A method to manufacture a blowout preventer seal including disposing at least one insert and at least one elastomeric material in a mold, heating the mold to a cure temperature, curing the at least one elastomeric material, measuring a temperature of the at least one elastomeric material during the curing, adjusting a cure time and the cure temperature based on the measured temperature of the elastomeric material, and removing the cured blowout preventer seal from the mold.

1. Field of the Disclosure
Embodiments disclosed herein relate generally to blowout preventers used in the oil and gas industry. Specifically, embodiments relate to methods of curing and manufacturing seals for use in blowout preventers, in which the seals may include elastomeric and rigid materials.
2. Background Art
Well control is an important aspect of oil and gas exploration. When drilling a well, for example, safety devices must be put in place to prevent injury to personnel and damage to equipment resulting from unexpected events associated with the drilling activities.
Drilling wells involves penetrating a variety of subsurface geologic structures, or "layers." Occasionally, a wellbore will penetrate a layer having a formation pressure substantially higher than the pressure maintained in the wellbore. When this occurs, the well is said to have "taken a kick." The pressure increase associated with a kick is generally produced by an influx of formation fluids, which may be a liquid, a gas, or a combination thereof, into the wellbore. The pressure kick tends to propagate from a point of entry in the wellbore uphole (from a high-pressure region to a low-pressure region). If the kick is allowed to reach the surface, drilling fluid, well tools, and other drilling structures may be blown out of the wellbore. Such "blowouts" may result in catastrophic destruction of the drilling equipment (including, for example, the drilling rig) and substantial injury or death of rig personnel.
Because of the risk of blowouts, devices known as blowout preventers are installed above the wellhead at the surface or on the sea floor in deep water drilling arrangements to effectively seal a wellbore until active measures can be taken to control the kick. Blowout preventers may be activated so that kicks are adequately controlled and "circulated out" of the system. There are several types of blowout preventers, the most common of which are annular blowout preventers (including spherical blowout preventers) and ram blowout preventers. Each of these types of blowout preventers will be discussed in more detail.
Annular blowout preventers typically use large annular, rubber or elastomeric seals having metal inserts, which are referred to as "packing units." The packing units may be activated within a blowout preventer to encapsulate drillpipe and well tools to completely seal an "annulus" between the pipe or tool and a wellbore. In situations where no drillpipe or well tools are present within the bore of the packing unit, the packing unit may be compressed such that its bore is entirely closed. As such, a completely closed annular blowout preventer packing unit acts like a shutoff valve. Typically, the packing unit may be quickly compressed, either manually or by machine, to result in a seal thereabout and to prevent well pressure from causing a blowout.
An example of an annular blowout preventer having a packing unit is disclosed in U.S. Pat. No. 2,609,836, issued to Knox, assigned to the assignee of the present disclosure, and incorporated herein by reference in its entirety. The packing unit of Knox includes a plurality of metal inserts embedded in an elastomeric body, in which the metal inserts are completely bonded with the elastomeric body. The metal inserts are spaced apart in radial planes in a generally circular fashion extending from a central axis of the packing unit and the wellbore. The inserts provide structural support for the elastomeric body when the packing unit is radially compressed to seal against the well pressure. Upon compression of the packing unit about a drillpipe or upon itself, the elastomeric body is squeezed radially inward, causing the metal inserts to move radially inward as well.
Referring now to FIG. 1, an annular blowout preventer 101 including a housing 102 is shown. Annular blowout preventer 101 has a bore 120 extending therethrough corresponding with a wellbore 103. A packing unit 105 is then disposed within annular blowout preventer 101 about bore 120 and wellbore 103, Packing unit 105 includes an elastomeric annular body 107 and a plurality of metal inserts 109. Metal inserts 109 are disposed within elastomeric annular body 107 of packing unit 105, which are distributed in a generally circular fashion and spaced apart in radial planes extending from wellbore 103. Further, packing unit 105 includes a bore 111 concentric with bore 120 of blowout preventer 101.
Annular blowout preventer 101 is actuated by fluid pumped into opening 113 of a piston chamber 112. The fluid applies pressure to a piston 117, moving piston 117 upward and translating force to packing unit 105 through a wedge face 118. The force translated to packing unit 105 from wedge face 118 is directed upward toward a removable head 119 of annular blowout preventer 101, and inward toward a central axis of wellbore 103 of annular blowout preventer 101. Because packing unit 105 is retained against removable head 119 of annular blowout preventer 101, packing unit 105 does not displace upward from the force translated to packing unit 105 from piston 117. However, packing unit 105 does displace inward from the translated force, which compresses packing unit 105 toward central axis of wellbore 103 of the annular blowout preventer 101. In the event drillpipe is located within bore 120, with sufficient radial compression, packing unit 105 will seal about the drillpipe into a "closed position." The closed position is shown in FIG. 5. In the event a drillpipe is not present, packing unit 105, with sufficient radial compression, will completely seal bore 111.
Annular blowout preventer 101 goes through an analogous reverse movement when fluid is pumped into opening 115 of piston chamber 112. The fluid translates downward force to piston 117, such that wedge face 118 of piston 117 allows the packing unit 105 to radially expand to an "open position." The open position is shown in FIG. 4. Further, removable head 119 of annular blowout preventer 101 enables access to packing unit 105 such that packing unit 105 may be serviced or changed if necessary.
Referring now to FIGS. 2, 3A, and 3B together, packing unit 105 and metal inserts 109 used in annular blowout preventer 101 are shown in more detail. In FIG. 2, packing unit 105 includes an elastomeric annular body 107 and a plurality of metal inserts 109. Metal inserts 109 are distributed in a generally circular fashion and spaced apart in radial planes within elastomeric annular body 107. FIGS. 3A and 3B show examples of metal inserts 109 that may be disposed and embedded within elastomeric annular body 107. Typically, metal inserts 109 are embedded and completely bonded to elastomeric annular body 107 to provide a structural support for packing unit 105. The bond between annular body 107 and metal inserts 109 restrict relative movement elastomer within the elastomeric annular body 107. More discussion of the bonds between elastomeric bodies and metal inserts within a packing unit may be found in U.S. Pat. No. 5,851,013, issued to Simons, assigned to the assignee of the present disclosure, and incorporated herein by reference in its entirety.
Referring now to FIGS. 4 and 5, examples of packing unit 105 in the open position (FIG. 4) and closed position (FIG. 5) are shown. When in the open position, packing unit 105 is relaxed and not compressed to seal about drillpipe 151 such that a gap is formed therebetween, allowing fluids to pass through the annulus. As shown in FIG. 5, when in the closed position, packing unit 105 is compressed to seal about drillpipe 151, such that fluids are not allowed to pass through the annulus. In this manner, the blowout preventer may close the packing unit 105 to seal against wellbore pressure from the blowout originating below.
Similarly, spherical blowout preventers use large, semi-spherical, elastomeric seals having metal inserts as packing units. Referring to FIG. 6, an example of a spherical blowout preventer 301 disposed about a wellbore axis 103 is shown. FIG. 6 is taken from U.S. Pat. No. 3,667,721 (issued to Vujasinovic and incorporated by reference in its entirety). Spherical blowout preventer 301 includes a lower housing 303 and an upper housing 304 releasably fastened together with a plurality of bolts 311, wherein housing members 303, 304 may have a curved, semi-spherical inner surface. A packing unit 305 is disposed within spherical blowout preventer 301 and typically includes a curved, elastomeric annular body 307 and a plurality of curved metal inserts 309 corresponding to the curved, semi-spherical inner surface of housing members 303, 304. Metal inserts 309 are thus disposed within annular body 307 in a generally circular fashion and spaced apart in radial planes extending from a central axis of wellbore 103.
Additionally, ram blowout preventers may also include elastomeric seals having metal inserts. The large seals are typically disposed on top of ram blocks or on a leading edge of ram blocks to provide a seal therebetween. Referring now to FIG. 7, a ram blowout preventer 701 including a housing 703, a ram block 705, and a top seal 711 is shown. With respect to FIG. 7, only one ram block 705 is shown; typically, though, two corresponding ram blocks 705 are located on opposite sides of a wellbore 103 from each other (shown in FIG. 8). Ram blowout preventer 701 includes a bore 720 extending therethrough, bonnets 707 secured to housing 703 and piston actuated rods 709, and is disposed about central axis of a wellbore 103. Rods 709 are connected to ram blocks 705 and may be actuated to displace inwards towards wellbore 103. Rams blocks 705 may be pipe rams, variable bore rams, shear rams, or blind rams. Pipe and variable bore rams, when activated, move to engage and surround drillpipe and/or well tools to seal the wellbore. In contrast, shear rams engage and physically shear any wireline, drillpipe, and/or well tools in wellbore 103, whereas blind rams close wellbore 103 when no obstructions are present. More discussion of ram blowout preventers may be found in U.S. Pat. No. 6,554,247, issued to Berekenhoff, assigned to the assignee of the present disclosure, and incorporated herein by reference in its entirety.
Referring now to FIG. 8, ram blocks 705A, 705B and top seals 711A, 711B used in ram blowout preventer 701 are shown in more detail. As shown, top seals 711A, 711B are disposed within grooves 713 of ram blocks 705A, 705B, respectively, and seal between the top of ram blocks 705 and housing 703 (shown in FIG. 7). As depicted, ram block 705A is an upper shear ram block having top seal 705A, and ram block 705B is a lower shear ram block having top seal 705B. When activated, ram blocks 705A, 705B move to engage, in which shears 715A engage above shears 715B to physically shear drillpipe 151. As ram blocks 705A, 705B move, top seals 705A, 705B seal against housing 703 to prevent any pressure or flow leaking between housing 703 and ram blocks 705A, 705B.
Referring now to FIGS. 9A and 9B, top seals 711A, 711B are shown in more detail. As shown particularly in FIG. 9A, top seals 711A, 711B comprise an elastomeric band 751, elastomeric segments 753 attached at each end of elastomeric band 751, and a metal insert 755 disposed within each elastomeric segment 753. Top seal 705A for ram block 705A (i.e., the upper shear ram block) may also include a support structure 757 connected between elastomeric segments 753. As shown in a cross-sectional view in FIG. 9B, metal insert 755 disposed within elastomeric segment 753 has an H-shaped cross-section. The H-shaped cross-section of metal insert 755 should be understood that top seals 711A, 711B may be used with either pipe rams, blind rams, or shear rams (shown in FIG. 8).
Referring now to FIG. 10, a ram block 705A with a top seal and a ram packer 717A used in ram blowout preventer (e.g., 701 of FIG. 7) is shown. FIG. 10 is taken from U.S. Patent Application Publication No. 20040066003 (issued to Griffin et al. and incorporated herein by reference in its entirety). Instead of a shear rams (shown in FIGS. 7 and 8), FIG. 10 depicts a pipe ram assembly having a variable bore ram packer 717A comprised of elastomer and metal. As shown, variable bore ram packer 717A comprises an elastomeric body 761 of a semi-elliptical shape having metal packer inserts 763 molded in elastomeric body 761. Metal packer inserts 763 are arranged around a bore 765 of elastomeric body 761. As mentioned above with respect to pipe rams or variable bore rams, when activated, ram packer 717A (along with a corresponding ram packer oppositely located from ram packer 717A) moves to engage and surround drillpipe and/or well tools located in bore 765 to seal the wellbore.
For any seal mechanism comprising elastomers and metal in blowout preventers (e.g., packing units in the annular and spherical blowout preventers and top seals and ram packers in the ram blowout preventer), loads may be applied to contain pressures between various elements of the blowout preventers. For example, with respect to the annular blowout preventer shown in FIG. 1, as the fluid force is translated from piston 117 and wedge face 118 to packing unit 105 to close packing unit 105 towards central axis of wellbore 103, the fluid force generates stress and strain within packing unit 105 at areas and volumes thereof contacting sealing surfaces (e.g., wedge face 117 and drillpipe 151) to seal against wellbore pressure from below. The stress occurring in packing unit 105 is roughly proportional to the fluid force translated to packing unit 105.
As stress is incurred by blowout preventer seals, the material of the seals will strain to accommodate the stress and provide sealing engagement. The amount of strain occurring in the material of the seal is dependent on a modulus of elasticity of the material. The modulus of elasticity is a measure of the ratio between stress and strain and may be described as a material's tendency to deform when force or pressure is applied thereto. For example, a material with a high modulus of elasticity will undergo less strain than a material with a low modulus of elasticity for any given stress. Of the materials used in blowout preventer seals, the metal inserts have substantially larger moduli of elasticity than the elastomeric portions. For example, the modulus of elasticity for steel (typically about 30,000,000 psi; 200 GPa) is approximately 20,000-30,000 times larger than the moduli of elasticity for most elastomers (typically about 1,500 psi; 0.01 GPa).
Historically, when examining, designing, and manufacturing seals for blowout preventers, such as packing units for blowout preventers, the locations and amounts of stress and/or strain (i.e., stress concentrations, strain concentrations) occurring within the seal have been the largest concern and received the most attention and analysis. As the seal is subject to loads (e.g., repetitive and cyclic closures of a packing unit of an annular blowout preventer about a drillpipe or about itself), the magnitude and directions of the stresses and strains occurring across the seat are evaluated to determine the performance of the seal. A common technique used for this evaluation is finite element analysis ("FEA"). Specifically, FEA may be used to simulate and evaluate the stress and/or strain concentrations which occur across the seal under given displacement conditions.
When designing and manufacturing high strain elastomeric seals containing rigid inserts, there may be a significant discrepancy between the theoretical stress and strain predicted by FEA and actual stress and strain. Thus, current modeling and analysis techniques for blowout preventer seals may not provide adequate information to improve their design and manufacture.
Additionally, performance of a manufactured seal may also depend upon the properties of the elastomeric material used. Properties of the elastomeric material depend not only on the base material (elastomer) properties, but also on the degree of curing, or degree of crosslinking, of the elastomeric material obtained during seal manufacture. For example, excessively cured or crosslinked elastomeric material may be rigid and not function properly; i.e., curing may affect the modulus of elasticity of the elastomeric material. Under-cured elastomeric material may lack resiliency.
Accordingly, there exists a need for methods to improve the design, manufacture, and curing processes for blowout preventer seals.

