A method and apparatus for maintaining relatively low ripple current in a dc-dc converter while minimizing the size of an inductive line filter utilizes a transformer having at least a pair of secondary windings in which the secondary windings are selected to have different numbers of winding turns depending on the specific design of the ideal duty factor at which the converter will be operated. In addition, the converter is provided with an active pre-load which establishes a continuous conduction current when load current is below some selected minimum value in order to provide control stability during light load conditions without converter oscillations. In an illustrated embodiment, the active pre-load circuit comprises a resistor connected in series with a transistor across the voltage output of the converter with the gate terminal of the transistor connected through a zener diode to the control circuit so that when the control voltage feedback signal drops to a selected low value, the transistor is biased into conduction to connect the resistor as a load to maintain a minimum load current. Alternatively, the transistor can be connected across one of the diodes in the transformer secondary and arranged so as to conduct current in a direction opposite to the direction of current through the diode so that under low current conditions, a current loop is formed through the transformer to maintain continuous current flow and allow the converter to operate at very light loads.

This invention relates to dc-dc power converters and, more particularly, to half-bridge, pulse-width modulated dc-to-dc converters.
The conventional half-bridge (HB) pulse-width modulated (PWM) converter is well known and is frequently used for low-to-medium dc-dc power conversion applications. An exemplary form of such converter is shown in FIG. 1 at 10. Normally, the two power switches S1 and S2 in the HB PWM converter are switched alternately with symmetrical duty cycle control and operate with hard switching. The electronic power switches S1 and S2 may be MOSFET or other well known types of electronically controllable, high speed switches and are serially connected across a source 12 of dc power (battery or rectifier coupled to ac source). A junction intermediate the switches S1, S2 is connected to one terminal of primary winding N.sub.p of a power transformer TR through a series capacitor Cb. Transformer TR has a pair of substantially identical windings NS, and NS.sub.2 having a common terminal at 14 connected to a relatively negative dc output terminal 16. Opposite winding end terminals 18 and 20 are connected through respective diode rectifiers D1 and D2 to one end of an output filter inductor Lf. Another end of inductor Lf connects to a relatively positive output terminal 22. A resistive load R.sub.0 and output filter capacitor C.sub.0 connect in parallel to the dc output terminals. The converter 10 operates by gating switch S1 into conduction for a controlled time interval, gating switch S1 out of conduction and then gating switch S2 into conduction. Power is transferred into the converter while S1 conducts. During S2 conduction, the reactive components allow resonant action to occur so that current continues to the load. Due to the high switching loss and high switching noise problems associated with hard-switching operation of the devices S1, S2, the conventional HB PWM converter is not suited for high-frequency operation. In order to reduce the switching loss and noise of the converter, several zero voltage switching (ZVS) techniques have been developed.
Tabisz, Lee, and Jovanovic in U.S. Pat. No. 4,860,184 "Half-Bridge Zero-Voltage Switched Multi-Resonant Converter," disclose a HB converter which can achieve ZVS for both the primary switches (S1, S2) and the secondary rectifying diodes (D1, D2), but it requires the use of a large resonant inductor which results in very high circulating energy and low efficiency. Also, the converter relies on wide-range frequency modulation to regulate the output voltage.
Farrington, Jovanovic, and Lee in U.S. Pat. No. 5,325,283 "Novel Zero-Voltage-Switching Family of Isolated Converters," show a HB converter using symmetrical duty cycle and variable frequency control to achieve ZVS and regulate output voltage. The need for wide-range switching frequency modulation significantly penalizes the performance of the converter by increasing the size of the reactive components (capacitors, transformers, and inductors). In addition, the converter requires a large output filter inductor and also a third rectifying diode.
Ninomiya, Matsumoto, Nakahara and Harada ("Ninomiya") in their 1991 IEEE PESC Record article "Static and Dynamic Analysis of ZVS Half-Bridge Converter with PWM Control" disclose a HB converter using magnetizing energy and asymmetrical duty cycle to achieve ZVS. Its major limitation is in requiring the use of a large output filter inductor when it operates at low duty cycles. This significantly increases the size of the converter and also results in a decrease in conversion efficiency. In addition, this converter exhibits an inherent control stability problem at light load which necessitates the use of a large pre-load for very light load or no load operation.
Imbertson in U.S. Pat. No. 5,245,520 "Asymmetrical Duty Cycle Power Converter" discloses a HB converter which uses asymmetrical duty cycle control and a commutating inductor in series with the power transformer to achieve ZVS. Similar to the Ninomiya converter, Imbertson also requires the use of a large output filter inductor when operating at low duty cycles and exhibits an inherent control stability problem at light load. With the help of a series commutating inductor, the switch conduction loss is somewhat reduced, but ZVS can be easily lost as load current decreases.
FIGS. 2A and 2B show the circuit schematic and switching waveforms respectively of the ZVS HB converter disclosed in the Ninomiya article. Two primary switches S1 and S2 are turned on and off complementary with certain dead times (t0-t1 and t2-t3) in between to allow ZVS to occur. The power transformer TR has one primary winding N.sub.P and two identical secondary windings NS1 and NS2. The transformer is designed to have a fairly low magnetizing inductance so that the peak magnetizing current at either switch S1 or S2 turn-off is greater than the reflected output filter inductor Lf current. In this way, ZVS operation can be maintained even at light load. During the S1 OFF period (t1-t2) and ON period (t3-t0'), the voltage, V.sub.B, appearing in front of the output filter inductor L.sub.f is equal to DV.sub.in /(Np/Ns) and (1-D)V.sub.in /(Np/Ns), respectively, where D is the duty cycle of switch S1 in percent on-time and NP and NS are the number of turns in the primary and each secondary winding, respectively. Obviously, when D is close to 50%, V.sub.B is close to the output voltage (Vo) during both S1 OFF and ON periods, and consequently, only a very small output filter inductor (L.sub.f) is needed. Unfortunately, there are several reasons why the converter can not operate at close to 50% duty cycle at nominal input voltage in most applications. The Ninomiya HB converter shown in FIG. 2A has a voltage conversion-ratio characteristic as shown in FIG. 3. It can be seen that the converter has a maximum gain at 50% duty cycle. In order to accommodate certain load or line transient response requirements as well as component tolerances, the converter is typically operated at around 35% duty cycle even if the steady-state input voltage V.sub.IN is fixed. Considering that in most applications the input voltage has a certain variation range, the steady-state duty cycle is often less than 30%. With such a low duty cycle, V.sub.B will be much high than Vo during S1 ON period and much lower than Vo during S1 OFF period. As a result, the converter requires the use of a large L.sub.f to meet adequate efficiency and filtering requirement. This significantly increases the size and cost of the converter and also results in higher power losses.
Another drawback of the Ninomiya converter shown in FIG. 2A is that it has an inherent control stability problem at very light load or no load. As a result, the converter requires the use of either a pre-load resistor which is simple but very lossy or an active pre-load which is very complicated and expensive to implement.
This invention discloses an improved HB converter that overcomes the above-mentioned drawbacks of the prior art HB converters.

Half-bridge DC to DC converter with low output current ripple


A holographic optical accessing system includes a light source for emitting a light beam; an optical assembly module for receiving the light beam and generating a signal beam and a reference beam that are parallel to each other rather than overlap with each other, and have the same first polarization state; a lens module for focusing the signal beam and the reference beam on a focal point at the same time; and a storage medium for recording the focal point. The optical assembly module includes at least a data plane for displaying image information so that the signal beam contains the image information.

The optical accessing system has been widely used for data reading and data recording in present. However, because of the material characteristics of the storage medium within the optical accessing system and the accuracy of accessing method applied in the optical accessing system, the capacity of data can be recorded in an optical disc by a conventional optical disc accessing technology is limited. Therefore, an optical holography technology (or holographic data storage technology) is developed for raising the recording density on an optical disc.
FIG. 1 depicts a diagram of a holographic optical accessing system 100, wherein the holographic optical accessing system 100 includes: a signal beam 12, a data plane 14, a reference beam 16, a storage medium 18, a data beam 22, and a detecting apparatus 20.
When the data recording is processed in the holographic optical accessing system 100, a light beam, e.g. a laser beam emitted from a laser, is split into two light beams by a beam splitter (not shown), wherein one of the two light beams is regarded as the signal beam 12 after the light beam is emitted to the data plane 14, because the image information presented on the data plane 14 is also contained in the signal beam 12; another light beam split from the laser beam is regarded as the reference beam 16.
During the process of data recording, the signal beam 12 and the reference beam 16 are both focused on a focus point 24 of the storage medium 18 at the same time, wherein the storage medium 18 can be a photosensitive interface, such as photopolymer. When the signal beam 12 and the reference beam 16 are both focused on the focal point at the same time, the interference stripes are formed on the focus point 24, so as the image information which is contained in the signal beam 12 is recorded on the focal point 24 as a grating, and the data recording process is completed.
During the process of data reading in the holographic optical accessing system 100, only the reference beam 16 is focused on the focus point 24. After the reference beam 16 is focused on the focal point 24, a data beam 22 is then generated and propagates through the rail of the signal beam 12. The data, recorded on the focal point 24, is read out, so as the image information originally stored on the data plane 14 is also contained in the data beam 22. When the data beam 22 is received by the detecting apparatus 20 placed on the path of the data beam 22, the image information originally written on the data plane 14 will be projected on the detecting apparatus 20 and the data reading process is completed.
In addition, the data plane 14 is a SLM (Spatial Light Modulator), and the SLM can be a DMD (Digital Micro-mirror Device), a LCD (Liquid Crystal Display), or a LCOS (Liquid Crystal on Silicon), wherein the DMD, LCD, or LCOS are all composed by a plurality of displaying units arranged as an array, and image information can be presented by these displaying units with light states or dark states. The detecting apparatus 20 can be a CMOS (Complementary Metal-Oxide Semiconductor) or a CCD (Charge Coupled Device).
In the holographic optical accessing system 100, data is recorded in the storage medium 18 via the signal beam 12 and the reference beam 16 focused on the focal point 24 at the same time, wherein the signal beam 12 and the reference beam 16 are on-axis with each other. FIG. 2 illustrates the signal beam 12 and the reference beam 16 processing a data recording in the conventional holographic optical accessing system 100, wherein the signal beam 12 and the reference beam 16 have the same optical axis 15 and is so called on-axis. That means both the signal beam 12 and the reference beam 16 are contained in a light beam. As depicted in FIG. 2, when the signal beam 12 and the reference beam 16 are focused on the focal point 24 of the storage medium 18 at the same time via the lens module 19, the interference stripes are formed on the focal point 24, so as the data recording process is completed. However, because the signal beam 12 and the reference beam 16 are both further reflected back from the storage medium 18 to the lens module 19 via the same optical path, a crosstalk interference could be introduced by a conjugate light of the signal beam 12 and the conjugate light of the reference beam 16, so as the data recording accuracy is affected. Therefore, providing a holographic optical accessing system for fixing the above-described problem is the purpose of the present invention.


