The invention provides a non-stage transmission which shifts gear in response to a load without requiring any independent actuator for changing a change gear ratio, and can achieve a large change gear ratio on the basis of a small-sized and low-cost structure.

In conventional, there has been widely known a non-stage transmission as a variable speed gear which can be always used in a high efficiency point of a power source and smoothly carries out a shift transmission. As a most prevail non-stage transmission, there is a structure which is constituted by a V-shaped belt and two pulleys having variable V-shaped grooves, and achieves a continuous change gear ratio by continuously changing a width of the V-shaped grooves. However, in the prior art mentioned above, an independent actuator (for hydraulic, motor) for changing the width of the variable V-shaped grooves of the pulley is required, it is hard to make the structure compact, and a high cost is required. Further, since a radius of curvature equal to or more than a certain level is required in the V-shaped belt, it is impossible to secure a large change gear ratio. Accordingly, an object of the present invention is to provide a non-stage transmission which does not require any independent actuator for shifting gear, has a small size and a low cost, and can secure a large change gear ratio, and a device having the non-stage transmission. In this case, the relation (change gear ratio)=(input side rotational speed)/(output side rotational speed) is established.

Non-stage transmission and device having non-stage transmission

Abstract: The non-stage transmission is structured such that a rocker arm 4 is reciprocated via a connection rod 18, a means for changing a stroke of the reciprocating motion is provided, and an output shaft 2 is driven in one direction whichever of forward and backward directions of the reciprocating motion of the rocker arm 4. An input side turning body 13 is structured such as to drive an output side turning body 14 via an energizing spring 12. The stroke of the reciprocating motion is changed by rotating a crank shaft lever by a cam groove 13d in a clockwise direction in correspondence to an increase of a load so as to shorten a distance between points Q, S. A torque and a rotational number of the output shaft are changed on the basis of a change of the stroke.


A semiconductor device fabrication process comprising an encapsulation step of carrying out encapsulation by vacuum pressure differential printing by the use of a liquid resin encapsulant containing a solvent in an amount of from 5% by weight to 50% by weight, and preferably from 25% by weight to 50% by weight. The encapsulation step comprises: printing the liquid resin encapsulant by vacuum pressure differential printing in such a way that; the encapsulant covers at least an internal connecting terminal provided on a substrate, a semiconductor chip, and a wire interconnecting the internal connecting terminal and the semiconductor chip; and that the thickness of the encapsulant lying above the wire at the highest position of the wire comes to be at least 0.8 times the thickness of the encapsulant lying beneath the wire at the same position; and curing or drying the encapsulant.