Revised cure cycle for annular packing units


A new cultivar of Wisteria floribunda named ‘Ed's Blue Dragon’, characterized by its double pale blue and mauve flowers and its vigorous growth rate with ease of propagation.

The present invention relates to a new and distinct cultivar of Wisteria plant, botanically known as Wisteria floribunda 'Ed's Blue Dragon' and will be referred to hereafter by its cultivar name, 'Ed's Blue Dragon'. The new cultivar represents a new Japanese wisteria grown as a vine or shrub for landscape use.
'Ed's Blue Dragon' arose from a breeding project conducted by the Inventor in Los Gatos, Calif. Pollen from various unnamed plants in the Inventors breeding program was used to pollinate plants of 'Black Dragon' (not patented) and the resulting seeds pooled and sowed. The male parent is therefore unknown. 'Ed's Blue Dragon' was selected as a single unique plant in spring of 1996 from amongst the resulting seedlings.
Asexual reproduction of the new cultivar was first accomplished by grafting in Los Gatos, Calif. by the Inventor in 1997. Asexual reproduction by grafting and stem cuttings has determined that the characteristics of this cultivar to be stable and reproduced true to type in successive generations.


In a dual CDMA mode and FM mode receiver, a local oscillator selectively outputs a local oscillation signal for a CDMA mode or a local oscillation signal for an FM mode in response to a command. A mixer mixes the local oscillation signal with an intermediate frequency signal to produce a signal having a predetermined frequency. Filters assigned to a CDMA mode and an FM mode, respectively, each filters the output of the mixer. After an AGC amplifier has amplified the output of the filter, a digital signal processor demodulates the output of the amplifier. Switches are provided for selecting either a CDMA mode or an FM mode.

1. Field of the Invention
The present invention relates to a signal communication device and, more particularly, to a signal communication device operable both in a code division multiple access (CDMA) mode and in a frequency modulation (FM) mode.
2. Description of the Related Art
Typical of automobile and portable telephone systems are frequency division multiple access (FDMA) system and a code division multiple access (CDMA) system. The FDMA system assigns a single channel to a single frequency band width. For example, the American standard advanced mobile phone system (AMPS), which is implemented by the FDMA system, assigns a frequency band of 30 kHz to a single telephone channel.
A current trend in radio telecommunications is toward a digital cellular system, as distinguished from the conventional AMPS or similar analog cellular system. A digital cellular system is advantageous over the analog system in that it accommodates a greater number of subscribers, insures stable sound quality, has a secrecy function, and matches other digital services. Particularly, a CDMA system proposed by Qualcomm scatters 10 kHz coded voice data to a frequency band of 1.25 MHz and allows a plurality of conversation channels to share the same frequency band. This CDMA system is a promising system since it insures a frequency utilization efficiency ten times to twenty times that of the AMPS system.
Such a CDMA system is disclosed, for example, in a paper entitled "TIA/SIA INTERIM STANDARD" by TELECOMMUNICATIONS INDUSTRY ASSOCIATION, pages 6-1 to 7-42, and published in July 1993.
In North America, however, it is a prerequisite that a new digital system be introduced together with an apparatus also operable in the conventional AMPS system, so-called dual mode. Therefore, a receiver circuit built in a cellular telephone has to be adaptive to both of AMPS and CDMA.
To better understand the present invention, a brief reference will be made to a prior art receiver of the AMPS cellular terminal unit, shown in FIG. 1. The receiver is implemented as a double superheterodyne receiver.
The receiver includes an antenna 1, a band-pass filter 2 for filtering a high frequency signal coming in through the antenna 1, a high frequency amplifier 3, a first mixer 4 for combining the output of the amplifier 3 with a first local oscillation signal to produce a first intermediate frequency (IF) signal, a first IF filter 6 for filtering the first IF signal, a first IF amplifier 7 for amplifying the output of the IF filter 6, and a second mixer 8 for combining the output of the IF amplifier 7 with a second local oscillation signal to thereby output a second IF signal.
In operation, the antenna 1 receives a high frequency signal lying in the range of from 869.04 MHz to 893.97 MHz. The bandpass filter, or high frequency filter, 2 supplies a signal component lying in the above-mentioned range. The high frequency amplifier, or low noise amplifier (LNA), 3 amplifies the filtered signal component. The first mixer 4 mixes the output of the amplifier 3 with a first local oscillation signal, thereby producing a first IF signal. The first local oscillation signal is generated by a first local oscillator 5. Usually, the local oscillator 5 is implemented by a phase locked loop (PLL) synthesizer in order to change the frequency on a 30 kHz basis for channel selection. The first IF signal usually lies in a frequency band of 70 MHz or 90 MHz.
The first IF signal is further filtered by the first IF filter 6 so as to have spurious components thereof removed. The first IF amplifier 7 amplifies the filtered signal of the IF filter 6. The second mixer 8 mixes the amplified signal of the amplifier 7 with a second local oscillation signal to output a second IF signal whose frequency is usually about 450 kHz. The second local oscillation signal is generated by a second local oscillator 9. The second IF filter 10 filters the second IF signal for thereby removing spurious waves farther than the adjoining channels. A limiter amplifier 11 amplifies the output signal of the second IF filter 10 to saturation, thereby removing varying amplitude components. The output of the limiter amplifier 11 is applied to a frequency discriminator 12 with the result that voice, or FM signal, is reproduced. Although the limiter amplifier 11 removes amplitude components from the second IF signal, it outputs a voltage corresponding to a field strength, i.e., received signal strength indicator (RSSI). The receiver senses a received field strength by use of the RSSI signal. The second IF filter 10, limiter amplifier 11 and frequency discriminator 12, among others, are extensively used and available at extremely low cost.
Analog-to-digital converters (A/D) 13 and 14 convert the voice signal and RSSI signal to digital signals, respectively, and supply the digital signals to a digital signal processor (DSP) 15.
The circuitry shown in FIG. 1 cannot accommodate the CDMA system for the following reasons. As for the AMPS system, the band width per channel is less than 30 kHz and can be easily dealt with by the second IF filter whose frequency band is 450 kHz. However, when it comes to the CDMA system, the band width is as broad as about 1.2 MHz and cannot be handled by the second IF filter.
Furthermore, the AMPS system is an FM system and the received signal does not contain any amplitude information thereof. This allows an inexpensive limiter amplifier to be used. By contrast, the CDMA system is a four-phase phase shift keying (PSK) modulation system and the signal contains information even in amplitude modulation. Therefore, the inexpensive limiter amplifier cannot be used in the CDMA system. In addition, nonlinear processing is not available with the CDMA system since telephone signals of as many as about sixty subscribers exist together on a signal frequency channel.