A multioctave microstrip antenna for mounting to one side of a ground plane and including a metal foil spiral-mode antenna element and a dielectric substrate positioned between the antenna element and the ground plane. The spiral-mode antenna element has a frequency-independent pattern formed therein, such as a sinuous, log-periodic, tooth, or spiral pattern. The antenna can be mounted substantially flushly to the surface of a structure without perforating the surface of the structure and can be conformed thereto. The antenna exhibits a broad bandwidth, typically on the order of 600%.

In many antenna applications, for example such as for use with military aircraft and vehicles, an antenna with a broad bandwidth is required. For such applications, the so-called "frequency-independent antenna" ("FI antenna") commonly has been employed. See for example, V. H. Rumsey, Frequency Independent Antennas, Academic Press, New York, N.Y., 1966. Such frequency-independent antennas typically have a radiating, or driven element with spiral, or log-periodic geometry that enables the FI antenna to transmit and receive signals over a wide band of frequencies, typically on the order of a 9:1 ratio or more (a bandwidth of 900%). European Patent Application No. 86301175.5 of R. H. DuHamel entitled "Dual Polarized Sinuous Antennas", published Oct. 22, 1986, publication No. 0198578, discloses frequency-independent antennas with sinuous structures.
In a frequency-independent antenna, a lossy cylindrical cavity is positioned to one side of the antenna element so that when transmitting, energy effectively is radiated outwardly from the antenna only from one side of the antenna element (the energy radiating from the other side of the antenna element being dissipated in the cavity). However, high-performance military aircraft, and other applications as well, require that the antenna be mounted substantially flush with its exterior surface, in this case the skin of the aircraft. This undesirably requires that the cavity portion of the FI antenna be mounted within the structure of the aircraft, necessitating that a substantial hole be formed therein to accommodate the cylindrical cavity, which typically is two inches deep and several inches in diameter for microwave frequencies. Also, the use of a lossy cavity to dissipate radiation causes half of the radiated power to be lost, requiring a greater power input to effect a given level of power radiated outwardly from the FI antenna.
In recent years the so-called "microstrip antenna" has been developed. See for example, U.S. Pat. No. 29,911 of Munson (a reissue of U.S. Pat. No. 3,921,177) and U.S. Pat. No. 29,296 of Krutsinoer, et al (a reissue of U.S. Pat. No. 3,810,183). In a typical microstrip antenna, a solid thin metal patch is placed adjacent to a ground plane and spaced a small distance therefrom by a dielectric spacer. Microstrip antennas have generally suffered from having a narrow useful bandwidth, typically less than 10%. At least one researcher has made preliminary investigations into using a single microstrip line wound as an Archimedean spiral (C. Wood, "Curved Microstrip Lines as Compact Wideband Circularly Polarized Antennas", published in Inst. Elec. Eng. Microwaves, Optics and Acoustics, Vol. 3, pp. 5-13, January 1979). That researcher concluded, however, that the achievement of a microstrip-type antenna with a wide bandwidth analogous to the conventional spiral (of a frequency-independent antenna) was not feasible because the radiation patterns of the contemplated low-profile antenna tend to exhibit a large axial ratio.
Accordingly, it can be seen that a need yet remains for an antenna which has the dimensional characteristics of a microstrip antenna, i.e., has a low-profile, and has a broad bandwidth similar to a frequency-independent antenna. It is to the provision of such an antenna, therefore, that the present invention is primarily directed.


The present invention relates to a sensor for verifying that a motor has stopped rotating including rotation due to inertia.. Respective signal input lines are connected to three power supply lines of a three phase AC motor. A high frequency signal current is supplied to one of the power supply lines, and the difference in the current flowing in the other two power supply lines is sampled from the signal input lines connected to the two power supply lines, and made an output from a sensor section. The sensor output is subjected to a threshold value operation in a signal processing circuit, and the resultant threshold operation output is output from an on-delay circuit as a motor rotation presence judgment output.

As a sensor for verifying that a motor has stopped rotating, there is, for example one, which uses an electromagnetic pickup (refer to PCT Publication No. WO94/23303 (PCT/JP93/00411)).
With this device, a metal disc having a plurality of metallic protrusions located at even spacing around the surface periphery thereof is secured to a motor rotation shaft, and an electromagnetic pick up, serving as a sensor head, is provided at a location facing the protrusions at a predetermined distance therefrom. When the metal disc rotates with rotation of the motor, fluctuations are produced in a magnetic flux with the passing of the respective protrusion. By subjecting the resultant fluctuations in the output from the electromagnetic pick up, due to these magnetic flux fluctuations, to threshold value processing or the like, using a signal processing circuit, then during rotation of the motor (including rotation under inertia), an output of logic value 0 showing that the motor is rotating (danger side) is produced from the signal processing circuit, while when the motor rotation has practically stopped (safe side), an output of logic value 1 is produced from the signal processing circuit.
However, in devices which use an electromagnetic pickup for the sensor head, the spacing between the protrusions and the electromagnetic pick up is extremely small. Moreover, this spacing must be controlled very accurately. Therefore, the sensor head attachment operation becomes difficult. Furthermore, there is a problem in that the fitted location of the pickup head and related parts must be periodically checked, thus increasing maintenance and inspection costs.
Moreover, the circuit configuration for prohibiting generation of a motor stopped judgment output, for the period including from after shutting off the motor power source until motor rotation under inertia has reduced to a sufficiently slow speed is complicated.
The present invention takes into consideration the abovementioned situation, with the object of providing a motor stopped verification sensor which does not have an electromagnetic pickup type sensor head, thus obviating the need for control of the attachment position, and hence the attachment operation is extremely simple.


A display apparatus includes a transparent display device with a first region displaying images, a second region transmitting external light, the first and second regions being adjacent to each other and alternating in a first direction, a first polarizer on an optical path emitted by the transparent display device and configured to linearly polarize the external light, a first retarder between the first polarizer and the transparent display device to delay a phase of the external light, a second polarizer on the transparent display device to linearly polarize the external light, and a pattern retarder between the second polarizer and the transparent display device, the pattern retarder including a second retarder to delay a wavelength of the external light by a first phase and a third retarder to delay the wavelength by a second phase, the second and third retarders being alternately arranged in the first direction.

1. Field
Example embodiments relate to a display apparatus, and more particularly, to a display apparatus that changes light transmittance according to modes.
2. Description of the Related Art
Since an organic light-emitting display apparatus has excellent characteristics in terms of viewing angles, contrast, response speeds, and power consumption, an application range of the organic light-emitting display apparatus has been increased from a personal portable device, e.g., a MP3 player or a mobile phone, to a TV. Such an organic light-emitting display device has a self-emission characteristic and does not require a separate light source, e.g., unlike a liquid crystal display device. Thus, thickness and weight of the organic light-emitting display device may be decreased. Also, the organic light-emitting display device may be configured as a transparent display device by forming a transparent thin film transistor or a transparent organic light-emitting diode therein and forming a transmissive region (transmissive window) separately from a pixel region.

Display apparatus capable of controlling light transmittance


A computer-implemented method and system that operates on a server includes a time and expense management interface for obtaining crew specific information for crews maintaining a utility distribution system. The server is coupled to a wireless communication infrastructure for receiving crew specific information. A portable electronic device receives a selection of a crew with members. The portable electronic device receives the identifier of the at least one or more members of the crew. Once verified, the portable device receives time entries and expense entries, for the at least one or more members of the crew. Business rules are applied to the time entries and expense entries. Once the business rules are satisfied, the time entries and expense entries are stored on the portable electronic device. When the portable electronic device is in proximity to the wireless communication infrastructure, the crew specific information is transmitted to server.

Organizations that maintain and operate various utility distribution systems, such as, electrical power distribution and/or transmission systems, cellular, telecommunications, cable TV, water and sewer, natural gas and others, are generally responsible for maintaining and operating a large number of devices or objects that are distributed across a large geographic area. In order to repair distribution systems organizations will hire private contractors and other utility operators to help with installing, repairing, and restoring distribution systems. This is especially true after large disruptive events, such as, winter storms, hurricanes, tornadoes, floods, fires, and earthquakes. Keeping track of repair teams is often done by paper and pencil because cellular and other service may not operate reliably, particularly when electric power distribution system is down. Addressing issues with particular components, parts, and sub-systems and maintaining the operations of utility systems is a challenge. It can also be a challenge when documenting time and expense for government agencies, such as public utility commissions.


