, PM does not accumulate at the center of the filter, and uneven accumulating—in other words, accumulation in a circular pattern around the outside thereof—occurs. And when PM burning starts in such a case during forced regeneration carried out after uneven accumulating, this uneven PM accumulation is all burned at essentially the same time and in a rapidly expanding pattern. As a result, extremely high temperatures occur within the interior of the filter. And this runaway burn is a cause of the DPF melting.
The problem of oil dilution becomes less frequent when a sufficiently long distance is traveled as fuel mixed into the oil evaporates. Accordingly, a combination of forced regeneration by multi-step injection and post injection is adopted for forced regeneration in response to a manual regeneration switch being operated when the travel distance has exceeded a predetermined travel distance and the exhaust gas temperature is low even if the vehicle is being currently traveled.
Furthermore, in the case of vehicles often driven by low-speed/high-load traveling patterns, flashing of the lamp to notify the driver the need of manual regeneration is so frequent that the driver feels it troublesome. In order to avoid this problem, the low collecting exhaust gas temperature raising control is carried out to raise the exhaust gas temperature by temporary control of fuel injection into the cylinder without an Unburned fuel supply control by post injection—the vehicle can be traveled until it has reached the distance at which the fuel mixed into the oil evaporates and regeneration during traveling is possible.
A first temperature raising judgment collecting quantity, which is less than the judgment collecting quantity corresponding to the notification of a manual regeneration request, and a second temperature raising judgment collecting quantity, which is less than the first temperature raising judgment collecting quantity, are provided for this low collecting quantity-time exhaust gas temperature raising control. The low-collecting quantity-time exhaust gas temperature raising control operates when the detected collecting quantity has exceeded the first temperature raising judgment collecting quantity, and thereafter, it is interrupted when the detected collecting quantity has fallen below the second temperature raising judgment collecting quantity.
Nevertheless, vehicles are actually traveled in a wide range of different traveling conditions. In particular, in such a place like an urban area, traveling and stopping are frequently repeated because of traffic signals and the like. This repetition makes engine load varies between traveling condition and stationary idling condition in a complicated manner. Consequently, the exhaust gas temperature also varies in a complicated manner.
In other words, in the case low collecting quantity-time exhaust gas temperature raising control is carried out using multi injection, when engine condition changes from traveling condition to stationary idling condition, the exhaust gas temperature raised during traveling of the vehicle drops as a result of factors such as reduced flow of exhaust gas when the vehicle stops. Furthermore, since the engine load in stationary idling is low, the combustion condition upon multi injection is not stable when low collecting quantity-time exhaust gas temperature raising control continues to be active, and as a result, exhaust gas temperature raising is not possible.
For this reason, different traveling patterns can cause problems such that unburned fuel ultimately turns into white smoke to be discharged to the atmosphere and fuel efficiency deteriorates. That is to say, it is possible that DPF regenerating control will not terminate within the preset time, that it will not be possible to sufficiently raise the exhaust gas temperature, and that the collected PM will not be burned and removed sufficiently. Furthermore, since the combustion condition is not stable, not all of the injected fuel is burned within each cylinder, and in addition, since the exhaust gas temperature is low, this unburned fuel is not oxidized by the action of the oxidation catalyst and flows therefrom into exhaust duct can occur.
In addition, as the exhaust gas temperature drops while the vehicle is in the stationary idling condition, even when traveling thereof restarts, a certain period of time is required until the exhaust gas temperature is raised to where self-regeneration of the DPF is accelerated, the time required for execution of low collecting quantity-time exhaust gas temperature raising control using multi injection becomes longer, and this causes a problem of impaired fuel efficiency.