1. Field of the Invention
The present invention is related to a semiconductor device and a method of fabrication thereof.
2. Description of the Related Art
There is a growing need for a smaller semiconductor device package with multiple terminal pins due to increases of an integration rate and an operation frequency in the recent semiconductor device. However, a package size of a conventional peripheral terminal type utilizing a leadframe has to be made larger if a number of the terminals should be increased further. One of countermeasures is to decrease a terminal pitch in the package. However, it is difficult to make the terminal pitch narrower than 0.4 mm.
To accommodate such increasing number of the terminals, an area array type package with its terminals disposing over a surface plane is introduced. The area array type package requires to have a wiring substrate for providing wiring from chip terminals to external terminal electrodes. The chip may be mounted either at the upper surface or the lower surface of the wiring substrate when the external terminal electrodes are disposed at the lower surface of the wiring substrate. When the chip is mounted on the upper surface of the wiring substrate, interlayer connections between the upper surface and the lower surface of the wiring substrate have to be provided. When the chip is mounted on the lower surface of the wiring substrate, the interlayer connections will not be required. However, a hollow space has to be provided to absorb total thickness of the chip and its sealing material when the chip is mounted on the lower surface of the wiring substrate.
The hollow space is called a cavity, and a structure with the cavity at the lower surface of the wiring substrate is called a cavity down structure. Typically, the structure can be made by hollowing out a substrate, or by making a hole through the substrate and adhering a base plate thereto. Wiring for a multiple layer structure is required when heights of chip bonding portions and external electrodes are changed because the wiring is also disposed on the same surface in this structure. According to the methods described above, a wiring structure, which satisfies required conditions for a three dimensional spatial relationships among the chip mount portion, the chip bonding portion and the external electrode portion.
One of the area array type semiconductor package is Ball Grid Array (BGA) in which solder balls are used as connection terminals. Cost of the BGA is higher than that of a semiconductor device fabricated with a conventional leadframe, and reduction of the cost is anticipated. The higher cost is due to a fact that a structure and fabricating process of the semiconductor chip package substrate are more complex than that of a substrate with the leadframe. Accordingly, it is anticipated the development of simpler structure and fabricating process of the semiconductor chip package substrate.
The wiring substrate used for the area array type semiconductor package is typically called an interposer. The interposer may be roughly classified into a film type and a rigid type. A number of the wiring layers can be either one, or two, or three and more layers. Generally, the fabricating cost is lower for a fewer number of the wiring layers.
The lowest cost is expected with the single layer wiring structure. If the wiring is disposed at least in both surfaces of the interposer, the semiconductor chip mount portion and the external terminals may be divided at the upper and the lower surfaces. However, the semiconductor chip mount portion and the external terminals are disposed on the same surface of the interposer with the single layer wiring structure. In such a single layer wiring structure, it is required to have the cavity portion on the wiring surface with a depth at least comparable to a thickness of the chip so as to store the chip therein. A method of fabricating such a cavity portion has become an important subject.
In the interposer so called TAB (Tape Automated Bonding) or TCP (Tape Carrier Package) and their packaging technology, the center portion of the interposer is bored through to store the semiconductor chip. With the rigid plate, the center portion of the interposer is similarly bored through to hollow the semiconductor chip store portion out and adhere a metal plate as the base plate thereto, or the cavity portion is fabricated at the center portion of the interposer. The wiring is disposed only in a flat plane portion, not inside the cavity portion.
In conventional semiconductor devices employing lead frames, transfer molding has been in wide use for their fabrication. However, in the fabrication of semiconductor devices in recent years where semiconductor chips are mounted on substrates, the transfer molding, which requires expensive and long-time-to-delivery molds, has become adaptable with difficulty though still used in some cases, because it is difficult for the substrates used and package structure to be standardized.
Accordingly, liquid resin encapsulation (sealing) is highlighted which requires no mold and is suited especially when small quantity and many kinds of products are manufactured in a short time to delivery. Dispensing, printing and vacuum pressure differential printing are known as chief methods for such encapsulation making use of a liquid resin encapsulant (sealant).
FIG. 24C perspectively illustrates an encapsulation target where a semiconductor chip 1 is mounted on a substrate 7 and this chip 1 and a conductor wiring 2 are connected through wires 3 by wire bonding. In conventional dispensing, as shown in FIG. 24A, a solder resist 25 is provided on the surface of the conductor wiring 2 of this chip-mounting substrate. On that surface an encapsulation dam 26 is provided as shown in FIG. 24B, and a liquid resin encapsulant 4 is poured therein to encapsulate the chip 1 as shown in FIG. 24D. In this method, however, especially in the case of fine-pitch wire bonding, the resin encapsulant 4 may come around with difficulty beneath the wires 3 at the time of encapsulation to tend to cause encapsulation defects 20 such as air bubbles and faulty filling, also resulting in a low productivity.
Printing is known as a liquid resin encapsulation method that can achieve a productivity comparable to that of transfer molding. The printing is a method in which as shown in FIG. 25A an encapsulant 4 is printed via a printing mask 28 and thereafter as shown in FIG. 25B the printing mask 28 is removed, whereby a chip 1 is encapsulated. This method promises a high productivity, but, in the case of fine-pitch wire bonding, tends to cause encapsulation defects 20 such as faulty filling and air bubbles beneath bonded wires 3 or at the part with complicated or delicate internal structure.
As a method for solving this problem to achieve improvement greatly, there is vacuum pressure differential printing, which has been invented so that printed portions with complicated internal structure can be filled with a printing resin without leaving any air bubbles.
In this method, the whole printing portions, i.e., part or the whole of a printing device, a printing mask 28, a liquid resin encapsulant 4, and a printing-target wiring substrate 1 with a semiconductor chip mounted thereon, and so forth, are placed in a vacuum container, where first-time printing is carried out firstly in the state the vacuum container is kept at a high vacuum (FIG. 26A). When left in this state, any delicate areas of printed portions can be filled with the resin with difficulty, so that an empty space 21 may remain.
Accordingly, the vacuum container is then brought to medium-vacuum condition, whereupon the high-vacuum empty space 21 not filled with the resin at the first-time printing is crushed up to the medium-vacuum condition to become almost free of the empty space 21 and simultaneously a depression 22a appears at the resin surface to an extent corresponding to the resin with which the open space has been filled (FIG. 26B).
In that state, second-time printing is carried out as it is kept in medium vacuum, to fill up the depression 22a of the resin surface (FIG. 26C). Thereafter, the vacuum is returned to atmospheric pressure, the printing mask 28 is removed, and the printed article is taken out, thus the resin encapsulation is completed.
During the first-time printing (FIG. 26A) carried out in high vacuum, the empty space 21 comes into being where the resin has not been packed into any delicate areas lying beneath bonding wires. Here, if the resin layer lying above the empty space 21, i.e., the resin layer formed on the bonding wires 3 has a thickness smaller than the depth of the high-vacuum empty space 2121 lying beneath the wires 3, the resin layer may break when the resin is sucked in the high-vacuum empty space 21 during the printing carried out in medium-vacuum condition, so that the empty space or air bubbles 22 kept in medium vacuum may remain in the resin (FIG. 26B). This phenomenon is called a pressure differential short circuit.
Even if in this state the resin for the portion of the depression, corresponding to the resin sucked therein, is supplied by the second-time printing, air bubbles 20 may remain as shown in FIG. 26C, at the time the vacuum is returned to atmospheric pressure. In order to prevent the pressure differential short circuit from being caused when returned to medium vacuum, the resin layer on the bonding wires 3 may beforehand be formed in a sufficiently large thickness. However, a resin layer merely made to have a large thickness makes the package have too large a thickness, and also may bring about a difficulty in the mounting on a mother board because of a protrusion of encapsulation resin when the encapsulation surface and the external terminal surface are identical.
Thus, the vacuum pressure differential printing, though promising a high productivity and usually less causing encapsulation defects, has had a problem that the encapsulation defects (such as air bubbles) 20 tends to come into being once the pressure differential short circuit has occurred.
An object of the present invention is to obtain a semiconductor device that is compact and inexpensive, has a high reliability and makes it easy to standardize designing and fabrication steps, without causing any encapsulation defects.
The present invention provides a semiconductor device fabrication process comprising an encapsulation step of carrying out encapsulation by vacuum pressure differential printing by the use of a liquid resin encapsulant containing a solvent in an amount of from 5% by weight to 50% by weight, and preferably from 25% by weight to 50% by weight.
The fabrication process of the present invention may further be provided, before the encapsulation step, with;
a mounting step of mounting a semiconductor chip on a substrate having on its surface a surface wiring and a first hollow place (cavity portion), being provided with a second hollow place in a bottom area of the first hollow place and having an internal connecting terminal on the inner wall of the first hollow place; the semiconductor chip being mounted in a bottom area of the second hollow place; and
a wire-connecting step of interconnecting the internal connecting terminal and the semiconductor chip through a wire. Here, the encapsulation step is the step of encapsulating at least the internal connecting terminal, the semiconductor chip and the wire. Also, the wire may preferably be held in the interior of the first hollow place and second hollow place (i.e., the wire is positioned lower than the surface of the substrate on which the surface wiring is provided).
The encapsulation step in the fabrication process of the present invention may preferably be the step of printing a liquid resin encapsulant by vacuum pressure differential printing in such a way that the encapsulant covers at least the internal connecting terminal provided on the substrate, the semiconductor chip, and the wire interconnecting the internal connecting terminal and the semiconductor chip, and that the thickness of the encapsulant lying above the wire at the highest position (hereinafter xe2x80x9cthe apexxe2x80x9d) of the wire (i.e., at the position close to the encapsulant surface or the surface laid bare to the atmosphere), i.e., the thickness extending from the apex of the wire to the encapsulant surface (the surface laid bare to the atmosphere) comes to be at least 0.8 time the thickness of the encapsulant lying beneath the wire at the same position (i.e., the thickness extending from the apex of the wire to the bottom of the encapsulated portion), and curing or drying the encapsulant.
The present invention also provides a semiconductor device comprising;
a substrate having on its surface a surface wiring and a first hollow place, being provided with a second hollow place in a bottom area of the first hollow place and having an internal connecting terminal on the inner wall of the first hollow place;
a semiconductor chip bonded to a bottom area of the second hollow place;
a wire interconnecting the internal connecting terminal and the semiconductor chip; and
an encapsulation member which encapsulates at least the internal connecting terminal, the semiconductor chip and the wire.
Here, the wire may preferably be held in the interior of the first hollow place and second hollow place (i.e., the wire are positioned lower than the surface of the substrate on which the surface wiring is provided). Also, the sidewall of the first hollow place may preferably has a slant, and the wire interconnecting the surface wiring and the internal connecting terminal are provided at the slant.
The present invention still also provides a liquid encapsulant comprising a solvent contained in an amount of from 5% by weight to 50% by weight, and preferably from 25% by weight to 50% by weight, and its use in vacuum pressure differential printing. The present invention is suitable for a semiconductor chip package substrate with a cavity portion, or a semiconductor device fabricated by mounting at least one semiconductor chip in the cavity portion and sealing with plastic sealant, wherein said semiconductor chip package substrate comprises wiring disposed along a surface of the substrate and wall surfaces of the substrate in the cavity portion, the wiring comprises an external connection terminal portion for connecting to external connection terminals which are provided on the surface of the substrate at a side of the cavity portion""s opening, an internal connection terminal portion for connecting to the mounted semiconductor chip, and a wiring portion disposed in between the external connection terminal portion and the internal connection terminal portion, the wiring portion is buried in a surface of the substrate and one of said wall surfaces of the substrate in the cavity portion and the internal connection terminal portion is disposed inside of the cavity portion.
For example, the wall surface of the substrate in the cavity portion may be extended toward the bottom surface of the cavity portion with a slant angle which is set within a predetermined angle range. Concretely, the slant angle may be within a range of 5-40xc2x0, and preferably within a range of 10-40xc2x0. The slant structure may be fabricated so as that a ratio L/G is within a range of 1.5 less than L/G less than 10, where G is a height of the slant structure of the wall surface of the substrate in the cavity portion, and L is its horizontal dimension. More preferable range of the ratio L/G is 2 less than L/G less than 10, and the most preferable range is 3 less than L/G less than 10.
The cavity portion is, for example, formed by a press forming process utilizing a press pattern with a projected portion. The cavity portion may also be formed into a multiple step structure.
Alternatively, the cavity portion may be provided with a semiconductor chip mount portion for mounting semiconductor chip, which is formed by hollowing the cavity portion out further. A depth of the semiconductor chip mount portion which has been hollowed out is preferably larger than a thickness of a semiconductor chip to be mounted therein.
Furthermore, a height of a ramp between the external connection terminal portion disposed on the substrate surface and the internal connection terminal portion disposed inside of the cavity portion may be preferably not less than 0.05 mm in the semiconductor chip package substrate and the semiconductor device according to the present invention.
The terminals of the semiconductor chip mounted inside of the cavity portion and the internal connection terminal portions are wire-bonded, or, directly connected by a face-down bonding.
Furthermore, the wiring in the semiconductor chip package substrate and the semiconductor device according to the present invention may be preferably disposed in an area of the wall surface which does not include any of corner sections of the cavity portion.
Furthermore, the cavity portion may be formed substantially at the center of the major surface plane of the substrate, and the semiconductor chip may be mounted inside of the cavity portion so as the semiconductor chip to be positioned substantially at the center of a dimension of the thickness of the semiconductor chip package substrate. Alternatively, the semiconductor chip may be offset-mounted in the cavity portion with an offset amount of not bigger than 30% of the substrate thickness from the center position of the substrate""s thickness along a direction of the thickness. The cavity portion may have a size large enough to mount a plurality of device elements on its bottom surface area, and may be provided with a plurality of wiring sets to the plurality of device elements, and a plurality of semiconductor chips and passive device elements may be mounted in the cavity portion.
Furthermore, the wiring in the semiconductor chip package substrate and the semiconductor device according to the present invention is preferably formed by utilizing a squeeze shapeable wiring construction body consisting of only metals, the squeeze shapeable wiring construction body having a multiple layer structure including at least the first metal layer for constructing the wiring and the second metal layer which functions as a carrier layer.
Furthermore, a depth of the cavity portion may be less than a thickness of the semiconductor chip to be mounted, and the cavity portion may be hollowed out at the bottom surface of the cavity portion from the center portion along a direction of a thickness of the semiconductor chip package substrate up to a depth within a range of 0.5-2.5 times a thickness of the semiconductor chip to be mounted. Alternatively, a depth of the cavity portion may be less than a thickness of the semiconductor chip to be mounted, and the cavity portion may be hollowed out at the bottom surface of the cavity portion, and the semiconductor chip package substrate may be further comprising a plastic layer formed by hardening prepregs so as to have an exposed hollowed-out bottom surface at least consisting of nonwoven fabrics.
In this case, a metal plate with a thickness of not less than 0.035 mm may be adhered to a reverse side of the plastic layer wherein the cavity portion was formed, a depth of the cavity portion may be made to be less than a thickness of the semiconductor chip to be mounted, and the bottom of the cavity portion may be hollowed out to expose the metal plate. Alternatively, a metal plate with a thickness of not less than 0.20 mm may be adhered to the reverse side of the plastic layer wherein the cavity portion was formed, a depth of the cavity portion may be made to be less than a thickness of the semiconductor chip to be mounted, and the bottom of the cavity portion may be hollowed out into the metal plate as much as the hollowed out depth in the metal plate is not less than 0.05 mm.
Furthermore, the hollow-out process of the plastic layer may be stopped before reaching the metal plate.
The above object of the present invention may be accomplished by a fabricating method of a semiconductor chip package substrate, comprising the steps of: pressing to adhere a squeeze shapeable wiring construction body to a plastic substrate, the wiring construction body consisting of all metals and having a multiple layer structure comprising at least the first metal layer and the second metal layer which functions as a carrier layer; coincidentally shaping the plastic substrate so as to form a cavity portion therein with its wall surfaces having inclination angles within a predetermined range; and removing the metal layers except the first layer; wherein the wiring, which is buried in the substrate surface and wall surface of the substrate in the cavity portion, is formed and disposed along the substrate surface and the wall surface of the substrate in the cavity portion; and the wiring comprising an external connection terminal portion for connecting to external connection terminals disposed on a surface of the substrate on a side of the cavity opening, an inner connection terminal portion for connecting to a semiconductor chip to be mounted, and a wiring portion in between the external connection terminal portion and the inner connection terminal portion.
A percentage elongation after fracture of the squeeze shapeable wiring construction body is preferred to be not less than 2%. A thickness of the carrier layer composing the squeeze shapeable wiring construction body is preferred to be within a range of 0.010-0.050 mm. A slant angle range of the wall surface of the substrate in the cavity portion is preferred to be from 5xc2x0 to 40xc2x0, and a depth of the cavity portion is preferred to be at least not less than 30% of a thickness of a semiconductor chip to be mounted. The hollow-out process may be performed on the bottom surface of the cavity portion after the cavity portion is formed, and after the hollow-out process, other metal layers may be removed. Performing the hollow-out process while having the other metal layers enable to increase a process accuracy at hollowed out edges.
The above object of the present invention may be accomplished by a fabricating method of a semiconductor chip package substrate having at least one cavity portion for mounting at least one semiconductor chip and wiring, comprising the steps of: a step for making a depth of the cavity portion less than a thickness of a semiconductor chip to be mounted, and a step for hollowing out the cavity portion at the bottom surface, wherein the wiring to the semiconductor chip mounted is cut during the hollow-out process, and the cut edge portion of the wiring reaches a fringe portion of a cavity portion formed by the hollow-out process. A process accuracy at edges of the cavity portion increase.
According to the present invention, a fine pitch wiring corresponding to a connection pitch of the semiconductor chip may be disposed while forming the cavity portion which is capable of mounting the semiconductor chip, and is suitable for an area array type semiconductor package. The semiconductor package utilizing this technology is suitable for CSP (Chip Scale Package), FBGA (Fine Pitch Ball Grid Array), BGA (Ball Grid Array), LGA (Land Grid Array) or the like.