Signal communication device operable in a CDMA mode and an FM mode


A technical device and an associated remote control is provided. The remote control includes a support and a contact. The technical device includes a support rail and a contact rail. The support, the contact, the support rail and the contact rail are adapted to one another and fashioned such that an optical and/or electrical effective connection is automatically produced between the contact and the contact rail via attachment of the remote control to the support rail.

1. Field of the Invention
The present invention concerns a technical device and an associated remote control that can be attached to the technical device.
2. Description of the Related Art
Operating controls for technical devices are increasingly realized as remote controls. In the one hand, this provides the advantage that the operating controls or elements are not only directly operable while on the device itself, while on the other hand cables for signal lines can be eliminated by a radio frequency or other wireless remote control. This advantage in particular has an effect in very complex technical devices that comprise a plurality of operating elements (such as, for example, display devices or controls) and must correspondingly be cabled in an elaborate and complex manner.
However, a problem of remote controls is that their energy supply cannot ensue over the same wireless connections as the signal transmission. The wireless transmission of energy cannot be used practically over comparably large distances. It is therefore typical to provide remote controls with batteries in order to have an independent voltage supply available. In view of the environmental impact and practical handling of one-time use batteries, rechargeable batteries are frequently used.
Rechargeable batteries wear out at points in time that are not precisely foreseeable, and must therefore be regularly charged. For this reason, a suitable electrical connection to a voltage supply must be provided, whereas the batteries can for the most part still be used in the remote control. For example, the remote control can therefore be plugged into a charging station.
The plug-in location at the charging station allows no flexibility with regard to the place at which the remote control must be located for charging. Moreover, the plug-in space is frequently positioned such that the remote control cannot be reached, or can only be reached in some of the possible use situations. In entertainment electronics, for example, such a plug-in space is frequently on the electronic device itself. In technical devices, the plug-in space can, for example, be located in the region of a control console, and cannot be reached at other workstations that can be spread around the technical device. The same is true for laboratory-technical and medical-technical devices.

Technical device and associated remote control


A method and circuitry for detecting when a PLL achieves phase and frequency-lock to a reference frequency with minimal hardware and power dissipation are disclosed. The invention takes advantage of existing blocks within a PLL to reduce the amount of circuitry required while at the same time reducing error due to mismatch. In one embodiment, the present invention combines a coarse lock-detect circuit with a fine lock-detect circuit to achieve fast response when the input reference is lost, while filtering occasional minor phase hits due to external or internal noise.

The present invention relates in general to integrated circuits, and in particular to a an improved lock-detect circuit for systems using phase-locked loops.
A phase-locked loop (PLL) is a circuit that operates to bring the phase of the output signal of a voltage-controlled oscillator (VCO) in alignment with that of a reference input signal. One common application for PLLs is in frequency synthesizers where a stable reference input clock is used to generate different frequencies. A conventional PLL includes a phase comparator that receives the reference input signal and the output of the VCO, and detects a phase difference therebetween. The error signal that represents the phase difference at the output of the phase comparator is then filtered and applied to the VCO to control its output frequency. By adjusting the phase of the VCO output signal in response to the magnitude of the phase error signal, this servo loop operates to minimize the error signal and to lock the phase of the reference signal with that of the input signal.
A PLL may fail to phase-lock and/or frequency-lock to the reference input frequency under several conditions. Some of these conditions are part of the normal operation and happen at expected times such as during the acquisition, or frequency transition modes. Other conditions are not part of the normal operation and are often unpredictable. These include loss of lock due to loss of input signal or significant degradation of the quality of the input signal (e.g., excessive jitter or modulation).
In many applications, it is crucial for the system to know at all times whether the system clock, which is usually generated by a PLL, is in lock condition in order to ensure data integrity. Hence, a lock-detect circuit becomes necessary.
Of the various lock-detect circuits that have been proposed, some require large frequency counters to monitor the frequency of the reference input signal and the signal at the output of the VCO divider. These schemes consume large area of silicon and power, and are only for frequency lock detection, not phase lock detection. Further, existing lock-detect circuits typically do not address the failure to lock situation when the reference frequency disappears or deviates significantly from the intended frequency.
There is therefore a need for an area and power efficient implementation of a lock-detect circuit that operates reliably under all conditions.


A filter assembly for removing particulate contaminants and chemical contaminants from an incoming dirty air stream for a fuel cell. The filter assembly also includes a noise suppression element that reduces sound waves or noise emanating from any equipment, such as a compressor. The filter assembly can include a particulate filter portion for removing physical or particulate contaminants, a chemical filter portion for removing chemical contaminants, or can have both portions.

Practical and efficient generation of electrical energy has been sought since the discovery of electricity. Hydroelectric, fossil fuel and nuclear generation plants and batteries have long been used to supply our electrical power needs. Power generation by use of fuel cells is a relatively recent development that is rapidly gaining acceptance for both commercial and residential applications. As compared with conventional fossil fuel burning powered sources, they are relatively clean and efficient. Fuel cells are electrochemical devices that efficiently convert a fuel's chemical energy directly to electrical energy. They chemically combine a fuel and oxidant without burning, thereby eliminating many inefficiencies and most pollution of traditional combustion power systems.
A fuel cell operates in principle much like a battery. However, unlike a battery, a fuel cell does not run down or require recharging. It will continue to produce energy in the form of electricity and heat as long as fuel is supplied to it. In general, a fuel cell consists of two electrodes (an anode and a cathode) sandwiched around an electrolyte. For example, for a PEM fuel cell, hydrogen and oxygen are passed over the anode and cathode electrodes respectively in a manner that generates a voltage between the electrodes, creating electricity and heat, and producing water as the primary byproduct. The hydrogen fuel is supplied to the anode of the fuel cell. Some consume hydrogen directly, while others use a fuel reformer to extract the hydrogen from, for example, a hydrocarbon fuel such as natural gas, methanol, ethanol, or gasoline. Oxygen enters the fuel cell at the cathode. The oxygen can be supplied in purified form or can come directly from atmospheric air.
The fuel cell uses a catalyst to cause the hydrogen atom to split into a proton and an electron, each of which takes a different path to the cathode. The protons pass through the electrolyte. The electrons create a useful electric current that can be used as an energy source, before returning to the anode where they are reunited with the hydrogen protons and the oxygen to form water.
Fuel cells are generally characterized by the electrolyte material which is sandwiched between the cathode and anode, and which serves as a bridge for ion exchange. There are five main known types of fuel cells. Alkaline fuel cells (AFCs) contain a liquid alkaline electrolyte and have been used primarily in space mission applications. Proton exchange membrane fuel cells (PEMFCs) contain a solid polymer electrolyte. Their low temperature operation, high power density with the ability to vary their output quickly to meet shifts in power demand make their use ideal for both mobile and stationary applications, such as powering vehicles or buildings. Phosphoric acid fuel cells (PAFCs) utilize a phosphoric acid electrolyte and are currently used for commercial power generation. Molten carbonate fuel cells (MCFCs) contain a carbonate salt electrolyte, which becomes molten at the operating temperature of about 650° C. Solid oxide fuel cells (SOFCs) use a ceramic electrolyte material and operate up to about 1000° C. Both the MCFCs and the SOFCs can use carbon monoxide as fuel.
Fuel cells have a vast range of potential applications. They can be used to produce electricity for homes, businesses and industries through stationary power plants. Fuel cells produce a direct current (dc) that must be inverted to alternating current for grid-connected applications or for use with most consumer products. However, future fuel cells could be operated in both grid-connected and non-grid-connected modes. For residential applications, smaller fuel cell power plants could be installed for the production of both heat and power. They could also be used to provide power to remote residential entities having no access to primary grid power, potentially eliminating the necessity of grid-connections.
In addition to the larger scale power production applications, fuel cells could replace batteries that power consumer electronic products such as laptop computers, cellular phones and the like and could even be micro-machined to provide power directly to computer chips. Another promising commercial application of fuel cells is their potential to replace the internal combustion engine in vehicle and transportation applications. The applications for fuel cells are virtually unlimited.
All of the known fuel cell configurations discussed above have a common need for oxygen as an integral ingredient for performing the cell's chemical process. Other power sources, such as internal combustion engines, including diesel engines, also have a need for oxygen. For most commercial applications it is desirable for such oxygen to be supplied directly from the atmospheric air. However, it is accepted that in today's world, all atmospheric air has some degree of contaminants present in it. Such contaminants can be relatively large such as loose debris, insects, tree blossoms or the like, or can be in the nature of small particulates suspended in the atmosphere such as dust, tree pollen, smog or smoke particulates. Chemical contaminants are also widely present in atmospheric air, whether as a result of man-made pollution or as those which naturally occur. Typical chemical contaminants might include volatile organic compounds such as aromatic hydrocarbons, methane, butane, propane and other hydrocarbons as well as ammonia, oxides of nitrogen, ozone, smog, oxides of sulfur, carbon monoxide, hydrogen sulfide, etc. Such contaminants may appear intentionally (such as in military environments or by terrorists) or unintentionally. Solution of the latter requirement becomes particularly acute when the fuel cell is used in a mobile application that subjects the fuel cell to many varied atmospheric conditions.
Since efficient fuel cell operation depends on a delicately balanced chemical reaction, contaminants in the air used by the cell can have a significant adverse effect on the cell's operation and, depending on their nature, can even cause the fuel cell to discontinue operation. It is important therefore, that the fuel cell system include a filtration system that is designed to eliminate harmful contaminants and one that enables the fuel cell to be used in a wide range of use environments. It is also important that other power generating equipment have a filtration system that is designed to eliminate harmful contaminants.
To obtain the amount of oxygen necessary for a fuel cell and other equipment to produce the desired energy output, it has been found desirable to pass the oxygen-bearing containing air through air movement equipment such as a compressor or fan located within the air flow stream supplied to the fuel cell or other equipment. Unfortunately, typical compressors produce significant undesirable and annoying noise levels. It is desirable, therefore, in a power generating system to reduce and to minimize the noise produced by and/or transmitted through the compressor and back into the environment. Since reduced system size is also typically desirable, it is preferable that the filtration and sound attenuation features of the system be physically reduced as small as possible and even preferably be combined within a single element or housing. The present invention addresses the above-identified needs and desires for an efficient and quiet system for use in a wide variety of applications, including fuel cell systems.
What is desired, therefore, is a power generator, such as a fuel cell, that functions within environments having a wide range of contaminants.