Control method for an exhaust gas purification system and an exhaust gas purification system


A method for designing a distributed communication topology of a micro-grid based on network mirroring and global propagation rates includes the following steps: first, determining the communication connectivity of distributed directed networks in the micro-grid; next, obtaining, for connected directed communication networks, mirror networks thereof based on a mirroring operation, and selecting an optimal distributed directed communication topology corresponding to a maximum performance indicator based on algebraic connectivity and communication costs; solving, for the optimized distributed communication topology, pinned distributed generation sets corresponding to different pinning numbers based on global propagation rates and out-degrees; and finally, establishing a distributed secondary voltage control of the micro-grid based on the optimal distributed communication network and pinned nodes of the micro-grid, to achieve accurate reactive power sharing and average voltage restoration.

With the exhaustion of earth resources and people's attention to environmental issues, access of renewable energy resources is increasingly valued by countries around the world. The micro-grid is an emerging energy transmission mode that increases the permeability of renewable energy resources and distributed energy resources in energy supply systems. The micro-grid includes different types of distributed energy resources (DERs, including micro gas turbines, wind driven generators, photovoltaics, fuel cells, energy storage equipment, etc.), user terminals of various electrical loads and/or thermal loads and related monitoring and protection devices.
The energy conversion of the internal power sources of micro-grid mainly lies in power electronic devices, which also provide necessary control; the micro-grid is a single controlled unit with respect to an external grid, and can meet the requirements of users for power quality, power supply security and the like at the same time. The energy is exchanged between the micro-grid and the main grid through a point of common coupling, and the two are mutually standby, thus enhancing the reliability of power supply. Since the micro-grid is a small-scale decentralized system and is close to the load, it can increase the reliability of local power source, reduce the network loss and greatly increase the energy utilization efficiency, and is a new power supply mode that meets the requirements of future smart grid development.
Under normal circumstances, the micro-grid operates in grid-connected mode, and is supported by the main grid in voltage and frequency. When an emergency or planned event causes the micro-grid to be off-grid, the micro-grid will work in an autonomous state. The droop control strategy has gained wide attention because it does not require the communication between distributed generations. When the micro-grid needs to be switched from the grid-connected mode to the islanding mode, each distributed generation can automatically share the load power in the micro-grid. However, the droop control will cause a steady-state deviation of the voltage due to its intrinsic properties, and the effect of reactive power sharing is not ideal considering the diversity of output impedances of different distributed generations. Therefore, secondary cooperative control is required to assist voltage recovery and appropriate reactive power allocation. The consensus theory is an effective way to realize cooperative control. In large-scale systems, considering factors such as communication cost and network complexity, a directed distributed communication topology based on pinning consensus has been widely used. With the development of open communication modes, especially wireless communication, communication topology design has become the focus of distributed secondary control. In order to reduce communication cost and improve system convergence performance, it is necessary to optimize the design of the directed communication topology and the pinned distributed generation set to improve the dynamic performance of the system.

Method for designing distributed communication topology of micro-grid based on network mirroring and global propagation rates


A solar distillation loop apparatus includes a first pipe section disposed on a ground surface, the first pipe section including a substantially straight portion and elevated portions on each end of the substantially straight portion, an impure water inflow coupling at one end of the straight portion and an impure water outflow coupling at the other end of the straight portion; solar powered fans disposed in each of the elevated portions of the first pipe section; a second pipe section disposed under the ground surface beneath the first pipe section; and two substantially vertical pipe sections that connect respective ends of the second pipe section to respective ends of the first pipe section.

