Described are systems and methods for executing a pipeline command sequence designed for execution on a single node across a fleet of nodes. An example method may commence with receiving the pipeline command sequence. Based on a type of the pipeline command sequence, a subset of available nodes for optimal execution of the pipeline command sequence across the fleet of nodes may be determined. The method may continue with defining a plurality of tasks for the subset of available nodes. The method may further include translating the pipeline command sequence into the plurality of tasks and executing the plurality of tasks on the subset of available nodes.

Customers of network systems and services expect their systems to be running and perform consistently. Jitter, downtime, and even maintenance windows in performance are no longer acceptable. Customers run their systems around the clock and expect them to run without any interruptions or performance loss. A customer may want to define a task as a simple pipeline command designed for execution on a single machine. However, the task may require resources and data going beyond the ability of the machine. Currently, there is no transparent way to translate a pipeline command into a plurality of tasks for execution across a fleet of nodes.

Executing a pipeline command sequence designed for execution on a single node across a fleet of nodes


Described are techniques for predictive regression testing. The techniques include a method comprising constructing a call graph of a modified codebase including at least one modified node corresponding to a modified function. The method further comprises generating a subset of codebase tests by removing respective codebase tests that do not call for the at least one modified node. The method further comprises generating respective partial Abstract Syntax Trees (AST) sequences for relevant test paths in the call graph that connect the at least one modified node to one of the subset of codebase tests. The method further comprises inputting, to a machine learning model, the respective partial AST sequences, and generating, based on output from the machine learning model, predicted regression testing results for the relevant test paths.

The present disclosure relates to regression testing, and, more specifically, to predictive regression testing.
Regression testing includes running functional and/or non-functional tests to ensure that updated software still runs appropriately. A test failure on a new version of software as a result of updates to the software can be referred to as a regression. Regression testing can be performed during initial software development and/or during software maintenance such as software updates (e.g., bug fixes, configuration changes, software improvements, etc.).

Regression prediction in software development

International Business Machines Corporation


A gas analysis device includes a laser light source configured to output a laser beam, an irradiation unit configured to irradiate a measurement region including measurement target gas with the laser beams in plural directions, plural photoreceivers each configured to receive a laser beam having passed through the measurement region and output an electric signal according to intensity of the received laser beam, and an analyzer configured to analyze the physical state of the measurement target gas based on the electric signal output from each photoreceiver. The analyzer sets a function (e.g. two-dimensional polynomial f(X,Y)) representing the physical state (e.g. concentration, temperature) of the target gas at least in the measurement region, and measures the physical state of the target gas by determining a coefficient of each of terms included in the function based on a measured value obtained from the electric signal output from the photoreceiver.

Recently, interest on global environment conservation and effective energy use has been growing in various fields to prevent global warming, fossil fuel depletion, environmental contamination, and the like, and thus various kinds of environmental technologies have been researched.
In such environmental technologies, it is important to understand a combustion structure of a combustion phenomenon in an engine, a burner, or the like, and transitional behavior thereof in detail. Recently, measurement technologies utilizing a semiconductor laser absorption spectroscopy have been developed as means for measuring temperature and concentration distributions of combustion gas in a highly responsive and temporally sequential manner.
Typically, an absorption spectroscopy is a measurement method utilizing property that gas molecules absorb infrared light having a wavelength unique to a chemical species, and temperature and concentration dependency of the amount of absorption. The concentration and temperature of an absorption medium (target gas) having a uniform optical path length can be measured by obtaining the ratio (Iλ/Iλ0) of the intensity (Iλ0) of incident light to the intensity of transmitted light (Iλ) having passed through the target gas.
The technology disclosed in Patent Literature 1 is a technology of detecting properties (concentration and temperature) of measurement target gas by the absorption method using a semiconductor laser.

Gas analysis device and gas analysis method using laser beam


A low temperature alkali metal electrolysis process is provided. The process comprises carrying out the electrolysis in the presence of a co-electrolyte and an alkali metal halide. The co-electrolyte comprises (1) a nitrogen-containing compound and optionally one ore more Group IB halides, Group IIIA halides, Group VIII halides; (2) a Group IIIA halide, a Group VB halide, or combinations of a Group IIIA halide and a Group VB halide; or (3) water. Also provided is a low temperature electrolysis process, which comprises carrying out the process using a cathode that comprises (1) a liquid alkali metal; (2) an alloy of two or more metals selected from the group consisting of bismuth, lead, tin, antimony, indium, gallium, thallium, and cadmium; or (3) an electrically conductive liquid solvated alkali metal. Further provided is an electrolyte comprising an alkali metal halide and a co-electrolyte that comprises (1) a nitrogen-containing compound and optionally one ore more Group IB halides, Group IIIA halides, Group VIII halides or (2) a Group IIIA halide, a Group VB halide, or combinations of a Group IIIA halide and a Group VB halide.

The invention relates to an electrolysis process and electrolytes therefor for producing an alkali metal.
Alkali metals are highly reactive elements and are not found in elemental form in nature. Typical reducing agents, such as hydrogen, are not strong enough to reduce the alkali metals from their compounds to the metallic state. Electrolytic reduction is necessary and was used historically in the classic experiments leading to the discovery of the alkali metals in elemental form in 1807 by Sir Humphry Davy, Assistant to Count Rumford/Thompson at the Royal Institution in London. Electrolytic reduction is used for industrial production of the alkali metals. The currently used process, on a worldwide basis, is the so-called xe2x80x9cDownsxe2x80x9d Process, which was introduced in the early part of the 20th century for the production of sodium and lithium from their chlorides.
The Downs Process uses a molten salt electrolyte consisting of a mixture of NaCl, CaCl2 and BaCl2 in order to reduce the melting temperature of the electrolyte to slightly below 600xc2x0 C. This makes the process more practical compared to using pure NaCl which has a much higher melting point of about 800xc2x0 C. Nevertheless, operating an electrolytic process at such temperature is difficult and presents numerous operating constraints. Because of the high operating temperature of the Down Process, the cell design uses concentrically cylindrical cathodes, wire mesh diaphragms, and anodes rather than the much more space efficient stacked multiple flat electrode and diaphragm element configuration that is normally used in electrochemical engineering practice. Furthermore, the high operating temperature would make a flat wire-mesh steel diaphragm so soft that it would be mechanically unstable and flap back and forth between anode and cathode causing partial shorting/arcing and thereby causing holes to be burned in the diaphragm. Holes in the diaphragm would allow back mixing of sodium produced at the cathode and chlorine produced at the anode, thereby causing low current efficiency of the cell. On the other hand, the concentric cylindrical configuration of the steel diaphragm between the electrodes avoids this difficulty because a wire-mesh cylinder is mechanically much stiffer and mechanically more stable than a flat wire-mesh screen of the same kind.
The above-described concentric cylindrical cell design of the Downs Process, necessitated by the high operating temperature of about 600xc2x0 C., also means that the Downs cell has very poor space efficiency. This translates directly into high capital and operating cost per unit production.
The high operating temperature of the Downs cell in combination with the fact that the molten mixed salt electrolyte has a freezing temperature only about 20xc2x0 C. below the cell operating temperature makes smooth operation of the cells difficult. Cell xe2x80x98freeze-upsxe2x80x99 and other xe2x80x9cupsetsxe2x80x9d are frequent and result in unusually high operating labor requirements for an industrial electrolytic process. This in turn is also the reason why the Downs Process is not amenable to automation. Lithium is currently produced by a modification of the Downs process.
Although there is a low temperature electrolytic process that deposits metallic sodium at the cathode from an NaCl/H2O solution, the sodium metal is not pure sodium but a liquid mercury/sodium amalgam containing a low percentage of sodium, usually about 0.5% Na. The balance of over 99% is mercury metal. This process is used to produce aqueous sodium hydroxide solutions by reacting the dilute sodium amalgam with water. See generally Sodium, Its Manufacture, Properties and Uses, by Marshall Sitting, American Chemical Society Monograph Series, Reinhold Publishing Corp., New York (1956) and Electrochemical Engineering, by C. L. Mantell, McGraw-Hill Book Co., Inc., New York, Toronto, London (1960). This process cannot be used to produce metallic sodium economically because of the problems and the cost of separating mercury from sodium. For example, separation by distillation is impractical because mercury has a much lower boiling point (357xc2x0 C.) than sodium (880xc2x0 C.) and it would be too costly to vaporize 99% mercury to obtain about 1% sodium as the residue.
In recent years fundamental physico-chemical studies have been carried out on electrolytes based on non-aqueous, organic solvents for alkali metal chlorides for battery applications. See J. Electrochem. Soc. Vol. 143, No. 7, pages 2262-2266, July 1996. None of this work resulted in a process for alkali metal production.
Therefore, there is an increasing need to develop an electrolytic process that can be used to produce an alkali metal more economically. There is also a need to develop a process that can improve operability such as, for example, making automation possible.
According to the invention a low temperature electrolysis process is provided, which comprises carrying out the electrolysis in the presence of a co-electrolyte and an alkali metal halide. The co-electrolyte comprises (1) a nitrogen-containing compound and optionally a Group IIIA halide, a Group IB halide, a Group VIII halide, or combinations of two or more thereof; (2) a Group IIIA halide, a Group VB halide, or combinations of a Group IIIA halide and a Group VB halide; or (3) water.
Also according to the invention an electrolysis process is provided, which comprises carrying out the process using a cathode comprising (1) a liquid alkali metal; (2) a liquid low melting alloy of two or more metals selected from the group consisting of bismuth, lead, tin, antimony, indium, gallium, thallium, and cadmium; or (3) a conductive liquid solvated alkali metal.
Further according to the invention an electrolyte is provided. The electrolyte comprises an alkali metal halide and a co-electrolyte that comprises (1) a nitrogen-containing compound and optionally a Group IIIA halide, a Group IB halide, a Group VIII halide, or combinations of two or more thereof, (2) a Group IIIA halide, a Group VB halide, or combinations of a Group IIIA halide and a Group VB halide; or (3) water.