This patent is subject to a terminal disclaimer.

Filter assemblies and systems for intake air for fuel cells


A digital contents playback and a method for playing the same are provided. The digital contents playback comprises an arrangement unit for re-arranging digital contents stored in a recording medium by selecting a “breath first arrangement mode”, a “depth first arrangements mode” and a “disk all arrangement mode”. The “disk all arrangement mode” consists of a “filename first arrangement mode” and a “physical address first arrangement mode”. The “physical address first arrangement mode” arranges digital contents stored in the recording medium in physical address sequence. The arrangement unit arranges the digital contents to be suitable for a determined mode by user's selection, and the digital contents are played in the arranged sequence. When digital contents are arranged depending on the “physical address first arrangement mode” in a playback using a compact disk as a recording medium, driving distance of an optic pick-up module for playing digital contents on the compact disk is shortened, which results in reduction of power consumption and noise.

1. Field of the Invention
The present invention generally relates to a digital contents playback apparatus and a method for playing back the same, and more specifically, to an apparatus and method for digital contents playback wherein a user can select play sequence of digital contents such as a MP3 file stored in a readable/writeable medium and reduce noise and power consumption by selecting play sequence with reference to a physical address if necessary, and a method for replaying the same.
2. Description of the Related Art
Recently, digital contents have been produced and distributed as various types including audio, video or text, and various playback devices have been developed so that a user may enjoy the above digital contents off-line or on-line.
The digital contents can be freely read/written by a packet-writing method, and also deleted, moved and added on a recording medium. Furthermore, the digital contents can be classified and stored as hierarchical-structured files depending on selection of users.
As read/write compact disks become cheaper, portable digital contents (hereinafter, referred to as "file") playbacks with read/write compact disks have been widely used.
Files are recorded to tracks on a read/write compact disk, and sequentially recorded to an empty region located from the center of the disk to outside. If files are repeatedly deleted, moved and added, data corresponding to one file can be stored in various regions having different physical address. Although files are included in the same folder, the actual physical address of each file is remote from each other.
A digital contents playback with read/write compact disks arranges files in arrangement sequence of a "breadth first arrangement mode" or a "depth first arrangement mode", and play sequence depends on the arrangement sequence. As a result, the play sequence is fixed as one of the above-described modes.
The "breadth first arrangement mode" is to first arrange an upper layer folder, and the "depth first arrangement mode" is to first arrange the lowest layer folder and then sequentially arrange the upper layer folder.
For example, when folders A and B are included in the upper layer folders and folders C and D are included in the lower layer folder, the folders are arranged in A, B, C, D order according to the "breadth first arrangement mode" or in A, C, D, B order according to the "depth first arrangement mode". In both cases, the folders are arranged regardless of physical address of files included in the folders.
Therefore, when a music file with a MP3 format is stored in a read/write compact disk as digital contents and the digital contents are played in a digital contents playback, the digital contents playback frequently drives an optic pick-up module in a process for finding a physical address of a file corresponding to the next music. In the digital contents playback using the above-described compact disk, the optic pick-up module is driven by a DC motor to result in noise. Even when files are scattered physically, noise becomes more intense because the optic pick-up module is frequently driven.
Moreover, since play sequence has been determined depending on a mode regardless of physical address in a conventional digital contents playback using a compact disk, a path where an optic pick-up module moves becomes longer, which results in large power consumption.
Particularly, a portable digital contents playback is configured to use recording media such as a semiconductor memory (flash memory, etc.) or a hard disk as well as the above read/write compact disk in digital contents storage.
However, the conventional digital contents playback plays files, which are classified as a hierarchical structure and stored in a recording medium, in sequence depending on a previously fixed arrangement mode. As a result, the conventional digital contents playback does not cope with demand of users who wants to listen to contents files in various sequence.

Apparatus and method for digital contents playback


A method of communicating frames of management information includes loading a frame of management information from one of a plurality of stations into a respective one of a plurality of buffers. Whether the frame contains more than a predetermined number of bytes is determined. If an end of the frame is loaded into the respective one of the buffers, then a frame presence flag associated with said one of the plurality of stations is set. A request signal is transmitted to a station management module if the frame contains more than the predetermined number of bytes or if the buffer already contains management information associated with a previously loaded frame. The plurality of stations is polled to determine whether respective frame presence flags have been set. A buffer reading process is performed in a manner dependent upon whether the buffer reading process was triggered by one of the frame presence flags or by the request signal, to provide the station management module with the management information in the frame.

1. Technical Field
The present invention generally relates to the field of data communication networks. More particularly, the present invention relates to a novel system and method for communicating frames of management information in a multi-station network.
2. Discussion of Related Art
It is generally known that interfaces (e.g., switches, concentrators, and the like) may be used in a communication network, such as a local area network (LAN), a wide area network (WAN), or the like, to link client devices (e.g., desk-top computers) to one another and/or to a network server. Some of these interfaces also may be used to link client devices to other networks. The typical interface has multiple ports. Each port may be connected to a network interface card (NIC) of a respective client device. Inside the interface, each port typically has a respective interface module that controls the transmission of signals or information between a respective one of the client devices and other interface modules in the interface.
Such interface modules usually operate according to a well-know standard or protocol, an example of which is the fiber distributed data interface (FDDI) standard for token-ring communications. In the typical FDDI-based interface, each port is provided with a respective media access control (MAC) interface module. The functions carried out by the FDDI-based interface and its various MAC interface modules are typically managed pursuant to a well-known station management (SMT) protocol. As part of this SMT protocol, frames of management information are transmitted among an SMT module and the various interface modules.
Each MAC interface module typically is provided with its own processor and its own buffer. This arrangement, however, tends to be expensive. The cost of each processor may contribute significantly to the overall price of the interface. In addition, the size of the interface tends to increase with each additional processor. If the interface is provided in the form of one or more integrated circuit (IC) chips, the use of so many processors can make it difficult or impractical to provide the interface in a sufficiently compact chip or combination of chips.
While some interfaces have been developed so as to include a processor that is shared by multiple interface modules, the resulting interfaces typically include large buffers. This feature, in turn, makes the overall interface incompatible with, or otherwise impractical to implement using, some low-volume chip technologies.
While it has been known to provide 4 or 8 MAC interface modules on a single application specific integrated circuit (ASIC), the cost of the processors used by each such interface module typically makes the resulting interface too expensive. Other difficulties are presented by the size of each interface module's buffer.
There is consequently a need in the art for a more practical and economical method and system for communicating frames of management information. This need extends to a system and method that is compatible with ASIC chip technology.

