A high-efficiency low-cost electronic controller circuit for powering incandescent lamps which provides constant RMS voltage output from a battery or other varying output DC supply. The controller prolongs lamp life by limiting the cold filament in-rush power thereby reducing filament thermal shock deterioration. The controller further prolongs lamp life by supplying rectified AC power which reduces lamp filament embrittlement. A supply voltage monitor indicates a low-battery condition by flashing the lamp. A battery tester enables determination of the battery voltage which is indicated by pulse-coded modulation of the incandescent lamp brightness. A transistor contained in the controller eliminates the usual high-current mechanical power switch.

1. Field of Invention
This invention relates to more efficient production of light from battery-powered flashlights by the addition of a voltage regulator circuit which supplies the incandescent lamp with relatively constant RMS voltage independent of battery voltage output. During start-up the regulator circuit in the present invention provides gradual power application to the incandescent lamp life reducing cold-filament thermal shock and thereby extending lamp life. Lamp life is further extended by the use of rectified AC power which reduces filament embrittlement. A voltage monitor circuit signals the approach of battery end-of-life by modulating the light output of the flashlight. A battery tester enables determination of the battery voltage which is indicated to the user by the flashing pattern of the light. An inherent power-off characteristic of the present invention eliminates the need for the commonly used high power on-off switch.
While this invention is intended primarily for the improvement of flashlight performance, it can also be used to advantage in other illumination products or other product applications where accurate delivery of root mean square, RMS, power to a resistive load is required.
2. Flashlights
Currently commercialized flashlights employ a direct mechanically switched connection between the battery power source and the incandescent lamp. This simple design approach provides a very low initial-cost solution which suffers from several shortcomings. All batteries of the type traditionally used in current flashlights exhibit relatively poor voltage maintenance characteristics over their useful life which results in substantial variability of light output and less that optimum energy conversion efficiency. Additionally, the current flashlight design approach is also subject to premature lamp and switch failures caused by very high cold-filament in-rush currents which exceed steady-state current levels by as much as a factor of ten.
Incandescent lamps produce visible light by resistive heating of the lamp filament to elevated temperatures in the range of 2200.degree. K to 3350.degree. K..sup.1 Most of the electrical power applied to the incandescent lamps is lost to thermal convection and emission in the infra-red spectrum with only a small fraction of the applied power producing the useful visible light. As the power applied to the lamp is increased, the filament temperature increases somewhat less than proportionately while the useful visible light increases very rapidly as described by the Stefan-Bolzman law.sup.2 of thermal radiation which states that "the power emitted from a black body thermal source is proportional to the fourth power of its absolute temperature."
Increasing the power applied to an incandescent lamp increases the filament temperature which accelerates the filament material evaporation rate. As the filament material evaporates with lamp usage, the filament strength deteriorates which ultimately leads to filament failure..sup.3 Additionally, the evaporated filament material becomes deposited on the relatively colder inside wall of the glass envelope blocking the transmission of the light produced by the filament. Long life incandescent lamps can also fail due to filament embrittlement rather than filament evaporation. As tungsten filaments are heated for long periods of time, the filament crystalline structure changes from a random long grain flexible structure to a more rigid short grain structure like glass. This change in the filament material structure to the more rigid short grain structure is commonly referred to as the filament notching effect. Even a slight vibration or shock can cause a notched filament structure to fracture and fail. It has been found that AC lamp operation decreases the filament notching effect two to ten times over that obtainable with pure DC operation. Rectified and unfiltered AC operation offers a compromise in filament life improvement between AC and DC operation as a result of the AC component which is superimposed on the average DC value..sup.4
All batteries which are commonly used in flashlights exhibit a loss of voltage output as the battery capacity is consumed with usage. The degree of the voltage loss varies with the type of battery chemistry and electrical load, however, the general shape of the battery voltage output function is relatively similar for all of the types of batteries typically used in flashlights. Fresh battery voltage output begins at a maximum, then drops quite quickly during the first part of the discharge cycle and then slows to a gradual decline for the bulk of the battery capacity. As the battery approaches its end-of-useful life, the voltage reduction rate increases continuously until the rate becomes precipitous at the end-of-life. Battery output voltage is also affected by the battery temperature, especially in the colder regions of operation. From room temperature downward the battery output voltage falls and at the same time the battery internal resistance increases compounding the reduction of the net available battery capacity. In addition, battery voltage output is also affected by the electrical load, and to a lesser extent the battery age, duty cycle, and recovery time.
As an example of typical voltage loss with usage, manganese-alkaline batteries under moderate load at room temperature provide approximately 1.25 volts per cell output when fresh and less than 0.7 volts per cell when the battery capacity nears exhaustion. An incandescent lamp of the type used in flashlights when powered directly by such a manganese-alkaline battery over the life of the battery exhibits a decrease of 7:1 in the light output, a decrease of 3:1 in the power to light conversion efficiency, and a decrease of 1:380 in the incandescent lamp wear out rate.
Room temperature incandescent lamp cold filament resistance is typically only 1/6th to 1/20th of that at the normal operating temperatures..sup.5 When power is first applied to a miniature incandescent lamp, a large current in-rush transient lasting typically only a few milli-seconds occurs which decays quickly as the lamp filament temperature rises to its normal operating value. The peak value of this in-rush current surge is usually somewhat less than would be indicated by the lamp cold-to-hot filament resistance ratio as the battery internal resistance and conductor inductance typically constrain the current delivery capability. In practice, flashlight in-rush currents have been measured to be in the range of 3-10.times. higher than the steady-state levels. Every time that a flashlight is turned-on, the in-rush current surge thermally shocks the lamp filament weakening the filament structure. The damage to the filament structure produced by the thermal shock is cumulative and can become the dominant lamp failure mechanism if frequent power-on cycling occurs. In addition to lamp life reduction, the large in-rush current transients also increase the current carrying demands placed on the power switch which can become quite costly if high product reliability is required.
The above described shortcomings with respect to current flashlight light generation efficiency and component reliability have been understood from the beginning, however it is only recently that the availability of low cost electronic components has made invention of power supply regulation circuits for improving flashlight performance commercially feasible.
3. Incandescent Lamp Performance.sup.6
The total light output of a miniature incandescent lamp in the visible region has been found through experimentation to be a function of the applied and design voltages as described by the equation: ##EQU1## where: L=Light output at V volts applied to lamp.
L.sub.d =Light output at design voltage V.sub.d PA1 V=Voltage applied to lamp. PA1 V.sub.d =Lamp nominal design voltage. PA1 K.sub.f =Constant between 3.2-3.7 determined experimentally for the particular lamp design. A typical value of 3.5 for K.sub.f will be used in throughout this disclosure. PA1 I.sub.d =Current at the design voltage V.sub.d. PA1 K.sub.c =Constant between 0.52-0.57, determined experimentally for the particular lamp design. A typical value of 0.55 for K.sub.c will be used throughout this disclosure. PA1 E.sub.avg =Average Efficiency
The corresponding relationship for lamp current has been found to be: ##EQU2## where: I=Current at V volts applied to lamp.
Multiplying both sides of Equation 2 by V/V.sub.d provides the expression for lamp power P with V.sub.r defined as the ratio of V/V.sub.d thereby normalizing the expression to the lamp nominal design voltage: EQU P.varies.V.sub.r !.sup.(1+K.sbsp.c.sup.) ( 3)
Dividing both sides of Equation 2 by V.sub.r according to Ohm's law provides the lamp filament resistance R: EQU R.varies.V.sub.r !.sup.(K.sbsp.c.sup.-1) ( 4)
Dividing light output Equation 1 by power consumption Equation 3 yields the light output efficiency E, proportional to Lumens/Watt: EQU E.varies.V.sub.r !.sup.(K.sbsp.f.sup.-K.sbsp.c.sup.-1) ( 5)
And lamp filament life had been found through experiments to obey the following proportionality: ##EQU3## where: J=An exponent constant in the range of 10-13 for the type of miniature incandescent lamps used in flashlights. A value of 12 for J will be used throughout this disclosure.
Substituting typical values for small incandescent lamp of 3.5 for K.sub.f and 0.55 for K.sub.c into the Efficiency Equation 5 results in: EQU E.varies.V.sub.r !.sup.1.95 ( 7)
Substituting typical value for small incandescent lamp of 12 into the Lamp Life Equation 6 results in: ##EQU4## The importance of incandescent lamp voltage regulation can be seen from Equations 7 and 8 which show that incandescent lamp light output efficiency increases at nearly the second power of the applied to design voltage ratio while life decreases at the 12th power of the same ratio.
4. Current Flashlight Performance
A representative flashlight design powered by the most commonly used manganese-alkaline batteries will be described to illustrate current flashlight performance. Subsequently, the current flashlight performance will be compared with a flashlight design using the present invention.
FIG. 1 shows the normalized voltage output curve of a manganese-alkaline battery of a conventionally designed flashlight when that battery is discharged by the direct connection to an incandescent lamp load. The 100% value on the vertical axis indicates the lamp nominal voltage operating point. Current flashlight design practice entails the use of a lamp with a nominal voltage rating which is somewhat lower that the fresh battery output voltage. Although this design practice increases the risk of premature lamp burn-out due to excess voltage when the batteries are fresh, the counterbalancing benefit realized is a substantial improvement in the average lamp output efficiency over the life of the battery as a result of the increased fraction of battery capacity that is discharged more closely to the incandescent lamp nominal voltage operating point.
The battery voltage discharge function shown in FIG. 1 has been derived from a battery manufacturer's.sup.7 "D" cell constant load discharge specification together with Equation 4 which is used to factor in the non-linear resistance characteristics of the incandescent lamp filament. Application of Equations 1, 2, 3, and 5 to the battery voltage output function yields the lamp light output, lamp current, lamp power, and light to power conversion efficiency functions respectively, which are also shown plotted in FIG. 1 with all values normalized to equal 100% at the lamp nominal voltage operating point.
The relatively rapid decline of the light output function with respect to the battery voltage function is the result of the 3.5 power exponent in Equation 1 which becomes applied to the instantaneous battery output voltage. The Lumens/Watt power conversion efficiency function declines somewhat more slowly than the light output function as the lamp power consumption also declines somewhat with the declining battery output voltage. The average of the battery-lamp power conversion efficiency over the life of the battery is indicated by the horizontal line. The difference between 100% power conversion efficiency of an ideal design and the average power to light conversion efficiency of the conventionally designed manganese-alkaline battery powered flashlight defines the theoretical maximum light production improvement opportunity that might achieved with improved voltage control: ##EQU5## where: I.sub.opp =Maximum Improvement Opportunity
For the manganese-alkaline flashlight design example presented in FIG. 1, the average power to light conversion efficiency was shown to be 63%. Substituting that average power to light conversion efficiency into Equation 9 shows that theoretical maximum opportunity for power to light conversion efficiency improvement with improved voltage control is therefore 58%.
5. Prior Art
A voltage regulating circuit to permit constant light output level to be efficiently produced from an incandescent lamp over a wide range of source voltage is disclosed in U.S. Pat. No. 4,230,970. This regulating circuit is described as producing voltage regulation within +/-0.5% over an input voltage range of 6 to 12 Volts by the controlled periodic application of the full source voltage to the incandescent lamp. This regulating circuit utilizes an analog circuit method for providing a mathematical function which controls the timing of a pulse width modulated constant frequency voltage pulse train which is applied to the incandescent lamp. The on-fraction of the pulse width timing is established by the time required for the charging of a timing capacitor to a pre-set constant voltage level by the varying voltage source. When the voltage on the timing capacitor reaches the constant pre-set voltage level, the voltage applied to the lamp is turned-off and the timing capacitor is then discharged. The off-fraction of the pulse train applied to the lamp is determined by the difference between a free-running oscillator time period and the time used for the charging of the timing capacitor.
Another regulating circuit to permit relatively constant light level to be efficiently produced by an incandescent lamp over a wide range of source voltage is disclosed by U.S. Pat. No. 4,237,405. This regulating circuit shares many similarities with the regulating circuit in U.S. Pat. No. 4,230,970 above, varying primarily in the design of the circuit used for the charging and discharging of the timing capacitor and by the replacement of the free-running oscillator with a relaxation oscillator. This circuit is also described as producing regulation within .+-.0.5% over an input voltage range of 6 to 12 Volts.
Another regulating circuit to permit constant light level to be efficiently produced from an incandescent over a wide range of source voltage is disclosed by U.S. Pat. No. 4,499,525. This regulating circuit has several similarities to the two U.S. Pat. Nos. 4,230,970 and 4,237,405 discussed above including the use of pulse-width application of the full source voltage to the lamp to produce constant RMS power and the use of a timing capacitor for the establishment of the pulse train duty cycle, but differs in the design of the timing capacitor charging and discharging circuit and the oscillator circuits. This regulating circuit utilizes three forward biased diode junctions in series for the establishment of the constant pre-set voltage level used for setting the triggering level of the timing capacitor. The triggering function is implemented with two transistors which, in combination with the forward drop across the three diodes, establish the capacitor voltage triggering level that in turn determines the RMS conversion accuracy. This method and apparatus is shown through measurements to produce regulation within .+-.7% over an input voltage range of 3 to 6 Volts.