Low temperature alkali metal electrolysis


A voltage regulator may include a comparator with a first comparator input to receive a reference voltage, a second comparator input to receive an output voltage from a phase interleaved converter, and a comparator input. The regulator may also include a set of cascaded flip-flops corresponding to phases of the converter. The set of cascaded flip-flops may have a plurality of phase outputs to trigger a phase transition in the converter if the output voltage falls below the reference voltage.

1. Technical Field
Embodiments generally relate to the regulation of voltage converters. In particular, embodiments relate to single-bound hysteretic regulators for switched-capacitor voltage converters.
2. Discussion
Direct current to direct current (DC-DC) converters such as inductor-based and switched-capacitor converters can be useful in a wide variety of applications. In silicon integrated DC-DC converter applications, however, inductors may present concerns with regard to fabricating magnetic material in a standard complementary metal oxide semiconductor (CMOS) process. Additionally, switched-capacitor converters may require the use of regulation with a dedicated clock or voltage controlled oscillator, which can add to power and area overhead.

Single-bound hysteretic regulation of switched-capacitor converters


In one embodiment, a flight control system is configured to receive one or more pilot inputs intended to effect a particular control outcome for the aircraft, receive one or more current flight parameters of the aircraft, determine whether or not the aircraft is near or in a stall, and if it is determined that the aircraft is near or in a stall, automatically control the aircraft's flight control surfaces in an oscillatory manner that increases the sensitivity of the flight control surfaces and achieves the pilot's intended control outcome.

Airplane stall accounts for about 46% of loss of control events in commercial fixed-wing aircraft. According to the Federal Aviation Association (FAA) "Airplane Flying Handbook," stall is defined to be an aerodynamic condition that occurs when smooth airflow over the airplane's wings is disrupted, resulting in loss of lift. Specifically, a stall occurs when the angle of attack, i.e., the angle between the chord line of the wing and the relative wind, exceeds a critical value. Stall leads to a reduction of the lift force generated by the wings and, hence, loss of altitude, which can lead to a crash if it occurs near the ground. In case of stall, pilots are advised by the FAA to execute a six-step sequence that includes applying nose-down moment to reduce the angle of attack and increasing power to reduce the loss of altitude.
Stall also leads to deterioration in the wing's flight control surface's sensitivity. Specifically, less roll is achieved for particular aileron deflections than the same deflections are used under non-stall conditions. Stall may be accompanied by an undesired rolling motion that may lead to what is called "spin/stall". While the ailerons are typically used in this situation to counteract the undesired rolling motion, the ailerons may not be effective in reversing a stall because of the deterioration in their sensitivity. In fact, the ailerons' effect may even be reversed in post-stall, which creates additional danger in that already critical situation. Moreover, stall usually leads to instabilities in the flight dynamics, which necessitate a feedback stabilizing control system. The design of such a feedback control system based on the conventional aileron input may not be possible near stall because the aileron sensitivity may become reversed and the inflexion point is typically not accurately known and possesses a stochastic nature.

Systems and methods for controlling an aircraft's flight control surface

The Regents of the University of California


A programmable memory cell structure that includes a pair of memory cells is provided. Each pair of memory cells includes a shared control gate and first and second floating gates present about the shared control gate. The first and second floating gates have respective gate regions disposed on respective sides of the control gate. Dielectric structures are present between the control gate and respective ones of the gate regions of the floating gates. The control gate and gates of the first and second floating gates are formed within a single lithographic square.