A superconductive device manufacturing method is disclosed, which can prevent the characteristic deterioration on the processed surface, reduce the number of process steps, and thereby shorten the manufacturing time. The superconductive device manufacturing method comprises the steps of: forming a YBCO film (301) on a substrate (201); forming a mask pattern (302) on the formed YBCO film (301); and etching the YBCO film (301) by use of the formed mask pattern (302) and a plasma including at least oxygen plasma.

1. Field of the Invention
The present invention relates to a superconductive device manufacturing method, and more specifically to a method of manufacturing a superconductive device by use of a plasma etching process.
2. Description of the Prior Art
As the etching method adopted to process a YBCO superconductive thin film of a superconductive device, various etching methods are so far well known, such as wet etching, laser etching, dry etching, focused ion beam etching, etc.
Here, a method of processing a YBCO superconductive thin film by use of dry etching is disclosed in Hiroshi Sato, Hiroshi Akoh, Keirou Nishimura, Masahiro Aoyagi and Susumu Takada; Journal of Japan Applied Physics Society, 31, (1992) L1044, for instance. In this processing method, as shown in FIG. 11, after Ar gas has been introduced into an ECR (electron cyclotron resonance) chamber 1101, an ECR plasma is generated by use of a microwave, and an Ar ion beam is extracted from the generated ECR plasma into an etching chamber 1102. Further, by use of the extracted Ar ion beam, the YBCO superconductive thin film formed on a sample 1104 held by a sample holder 1103 is etched. In this Paper, the acceleration voltage of the Ar ions is 240 V, and the ion current density is 0.15 mA/cm.sup.2. Further, as an etching mask, an ordinary photoresist is used.
Here, when the YBCO superconductive thin film is being etched, the temperature on the processed surface rises locally. Therefore, oxygen is inevitably desorbed from the processed surface, so that the superconductivity characteristics deteriorate. To overcome this problem, in this instrument as shown in FIG. 11, the sample 1104 is cooled by use of liquid nitrogen; that is, the sample temperature is reduced to 77 K during etching to suppress the desorption of oxygen.
FIG. 12 shows an evaluation result of the relationship between the sample temperature during etching and the superconductivity characteristics. In more detail, FIG. 12 shows the relationship between a line width W (.mu.m) (on the abscissa) obtained by patterning the YBCO superconductive thin film into a line shape and the critical current density Jc (A/cm.sup.2) (on the ordinate), in which circular marks denote the values obtained when the sample 1104 is cooled down to 77 K by liquid nitrogen, and triangular marks denote the values obtained when the sample is cooled to 5.degree. C. by water. FIG. 12 indicates that the superconductivity characteristics are excellent when the sample 1104 is cooled down to 77 K by liquid nitrogen, as compared with when cooled to 5.degree. C. by water.
Further, another method of processing the YBCO superconductive thin film by use of dry etching is disclosed in Roland Barth, Bernd Spangenberg, Christian Jaekel, Hartmut G, Roskos, and Heinrich Kurz; Applied. Physics. Lett. 63, (1993) 1149, for instance. In this processing method, first a PMMA film is patterned by use of EBL (electron beam lithography); secondly a Ti film is patterned by RIE (reactive ion etching) with this PMMA film as a pattern mask; and the YBCO superconductive thin film is etched by sputtering Ar and oxygen ions with this Ti film as a mask (the acceleration voltage is 420 V and the sample temperature is 77 K). Further, after etching, the thin film is plasma-oxidized by use of an oxygen plasma, to restore oxygen desorbed from the processed surface during etching.
FIG. 13 is a graphical representation showing the comparison results of the superconductivity characteristics between before plasma oxidization and after plasma oxidization with respect to the line widths W of the YBCO superconductive thin film bridge (length: 10 .mu.m). FIG. 13 indicates that when the plasma oxidization is made, the superconductivity characteristics of the bridge with a line width of 0.4 .mu.m can be increased by about one order of magnitude, as compared with omission of plasma oxidization.
On the other hand, in the case where the superconductive device is a superconductive high frequency device, as the method of processing the YBCO superconductive thin film, an ion beam etching method using photolithography and a laser etching method are both so far well known.
The processing methods by use of these etchings are disclosed in Tsuyoshi Takenaka, Shuichi Fujino, Keiich Yamaguchi, Kunihiro Hayashi, and Katsumi Suzuki; Proceedings of 5th International Symposium on Superconductivity, Nov. 16-19, 1992, Kobe, Japan, for instance.
In this paper, after the YBCO superconductive thin film is formed on a MgO substrate with a thickness of 0.5 mm, this YBCO superconductive thin film is processed by etching, to manufacture a microstrip line resonator of 13.5 GHz. Further, this paper compares the characteristics of the resonator between when an ion beam etching using a photoresist is adopted and when a direct KrF excimer laser etching (without use of any photoresist) is adopted.
FIG. 14 is a graphical representation showing the relationship between the unloaded Q value of the resonator and the temperature obtained on the basis of the experiments, in which circular marks denote the values obtained when the ion beam etching method is adopted and cross marks denote the values obtained when the laser etching is adopted. FIG. 14 indicates that the dependency of the unloaded Q value upon the temperature is almost the same between the two cases. Therefore, this indicates that the laser etching method is advantageous to manufacture the superconductive high frequency device, because the photoresist process is not required.
As described above, when the YBCO superconductive thin film is etched, it is necessary to eliminate such a disadvantage that oxygen is desorbed from the etched surface due to a temperature rise, because the superconductivity characteristics deteriorate. Therefore, conventionally, in order to prevent oxygen from being desorbed from the etched surface, that is, to prevent the deterioration of the superconductivity characteristics, the sample is cooled by use of liquid nitrogen, or else oxygen is supplied to the etched surface by plasma oxidization after etching.
In the method of cooling the sample by use of liquid nitrogen, however, since the sample is cooled to 77 K by the liquid nitrogen and then heated to room temperature after etching, there exists a problem in that a long manufacturing time is inevitably needed.
Further, in the method of supplying oxygen onto the etched surface by plasma oxidization after etching, since an additional process is also required, there exists the similar problem in that the number of the manufacturing processes increases.
In addition, in these prior art methods, as understood with reference to FIGS. 12 and 13, although it is possible to prevent the deterioration of the superconductivity characteristics with respect to a wide pattern line formed by the etching, when the line having a width as narrow as several .mu.m or less is etched, the superconductivity deteriorates inevitably at an edge of the narrow line, so that a sufficient effect cannot be obtained.
In particular, in the case of the superconductive high frequency device, since the current is generally concentrated at the edge of the line, the quality of the line edge exerts a serious influence upon the device characteristics. Therefore, there exists a strong need of preventing oxygen desorption perfectly during etching process. For instance, in the above-mentioned Paper related to laser etching (Proceedings of 5th International Symposium on Superconductivity, Nov. 16-19, 1992, Kobe, Japan), it is disclosed that the melted YBCO with a width of 1 .mu.m and a height of 1 .mu.m is laminated on the line edge. In this case, it is apparent that the melted YBCO exerts a harmful influence upon the device characteristics.

Superconductive device manufacturing method

International Superconductivity Technology Center


A semiconductor device includes a heat generation element; a bonding member; first and second heat radiation plates disposed on first and second sides of the heat generation element through the bonding member; a heat radiation block disposed between the first heat radiation plate and the heat generation element through the bonding member; and a resin mold. The heat radiation block has a thickness in a range between 0.5 mm and 1.5 mm. The semiconductor device has high reliability of the bonding member.

A semiconductor chip having high withstand voltage and large current capacity generates large heat while operating. Therefore, it is required to improve heat radiation radiated from the chip. In view of the heat radiation, a semiconductor device having a large current semiconductor chip is disclosed in Japanese Patent Application Publication No. 2003-110064 (i.e., U.S. Patent Application Publication No. 2003-0022464-A1). The semiconductor device includes a pair of heat sinks made of metal, which are disposed on both sides of the semiconductor chip through a solder layer. Specifically, the heat sinks are bonded to the semiconductor chip with the solder layer. Thus, the heat generated in the chip is radiated from both sides of the chip through the heat sinks. Therefore, the heat radiation efficiency is improved. Here, the semiconductor device having the heat sinks is molded with resin. However, the outside surface of each heat sink is exposed from the resin mold so that the heat radiation efficiency becomes effectively.
In the above semiconductor device, each thermal expansion coefficient of the semiconductor chip, the heat sink and the resin mold is different each other. Therefore, a large heat stress is generated at each bonding portion between them. The large heat stress may crack the chip. To protect the chip, the thickness of the chip is thinned so that a distortion at the bonding portion between the chip and the solder layer becomes small.
However, in the above semiconductor device, dimensions and shape of the heat sink are not defined. Therefore, a strain in the solder layer disposed between the chip and the heat sink may be increased so that the bonding member cracks by the strain.

Semiconductor device having heat radiation plate and bonding member


Method and system are provided for the automated assembly of parts such as plastic parts into assemblies wherein assembly pallets loaded with their corresponding assemblies are stored and vertically indexed in an accumulator station to allow a previously applied material such as an adhesive to cure. Consequently, the system takes up little floor space. Entrance, dispensing and assembly stations, together with the accumulator station each has an enclosed chamber which is pressurized with an ambient at subatmospheric pressure in order to evacuate the enclosed chambers so that fumes from the adhesive utilized in securing the parts together are not allowed to escape at the stations during assembly of the parts.