High-efficiency incandescent lamp power controller


Methods for determining the probability of a human observer correctly performing a visual discrimination task of a target with a dynamic image stream, movie, are based on the V50 criterion, or the number of resolvable cycles needed by the human observer for a fifty percent probability of discrimination task completion, for performing the same visual discrimination task of the same targets in static scenes given an infinite amount of time. Once the V50 value is determined for the target set using static images, this value is used with the resolvable cycles V of the target set from the movie in an empirical Target Transfer Probability Function TTPF defined by P∞(t)=(V(t)/V50(t))1.5/(1+(V(t)/V50(t))1.5). The TTPF calculates the probability of correctly performing the visual discrimination task of a target at a given instance in time within the movie. These P∞ values are then modified by a time limited search equation.

Accurate predictions of a human observer's performance, in terms of not only range at which the human will detect, classify, recognize, or identify a target but also how long it takes to accurately detect, classify, recognize, or identify a target while using electro-optical and forward looking infrared (FLIR) systems are important for several reasons. These predictions are guides for system designers and developers since predictions can be made on theoretical systems prior to manufacture to determine if they are expected to meet performance specifications. The predictions also allow purchasers of systems a way to evaluate manufactured systems for the same purpose. Finally, war game simulations and tactical decision aids use these predictions in order to evaluate engagement tactics. Therefore it is important to accurately model the range and amount of time required for a human to perform a visual discrimination task such as detecting, classifying, recognizing, or identifying a target.
The primary modeling technique for resolution and sensitivity requirements known in the prior art is the Vollmerhausen Targeting Task Performance (TTP) metric. The TTP metric uses several parameters to accurately model the environment, the imaging system (from entrance optics of the imager through the display), and also incorporates a numerical approximation of Barten's eye Contrast Threshold Function (CTF) to represent the human observer. The TTP metric is then multiplied by the angle subtended to the eye of the target and yields the psychophysical quantity of resolvable cycles (V). These resolvable cycles were used to develop an empirical Target Transfer Probability Function (TTPF). The TTPF then predicts the probability of task completion (detection, classification, recognition, identification) for a particular target or target set at various ranges with some confidence.
The original TTP metric was developed to predict a human observer's ability to detect and identify military vehicles at long ranges, >1 km. At this range, a typical advanced tactical sensor with a 50 μm pixel integrated a space of more than 0.2 m2, which was sufficient when discussing large vehicles, >3 m long. The other assumption of a static scene was also sufficient since most vehicles were either static or moving slowly (in angular velocity) into an attack posture. While this worked well for characterizing human visual discrimination performance for identification of large objects that were either stationary or moving slowly at a large range, it is insufficient for objects moving at moderate speeds and close range or objects which may be rotating and thereby changing their profile to the imaging system. When research into modeling the detection and identification of humans and handheld objects commenced, it became apparent that the tactical range had dramatically shifted from kilometers to hundreds of meters. It is predominately this short range that renders the static observer/static target assumption invalid. An observer moving at only 30 mph will cover a 500 m range in less than 1 minute.
To compensate for this limitation most war gamers assume that a target is static and randomly distributed in aspect to the imaging system and the time to make a higher level visual discrimination decision, such as classification or identification, is assumed to be an instantaneous event. The difficulty of an observer to classify or identify a randomly aspect distributed target is the cycle criterion for the TTPF (V50). This V50 is the number of resolvable cycles required to correctly detect, classify, recognize, or identify a target with 50 percent probability. This cycle criterion is reported for a number of different target sets but remains as an average over the predefined aspects a target may assume in the environment. In an attempt to determine the V50 for either a moving imaging system or a non-stationary target, experiments are being conducted using movies, which has led to an order of magnitude increase in the generation and storage of imagery causing monetary resources to be used for computer memory upgrades. The time to make a higher level visual discrimination decision, such as classification or identification, is usually measured but rarely reported.
The primary technique for modeling the temporal response of a human is known in the prior art as the Edwards-Vollmerhausen Time Limited Search (TLS) model. The TLS model uses the known probability of detection for a target given an infinite amount of time (P∞) to predict the actual probability of human observers if they do not have an infinite amount of time to search an image or scene. The cumulative probability of finding a target within time t is calculated using an exponential buildup curve equation. The mean time to detect the target is a calibrated parameter which varies due to scene complexity and image quality, but is a function of P∞. This TLS equation was developed for and strictly applied to the task of detecting targets. Many war gamers assume the task of classifying, recognizing, or identifying targets is an instantaneous event. This assumption could allow for an over prediction in the effectiveness and speed of an engagement involving imaging systems. A human observer may delay in making an identification simply because the target may be moving or turning in hopes of obtaining a better/easier aspect on which to make their decision. This delay in identification affects the temporal speed of a possible engagement and could cascade through an entire war game simulation.
In light of the above, the objectives of the present invention are to provide: a method for predicting the probability of detection, classification, recognition, and identification of either stationary or moving targets with a either a stationary or moving imaging system; a method which can be calibrated from more cost efficient static image experiments; finally a method which can be applied to mono-chrome or gray scale visible spectrum imagery, short-, mid-, and long-wave infrared spectrum imagery.

Method for modeling human visual discrimination task performance of dynamic scenes

THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARTY OF THE ARMY


A surface acoustic wave device includes a piezoelectric substrate, an interdigital electrode pattern, and a resistor thin film. The piezoelectric substrate has a piezoelectric effect. The interdigital electrode pattern is made of a conductive thin film and formed on the piezoelectric substrate to perform conversion between an electrical signal and a surface acoustic wave. The resistor thin film is formed on the piezoelectric substrate to electrically connect the piezoelectric substrate to the interdigital electrode pattern. The resistor thin film serves to remove charges from a surface of the piezoelectric substrate due to a pyroelectric effect to the interdigital electrode pattern.