Field of the Invention
The present invention relates to programmable memory devices such as EEPROMs, nonvolatile memory cells, and flash memory cells. More particularly, the present invention is directed to a twin-cell programmable memory cell structure and to a method of fabricating the same.
Flash memory provides non-volatile memory where blocks of flash memory are erasable in a flash operation. Two well-known types of circuitry that are present in flash memory cells are NAND and NOR. There are a variety of device structures employed for flash memory including two well-known structures, stack gate and split gate. Each of these flash memory structures has it""s own inherent strengths and weaknesses associated therewith. A stack gate device, for example, has its channel region covered by a floating gate that is overlapped by a control gate. In a split gate device, a portion of the channel is controlled directly by the control gate, while the remaining portion of the channel is controlled by the floating gate that is modulated by the control gate.
In a conventional high-density, high-speed NOR flash memory, the random access speed is approximately 30 ns, the write speed is approximately 1-10 Âxcexcs, the write/erase endurance is greater than 106 cycles, the data holding time is greater than 10 years and the cell size is about 0.5 Âxcexcm2. In a commonly employed n-type MOS flash memory device, a gate oxide having a thickness of from about 7 to about 12 nm is employed, and the channel has a length of about 0.25 to about 0.5 nm.
There are a variety of programming methods available for programming the flash memory by writing the desired information to the cells of the flash memory. One of the most widely employed methods used in programming flash memory cells is by channel hot-electron injection. In such programming and during a write cycle, the control gate of the cell being written to is biased to a high voltage level of approximately 7 to 9 V, while the source is maintained at ground and the drain is biased to 3 to 5 V.
Another commonly employed programming method which is well known to those skilled in the art is Fowler Nordheim (FN) tunneling. In FN tunneling, a relatively high control gate voltage of about 13 to 20 V is needed, while both of the drain and source gates are tied to ground. The high voltage needed in FN tunneling for writing to the flash memory cell is required to form an electric field of approximately 12 mV/cm which is needed to facilitate tunneling of electrons from an inversion layer in the channel area into the floating gate. For an erasure operation, a voltage as high as 12 V is applied to the source gate for a source gate erase, while the substrate is grounded and the drain gate is left floating. Alternatively, a negative voltage of about xc3xa2xe2x80x38 to about xc3xa2xe2x80x39 V is applied to the control gate, a positive voltage of about 3 to about 5 V is applied to the drain node and the source node is left floating.
Flash memory provides the advantage of maintaining storage of data even when power is removed and performing block data erasure so that a partial or full memory macro can be reprogrammed again after the original data is completely erased. However, flash memory typically suffers from having a relatively slow programming speed (and write speed). In comparison, the random write access time is approximately 1 ns for a state of the art SRAM and approximately 10 ns for a DRAM. Therefore, flash memory is typically employed for storing data for read operations, but not for true high-speed random read/write applications. Once the stored data needs to be altered a relatively long programming time is required.
Flash memory cells typically require that the threshold voltage (Vt) difference between a programmed cell having a state xe2x80x9c1xe2x80x9d and an un-programmed cell having a state xe2x80x9c0xe2x80x9d be minimally 2 V. This relatively high Vt difference is needed for at least the following reasons: (1) most flash memory designs use a direct sensing technique that requires sufficient Vt difference between a programmed cell or an un-programmed cell for sensing; (2) a high Vt difference helps to prevent degradation which results in shortened life-time for the flash memory due to Vt disturbances caused by read, write and erase operations; and (3) when Vt for a programmed cell is not high enough an array formed by a plurality of flash memory cells is subjected to direct current leakage that is large and would not be tolerable for a low-power operation involving low Vt levels.
The programming speed associated with flash memory is relatively slow since it depends upon an amount of time required to store an amount of charge required on the floating gate to produce a high enough Vt to produce meaningful Vt shift when a cell changes from a state xe2x80x9c0xe2x80x9d to a state xe2x80x9c1xe2x80x9d. Typically, flash memory cells are over programmed in order to ensure a uniform Vt of the programmed cells, further increasing the time required to program a cell and decreasing programming speed.
In addition to the above, there are problems typically associated with the accuracy of flash memory cells. Disturbances, such as unintentional voltage coupling by adjacent cells due to read, write, and erase operations, may cause the Vt programmed cells to deviate from the require Vt, generally causing a read or write failure. Flash memory cells having an inherently small size are oftentimes arranged in cross-point array format.
The sensing scheme used for a cross-point array is usually via an open bitline architecture using a single rail direct sensing or dual rail sensing technique, both of which require a reference voltage generator. An insufficient Vt difference may result in a sense margin too small to be reliable, generally causing read and write failure. Furthermore, a marginal sense signal is susceptible to coupling noise, further compromising the data integrity of the flash memory cell. In general, the reliability of the flash memory is limited due to typical inherent sensing limitations associated with a single polarity.
In view of the aforementioned drawbacks with prior art programmable memory cells such as flash memory cells, there is a continued need for providing new and improved programmable memory cells in which the write speed is enhanced without compromising the reliability and durability of the memory cell.
One object of the present invention is to provide a programmable memory cell structure having an array of memory elements, each element having two cells in which the write speed of the memory cell is enhanced.
A further object of the present invention is to provide a programmable memory cell structure having an array of memory elements, each element having two cells in which the write speed is enhanced without compromising the reliability and durability of the memory cell.
A still further object of the present invention is to provide a programmable memory cell structure having an array of memory cell elements, each element having two cells in which storage capacity of the programmable memory cell is increased.
A yet further object of the present invention is to provide a programmable memory cell structure having a reference line that is common to each of the memory cells.
An even further object of the present invention is to provide a programmable memory cell structure in which the wordline of each memory element is formed borderless to the bitline.
A yet even further object of the present invention is to provide a programmable memory cell structure having a plurality of shallow trench isolation regions that are formed self-aligned to the bitline diffusion regions and the floating gate edges.
Another object of the present invention is to provide a programmable memory cell structure in which the bitlines are borderless to the floating gates and the control line.
It is noted that the term xe2x80x9cprogrammable memory cellxe2x80x9d includes EEPROMs, non-volatile memory cells, flash memory cells and other like memory cells that can be programmed by applying a voltage thereto.
These and other objects and advantages are achieved in the present invention by providing a novel twin-cell programmable memory cell structure in which a sidewall gate formation technique is employed that is capable of forming the inventive twin-cell in the same density as a conventional single cell array. That is, the first cell is formed on one sidewall of the control gate, and the other cell is formed on the other sidewall. The two cells of the inventive memory cell structure are symmetrical and are located relatively close to each other. Moreover, each cell of the twin cell is tied to its own bitline; however, both cells are modulated by the same control gate. One important advantage of the inventive twin-cell programmable memory cell structure is that not only is the cell-density unchanged, but also one cell can be used as a reference cell as the other cell is sensing. One aspect of the present invention relates to a pair of programmable memory cells which comprises a shared control gate, first and second floating gates having respective gate regions disposed on respective sides of the control gate, and dielectric structures disposed between said control gate and respective ones of said gates of said floating gates, wherein said control gate and said gates of said first and second floating gates are located within a space of a single lithographic square.
Another aspect of the present invention relates to a pair of programmable memory cells which comprise a single control gate, a first floating gate, a second floating gate, a first bitline, and a second bitline, wherein said control gate is self-aligned to said first and second floating gates.
A still other aspect of the present invention relates to a programmable memory cell layout for a non-volatile memory cell which comprises a programmable memory wordline borderless to a bitline.
A yet other aspect of the present invention is to provide a method for fabricating the inventive twin-cell programmable memory cell structure. Specifically, the method of the present invention includes the steps of:
forming a pair of programmable memory cells in a slot that is present in a pad layer, said pair of programmable memory cells comprising a shared control gate, first and second floating gates having respective gate regions disposed on respective sides of the control gate, and dielectric structures disposed between said control gate and respective ones of said gates of said floating gates, wherein said control gate and said gates of said first and second floating gates are located within a space of a single lithographic square;
removing said pad layer about said slot;
forming first and second bitlines in regions previously occupied by said pad layer; and
forming a wordline that is borderless to said first bitline and said second bitline, wherein said wordline is interconnected to said shared control gate.

Twin-cell flash memory structure and method

International Business Machines Corporation


A radiation image read-out method and apparatus for a stimulable phosphor sheet, provided with a layer of stimulable phosphor, which has been exposed to radiation to carry information about an image, and the image is thereby stored on the stimulable phosphor sheet. The method includes the steps of: exposing the stimulable phosphor sheet to stimulating rays to emit light in proportion to the amount of energy stored thereon during its exposure to radiation; sensing the emitted light to generate a detection signal; amplifying the detection signal using a first amplifier or a second amplifier, dependent on the magnitude of the detection signal, to generate an amplified detection signal, the first amplifier differing from the second amplifier; and converting the amplified detection signals into a digital signal to form a digital image. In a preferred embodiment, the first and second amplifiers are logarithmic and linear amplifiers.