The assembly of parts such as plastic parts which are adhesively secured together typically require a substantial amount of floor space in order that the adhesive has a sufficient amount of time to cure. Because of these space requirements, it is difficult to properly exhaust this area in order to prevent fumes from the adhesive from presenting an environmental hazard to workers in the area.
The Komatsu et al U.S. Pat. No. 4,789,417 discloses a windowpane mounting system including an adhesive application device for applying adhesive to a windowpane conveyed along a conveyor.
The Haba Jr. et al U.S. Pat. No. 4,815,190 discloses a method and system for the automated assembly of parts on an assembly pallet in an assembly area. The method and system utilize a robot system including a program-controlled robot.
U.S. Pat. No. 3,629,010 discloses a method and apparatus for sealing a cover to an assembled battery. The cover of the battery is coated with a sealant material by dispensing the sealant through nozzles which pivot into communication with the cover and reuniting the cover to the container and thereafter curing the sealant. A pallet is used to transport the battery.
The Edelberg et al U.S. Pat. No. 3,661,681 discloses an apparatus for assembling insole strips. A hot melted adhesive is supplied to the edges of the central strip or the corresponding inside edges of outer strips at a first adhesive station. The strips are then delivered to an assembly station where two adjacent strips are moved laterally into alignment with the edges of the central strip. The finished composite sheet is then delivered to a stacking station.
U.S. Pat. Nos. 4,458,628; 4,592,495; 4,635,827; 4,639,878; 4,666,732; 4,699,575; 4,724,302; 4,753,824; 4,834,824; 4,858,172; and 4,822,647 all disclose various automatic adhesive-applying devices and robots for moving the adhesive applying device along a variable program path.

Method and system for automated assembly of parts such as plastic parts


A pulse frequency modulator generates a pulse signal having a fixed duty ratio and a frequency which is adjusted such that a feedback voltage corresponding to the output voltage of a charge pump circuit is coincident with a predetermined first reference voltage. A driver, on receiving the pulse signal, turns on a first or second group of switches during the time periods corresponding to the high time periods of the pulse signal and turns on the other ones of the first and second group of switches during the time periods corresponding to the low time periods of the pulse signal.

1. Field of the Invention
The present invention relates to a charge pump circuit.
2. Description of the Related Art
Recent electronic apparatuses such as cellular phones and PDAs (Personal Digital Assistants) have incorporated devices which require driving voltages larger than battery voltages, such as LEDs (Light Emitting Diodes) used as back lights for liquid crystal displays. For example, these small-sized information terminals frequently employ Li-ion batteries which output voltages of about 3.5 V in general and output voltages of about 4.2 V even at fully-charged states, while LEDs require voltages larger than such battery voltages, as driving voltages therefor. In cases where a voltage larger than a battery voltage is required as described above, a charge pump circuit and a switching regulator are used for boosting the battery voltage for generating a voltage required for driving LEDs.
A charge pump circuit generates an output voltage by multiplying an input voltage by a predetermined voltage-boosting ratio. For example, in the case where the battery voltage is 3 V and the voltage-boosting ratio is 2, the output voltage is fixed to 6V. Accordingly, when a load circuit requires a driving voltage lower than 6V, there has been a need for inserting a power transistor in the input side or the output side of the charge pump circuit to constitute a linear regulator for adjusting the ON resistance thereof for adjusting the output voltage. For example, a relating technique is described in Japanese Patent Application (Laid Open) No. 2000-262043.
In the case of utilizing the technique described in Japanese Patent Application (Laid Open) No. 2000-262043, there is a need for using a power transistor, thereby increasing the number of components of the circuit and the area of the circuit.

Control circuit and control method for charge pump circuit


A hanging file folder to be used within a drawer that is lockable in position within the drawer. Therefore, movement is prevented of the hanging file folder during normal opening and closing movement of the drawer.

1) Field of the Invention
The field of this invention relates to a stationery product and more particularly to a hanging file folder that is used normally within a drawer with this hanging file folder to be used to store documents.
2) Description of the Prior Art
The use of hanging file folders within offices is exceedingly common. Typically, the hanging file folder is utilized within a drawer of a desk, a file cabinet or credenza. The drawer includes a pair of support rails located in a parallel evenly spaced apart arrangement. Between these rails, the hanging file folder is suspended. Each hanging file folder includes a pair of upper ends with the body of the hanging file folder assuming a V-formation. It is within the V-formation that one or more documents are to be contained for storage purposes. Within each upper end of the file folder is located a suspension bar. Each of these suspension bars terminate at their outer ends into hooks with these hooks in turn being supported on the rails. Normally, the file folders are to be readily movable on these rails.
Frequently the drawer is not completely filled with file folders. Therefore, during normal opening and closing movement of the drawer, the file folders tend to slide on the rails. Also, there is a tendency for the file folders to become skewed during opening and closing movement of the drawer. During the opening and closing movement of the drawer, not only do the file folders begin to slide together, compact and become skewed, the file folders can also become separated from their supporting rails. Generally this sliding movement of the file folders within the drawer is not desirable.


A self-drilling expansion screw capable of being driven by a screw driving means comprises: (a) a screw shank having a first end and a second end, including: (1) an expansion hole extending a distance along the axis of the screw shank from the first end toward the second end; (2) a slot located on the expansion hole, for communicating the expansion hole with the outer periphery of the screw shank; (3) a holding portion, formed by a plurality of strip grooves provided at the outer periphery of the screw shank with respect to the expansion hole; and (4) a screw threaded portion provided between the second end and the holding portion; (b) a nut member screwed from the screw threaded portion; (c) a taper head having a coarse end and a small end, the small end inserted into the expansion hole, the holding portion expanding outwards while the taper head is pushed into the expansion hole; (d) a drilling bit provided at the coarse end; and (e) a coupling portion provided at the second end of the screw shank, for engaging with a screw driving tool so as to drive the drilling bit to rotate around the axis of the screw shank. By the way, the self-drilling expansion screw is able to be used for drilling, fastening, or fixing.

Referring to FIG. 1 and FIG. 2, FIG. 1 is a front view of a conventional expansion screw, and FIG. 2 is a partial sectional view of the expansion screw shown in FIG. 1. The expansion screw shown in FIG. 1 and FIG. 2 comprises a screw shank 10, a nut member 20, and a taper head 30. The screw shank 10 having a first end and a second end includes: an expansion hole 14 shown in FIG. 2, which extends a distance along the axis of the screw shank 10 from the first end toward the second end; a slot 16 located on the expansion hole 14, for communicating the expansion hole 14 with the outer periphery of the screw shank 10; a holding portion 18, formed by a plurality of strip grooves 182 provided at the outer periphery of the screw shank 10 with respect to the expansion hole 14; and a screw threaded portion provided between the second end of the screw shank 10 and the holding portion 18, and having continuous threads around the outer periphery thereof. A nut member 20 is screwed onto the screw threaded portion. Additionally, the taper head 30 has a coarse end 302 and a small end 304, the small end 304 is inserted into the expansion hole 14. The holding portion 18 will expand outwards while the taper head 30 is pushed into the expansion hole 14.
In order to anchor the conventional expansion screw described hereinbefore in a concrete construction, rock, or stone, a hole which is fitted for the expansion screw has to be drilled first, and then it is inserted into the drilled hole, by the way of hitting or hammering. The taper head 30 is forced to urge against the expansion hole 14 and make the holding portion 18 be expanded. The conventional expansion screw thus can be anchored in the desired location. However, it is not always easy for a user to drill a hole with an optimum size for the expansion screw. Furthermore, a user has to drill a hole first, then insert the expansion screw and hit the end of the screw shank to anchor the expansion screw.

2nd. Fl., No. 10, 11th Alley, Lane 59, Mu-Cha Rd.


An adjustable height grow light for easy manual adjustment of the vertical position of the light fixture. The light includes a light stand having two vertical supports and a horizontal support connected to the vertical supports and defining an interior channel containing the operative elements of the light. Hanging from the vertical support is a light fixture adapted for holding at least one grow light. A ribbon torsion spring is secured within the interior channel of the horizontal support member on a ribbon spring axle. In series are first and second axles secured with the interior channel of the horizontal support, and first line and second lines are connected to the ribbon torsion spring at one end and to the light fixture at the other end. The first line is routed over the second axle and looped back to and over the first axle; the second line is routed over the second axle only. The ribbon torsion spring has a tension rating that permits easy manual positioning of the light fixture.

Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates generally to light fixtures, and more particularly to an adjustable height light fixture adaptable for use as a grow light.
2. Discussion of Related Art
The use of conventional fluorescent light fixtures for grow lights is well known. The fixtures commonly retain long tubular bulbs in a housing member positioned in proximity to growing plants to provide optimum illumination for germination and growth. Illumination and incidental heat from the light may be controlled through shading, on-off cycles, or simply by positioning the light more closely or further from the plants. Accordingly, some grow light systems provide a degree of flexibility in positioning the light fixture relative to the plants. However, there is as yet unknown to the present inventor a hanging tubular bulb grow light fixture that provides infinite overhead (vertical) adjustability. The adjustable height light fixture of the present invention provides such an advantage.
According to the present invention, there is provided an adjustable height grow light having infinite vertical adjustability with only the slightest force applied either to raise the light or to lower it. The preferred embodiments of the light include a light stand having vertical support members and horizontal feet and for stabilizing the stand, and a horizontal support member interposed between the vertical support members from which a light fixture hangs. A first line is routed over a first line axle and rotatable axle sleeve and a shared or common axle and axle sleeve, and a second line is routed over a second line axle and rotatable axle sleeve, and also over the shared axle sleeve. After passing over the shared axle sleeve, each of the lines is connected to a constant force ribbon torsion spring with a coupling block. The ribbon torsion spring is set within the horizontal support member on fourth fixed axle. In a second preferred embodiment the common axle sleeve and shaft are eliminated.
In each of the preferred embodiments, the constant force ribbon torsion spring is selected and fabricated to have a tension rating slightly exceeding the total weight of the light fixture and installed bulbs. This permits the fixture to be moved upwardly and downwardly with very little force and to remain securely in place at any of an infinite number of selected positions within its range without the use of position locking means. The fixture remains level due to the line scheme employed.