The invention relates in general to the purification of water and in particular to the purification of water using solar energy.
At present, agricultural expansion into many semi-arid and arid regions is severely limited by the scarcity of good quality irrigation water and the cost of the energy necessary to provide irrigation to these areas. Generally, although water resources remain available to these regions, they are mostly unexploited due to two main factors: (1) unacceptable quality of the water for irrigation (e.g., water high in salts or toxins); and (2) the requirement of great conveyance energy (i.e., water transportation, pumping, and pressurizing energy) in order to approach economic usefulness. Due to increased competition for good quality water and higher conveyance costs, the total cost of irrigation is continually increasing in such areas. If this trend continues, not only will agricultural expansion be curtailed, but substantial reductions in irrigated agriculture may be necessary.
Another problem in these dry regions arises with regard to salt accumulation in agricultural basins. For many agricultural basins associated with irrigated areas, irrigation drainage water has become a severe environmental pollutant. This is primarily due to the leachates and tailwaters of the drainage which cause increased salinity of groundwater and surface water resources. Since water imports are limited to their present levels in most of these basins, there have been gradual increases in the proportion of impaired water resources to good quality water resources in these basins.
As a consequence of the situation described above, methods for improving irrigation management, water conservation, and saline water conversion have become increasingly active areas of water resources research. Irrigation management has been improved through more precise irrigation scheduling and increased use of drainage systems. In addition, water conservation techniques such as installation of drip (trickle) irrigation systems and the adoption of drought tolerant crops have helped to maintain the present level of irrigated agriculture in semi-arid and arid regions while leading to reductions in the amount of agricultural drainage. However, when the only water resources available are saline or otherwise impaired, irrigation management and water conservation methods become ineffective, necessitating alternatives such as the use of salt tolerant crops or saline water conversion processes. Although there has been some success with a limited number of salt tolerant crops, water conversion and purification techniques are not being used extensively because of the high costs involved. At present, there are ever increasing amounts of impaired water resources in arid and semi-arid regions that cannot be used for irrigation, and the problem of water distribution in these areas is becoming a very serious one.
In light of these trends, there exists a clear need for a low-energy inexpensive process for water purification and irrigation which is designed to help solve the complex problems associated with water scarcity, increasing water conveyance costs, and regional accumulation of salts. It would be desirable, therefore, to develop an apparatus and process which can cheaply and effectively purify saline or otherwise impaired water resources, and at the same time, distribute the purified water to row crops to allow them to grow in arid and semi-arid regions.

The United States of America as represented by the Secretary of the Interior


An information processing device (20) performs a session timer updating process of restoring the remaining time of a session timer to N seconds whenever a packet is received from a client (10). The information processing device (20) does not perform the session timer updating process even when a packet is received from the client (10) until a session timer update stop time (Δ) elapses after the session timer was last updated. The information processing device (20) resumes the session timer updating process after the session timer update stop time (Δ) has elapsed after the session timer was last updated.

Many servers and stateful network devices (hereinafter collectively referred to as "network devices") have a session table for managing connections such as TCP (Transmission Control Protocol).
A network device having the session table holds session information of communication with a communication counterpart device (for example, a client) in the session table until a time set in a session timer elapses in preparation for unexpected communication disconnection (for example, no FIN is returned) from the communication counterpart device. After the time set in the session timer elapses, the network device deletes the session information of the communication from the session table.
Here, the network device resets (extends) a session timer whenever a packet is received from the communication counterpart device in preparation for prolonged communication with the communication counterpart device. In this way, the network device can continue communication with the communication counterpart device even when the communication time with the communication counterpart device exceeds the time set in the session timer.
This will be described with reference to FIG. 5. In this example, a case in which a network device including a session table is a server and a communication counterpart device of the network device is a client will be described.
For example, as illustrated in FIG. 5, when a server receives a syn packet of TCP from a client and starts communication, the server registers session information in a session table and sets a session timer. For example, a prescribed timeout period (for example, N seconds) is set in the session timer. After that, the server exchanges some kind of communication with the client and deletes the session information of the communication from the session table when a remaining time indicated by the session timer reaches zero. Here, when the server was still communicating with the client, since the session information was deleted from the session table, the server cannot communicate with the client.
Therefore, as illustrated in FIG. 6, after the server starts communication with the client, registers session information in a session table, and sets a session timer, when a packet is received from the client, the server updates the session timer. For example, the server restores a remaining time indicated by the session timer to a prescribed time (for example, N seconds) whenever a packet is received from the client. With this process, even when communication between the server and the client is prolonged, since the session timer is updated (extended), the server can communicate with the client.