X-ray imaging technology provides a non-invasive technique for visualizing the internal structure of an object of interest by exposing the object to high energy electromagnetic radiation (i.e., X-rays). X-rays emitted from a radiation source pass through the object and are absorbed at varying levels by the internal structures of the object. As a result, X-ray radiation exiting the object is attenuated according to the various absorption characteristics of the materials which the X-rays encounter.
The absorption characteristics of the object of interest may be captured by placing the object between a high energy electromagnetic radiation source and an image recording medium. As radiation from the source passes through the object, the radiation impinges on the image recording medium with an intensity related to the radiation attenuation caused by the different absorption characteristics of the object. The impinging radiation causes a change in the image recording medium that is proportional to the radiation intensity, thereby storing information about the internal structure of the object. The image recording medium may then be processed to recover the stored information by, for instance, converting it into digital form. Common types of image recording media include sheet film, phosphor media, and the like.
Phosphor plate technology has emerged as a valuable image recording media for computed radiography (CR). When electromagnetic radiation, such as X-ray radiation, impinges on a phosphor plate, the radiation interacts with the phosphor lattice of the plate. The phosphors in the plate store energy proportional to the intensity of the impinging radiation. This energy can later be released by scanning the plate with a laser to excite the phosphors in the plate (i.e., by causing the phosphors to fluoresce). The excited phosphors release radiation that can be detected, quantified and stored as values representing pixels in an image.
As discussed above, radiation penetrating an object being imaged is attenuated according to the various absorption characteristics of the object, e.g., Z-number, density, and the like. In addition, radiation penetrating an object will also undergo a characteristic attenuation due to the thickness of the attenuating material. The thickness of a material refers to a dimension of the material generally in the direction penetrating radiation is propagating. However, this characteristic attenuation is not a linear function of material thickness. Rather, as the thickness of the material increases, the intensity of penetrating rays of radiation will decay exponentially.
FIG. 1 illustrates the exponential relationship between the thickness of intervening material and the attenuation of the penetrating radiation. Object 100 is composed of a material having a uniform density p and a linearly increasing thickness along the z-axis. For example, object 100 may be a piece of aluminum having a ramp shape in the z-direction. Object 100 is illustrated as comprising five layers, each layer adding an incremental thickness z0. Object 100 is exposed to radiation 105 which penetrates object 100 in a direction substantially parallel to the z-axis, as illustrated by exemplary rays 105a-105f. The thickness of the arrows schematically denotes the relative intensity of the radiation of the respective ray.
As shown, exemplary rays 105a-105f enter object 100 at substantially the same intensity (e.g., at the intensity of radiation provided by the radiation source). After the radiation penetrates object 100, it impinges upon phosphor plate 120, which absorbs the radiation and stores energy proportional to the intensity of the impinging rays. As shown by exemplary rays 115a-115f, the increasing thickness of object 100 will attenuate the radiation by increasing amounts. For example, ray 115a undergoes relatively small attenuation as the thickness of object 100 near y=0 is essentially negligible, while ray 115b experiences a relatively large attenuation due to the increased material thickness. As discussed above, this characteristic attenuation does not increase linearly with thickness, but rather the intensity of radiation 105 decreases exponentially with thickness. That is, the change in intensity of radiation 105 between each incremental thickness z0 will start out relatively large (e.g., the large change in intensity between layer 100a and 100b) and will become relatively small to negligible (e.g., the small change in intensity between layers 100d and 100e) as a function of increasing thickness.
The attenuation of radiation through a solid material can be described generally according to the characteristic attenuation function:I=I0e−μ(z)  (1)where I is the intensity of rays having penetrated the material through a thickness z, I0 is the intensity of the radiation emitted from the radiation source before penetrating the material, and μ is the linear absorption coefficient for the material. The linear absorption coefficient μ incorporates various absorption and scattering effects including Thompson scattering, Compton scattering, photoelectric (PE) absorption, pair production, photodisintegration, and the like, and is different for different materials. At radiation power levels typical of diagnostic imaging, the PE absorption is a main contributor to radiation attenuation, and depends, in part, on the density of the material through which the radiation penetrates.
FIG. 2 illustrates a plot 200 including a curve 210 showing the ratio of emitted radiation intensity (I0) to penetrating radiation intensity (I) as a function of thickness z, caused by material having a linear absorption coefficient μ, for example, object 100 in FIG. 1. The ratio ranges from a value of 1 at a thickness of zero (i.e., zero attenuation) and asymptotically approaches zero as a function of increasing thickness (i.e., approaches infinite attenuation).
As a result of the characteristic exponential attenuation, radiation impinging on the phosphor plate will have an exponential bias to material thickness. For relatively small thicknesses, the contrast resolution will be relatively high, while for relatively large thicknesses, the contrast resolution will be relatively small. Stated differently, the change in radiation attenuation will be much more significant for first increments of additional material thickness than for later increments. For example, radiation penetrating object 100 will undergo a greater range of ray attenuation while penetrating layer 100a than it will penetrating 100b. When the radiation penetrates to layer 100f, changes in radiation per incremental thicknesses approaches negligible.
Accordingly, radiation impinging on the phosphor plate will have an exponential distortion as a function of material thickness. When the energy stored in the phosphor plate (i.e., the latent image) is released, the intensity of the released energy may not appropriately reflect the density of the subject matter through which it penetrated, and in turn, the resulting digital image may not be an accurate depiction of the internal structure of the object being imaged, since the contrast resolution will vary across the dynamic range.
Many conventional processing techniques have attempted to compensate for this phenomenon by inverting the effects of the exponential attenuation. For example, rearranging equation (1) and taking the natural logarithm of both sides results in the expression:ln(I/I0)=−μ(z)  (2)which results in a more intuitive linear relationship between attenuation and material thickness z. Accordingly, conventional systems have applied a logarithmic amplifier to detection signals generated during scanning of a phosphor plate to compensate for the characteristic exponential attenuation. The amplified detection signals will appear as if each incremental thickness in material causes the same amount of attenuation on the penetrating radiation, regardless of whether the increment is the first portion of a material or the last portion of the material. That is, logarithmic amplification adjusts values of a detection signal substantially to correspond to a constant change in radiation intensity as a function of material thickness.
FIG. 3 schematically illustrates a scanning process 300 of a conventional computer radiography imaging process. Radiation 305 (e.g., X-ray radiation) is emitted from a radiation source to expose an object being imaged. Radiation 305 may be emitted over some desired area, for example, a region of a patient undergoing a diagnostic procedure. Accordingly, radiation 305 will have an intensity distribution I0(x,y) in the x-y plane and will propagate generally in the z-direction to penetrate the object. As discussed above, the radiation penetrating the object will undergo attenuation that can be generally modeled by the expression in equation (1) as shown in attenuation block 310. Radiation 305′ exiting the object will have an intensity distribution I(x,y) that depends on the absorption characteristics of the object being imaged, and will carry some distortion due to the exponential attenuation characteristic. Radiation 305′ may then impinge on an image recording medium, such as a phosphor plate 320, thus storing the intensity distribution I(x,y) as a latent image in the phosphors of the plate.
The energy stored in phosphor plate 320 may then be released by scanning the phosphor plate with stimulating radiation, for example, a laser beam. The laser beam causes the phosphors in the plate to fluoresce and release stimulated radiation in proportion to the amount of energy stored in the phosphors. Scanning apparatus adapted to release a latent image from an image recording medium are known in the art, for example, the scanning apparatus described in U.S. Pat. No. 6,624,438 (Koren), which is herein incorporated by reference in its entirety. An exposed phosphor plate may be scanned, by means known to those skilled in the art, by providing the laser beam such that it impinges on the phosphor plate in a regular path, traversing the surface of the phosphor plate to release energy stored at various locations along the path in a substantially serial manner.
The phosphor plate then releases energy region by region as the laser traverses in time along the scan path. The energy from each region may ultimately correspond to a pixel in the resulting image. Accordingly, the energy released by the phosphor plate includes radiation having an intensity distribution as a function of time. For example, phosphor plate 320 may release energy by emitting stimulated radiation 315 having an intensity distribution I′(t). Since the scan path is generally planned, the timing of the released energy encodes the location from which the energy was released.
Radiation 315 may be sensed by a detector responsive to stimulated radiation to generate a detection signal indicative of the intensity of the radiation. For example, a photomultiplier tube (e.g., PMT 350 in FIG. 3) may be arranged proximate the phosphor plate such that at least some of radiation 315 emitted from the phosphor plate impinges on the photosensitive surface of PMT 350. In response, PMT 350 generates an electrical signal having a magnitude indicative of the intensity of the impinging radiation. In FIG. 3, PMT 350 generates an electrical signal 325 that varies in magnitude according to the intensity distribution of radiation 315 (e.g., according to I′(t)).
However, the distortion caused by the characteristic exponential attenuation of the object being imaged is propagated through the process and may therefore be carried by electrical signal 325. That is, electrical signal 325 may be a distorted description of the density characteristics of the object being imaged. To compensate, conventional systems have provided electrical signal 325 to logarithmic amplifier 360 to essentially invert the effects of the characteristic exponential attenuation. Logarithmically amplified signal 325′ may then be provided to an analog-to-digital converter (ADC) 370 to convert the electrical signal into a digital signal 335 to form a digital image 390. The resulting image may then be transmitted, further processed and/or displayed such that the internal structures of the object may be viewed.
Issues associated with image read-out are described in U.S. Pat. No. 5,357,118 (Fukuoka), U.S. Pat. No. 5,278,754 (Arakawa), and U.S. Pat. No. 5,535,289 (Ito), all incorporated herein by reference.

Method and apparatus for improved contrast resolution


The brake system having an electrically controllable brake apparatus of a trailer, the brake apparatus includes a control unit which is connected via electrical lines to an electrical energy source of a tractor. In braking, electrical currents are brought about of such a magnitude as to cause severe voltage drops in long lines that the functional safety of the brake apparatus may be threatened. The brake apparatus therefore has an electrical energy storage device disposed on the trailer, which can be charged by an energy source of the tractor and can be discharged upon triggering of the brake apparatus of the trailer. Voltage drops in the relatively short lines between the energy storage device and the control unit are therefore minimum. The lines between the electrical energy source of the tractor and the energy storage device of the trailer are charged by only low charging currents. The voltage drop is therefore low despite the long line length.