Disclosed is a trench formation technique wherein an opening having a first sidewall with planar contour and a second sidewall with a saw-tooth contour is etched through a semiconductor layer and into a semiconductor substrate. Then, a crystallographic wet etch process expands the portion of the opening within the semiconductor substrate to form a trench. Due to the different contours of the sidewalls and, thereby the different crystal orientations, one sidewall etches faster than the other, resulting in an asymmetric trench. Also disclosed is a bipolar semiconductor device formation method that incorporates the above-mentioned trench formation technique when forming a trench isolation region that undercuts an extrinsic base region and surrounds a collector pedestal. The asymmetry of the trench ensures that the trench isolation region has a relatively narrow width and, thereby ensures that both collector-to-base capacitance Ccb and collector resistance Rc are minimized within the resulting bipolar semiconductor device.

The methods and structures disclosed herein are related to trenches for use, for example, in trench isolation regions of semiconductor devices (e.g., for bipolar semiconductor devices, such as bipolar junction transistors (BJTs) or heterojunction bipolar transistors (HBTs)) and, particularly, to a method of forming an asymmetric trench, to a method of forming a bipolar semiconductor device having an asymmetric trench isolation region and to the resulting bipolar semiconductor device structure.
Those skilled in the art will recognize that it is desirable in bipolar semiconductor devices, such as bipolar junction transistors (BJTs) and, particularly, in high performance heterojunction bipolar transistors (HBTs), to have a relatively high transit frequency fT and maximum oscillation frequency fmax. fmax is a function of fT as well as various parasitic capacitances and resistances including, but are not limited to, parasitic collector-to-base capacitance Ccb and parasitic collector resistance Rc. Reduction of the parasitic capacitances and resistances can result in a higher fmax. Thus, it would be advantageous to provide an improved bipolar semiconductor device, such as a bipolar junction transistor (BJT) or heterojunction bipolar transistor (HBT), in which collector-to-base capacitance Ccb and collector resistance Rc are both minimized as well as a method of forming such an improved bipolar semiconductor device.

Formation of an asymmetric trench in a semiconductor substrate and a bipolar semiconductor device having an asymmetric trench isolation region

International Business Machines Corporation


Apparatus and methods for calibrating radio frequency transmitters to compensate for common mode local oscillator leakage are provided herein. In certain configurations herein, a transmitter generates a radio frequency transmit signal based on mixing a baseband input signal with a local oscillator signal. The transmitter is calibrated to compensate for common mode local oscillator leakage. Thus, a common mode component of the local oscillator signal is reduced or eliminated from the radio frequency transmit signal, which provides a number of benefits, including lower levels of undesired emissions from the transmitter.

Transceivers are used in radio frequency (RF) communication systems to transmit and receive signals associated with a wide variety of communication technologies, such as cellular and/or wireless local area network (WLAN) technologies.
Examples of RF communication systems with one or more transceivers include, but are not limited to, base stations, mobile devices (for instance, smartphones or handsets), laptop computers, tablets, and wearable electronics.
A transceiver includes a transmitter for transmitting RF signals and a receiver for receiving RF signals. To improve the transceiver's performance, the transceiver can be calibrated to compensate for impairments. Calibrating the transceiver in this manner can decrease error vector magnitude (EVM), reduce out of band emissions, and/or otherwise enhance the performance of the transceiver.


The intensity of a beam of light used to etch concentric servo tracks on a magnetic medium is adjusted with an acousto-optical device to maintain a substantially constant energy density delivered by the beam while the optics which generate the beam move radially of the disk.

So-called "floppy" disk memory systems for "desk top" sized computers are well known in the art. Such systems employ magnetic storage disks having a diameter of either 5.25 inches or 3.50 inches. Conventional magnetic storage disks for floppy disk drives have a track density ranging from forty-eight (48) to one hundred thirty-five (35) tracks per inch (TPI). In contrast, optical storage disks for optical memory systems achieve track densities greater than 15,000 TPI. The greater track density of optical disks is achieved by the use of optical servos that maintain fine positioning of the optical read/write head over the data tracks on the disk. Typically, concentric optical servo tracks are prerecorded on the optical disk to guide the servo mechanism.
New advances in barium-ferrite magnetic media have allowed bit densities of magnetic storage disks to exceed the bit densities of optical disks. However, as mentioned above, track densities of magnetic media (48-135 TPI) are many times less than their optical counterparts. This limits the overall capacity of magnetic disks as compared to optical disks. Conventional magnetic disk systems employ a magnetic servo mechanism and magnetically prerecorded servo tracks on the disks to guide the read/write head. Magnetic servo systems cannot provide the fine positioning that optical servo systems can provide.
Recently, floppy disk systems have been developed that combine magnetic disk recording techniques with the high track capacity optical servos found in optical disk systems. Such a system is described in AN INTRODUCTION TO THE INSITE 325 FLOPTICAL(R) DISK DRIVE, Godwin, in a paper presented at the SPIE Optical Data Storage Topical Meeting (1989). Essentially, an optical servo pattern is prerecorded on a magnetic floppy disk. The optical servo pattern typically consists of a large number of equally spaced concentric tracks about the rotational axis of the disk. Data is stored in the magnetic "tracks" between the optical servo tracks using conventional magnetic recording techniques. An optical servo mechanism is provided to guide the magnetic read/write head accurately over the data between the optical servo tracks. By utilizing optical servo techniques, much higher track densities are achievable on the relatively inexpensive removable magnetic medium.
As mentioned, the optical servo pattern typically consists of a large number of equally spaced concentric tracks about the rotational axis of the disk. As disclosed in U.S. Pat. No. 4,961,123, each track may be a single continuous groove (FIG. 3), a plurality of equally spaced circular pits (FIG. 8), or a plurality of short equally spaced grooves or stitches (FIG. 9). Various methods and systems exist for inscribing the optical servo tracks on the magnetic medium.
For example, U.S. Pat. No. 5,067,039, entitled "High Track Density Magnetic Media with Pitted Optical Servo Tracks and Method for Stamping the Tracks on the Media," discloses a method for "stamping" the servo tracks on the magnetic medium. Essentially a master stamping disk is produced bearing a template of the optical servo pattern. This master disk is then pressed against the magnetic floppy disk under a pressure of several tons per square inch. The significant amount of pressure transfers the servo track pattern from the master disk to the floppy.
U.S. Pat. No. 4,633,451, entitled "Optical Servo for Magnetic Disks," discloses a method of providing optical servo information on a magnetic medium consisting of a multi-layer film. The optical servo tracks are formed on the multi-layer film by laser heating the structure to cause a reaction or interdiffusion to occur between layers. The reaction produces a reflectivity contrast of about eight percent (8%) between exposed and unexposed areas. Other methods for preparing the servo tracks are mentioned including contact printing, embossing, and lithography.
U.S. Pat. No. 4,961,123, entitled "Magnetic Information Media Storage with Optical Servo Tracks," discloses a preferable method and apparatus for etching the pattern on a disk using a focused beam of light. The magnetic disk is placed on a platen/spindle assembly and rotated. A beam of light is focused to a small spot on the spinning disk. The focussed beam has sufficient intensity to ablate the disk surface at that spot, thereby reducing the reflectivity of the surface at that spot, and as the disk rotates, a groove is produced. The beam can be left on during an entire revolution to produce a continuous groove or can be modulated on and off through one revolution to produce a stitched pattern of non-continuous grooves.
With the preferred etching method described above, the width of the etched grooves that define each servo track is a function of the energy density, ED, delivered by the incident beam to the focused spot on the disk. The energy density, ED, delivered by the beam is proportional to the intensity of the beam, I.sub.o, within the focused spot divided by the area of the spot, A.sub.o, multiplied by the linear velocity V.sub.1 of the disk at the focused spot. That is, ##EQU1## The linear velocity, V.sub.1, of the rotating disk at the focused spot is a function of the radius, r, of the particular groove or servo track being etched. That is, EQU V.sub.1 =2.pi.r.times.b,
where b is the "spin velocity" of the disk in revolutions-per-minute (rpm).
Typically, the groove width is on the order of microns and must be maintained within tight tolerances. For a single servo track, the energy density at the focused spot, and hence the width of the groove (or grooves w/ a stitched pattern), can be held constant simply by rotating the disk at a constant spin velocity, b. However, as the incident beam is moved radially of the disk to etch servo tracks at other radii, the change in radius results in a proportional change in the linear velocity of the disk surface at those radii. Therefore, if the disk rotates at a constant spin velocity, b, the energy density, ED, delivered to the surface of the disk will vary at different radii. Consequently, the groove width at different radii of the disk will vary significantly--an unacceptable condition.
One prior art method for compensating for the change in energy density at different track radii is to vary the rotational speed (rpm) of the disk to maintain a constant linear velocity despite the change in radius. Such a method is disclosed in the aforementioned U.S. Pat. No. 4,961,123 at column 10, lines 58-62. This method is disadvantageous, however, because etching must be suspended while the spindle motor settles to each new velocity. This prior art method results in lower throughput and requires high maintenance for the mechanical elements.
Another prior art method for compensating for the change in energy density is to vary the intensity of the incident beam at different radii by controlling the power supplied to the light source. Typically the light source is a laser. While varying the power supplied to the light source does alter the intensity of the beam, it also results in unacceptable beam wander and pointing stability.
Another possibility is to use a compensated neutral density wedge located in the path of the incident beam. Again, however, such a method results in unacceptable beam wander.
Thus, there is need for an apparatus and method of maintaining constant energy density at all radii of the disk, but which does not unacceptably reduce throughput and which does not require variation in the rotational speed of the disk. Additionally there is a need for an apparatus and method which does not produce undesirable beam wander. The present invention satisfies these needs.