Semiconductor device and method of fabrication thereof


A system for automatically selecting communication frequencies for wireless communication devices (e.g., base unit, access point, and controller) being added to an existing wireless network. The operating frequencies, evaluated signal strength, and loads are used in determining the most suitable operating frequency. This automatic selection process eliminates the problems inherent in manual frequency selection.

The use of wireless networks has become prevalent throughout the modern workplace. For example, retail stores and warehouses may use a wireless local area network (LAN) to track inventory and replenish stock and office environments may use a wireless LAN to share computer peripherals. A wireless LAN offers several advantages over regular LANs. For example, users are not confined to locations previously wired for network access, wireless work stations are relatively easy to link with an existing LAN without the expense of additional cabling or technical support; and wireless LANs provide excellent alternatives for mobile or temporary working environments.
In general there are two types of wireless LANs, independent and infrastructure wireless LANs. The independent, or peer-to-peer, wireless LAN is the simplest configuration and connects a set of personal computers with wireless adapters. Any time two or more wireless adapters are within range of each other, they can set up an independent network. In infrastructure wireless LANs, multiple base stations link the wireless LAN to the wired network and allow users to efficiently share network resources. The base stations not only provide communication with the wired network, but also mediate wireless network traffic in the immediate neighborhood. Both of these network types are discussed extensively in the IEEE 802.11 standard for wireless LANs.
In the majority of applications, wireless LANs are of the infrastructure type. That is, the wireless LAN typically includes a number of fixed base stations, also known as access points, interconnected by a cable medium to form a hardwired network. The hardwired network is often referred to as a system backbone and may include many distinct types of nodes, such as, host computers, mass storage media, and communications ports. Also included in the typical wireless LAN are intermediate base stations which are not directly connected to the hardwired network.
These intermediate base stations, often referred to as wireless base stations, increase the area within which base stations connected to the hardwired network can communicate with mobile terminals. Associated with each base station is a geographical cell. A cell is a geographic area in which a base station has sufficient signal strength to transmit data to and receive data from a mobile terminal with an acceptable error rate. Unless otherwise indicated, the term base station, will hereinafter refer to both base stations hardwired to the network and wireless base stations. Typically, the base station connects to the wired network from a fixed location using standard Ethernet cable, although in some case the base station may function as a repeater and have no direct link to the cable medium. Minimally, the base station receives, buffers, and transmits data between the wireless local area network (WLAN) and the wired network infrastructure. A single base station can support a small group of users and can function within a predetermined range.
In general, end users access the wireless LAN through wireless LAN adapters, which are implemented as PC cards in notebook computers, ISA or PCI cards in desktop computers, or fully integrated devices within hand-held computers. Wireless LAN adapters provide an interface between the client network operating system and the airwaves. The nature of the wireless connection is transparent to the network operating system.
In general operation, when a mobile terminal is powered up, it "associates" with a base station through which the mobile terminal can maintain wireless communication with the network. In order to associate, the mobile terminal must be within the cell range of the base station and the base station must likewise be situated within the effective range of the mobile terminal. Upon association, the mobile unit is effectively linked to the entire LAN via the base station. As the location of the mobile terminal changes, the base station with which the mobile terminal was originally associated may fall outside the range of the mobile terminal. Therefore, the mobile terminal may "de-associate" with the base station it was originally associated to and associate with another base station which is within its communication range. Accordingly, wireless LAN topologies must allow the cells for a given base station to overlap geographically with cells from other base stations to allow seamless transition from one base station to another.
Most wireless LANs, as described above, use spread spectrum technology. Spread spectrum technology is a wideband radio frequency technique developed by the military for use in reliable, secure, mission-critical communication systems. A spread spectrum communication system is one in which the transmitted frequency spectrum or bandwidth is much wider than absolutely necessary. Spread spectrum is designed to trade off bandwidth efficiency for reliability, integrity, and security. That is, more bandwidth is consumed than in the case of narrowband transmission, but the tradeoff produces a signal that is, in effect, louder and thus easier to detect, provided that the receiver knows the parameters of the spread spectrum signal being broadcast. If a receiver is not tuned to the right frequency, a spread spectrum signal looks like background noise.
In practice, there are two types of spread spectrum architectures: frequency hopping (FH) and direct sequence (DS). Both architectures are defined for operation in the 2.4 GHz industrial, scientific, and medical (ISM) frequency band. Each occupies 83 MHz of bandwidth ranging from 2.400 GHz to 2.483 GHz. Wideband frequency modulation is an example of an analog spread spectrum communication system.
In frequency hopping spread spectrum systems the modulation process contains the following two steps: 1) the original message modulates the carrier, thus generating a narrow band signal; 2) the frequency of the carrier is periodically modified (hopped) following a specific spreading code. In frequency hopping spread spectrum systems, the spreading code is a list of frequencies to be used for the carrier signal. The amount of time spent on each hop is known as dwell time. Redundancy is achieved in FHSS systems by the possibility to execute re-transmissions on frequencies (hops) not affected by noise.
Direct sequence is a form of digital spread spectrum. With regard to direct sequence spread spectrum ("DSSS"), the transmission bandwidth required by the baseband modulation of a digital signal is expanded to a wider bandwidth by using a much faster switching rate than used to represent the original bit period. In operation, prior to transmission, each original data bit to be transmitted is converted or coded to a sequence of a "sub bits" often referred to as "chips" (having logic values of zero or one) in accordance with a conversion algorithm. The coding algorithm is usually termed a spreading function. Depending on the spreading function, the original data bit may be converted to a sequence of five, ten, or more chips. The rate of transmission of chips by a transmitter is defined as the "chipping rate."
As previously stated, a spread spectrum communication system transmits chips at a wider signal bandwidth (broadband signal) and a lower signal amplitude than the corresponding original data would have been transmitted at baseband. At the receiver, a despreading function and a demodulator are employed to convert or decode the transmitted chip code sequence back to the original data on baseband. The receiver, of course, must receive the broadband signal at the transmitter chipping rate.
The coding scheme of a spread spectrum communication system utilizes a pseudo-random binary sequence ("PRSB"). In a DSSS system, coding is achieved by converting each original data bit (zero or one) to a predetermined repetitive pseudo noise ("PN") code.
A PN code length refers to a length of the coded sequence (the number of chips) for each original data bit. As noted above, the PN code length effects the processing gain. A longer PN code yields a higher processing gain which results in an increased communication range. The PN code chipping rate refers to the rate at which the chips are transmitted by a transmitter system. A receiver system must receive, demodulate and despread the PN coded chip sequence at the chipping rate utilized by the transmitter system. At a higher chipping, the receiver system is allotted a smaller amount of time to receive, demodulate and despread the chip sequence. As the chipping rate increases so to will the error rate. Thus, a higher chipping rate effectively reduces communication range. Conversely, decreasing the chipping rate increases communication range. The spreading of a digital data signal by the PN code effect overall signal strength (or power) of the data be transmitted or received. However, by spreading a signal, the amplitude at any one point typically will be less than the original (non-spread) signal.
It will be appreciated that increasing the PN code length or decreasing the chipping rate to achieve a longer communication range will result in a slower data transmission rate. Correspondingly, decreasing the PN code length or increasing the chipping rate will increase data transmission rate at a price of reducing communication range.
FIG. 1 schematically illustrates a typical transmitter system 100 of a DSSS system. Original data bits 101 are input to the transmitter system 100. The transmitter system includes a modulator 102, a spreading function 104 and a transmit filter 106. The modulator 102 modulates the data using a well known modulation technique, such as binary phase shift keying ("BPSK"), quadrature phase shift keying (QPSK), and complimentary code keying (CCK). In the case of the BPSK modulation technique, the carrier is transmitted in-phase with the oscillations of an oscillator or 180 degrees out-of-phase with the oscillator depending on whether the transmitted bit is a "0" or a "1". The spreading function 104 converts the modulated original data bits 101 into a PN coded chip sequence, also referred to as spread data. The PN coded chip sequence is transmitted via an antenna so as to represent a transmitted PN coded sequence as shown at 108.
FIG. 1 also illustrates a typical receiver system or assembly, shown generally at 150. The receiver system includes a receive filter 152, a despreading function 154, a bandpass filter 156 and a demodulator 158. The PN coded data 108 is received via an antenna and is filtered by the filter 152. Thereafter, the PN coded data is decoded by a PN code despreading function 1544. The decoded data is then filtered and demodulated by the filter 156 and the demodulator 158 respectively to reconstitute the original data bits 101. In order to receive the transmitted spread data, the receiver system 150 must be tuned to the same predetermined carrier frequency and be set to demodulate a BPSK signal using the same predetermined PN code.
More specifically, to receive a spread spectrum transmission signal, the receiver system must be tuned to the same frequency as the transmitter assembly to receive the data. Furthermore, the receiver assembly must use a demodulation technique which corresponds to the particular modulation techniques used by the transmitter assembly (i.e. same PN code length, same chipping rate, BPSK). Because multiple mobile terminals may communicate with a common base, each device in the cellular network must use the same carrier frequency and modulation technique.
One parameter directly impacted by the practice discussed in the preceding paragraph is "throughput." Throughput or the rate of a system is defined as the amount of data (per second) carried by a system when it is active. As most communications systems are not able to carry data 100% of the time, an additional parameter, throughput is used to measure system performance. In general, throughput is defined, as the average amount of data (per second) carried by the system and is typically measured in bits per second ("bps"). The average is calculated over long periods of time. Accordingly, the throughput of a system is lower than its rate. When looking for the amount of data carried, the overhead introduced by the communication protocol should also be considered. For example, in an Ethernet network, the rate is 10 Mbps, but the throughput is only 3 Mbps to 4 Mbps.
One advantage of DSSS systems over FHSS systems is that DSSS systems are able to transmit data 100% of the time, having a high throughput. For example, systems operating at 11 Mbps over the air carry about 6.36 Mbps of data. FHSS systems can not transmit 100% of the available time. Some time is always spent before and after hopping from one frequency to another for synchronization purposes. During these periods of time, no data is transmitted. Obviously, for the same rate over the air, a FHSS system will have a lower throughput than an equivalent DSSS system.
Based on the IEEE 802.11 specifications, the maximum number of DSSS systems that can be collocated is three. These three collocated systems provide a brut aggregate throughput of 3×11 Mbps=33 Mbps, or a net aggregate throughput of 3×6.36 Mbps=19.08 Mbps. Because of the rigid allocation of sub-bands to systems, collisions between signals generated by collocated systems do not occur, and therefore the aggregate throughput is a linear function of the number of systems. FHSS technology allows the collocation of much more than 3 systems. However, as the band is allocated in a dynamic way among the collocated systems (they use different hopping sequences which are not synchronized), collisions do occur, lowering the actual throughput. The greater the number of collocated systems (base stations or access points), the greater the number of collisions and the lower the actual throughput. For small quantities of base stations or access points, each additional base station or access point brings in almost all its net throughput; the amount of collisions added to the system is not significant. When the number of base stations or access points reaches 15, the amount of collisions generated by additional access points is so high that in total they lower the aggregate throughput. In view of the foregoing, there are some important advantages in using DSSS. It should be appreciated that the terms "access point," "base station" and "controller" are used interchangeably herein. Furthermore it should be understood that in a typical WLAN configuration, an access point (e.g., transceiver device) connects to a wired network from a fixed location using a standard Ethernet cable. Typically, the access point receives, buffers, and transmits data between the wireless network (e.g., WLAN) and a wired network. A single access point can support a small group of users and can function within a range of less than one hundred feet to several hundred feet. End users access the WLAN through wireless LAN adapters, which may be implemented as PC cards in notebook computers, ISA or PCI cards in a desktop computer, or fully integrated devices within hand held computers. The WLAN adapters provide an interface between the client network operating system (NOS) and the airwaves (via an antenna).
One drawback to using DSSS, relates to the selection of an operating frequency when a DSSS access point is added to an existing LAN. In this regard, when an access point is added to an existing LAN, an operating frequency for the access point must be selected. This operating frequency is the one which will be used for communications between the newly added DSSS access point and other communication devices in the network (e.g., mobile units and other access points). In accordance with prior art practice, selection of the operating frequency for the newly added DSSS access point is performed manually. More specifically, a user determines which frequency is most suitable by determining and evaluating a variety of communication parameters, and then operating a computer on the network to select an operating frequency for the access point. This manual selection procedure is inefficient and time consuming. Moreover, it often does not result in an optimized configuration, and in fact, may result in serious errors in the frequency selection which impair communications in the existing LAN. With regard to optimized configurations, it should be recognized that multiple access points in an LAN may be operating on the same frequency. Therefore, it is desirable to allocate frequencies to access points in a manner which evenly distributes the number of access points operating on the same frequency. Moreover, in accordance with IEEE 802.11, some of the operating frequencies are "overlapping," while others are "non-overlapping." It is preferred that "non-overlapping" frequencies be selected, and the number of access points operating on the same frequencies are evenly distributed. It is also desirable for optimized communications, to evaluate the loads associated with each access point, and its corresponding frequencies. Thus, the operating frequency for the new access point can be selected such that it is not a frequency used by an access point with a high load.