The invention is based on a brake system for vehicle combinations such as truck-trailers or tractor-trailers, as defined hereinafter. A brake system is already known (German Offenlegungsschrift 37 03 639) in which the electrical energy is supplied to the brake apparatus located in the trailer by the tractor. Because of the great length of the vehicle combination, the supply lines are quite long. When the brake apparatus comes into operation, relatively high currents flow in the lines between the tractor and the trailer. The line resistance causes a drop in voltage, which may impair safe operation of the brake apparatus, especially in the case of an anti-skid (ABS) and/or traction control system.


The disclosure relates to a headband for a headset, the headband comprising a first strip and a second strip detachably assembled together. The first strip comprises at least one through opening and the second strip is detachably connected via the through opening to the first strip as a cover. The second strip comprises first and second parts at least partly covering the first strip. The disclosure further relates to a headset comprising a headband and a method for assembly of a headband for a headset.

EP 2 566 191 A2 and US 2016/0277828 A1 disclose headphones/-sets allowing a wearer to personalize the headphones/-sets by inserting a variety of interchangeable décor strips onto a headband of the headphones/-sets.
A problem with the solutions of the prior art is that the headbands are made up of many different interconnected parts making any interchange of the headbands and their appearance complicated. There is thus a need for improved changeability of headbands for headsets.

Headband for a headset and a method for assembly of a headband for a headset


Equipment on automotive vehicle is controlled by a system including at least one semiconductor light sensor having variable sensitivity to light. Each light sensor generates a light signal indicative of the intensity of light incident on the light sensor. Control logic varies the sensitivity of the light sensor and generates equipment control signals based on received light signals. Sensitivity of light sensors may be varied by changing the integration time for producing charge from light incident on light transducers, by selecting between light transducers of different sensitivity within the light sensor, by using a light transducer with a sensitivity that is a function of the amount of incident light, and the like. Controlled equipment includes devices such as automatically dimming rearview mirrors, headlamps, and moisture removal means.

The present invention relates to automatically controlled automotive vehicle equipment of the type using light sensors to monitor light levels.
The continuing reduction in the size and cost of electronic circuits, in particular microprocessors, makes possible the inclusion of an increasing amount of intelligence for the automatic control of automotive vehicle equipment. Examples include: rearview mirrors that adjust their reflectivity in response to the levels of ambient light and glare from other vehicles; moisture on windows sensed and removed by automatic wipers, defrosters, defoggers, and the like; windows that automatically close when rain is detected; headlamps switched in response to ambient light levels; and heating and cooling of the vehicle passenger compartment automatically adjusted in anticipation of changes in external conditions.
Systems that automatically control automotive equipment can advantageously employ one or more sensors for measuring light levels. Automatically dimmable rearview mirrors, and in particular electrochromic mirrors, using light sensors, are described in U.S. Pat. No. 4,902,108 to Byker; U.S. Pat. No. 5,724,187 to Varaprasad et al.; U.S. Pat. No. 5,928,572 to Tonar et al.; and U.S. Pat. No. 6,020,987 to Baumann et al. In the case of mirrors having automatic reflectivity control, such as electrochromic mirrors, it is advantageous to use sensors to detect both forward and rear light levels. Among the dual sensor designs proposed include those described in U.S. Pat. No. 3,601,614 to Platzer; U.S. Pat. No. 3,746,430 to Brean et al.; U.S. Pat. No. 4,580,875 to Bechtel et al.; U.S. Pat. No. 4,793,690 to Gahan et al.; U.S. Pat. No. 4,886,960 to Molyneux et al.; U.S. Pat. No. 4,917,477 to Bechtel et al.; U.S. Pat. No. 5,204,778 to Bechtel; U.S. Pat. No. 5,451,822 to Bechtel et al.; and U.S. Pat. No. 5,715,093 to Schierbeek et al. A vision system is disclosed in U.S. patent application Ser. No. 09/001,855, entitled xe2x80x9cVEHICLE VISION SYSTEM,xe2x80x9d filed by Jon H. Bechtel et al. on Dec. 31, 1997, the disclosure of which is incorporated herein by reference thereto.
Various moisture detectors are also known that employ a light sensor. Examples of such detectors include those described in U.S. Pat. No. 5,821,863 to Schrxc3x6der et al.; U.S. Pat. No. 5,796,106 to Noack; U.S. Pat. No. 5,661,303 to Teder; U.S. Pat. No. 5,386,111 to Zimmerman; U.S. Pat. No. 4,973,844 to O""Farrell et al.; U.S. Pat. No. 4,960,996 to Hochstein; U.S. Pat. No. 4,930,742 to Schofield et al.; U.S. Pat. No. 4,871,917 to O""Farrell et al.; U.S. Pat. No. 4,867,561 to Fujii et al.; U.S. Pat. No. 4,798,956 to Hochstein; U.S. Pat. No. 4,652,745 to Zanardelli; and RE No. 35,762 to Zimmerman. A moisture detection system is disclosed in U.S. Pat. No. 5,923,027, entitled xe2x80x9cMOISTURE SENSOR AND WINDSHIELD FOG DETECTOR USING AN IMAGE SENSOR,xe2x80x9d issued on Jul. 13, 1999, to Joseph S. Stam et al., the disclosure of which is incorporated herein by reference thereto.
A variety of systems for controlling headlamps using a light sensor are also known, including those described in U.S. Pat. No. 4,891,559 to Matsumoto et al.; U.S. Pat. No. 5,036,437 to Macks; U.S. Pat. No. 5,235,178 to Hegyi; U.S. Pat. No. 5,537,003 to Bechtel et al.; U.S. Pat. No. 5,416,318 to Hegyi; U.S. Pat. No. 5,426,294 to Kobayashi et al.; U.S. Pat. No. 5,666,028 to Bechtel et al., and U.S. Pat. No. 5,942,853 to Piscart. Such systems employ a light sensor to detect conditions under which the headlamp light intensity is altered. Other systems are disclosed in U.S. Pat. No 5,837,994, entitled xe2x80x9cCONTROL SYSTEM TO AUTOMATICALLY DIM VEHICLE HEAD LAMPS,xe2x80x9d issued Nov. 17, 1998, to Joseph S. Stam et al.; U.S. Pat. No. 5,990,469, entitled xe2x80x9cCONTROL CIRCUIT FOR IMAGE ARRAY SENSORS,xe2x80x9d issued to Jon H. Bechtel et al. on Nov. 23, 1999, and U.S. Pat. No. 5,998,929, entitled xe2x80x9cCONTROL SYSTEM FOR AUTOMOTIVE VEHICLE HEADLAMPS AND OTHER VEHICLE EQUIPMENT,xe2x80x9d issued on Dec. 7, 1999, to Jon H. Bechtel et al., the disclosures of which are incorporated herein by reference thereto.
Such automatically controlled equipment may employ one or more cadmium sulfide (CdS) cell as a light sensor. CdS cells are photosensitive resistors exhibiting increasing conductance with increasing light levels. CdS cells offer some advantages, such as being relatively low in cost, demonstrating good sensitivity to low light levels, and providing a spectral response somewhat similar to that of the human eye. However, equipment employing such cells can not fully realize these advantages due to other characteristics of CdS cells, such as: a high degree of variance between cells, slow response at low light levels, poor environmental stability, limited dynamic range, and difficulty being assembled in automated electronic manufacturing processes and equipment. Rearview mirrors employing CdS cells for sensing ambient light and glare may incorporate the CdS cell into a full or partial bridge to increase the dynamic range of the cell. However, the bridge output will only represent a fixed relationship between an ambient light level and a glare level, which fixed relationship is often not appropriate throughout the range of ambient light levels monitored.