The present invention relates to a surface acoustic wave (SAW) device and, more particularly to an SAW device in which noise caused by the pyroelectric effect of the piezoelectric substrate is suppressed.
In general, an SAW device such as an SAW filter has appropriately weighted interdigital transducers (IDTS) as input/output transducers on the surface of the piezoelectric substrate to perform conversion between an electrical signal and an SAW. In the conventional SAW device, an IDT pattern is merely formed of a conductive thin film on the piezoelectric substrate.
FIG. 3A shows an example of a conventional SAW device, and FIG. 3B shows the device of FIG. 3A along the line 3B--3B. As shown in FIGS. 3A and 3B, in the conventional SAW device, merely the pattern of IDTs 22 and 22' is directly formed of a conductive thin film on a piezoelectric substrate 21.
In the conventional SAW device shown in FIGS. 3A and 3B, when the ambient temperature changes, the surface of the piezoelectric substrate 21 is charged due to the pyroelectric effect of the piezoelectric substrate 21. When an electric field formed by the charges becomes equal to or more than the dielectric breakdown of the surrounding atmosphere of the piezoelectric substrate 21, the charges on the piezoelectric substrate 21 are discharged to the IDTs 22 and 22'.
If the charges are discharged to the ground-side IDT 22', the problem of noise does not occur in the SAW device. However, if the charges are discharged to the hot-side IDT 22, noise occurs in the SAW device.
In the latter case, the charges on the surface of the piezoelectric substrate 21 are not discharged unless they become equal to or more than the dielectric breakdown of the surrounding atmosphere of the piezoelectric substrate 21. Thus, the amount of charges removed at once becomes large to increase the noise level.
In particular, in an SAW device that uses lithium tantalate (LiTaO.sub.3) or lithium niobate (LiNbO.sub.3) as the material of the piezoelectric substrate 21, the piezoelectric substrate 21 has a strong pyroelectric effect, and the above drawback is remarkable.

Surface acoustic wave device with a resistor thin film to remove pyroelectric effect charges


Antenna assemblies for magnetic resonance signals comprise a non-resonant loop antenna and a high impedance differential amplifier. The amplifier can include first and second high electron mobility transistors that have gates coupled to an antenna loop that is defined on a rigid substrate. The non-resonant loop has an effective length of less than about 1/10 of a wavelength of a signal to be detected. Arrays of such loops can be defined on the rigid substrate, and HEMTs for the loops secured to the substrate.

RF coils for magnetic resonance imaging, spectroscopy, and other magnetic resonance applications have typically been based on conventional resonant and predetermined impedance transformation designs ('tune and match', tank circuit types) such as described in, for example, Roemer et al., "The NMR Phased Array," Magn. Reson. Med. 16:192-225 (1990). However, the electronic decoupling of multiple coils of such tuned designs in a parallel acquisition array remains a significant engineering problem. In addition, such tuned coils (or sets of such coils) are generally unable to detect two different nuclides in one MR scanning session, and different coils may be needed due to the different Larmor frequencies associated with different static magnetic field strengths.

High impedance differential input preamplifier and antenna for MRI

The State of Oregen Acting by and through the State Board of Higher Education on Behalf of the University of Oregon


A system for monitoring equipment and transmitting data and/or signals from one or more satellite nodes to a base node for transmission to a monitor or controller for the equipment. The system may transmit high frequency acoustic signals from one or more satellite nodes embedded in the equipment through a structural component of the equipment to the base node, eliminating the need to hardwire the satellite nodes in harsh environments.

Sensors are typically used in connection with performing monitoring, diagnostics, lifing, and control operations of large pieces of equipment such as gas, steam, and wind turbines, generators, and boilers. Such equipment typically resides in harsh, limited access environments. A major barrier to the wider deployment of new sensors in such environments is the need to install separate power and signal wire conduits for each sensor individually. Signal and power wires are expensive to install in power generation applications, since they must survive for long periods of time in harsh environments, and often must be certified for use in potentially hazardous environments. This increases the cost and therefore the ability to deploy advanced sensing technologies in such environments. Radio frequency based wireless communication solutions are expensive, and not well suited to harsh environments.

Acoustic methods for sensor communication


An apparatus for fabricating three-dimensional nonwoven fabric structure is disclosed, which includes an adjustable frame, a three-dimensional mold, a rotary shaft connecting the three-dimensional mold and the adjustable frame, and a meltblown device. The three-dimensional mold is rotated relative to the adjustable frame. The meltblown device has plural nozzles for spinning a plurality of fibers, wherein the three-dimensional mold is rotated in front of the nozzles to select the fibers, and a three-dimensional nonwoven fabric structure is formed on the three-dimensional mold.

1. Field of Invention
The present invention relates to an apparatus for fabricating three-dimensional nonwoven fabric structure. More particularly, the present invention relates to an apparatus for fabricating three-dimensional nonwoven fabric structure by using meltblown process.
2. Description of Related Art
With the rapid development of the textile industry, a variety of textiles have been utilized in our daily life. The conventional textiles, such as clothing, hats, socks, etc., need to be cut, sewn, or bonded while processing, therefore there must be some seams on the textiles and would spend much time.
A three-dimensional nonwoven fabric structure has been produced to provide a seamless product, but the thickness uniformity and the yield are difficult to improve.
For the forgoing reasons, there is a need for improving the thickness uniformity and the yield of the seamless three-dimensional nonwoven fabric structure.

Apparatus and method for fabricating three-dimensional nonwoven fabric structure


The self-lubricating bearing suitable for marine applications, such as supporting hatch covers, has a bearing surface defined by a flexible woven pad. This woven pad is draped over a pillow plate and captured in position by a sheet metal member which is folded over and thus engages the edge regions of the pad. The sheet metal member is affixed to the pillow plate and an underlying base plate.

1. Field of the Invention
The present invention relates to the provision of support for very large and heavy loads while simultaneously permitting limited movement of such loads in response to applied forces, and particularly forces which are exerted in directions which vary. More specifically, the present invention is directed to bearings which are suitable for use in a marine environment and especially to replaceable bearings which are capable of supporting hatch covers. Accordingly, the general objects of the present inventions provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use as a bearing on which a hatch cover of a sea-going vessel may be supported. Such hatch covers are often extremely large and, in the case of vessels designed to transport containerized cargos, loaded containers may be stored both in the ship's hold beneath the hatch cover and on top of the hatch cover. Hatch covers are customarily supported on pads which are provided on the ship's coaming. These pads contact the underside of support members provided on the peripheral portion of the hatch cover. The load being supported by the pads may be extremely large because of the size and weight of the hatch cover itself and, as noted above, because of the fact that containerized cargo will customarily be stacked on top of the hatch cover.
When a ship is in motion, as a result of wave action, the coaming will try to move relative to the hatch cover and, accordingly, forces will be applied to the hatch cover. In order to keep the forces applied to the cover within safe limits, i.e., to prevent hatch cover damage, a limited amount of relative motion between the cover and the coaming must be accommodated. Additionally, the ingress of salt water into the hold of the vessel in regions between the support pads must be prevented. The required weathertight seal is accomplished through the use of an elastomeric seal which is located about the underside of the perimeter of the hatch cover. The means by which the hatch cover is supported, in addition to permitting relative motion as discussed above, must also insure the integrity of the seal by maintaining the height of the gap to be sealed within design limits.
In the prior art the interface between a hatch cover and the cooperating support pads has been metal-on-metal. Relative sliding movement between the hatch cover and coaming in response to pitch and roll of the ship has resulted in excessive wear of the planar contact surface of the pads and particularly galling. Such surface wear, in turn, increases the possibility that the hatch cover will bind on the pad and stresses will thus be applied through the pad to the hatch cover causing structural damage. In addition, wear of the surfaces of the contact pads may result in failure of the hatch cover seal, i.e., the seal may be subjected to excessive compression and will thus fracture. Hatch cover seal failure is a major concern, particularly for vessels registered in the U.S., since the seals are tested while in a U.S. port by being subjected to a high pressure stream of water. The penalty for ineffective hatch cover seals, because they present the possibility of hold flooding with calamitous results, is loss of license. Repair or replacement of hatch cover support pads and a damaged hatch cover or hatch cover seal resulting from pad wear is, of course, a time consuming and expensive endeavor. Maintenance of hatch cover support pads is difficult since container vessels are typically in port only long enough to unload and reload and repairs and maintenance must be performed around the load/unload activities and within its time frame. Even when a vessel is dry docked for major repairs, the replacement or repair of the metallic hatch cover support pads is a time consuming, complex and expensive task.


The invention provides a novel scanning control system of preventing any over-scanning involved in an ion-implantation apparatus accomplishing an electrostatic X-scanning and a mechanical Y-scanning. The system includes a liner detecting arrangement for detecting over-scanning comprising a horizontal and sequential alignment of plural Faraday tubes. The detecting arrangement having a larger length than a diameter of a wafer is located behind the wafer mounted on a platen. The system also includes an X-scanning width control feature which is electrically connected to the detecting arrangement to fetch results of over-scanning detection. The X-scanning width control feature is determinative of a frequency of X-scanning associated with a width of X-scanning and supplies X-scanning frequency control voltage signals to X-deflector electrode plates making a pair thereby preventing over-scanning. The system further includes a Y-scanning speed control feature for controlling a speed of Y-direction movement of the wafer according to the frequency of the X-scanning thereby securing an uniformity of ion-implantation to the wafer.