System for selecting the operating frequency of a communication device in a wireless network


Hollow fiber drug delivery devices are described. Device can contain structural or solid fibers. Fabric can be formed by fibers being interwoven or joined to each other. All or some of the fibers can be resorbable. Fibers can be subdivided, by deformations or closure points, into numerous compartments that separately deliver drug. Deformations can be located at points of fiber intersection or joining. Different drug or drug formulation can be provided in different places. Fibers can be given appropriate surface treatments or coatings to achieve desired properties such as wetting of pores and surfaces. Different release characteristics in different directions can be achieved. The hollow fibers can contain solid particles of drug, and can contain gel. Possible applications include hernia meshes, pouches, sutures, catheters, wound dressings, stents, nerve regrowth guides, refillable/drainable devices, and devices that deliver drug to lymphatic flow.

Various technologies exist for the controlled delivery of drugs to patients. For example, for implanted fabrics or meshes, the solid fibers comprising the fabric or mesh are sometimes coated with small molecular drugs or biologics prior to implantation. However, the type, class and amount of the drug or biologic that can be introduced in this manner is somewhat limited, and can be depleted quickly after implantation. In many applications such drug delivery systems are not suitable for long-term release therapies or some other therapies.
In another approach, drugs can be blended or impregnated into the fibers of a degradable (resorbable) fabric or mesh, such that the drugs would be released over a time, and the material of which the fibers are made is then absorbed into the body. This method works but can be limited to pharmaceuticals or biologics that can tolerate elevated temperatures, or exposure to solvents, and can remain active after harsh processing conditions needed to create the drug delivery device.
Accordingly, it is desirable to have greater ability and flexibility to control the release rate, drug quantity, location, and other parameters of the drug delivery system and implants. It would also be desirable to combine the drug delivery with another function such as structure of the device that incorporates the drug to be delivered. It would also be highly desirable to employ drug delivery systems such that sensitive drugs or biologics can be loaded or incorporated into devices without degrading such drugs during preparation, processing or manufacturing.
In clinical practice, implanted surgical meshes such as hernia repair meshes or other constructs used in reconstruction procedures can become infected with bacteria in the form of biofilm. A major reason that infections associated with prosthetic meshes cannot be resolved using systemic antibiotic chemotherapy, and therefore require removal of the prosthetic mesh or device, is because pathogens form bacterial biofilms directly on the meshes themselves, and biofilm bacteria are highly resistant to antibiotics, requiring therapeutic concentrations thousands of times the minimum biocidal concentration (MBC) as determined by conventional antibiogram. These antibiotic concentrations far exceed those achievable by systemic administration. Weavable and flexible filament that can provide the mechanical strength needed for the implantable device while at the same time eluting antibiotics and antimicrobials to prevent the formation of biofilm, which is extremely desirable for use in patients with high risk of infection. Another important consideration in the design of anti-biofilm surgical meshes and sutures for soft tissue repair is that: 1) they target a wide range of Gram positive and Gram negative bacteria since these types of infections are often polymicrobial, and 2) they have the potential to specifically target biofilm formation. Ideally, such a material would provide prophylactic protection preventing biofilm formation on the device for a period of weeks to months, which appears from the clinical data to be the critical "at-risk" period.
Known implantable drug delivery devices mainly operate using diffusion as the drug release mechanism. This limits the types of therapies to which they are applicable, as determined by the release characteristics that they are able to provide.

Implants and constructs including hollow fibers


A communication terminal has a user interface having a keypad and display means, said key pad is included in a releasable housing part assembly, a processor controlling the terminal in dependence of the operation of the user interface, and identification means included in said housing part assembly for identifying the housing part assembly. The processor controls the display means in dependence of the identified housing part assembly.