Communication system and method for communicating frames of management information in a multi-station network


A spray dispenser. The spray dispenser has a spray mechanism and a bottle. The spray mechanism includes a sprayer and a siphon tube. The siphon tube defines a proximal end and a distal end. The proximal end of the siphon tube is in fluid communication with the sprayer. The bottle defines an inverted catchment therein adjacent a wall of the bottle. The siphon tube defines a generally U-shaped portion therein proximal to the distal end of the siphon tube. The distal end of the siphon tube is positioned within the inverted catchment. There is also a spray product and a method for spraying a liquid formulation onto a surface.

1. Field of the Disclosure
The disclosure relates to a spray dispenser. The disclosure further relates to a spray dispenser useful in spraying a liquid on a horizontal surface. The disclosure further relates to a method for spraying a liquid on a surface using the spray dispenser.
2. Description of the Related Art
Spray bottles are commonly used to spray liquid formulations onto surfaces for the purpose of cleaning, polishing, and the like. Spray bottles most commonly take the form of a trigger spray bottle employing a siphon tube to draw out and spray a liquid formulation. The siphon tube typically extends toward the bottom of the bottle.
A problem arises with trigger spray bottles when they are deployed horizontally to spray a liquid formulation on a horizontal surface, such as a floor, carpeting, kitchen counter, or table. In a conventional trigger spray bottle, the siphon tube is vertical. As the liquid formulation in the bottle diminishes in level with use, shifts of the formulation within the bottle may result in the siphon tube being exposed or unsubmerged, which would prevent the trigger sprayer bottle from functioning properly, i.e., from spraying the liquid formulation.
It would be desirable to have a spray dispenser that maintains spraying functionality when the dispenser is deployed horizontally and that would spray substantially all of the formulation from the bottle.


A packaged semiconductor device has a wiring substrate. A plurality of semiconductor device chips are connected to the wiring substrate by a use of bumps. A heat sink is bonded through a high heat conductive bonding layer to a surface of each of the semiconductor device chips. In addition, a package casing which accommodates the semiconductor device chips and the wiring substrate, has internal conductors which are positioned in the inside of the package casing. External connection pins extend outwardly from the package casing and are connected to corresponding internal conductors. The wiring substrate is connected to the internal conductors of the package casing via a flexible wiring circuit member. The flexibility of this wiring permits the thermal expansion and contraction to occur without breaking the connections to the bumps.

1. Field of the Invention
The present invention relates to a high density package structure for semiconductor devices, and more specifically to a high density, high heat dissipating, high reliable package structure for semiconductor devices.
2. Description of Related Art
Recently, semiconductor devices have a remarkable inclination of a large power consumption and a large chip size caused by increase of an integration density and speed-up of operation. In addition, for increased connection terminals, an increased package density and shortened delay times, consideration is now made on a flip-chip connection method which uses solder bumps of 100 .mu.m to 200 .mu.m in diameter. For example, semiconductor device chips are connected on a wiring substrate by use of for example bumps of Pb.sub.95 Sn.sub.5. The flip-chip connection using the bumps enables a high density package since a package area is substantially the same as that of the chip size, and also, a high speed signal propagation because of a shortened connection distance. Furthermore, since a whole surface of the chip is a connectable area, the number of external terminal pins can be increased.
However, a stress occurs due to difference in heat expansion between the wiring substrate and the semiconductor device chips in the flip-chip connection, and the stress will cause a thermal fatigue of the solder. As a result, heat cycle reliability is low.
Therefore, in order to obtain a connection reliability, it has been attempted to use mullite and aluminum nitride, which has a thermal expansion coefficient near to that of silicon, or silicon itself, as a substrate material.
At room temperature, most of heat generated from the semiconductor device chip is dissipated through a solid member in the inside of the package to atmosphere, by a thermal conduction. However, since the conventional package structure is such that the semiconductor device chips are connected to the wiring substrate by only the bumps having the diameter of 100 .mu.m to 200 .mu.m, the heat dissipation characteristics is not satisfactory. Therefore, it has been difficult to use the conventional package structure of the flip-chip type to a high power device.
In addition, in order to effectively dissipate a large amount of heat generated by semiconductor devices due to the increased integration density, Japanese Patent Application Laid-open No. 007456/1990 proposes a forced liquid cooling integrate circuit package, in which each of semiconductor device chips has its one principal surface connected to a wiring substrate by means of solder bumps, and its other principal surface connected to a flexible plate of a water jacket. In this structure, each semiconductor device chip is sandwiched and compressed between the wiring substrate and the flexible plate of a water jacket, so that the heat generated by each semiconductor device chip is dissipated from the one principal surface of the semiconductor device chip through the bumps and from the other principal surface of the semiconductor device chip to the flexible plate of a water jacket.
However, since a compressing stress acts on the bumps of 100 .mu.m to 200 .mu.m in diameter, fatigue is easy to occur in the solder bumps. In addition, it is difficult to work or process the semiconductor device chips, the solder bumps, a casing and the flexible plate of a water jacket, and they require an extremely high precision of size. Therefore, it is very expensive. Furthermore, since the cooling method is a forced cooling using a liquid, the package inevitably becomes a large size, and therefore, can be used in only a limited field of application.

Package structure for semiconductor device having a flexible wiring circuit member spaced from the package casing


Embodiments of the present disclosure relate to a solid-state supercapacitor. The solid-state supercapacitor includes a first electrode, a second electrode, and a solid-state ionogel structure between the first electrode and the second electrode. The solid-state ionogel structure prevents direct electrical contact between the first electrode and the second electrode. Further, the solid-state ionogel structure substantially fills voids inside the first electrode and the second electrode.

A traditional capacitor, such as an electrostatic capacitor, has a capacitance, which is based on an area of two electrostatic plates and a separating distance between the electrostatic plates. Such a capacitor has a dry separator between the plates. However, a supercapacitor is an electrochemical capacitor, which is an electrochemical energy storage device instead of an electrostatic energy storage device. In a typical supercapacitor, an electric charge is stored in an electrical double layer formed at an interface between an electrode and electrolyte solution, which is a liquid. A supercapacitor may include a pair of electrodes, which are separated by a porous separator. The electrodes and the porous separator are immersed in the electrolyte solution. The porous separator, filled with the electrolyte solution, is used to physically isolate the electrodes and prevent electrical shorting of the electrodes. The electrodes may include highly porous carbon particles, which may provide a very high surface area. As a result, a capacitance of a supercapacitor may be large compared to the capacitance of the traditional capacitor. Specific energy is defined as energy per unit mass. The energy stored in a capacitor is directly related to its capacitance and its voltage. Although a maximum operating voltage of a supercapacitor may be on the order of about one volt, the large capacitance may enable the supercapacitor to have a relatively high specific energy.
Response times of supercapacitors tend to be relatively slow. For example, response times may be on the order of hundreds of milliseconds to seconds. As such, supercapacitors may be used in applications that don't require fast response times. For example, such applications may use supercapacitors for energy storage. Integrated circuitry may include a supercapacitor to provide power for certain circuits, such as providing operational power or back-up power for memory circuits, computer circuits, digital circuits, analog circuits, the like, or any combination thereof. Such integrated circuitry may be used in portable equipment, which may need to be small, rugged, light weight, and function in harsh environmental conditions. Preventing leakage of the supercapacitor's liquid electrolyte solution in a portable device may be challenging. Also, exposure of the liquid electrolyte solution to moisture in air may damage the supercapacitor. Therefore, fabrication of the supercapacitor may have special manufacturing needs, thereby preventing integration of supercapacitors into standard manufacturing processes. Further, to keep the supercapacitor small and light weight, a high specific energy is needed. Thus, there is a need for a mechanically durable supercapacitor, which can be fabricated using standard manufacturing processes and has high specific energy.

The Regents of the University of California


A method of treating a shale-containing subterranean formation penetrated by a wellbore is accomplished by forming a carbon dioxide treatment fluid having a viscosity of less than about 10 mPa-s at a shear rate of about 100 s−1. The carbon dioxide treatment fluid is introduced into the formation through the wellbore at a pressure above the fracture pressure of the formation. In certain embodiments, the treatment fluid may be comprised of from about 90% to 100% by weight carbon dioxide and may contain a proppant. A method of treating hydrocarbon-bearing, shale-containing subterranean formation penetrated by a wellbore may also be carried out by forming a carbon dioxide treatment fluid and introducing the carbon dioxide treatment fluid into the formation through the wellbore at a pressure above the fracture pressure of the formation. The formation being treated may have a permeability of less than 1 mD.