The invention relates to an ion-implantation apparatus of a sheet type, and more particularly to an ion-beam scanning control feature involved in an ion-implantation apparatus of a parallel scanning type which accomplishes an electrostatic X-scanning of an ion-beam and mechanical Y-scanning.
In general, the sheet type of ion-implantation apparatus has been used for ion-implantation in a medium current region. Such sheet type ion-implantation apparatus may be divided into the following two types. One is an electrostatic scanning type of ion-implantation apparatus which accomplishes X-electrostatic scanning and Y-electrostatic scanning of ion-beams at predetermined frequencies respectively. Another is a parallel scanning type ion-implantation apparatus which accomplishes X-electrostatic scanning of the ion-beam and mechanical Y-scanning at predetermined frequencies respectively.
In the prior art, such a parallel scanning type of ion-implantation apparatus has the following structures. With reference to FIG. 1, the conventional structure of the ion-beam scanning control feature involved in the parallel scanning type ion-implantation apparatus has a platen 2 on which a wafer 1 is provided. The platen 2 is supported by a Y-scanning feature 3 so as to be movable in the vertical direction, or Y-direction thereby accomplishing the mechanical Y-scanning in the vertical direction.
In contrast to such a mechanical scanning in the Y-direction, the ion-beam 5 scans in the X-direction at a predetermined frequency (typically about 500 Hz) in the horizontal direction, controlled by an electrostatic scanning system which employs a pair of X-deflector electrode plates 4. Further, such a conventional structure of the ion-beam scanning control includes two Faraday tubes 6 serving as detecting elements, which are arranged at diametrically opposite sides approximately and behind the platen 2. The Faraday tubes 6 are supported to be in separation from the platen 2 which is movable in the vertical direction. Faraday tubes 6 catch the ion-beam and makes a measurement of a current generated by the ion-beam 5.
The operation of the ion-beam scanning control feature involved in the parallel scanning type ion-implantation apparatus will be described with reference to FIG. 1. The ion-beam 5 is transmitted to the wafer 1 on the platen 2 via a space defined by a pair of the X-deflector electrode plates 4. The ions having a predetermined average energy supplied by the ion-beam 5 are implanted into the wafer 1. The X-scanning of the ion-beam 5 has a predetermined frequency which is controlled by voltage signals applied to the X-deflector electrode plates 4. The Y-scanning feature 3 moves the platen 2 on which the wafer 1 is supported in the Y-direction, or vertical direction thereby accomplishing the mechanical Y-scanning.
The problem with such X-scanning by the ion-beam 5 is an over-scanning which provides unnecessary ion-beams to which external area and thus an opposite areas beyond the surface of the wafer 1 is subjected. To prevent such over-scanning, the conventional apparatus includes a feature for detecting the over scanning. In the X-scanning controlled by a pair of the X-deflector electrode plates 4, if there is any over-scanning of the ion-beam 5, which has a larger scanning width than the diameter of the wafer 1, the Faraday tubes 6 catches the over-scanning ion-beams. Hence, the Faraday tubes 6 detect the over-scanning. When the over-scanning of the ion-beam 5 is detected by the Faraday tubes 6, voltage signals are applied to a pair of the X-deflector electrode plates 4 which provide a predetermined scanning frequency. The scanning frequency provided by such X-deflector electrode plates 4 is determinative of the scanning width of the ion-beam 5 in the X-direction, or the horizontal direction so as to limit the scanning width of the ion-beam 5 to the diameter of the wafer 1 supported on the platen 2. As a result, such scanning ion-beam 5 has an uniformity in the X-scanning width which is defined by the distance between the two Faraday tubes 6.
Although the wafer 1 is circular, such a scanning area of the ion-beam 5 is defined into a square to internally touch the circle defined by the wafer 1. Since the wafer 1 which is subjected to the ion-implantation is circular, such conventional ion-beam scanning having the uniformity in the X-scanning width and thus having a square ion-implantation area is forced to have unnecessary over-scanning of such square area. Then, four corner areas in the square ion-implantation area except for an overlapping area to the wafer is subjected to the over-scanning of the ion-beam. It is, therefore, necessary to develop a novel scanning control feature which is free from any over-scanning, or unnecessary scanning. Further, such over-scanning to the external area to the wafer requires an unnecessary time for an ion-implantation process. It is, thus, desirable to prevent any over-scanning.

Scanning control system involved in an ion-implantation apparatus


A watering nozzle assembly includes a core tube received in the barrel of the nozzle. A first seal ring and a second seal ring are respectively mounted to a second end of the core tube, and a plurality of apertures are defined radially in the core tube and located between the first and second seal rings. A control rod pivotably connected to an operation bar movably seals the first end of the core tube. A nozzle is threadedly connected to the core tube. A block is fixedly connected to the second end of the core tube and removably seals the nozzle. The nozzle cab be moved relative to the core tube to allow water flowing from the gap between the block and the stepped surface in the nozzle. The first and second seal rings ensure that the nozzle assembly does not leak whichever status it is operated.

A conventional watering nozzle assembly is shown in FIGS. 7 and 8 and generally includes a connector 80 with a first threaded inner periphery 81 so as to be connected with a hose or the like, and a threaded outer periphery 84 is defined in an outer periphery of the connector 80 so as to be threadedly connected to a second threaded inner periphery 91 of a nozzle 90. A first seal ring 82 and a second seal ring 83 are mounted to the connector 80 and located such that the first threaded inner periphery 84 is located between the two seal rings 82, 83. The nozzle 90 includes a diverse outlet 92 and a stepped surface 93 is defined in an inner periphery of the nozzle 90. A block 200 is fixed to a distal end of the connector 80 by a screw 300 which extends through the block 200 and is threadedly connected to a recess 86 in the connector 80. A seal plate 100 is attached to an inside of the block 200 and can be matched with the stepped surface 93 to seal the outlet 92 as shown in FIG. 7. When rotating the nozzle 90 away from the connector 80 as shown in FIG. 8, water flows out from the outlet 85 of the connector 80 and passes through the gap between the block 200 and the stepped surface 93.
The nozzle 90 has to be rotated to tightly contact the sealing plate 100 against the stepped surface 95, or leakage may happen and this action requires a lot of efforts and might not be suitable for kids or users who do not have strong muscles.
The present invention intends to provide a watering nozzle assembly which includes two sealing mechanism to ensure the sealed status.

Sealing device for a watering nozzle assembly


A motor vehicle lock, in particular for a vehicle rear door, having a lock cover and a locking mechanism consisting essentially of a rotary latch and at least one pawl, also comprising at least one coupling element, and at least one electric drive, wherein the coupling element can assume different positions, and the coupling element interacts with a drive element of the drive and a central locking mechanism, wherein the coupling element is connected to the drive element in order to take up its positions.

A motor vehicle latch of the type described at the outset is usually attached to a motor vehicle door on one side and interacts with a vehicle body-side locking bolt. Furthermore, the arrangement may, however, also be the other way around so that the closure bolt is arranged on the motor vehicle door and the latch is arranged on the motor vehicle.
Such motor vehicle latches are equipped with a central locking mechanism and usually comprise different positions and functions associated with those positions. In this case, it is conceivable for the positions of the coupling element to be adjusted by means of the drive. Such motor vehicle latches are known from DE 199 43483B4, for example. Here, an anti-theft module is formed on the one hand and a locking module is formed on the other hand. In addition, it is possible to lift the pawl by means of the anti-theft module either directly or, where applicable, by interposing a release lever.
However, the motor vehicle latches known in the art are disadvantageous in that the coupling element may not be reliably positioned by means of the drive element.
There is therefore the need to develop motor vehicle latches so as to develop a position of the coupling element and a functional position of the central locking mechanism such that the above problems are solved constructively and cost-effectively.


A force-feel system is implemented by mechanically coupling a servo-actuator to and in parallel with a flight control system. The servo-actuator consists of an electric motor, a gearing device, and a clutch. A commanded cockpit-flight-controller position is achieved by pilot actuation of a trim-switch. The position of the cockpit-flight-controller is compared with the commanded position to form a first error which is processed by a shaping function to correlate the first error with a commanded force at the cockpit-flight-controller. The commanded force on the cockpit-flight-controller provides centering forces and improved control feel for the pilot. In an embodiment, the force-feel system is used as the basic element of stability augmentation system (SAS). The SAS provides a stabilization signal that is compared with the commanded position to form a second error signal. The first error is summed with the second error for processing by the shaping function.