During recent years it has become still more popular to exchange covers of phones in order to change the aesthetic appearance of the phone. Basically this started with the phone sold under the trade name Nokia 2110™. Later on the phone sold under the trade names Nokia 5110™ and Nokia 3210™.

Communication terminal having exchangeable parts


Implementations generally relate to determining tool handedness for surgical videos. In some implementations, a method includes receiving at least one image frame of a plurality of image frames. The method further includes detecting one or more objects in the at least one image frame. The method further includes classifying the one or more objects into one or more tool classifications, where the one or more objects are tools. The method further includes determining, for each tool, if the tool is assistive or non-assistive. The method further includes determining, for each tool, a handedness of the tool.

Computer-assisted surgery uses computer technology for guiding or performing medical procedures such as procedures involving endoscopy, laparoscopy, etc. During surgery, a surgeon may need to use various tools to perform surgery. A camera and monitor can help a surgeon to manipulate multiple surgical tools using robotic arms. However, it can be difficult to view surgical tools well on a monitor during surgery.

This patent is subject to a terminal disclaimer.

Tool handedness determination for surgical videos


An apparatus for blocking a medium flow passage in a spray head has a blocking element in the passage that, when unbroken, blocks the passage of medium from a first side having a first pressure to a second side having a second pressure. A supporting element is on that side of the blocking element where the pressure is lower, the supporting element being movable between a first position where the supporting element supports the blocking element so that it cannot be ruptured and a second position where the supporting element does not so support the blocking element.

The present invention relates to an apparatus for blocking a medium flow passage in a spray head. The apparatus comprises a blocking element, such as a burst disk, arranged in the passage. When unbroken, the blocking element blocks the passage of medium flow from a first side of the blocking element to a second side of the blocking element. On the first side of the blocking element a first pressure prevails in the passage, while on the second side of the blocking element a second pressure prevails in the passage. The blocking element has been arranged to be ruptured so as to form a passage for the medium through the blocking element when the pressure difference between the first and the second sides of the blocking element reaches a preset value.
In fire extinguishing technology, solutions are also known in which the flow passage of an extinguishing medium is provided with an element rupturable by the prevailing pressure (burst disk, rupture disk), placed between a liquid source and a spraying nozzle to block the passage. These are ruptured when the pressure difference in the passage on different sides of the burst disk exceeds a given value, which is characteristic to each burst disk. A solution of this type is described e.g. in the publication Fire Protection Handbook, 18th Edition, 1997, pages 6-200. Specification DE 19948324 discloses a corresponding solution. In prior-art solutions, the burst disk is so designed that it is bound to be ruptured when the pressure difference increases sufficiently. Therefore, incidental pressure variations occurring in the piping e.g. due to a malfunction may cause a rupture of the burst disk, which again results in significant extra costs. If the burst disk is so designed that it will not be ruptured until the pressure difference has reached a very high value, this may jeopardize reliable operation of the system in a fire situation. Solutions have therefore been developed in which the burst disk is ruptured by using separate devices to pierce the burst disk. These have not always been satisfactory in operation or they have been complicated and required energy from outside in order to work.
On the other hand, prior-art devices known in fire extinguishing technology include sprinkler heads provided with a valve element which in a non-activated state blocks the liquid flow passage and, when the sprinkler is activated upon being triggered, e.g. when a heat activated ampoule is broken, moves into a position where the extinguishing medium can flow into one or more nozzles. These solutions use dynamic seals, such as 0-rings, to seal the space between the valve element and the flow passage wall In the non-activated state. A sprinkler head of this type, which uses ring-like seals, is disclosed in U.S. Pat. No. 5,967,239 (Sprakel, et al.). In recent times there has appeared a need to avoid the use of dynamic seals in spray heads used for fire extinguishing purposes. In addition, the clearances between the valve element or shaft and the sprinkler body typically have to be made very small.
The object of the present invention is to achieve a completely new type of solution in conjunction with blocking elements to ensure their reliable operation. On the other hand, a second object is to achieve a compact solution in conjunction with spray heads to avoid the use of dynamic seals.

Apparatus for blocking a medium flow passage in a spray head, and spray head


A wall mounted-type microwave oven provided with a hood having an inlet port with an improved structure, thus effectively drawing exhaust gases and food odors produced from a plurality of gas burners placed below the hood. The wall mounted-type microwave oven includes a cabinet and a hood. The cabinet has, at predetermined portions thereof, an exhaust passage and an exhaust fan. The hood is mounted to a bottom portion of the cabinet, and has an inlet port to communicate with the exhaust passage. The inlet port is formed so that a width of an end of the inlet port near to the exhaust passage is less than a width of an end of the inlet port farther from the exhaust passage. Thus, the inlet port is formed so that an area of a portion of the inlet port on which a weaker suction force of the exhaust fan acts is larger than an area of a portion of the inlet port on which a stronger suction force of the exhaust fan acts.

1. Field of the Invention
The present invention relates to wall mounted-type microwave ovens, and more particularly, to a wall mounted-type microwave oven provided with a hood having an inlet port with an improved structure, thus effectively drawing exhaust gases and food odors produced from a plurality of gas burners placed below the hood.
2. Description of the Related Art
Generally, a wall mounted-type microwave oven is mounted to a wall of a kitchen above a plurality of gas burners. The wall mounted-type microwave oven collaterally serves to exhaust gases, fumes, and food odors produced from the gas burners, which are positioned under the microwave oven, in addition to cooking food using high-frequency electromagnetic waves.
Similar to a general type microwave oven, the wall mounted-type microwave oven includes a cabinet to define an external appearance thereof. The cabinet is partitioned into a cooking cavity and a machine room, and the food to be cooked is disposed in the cooking cavity. An exhaust passage is defined between an outside of the cooking cavity and the cabinet. Further, an exhaust fan is provided to an upper portion of the exhaust passage to draw exhaust gases and food odors produced from the plurality of gas burners into the exhaust passage, and to discharge the exhaust gases and the food odors to the outside of the wall mounted-type microwave oven.
Further, a hood having an inlet port is mounted to a bottom portion of the cabinet. The inlet port of the hood communicates with the exhaust passage so that the exhaust gases and the food odors produced from the plurality of gas burners flow through the inlet port into the exhaust passage.
However, according to the conventional wall mounted-type microwave oven, the exhaust passage is provided at a side of the cabinet and the inlet port through which exhaust gases and food odors are drawn into the exhaust passage is constructed to have a constant width. Thus, a stronger suction force of the exhaust fan acts on the gas burners placed near the exhaust passage in comparison to gas burners placed far from the exhaust passage. Therefore, exhaust gases produced from gas burners placed near the exhaust passage are smoothly drawn into the exhaust passage, whereas exhaust gases produced from gas burners placed far from the exhaust passage are not smoothly drawn into the exhaust passage.
Therefore, the conventional wall mounted-type microwave oven presents a problem because the wall mounted-type microwave oven does not effectively draw and discharge exhaust gases produced from all gas burners placed below the hood.


A single bat carrier that can be used conveniently in a baseball or softball game to carry and transport a user's bat is disclosed in the present invention. The single bat carrier comprises a bat bag made of Denier nylon with a closed bottom end, a heavy-duty plastic tube inserted into the bat bag to prevent any damage to the bat, a top end cap assembly with a hinge means that fastens to the plastic tube to cover the top opening, a zipper for connecting the end cap and the nylon bat bag, another end cap glued to the bottom side of the plastic tube to hold the bat, a plurality of nylon straps for carrying purposes and for holding a baseball or softball glove, and a snap hook for fastening the single bat carrier to a fence.

The present invention relates generally to the field of sports bags, and more particularly to a baseball or softball bat tube and carrier that can be used to conveniently carry, transport and protect a bat.
The games of baseball and softball are well known in the United States and many other parts of the world, and enjoy continued and increasing popularity. These sports principally require the use of a bat, a ball, and a glove for each player as basic equipment. It is therefore common for players to own an assortment of bats, gloves, balls and other related accessories. Additionally, a team coach may carry a number of bats and other related baseball or softball equipment for an entire team.
Modern bats are hollow and designed to be both lightweight and resilient when striking a baseball or softball. However, they are prone to damage when struck by a hard materials such as metal or stone, or when subjected to lateral pressure, which may cause creases in, or bend the bat. Because such hazards are common around playing fields, it is important to store bats that are not in play in a secure, protective environment.
A variety of bat and other sports related bags exist in the market, and have been disclosed in the art. For example, U.S. Pat. No. 5,695,067 to Harvey discloses a storage and tote bag for baseball and softball bats and balls. It is a soft, zippered bag that stores bats by allowing them to lie flat along the bag's length and stores balls in the bottom of the bag.
U.S. Pub. No. 20040262178 to Speck discloses a baseball equipment bag having an elongated bag portion of flexible material and a substantially planar interior shelf within the elongated bag portion. The equipment bag includes a bat compartment that allows a bat to be accessed from either of two openings.
Further, in U.S. Pat. No. 6,168,016 to Lawson, a utility bag for storing equipment for a baseball/softball team is disclosed. The bag is constructed to be strapped to and transported on a golf cart. A bat bag for storing bats is attached to the outside surface of the utility bag, and contains a detachment means.
There are, however, a variety of problems associated with such equipment bags. One such problem is that they are typically meant for carrying multiple bats, making them bulky, heavy and make transporting the bats more difficult. They also typically consist merely of a nylon bag sewed together conferring little protection for the equipment contained inside.
Some new bags available in the market today are composed of metal for protection. However, these types of bags are problematic as well. They are usually expensive, too heavy and bulky to even carry a single bat, and tend to dent easily if bumped against any hard surface.
The present invention is designed to overcome the shortcomings known in the current state of the art, and provide a single baseball or softball bat carrier that can be used conveniently to carry, transport and protect a user's bat.
It is one object of the present invention to provide a single baseball or softball bat carrier that is lightweight and easy to carry.
Another object of the present invention is to provide a single baseball or softball bat carrier that is of slim and compact design.
A further object of the present invention is to provide a single baseball or softball bat carrier that is of heavy-duty construction, providing an interior tube for maximum protection of the contents, and is weather resistant.
These and other objects will become apparent from the accompanying drawings and the following description.