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In the production of hydrocarbons from wells in subterranean formations, the formations are often stimulated to facilitate increased production of hydrocarbons. One method of stimulation is to hydraulically fracture the formation by introducing a fluid, known as a fracturing fluid or "frac fluid," into the formation through a wellbore and against the surface of the formation at a pressure sufficient to create a fracture or further open existing fractures in the formation. Usually a "pad fluid" is first injected to create the fracture and then a fracturing fluid, often bearing granular propping agents, is injected at a pressure and rate sufficient to extend the fracture from the wellbore deeper into the formation. If a proppant is employed, the goal is generally to create a proppant filled zone (aka, the proppant pack) from the tip of the fracture back to the wellbore. In any event, the hydraulically induced fracture is more permeable than the formation and it acts as a pathway or conduit for the hydrocarbon fluids in the formation to flow to the wellbore and then to the surface where they are collected. These methods of fracturing are well known and they may be varied to meet the user's needs, but most follow this general procedure.
The fluids used as fracturing fluids in such formations are typically fluids that have been "viscosified" or thickened, which facilitates fracturing and proppant transport. Viscosification of the fluid may be achieved through the addition of natural or synthetic polymers (cross-linked or uncross-linked). The carrier fluid is usually water or a brine that is viscosified with the viscosifying polymer, such as a solvatable (or hydratable) polysaccharide. The fluids used for hydraulic fracturing may also be viscosified or thickened with viscoelastic surfactants. These are non-polymer fluids that are typically formed from surfactants that are either cationic, anionic, zwitterionic, amphoteric or nonionic or employ a combination of such surfactants. In either case, such fracturing fluids are relatively costly due to the expense of the various components and additives used.
Additionally, while the use of such hydraulic fracturing fluids typically improves the overall permeability of the formation by establishing a high-permeability path between the newly-exposed formation and the wellbore, amounts of the viscosified fluids can leak off into the formation and may reduce the relative permeability in the invaded region after the treatment. In some cases, particularly near the fracture, the permeability to gas in some portions of the formation may be close to zero. Such low-permeability formations are commonly referred to as "tight". Clean up of these fluids is therefore an important consideration, which may add to the cost of treatment. And even with effective clean up, there is always the potential that some damage will remain.
The recovery of methane gas from tight subterranean formations has been a particular problem, especially in shales, such as Texas' Barnett Shale. In such formations, fracturing with conventional viscosified fracturing fluids may not be practical due to the expense and risk of damage to the already low permeability of the formation. One method of stimulating shale formations is through water or "slick-water" fracturing. In such fracturing operations, water, which may be combined with a friction reducing agent in the case of slick water, is introduced into the formation at a high rate to facilitate fracturing the formation. These fracturing fluids may produce longer although more narrow fractures and also use lighter weight and significantly lower amounts of proppant than conventional viscosified fracturing fluids. These water fracturing fluids are particularly useful in low-permeable, gas-bearing formations, such as tight-gas shale formations, where fracture width is of less concern. The water or slick-water fracturing fluids may be brine or fresh water, depending upon the properties formation being treated. The water fracturing fluids also require less cleanup than conventional viscosified fracturing fluids.
Water is in some ways a non-ideal liquid for shales because of the intrinsic water sensitivity of some shales and the behavior of trapped and/or adsorbed gases within the shales after the water-based treatment. The use of water fracturing may also be impractical in areas where water is scarce or in limited supply. Additionally, although water fracturing requires less cleanup than conventional viscosified fracturing fluids, residual water may remain in the formation after the fracturing operation. In certain instances, greater than 30% of the water used may remain in shale formations after the fracturing job. Additionally, other than facilitating the formation of fractures and channels in the formation, the water fracturing does nothing to facilitate further evolvement of methane or natural gas from the formation.
Accordingly, new and improved methods for stimulating production in hydrocarbon-bearing shale formations, particularly, methane or natural gas bearing formations, are needed.

Use of carbon-dioxide-based fracturing fluids


A binder for multiple sheets of paper employing a simple ratchet mechanism to secure the paper without the need for punching holes in the paper. The binding device includes a base member which is an elongated bar of L-shaped cross section with integral end plates. The binding device further includes a mating clamping member which is a slotted plate with an internally extending tongue. The back wall inside surface of the base member has a series of parallel, elongated saw-tooth ribs or grooves forming teeth with which the tongue engages in a ratchet-like manner. The teeth may be spaced in a staggered type arrangement to increase their effective number. Grooves forming teeth may also be placed on an outside surface of the base member back wall to increase the binding force. The end plates may be slotted to accept a finger adapted with notches on an underside to further ensure that the papers are securely bound.

1. Field of the Invention
This invention is directed generally toward an apparatus for binding multiple sheets of paper, and more particularly, to a ratchet mechanism to bind paper without punching holes in the paper.
2. Description of the Related Art
Considerable effort has been expended toward devices for quickly and easily binding together sheets of paper. Most of them do not focus on ways to improve the binding device so that less effort is required to bind the paper. Most of the prior art devices require that holes be punched in the paper, with the result that considerable time and effort must be used to modify the paper for binding. This requires that a device for punching the paper must be available and used before the paper can be bound.
U.S. Pat. No. 4,579,472 to Andrews discloses a modified two-hole clamping arrangement for holding sheets of paper. The folding arms are threaded through apertures in the main body of the binding device and then through holes in the paper. A top lid folds over and clamps the arms in place. The lid engages the main body by means of a snap action over a detent.
U.S. Pat. No. 4,529,226 to Weinman concerns a desk pad comprising a one-piece molded body portion for supporting a writing pad of paper. The Weinman apparatus requires fastening means such as screws or bolts which must pass through holes formed in the margin of the writing pad. The pad is perforated along the margin so that pre-cut portions of a sheet can be torn off as a note slip.
U.S. Pat. No. 3,612,709 to Miyamoto shows a loose-leaf binder clamping device having at least two posts which fit into opposing sockets. A plastic hinge joins the two main parts, where one part houses the pins and the other part houses the sockets. Again, the paper must be equipped with holes to receive the sockets.
Earlier advancements in the art also required that the paper to be bound be punched or in some way modified before being bound in a mechanism. Rice U.S. Pat. No. 885,648 discloses a binder having studs projecting upwardly through sheets to be bound and U.S. Pat. No. 795,611 to Hestmark discloses a bookbinder requiring notches be made in the sheets. Other examples of devices for quickly binding sheets of paper together are shown in Purcocks U.S. Pat. No. 4,453,850 and in Smith U.S. Pat. No. 3,507,601.
Although, binding devices which do not require hole punching are known in the art, there are disadvantages associated with them. Such binding systems can be found in a common office supply catalogue. For example the "GBC 1-Step Binding System" employs adhesives and the "Dennison 1st Impression Desktop Bindery" uses thermal technology to bind sheets of paper. These systems are intended to be permanent so it is not possible to remove the sheets without damaging them. A disadvantage of using adhesives is that all sheets must have their edges aligned together to contact an adhesive layer. This is extremely difficult to do without expensive aligning machinery. A disadvantage of either system is the requirement to use effectuating, enabling apparatus which takes up valuable space, needs a source of power, and is not readily portable, such as, in the user's briefcase.
Many so called "punchless" systems employ a spring tension clip similar to those employed on common clipboards. These systems are intended for temporary use and easily damage the paper by excessive spring forces applied over a very small area. Other so-called "punchless" binding systems are marketed as report covers. For example, the "Duraclip No-Punch Report Cover" is essentially bound by the force applied by a single sliding clip mechanism on the side of the binder. Such binding systems are limited to relatively small numbers of paper sheets (typically, about 50) and require a complete cover assembly which increases costs. Another example is represented by the "K&M Slide Lock" report covers which employ a plastic binding bar that slides over a report cover and papers to be bound.
Prior art mechanical binding devices generally have certain drawbacks. Either the paper must be punched or the mechanisms are relatively complex, or both. Some require the use of adhesives, heat or tape, among others. They may be relatively expensive to make or be made from expensive materials, such as metal.

Ratchet binding device for multiple sheets of paper


The present invention describes the process for the preparation of novel sesquiterpene oxide 3S,3aR,7aR,-6 isopropyl-1,1,3,3a-tetramethyl 1,3,3a,4,7,7a-hexahydro-isobenzofuran, of formula (I) by the reaction of elemol with per acid at a temperature range of 20 to 30° C. The invention also deals with the use of compound of formula (1) as a perfuming and flavoring agent

The compounds as defined in formula 1, have been detected, among other reaction products, during the course of studies on peracid dehydration of the sesquiterpene elemol.
A Japanese patent JP 54084551 by Nagakura et al, published on 5th Jul., 1979 describes the use in perfumery, for cosmetics and flavor for food, of substances, specifically of an oily and multi-component oxidation product obtained by treating a mixture, consisting of alpha elemene and delta elemene, resulting from heat dehydration of beta elemol or an alpha elemene mixture separated from the dehydration product, with a peracid.
It is important to point out that this document of prior art neither specifies structure nor stereochemistry of any component of the mixture except giving the infrared and NMR spectra of the mixture. Without doubt, on the basis of the experimental conditions described in the abstract of the document, for the preparation of mixtures of diastereomers of elemenes oxides derived each from alpha and delta elemenes one may, theoretically expect the sesquiterpene alcohols, 2 and 3 as shown in the scheme-I.
Compound of formula (1) is neither prepared synthetically nor isolated from a natural product and reported the prior art. Its use as a perfuming or flavoring ingredient is also not known in the prior art.
During the synthesis of a reference compound, dehydration of elemol was carried out. The pleasant smelling novel sesquiterpene oxides, compounds of the present invention, were obtained as side products during the reaction.

Sesquiterpene oxides as perfuming and flavoring agents

Council of Scientific and Industrial Research


A wide-coverage, high-capacity, switching network is modeled after a classical space-time-space switch. In the switching network, each of the space stages comprises geographically distributed optical space switches and the time stage comprises a plurality of geographically distributed high-capacity electronic switching nodes. User-access concentrators, each supporting numerous users, access the network through ports of the distributed optical space switches. A user-access concentrator is a simple device which need only have a single access channel to access the network, although two or more access channels may be used. Such a user-access concentrator can communicate with a large number of other user-access concentrators by time-multiplexing the access channel.