Helicopters are well known to be inherently unstable and therefore difficult to fly, especially in conditions of degraded visibility and when the air is turbulent. Large helicopters employ force-feel systems and stability augmentation systems (SASs) to improve flying qualities and thereby simplify the flying task. Force-feel systems and SASs are not offered on smaller helicopters because they are complex, heavy, and expensive.
FIG. 1 illustrates a conventional helicopter system 10 with a SAS that includes a force-feel system. The SAS includes a series servo-actuator 12, a trim-motor 14, a feel-spring 16, and a linkage 18 that is inserted between the pilot's cockpit-flight-controller 20 and the flight control surface 22. Thus, the SAS is implemented in series with the flight control system.
The forces felt by the pilot's hand on the cockpit-flight-controller 20 depend on the feel-spring 16 and trim-motor 14. The output of the trim-motor 14 controls the reference point for the feel-spring 16. The pilot controls the output of the trim-motor 14 by using a trim-switch (not shown) typically located on the cockpit-flight-controller 20. The input to the flight control surface 22 includes the sum of the position of the cockpit-flight-controller 20 via a link 24 and the series servo-actuator 12 via a link 26.
Signals transmitted by the SAS (i.e., SAS inputs) to the series servo-actuator 12 include angular rate and/or attitude feedbacks that are intended to damp or stabilize the motions of an unstable helicopter. The effect of the SAS inputs to the series servo-actuator 12 are transmitted to the flight control surface 22 via the mechanical linkages 18 and 26. The linkage 18 is designed so that SAS feedbacks are not felt by the pilot at the cockpit-flight-controller 20. The absence of any forces on the cockpit-flight-controller 20 due to the SAS inputs to the series servo-actuator 12 is an objective of the series implementation. The need for a complex flight control linkage 18, a trim-motor 14 and a feel-spring 16 make the series implementation of a force-feel system and SAS unsuitable for use on light helicopters due to excessive weight and cost.
It is difficult and costly to retrofit an existing helicopter with a conventional force-feel system or SAS. As illustrated by the linkage 18 in FIG. 1, conventional systems require that apparatus be inserted into a break in the existing flight control system. Unless a helicopter already has a series servo-actuator 12 and linkage 18 installed, this is a significant and costly modification. Typically, a series servo-actuator 12 and linkage 18 are found only in large and complex helicopters. For these reasons, conventional systems are not deemed suitable for installation in light helicopters.
FIG. 2 illustrates a conventional autopilot system 28 used on helicopters and airplanes. Compared to the system 10 shown in FIG. 1, the conventional autopilot system 28 utilizes a less-complex parallel servo-actuator 30 implementation. The servo-actuator 30 is mechanically attached directly to and in parallel with an existing flight control system without any modification to the linkage 24 between the cockpit-flight-controller 20 and the flight control surface 22. The servo-actuator 30 includes a gearing device and clutch assembly 32 and an electric motor 34. When the autopilot is engaged, the servo-actuator 30 moves the flight controls 20, 22, 24 to achieve a response commanded by an autopilot computer 40. High gear ratios are employed in the gearing device and clutch assembly 32 to reduce the size of the electric motor 34. The gearing device and clutch assembly 32 exhibits moderate freeplay in typical autopilot systems.
The combination of high gearing and freeplay results in heavy cockpit flight control forces and undesirable looseness in the controls if the pilot attempts to override the autopilot. Thus, the combination results in very objectionable handling qualities if the pilot attempts to control the vehicle manually with the autopilot engaged. Therefore, conventional force-feel systems and SASs designed to augment manual control employ the more complex series mechanization illustrated in FIG. 1.
The conventional autopilot system 28 shown in FIG. 2 may include an override spring (not shown) between the autopilot servo-actuator 30 and the cockpit-flight-controller 20. The purpose of the override spring is to allow the pilot to make minor corrections to the aircraft attitude or flight path without disengaging the autopilot, and to return to automatic flight without having to reestablish trim. The force vs. deflection gradient of the override spring must be sufficiently large so that the autopilot servo-actuator 30 can drive the cockpit-flight-controller 20 without introducing additional dynamics due to the override spring. However, such a large spring does not provide satisfactory control feel for a force-feel system or SAS where full time manual control is the objective. Another disadvantage of such systems is that a mechanism (not shown) is required to disconnect the override spring from the flight control system when the autopilot is turned off. Such a mechanism adds weight and must be carefully designed to ensure that it will not fail in a way that it cannot be disconnected from the flight control system. Thus, a mechanical spring is not deemed suitable as a means to provide a parallel force-feel system or SAS.
Tactile feedback enhances the control feel of aircraft. One of the feedbacks to the cockpit-flight-controller that can be used to accomplish improved tactile feel is the position of the cockpit-flight-controller itself. This is commonly done in fly-by-wire systems (not shown) where the flight controller is not mechanically connected to the flight control system. Rather, a flight controller in a fly-by-wire system transmits electrical signals to a servo-actuator which is connected in series, such as the servo-actuator 12 shown in FIG. 1. That is, by contrast to the system 10 shown in FIG. 1, a fly-by-wire system replaces the mechanical link 24 with an electrical connection (i.e., a wire) that transmits a signal directly to the servo-actuator 12. Some fly-by-wire systems replace the feel spring 16 in FIG. 1 with complex algorithms that are intended to improve the tactile feel of the cockpit-flight-controller 20. However, such systems are intended for complex, highly augmented, fly-by-wire aircraft and are not deemed suitable for use on light helicopters.

Helicopter force-feel and stability augmentation system with parallel servo-actuator


A method is provided for receiving a data frame in an ultrawide bandwidth network. In this method, a device receives an ultrawide bandwidth signal containing a data frame. The device then performs an acquisition operation during a first preamble in the data frame, and identifies a marker after the first preamble that indicates that the first preamble has ended. After this, the device performs a signal processing operation during a second preamble in the data frame. After the training, the device then receives a header in the data frame, and then receives a payload in the data frame. By having a marker between the two preambles, this method provides a receiving device with critical information regarding the timing of the preamble section of a frame.

In wireless communications standards individual wireless devices often send information back and forth between each other in the form of discrete frames sent in wireless signals. Each of these frames contains some information to be passed, as well as some information to allow the receiving device to properly receive and decipher the information in the frame.
Because of differences in local clock operation and variances in signal transmission paths, it is generally necessary for a receiving device to synchronize the phase of an internal clock with the phase of a received signal before the signal can be processed. In many implementations a frame will include a preamble that is placed at the beginning of the frame which allows the receiving device an opportunity to synchronize with the incoming frame. This is often called acquiring or locking onto the signal containing the incoming frame.
A preamble is generally a known, recognizable, and repeated pattern of bits that the receiving device can look for. This pattern is often generated by a formula known to both the transmitting device and the receiving device, and which can be easily detected.
In order to successfully identify the preamble, the receiving device must operate using a local clock that is synchronized with the phase of the incoming signal. As a result, in attempting to lock onto the incoming signal, the receiving device will generally vary the phase of its local clock, attempting to find a phase at which it can successfully detect the bit pattern in the preamble. Once the receiving device successfully identifies the preamble, i.e., recognizes the bit pattern being sent in the preamble, it will have successfully synchronized its local clock with the phase of the received data frame, and will have locked onto the bit pattern. In a wireless device there are generally several levels of synchronization. A device can synchronize to an oscillator frequency of the incoming signal, to a symbol or chip being sent in the incoming signal, or to a series of bits being sent in the incoming signal. Generally a device will have to sequentially synchronize on increasing levels of the signal, building upon the synchronization with the lower levels.
In implementation, most devices that use preambles do not initialize the formula (e.g., the polynomial) used for generating the preamble to the same initial conditions in every frame. In other words, while a preamble will generally contain a known and repeated bit pattern, the start of that bit pattern will be essentially random with respect to the start of the preamble. As a result, once the receiving device successfully synchronizes with an incoming preamble, it has no way of knowing how much time remains before the preamble ends.
In a narrow band system, a receiver can use a carrier (i.e., energy) detection to determine when a preamble starts, and thus how much time remains. In a UWB system, however, the signals have low signal-to-noise (SNR) ratio, meaning energy detection is generally an undesirable solution.
This can be a problem in certain devices that require additional signal processing or receiver preparation before receiving information from a frame. For example, some devices may perform operations on an incoming signal to improve signal quality. These operations can tale the form of linear equalization, decision feedback equalization (DFE), fine automatic gain control (AGC), and/or the use of RAKE receivers. These processes take a certain amount of time to train before they are ready to operate. And since the receiving UWB device does not know how much time remains in the preamble after signal lock, it cannot determine whether there is sufficient time remaining for receiver training, AGC refinement, signal normalization, or the like.
This can be a problem because if the receiving device starts training and the preamble ends before the training is completed, the receiving device may not be able to successfully receive the incoming data without an unacceptable number of errors. This can also be a problem in embodiments that continue to refine acquisition (e.g., using multiple acquisition fingers). In this situation, since the receiver doesn't know when the preamble will end, it doesn't know if it has sufficient time to try and look for a better acquisition lock before it must start training. It then runs the risk of either wasting too much time refining acquisition lock so that it has insufficient time for training, or it might stop refining acquisition too early in an effort to make certain it will have enough time for training.
Accordingly, it would be desirable in the art for a solution to the problems associated with unknown relative signal lock timing, and further to the problems associated with trying to allow adequate time for receiver training when a receiving device has no way of knowing the remaining time in a preamble once signal lock is completed.

System and method for passing data frames in a wireless network


A firearm receiver assembly that includes a magazine release assembly, a bolt release assembly, a safety switch assembly, and a charging handle assembly and wherein at least one of the magazine release assembly, the bolt release assembly, the safety switch assembly, and the charging handle assembly are ambidextrously operable from each of a right hand side and a left hand side of the resultant firearm.

Although some firearm users are ambidextrous and can efficiently and accurately operate right or left handed firearms, it is readily appreciated that many firearms are provided in right-hand and left-hand models. The respective hand nomenclature is used to designate use of the firearm by the respective dominant hand of the shooter being associated with the trigger and/or stock. Such a designation allows use of the shooters dominant eye for sighting and positions the controls associated with operation of the firearm, such as safeties, magazine catches, bolt catches and casing discharge openings for comfortable interaction and operation by the shooter. Providing firearms in right and left hand model constructions increases manufacturing costs and requires attention by consumers to a firearm having the appropriate or desired right handed or left handed construction.
In an effort to improve manufacturing efficiencies and provide more uniform product platforms, some manufacturers provide what have been termed ambidextrously operable firearms but some such firearms fail to adequately consider the orientation of the shooter and the shooters hands to the both the firearm and each of the controls associated with sustained operation of the firearm. Such considerations are more endemic in rifle configuration and particularly semi or fully automatic firearms wherein maintaining a visual target acquisition is commonly preferred or desired even during interaction with one or more of the controls associated with operation of the underlying firearm. In repeat fire rifle configurations, such controls can commonly include a safety selector, a bolt catch or release, a magazine catch or release, and operation of a charging handle to maintain a desired ready to discharge configuration of the underlying firearm.
As is commonly appreciated, the safety selector is commonly associated with a live position wherein discharge of the firearm is possible with subsequent actuation of the trigger and a safe condition wherein operation of the trigger is disabled or otherwise interfered with such that the trigger cannot be actuated even if a round is present in the chamber. The magazine catch or release secures a magazine relative to the receiver and is operable such that actuation of the magazine catch allows, removal of a magazine from the firearm and subsequent engagement of a replacement or reloaded magazine with the receiver.
The bolt catch or bolt release cooperates with the bolt and leaves the action open upon discharge of a last round such that, actuation of the bolt release closes the action in a manner wherein movement of the bolt into battery introduces a subsequent round of ammunition to the chamber from a replacement magazine. The charging handle cooperates with the bolt and allows the shooter to manually manipulate the position of the bolt for an open position to a battery position for activities such as cocking the hammer or firing pin, discharging an unspent or misfired cartridge, inspection of the bore, chamber or action, clearing a stoppage such as a jam or miss feed, and allows the action to be closed while simultaneous introducing a subsequent round.
Interaction with one or more of the control functions described above can be rendered physically awkward or difficult depending on the orientation of the control relative to the dominant hand of the shooter. Many self asserted ambidextrously operable firearm assemblies fail to include ambidextrous controls for each of the operational structures of the firearm such that, during some instances, the shooter must attain a somewhat awkward position to interact with the respective control arrangement or even fully dissociate the firearm from a firing position to attain an orientation wherein the shooter can interact with the respective control arrangement. Such problems are exacerbated in instances of firearms configured primarily for right handed or left handed shooters and operated by the other of a right handed or left handed shooter.
Another concern associated with providing ambidextrous control of a firearm is associated with reducing the potential for inadvertent actuation of any given control arrangement. That is to say, some ambidextrously operable firearm control arrangements are provided in configurations wherein very limited deviation from a prescribed shooting position can result in inadvertent operation of one or more of the controls provided to accommodate shooters of the other dexterity. Such concerns can be exacerbated during combat situations where such undesired or unintentional interaction with one or more of the control arrangements configured for shooters of the alternate dexterity can have serious consequences to the efficacy of a present shooter.
Therefore, there is a need for a firearm that is constructed to be operated by right handed or left handed shooters and which provides ambidextrous interaction with each of the controls associated with operation of the firearm and does so in a manner that provides an orientation of the respective control inputs such that the respective "right hand" firearm controls do not interfere with or be inadvertently operable by left handed shooters, and vice versa.