A spring contact structure (10) and an electronic device using same are provided. The spring contact structure is configured for releasing electrostatic charges of the electronic device, and includes a fixing portion (12), a clamping portion (14) and a grounding portion (16). The clamping portion is configured for electrically connecting to a substrate (30) of the electronic device, and includes a first clamp arm (142) and a second clamp arm (144) extending from opposite sides of the fixing portion. The second clamp arm is disposed over the fixing portion and the first clamp arm to clamp the substrate between the first and second clamp arms. The grounding portion extends from the fixing portion, and is configured for electrically connecting to a grounding unit (40) of the electronic device.

1. Technical Field
The present invention relates to a conductive contact, particularly to a spring contact structure and an electronic device equipped with the spring contact structure.
2. Description of the Related Art
Electronic products often are equipped with spring contact structures. The spring contact structure is for providing electrical conductivity for conductive components of electronic products. For example, a spring contact structure is provided between electronic components and a circuit board to electrically connect the electrical components to the circuit board. Spring contact structures may also provide ground connection between two circuit boards or between a circuit board and electronic components arranged thereon to eliminate the potential difference therebetween. In addition, for some electronic products incorporating a metallic shielding can for shielding the electronic components arranged on a circuit board from electromagnetic interference (EMI), the spring contact structures are equipped to provide ground connection between the metallic shielding can and the circuit board. In this way, electrostatic charges generated on the metallic shielding can could be released to ground of the circuit board by the spring contact structures to protect the electronic product from damage of electrostatic discharge (ESD).
Generally, spring contact structures are C-shaped metal sheets. In use, the end pieces of the spring contact structure electrically connect to the electronic component and the ground of the circuit board, respectively. Usually, the spring contact structure provides only one contact end piece to connect with the circuit board, which means there is only one connect point for electrical continuity. Therefore, there is a risk that the electronic product may be damaged by ESD if the electrostatic charges cannot be timely released to ground.
Therefore, there is room for improvement with the art.

Spring contact structure and electronic device using same


An ultra cycling nitride read only memory (NROM) device is coupled to a NROM array such that both bits of the ultra cycling NROM device will be erased when all NROM devices of the NROM array are erased. The ultra cycling NROM device is then programmed at its right bit. A threshold voltage difference will be obtained for the ultra cycling NROM device for the un-programmed left bit. Next, a cycling number is obtained based on the threshold voltage difference for the ultra cycling NROM device. A threshold voltage shift can be found based on the cycling number for the NROM array. Finally, an erase voltage will be calculated according to the threshold voltage shift for the NROM array. If the NROM array is programmed again, the erase voltage will be applied to un-programmed NROM devices of the NROM array to further reduce the threshold voltages.

1. Field of the Invention
The present invention relates generally to a flash memory device, and more particularly, to a system and a method for preventing read margin degradation for a nitride read only memory array.
2. Description of the Related Art
Nitride Read Only Memory (NROM) devices are widely used in the semiconductor industry. As is well known in the art, a NROM device stores charges at both ends of a composite oxide-nitride-oxide (ONO) layer, thus being capable of two bits operation. When a bit of the NROM device is programmed with a charge, the threshold voltage for that bit of the NROM device will be increased. A programmed bit of the NROM device represents a logic "0," while an un-programmed or erased bit of the NROM device represents a logic "1." The charge stored at one bit of the NROM device will affect the threshold voltage of the other bit, which is the second bit effect of the NROM device.
The charge retention ability of a NROM device is affected by both the cycling numbers and the aging of the NROM device. A cycling of a NROM device includes a program operation and an erase operation. As the number of cyclings for a NROM device increases, the ONO layer of the NROM device will suffer damage, thus resulting in charge losses and the decrease of the threshold voltage for the NROM device. The aging of a NROM device contributes to the charge loss as well. Therefore, the aging of a NROM device will also decrease its threshold voltage.
FIG. 1 shows the threshold voltage Vt distributions for a NROM array 100 after 10,000 cyclings and 150° C. baking for 20 hours. The high Vt distribution 110 represents the threshold voltage distribution of the NROM array 100 at a programmed state after 10,000 cyclings, whereas the low Vt distribution 130 represents the threshold voltage distribution of the NROM array 100 at an erased state after 10,000 cyclings. Each distribution has its high bond and low bond. The threshold voltage difference between the high Vt distribution 110 at its low bond and the low Vt distribution 130 at its high bond forms the read margin 150, which is the read margin for the NROM array 100 after 10,000 cyclings. No aging effect is considered for the high Vt distribution 110 and the low Vt distribution 130 of the NROM array 100.
In order to demonstrate the aging effect for the NROM array 100, after 10,000 cyclings, the NROM array 100 is baked at 150° C. for 20 hours, which is equivalent to the aging of the NROM array 100 at 25° C. for ten years. The high Vt distribution 120 represents the threshold voltage distribution for the NROM array 100 at a programmed state after 150° C. baking for 20 hours and 10,000 cyclings, whereas the low Vt distribution 140 represents the threshold voltage distribution for the NROM array 100 at an erased state after 150° C. baking for 20 hours and 10,000 cyclings. As shown, the threshold voltages of the NROM array at both the programmed state and the erase state are decreased due to the aging effect. The threshold voltage difference between the low bonds of the high Vt distributions 110 and 120 is ΔPV, while the threshold voltage difference between the high bonds of the low Vt distributions 130 and 140 is ΔEV. The threshold voltage difference between the high Vt distribution 120 at its low bond and the low Vt distribution 140 at its high bond forms the read margin 160, which is the degraded read margin for the NROM array 100 after the aging effect and 10,000 cyclings.
As indicated in FIG. 1, the read margin 160 is much narrower than the read margin 150 due to the aging effect. A narrow read margin could cause errors in a read operation for the NROM array 100. As shown, ΔPV, i.e., the decrease of the threshold voltage of the NROM array 100 at a programmed state after the NROM array 100 is affected by the aging, is the cause for the read margin degradation for the NROM array 100.
In view of the foregoing, there is a need for a system and a method that can prevent read margin degradation for a NROM array that is affected by the aging.

System and method for preventing read margin degradation for a memory array


A vibratory apparatus comprises an eccentric mass disposed within a housing. A shaft and bushing are received by the eccentric mass and couple the eccentric mass to a crankshaft. An internal conduit extends longitudinally within the shaft. Input and output conduits each communicate with the internal conduit to allow a lubricant to flow through the shaft. A bore extends radially through the bushing. Lubricant flowing through the shaft may further flow through the bore and form a lubricating layer between the bushing and the eccentric mass.

This invention relates to orbiting mass vibrators, and in particular, to orbiting mass vibrators adapted for use on a rotary-vibratory drills or sonic drills.
In conventional orbiting mass vibrators adapted for use on rotary-vibratory drills, vibratory energy is generated by a pair of counter-rotating eccentric masses rotating along confined orbital paths within a housing. The eccentric masses are confined to the orbital paths by a cylindrical bore in the housing. Each eccentric mass is coupled to the housing and delivers vibratory forces to the housing. The housing in turn provides the vibratory output to a drill bit. However, if the eccentric masses and crankshafts are not properly aligned, excess vibratory forces may develop in the crankshafts. These excess vibratory forces may ultimately cause damage to the rotary-vibratory apparatus. It is therefore an objective of the invention to provide a self compensating mechanism which allows the eccentric masses and crankshafts to remain decoupled during the operation of the rotary-vibratory apparatus.

Vibratory apparatus for a rotary-vibratory drill


An amplifier cell apparatus has an RF input node, a first power transistor in communication with the input node through a first input impedance matching network, a second power transistor in communication with the input node through a second input impedance matching network, and an RF output node in communication with the first and second power transistors through a single output impedance matching network so that the first and second input impedance matching networks are disposed on an RF input side of the amplifier cell.

1. Field of the Invention
The invention relates to power amplifiers, and more particularly to radio frequency (RF) power amplifiers.
2. Description of the Related Art
The rapid development of E-band and W-band communications, radar, and imaging systems, has been facilitated by the use of power amplifier cell arrays developed using indium phosphide (InP) and silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technologies achieving high current and low voltage solutions. A gallium nitride (GaN) high electron mobility transistor (HEMT) power amplifier cell (high voltage, low current technology) for use in such arrays may utilize thru-substrate reactive microstrip for power combining with adjacent cells. The RF matching networks may share the same RF matching structure as that used for DC current in such arrays.
Unfortunately, as such topologies are used for ever-higher frequency and output power applications, usable bandwidth in such power amplifier cell arrays tends to decrease. A need continues to exist to provide for high frequency and high power RF power amplifiers while maintaining or extending usable bandwidth.