Information processing device and method for updating a session timer

NIPPON TELEGRAPH AND TELEPHONE CORPORATION


Transparent ohmic contacts to p-GaN and other high-work-function (≧4.2 eV) semiconductors are fabricated from zinc stannate (e.g., ZnSnO3). ZnO and SnO2 may be sputtered from separate targets and annealed to form the zinc stannate. The Zn:Sn ratio may be tuned over the range between 1:2 and 2:1 to optimize bandgap, work function, conductivity, and transparency for the particular semiconductor and wavelength of interest. Conductivity may be improved by crystallizing the zinc stannate, by doping with up to 5 wt % Al or In, or both.

Related fields include transparent conductive thin films, particularly for use with optoelectronic devices including III-V materials, and physical vapor deposition (PVD), particularly sputtering.
A typical LED emits light from an active photoemissive semiconductor layer sandwiched between p-type and n-type semiconductor layers. Electroluminescence results when negative charge carriers (electrons) from the n-type layer and positive charge carriers ("holes") from the p-type layer meet and combine in the active photoemissive layer.
The wavelength and color of the emitted light depends, at least in part, on the semiconductor bandgap. For example, arsenides of aluminum (Al), gallium (Ga), indium (In), and their alloys emit red and infrared light; phosphides of Al, Ga, In, and their alloys emit green, yellow, or red light; and nitrides of Al, Ga, In, and their alloys emit ultraviolet, violet, blue, or green light. These "III-V materials," so-called because they include elements from old group III (now group 13) and old group V (now group 15) of the periodic table, have high carrier mobility and direct bandgaps that are desirable in optoelectronic applications. However, substrates made of III-V materials have historically been very expensive. GaN and AlN substrates are becoming increasingly available, but problems with instability and defects persist. A common alternative approach has been to grow III-V layers by epitaxy on a different substrate material such as sapphire (Al2O3), silicon (Si), silicon carbide (SiC), germanium (Ge), zinc oxide (ZnO), or glass.
A "junction-up" LED emits its output light in a direction pointing away from the substrate, while an inverted, or "flip-chip," LED emits its output light toward the substrate. Both types may use transparent electrodes on the light-emitting side to facilitate the passage of both electrical current and light through the semiconductor stack. Other devices with similar requirements for current and light traversing the same surface also use transparent electrodes. Many thin-film materials for transparent electrodes are oxides, and are generically known as "transparent conductive oxides" (TCO).
Indium tin oxide, (ITO), the most common TCO material for transparent electrodes, is expensive because it is typically over 90% indium (In). The optical transparency and the conductivity generally need to be traded off against each other because the highest-transparency formulations are generally different from the highest-conductivity formulations. In addition, both the optical transparency and the conductivity may be unstable with temperature, and therefore may change unpredictably during high-temperature process steps, such as annealing, that may be required to fabricate either the TCO itself or other parts of the device.
As with any electrode material, another variable that needs to be optimized is the work function. If a low-loss ohmic contact to a semiconductor is desired, a generally necessary (though not always sufficient) condition is a close match between the electrode work function and the semiconductor work function. High-indium ITO is one of a few TCO materials that can be tuned to match the work function of p-GaN.
Therefore, a need exists for a cost-effective TCO material with a work-function matching that of p-GaN (4.2 eV or greater), exhibiting low absorption coefficient (<0.03%/nm) and low resistivity (contact resistance<0.005 Ω-cm2) throughout the temperature range of fabrication processes for LEDs and other optoelectronic devices. Smooth morphology and compatibility with other processes used in making the device are also desirable.