Ambidextrously operable firearm receiver assembly


Disclosed is system for extracting tabular data from electronic document, system having data processing arrangement comprising: tabular data detection module that is operable to: (i) receive electronic document; (ii) determine location of tabular data within electronic document; and (iii) extract image of tabular data from electronic document; and tabular data extraction module that receives extracted image of tabular data from tabular data detection module, wherein tabular data extraction module is operable to: (i) convert received image of tabular data into greyscale image; (ii) extract grid structure from greyscale image; (iii) remove grid structure from greyscale image; (iv) determine position for placement of horizontal and vertical lines in greyscale image; (v) generate horizontal and vertical lines on greyscale image; (vi) perform optical character recognition of text associated with tabular data from received image; and (vii) extract tabular data by combining information of grid structure with text, to generate tabular data.

Nowadays, portable document format (PDF) has become an essential format for communication and transfer of documents containing data and information, among people involved with the use of the data and information. Generally, an analyst conducts analysis of documents pertaining to a field in which the analyst has proficiency and expertise. For example, a financial analyst conducts analysis of documents pertaining to finance. The documents used in analysis involve data and information in form of tables. For example, the data and information in form of tables can be annual reports, comparative analysis, timelines, and session agenda. The tables allow the analyst to easily visualize and compute the data and information.
Typically, the analyst performs the analysis on the document by extracting the data and information. The extraction of data and information involves detection of the data and information in the tables and retrieval of the data and information to a document of different file-formats (such as, a file generated by a word-processing file, a spreadsheet file and so forth). However, the extraction of data and information in the tables has several problems related to it. Firstly, the analyst faces problem with copy and paste of the tables of data and information, from document in PDF format to document of different file-format. For example, there can be loss of information during copy and paste. Secondly, the tables can also be lost during the process of extraction. As a result, the hierarchy that is initially maintained in the tables is lost during the extraction process. Thirdly, certain tables do not have definite vertical and horizontal lines for segregation of the data and information. Consequently, during the extraction of such tables, a pattern and a sequence of the data and information are lost. Therefore, the essence of the data and information in the tables is lost during their extraction.
Presently, several existing methods and tools are used for extraction of data and information in the tables. The existing methods and tools extract the data and information in tables, from PDF format to different file-formats. However, the existing methods and tools involve poor auto detection technology, as a result, the analyst has to manually select the tables containing the data and information which can be tiresome when the number of selections are large. Furthermore, the existing methods and tools perform the process of extraction one page at a time, as a result, extraction cannot be done one batch (group of tables on one or more than one pages) at a time. Also, the existing methods and tools are unable to extract data and information in multiple row lines or merged cells inside table. Additionally, the existing methods and tools have limitations on the number of pages and size of the document on which the process of extraction is performed. Furthermore, the existing methods and tools have limitations on the number of pages a single table can exist. Moreover, the extraction process using the existing methods and tools causes variation in the font of the data and information.
Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with extraction of data and information in form of tables within a PDF document.

System and method for extracting tabular data from electronic document


Addressing error detection systems and methods are disclosed. A target address is written to a memory in an electronic system and subsequently output on an address path through which the memory is addressable. An addressing error is detected by determining whether the target address output on the address path is detected at the memory. Address detection at the memory involves storing the target address, monitoring the address path for the target address, and providing an address detection indication based on whether the target address is detected on the address path. The address detection indication may be provided, for example, by setting a flag in a data structure which is stored in the memory.

Traditionally, checking for addressing errors such as address bus errors in electronic systems has largely been a lower priority than checking for data errors. However, in an effort to pursue maximum system reliability and availability, with respect to so-called "5-9's" carrier grade targets for instance, the need to detect all types of electronic system errors, including addressing errors, has become more important.
According to one electronic system error detection technique, a microprocessor writes data to a scratch pad register and then reads data from the same scratch pad register to verify an error-free data path between the microprocessor and the scratch pad register. However, this technique itself is susceptible to undetected addressing errors, in that an addressing error may affect both a write address and a subsequent read address. Thus, an incorrect register might be addressed during both write and read operations. In this case, the addressing errors would not be detected by the microprocessor.
Although other error protection techniques such as parity may be used to provide a level of protection against addressing errors, many system bus protocols which are employed within or between electronic systems or components thereof lack this kind of protection.

Addressing error and address detection systems and methods


Dendritic cells play a critical role in antigen-specific immune responses. Materials and methods are provided for treating disease states, including cancer and autoimmune disease, by facilitating or inhibiting the migration or activation of antigen-presenting dendritic cells. In particular, chemokines are used to initiate, amplify or modulate an immune response. In one embodiment, chemokines are used to attract dentritic cells to the site of antigen delivery. An increase number of dendritic at the site of antigen delivery means more antigen uptake and a modified immune response.