Acousto-optical intensity control of laser beam during etching of optical servo information of magnetic media


Generating a situation-dependent library comprising a user's expected response to tokens representing stimuli that influence the user's affective state, including: receiving samples comprising temporal windows of token instances to which the user was exposed, wherein the token instances have overlapping instantiation periods and are spread over a long period of time that spans different situations; wherein at least one token is expected to elicit from the user a noticeably different affective response in the different situations; receiving target values corresponding to the temporal windows of token instances; the target values represent the user's responses to the token instances from the temporal windows of token instances; training a machine learning-based user response model using the samples and the corresponding target values; and analyzing the machine learning-based user response model to generate the situation-dependent library comprising the user's expected response to tokens, which accounts for the variations in the user's affective response in the different situations.

The last few years have witnessed many exciting developments in the area of affective computing, which involves systems that are capable of recognizing and analyzing the expression of human emotions. However, most of the affective computing systems are still research-grade endeavors that are typically not robust enough to handle the demands of real world applications.
A capability that is useful for many affective computing systems is being able to know a user's expected response to a stimulus. While there are currently systems for measuring user response to stimuli, they are usually inadequate when it comes to real world applications. The experimental data they collect is often generated in a controlled, virtually sterile, environment. In these laboratory-like settings, a small number of short experiments are conducted (typically less than an hour long), in which a user's reactions are measured to a set of pre-selected stimuli, such as pictures, video scenes, or music. The main drawback of the laboratory-collected data is that it is acquired over a short period of time, while the user is in a specific, controlled situation. However, in reality, a user's reaction to stimuli may vary dramatically depending on the situation the user is in, making the laboratory-collected data less useful. For example, a user's response while driving in busy traffic might be quite different from the user's response when relaxing at home, even if exposed to the very similar stimuli in both situations. Furthermore, in short experiments, a user's reaction can only be measured to a small number of stimuli, which is inadequate for creating an affective computing system for real world applications that may have to consider the effect of a wide range of stimuli from multiple sources.
Analyzing affective response data collected in real world scenarios poses new challenges that are not likely arise with data collected in controlled laboratory-like situations. For example, while in the laboratory the user's response is usually measured for a single stimulus at a time, in the real world, the user is simultaneously exposed to many stimuli of different types and originating from multiple sources. Another characteristic of data acquired in real world situations is that it is often incomplete. For instance, while the system may have good information regarding the stimuli the user is exposed to, it might not be able to get an accurate assessment of the user's response. This is especially true if the user's response is only available under certain conditions, for instance, when the user is facing a camera. Given the many challenges and complications involved in the real world domain, a system designed to accurately determine a user's expected response to stimuli in real world scenarios should take into account the added complexity intrinsic to this domain.

Situation-dependent libraries of affective response


A lithium battery and process of making same involves employing alternate layers of a lithium anode and an aluminum foil or NiAl expanded metal supported cathode assembly with a gel electrolyte contacting the alternate layers. The electrolyte includes a quantity of N-methyl-2-pyrrollidone and lithium contained within a polyimide matrix and the entire assembly is contained within a sealed polyimide casing. Separate electrical contacts are provided for each of the lithium anode assembly and the aluminum foil or NiAl supported cathode assembly. An out-gassing vent tube extends from the sealed polyimide casing and is sealed a predetermined time after battery construction.

Small, high energy-density, low voltage batteries are in great demand in the computer technology age in which we live. Many types of nickel-cadmium (Ni-Cd) and nickel-metal-hydride (NiMH) batteries are popular in personal computers, and other electronics, but the price excludes use of these battery types in low-cost products.
Ni-Cd rechargeable and amorphous (flexible, changing) solar batteries are also used extensively but the cost of these batteries is also of concern. Lithium-ion cells have also been produced that have twice the density of Ni-Cd batteries but are also expensive to make. There is a definite need in the art for an improved, economically mass-produced, rechargeable battery that has improved energy-density (energy per unit volume), output voltage, reversibility (ability to take a charge, and to be recharged), reliability, safety and cost properties.
It is therefore an object of the present invention to provide an improved, economical, high energy-density, low-voltage, composite lithium metal/lithium-ion battery.
Another object of the present invention is to provide a lithium battery that is adaptable for mass production and reliable in operation.
An additional object of the present invention is to provide a lithium battery that has significantly improved reversibility (rechargability) and safety characteristics compared to that of prior art lithium batteries.
A further object of the present invention is a novel process for economically making lithium batteries.


A spin-valve magnetoresistive sensor includes a free layer of a ferromagnetic material, a pinned layer provided on the free layer and a pinning layer of an anti-ferromagnetic material provided on the pinned layer, the anti-ferromagnetic material being an ordered alloy containing manganese. The pinned layer includes a first pinned layer of a ferromagnetic material, a second pinned layer of a ferromagnetic material provided on the first pinned layer and an intermediate layer interposed between the first and second pinned layers such that the first and second pinned layers establish a super-exchange interaction in an anti-parallel manner. The second pinned layer has a magnetic moment smaller than a magnetic moment of the first pinned layer.