Vehicle equipment, such as automatic dimming mirrors, has also used one or more discrete photodiodes configured as a light-dependent current source. Relative to equipment using CdS cells, equipment using photodiodes will experience less operational variance due to the light sensor part performance, will demonstrate better environmental stability, and will be more easily adapted to automated manufacturing. However, photodiodes themselves are relatively expensive and produce very low currents at low light levels. These low currents require the inclusion of special amplification techniques to achieve a useful signal for the electronic components, increasing the cost and complexity of the equipment.
Another approach to providing equipment responsive to ambient light is described in U.S. Pat. No. 5,760,962 issued to Schofield et al. wherein an automatically dimmable mirror is disclosed that incorporates a large imaging array to gather light from behind and beside the vehicle. Each light transducer, or pixel, within the array views a separate area within the target spatial distribution of the light sensor. The equipment measures ambient light by examining pixels generally directed sideways. The cost of the imaging array, the required lens, and the complicated signal processing logic make equipment using the imaging array prohibitively expensive for many automotive applications. An additional problem is that light collected from a side view less accurately represents the ambient light experienced by the vehicle operator than does light from a forward view.
One difficulty with providing equipment employing light sensors is the occurrence of operating anomalies when the equipment is subject to high temperatures. Some equipment employs light sensors that are extremely non-linear at high temperatures. Other equipment may suffer a permanent change in operating characteristics after being exposed to high temperatures. Such a permanent change can occur in equipment using a CdS cell exposed to prolonged sun on a hot day, such as prolonged exposure to temperatures in excess of 87xc2x0 C. Sensors may even provide completely false readings, such as by identifying a bright light condition in low light conditions, due to excessive thermal noise. Traditionally, the only way to deal with this problem has been to incorporate a temperature sensor and additional electronics into the vehicle equipment to compensate for sensor performance changes resulting from temperature variations. Such electronics add cost and complexity to the equipment.
It can thus be seen that a difficulty with implementing automatically controlled equipment is accommodating the light sensor. Inclusion of light sensors typically introduces complex and costly manufacturing processes. However, the equipment needs to be inexpensive to fall within the range deemed acceptable by an automobile purchaser. Additionally, manufacturers of vehicles incorporating such equipment must either accept inconsistent operating performance or use complex and costly circuitry and processes to accommodate these variations. Such additional provisions may be required to enable the equipment to operate with sufficiently consistent sensitivity across a wide dynamic range as is required for operation in the ranges of temperature, humidity, shock, and vibration experienced within a vehicle.
What is needed is more cost-effective equipment using light sensors operable over a wide range of light conditions and temperatures.
Automotive vehicle equipment is controlled by a system including at least one semiconductor light sensor having variable sensitivity to light. A light sensor generates a light signal indicative of the intensity of light incident on the light sensor. Control logic varies the sensitivity of light sensors and generates equipment control signals based on received light signals. Sensitivity of light sensors may be varied by changing the integration time of charge produced by light incident on light transducers, by selecting between light transducers of different sensitivity within the light sensor, by using a light transducer with a sensitivity that is a function of the amount of incident light, and the like.
In one embodiment, the system for automatically controlling vehicle equipment includes at least one semiconductor light sensor outputting a discrete light signal based on light incident over a variable integration period. Control logic generates at least one equipment control signal based on the discrete light signal.
In another embodiment, the vehicle equipment includes a rearview mirror having a dimming element with a variably reflective surface, the degree of reflectivity based on the equipment control signal. The light sensors include at least one of an ambient light sensor positioned to receive light generally in front of the vehicle and a glare sensor positioned to view a scene generally behind a vehicle operator.
In still another embodiment, the vehicle equipment includes at least one headlamp. The light sensors include at least one ambient light sensor positioned to receive light generally in front of and above the vehicle. The light sensors may be a first ambient light sensor admitting light in a first band of frequencies and a second ambient light sensor admitting light in a second band of frequencies different from the first band of frequencies. The control logic can determine a first filtered ambient light level from the light signal output from the first ambient light sensor and a second filtered ambient light level from the light signal output from the second ambient light sensor. A threshold based on the first filtered ambient light level and the second filtered ambient light level is found. A headlamp control signal based on the threshold and at least one of the first filtered ambient light levels and the second ambient light level is generated.
In yet another embodiment, the control of vehicle equipment is based on detecting the presence of moisture on a window. The system includes an emitter for emitting light at the window. At least one light sensor is positioned to receive light from the emitter reflected from the window. The control logic receives a first light signal from the light sensor with the emitter turned off. The emitter is turned on and a second light signal is received from the light sensor. The presence of moisture is determined based on the first light signal and the second light signal.
A method for automatically controlling equipment in an automotive vehicle is also disclosed. Sensitivity is determined for at least one semiconductor light sensor. Charge incident on the light sensor is integrated to achieve the determined sensitivity. A discrete light signal is generated based on the light incident on the light sensor over the integration period. The discrete light signal can be analog or digital. In one embodiment, the discrete signal has a digital level with a variable, analog length. At least one vehicle equipment control signal is then generated based on the discrete light signal.