Network expansion is motivated by the prospects of new applications requiring a much higher capacity than that required by today's applications and is facilitated by the abundance of data transport capacity (often called bandwidth) of the optical telecommunication medium. The realizable capacity of a telecommunication network is virtually unlimited. A network structure that enables virtually unlimited expansion while providing a high service quality is desirable and its introduction is overdue.
Current communication networks, however, are complex. For example, the current Internet is complex and inefficient, with limited scalability and service capabilities: scalability relates to the ability of a network to grow to handle increasing traffic and accommodate a greater number of nodes; service capabilities relate to the ability of a network to provide flexible intelligent services and quality guarantees of various types of service. The current Internet lacks the versatility required in a growing global multi-service network, and its structure prohibits its growth without tremendous complexity and expense. This is further complicated by the unduly complex protocols that are an accumulation of patchwork performed since the Internet's inception.
Advances in optical and electronic technology have eliminated the need for complex structures and complex controls of telecommunication networks. A versatile inexpensive network scaling to a capacity that is orders of magnitude higher than the capacity of the current Internet is now realizable using simple network structures. The limitations that have led to the complexity and inefficiency of the current data networks have now been traversed. Adopting a simple network structure would enable the construction of an economical wide-coverage high-capacity high-performance network and the introduction of advanced communication services.
Applicant's U.S. patent application Ser. No. 09/286,431 filed on Apr. 6, 1999 and titled "Self-Configuring Distributed Switch ", discloses a wide-coverage network of a composite-star structure that greatly simplifies network routing and control while facilitating growth to very high capacities. The disclosed network is based on adaptive wavelength channel allocation in an optical-core comprising several core nodes. To simplify the control functions, the core nodes operate independently from each other. The network is fully meshed and the paths have adaptive capacities. A technique for overcoming optical-switching latency in such a composite-star structure is described in U.S. Pat. No. 6,486,983, titled "Agile Optical-Core Distributed Packet Switch", issued to Beshai et al. on Nov. 26, 2002.
It is well known that fine switching granularity can reduce the number of hops in a network and, hence, increase network efficiency. On the other hand, it is also recognized that some applications are better served through channel switching. Therefore, it may be beneficial to provide a network of mixed granularity. Applicant's U.S. patent application Ser. No. 09/671,140 filed on Sep. 28, 2000 and titled "Multi-grained Network" describes a network which includes edge nodes interconnected by core nodes having distinctly different granularities. The edge nodes switch multi-rate data traffic. The core may include core nodes that switch fixed-size data blocks, core nodes that switch channels or bands of channels, and core nodes that switch entire links. A core node that provides fine granularity by time sharing—for example, by switching data blocks occupying short time slots—must have a low switching latency in order to enable efficient time-sharing of wavelength channels.
The networks disclosed in the aforementioned patent applications require that each edge node have a sufficient capacity to enable direct linkage to the core nodes. Traffic sources may then access the edge nodes directly.
With the advent of fast optical switching devices, it may be desirable to relax the requirement that each edge node be of high capacity so that edge nodes of widely-varying sizes may be used while still maintaining the precious property of a small number of hops from any traffic source to any traffic sink. This would require exploring new network structures.


The present invention is a method and apparatus for generating a scaled correlation that is based on an estimate of the arrival time of a synchronization point in a received RF signal relative to a sampling clock, which is used to sample the received RF signal after down conversion. The scaled correlation may be used to validate the estimate of the arrival time of the synchronization point and, in certain embodiments of the present invention, may be used to update the estimate of the arrival times for subsequent synchronization points. Using the scaled correlation may provide arrival time estimates with a finer resolution and accuracy than the period of the sampling clock. Such arrival time estimates are important for timing-based applications, such as GPS receivers or navigation receivers.

RF receivers often use correlators to correlate a code in a received signal with a reference code. Once the received code is correlated with the reference code, other information in the received signal can be extracted. The other information may be used in applications associated with equipment containing the RF receiver. Certain applications rely on the arrival time of the received signal at the RF receiver. Such applications include a Global Positioning System (GPS) receiver, a navigation system receiver, or the like. Such systems determine distances to the RF receiver from a transmitter based on the precise arrival time of the received signal at the RF receiver. Specifically, during correlation, the arrival time of a synchronization point in the received signal is identified. The applications use the arrival time to determine distances and other arrival time dependent elements.
The accuracy of the identification of the arrival time of the synchronization point is based on the time precision of the correlation. Generally, a received signal is sampled using a sampling clock to create a sampled signal. The sampling rate is normally higher than the data bit rate in the sampled signal. The correlator works by comparing different groups of sampled bits with the reference code. The sampled signal is correlated when a group of sampled bits matches the reference code. Each group of sampled bits differs from the other groups by at least one sampled bit, therefore, the maximum time precision of the correlation is plus or minus one sample time. Typically, the sampling clock is asynchronous with the data bits in the received signal; therefore, the arrival time of the synchronization point as determined from the sampled signal may differ from the actual arrival time of the synchronization point in the received signal by plus or minus one sample time, which may result in an arrival time error. Applications requiring arrival time accuracy must tolerate an error of plus or minus one sample time. Increasing the sampling rate can reduce the arrival time error; however, an increased sampling rate may increase circuit complexity, cost, and power consumption. Additionally, some applications include RF signals having a plurality of synchronization points, and if transitions in the received signal are close to transitions of the sampling clock, then timing oscillations or discontinuities between samples associated with the synchronization points can occur. Such oscillations or discontinuities may be problematic for some applications. Some correlators address this problem by introducing a deliberate frequency offset between the sampling clock and the data rate of the received signal such that transitions in the received signal are always moving relative to transitions of the sampling clock. However, such correlators must correlate and extract data in the presence of the frequency offset, which may increase complexity, cost, and increase power consumption. Other correlators may correlate using two different reference code timings, which requires some knowledge of the timing of a synchronization point. The circuitry necessary to process all of the signals may increase complexity, power consumption, and reduce effective signal levels. Thus, there is a need for a correlation process that provides correlations having arrival time errors less than the sampling time; minimizes the effects of oscillations associated with sampling; is relatively simple and cost effective to implement; and is low powered.

Received signal correlation using a correlation scaling factor


The present invention relates to an adhesive composition for a wafer processing film, a wafer processing film, and a semiconductor wafer processing method. In the semiconductor wafer processing process such as a dicing process or a back grinding process, a delaminating force with respect to a wafer to be attached may be effectively reduced to improve process efficiency and prevent the wafer from being warped or cracked.

A wafer processing film is an adhesive film, which is used for securing a wafer in a wafer processing process such as dicing or back-grinding. Generally, such a wafer processing film temporarily secures the wafer in the wafer processing process and is removed from the wafer after the wafer processing process. With rapid progress in miniaturization and weight-reduction of electronic products or home appliances, large-diameter thin-film wafers included in a semiconductor package have been increasingly needed, and for this reason, physical properties of the wafer processing film are of utmost importance.

Adhesive composition for a wafer processing film


Described is a query optimizer comprising a query tuner that performs actual execution of query fragments to obtain actual results during compilation time, and uses those actual results to select a query plan. The actual results may be combined with estimates for fragments that were not executed. The tree may be traversed in a top-down traversal, processing every node. Alternatively, the tree may be traversed in a bottom-up traversal, re-deriving data for higher nodes as each lower level is completed. A limit, such as a time limit or level limit, may be used to control how much time is taken to determine the execution plan.

Given a database query of any complexity, there are typically many alternative ways to execute that query, each with (possibly widely) varying performance. To provide for efficient resource usage, and in particular fast query processing, when a query is submitted, a query optimizer is used to arrange that query into an execution plan. Standard query optimizers evaluate execution plans for queries by enumerating possible alternatives and estimating the time each of them will take to execute. Estimation in turn is done via statistics that reflect data distribution of the tables involved in the query.
However, the estimations are sometimes far off, especially for queries that have complex selection predicates and query constructs. In those cases, the query optimizer may choose a plan that is much slower than other alternatives.
The use of more sophisticated statistics, such as multi-dimensional histograms, has been proposed to improve the accuracy of estimation, and therefore improve the consistency and quality of chosen execution plans. However, these sophisticated statistics require complex code, and moreover, do not cover the full expressivity of typical query languages such as SQL.

Query execution plans by compilation-time execution


One embodiment of a semiconductor package described herein includes a substrate having a first through-hole extending therethrough; a conductive pattern overlying the substrate and extending over the first through-hole; a first semiconductor chip facing the conductive pattern such that at least a portion of the first semiconductor chip is disposed within the first through-hole; and a first external contact terminal within the first through-hole and electrically connecting the conductive pattern to the first semiconductor chip.