Dendritic cells (DC) specialize in the uptake of antigen and their presentation to T cells. DC thus play a critical role in antigen-specific immune responses.
DC are represented by a diverse population of morphologically similar cell types distributed widely throughout the body in a variety of lymphoid and non-lymphoid tissues (Caux, et al.,1995, Immunology Today 16:2; Steinman, 1991, Ann. Rev. Immunol. 9:271–296). These cells include lymphoid DC of the spleen, and lymph nodes, Langerhans cells of the epidermis, and veiled cells in the blood circulation. DC are collectively classified as a group based on their morphology, high levels of surface MHC-class II expression as well as several accessory molecules (B7-1[CD80] and B7-2[CD86]) that mediate T cell binding and costimulation (Inaba, et al., 1990, Intern. Rev. Immunol. 6:197–206; Frendenthal, et al., 1990, Proc. Natl. Acad. Sci. USA 87:7698), and absence of certain other surface markers expressed on T cells, B cells, monocytes, and natural killer cells.
DC are bone marrow-derived and migrate as precursors through blood stream to tissues, where they become resident cells such as Langerhans cells in the epidermis.
In the periphery, following pathogen invasion, immature DC such as fresh Langerhans cells are recruited at the site of inflammation (Kaplan, et al., 1992, J. Exp. Med. 175:1717–1728; McWilliam, et al., 1994, J. Exp. Med. 179:1331–1336) where they capture and process antigens, (Inaba, et al., 1986. J. Exp. Med. 164:605–613; Streilein, et al., 1989, J. Immunol. 143:3925–3933; Romani, et al., 1989., J. Exp. Med. 169:1169–1178; Puré, et al., 1990. J. Exp. Med. 172:1459–1469; Schuler, et al., 1985, J. Exp. Med. 161:526–546).
Antigen-loaded DC then migrate from the peripheral tissue via the lymphatics to the T cell rich area of lymph nodes, where the mature DC are called interdigitating cells (IDC) (Austyn, et al., 1988, J. Exp. Med. 167:646–651; Kupiec-Weglinski, et al., 1988, J. Exp. Med. 167:632–645; Larsen, et al., 1990, J. Exp. Med. 172:1483–1494; Fossum, S. 1988, Scand. J. Immunol. 27:97–105; Macatonia, et al., 1987, J. Exp. Med. 166:1654–1667; Kripke, et al., 1990., J. Immunol. 145:2833–2838). At this site, they present the processed antigens to naive T cells and generate an antigen-specific primary T cell response (Liu, et al., 1993, J. Exp. Med. 177:1299–1307; Sornasse, et al., 1992, J. Exp. Med. 175:15–21; Heufler, et al., 1988, J. Exp. Med. 167:700–705).
During their migration from peripheral tissues to lymphoid organs, DC undergo a maturation process encompassing dramatic changes in phenotype and functions (Larsen, et al., 1990, J. Exp. Med. 172:1483–1494; Streilein, et al., 1990, Immunol. Rev. 117:159–184; De Smedt, et al., 1996, J. Exp. Med. 184:1413–1424). In particular, in contrast to immature DC such as fresh Langerhans cells, which capture and process soluble proteins efficiently and are effective at activating specific memory and effector T cells, mature DC such as IDC of lymphoid organs are poor in antigen capture and processing but markedly efficient in naive T cell priming (Inaba, et al., 1986. J. Exp. Med. 164:605–613; Streilein, et al., 1989, J. Immunol. 143:3925–3933; Romani, et al., 1989, J. Exp. Med. 169:1169–1178; Puré, et al., 1990, J. Exp. Med. 172:1459–1469; Sallusto, et al., 1995, J. Exp. Med. 182:389–400; Cella, et al., 1997, Current Opin. Immunol. 9:10–16).
Signals regulating the traffic pattern of DC are complex and not fully understood.
Signals provided by TNFα and LPS are known to induce in vivo migration of resident DC from the tissues to the draining lymphoid organs (De Smedt, et al., 1996, J. Exp. Med. 184:1413–1424; MacPherson, et al., 1995, J. Immunol. 154:1317–1322; Roake, et al., 1995, J. Exp. Med. 181:2237–2247; Cumberbatch et al., 1992, Immunology. 75:257–263; Cumberbatch, et al., 1995, Immunology. 84:31–35).
Chemokines are small molecular weight proteins that regulate leukocyte migration and activation (Oppenheim, 1993, Adv. Exp. Med. Biol. 351:183–186; Schall, et al., 1994, Curr. Opin. Immunol. 6:865–873; Rollins, 1997, Blood 90:909–928; Baggiolini, et al., 1994, Adv. Immunol. 55:97–179). They are secreted by activated leukocytes themselves, and by stromal cells including endothelial cells and epithelial cells upon inflammatory stimuli (Oppenheim, 1993, Adv. Exp. Med. Biol. 351:183–186; Schall, et al., 1994, Curr. Opin. Immunol. 6:865–873; Rollins, 1997, Blood 90:909–928; Baggiolini, et al., 1994, Adv. Immunol. 55:97–179). Responses to chemokines are mediated by seven transmembrane spanning G-protein-coupled receptors (Rollins, 1997, Blood 90:909–928; Premack, et al., 1996, Nat. Med. 2:1174–1178; Murphy, P. M. 1994, Ann. Rev. Immunol. 12:593–633). Several chemokines such as monocyte chemotactic protein (MCP)-3, MCP-4, macrophage inflammatory protein (MIP)-1α, MIP-1β, RANTES (regulated on activation, normal T cell expressed and secreted), SDF-1, Teck (thymus expressed chemokine) and MDC (macrophage derived chemokine) have been reported to attract DC in vitro (Sozzani, et al., 1995, J. Immunol. 155:3292–3295; Sozzani, et al., 1997, J. Immunol. 159:1993–2000; Xu, et al., 1996, J. Leukoc. Biol. 60:365–371; MacPherson, et al., 1995, J. Immunol. 154:1317–1322; Roake, et al., 1995, J. Exp. Med. 181:2237–2247).
In recent years, investigators have attempted to exploit the activity of DC in the treatment of cancer. In an animal model, as few as 2×105 antigen-pulsed DC will induce immunity when injected into naive mice (Inaba at al., 1990, Intern. Rev. Immunol. 6:197–206). Flamand et al. (Eur. J. Immunol., 1994, 24:605–610) pulsed mouse DC with the idiotype antigen from a B-cell lymphoma and injected them into naive mice. This treatment effectively protected the recipient mice from subsequent tumor challenges and established a state of lasting immunity. Injection of antigen alone, or B cells pulsed with antigen, had no effect, suggesting that it was the unique characteristics of DC that were responsible for the anti-tumor response. It has been postulated that DC are not only capable of inducing anti-tumor immunity, but that they are absolutely essential for this process to occur (Ostrand-Rosenberg, 1994, Current Opinion in Immunol. 6:722–727; Grabbe et al., 1995, Immunol. Today 16:117–120; Huang et al., 1994, Science 264:961–965). Huang and coworkers (Huang et al., 1994, Science 264:961–965) inoculated mice with a B7-1 transfected tumor that was known to produce anti-tumor immunity. They demonstrated that only mice with MHC-compatible APC were capable of rejecting a tumor challenge. Studies in humans have demonstrated a similar role for DC. It has been reported that peptide-specific CTL are readily induced from purified CD8+ T cells using peptide-pulsed DC, but are not elicited when peptide-pulsed monocytes are used (Mehta-Damani et al., 1994, J. Immunology 153:996–1003).
Of significant clinical interest, the histologic infiltration of dendritic cells into primary tumor lesions has been associated with significantly prolonged patient survival and a reduced incidence of metastatic disease in patients with bladder, lung, esophageal, gastric and nasopharygeal carcinoma. In contrast, a comparatively poorer clinical prognosis is observed for patients with lesions that exhibit a sparse infiltration with DC and metastatic lesions are frequently deficient in DC infiltration (Becker, 1993, In Vivo 7:187; Zeid et al., 1993, Pathology 25:338; Furihaton et al., 1992, 61:409; Tsujitani et al., 1990, Cancer 66:2012; Gianni et al., 1991, Pathol. Res. Pract. 187:496; Murphy et al., 1993, J. Inv. Dermatol. 100:3358). A patient with advanced B-cell lymphoma was recently treated with DC pulsed with the patient's own tumor idiotype (Hsu et al., 1996, Nature Medicine 2(1):52). This produced a measurable reduction in the patient's B-cell lymphoma. Treatment of prostate cancer using DC pulsed with PSM antigen has been reported by Murphy et al. (The Prostate 1996 29:371).
Techniques have recently emerged for the in vitro propagation of large numbers of DC from circulating monocytes or from CD34 hematopoietic progenitors in response to granulocyte-macrophage colony stimulating factor (GM-CSF) in combination with either interleukin 4 (IL-4) or tissue necrosis factor α (TNFα) (Sallusto et al., 1994, J. Exp. Med. 179:1109–1118; Romani et al., 1994, J. Exp. Med. 180:83–93: Caux et al., 1992, Nature 360:258). The combination of GM-CSF and IL-4 induces peripheral blood monocytes to differentiate into potent DC (Kiertscher and Roth, 1996, J. Leukocyte Biol. 59:208–281). With the combination of these two cytokines a 100-fold increase in the yield of DC can be achieved from peripheral blood in vitro.
In mice, tumor antigen-loaded in vitro generated DC have been shown, by various groups, to prevent the development of tumors and more importantly to induce the regression of established tumors. A clinical trial has been conducted in which patients with melanoma are being treated with GM-CSF-activated APC pulsed with a peptide from the MAGE-1 tumor antigen (Mehta-Damani, et al., 1994, J. Immunology 153:996–1003). Pre-immunization, tumor-infiltrating lymphocytes from two patients were predominantly CD4+ and lacked specific tumor reactivity. In contrast, after immunization tumor infiltrating lymphocytes from the same patients were predominantly CD8+ and demonstrated MAGE-1 specific anti-tumor cytotoxicity. It thus appears from these studies that DC have a unique and potent capacity to stimulate immune responses.
Dendritic cell therapy thus represents a very promising approach to the treatment of disease, in particular, cancer. There is a continuing need for improved materials and methods that can be used not only to expand and activate antigen presenting dendritic cells, but to facilitate the migration of DC so as to be both therapeutically as well as prophylactically useful.

Chemokines as adjuvants of immune response


A contact hole is formed in a protective film 9 so as to communicate with an upper electrode 15. In the contact hole is formed a conductor 13 made of substantially the same material as used for the upper electrode 15, so as to communicate with the upper electrode 15 and extend to the outside of the contact hole. The conductor 13 is electrically connected to a memory cell transistor, by a wiring layer 14.

1. Field of the Invention
The present invention relates to a ferroelectric memory, an more particularly to a ferroelectric memory having a memory cell transistor and a ferroelectric capacitor both formed on a semiconductor substrate for memory retention.
2. Description of the Related Art
In recent years, active technical developments have been made on a ferroelectric memory having a ferroelectric film of spontaneous polarization property as the capacitive insulating film. This ferroelectric memory has a feature of being capable of storing information by the polarization of the ferroelectric capacitor formed on a semiconductor substrate. FIG. 4 shows a sectional view of an example of the unit cell memory constituting a conventional ferroelectric memory. As shown in FIG. 4, n.sup.+ diffusion layers 8 as source/drain regions are formed in the surface regions of a p type silicon substrate 1, and also a gate electrode 7 is formed on the p type silicon substrate via a gate insulating film; thereby, a field effect transistor (which is a cell transistor) is constituted. A bit line 10 made of Al is connected to one of the diffusion layers 8 as source/drain regions, of the field effect transistor.
On the field effect transistor is formed, via an interconnection insulating film, a ferroelectric capacitor constituted by a lower electrode 3, a ferroelectric film 4 and an upper electrode 5. The upper electrode 5 is connected to the other diffusion layer 8 as source/drain region, of the field effect transistor via a wiring layer 6. The ferroelectric film 4 is made of PZT (PbZr.sub.x Ti.sub.1-x O.sub.3), SBT (SrBi.sub.2 Ta.sub.2 O.sub.9) or the like. The lower electrode and the upper electrode are made of an oxidation-resistant noble metal (e.g. Pt) or a conductive oxide (e.g. RuO.sub.2) because annealing in an oxidizing atmosphere is often necessary for the formed ferroelectric capacitor in order to stabilize the thin ferroelectric film of the capacitor. As the wiring layer 6, there is used, for example, a multilayered film consisting of a Ti layer, a TiN layer and an Al layer because the wiring layer 6 are required to be superior in fine processability, adhesivity to Si or SiO.sub.2 and resistivity (i.e. low resistivity).
An equivalent circuit of this memory cell is shown in FIG. 5. A memory cell MC is constituted by the in-series connection of a field effect transistor Tr and a ferroelectric capacitor Cf. The gate electrode of the field effect transistor Tr is connected to a word line WL; one of the source/drain regions is connected to a bit line BL; and the other source/drain region is connected to one of the electrodes of the ferroelectric capacitor Cf. The other electrode of the ferroelectric capacitor Cf is connected to a plate line PL. Generally, the word line WL functions also as the gate electrode of the field effect transistor Tr, and the plate line PL functions also as the lower electrode of the ferroelectric capacitor.
The memory cell MC shown in FIG. 5 is arranged in a matrix form and constitutes a large-scale non-volatile memory.
Next, the process for producing a conventional memory cell shown in FIG. 4 is explained with reference to FIG. 6. FIGS. 6(a) to 6(c) are sectional views showing the steps of the process for producing a conventional memory cell. A ferroelectric capacitor comprising a lower electrode 3, a ferroelectric film 4 and an upper electrode 5 is formed on an interconnection insulating film formed on a silicon substrate 1 having a semiconductor integrated circuit (e.g. memory cell transistors) embedded therein; and a protective film 9 is formed thereon [FIG. 6(a)]. As shown in FIG. 6(b), contact holes are formed which communicate with the upper electrode of the capacitor and also with the diffusion layers of the field effect transistor. Then, as shown in FIG. 6(c), wiring layers are formed to connect one of the diffusion layers of the field effect transistor to the upper electrode of the capacitor and also to form a bit line. Thereafter, a heat treatment is conducted at a temperature higher than 300.degree. C. This heat treatment is an essential step for reduction in contact resistance of transistor, stabilization of threshold volatage, removal of damage applied to ferroelectric capacitor during LSI production process, etc.
In the conventional memory cell, however, there has been a problem that the above heat treatment incurs a substantial reduction in residual polarization intensity of ferroelectric capacitor, which leads to significant deterioration of the memory retention and data-rewriting life of non-volatile memory. The reason for the problem is that the substance (e.g. titanium) constituting the wiring layer diffuses through the upper electrode along the grain boundaries, reaches the ferroelectric film and reacts chemically with the film.
The same problem appears also when a protective film is formed on a memory cell having a structure shown in FIG. 4. That is, at the time when a silicon nitride (Si.sub.3 N.sub.4) film is formed according to a conventional method (e.g. plasma CVD at a substrate temperature of about 300 to 400.degree. C.), the ferroelectric capacitor is deteriorated and the resulting ferroelectric memory has very low reliability.