Vehicle equipment control with semiconductor light sensors


A vertical axis wind turbine includes a support axis and a wind wheel. The wind wheel includes a rotation base, plural rotation stand sets, plural deflection structures, plural blades, and plural deflection-limiting structures corresponding to the plural blades. The rotation base is rotatably disposed on the support axis. The plural rotation stand sets may define a rotation plane. A first end of each rotation stand set is fixedly disposed on the rotation base. Each blade is pivotally coupled to a second end of the corresponding rotation stand set through the corresponding deflection structure. Consequently, an angle of attack of the blade in an airflow is correspondingly adjusted. When one of the plural blades is deflected, the corresponding deflection-limiting structure generates a first rotational torque in a first rotating direction or a second rotational torque in a second rotating direction so as to rotate the rotation base.

With increasing environmental consciousness, there are growing demands on clean energy, natural energy or renewable energy. For example, solar energy, wind power, water power, marine energy and tide energy are the well-known power sources of the clean energy, natural energy or renewable energy. As known, wind power is generated by using airflow (e.g. wind) to driving rotation of a wind wheel of a wind turbine and using a primary generator of the wind turbine to convert the rotating kinetic energy into electric power. Generally, the wind wheel comprises plural blades or airfoils.
Generally, the wind turbines are classified into two types, i.e. a horizontal axis wind turbine and a vertical axis wind turbine. During operations of the horizontal axis wind turbine, the central axis of the wind wheel is in parallel with the ground or the direction of the airflow. During operations of the vertical axis wind turbine, the central axis of the wind wheel is perpendicular to the ground or the direction of the airflow. As the direction of the airflow changes, for allowing the wind wheel to be rotated with the airflow, the orientation of the wind wheel of the horizontal axis wind turbine should be correspondingly changed. However, in response to the airflow in any direction, the wind wheel of the vertical axis wind turbine can be rotated. That is, even if the direction of the airflow changes, it is not necessary to adjust the orientation of the central axis of the wind wheel.
FIG. 1 is a schematic perspective view illustrating a conventional vertical axis wind turbine. As shown in FIG. 1, the vertical axis wind turbine 100 principally comprises a support axis 11, a primary generator 12, plural fixing props 13, and plural blades 14 corresponding to the fixing props 13. For clarification, three blades 14 are shown in the drawing. The plural blades 14 are fixedly disposed on the corresponding fixing props 13. Consequently, the blades 14 and the fixing props 13 are collaboratively constituted as a wind wheel. The wind wheel is rotatably disposed on the support axis 11. Upon rotation of the wind wheel, the support axis 11 is used as a central axis. Moreover, the support axis 11 is used for supporting the primary generator 12. The primary generator 12 may be disposed within the support axis 11, or located over or under the support axis 11. Consequently, the support axis 11 (i.e. the central axis of the wind wheel) is perpendicular to the ground or the direction of the airflow. As shown in FIG. 1, the direction of the airflow is denoted by the direction of an ambient wind speed v. Moreover, upon rotation of the wind wheel, the primary generator 12 is driven to generate electric power.
Generally, as shown in FIG. 1, the cross section of the blade 14 of the vertical axis wind turbine 100 has an airfoil configuration. According to the aerodynamic principle, the airflow around the airfoil may create a lift force. In response to lift force, a rotational torque is generated to rotate the wind wheel. Moreover, for achieving the both functions of generating a large rotational torque and supporting the weight of the blade 14 during operation of the wind wheel, the connecting point (i.e. the fulcrum P1) between the fixing prop 13 and the corresponding blade 14 is separated from a leading edge of the blade 14 by a specified distance. For example, the fulcrum P1 is separated from the leading edge of the blade 14 by one third or one fourth of a chord length.
The wind turbine 100 as shown in FIG. 1 is a wind turbine with vertical type (H-type) blades. It is noted that the shapes of the blades of the vertical axis wind turbine are not restricted. For example, the blades of other vertical axis wind turbines may have symmetric shapes, arc shapes, curvy shapes, helical shapes or other special shapes.
FIGS. 2A and 2B schematically illustrate two-dimensional expression of associated forces exerted on the blade of the vertical axis wind turbine of FIG. 1. As shown in FIG. 2A, a relative wind speed w is a wind speed relative to the blade 14 in the ambient wind speed v. An angle between the relative wind speed w and a chord line c of the blade 14 (i.e. the line passing through the leading edge and the trailing edge of the blade) is referred as an angle of attack (α).
According to aerodynamics, the magnitude of the angle of attack (α) is related to the magnitude of the lift force that is caused by the airflow and exerted on the blade 14. In case that the direction and speed of the ambient wind speed v is constant and the blade 14 is fixedly disposed on the corresponding prop 13, the direction of relative wind speed w on the blade 14 is unceasingly changed as the blade 14 is rotated. Consequently, during rotation of the blade 14, the magnitude of the angle of attack (α) is correspondingly changed. That is, as the blade 14 is rotated one turn, the azimuth angle varies from 0 to 360 degrees, and the lift forces corresponding to different angles of attack (α) are different. Consequently, the rotational torques for rotating the blade 14 about the vertical axis and corresponding to different azimuth angles will be different. In other words, it is impossible to control and maintain the optimal angle of attack to acquire the optimal lift force. For example, if the angle of attack is too large, the drag coefficient of the oncoming airflow will increase and lift coefficient of the oncoming airflow will decrease.
Moreover, the blade 14 is fixedly disposed on the corresponding prop 13, and the fulcrum P1 between the fixing prop 13 and the corresponding blade 14 is not located at the leading edge of the blade 14. Upon rotation of the tip of the fixing prop 13, the fulcrum P1 between the fixing prop 13 and the corresponding blade 14 is moved along a circular path (i.e. in a circular motion). That is, during the practical rotation, the leading edge of the blade 14 is not rotated along the tangential direction of the circular trajectory of the fulcrum P1. In particular, the leading edge of the blade 14 is rotated at a pitch angle γ (also referred as an angle of pitch).
As shown in FIG. 2A, the pitch angle γ is the angle between the moving direction m of the blade 14 (especially the leading edge of the blade 14) and the chord line c of the blade 14. The direction of the chord line c is in parallel with the tangential direction of the circular trajectory of the fulcrum P1. Under this circumstance, the magnitude of the lift force generated by the airflow around the blade 14 is dependent on the angle of attack (α). In addition, the positive or negative effect caused by the magnitude of the pitch angle γ may directly influence the change of the angle of attack (α) during rotation. On the other hand, if the fulcrum P1 between the fixing prop 13 and the corresponding blade 14 is changed, the pitch angle γ is correspondingly changed, and the angle of attack (α) is correspondingly influenced. Since the generated rotational torque is different, the rotating efficiency is different.
Moreover, as shown in FIG. 2B, the ambient wind speed v is the prevailing wind speed (i.e. in the direction of the airflow) in the ambient wind field. In FIG. 2B, the forces exerted on the blade 14 at the positions corresponding to two azimuth angles are shown. Generally, the azimuth angles from 0 to 180 degrees correspond to a windward side, and the azimuth angles from 180 to 360 degrees correspond to a leeward side. At the azimuth angle of 90 degrees, a lift force L1 caused by the relative wind speed w is exerted on the blade 14. The lift force L1 is perpendicular to the relative wind speed w. The lift force L1 may be resolved into two components. One component L1n is projected along the normal direction of the rotation plane, and the other component L1t is projected along the tangential direction of the rotation plane. Similarly, at the azimuth angle of 270 degrees, a lift force L2 caused by the relative wind speed w is exerted on the blade 14. The lift force L2 may be resolved into two components L2n and L2t. For clarification and brevity, the drag force (in parallel with the relative wind speed w) caused by the airflow and exerted on the blade 14 is not shown.
From the above discussions, each of the components L1t and L2t may exert a thrust force on the blade 14, thereby generating a rotational torque of rotating the blade 14. The component L1n at the windward side may exert a pressure on the support axis 11 (i.e. the central axis). The component L2n at the leeward side may exert a tension on the support axis 11. Since the direction of the pressure (i.e. the normal direction of the blade 14 toward the support axis 11) and the direction of the tension (i.e. the normal direction of the blade 14 away from the support axis 11) are the same as the direction of the ambient wind speed v (i.e. the direction of the airflow), the support axis 11 is pushed and pulled by the pressure and the tension, respectively. In other words, the support axis 11 is readily damaged.


A dual range infinitely variable transmission utilizes a continuously variable speed mechanism in conjunction with a fixed ratio speed mechanism to provide two power paths from the input to the rotatable output. A jaw clutch is utilized to switch between the high range and low range of the transmission. A reaction type clutch is utilized to provide a positive neutral for the transmission.

1. Field of the Invention
The present invention relates to a dual range infinitely variable transmission and, more particularly, to an infinitely variable transmission which includes two power paths to a pair of planetary gearsets. The transmission utilizes a continuously variable speed mechanism in conjunction with a fixed ratio speed mechanism for the two power paths. A two-position jaw clutch means is utilized to switch between the single path high range and the dual path low range of the transmission. A reaction type clutch is utilized to lock the sun gear of the second planetary gear set to provide a positive neutral.
2. Description of the Prior Art
The typical automotive transmission is shifted in specific, discrete steps between a high-torque, low-speed mode for vehicle launch and a high-speed, low-torque mode for vehicle operation at highway speeds. In a manual transmission, shifting is accomplished by the engagement of gear sets. In an automatic transmission, shifting is accomplished by the controlled engagement of friction elements. As a result of the limitations of shifting in discrete steps, the most efficient vehicle operation can only be approximated. Automotive engineers have long recognized that efficiency would be improved if the transmission could be adjusted continuously between ratios in order to compensate for changing conditions. Such continuous adjustment would allow engine operation to approach maximum efficiency for any particular condition.
Continuously variable transmissions, or CVT's, are directed to such increases in efficiency. The typical CVT employs a continuously variable speed mechanism in the form of a variable pulley with a pair of flanges mounted on an input shaft such that at least one of the flanges is movable axially with respect to the other. A similar variable pulley is mounted on an output shaft. A flexible belt couples the pulleys to allow the transfer of torque between the shafts when one of the shafts is driven. When the pitch radius of one pulley is changed, the pitch radius of the other pulley is changed simultaneously in the opposite direction. As a result, the drive ratio between the input and output shafts is varied in a continuous, smooth manner within the ratio range of the speed mechanism.
Heretofore, efforts have been made to extend the range of the transmission drive ratio of the CVT beyond the ratio range of the variable speed mechanism, that is, to devise an infinitely variable transmission. One such effort utilized two power paths between the torque input source and the rotating output. One power path comprised the conventional variable speed mechanism described above with variable pulleys on the input and output shafts and a belt connecting the pulleys. The second power path comprised a pair of sprockets, one located on each of the input and output shafts, and a silent chain drivingly connecting the two sprockets. The silent chain drive provided a fixed ratio drive.
In this prior art infinitely variable transmission, a sun portion of a planetary gear mechanism was driven by the output shaft of the variable speed mechanism. A planetary carrier portion of the same planetary gear mechanism was driven by the output sprocket of the fixed ratio chain drive. The transmission output speed in the dual drive mode was increased by changing the belt ratio to decrease the sun gear speed. The direct drive mode utilized only the variable speed mechanism as the fixed ratio chain drive became free wheeling.
An inherent weakness in such a prior art transmission which used more than a single clutch is that, during shifting, both clutches may be simultaneously engaged or simultaneously disengaged. A potentially dangerous situation is encountered during such simultaneous engagement or disengagement.
There has therefore been a need for an infinitely variable transmission with dual power paths which utilizes a clutch mechanism to actuate the dual drive and the direct drive. Moreover, there is a need for an infinitely variable transmission which reduces the number of components utilized in the gear reduction system and yet provides the necessary gear reduction for the output. There is also a need for a control system for such an infinitely variable transmission which allows precise control of the shifting between power paths and the componentry.
The infinitely variable transmission of the present invention provides such a structure and control system.