Zinc stannate ohmic contacts for p-type gallium nitride


A ceiling structure includes a suspended framework having a plurality of main runners and a plurality of cross runners interconnected to define an array of tile receiving openings and a plurality of ceiling tiles positioned within the array of tile receiving openings, each of the plurality of ceiling tiles having a plurality of magnets positioned at a peripheral portion thereof which are configured to magnetically couple the ceiling tile within a respective one of the tile receiving openings with the ceiling tile abutting a respective mounting frame. Related methods are also provided.

1. Technical Field
The present disclosure relates to ceiling structures, and more particularly, to ceiling tiles for constructing a ceiling structure, and systems and methods for assembling the same.
2. Description of the Related Art
Conventional suspended ceiling structures are constructed by assembling a ceiling structure grid above a floor and at the upper end of walls that form a boundary around residential or commercial space. The ceiling structure grid primarily includes a plurality of main runners and cross runners, which may be suspended by wires or the like from the overhead structure above. The pluralities of main runners and cross runners are generally oriented to be perpendicular to each other. The plurality of main runners and cross runners are each spatially spaced apart and interconnect at positions of intersection, which defines an opening to receive ceiling tiles. Conventional ceiling tiles are positioned within such openings from above and rest on the grid in a non-secured manner. Construction and assembly of such conventional suspended ceiling structures can be complicated, time consuming, laborious, and may not result in an aesthetically pleasing ceiling.


A method of synthesizing R1, R2-substituted-4′ (ax. or eq.)-OH anthracyclines and their corresponding salts of Formula (1) from daunorubicin or N-Trifluoroacetyl-4-R1-derivatives of daunorubicin, wherein R1 is defined as H, OH, and 4′-HO is defined as ax[ial]. The method includes producing N-Trifluoroacetyl daunorubicin and treating the N-Trifluoroacetyldaunorubicin or N-Trifluoroacetyl-4-R1-derivatives of daunorubicin, wherein R1 is defined as H, OH, with dimethylsulfoxide activated by different acylating agents. The attained intermediate product is then treated with a strong base (ex. tertiary amines) resulting in the 4′-keto-N-Trifluoroacetyl-4-R1 daunorubicin wherein R1 is defined as H, OH, OMe. The 4′-keto-N-Trifluoroacetyl-4-R1-daunorubicin is reacted with a reducing agent, a derivative of a borohydride of an alkaline metal MHBL3 , to produce N-Trifluoroacetyl-4′-epi-4-R1-daunorubicin. The N-Trifluoroacetyl-4′-epi-4-R1-daunorubicin undergoes hydrolysis in a basic solution to produce a derivate of an anthoacyclin which is halogenized [by complex halogenides] to form a 14-Hal-derivative. This result is then hydrolyzed by well-known methods in the presence of a formate of an alkaline metal to form the desired final compound.