Power amplifier having separate interconnects for DC bias and RF matching networks


A flame-retardant synthetic resin composition containing (A) a synthetic resin and (B) a compound having a 3-halogeno-2-hydroxypropyl group, which shows excellent thermal stability during molding and having good light resistance, is disclosed. A flame retardant comprising a compound having a 3-halogeno-2-hydroxypropyl group is also disclosed.

There have conventionally been known techniques for imparting flame retardancy to synthetic resins such as styrene resins and polyester resins. For example, JP-A-50-27843 (The term "JP-A" as used herein means an "unexamined published Japanese patent application".) discloses an expedient of incorporating a halogenated bisphenol A epoxy resin, as a flame retardant, having low volatility and excellent non-bleeding properties, heat resistance, and other properties and, according to need, further incorporating antimony trioxide or the like as a flame retardant aid. JP-A-62-4737 discloses an expedient of modifying an epoxy resin for use as a flame retardant by blocking the epoxy groups in the epoxy resin with a halogenated phenol such as tribromophenol.
However, the incorporation of a halogenated bisphenol A epoxy resin as disclosed in JP-A-50-27843 has had a problem that the thermal stability of the synthetic resin whose flame retardancy should be improved is significantly impaired by the epoxy resin. Illustratively stated, when the epoxy resin-incorporated synthetic resin composition is kneaded in an extruder and molded with an injection molding machine, epoxy groups in the epoxy resin undergo a polymerization reaction according to the heat hysteresis applied to the molten resin composition and, as a result, the epoxy resin gels, causing the composition to show poor flowability during molding, suffer discoloration, and come to contain aggregates resulting from gelation.
On the other hand, the flame retardant disclosed in JP-A-62-4737 has had a defect that although the proposed epoxy resin has eliminated the gelation problem, it impairs the light resistance of synthetic resins more than unmodified halogenated bisphenol A epoxy resins in which the epoxy groups are unblocked.
Since light resistance is an important requirement particularly for styrene resins in view of their actual uses, there has been an intense desire to solve the problem that flame-retardant synthetic resins excellent in both thermal stability and light resistance have been unable to be obtained.

Flame-retardant synthetic resin composition and flame retardant


The present invention relates to a molding material for OA machine parts, wherein such material comprises a resin combination of 60 to 98 parts by weight of a polyphenylene ether-based resin, 2 to 40 parts by weight of a thermoplastic elastomer, and 1 to 50 parts by weight of a flame retardant, such that the resin composition has a bending modulus of not less than 1500 MPa as measured at 23xc2x0 C. according to ASTM D790, a damping ratio of not less than 1.0% at 23xc2x0 C., and a thermal deformation temperature of not less than 100xc2x0 C. as measured according to ASTM D648 under 18.6 kg/cm2 load, and wherein the product of the bending modulus and the damping ratio is not less than 10,000 MPa*%.

The present invention relates to a molding material for OA machine parts with improved vibration-damping properties, particularly it relates to such a molding material comprising a polyphenylene ether-based or polycarbonate-based resin having high mechanical strength, heat resistance and dimensional accuracy.
Since polyphenylene ether-based resins and polycarbonate-based resins have many excellent properties such as high mechanical strength, heat resistance, dimensional stability and flame retardancy, they are popularly used as material of various commercial products in many fields of industry, such as typically electronic parts, electrical apparatus and automobile parts.
Recently, most remarkably, these polyphenylene ether-based and polycarbonate-based resins are used instead of the conventional metals and thermosetting resins, as material of the business machine parts, especially chassis parts of such office machines as copiers and facsimiles, or the chassis parts or trays of the disc drives such as CD-ROM drive, DVD, FDD, HDD, etc., used in personal computers. This owes to the excellent properties such as high mechanical strength, heat resistance, dimensional accuracy and flame retardancy of the polyphenylene ether-based and polycarbonate-based resins. In applications where high rigidity is required, the reinforced polyphenylene ether or polycarbonate resins containing inorganic fillers are used. Development of these resin materials is also answering to the request for smaller size and thickness of the products in recent years.
Lately, however, there has arisen the problem of vibration incidental to the operational speed-up of the OA machines. Vibrations generated at their source, such as motor in a device, are transmitted to the resin-made parts, especially chassis parts, to let them vibrate, which is liable to result in causing blurring of the image or difficulty in reading data. For instance, the increase of processing speed in the case of copying machines or the increase of rotation speed in the case of disc drives such as CD-ROM drive has boosted the generated frequency to a very high level, such as 1,000 Hz in some cases, in contrast with the frequency of up to about 200 Hz in the conventional devices.
Because of such elevation of the output frequency, it has now become difficult to hold down vibrations of the chassis parts, in which it has been possible to overcome by increasing thickness or by proper designing of the rib structure in the conventional products. In the resin material, efforts have been made to increase rigidity by blending a greater amount of inorganic filler to raise the resonance frequency, so that the resonance frequency may be left out of the range of generated frequency. However, there is a limitation due to excessive elevation of the generated frequency. As another antivibration means from the resin material, it is suggested to use a material which is capable of absorbing vibrations. However, such vibration-absorbing materials are poor in rigidity and heat resistance, and impracticable for the OA machine parts.
Further, in a resin molding material for OA machine parts, excellent flame-retardant property is required. Usually, the flame-retardant property is evaluated by UL94 test. In a resin molding material for OA machine parts, the flammability of V-0, V-1 or V-2 rank according to UL94 vertical combustion test is required. However, it is difficult for a resin molding material for OA machine parts to satisfy the excellent vibration damping properties and excellent flame-retardant property, simultaneously.
Under these circumstances, there has been desired development of a resin molding material having improved vibration damping properties and flame-retardant property while maintaining high mechanical strength and heat resistance required for the OA machine parts.
As a result of the present inventors"" earnest studies to solve the above problem, it has been found that a molding material comprising a polyphenylene ether-based or polycarbonate-based resin composition having a specific modulus of elasticity and damping ratio, is suited for the OA machine parts. The present invention has been attained on the basis of the above finding.
An object of the present invention is to provide a molding material for OA machine parts which has excellent vibration damping properties and flame-retardant property, by using a polyphenylene ether-based or polycarbonate-based resin with high mechanical strength, heat resistance and dimensional accuracy.
To attain the above aim, in an aspect of the present invention, there is provided a molding material for OA machine parts comprising a resin composition comprising:
(1) 60 to 98 parts by weight of a polyphenylene ether-based resin comprising 10 to 100% by weight of a polyphenylene ether resin and 0 to 90% by weight of a styrene-based resin, or a polycarbonate-based resin comprising 50 to 100% by weight of a polycarbonate resin and 0 to 50% by weight of a styrene-based resin;
(2) 2 to 40 parts by weight of a thermoplastic elastomer which is a conjugated diene rubber having not less than 50% by weight of 1,2-vinyl structure, 3,4-vinyl structure or mixture thereof, a styrene-conjugated diene block copolymer having not less than 50% by weight of 1,2-vinyl structure, 3i4-vinyl structure or mixture thereof, or a hydrogenated product thereof; and
(3) 1 to 50 parts by weight of a flame retardant,
the total amount of (1) polyphenylene ether-based or polycarbonate-based resin and (2) thermoplastic elastomer being 100 parts by weight,
said resin composition having bending modulus of not less than 1500 MPa as measured at 23xc2x0 C. according to ASTM4 D790, a damping ratio of not less than 1.0% at 23xc2x0 C., and a thermal deformation temperature of not less than 100xc2x0 C. as measured according to ASTM D648 under 18.6 kg/cm2 load,, and
the product of the bending modulus and the damping ratio being not less than 10,000 MPa.%.

Molding material for OA machine parts with improved vibration damping properties


A shield structure for information technology equipments includes an opening part provided in a portion of the shield structure and a lid covering the opening part. A signal ground line is provided on a printed circuit board accommodated in the enclosure. An electric connection material extends between the lid and the signal ground line of the printed circuit board and has at least a surface formed by an electrically conductive material. The electric connection material is in contact with the signal ground line of the printed circuit board.