1. Field of the Invention
The present invention generally relates to magnetic storage of information, and particularly to a spin-valve magnetoresistive sensor and a magnetic head having such a spin-valve magnetoresistive sensor.
2. Description of the Related Art
Presently, anisotropic magnetoresistive (AMR) sensors are used extensively for a magnetic head of a hard disk drive (HDD) apparatus. Due to the tendency of increasing recording density of magnetic recording apparatuses, there is a growing need for a magnetic head having a spin-valve magnetoresistive sensor, which provides a sensitivity superior to an AMR sensor.
FIG. 1 is a partially cut-away perspective diagram of a composite magnetic head 130 including the spin-valve magnetoresistive head 100 of the related art. The composite magnetic head 130 incorporates the spin-valve magnetoresistive head 100 as a reading (reproducing) head of the hard disk drive apparatus and also incorporates a writing (recording) head. FIG. 1 also shows a hard disk 27 as a recording medium. In the figure, the hard disk 27 is arranged so as to oppose the composite magnetic head 130. The basic structure of the composite magnetic head 130 is substantially the same as the structure of the composite magnetic head 30 of the present invention. Therefore, further detailed description is omitted here. The structure of the composite magnetic head 130 of the related art can be understood when reading the detailed description of FIG. 8 by replacing the spin-valve magnetoresistive head 10 with the spin-valve magnetoresistive head 100 of the related art.
FIG. 2 is a partially cut-away perspective view showing a spin-valve magnetoresistive head 100 using a spin-valve magnetoresistive sensor of the related art. Further, FIG. 3 is a side view showing the spin-valve magnetoresistive head 100 of FIG. 2. In the following, the spin-valve magnetoresistive head 100 will be described in detail with reference to FIGS. 2 and 3.
The spin-valve magnetoresistive head 100 includes a lowermost underlayer 111 of tantalum (Ta) and an uppermost capping layer 116 also of Ta, and a spin-valve magnetoresistive sensor is interposed between the underlayer 111 and the capping layer 116. The spin-valve magnetoresistive sensor (or film) includes a free layer 112 of a ferromagnetic material, a non-magnetic layer 113 of a non-magnetic conductive material such as copper (Cu), a pinned magnetic layer 114 of a ferromagnetic material such as a cobalt-iron-boron (CoFeB) alloy, and a pinning layer 115 of an anti-ferromagnetic material, which may be formed of an ordered alloy made of palladium-platinum-manganese (PdPtMn), in the state that the layers 112-115 are stacked consecutively on the underlayer 111. The free layer 112 typically includes a first ferromagnetic layer 112a of nickel-iron (NiFe) provided on the underlayer 111 and a second ferromagnetic layer 112b of a cobalt-iron-boron (CoFeB) alloy provided on the first ferromagnetic layer 112a.
In this context, the ordered alloy used for the pinning layer 115 is understood as an anti-ferromagnetic alloy which does not exhibit magnetism when initially formed as the anti-ferromagnetic layer 115. On the other hand, the ordered alloy exhibits a stable magnetization when its magnetization is aligned as a result of magnetizing process conducted under a suitable condition.
The above-described spin-valve magnetoresistive head is manufactured first by providing the underlayer and then providing other layers described above in the order shown in FIGS. 2 and 3. Then, all the layers including the spin-valve magnetoresistive sensor are patterned to form a rectangular body, and electrode terminals 117a, 117b of a metal such as gold (Au) are provided on the uppermost capping layer 116 with a mutual separation from each other.
In the spin-valve magnetoresistive head 100 of FIG. 3, the area between the electrodes 117a and 117b and designated as S serves as the signal sensing area of the spin-valve magnetoresistive sensor. In the following text, X-, Y-, and Z-directions are defined as follows in order to make a clear explanation of, for example, the magnetizing direction of the spin-valve magnetoresistive sensor of the spin-valve magnetoresistive head 100. Thus, the Z-direction is defined as a direction of the thickness of the spin-valve magnetoresistive sensor. The Y-direction is a direction perpendicular to the Z-direction. It should be noted that the foregoing electrodes 117a and 117b are provided at the respective opposite ends of the rectangular body forming the spin-valve magnetoresistive sensor in the cross-sectional view taken in the Y-direction. The X-direction (the height) is a direction perpendicular to the Y-Z plane.
In the following text, it is assumed that the magnetization of the free layer 112 points in the Y-direction in the state where there is no external magnetic field applied to the free layer 112. In other words, the free layer 112 has an easy axis of magnetization pointing in the Y-direction. Also, a term xe2x80x9corientationxe2x80x9d is understood to mean a predetermined direction, which may be shown by an arrow in the figures. A term xe2x80x9cdirectionxe2x80x9d can imply both opposite orientations having positive and negative signs.
During the operation of the spin-valve magnetoresistive head 100 of the related art, a sense current Is is caused to flow through the signal sensing region S between the two electrode terminals 117a, 117b, and the spin-valve magnetoresistive head 100 is caused to scan over a magnetic recording medium (not shown) such as a magnetic disk. Then, the electric resistance of the spin-valve magnetoresistive sensor changes in response to a signal magnetic field Hsig originating from the magnetic recording medium in the X-direction. Thus, the signal magnetic field of the magnetic recording medium can be detected as a change of the voltage appearing across the electrodes 117a and 117b.
With such a spin-valve magnetoresistive head 100, it is preferable that the resistance of the spin-valve magnetoresistive sensor changes linearly with respect to direction of the signal magnetic field Hsig such that the resistance increases when the signal magnetic field Hsig has a first orientation and such that the resistance decreases when the signal magnetic field Hsig has a second, opposite orientation It should be noted that the resistance of the spin-valve magnetoresistive sensor becomes minimum when the magnetization Mf of the free layer 112 and the magnetization Mp of the pinned magnetic layer 114 are parallel and becomes maximum when the magnetization Mf of the layer 112 and the magnetization Mp of the layer 114 are anti-parallel. In order to achieve this, the direction of magnetization Mp of the pinned magnetic layer 114 is pinned in the X-direction by establishing an exchange coupling between the pinned magnetic layer 114 and the anti-ferromagnetic layer 115. Then, when the signal magnetic field Hsig is zero, the direction of magnetization Mf of the free layer 112 points in the Y-direction as stated above.
Now, due to the increase in the recording density of the information recorded on a recording medium such as a hard disk, there is a tendency that the size of the individual magnetic spots formed on the magnetic disk becomes smaller and smaller, and because of this, the signal magnetic field Hsig which the spin-valve magnetoresistive head 100 is supposed to pick up tends to become very weak. In order to compensate for the weakening of the signal magnetic field Hsig, it is necessary to increase the magnetic resistance ratio (MR-ratio) xcex94 xcfx81/xcfx81 to obtain a larger signal or S/N ratio. In order to achieve this, either the thickness (Z-direction) or the height of the sensor (X-direction) of the spin-valve magnetoresistive sensor has to be reduced.
Firstly, a process of reducing the thickness (Z-direction) is considered. The layer having the greatest thickness in the spin-valve magnetoresistive sensor is the anti-ferromagnetic layer 115, which generally requires a thickness of more than 200 xc3x85. If the thickness of the anti-ferromagnetic layer 115 is less than 100 xc3x85, the exchange coupling magnetic field for fixing the orientation of magnetization Mp of the pinned magnetic layer 114 works little. Thus, there is a risk that the direction of magnetization Mp may be reversed easily by a disturbance such as an externally applied heat. Further, in view of maintaining the magnetic proper necessary for the spin-valve magnetoresistive sensor, each of the pinned magnetic layer 114 and the free layer 112 has to have a sufficient thickness. Therefore, there is a limitation in reducing the thickness of the pinned magnetic layer 114 or the thickness of the free layer. 112.
Secondly, a process of reducing the height of the sensor (X-direction) is considered.
Technically, it is possible to reduce the height of the layers. However, when the height of the sensor becomes too small, the distance between the side edges of the pinned magnetic layer 114 extending in the Y-direction becomes so small that the effect of so-called counteracting magnetic field becomes predominant. Then, the magnetic state of the pinned magnetic layer 114 becomes unstable and there arises a problem that the detection of the magnetic field becomes unstable.
Recently, in order to solve the problem related to counteracting-magnetic field, a spin-valve magnetoresistive sensor is proposed in which the pinned magnetic layer includes a first pinned magnetic layer, a second pinned magnetic layer, and an intermediate layer provided between the first and second pinned magnetic layers. However, with such a structure, a disordered metal of, for example, NiO is used as an anti-ferromagnetic layer. Therefore, the anti-ferromagnetic layer already exhibits a magnetic property at an instant when the pinned magnetic layer is stacked thereon. Accordingly, there are many problems in manufacturing a spin-valve magnetoresistive sensor while maintaining the above-described preferable relationship between the pinned magnetic layer and the free layer.
As has been described above, there are many problems related to development of the spin-valve magnetoresistive sensor. The present invention is related to a method in which the height of the sensor (X-direction) is reduced. More specifically, the present invention relates to a structure including a pinned magnetic layer having a first pinned magnetic layer, a second pinned magnetic layer, and an intermediate layer provided between the first and second pinned magnetic layers. Also, an alloy used for the anti-ferromagnetic layer in the present invention does not exhibit a magnetic property when initially produced as an anti-ferromagnetic layer, but will exhibit the magnetic property when its structure is aligned according to a magnetizing process under a certain condition.
The ordered alloy used for the anti-ferromagnetic layer does not exhibit a magnetic property directly after production of the spin-valve magnetoresistive sensor. The alloy is anti-ferromagnetized (aligned) after implementing a heat treatment in a magnetic field. Thus, the magnetization of the pinned magnetic layer can be fixed. The ordered alloy exhibits such a property due to the fact that the metal crystals will be aligned in a predetermined direction and thus undergoes a phase change from a face-centered cubic structure (fcc) to a face-centered tetragonal structure (fct).
With the spin-valve magnetoresistive sensor of the related art, since the magnetization of the pinned magnetic layer is fixed after the layers have been produced, the heat treatment is implemented while applying a magnetic field of over 2500 Oe (Oersted) in the X-direction. Then, in order to strengthen a magnetic anisotropic property of the free layer, a heat treatment is implemented while applying a predetermined magnetic field in the Y-direction.
However, when a magnetization process similar to that of the related art is implemented on a structure having pinned magnetic layer including a first pinned magnetic layer, a second pinned magnetic layer, and an intermediate layer provided between the first and second pinned magnetic layers, there arises a problem that the orientation of magnetization of the pinned magnetic layer deflects from the X-direction and inclines in the Y-direction. The orientation of magnetization of the pinned magnetic layer and the orientation of magnetization of the free magnetization layer are ideally mutually perpendicular, but an inclination of xc2x120 degrees from a right angle is allowable. However, with an inclination exceeding xc2x120 degrees, a linear output response cannot be achieved with respect to the input of an external signal magnetic field Hsig. Accordingly, there is a problem that a reproduction waveform of the output voltage is deformed.
Accordingly, it is a general object of the present invention to provide a spin-valve magnetoresistive sensor which can solve the above-described problems.
It is another and more specific object of the present invention to provide a spin-valve magnetoresistive sensor which can control the problems related to antimagnetic field and can solve the problems of the related art.
In order to achieve the above objects according to the present invention, a spin-valve magnetoresistive sensor includes:
a free layer of a ferromagnetic material;
a non-magnetic layer provided on the free layer;
a pinned layer provided on the non-magnetic layer; and
a pinning layer of an anti-ferromagnetic material provided on the pinned layer, the anti-ferromagnetic material being an ordered alloy containing manganese.
The pinned layer includes:
a first pinned layer of a ferromagnetic material;
a second pinned layer of a ferromagnetic material provided on the first pinned layer; and
an intermediate layer interposed between the first and second pinned layers such that the first and second pinned layers establish a super-exchange interaction in an anti-parallel manner.
The second pinned layer has a magnetic moment smaller than a magnetic moment of the first pinned layer.
With the spin-valve magnetoresistive sensor described above, by using an ordered alloy including manganese as an anti-ferromagnetic layer, a preferable relationship between the above-described pinned magnetic layer and the free layer can be easily achieved. Accordingly, with a multilayered pinned magnetic layer, the spin-valve magnetoresistive sensor can be further miniaturized and thus can achieve a thin-film structure of reduced thickness.
It is still another object of the present invention to provide a method of manufacturing a spin-valve magnetoresistive sensor of the above-described type.
In order to achieve the above object, a method of manufacturing a spin-valve magnetoresistive sensor includes the steps of:
a) forming a multilayered body in an order of the free layer, the non-magnetic layer, the first pinned layer, the intermediate layer, the second pinned layer, and the anti-ferromagnetic layer;
b) implementing a first heat treatment within a magnetic field for regulating a magnetic state of the pinning layer and for fixing an orientation of magnetization of the first and second pinned layers; and
c) implementing a second heat treatment within a magnetic field for regulating a magnetic anisotropic property of the free layer in an environment with a lower temperature and a weaker magnetic field than in the first heat treatment within the magnetic field.
It is yet another object of the present invention to provide a spin-valve magnetoresistive sensor in which a heat treatment in a magnetic field, which is similar to that of the double-layered pinned layer, can be applied to a single-layered pinned layer of the related art.
In order to achieve the above object, a magnetic head having a spin-valve magnetoresistive sensor includes:
a free layer provided on the non-magnetic layer,
a non-magnetic layer provided on the free layer;
a pinned layer provided on the non-magnetic layer; and
a pinning layer of an anti-ferromagnetic material provided on the pinned layer, the anti-ferromagnetic material being an ordered alloy containing manganese;
The direction of magnetization of the pinned magnetic layer and an easy axis of magnetization of the free layer are at a right angle or within xc2x120 degrees of the right angle. The pinned layer has an effective anisotropic magnetic field Hua of a magnitude of greater than or equal to about 600 Oe.
With the structure described above, the orientation Mf of the magnetization of the free layer rotates with respect to a signal magnetic field Hsig from an external magnetic recording medium. Thus, the resistance of the spin-valve magnetoresistive sensor can be changed linearly.
The present invention further relates to a magnetic head having the spin-valve magnetoresistive sensor described above and a magnetic recording medium drive apparatus having a magnetic head provided with a spin-valve magnetoresistive sensor.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.