Anthracyclines form one of the largest families of naturally occurring bioactive compounds. Several members of this family have shown to be clinically effective anti-neoplastic agents. These include, for example, daunorubicin, doxorubicin, idarubicin, epirubicin, pirarubicin, zorubicin, aclarubicin, and carminomycin. For instance, these compounds have been shown to be useful in bone marrow transplantation, stem cell transplantation, treatment of breast carcinoma, acute lymphocytic and non-lymphocytic leukemia, chronic lymphocytic leukemia, non-Hodgkin's lymphoma, and other solid neoplasias.
The most common starting material, utilized for synthesis of semi-synthetic derivatives of anthracyclins, is Daunorubicin. In Daunorubicin, the 4′-hydroxyl group of aminoglycoside fragment is in axial configuration. For production of epi-derivatives, it is necessary to change the configuration of this hydroxyl group from axial to equatorial. This can be attained in two ways: oxidation of the 4′-OH group to ketone (with loss of an optical center) with further stereospecific reduction to the required equatorial configuration [1]; or biomolecular nucleophilic substitution of 4′-OTf—derivative, accompanied by Walden inversion and, hence, by epimerization [2]. These modifications can be accomplished both on intact anthracyclin molecules and on isolated aminosugars, derived as a result of algycone removal [3] or separately synthesized [4]. Simplicity of working with isolated aminosugar is countered by difficulty of a stereospecific reaction of aglycone glycosilation. In this situation, more times than not, the real yield of the required α-anomer of anthracyclin appears to be less than those previously declared [3,4,5].
Modification of 14-R2═H to 14-R2═OH is conducted by halogenization of the end methyl group with molecular bromine or iodine at room or lower (6-10° C.) temperature in a mixture of anhydrous methanol and dioxane [6]. Earlier patents described bromination of the unprotected ketone group; afterwards, ketone protection the 13-C═O group was demonstrated [7]. Next, the halogen undergoes nucleophilic substitution with hydroxyl or a carboxylate anion with creation of an intermediate ester 14-R2═OCOAlk (Ar), where, most commonly, R2═OCOH. This ester is then hydrolyzed to 14-R2═OH.
The described methods, especially those that require glycosilation stage, require utilization of a significant number of protection groups in order to provide an adequate modification of anthracyclin molecule. Placement and removal of protection groups significantly increases the number of synthetic stages, and decreases the yield of the product. The subject of the present patent is decrease in the number of stages of the synthetic process and increase in the selectivity of the chemical reactions, including stereospecificity, during synthesis both currently-known and future novel anthracyclins.

Epimerization of 4′-C bond and modification of 14-CH


Methods and apparatus for monitoring and controlling the operation of a refrigeration unit in a manner which eliminates the need for circuit breakers and fuses in control circuits which are instrumental in selecting and changing the operational mode of the refrigeration unit. When a need to change to a different operating mode is detected, a controller energizes a control device associated with the different operating mode and quickly determines if the current draw is within an acceptable range. If the current draw is within an acceptable range or window, the controller initiates the requested different operating mode. If the current draw is not within the acceptable range, the controller generates an appropriate alarm and different courses of action are decided upon which depend upon whether the current draw is above or below the limits of the acceptable range, the nature of the requested operating mode, and the desired temperature of a space conditioned by the refrigeration unit.

U.S. Pat. No. 4,663,725, which is assigned to the same assignee as the present application, discloses the use of microprocessor based transport refrigeration control for use with a refrigerated container, with the refrigerant compressor being driven by an electric motor. This patent is directed primarily to the use of a microprocessor to operate the various components of the refrigeration system according to predetermined algorithms, and to detect and record faults which occur during the operation thereof.
U.S. Pat. No. 4,918,932, which is assigned to the same assignee as the present application, discloses the use of a microprocessor to determine average error between an operator selected set point temperature and the temperature of a space to be conditioned, using the outputs of return air and discharge air sensors, and the use of the average error in the determination of an error signal which modulates the capacity of the system.
Our U.S. Pat. No. 5,140,825, which is assigned to the same assignee as the present application, discloses a method which checks electrical components and wiring of a microprocessor controlled refrigeration system by using a battery and a current shunt which measures battery current. All checking is accomplished with a refrigerant prime mover off, so that an alternator driven thereby will not affect battery draw current. Each electrical component to be checked is automatically successively connected and disconnected from the battery, the current draw is compared with appropriate current draw limits, and an alarm is provided when the current draw is outside the draw limits.
It would be desirable, and it is an object of the invention to be able to monitor current draw of a refrigeration unit while it is operating, which, along with the teachings in our aforesaid patent, will provide complete protection for a refrigeration unit.
Refrigeration control systems of which we are aware utilize circuit breakers and fuses to isolate faulty components. Circuit breakers and fuses often result in unnecessarily shutting down the associated refrigeration unit when it is still capable of preserving a conditioned load, and circuit breakers and fuses add component and assembly cost to a refrigeration unit. It would be desirable, and it is another object of the present invention, to eliminate the need for circuit breakers and fuses in critical control areas of a refrigeration system.