The present invention is directed to resins made from cashew nutshell liquid and vinyl hydrocarbons and processes for manufacturing the resins. These resins exhibit lower viscosity than the phenol-based homologs. They also exhibit good compatibility with a wide range of solvents, mineral and natural oils, epoxy curing agents, liquid epoxy resins, and polymers, which make them suitable additives as non-reactive diluents for solvent-free coating formulations; tackifiers for structural adhesive, pressure sensitive and hot-melt adhesives; stabilizers for lubricants, fuel and polymer formulations; plasticizers for thermoplastic polymers and processing aid for rubber compounding and stabilizers for respective rubber artifacts. These resins are also valuable precursors for the manufacture of epoxy resins and polyols for coating, adhesive and composite formulations exhibiting ameliorated performance in water repellency, anti-corrosion, and fast hardness development during cure.

Phenol-modified hydrocarbon resins are widely used in coatings and adhesive formulations, and also widely used in the manufacturing of rubber products. These resins improve the compatibility of the ingredients in such formulations. In addition, the resins provide improved chemical and weathering resistance to finished products designed to perform under harsh environmental conditions, such as wide variation of temperature, oxidation by air, and light exposure. Other advantages include the substantial improvement of the adhesive properties in coating and adhesive formulations.
Phenol-modified hydrocarbon resins encompass a wide range of products produced by the reaction between phenols and vinyl aliphatic and aromatic monomers. In general, the composition of these resins is quite complex, which can be simply characterized by a mixture of monomeric and polymeric components bearing distinct chemical functionalities. For instance, the reaction of unsubstituted phenol with vinyl hydrocarbon monomers, such as styrene, alpha-methylstyrene, vinyltoluene, indene, coumarone, or any other similar vinyl monomers, or a mixture thereof, catalyzed by strong acids, produces liquid to wax-like resins containing variable amounts of short polymers of vinyl monomers, in addition to the alkylated phenol components. The polymer fraction is mostly composed of cyclic dimers and trimers of the vinyl monomers, with small amounts of respective linear oligomers. The alkylated phenol fraction is also multicomponent, as it contains variable amounts of monosubstituted, disubstituted, and trisubsituted phenolic compounds. The compositions of these resins can be controlled by careful adjustments of the reaction conditions. However, the most significant factor to control the desired physico-chemical properties is the judicial selection of structural variations on the phenol and on the vinyl hydrocarbon monomer building blocks. Mixtures of phenols and/or vinyl monomers are very often employed to achieve the right balance of polarity, solubility, and fluidity, which is intimately related to the hydroxyl functionality, the content of aromatic, hydrophobic moieties, and polymer fractions, in addition to the molecular weight distribution. For this purpose, it is a common practice to incorporate small portions of an alkyl-substituted phenol to the reaction mixture. The most commonly used alkyl-substituted phenols are ortho- and para-tert-butylphenol, octylphenol, and nonylphenol. These phenols can be produced in-situ, prior to or after the reaction with the intended vinyl monomers. These variations in the process can add cost and complexity to the manufacturing of such resins. In addition, it can be more difficult to stabilize the process and minimize the variability between batches as the number of steps and raw materials are increased.
Cashew nutshell liquid (CNSL) contains a large concentration of cardanol and cardols, a natural source of meta-substituted alkylated phenols and resorcinols. CNSL is relatively low cost, and it is a globally available bio-renewable commodity, which makes it an ideal building block for the manufacturing of phenol-modified hydrocarbons resins. Due to the structure of the components of CNSL, the hydrocarbon resins can be manufactured with fewer steps and/or raw materials.
Among the advantages of cardanol-based hydrocarbon resins are low viscosity, improved solubility with organic solvents, very low cloud points, and compatibility with a great number of resins and polymer formulations.

CNSL-based hydrocarbon resins, preparation and uses thereof


A method includes etching a dummy gate to form an opening. A gate dielectric layer is deposited in the opening. A blocking layer is deposited over the gate dielectric layer, wherein the blocking layer has a bottom portion over a bottom of the opening and a sidewall portion over a sidewall of the opening. An adhesive layer is deposited over the bottom portion of the blocking layer. A metal layer is deposited over the adhesive layer, wherein the metal layer is in contact with the sidewall portion of the blocking layer.

The continuous effort to improve semiconductor device performance brings with it a continuous effort of scaling down device feature sizes thereby improving the device performance speed and its functional capability. In the course of semiconductor integrated circuit (IC) evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. Such scaling down has also increased the complexity of IC processing and manufacturing.

Method for manufacturing semiconductor device

TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD.


A data processing system (10) capable of generating an output waveform (22) that has enhanced pulse width resolution. In one form, the system uses a counter (34) which is incremented by an input clock (20) running at an operating frequency of the system. Instead of incrementing the counter (34) by one, the counter (34) is incremented by a power of two so that the counter (34) appears to be counting a power of two faster. However, in order to increase the effective resolution of the counter (34), the second edge of the output waveform (22) must be correctly adjusted depending on the desired duty cycle and period. The end result is a counter (34) that can produce a power of two greater resolution while still using the operating frequency of the system as an input clock (20).

Microcomputers today are used to control a wide variety of products ranging from a simple household appliance to a complex automobile. One of the important uses carried out by the microcomputer is timing control. Timing control can also range from the very simple to the very complex. A household appliance may only require a microcomputer timer to count how much time has elapsed between two events in order to control the appliance. An automobile, on the other hand, may require the timer to generate or recognize complex waveforms in order to control the automobile engine.
An important use for timer functions, other than control, is the generation of clocks for communication systems. Communication systems transfer data between multiple locations. Some communication systems require one or more clocks in order to determine when the various bits of data are to be sent. A timer is a convenient device which can be used to generate the clocks required by a communication system. A timer can also be used to generate a wide range of output waveforms that can be used for purposes other than control and the clocking of communication information.
In order to discuss timers, it is necessary to define the basic terminology of a waveform, such as period, cycle, frequency, pulse width, and duty cycle. Period and cycle are being used synonymously in this document. The period or cycle of a waveform is the length of time between any two rising edges or any two falling edges of the waveform. The frequency of a waveform is the inverse of the period, that is frequency=1/period. As the period increases, the frequency decreases. Therefore, a waveform with a long period has a low frequency.
The pulse width of a waveform is the length of time that the pulse remains in a predetermined state, either high or low. The duty cycle of a waveform is the percentage of time that the waveform is high during the total waveform period. For example, a waveform that has a 70% duty cycle is high for 70% of the total period and low for the remaining 30% of the period. A waveform that has a 50% duty cycle is high for 50% of the total period and low for the remaining 50% of the period. And a waveform with a 20% duty cycle is high for 20% of the total period and low for the remaining 80% of the period.
Many timers operate by using an input clock, a counter, and some type of compare logic. The counter is used to keep track of the length of time that has elapsed from an initial starting time. The counter is incremented by the first edge of the input clock. On the second edge of the input clock, the contents of the counter are compared to a preprogrammed value to determine if the two values match. If a match occurs, the timer has determined that a sufficient length of time has elapsed since the initial starting time. The timer then performs the appropriate function, such as causing an interrupt or driving a value on an output pin. If a match does not occur, the timer has determined that a sufficient time has not elapsed since the initial starting time and the counter is again incremented on the next edge of the input clock.
Because the counter value changes after each increment, the compare operation must be performed after each increment of the counter. If a compare is not performed after each increment, a match may occur and yet go undetected. There are only two edges during each period of the input clock. The first edge is used to increment the counter and the second edge is used to trigger the compare operation. As a result, the counter can only be incremented once during each period of the input clock. Thus the effective rate at which the counter can count is limited by the frequency of the input clock. A standard counter with an input clock frequency of "F" can only count at the rate of "F". For example, a counter with an input clock of 6 megahertz can only count at the rate of 6 megahertz.
The rate at which a counter can count determines the resolution of the timer. The resolution of existing timers is limited by the frequency of the input clock. Many microcomputer customers want timers that have greater resolution. And unfortunately, the easy solution of merely increasing the frequency of the input clock in order to increase the resolution of the timer is usually not a viable option. The input clock to the timer is usually the fastest system clock operating throughout the entire microcomputer. Increasing the speed of this system clock affects all parts of the system, not just the timer. Some circuitry within the microcomputer will not operate correctly above a certain maximum frequency, and this maximum frequency may not be great enough to produce the required resolution in the timer.

Data processing system which generates a waveform with improved pulse width resolution