Spin-valve magnetoresistive sensor and magnetic head having such a spin-valve magnetoresistive sensor


A new polishing and buffing attachment for applying polish and buffing of objects, especially wheel rims. The inventive device includes a head member having a outer padded layer. The first end of an elongate shank is extended into the interior of the head member from the second end of the head member such that the second end of the shank is outwardly extended from the second end of the head member. A cover member has an interior space and opposite first and second ends. The second end of the cover member has an opening into the interior space of the cover member. The head member is insertable through the opening of the second end of the cover member into the interior space of the cover member such that the second end of the shank member extends outwards from the opening of the second end of the cover member.

1. Field of the Invention
The present invention relates to polishing devices and more particularly pertains to a new polishing and buffing attachment for applying polish and buffing of objects, especially wheel rims.
2. Description of the Prior Art
The use of polishing devices is known in the prior art. More specifically, polishing devices heretofore devised and utilized are known to consist basically of familiar, expected and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which have been developed for the fulfillment of countless objectives and requirements.
Known prior art polishing devices include U.S. Pat. No. 5,297,366; U.S. Pat. No. 3,362,114; U.S. Pat. No. Des. 292,834; U.S. Pat. No. 4,149,294; U.S. Pat. No. 5,224,231; and U.S. Pat. No. 729,187.
While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not disclose a new polishing and buffing attachment. The inventive device includes a head member having a outer padded layer. The first end of an elongate shank is extended into the interior of the head member from the second end of the head member such that the second end of the shank is outwardly extended from the second end of the head member. A cover member has an interior space and opposite first and second ends. The second end of the cover member has an opening into the interior space of the cover member. The head member is insertable through the opening of the second end of the cover member into the interior space of the cover member such that the second end of the shank member extends outwards from the opening of the second end of the cover member.
In these respects, the polishing and buffing attachment according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of applying polish and buffing of objects, especially wheel rims.


A moisture vapor and oxygen transmission resistant flexible film has a polymeric base layer and a barrier layer of discrete particles of a first organic polymer dispersed throughout a matrix of a second organic polymer. Preferably, the first and second polymers are water insoluble and water soluble, respectively. The barrier layer is formed by depositing onto the base layer a coating composition of finely divided insoluble organic polymer particles suspended in an aqueous solution of the water soluble organic polymer, a crosslinking agent and surfactant. The coating composition is heated to crosslink the barrier layer polymers and evaporate solvent to provide a barrier film suitable for packaging applications. Optionally, the film can be metalized to increase barrier properties.

In the food packaging and similar industries flexible films with barrier properties are used in large amounts to resist the transmission of water vapor and oxygen through the film. These barrier films typically have a base layer of a structurally strong material which is not very resistant to water vapor and oxygen transmission. Such films generally also include a barrier layer of a more water vapor and oxygen transmission resistant material.
Conventional barrier layers have a matrix phase of composition having an intrinsically high transmission resistance. To increase transmission resistance properties, a phase of discrete, fine particles are dispersed in the matrix phase. The dispersed phase particles are inorganic composition, such as clay, kaolin, vermiculite, silicates, and the like. It is generally understood that the dispersed phase particles are not particularly non-transmissive to water vapor and oxygen in and of themselves. However, they function to improve overall barrier film transmission resistance by providing discontinuities in the matrix and thus blocking the direct path of water and/or oxygen molecules migrating directly across the film. This causes such migrating molecules to take a tortuous, longer path which slows their flow from one side of the film to the other.
Use of inorganic particles in barrier films has certain drawbacks. Of some concern is an adverse effect observed in the process of making barrier films with an inorganic particle dispersed phase. The matrix phase is quite often a crosslinked polymeric composition of an intrinsically transmission resistant component. Polyvinyl alcohol (PVOH) and ethylene vinyl alcohol copolymer (EVOH) are preferred polymers. Usually the inorganic particles are dispersed in a liquid coating solution that is deposited onto the base layer and dried to form the barrier layer, A preferred solvent is water. A thermally activated crosslinking agent can be included to promote the crosslink reaction of the polymers which are dissolved substantially uncrosslinked in the solvent.
A problem arises when the inorganic particles are dispersed in the polymer matrix. A sharp rise in viscosity occurs at very low inorganic particle concentrations due to ionic charges that are inherent in inorganic mineral particles such as mica and vermiculite. This significant viscosity increase inhibits handling of the solution and the formation of a uniform and desirably thin barrier layer. High viscosity is particularly problematic when coating the wet barrier layer composition onto the base layer with gravure coating technology. There is a need to provide an effective moisture vapor and oxygen barrier transmission resistant coating and barrier film that does not suffer from excessive viscosity buildup using existing production equipment and process techniques.
U.S. Pat. No. 7,737,200 relates to a stable, aqueous barrier composition which comprises prolamine; cold water insoluble polymer; water; water-soluble co-solvent; and stabilizer. The composition, when applied to a substrate, produces an article having a high surface energy and resistance to oil and grease penetration.
U.S. Pat. No. 7,521,103 discloses a coating comprised of a first polymer reacted with a second polymer optionally using a crosslinker. For example, the first polymer may comprise a copolymer of polyvinyl alcohol and a vinylamine. The second polymer may comprise a copolymer of a maleic acid and an acrylic acid. The coating is present on the polymer film in an amount sufficient to increase the oxygen barrier properties of the film.
U.S. Pat. No. 7,501,471 describes a blend comprising a poly(vinyl alcohol) stabilized vinyl acetate-ethylene polymer emulsion and a paraffin wax emulsion. A dried coating of the blend on a substrate has a hydrostatic head barrier sufficient to prevent passage of fluids but allows passage of water vapor through it. The vinyl acetate-ethylene polymer emulsion comprises a polymer containing 70 to 95 wt % vinyl acetate and 5 to 30 wt % ethylene, based on the total weight of monomers in the polymer. The paraffin wax in the paraffin wax emulsion has an average particle size of at least 0.3 microns.
U.S. Pat. No. 7,473,729 describes an article comprising an acrylic nanocomposite film adhered to a substrate. The acrylic nanocomposite film comprises (a) a non-elastomeric acrylic polymer; and (b) an acid-treated, layered silicate filler material which has an aspect ratio of at least about 25.
U.S. Pat. No. 7,303,797 discloses a coating layer for increasing the gas barrier performance of rigid shaped containers and films. The coating layer includes a water-borne composition comprising a water-soluble or water dispersible organic binder in the optional presence of a cross-linking agent. The organic binder includes from 10% up to less than 90% by weight, based on the dry weight of the coating layer, of an inorganic laminar mineral selected from montmorillonite, laponite, organo-modified montmorillonite and mixtures thereof.
U.S. Pat. No. 5,981,029 describes a gas barrier film with a barrier coating. The film that provides high gas barrier ability at high humidity and under elongation, and also has durability of gas barrierability, and also with adhesiveness and post-lamination gas barrierability. The film is suggested for packaging material highly reliable in preservability. The barrier coating has inorganic stratified particles that may be provided by inorganic particles formed by overlapping one to several very thin unit crystal layers. Among them, especially, a clay is preferably used.

Multilayer barrier film having coating composition with organic particles


The threshold system includes a first support member secured to a walking surface, a second support member secured to the walking surface, and a thermal break joining the first support member and the second support member. A first ramp is removably coupled to the first support member. A second ramp is removably coupled to the second support member.

The use of thresholds in residential and commercial buildings is an integral part of conventional construction. External doors are most effectively mounted in conjunction with a lower plate or threshold member above which the door may be oriented in a closed position. The threshold may serve multiple functions. For example, the threshold reduces a distance between a surface above which the door swings and a bottom of the closed door. The threshold may also function as a barrier to air and moisture infiltration. In some designs, sealing members are incorporated with the door to reduce or substantially eliminate moisture infiltration under the closed door.
In certain applications, a threshold for a doorway may need to meet certain design requirements. For example, the Americans with Disabilities Act ("ADA") sets forth certain requirements for thresholds to minimize an impact a threshold might have on a person having disabilities ability to pass through the doorway. One such requirement is to reduce a height of the threshold relative to a walking surface upon which the threshold is installed. In order to maintain a low height difference between the threshold and the walking surface, prior thresholds have required modification of the walking surface. For example, the walking surface may either be raised to abut edges of the threshold or a portion of the walking surface may be cut out and removed to form a groove or trough for the threshold to sit in. Incorporating a threshold system using either of these ways can lead to problems. For example, it can be difficult to provide a seal to prevent water from accumulating underneath the threshold. Accumulated water can induce other problems like mildew or mold. Furthermore, for some walking surfaces it may not be desirable or permitted to modify the walking surface with cuts and the like. Therefore, a threshold system that complies with requirements of the ADA, is installable with minimal alteration of the walking surface, and provides an accessible seal to prevent water from accumulating underneath the threshold is desirable.