Method and apparatus for monitoring and controlling the operation of a refrigeration unit


A direct digital synthesizer circuit and method for reducing the harmonic content in a synthesized output signal. The direct digital synthesizer generates first and second address signals driving first and second sine look-up read only memory (sine ROM) circuits. The first and second sine ROMs generate first and second digital sine wave signals which are offset in phase from one another by 180 degrees. The first and second digital sine wave signals are converted to first and second analog sine wave signals. The first and second analog sine wave signals are combined in a subtractor circuit. As a result of the phase relationship between the first and second analog sine wave signals, the fundamental component of these signals are emphasized by subtraction while the second harmonic component of theses signals are simultaneously de-emphasized.

1. Field of the Invention
The present invention relates generally to direct digital synthesizers, and more particularly relates to a circuit and method for reducing the harmonic content of signals generated by a direct digital synthesizer.
2. Description of the Prior Art
Direct digital synthesizers (DDS) are well known in the prior art. The block diagram of FIG. 1 illustrates the topology of a known DDS. The DDS of FIG. 1 is capable of generating a sine wave signal with precise control over the phase and frequency of that signal.
Referring to FIG. 1, the DDS includes a frequency value register 2. The frequency value register 2 is operatively coupled to an external digital controller 4, such as a microprocessor. The external controller 4 provides required frequency and phase value information to the DDS. The DDS further includes a phase accumulator circuit 6. The phase accumulator 6 is essentially a counter circuit which cycles between zero and a final value determined by the frequency value received from the frequency register 2 in response to a received DDS phase clock signal.
The phase accumulator 6 generates an address signal which is illustrated in FIG. 2. The address signal is composed of a number of output states which represent equivalent phase values of the DDS output signal. The DDS further includes a sine look-up read only memory (sine ROM) circuit 8. The sine ROM 8 receives the address signal from the phase accumulator 6 and generates a digital sine wave signal in response thereto. The digital sine wave signal is illustrated in FIG. 3. It will be appreciated that while the diagrams of FIGS. 2 and 3 are illustrated graphically, these signals are actually composed of discrete digital values.
The DDS further employs a digital to analog convertor (D/A) 10 to generate an analog sine wave signal. The D/A 10 is responsive to the digital sine wave signal from the sine ROM 8 and generates a corresponding analog sine wave signal.
Because of the discrete nature of the digital sine wave signal and inherent non-linearities associated with the D/A 10, the resulting analog output signal from a conventional DDS is typically rich in harmonic content. Typically, the second harmonic (twice the desired signal frequency) is especially strong.
To eliminate the harmonics from the desired fundamental output signal, a DDS would typically rely on analog filtering techniques. However, given the broadband nature of the DDS, it is often difficult to optimize the filter parameters of a fixed analog filter to properly reduce the harmonics over the full operating frequency range of a DDS. Further, to achieve significant harmonic attenuation, a filter with many poles is required. This filter topology typically introduces signal loss to the desired signal.
As an alternative to conventional filtering, it is also known in the art that discrete signal components, such as harmonics, may be reduced by analog phase cancellation. The block diagram of FIG. 4 illustrates a simplified phase cancellation circuit. Referring to FIG. 4, an input signal including both a desired frequency component and an undesired frequency component is applied to a broad band power divider 11. The power divider 11 equally splits the power of both the desired and undesired signals into two outputs. One output of the power divider 11 is coupled to a narrow band analog phase shift network 12. The phase shift network 12 is designed to provide 0.degree. phase shift to the desired signal and 180.degree. phase shift to the undesired signal.
The second output of the power divider 11 is coupled to an attenuator 14. The attenuator 14 is selected to provide equivalent signal loss to that of the phase shift network 12 at the undesired frequency. In this way, the output level of the undesired frequency component is equal at both the attenuator 14 and phase shift network 12 outputs. These outputs are operatively coupled to a power combiner (adder) 16. The power combiner 16 reinforces in-phase signals and cancels out-of-phase signals. Therefore, the output of the power combiner 16 will feature a slightly reduced desired signal (inherent circuit losses) and a significantly reduced undesired signal level.
Analog phase cancellation has many disadvantages. The analog phase shifter 12 is a narrow bandwidth device. Therefore, the analog phase shift network 12 is difficult to manufacture (tuning adjustments often required) and is only usable over a limited frequency range. Also, the analog phase cancellation circuit often attenuates the desired signal. To overcome these signal loses, additional amplifiers are typically required.