1. Field of the Invention
The present invention generally relates to information technology equipments and, more particularly, to a shield structure for information technology equipments, such as a notebook-type personal computer, provided with an opening for replacing a memory module.
2. Description of the Related Art
In recent years, it has become indispensable to take countermeasures against electromagnetic wave interference (EMI) or countermeasures against electrostatic discharge (ESD) with respect to information technology equipments such as a desktop-type personal computer (desktop PC), a notebook-type personal computer (note PC), a printer, a facsimile, etc. In EMC, especially, regulation for electromagnetic interference (EMI) has been progressed, and each country independently regulates its own standard or specification. Manufacturers of information technology equipments cannot sell or export their products unless they clear standards with respect to the EMI regulations. As standards with respect to the EMI regulations, there are, for example, Agreement of VCCI (Voluntary Control Council for Interference by Information Technology Equipment) in Japan, and the FCC rules and regulations in the United States.
As an international standard used as the basis of the rules regarding EMI regulations, there is a specification which is set by International Special Committee on Radio Interference (CISPR). It is the present status that each country establishes a specification based on the CISPR specification. Thus, if the CISPR specification is cleared, a rule of each country is almost cleared.
It is general in a note PC, which is one of information technology equipments, to apply a metal plate or a metal sheet or apply metal-plating on a backside of an enclosure so that electromagnetic waves do not leak from inside of the enclosure. By covering an entire surface of the enclosure, the equipment can have a structure in which electromagnetic wave do not leak outside. However, it is difficult to cover an entire surface of an enclosure. Especially, an opening part is formed on an enclosure at a portion provided with a connector for connection with external equipments, and electromagnetic waves may leak through the opening part.
Accordingly, as countermeasures against EMI, it is suggested to suppress such leakage of electromagnetic waves by attaching a metal made or metal-plated lid to an opening part of a shield structure and electrically connecting a metal portion of the lid to a ground potential portion of the enclosure (for example, refer to Patent Document 1).
Patent Document 1: Japanese Laid-Open Patent No. 2000-151132
In a personal computer or the like, in order to incorporate an expansion memory module into a printed circuit board inside an enclosure, usually, an opening for taking a memory module in and out is provided to the enclosure. The opening is closed by a metal made or metal-plated lid. However, it is difficult to completely cover a mating portion between a rim of the opening and an edge of the lid, and, thus, the EMI requirements may not be cleared due to leakage of electromagnetic waves from the mating portion.
Especially, in many cases in a note PC, a so-called butterfly type connection structure, which connects two memories to a connector part face-to-face, is used. According to the butterfly type connection structure, signal lines to the memories extend between the two memories. Since exchange of signals is performed frequently through the signal lines during operation of a CPU, the signal lines are source of generating electromagnetic waves.
Accordingly, if the butterfly type connection structure is used as an expandable and replaceable memory connection structure, there is a problem in that the EMI requirements cannot be cleared since an opening part of an enclosure is located near the butterfly type connection structure and leakage of electromagnetic waves through a periphery of the opening part become remarkable.
Moreover, an operation clock of CPUs is increased to a high frequency more and more, and with such an increase, an electromagnetic wave generated from the signal lines to the memories becomes a high-frequency. Thus, an electromagnetic wave tends to leak even through a small gap of shield.
Conventionally, if an amount of leakage of electromagnetic waves through an opening part for memory, a plurality of electromagnetic wave absorption sheet are applied to a lid, and, besides, an electrically conductive gasket or the like for electrically connecting a peripheral part of the lid and a periphery of the opening part is provided, as countermeasures against EMI. Such countermeasures against EMI requires costs of parts such as an electromagnetic wave absorption sheet and electrically conductive gasket and a process cost for operations to attach such a part, and, thus, there is a problem in that an increase in a manufacturing cost of a product itself is invited.

Shield structure for information technology equipments


A device for increasing the range of motion of a patient's knee joint generally includes a frame, a lever member pivotally coupled to the frame at a first location, and an actuator pivotally coupled to the frame at a second location. The frame supports the patient in a manner that allows motion of the patient's knee joint, and the lever member bears against a portion of the patient's body below the knee joint. The actuator is also pivotally coupled to the lever member. When operated by a controller, the actuator generates a translational input that rotates the lever member relative to the frame and thereby stretches the patient's knee joint in a desired direction.

Many types of injuries and surgeries can result in an individual losing some range of motion in his or her knee joint. For example, patients who undergo surgery to treat anterior or posterior cruciate ligament reconstructions, meniscus tears, femur fractures, tibia plateau fractures, or other injuries associated with the knee joint or nearby areas of the body often experience some degree of arthrofibrosis (joint stiffness). Indeed, arthrobrosis is one of the leading complications of knee surgery. This undesirable condition results from the formation of extensive, internal scar tissue and other factors that limit motion of the patient's knee joint. Arthrofibrosis may involve the loss of flexion (bending movements), the loss of extension (straightening movements), or both.
To treat arthrofibrosis, a patient must typically follow a specially planned, intensive protocol of serial stretching and overpressure therapy. This protocol is primarily carried out through hands-on treatment from a physical therapist in a clinic. Although physical therapy may help the patient regain partial or full range-of-motion, the closely-supervised treatment can be relatively expensive and inconvenient for the patient. Several physical therapy sessions are often required each week to treat arthrofibrosis, which means that the patient must adjust his or her schedule accordingly.
As a result, some orthopedic surgeons recommend using in-home mechanical therapy devices as an alternative to (or to decrease reliance on) hands-on physical therapy. Several mechanical devices have been developed to stretch a patient's knee joint and thereby urge increased motion. Current devices, however, leave significant room for improvement.
For example, many of the current in-home mechanical therapy devices are complex to operate, involve numerous parts, or have limited effectiveness. These devices may require the patient to actuate levers, stabilize components, or perform other functions while attempting to stretch his or her knee joint, which may be a painful process that requires concentration itself. Moreover, many of the in-home mechanical devices are not designed to stretch the knee joint in both flexion and extension. The use and storage of two separate devices to treat joint stiffness can be cumbersome.
Although automated continuous passive motion (CPM) machines exist for more effectively stretching knee joints and other areas of the body, these machines are not designed for in-home use. In particular, these machines typically include a mechanical leg cradle that bends and straightens the patient's knee while the patient sits or lies down on a supporting surface. Machines including the supporting surface occupy a significant amount of space and are intended for facilities dedicated to treatment (physical therapy facilities, etc.), which have the space to accommodate such machines. The machines are also relatively expensive because of their complexity.
For at least these reasons, a mechanical therapy device that effectively stretches a patient's knee joint and that is suitable for in-home use would be highly desirable.

Device and method for knee joint rehabilitation


Photovoltaic systems with managed output and methods for managing variability of output from photovoltaic systems are described. A system includes a photovoltaic module configured to receive and convert solar energy to DC power. The system also includes a sensor configured to detect a future change in solar energy to be received by the photovoltaic module. The system further includes a power conditioning unit coupled with the photovoltaic module and the sensor.

Common types of photovoltaic deployment include off-grid and on-grid systems. Off-grid systems are typically small (e.g., 10 s of kilowatts at most) and tied closely to an energy storage system such as a system of deep-cycle lead acid batteries or, in some cases, to a fueled gen-set. In an off-grid configuration, the energy stored in the battery acts as a buffer between energy production and demand. As such, short-term variability in the solar resource may not be an issue. On-grid systems, by contrast, may be quite large, with systems up to the 100 s of megawatts. To date, sizing of on-grid systems may be such that existing methods of handling load variability (e.g., by provision of ancillary services from generators on the grid) have been sufficient to ensure stability of the grid.
However, with advances in photovoltaic system technology, ever larger systems are being proposed and actually installed for use. Such larger systems may pose challenges for power management in at least two end markets, e.g., in island- or micro-grid systems or in very large photovoltaic plants integrated onto large grids. In either case, there may be restrictions on the maximum allowable ramp rates (both "up" and "down") that are permitted in order to maintain grid stability. Typically, the proposed method of managing variability of renewable resources is to add an energy storage component. However, there may be a lack of reliable, commercially proven, and cost effective storage unit compatible with a facility scale at the 100 s of kilowatts level or higher.


A cooling system for an electrical device includes a receptacle unit having a main opening with an inner chamber, a cooling unit operably associated with the electrical device arranged in the chamber of the receptacle unit, intake and exhaust openings arranged between the electronic device and the receptacle unit, an intake path extending from the intake opening to the cooling unit via the chamber of the receptacle unit and an exhaust path extending from the cooling unit to the exhaust opening via the inner space of the receptacle unit.

1. Field of the Invention
The invention is directed generally to cooling electronic devices and, more particularly, to an air-cooling system configuration for electronic devices arranged at places where sufficient cooling/exhaust air movement is not readily available, such as wall mounted touch screens or other electronic displays.
2. Related Art
It is widely known and recognized in the electronics industry that heat dissipation is a serious consideration in the design and operation of electronic devices. This is especially true for densely packaged electronic circuit components and in particular integrated circuit (IC) components together with printed circuit boards (PCB). It is known, for example, that to operate IC components at full power capability, there should be no or very little temperature difference between the IC components and ambient air. To achieve this, various techniques have been applied to cooling of the IC components, including blowing cooling air over the IC components. However, in many applications where forced air may be available, it may not be used because the amount of air is limited or insufficient, or enough space to implement an air-cooling system may not be available without elaborate structural reconfiguration.
Consumer electronic devices, for example, flat panel display devices such as a liquid crystal display (LCD), plasma monitors/television sets and the like, are typically stand alone type devices that are allowed to freely intake air from their surroundings to cool the internal IC components and PCBs, and hence are usually configured such that they do not have an internal cooling system. However, when these devices are situated where the amount of intake air is limited or insufficient and/or not enough space is readily available for implementing a proper cooling system, heat will build up and the device performance and life span often will be adversely affected.
In this same regard, it has become a trend for consumer electronic devices to become part of a building's structure including the mounting of televisions or other displays to a wall surface, and the like. Being in close association with the building structure creates additional disadvantages in the area of cooling the device. For example, when a flat panel display is mounted on or inserted in a compartment formed in a wall, the majority of its rear side where major ventilation and heat dissipation occur is blocked, thereby increasing the internal temperature.
With the advent of higher-end, faster operating, and more complex electronic devices, there is a need to cool these devices in a way that was not previously contemplated by either the stand alone devices or the other prior art approaches. Accordingly, there is a need for an efficient air-cooling system configuration for electronic devices used in situations where a sufficient amount of air is not readily available for heat dissipation, such as wall-mounted devices.

Air-cooling system configuration for touch screen