1. Field of Invention
Embodiments of the present invention generally relate to semiconductor packages, electronic system such as integrated circuit (IC) cards incorporating semiconductor packages, and methods of manufacturing the same. More particularly, embodiments of the present invention relate to semiconductor packages that increase contact area between a surface of the semiconductor package and an opposing surface of a card body and methods of manufacturing the same. Other embodiments of the present invention relate to semiconductor packages having reduced thicknesses and methods of manufacturing the same.
2. Description of the Related Art
A chip-on-board (COB) type semiconductor package is typically used to manufacture IC cards, e.g., smart cards. The IC cards are commonly used nowadays in various applications, replacing magnetic cards.
Referring to FIG. 1, the COB type semiconductor package includes a semiconductor chip 3 attached to a top surface of a semiconductor package substrate 4. An active surface 3a of the semiconductor chip 3 is electrically connected to a metal layer 5 disposed on another surface of the semiconductor package substrate 4 opposite the top surface, using bonding wires 6 that extend through wire holes 4a defined in the semiconductor package substrate 4. The bonding wires 6 are generally needed as the active surface 3a is disposed over the top surface of the semiconductor package substrate 4, opposite to the surface on which the metal layer 5 is disposed. The COB type semiconductor package is coupled to a card body 2 using an adhesive (not shown) between a surface 1a of the COB type semiconductor package and an opposing surface of the card body 2. In particular, the COB type semiconductor package is disposed within a cavity 2a defined in the card body 2.
The bonding wires 6 inevitably protrude from the active surface 3a of the semiconductor chip 3 to a certain height, thereby forming a loop where the wires 6 extend away from the active surface 3a and then bend toward the metal layer 5. An encapsulant 9 is also provided so as to encapsulate the wires 6. A sufficient amount of encapsulant 9 must be, therefore, provided to protect the wires 6 from the external environment. Accordingly, the encapsulant 9 creates a relatively large molding region "B", leaving a relatively small bonding region "A" where the surface 1a of the semiconductor package and an opposing surface of the card body 2 can be bonded to each other. Furthermore, because the bonding wires 6 need to be formed on both sides of the semiconductor chip 3, the length of the molding region "B" is additionally increased and the length of the bonding region A is further reduced while the total length of the available package system is limited.
It has been also discovered that edges of the substrate 4 tend to deform during manufacturing of the COB type semiconductor package. Thus, because the bonding region "A" is relatively small with the conventional system, the substrate 4 tends to separate from the card body 2 and the resulting IC card can be easily damaged or broken.
These problems can become more severe as the size of the semiconductor chip 3 increases and the package system or the IC card is subject to a harsher environment.
FIG. 2 is a cross-sectional view of another conventional package system to solve the above discussed problems.
Referring to FIG. 2, a conventional package system can be provided as a flip-chip-type COB package system. As shown in FIG. 2, an IC card includes a card body 12 having a cavity 12a defined therein. A semiconductor chip 13 attached to a semiconductor package substrate 14 to form a flip-chip-type COB semiconductor package. In the flip-chip-type COB semiconductor package, the active surface 13a of the semiconductor chip 13 is electrically connected to a metal layer 15, using conductive bumps 18 which are coupled to intermediate metal layers 17. In turn, the intermediate metal layers 17 are electrically connected to metal layers 15 by conductive vias 16 that extend through the package substrate 14. The semiconductor package is bonded to the card body 2 using an adhesive (not shown) between a surface 11a of the flip-chip-type COB semiconductor package and an opposing surface of the card body 2.
The conductive bumps 18 protrude from the surface of the semiconductor chip 13 away from a bottom surface of the cavity 12a and an encapsulant 19 is provided so as to encapsulate the conductive bumps 18. However, a sufficient amount of the encapsulant 19 must also be provided to adequately fix the semiconductor chip 13 to the intermediate metal layers 17 and the substrate 14.
Accordingly, the encapsulant 19 maintains a relatively large molding region "B", leaving a relatively small bonding region "A" where an adhesive can be applied between the surface 11a of the semiconductor package and an opposing surface of the card body 12. The substrate 14 or the semiconductor package also tends to separate from the card body 12 as in the IC card discussed in FIG. 1. Moreover, the presence of the intermediate metal layers 17 tends to increase the overall thickness "T" of the flip chip type COB semiconductor package system and increase the cost and complexity of manufacturing the flip-chip-type COB package system. Thus, even with the package system discussed with respect to FIG. 2, the above discussed problems are not sufficiently solved.
The present invention addresses these and other disadvantages of the conventional art.

Semiconductor package, integrated circuit cards incorporating the semiconductor package, and method of manufacturing the same

Maetan-dong, Yeongtong-gu, Suwon-si, Gyeonggi-do


The magnetic control device (1) for a timepiece comprises a sealed tube (3) which comprises a blind end inserted into an opening of the timepiece, whereas the other end of the tube opens towards the outside. A control stem (12) is provided in order to slide inside the tube (3). It carries a magnet (21) which is displaced integrally with the stem inside the tube. By manipulating the end of the stem which emerges from the tube (3), the wearer of the watch can make the magnet selectively occupy three positions. A first and a second magnetic sensor (22, 23) with two states are disposed inside the timepiece along the sealed tube so that three different combinations of a state of the first sensor (22) with a state of the second sensor (23) are respectively associated with three predefined positions of the first magnet (21).

Such magnetic control devices are already known to the person skilled in the art. The patent document U.S. Pat. No. 4,038,814 describes in particular several embodiments of such a device. In particular, the embodiment described with reference to FIGS. 6 and 7 relates to a wristwatch of a generally rectangular exterior form, and one of the sides of which carries a guide rail. A plastic cursor containing a magnet is provided in order to slide along this rail. A non-specified number of reed contacts are disposed inside the watch facing the guide rail. By making the magnet slide, the wearer of the watch can selectively close one or other of the reed contacts and thus can control the watch. This control device functions therefore without mechanical or electrical connection between the outside and the inside of the watch.
This device of prior art has certain defects. First of all it is not unobtrusive since the guide rail extends practically over the entire length of one of the sides of the watch. Furthermore it does not appear that it is possible to reduce greatly the size of this prior art device. In fact the described configuration makes it necessary to dispose all the reed contacts side by side in one line. However, the width of the smallest reed contacts known approaches a millimeter. Furthermore, the magnetic field must be intense enough to act through the thickness of the middle part of the watch. In these conditions it is necessary to space the contacts sufficiently apart in order that two contacts are not closed at the same time.
One object of the present invention is therefore to provide a control device which functions without a mechanical or electrical connection between the outside and the inside of the timepiece and which is more compact than those of prior art.
Another object of the present invention is to provide a control device within which the amplitude of the translational movement which the control member must perform is greatly reduced.
Another object is to provide a magnetic control device which can have the exterior appearance of a traditional mechanical control device.
Yet another object of the present invention is to provide a magnetic control device, the control member of which can be adapted easily in order to be actuated equally in rotation, in the manner of a traditional control stem.

The Swatch Group Research and Development Ltd


A device for holding a stick or rod of spreadable material includes a sleeve or container open on one side, an element co-acting with the stick, and a hand-operated means for varying the distance between the edge of the open side of the sleeve and the stick element. The stick or rod of spreadable material can be an adhesive stick or a wax stick. The stick of spreadable material is packaged separately from the device in an envelope of thin material, and the container includes means for securely holding an envelope of thin material suitable for packaging the stick.

1. Field of the Invention
The invention relates generally to a device for holding a stick or rod of spreadable material such as an adhesive stick, wax stick and the like, whereby a manually actuated mechanism of the device permits a user to extend a portion of the stick from an associated container for application of a spreadable material to a surface.
2. Discussion of Related Art
Known devices for holding a stick of spreadable material may include a sleeve not only as container but also as packaging for the spreadable material. Once the material is used up the whole container is discarded, causing an environmental impact.

Holder for a stick of a spreadable substance

Henkel Kommanditgellschaft Auf Aktien (KGaA)


A method (300, 400) of and server (200) for providing assistance with control of a subscriber device is described. The method comprises receiving an instruction message (303) via a network that corresponds to spoken instructions from the subscriber device; converting the spoken instructions to control commands (309); providing a control message corresponding to the control commands (313); and sending the control message to the subscriber device (315), thereby assisting with the control of the subscriber device.

Electronic devices such as communications units or subscriber devices providing data and voice services for user operating in corresponding systems are known. Operating these devices or units by interacting with a keypad or keyboard and display can be challenging when the user is otherwise preoccupied. It is known to include voice recognition systems to assist with controlling these devices for some purposes, however voice recognition systems are often marginal, suffer in high ambient noise environments, and can be a burden if the recognition system needs to be trained.
Controlling electronic devices or communications units from applications, for example, has been contemplated but such control has been limited to APIs (application program interfaces) where the interface details are defined according to the API. It is known to download software including applications to communication units as well as to configure the units. With these approaches there is a security risk and thus only highly trusted sources can have access to the unit. Clearly a need exists for methods and apparatus for providing assistance to a communications unit and preferably this assistance would be widely available over for example a network.

Providing assistance to a subscriber device over a network


A method for determining a time frame for when a freezer having a compressor should be defrosted include the steps of measuring compressor cycling over time, determining a change in compressor cycling over time, and determining from the change in in compressor cycling over time determined a time frame for when the freezer should be defrosted.

Freezers are used in home settings to keep food items frozen and in laboratory/manufacturing settings to keep samples, specimens, materials, ingredients, reactants etc. frozen. Freezers for home use usually operate at temperatures from −18 C to −35 C. Laboratory/manufacturing freezers operate in similar ranges but can also operate at significantly lower temperatures such as in the −20 C to −150 C range (e.g. −80 C). Cryogenics principles take over at temperatures below −150 C.
Over time, these freezers can acquire ice build up on interior surfaces. Ice also builds up along the door edge and can break the door seal thereby causing the freezer to have an air gap, which can result in more ice build up due to humid air entering the interior of the freezer. As ice builds up on interior surface and/or causes air gap failures, freezer performance can degrade which results in reduction in the efficiency of the freezer and an increase in compressor stress. Furthermore, as ice builds up in freezer can lead to eventual failure of the freezer's ability to maintain its operating temperature and ability to keep contents at desired temperatures.
Currently freezer defrosts are performed when visual inspection of the freezer reveals a need for defrost or in compliance with preset freezer defrost schedules (e.g. e.g. at every week, every month, every six months, every year, etc.). During each defrost event, the contents of the freezer are transferred to a different freezer OR the contents are discarded while the freezer is shut down, warmed up, and defrosted. Freezer defrosts are time, labor, resource and even a material intensive events which is why they are often delayed as long as possible (even if scheduled) and oftentimes delayed until freezer failure.
Improvements in determining when a freezer needs to be defrosted are strongly desired.

Method and apparatus for determining freezer status