Dual range infinitely variable transmission


An optical pick-up includes light sources for emitting light beams having different wavelength, the light sources being switched according to the kind of optical discs, a refractive lens element for converging the light beams from the light sources onto recording layer of the optical disc; and a spherical aberration correcting element on which a concentric phase grating structure is formed, the phase grating structure altering spherical aberration in response to change of wavelength to correct change of the spherical aberration due to change of the thickness of the cover layer. The spherical aberration correcting element has a wavelength dependence such that spherical aberration varies in the undercorrected direction as wavelength of incident light increases.

The present invention relates to an optical pick-up of an optical disc apparatus that is able to record/reproduce data of a plurality of kinds of optical discs whose cover layers have different thickness. Particularly, the present invention relates to the optical pick-up that has a combination of a refractive lens element and a diffractive element.
The optical disc includes an information layer on which digital information is recorded, and a transparent cover layer that covers the information layer. A laser beam from the optical pick-up forms a beam spot on the information layer through the cover layer. The distance between the optical pick-up and the information layer varies depending upon the thickness of the cover layer.
Namely, the thicker the cover layer is, the farther the distance to the beam spot from the optical pick-up is. For example, since the cover layer of a compact disc (CD) or that of a CD-R has the thickness of 1.2 mm, and the thickness of the cover layer of a digital versatile disc (DVD) is 0.6 mm, the optical pick-up is required to move the beam spot away from the optical pick-up by 0.6 mm in the cover layer (0.4 mm in air) when the DVD is replaced with the CD or the CD-R.
Although a paraxial beam spot moves as the objective lens is moved, the change of the thickness of the cover layer changes spherical aberration. If the optical pick-up only moves the objective lens when the disc is replaced, wave front aberration of the laser beam is deteriorated. Thus, the diameter of the beam spot is increased, which prevents the optical disc apparatus from reproducing the recorded information from the CD. For instance, when the objective lens, which is designed to minimize the spherical aberration when the recorded information is reproduced from the DVD, is used for reproducing the information from the CD, the spherical aberration becomes too large to reproducing the information even if the objective lens moves to bring the beam spot to be coincident with the information layer.
Therefore, there is known as prior art, an optical pick-up that adjusts the condition of the laser beam entering into the objective lens according to the thickness of the cover layer.
For example, Japanese Provisional Patent Publication No. HEI 7-98431 discloses such an optical pick-up. The optical system shown in this publication employs a holographic lens on the laser source side of the objective lens to divide the laser beam from the laser source into a zero order parallel diffractive beam and a first order divergent diffractive beam. The zero order diffractive beam is used for the optical disc having a thinner cover layer (i.e., the DVD)) the first order diffractive beam is used for the optical disc having a thicker cover layer (i.e., the CD and CD-R). The optical pick-up of the publication enables to form the diffraction-limited beam spots for the respective optical discs when the holographic lens is designed to obtain the most suitable laser beams according to the thickness of the cover layers.
However, since the optical pick-up of the publication always divides the laser beam from the laser source into the zero and first order diffractive beams, and only one of these beams is used for recording/reproducing information at a time, the maximum efficiency in use of the light quantity is not more than 40%.
Further, when one of the diffractive beams is being used for recording/reproducing the information, the other diffractive beam is an unnecessary beam, which increases noise.
Still further, the recording density of the DVD is higher than that of the CD, which requires the optical pick-up for the DVD to form a smaller beam spot than the optical pick-up designed for the exclusive use of the CD (hereinafter referred as an exclusive CD pick-up). Since the diameter of the beam spot has a positive correlation with the wavelength of the laser beam, the optical pick-up for the DVD requires the laser source whose oscillation wavelength is 635 through 660 nm that is shorter than the oscillation wavelength of the exclusive CD pick-up (i.e. 780 through 830 nm). On the other hand, the reflection characteristics of the CD-R requires the laser source whose oscillation wavelength is about 780 nm.
Accordingly, when the optical pick-up having a single laser source as described in the publication employs a laser source that emits a laser beam having a shorter oscillation wavelength, it cannot reproduce the information from the CD-R.
It is therefore an object of the present invention to provide an objective lens for an optical pick-up, which is capable of recording/reproducing information on a plurality of kinds of the optical discs (e.g., CD, CD-R and DVD) whose cover layers are different in the thickness. Further, the present invention is aimed to provide a composite objective lens that has higher efficiency in use of the light quantity than the conventional optical pick-up as disclosed in the above-identified publication.
For the above object, according to the present invention, there is provided an improved optical pick-up, which includes:
a plurality of light sources for emitting light beams having different wavelength, the light sources being switched with each other according to the kind of optical disc, used;
a refractive lens element for converging the light beams from the light sources onto a recording layer of the optical disc; and
a spherical aberration correcting element on which a concentric phase grating structure is formed, the phase grating structure altering spherical aberration in response to change of wavelength to correct change of the spherical aberration due to change of the thickness of the cover layer.
With this construction, since the spherical aberration correcting element changes spherical aberration corresponding to a change of the wavelength of the laser beam, the switch of the laser sources can compensate a change of spherical aberration due to the change of the cover layer""s thickness.
The spherical aberration correcting element preferably has no paraxial power, and diffracts the light beams in the same diffractive order, for example, in a first diffractive order.
Further, the light source having shorter emitting wavelength may be used for the optical disc having a thinner cover layer that has higher recording density, and the light source having a longer emitting wavelength may be used for the optical disc having a thicker cover layer that has lower recording density. In such a case, the peripheral area of the spherical aberration correcting element is preferably optimized for the optical disc having the thinner cover layer with the shorter wavelength. The peripheral area is the outside of an effective diameter corresponding to numerical aperture required for the optical disc having the thicker cover layer. In other definition, the peripheral area is the outside of a 85% line of an effective diameter of the spherical aberration correcting element. The peripheral area may be formed as a continuous surface or a grating surface. In the later case, a blazed wavelength of the peripheral area should be shorter than that of the central area.
The spherical aberration correcting element maybe located between the light sources and the refractive lens element. The refractive lens element and the spherical aberration correcting element constitute a composite objective lens. The composite objective lens may be designed for an infinite system in which parallel light beams are incident on the lens or a finite system in which divergent light beams are incident on the lens. In the infinite system, a collimator lens is required between the light sources and the composite objective lens.
Further, the spherical aberration correcting element preferably has a wavelength dependence such that spherical aberration varies in the undercorrected direction as wavelength of incident light increases.
As described above, the spherical aberration varies in the overcorrected direction as the thickness of the cover layer increases. Therefore, when a longer wavelength laser source is used for an optical disc having a thicker cover layer, and a shorter wavelength laser source is used for an optical disc having a thinner cover layer, the change of the spherical aberration due to change of the cover layer""s thickness is corrected by the above-mentioned wavelength dependence of the spherical aberration correcting element.
An additional optical path length added by the phase grating structure is expressed by the following optical path difference function "PHgr"(h):
"PHgr"(h)=(P2h2+P4h4+P6h6+ . . . )xc3x97xcex
where P2, P4 and P6 are diffractive coefficients of second, fourth and sixth orders, h is a height from the optical axis and xcex is wavelength of incident light.
The phase grating structure of the spherical aberration correcting element may satisfy the following condition (1);
xe2x88x9215 less than "PHgr"(h45)/xcexxe2x88x92P2xc3x97(h45)2 less than xe2x88x927xe2x80x83xe2x80x83(1)
where h45 is the height from the optical axis of a point where a light ray whose NA is 0.45 intersects the phase grating structure.
Preferably, one surface of the spherical aberration correcting element is a continuous surface and the other surface thereof is the grating surface. A base curve of the grating surface may be a flat plane or a rotationally symmetrical aspherical surface. The base curve is defined as a shape of the surface that does not include the phase grating structure.