Apparatus and method for harmonic reduction in a direct digital synthesizer


A multi-speed transmission having drive and output shafts, front-mounted planetary gearsets, rear-mounted planetary gearsets and six shift elements. Selective engagement of shift elements selectively renders a drive shaft speed and speeds generated in the front gearsets for achieving a reverse gear and twelve forward gears via the rear gearsets transmissible as an output speed to the output shaft. Four shift elements are assigned to the front gearsets and two are assigned to the rear gearsets. At least one front gearset is rigidly connected to an element of the rear gearsets, resulting in six different output speeds of the front gearsets being transmissible to the rear gearsets. If normalized to the drive shaft input speed, one output speed is smaller than 0, three output speeds are between 0 and 1, one output speed is equal to 1 and one output speed is greater than 1.

For instance from document EP 1 373 756 B1, a multi-speed transmission is known as an automatic transmission, in which, for instance, two front-mounted gear sets and two rear-mounted gear sets are provided, to which seven shift elements are assigned, wherein, however, only eleven forward gears and one reverse gear can be achieved. A connecting shaft is used to permanently connect the front-mounted gear sets to the rear-mounted gear sets. Further, the rear-mounted gear sets can be connected to the drive shaft via a shaft and a clutch as a shift element and can be fixed via a further shaft and a brake as a further shift element, such that the two rear-mounted gear sets in at least three of the forward gears simultaneously transfer torque. For that reason, the number of gears is limited in spite of the large number of components required, such as the seven shift elements.


A miniature time-of-flight mass spectrometer (TOF-MS) and method for increasing the collection efficiency of laser-desorbed ions in a miniature time-of-flight mass spectrometer (TOF-MS) is provided. The method provides a laser pulse generated by an ionization extraction device within the TOF-MS; maintains a sample plate potential at a ground level for a fixed delay period of about 50 ns; and uses a high voltage switch to sharply increase the sample plate potential up to 10 kV/mm.

1. Field of the Invention
The present invention generally relates to miniature time-of-flight mass spectrometers (TOF-MS) for improving resolution and mass range employing an impulse extraction ion source and methods for its use.
2. Description of the Related Art
Miniature time-of-flight mass spectrometers (TOF-MS) have the potential to be used in numerous field-portable and remote sampling applications due to their inherent simplicity and potential for ruggedization. However, these miniature time-of-flight mass spectrometers traditionally suffer from low mass resolution due to the reduced drift length of the analyzer. Attempts have been made to recover this reduction in mass resolution, by using, for example, ion reflectors. Typically, though, ion reflectors exhibit a limited useful mass range, typically less than 5 kDa. While this range is useful for many biological agents, a much wider mass range is required to detect intact proteins and numerous biological warfare agents. To this end, several forms of "pulsed extraction (PE)" or "delayed extraction" techniques have been developed to reduce the peak widths of ions detected in the TOF analyzer. These methods, however, improve the resolution for only a fraction of the total mass spectrum for any given delay setting thereby requiring the TOF analyzer to be scanned in order to achieve good resolution across a broad mass range.
A need therefore exists for an apparatus and method that does not require the TOF analyzer to be scanned in order to achieve good resolution across a broad mass range.

Time- of flight mass spectrometers for improving resolution and mass employing an impulse extraction ion source