An asynchronous data transmitting apparatus includes data signal transmission lines; two control transmission lines having a minimum delay and maximum delay respectively; a transmitter; and a receiver. The transmitter includes a data transmitting unit that transmits a data signal through the data signal transmission lines, depending on a transmit clock; and control transmitting units that transmit control signals through the control transmission lines, depending on the transmit clock. The receiver includes a receive clock generator that generates a read clock from the control signals; and a data receiving unit that receives the data signal through the data signal transmission line, depending on the read clock.

1) Field of the Invention
The present invention relates to an asynchronous data transmitting apparatus.
2) Description of the Related Art
Asynchronous data transmitting apparatuses includes a transmitter and a receiver that are connected via parallel transmission lines. The transmitter transmits data signals to the receiver by a transmit clock and a receive clock and the receiver receives the data signals by a receive clock. In other words, the transmitter and receiver operate asynchronously from each other.
FIG. 16 is a block diagram of a conventional asynchronous data transmitting apparatus. FIG. 17 is a timing chart to explain the data receiving when a skew occurs in the data of the asynchronous data transmitting apparatus shown in FIG. 16. A transmitter 100 and a receiver 200 are connected, for instance, via three signal transmission lines 301, 302, and 303 that are parallel transmission lines. A transmit clock CLOCK_A of the transmitter 100 and a receive clock CLOCK_C of the receiver 200 are generated independent of each other with no fixed phase relation between the CLOCK_A and the CLOCK_C.
In the transmitter 100, three flip-flops 111, 112, and 113 form a synchronous circuit and read three bits of transmitted data of DATA_0, DATA_1, and DATA_2, in synchronization with the CLOCK_A. Moreover, the flip-flops 111, 112, and 113 deliver the transmission data to signal transmission lines 301, 302, and 303, as data of DATA_0A, DATA_1A, and DATA_2A, respectively.
In the receiver 200, three flip-flops 211, 212, and 213 form a synchronous circuit and read transmission data of DATA_0B, DATA_1B, and DATA_2B from the three signal transmission lines 301, 302, and 303, in synchronization with the CLOCK_C. Moreover, the flip-flops 211, 212, and 213 deliver the data read to a processing system, as data of DATA13 0C, DATA_1C, and DATA_2C.
In such an asynchronous data transmitting apparatus, the transmitter and receiver communicate control signals in order to acquire an appropriate timing for the transmitting or the receiving. Therefore, since the receiver allows the receiving of the data signal at the time when receiving the control signals from the transmitter, there is no problem with a data delay time on the signal transmission lines.
However, in the asynchronous data transmitting apparatus, the timing when the transmission data changes and the timing when the data is read by the receive clock are completely asynchronous. Hence, at times, a reading edge of the receive clock comes in a period when the transmission data changes. As a result, following two problems arise.
The first problem is as follows. When the data to be read in the flip-flops completely overlaps with the timing of data reading, the data reading remains incomplete. As a result, a metastable state occurs in which the output of the flip-flops ends up with an intermediate potential, and the changed signals are reconverted to the original state.
The second problem, even though it may not cause metastability, is as follows. If in the parallel transmission lines, which transmit the plural bit data in parallel, the delay amount differs in each of the transmission lines, then at times the timing of data reading between the parallel databits may precede or follow the timing when the data changes. Thus, as shown in FIG. 17, a combination of such databits is received which do not exist at the transmitting end. The difference in the data delay amount is called a skew. A detailed explanation of the reception operation when a skew occurs in the data of the asynchronous data transmitting apparatus is given next with reference to FIG. 17.
The transmitter 100 sends, as the transmission data DATA_2A, DATA_1A, and DATA_0A, databits "100", "011", and "100" in the same sequence, in synchronization with the transmit clock CLOCK_A. The three signal transmission lines have different delay amounts. The delay amount in the signal transmission lines goes on increasing in the sequence of the signal transmission line 303 that carries the transmission data DATA_0A, the signal transmission line 302 that carries the transmission data DATA_1A, and the signal transmission line 301 that carries the transmission data DATA_2A.
As a result, the time at which the change of databit occurs is different in the transmission data DATA_2B, DATA_1B, and DATA_0B reaching the receiver 200. That is, the change takes place earliest in the transmission data DATA_0B, then in the transmission data DATA_1B, and last in the transmission data DATA_2B. The receiver 200 reads the transmission data in the sequence DATA_2B, DATA_1B, and DATA_0B at a data reading timing 401 that is in synchronization with the leading edge of the receive clock CLOCK_C.
At this time, in the first transmission data DATA_2B, DATA_1B, and DATA_0B, the data reading timing 401 falls after the change in the databits. Consequently, the databit of the reception data DATA_2C, DATA_1C, and DATA_0C will be the same as the databit of the transmission data, namely "100".
However, in the second transmission data DATA_2B, DATA_1B, DATA_0B, the data reading timing 402 precedes the transition point in the transmission data DATA_2B whereas it falls after the transition point in the transmission data DATA_1B and DATA_0B. Consequently, the databits of the reception data DATA_2C, DATA_1C, and DATA_0C become "111", as compared to the databit "011" of the transmitting end. As a result, the receiver receives an incorrect data and consequently performs an incorrect operation.
A number of ideas as well as preventive measures have been proposed for circumventing the first problem, that is, the metastable state. However, regarding the second problem, that is, a skew between the data, it is practically not possible to eliminate the problem completely as the timing of the receive clock cannot be predicted. An incorrect data is read in the asynchronous data transmission when there is a skew between the data and when the reading of data and the change in data coincidentally occur at the same time. Thus, the probability that an incorrect data is read is very low.
Consequently, the conventional technologies, as disclosed in Japanese Patent Application Laid-Open No. 6-54016 (hereinafter, "first conventional art") and Japanese Patent Application Laid-Open No. 4-178047 (hereinafter, "second conventional art"), focus on reducing the skew between the data as much as possible and thereby reducing the probability of reading an incorrect combination of data at the receiving end.
In the first conventional art, a skew correction circuit is disclosed, which includes a detecting unit that detects, from edges that must have the same timing, the edge of one transmission signal from among plural transmission signals transmitted by parallel transmission lines, a correction signal generating unit that generates correction signals according to the edge cycle of the edge detected by the detecting unit, and a correction unit that synchronizes the edges of the plural transmission signals with the correction signals generated by the correction signal generating unit and then outputs in synchronization all those edges.
In the second conventional art, a skew correction system for obtaining a skew-corrected data is disclosed, which includes a skew measurement signal pattern detecting circuit-cum-skew value detecting circuit that detects, after receiving from the receiving end the predetermined data set beforehand, the delay amount of the data with maximum phase advancement, a control circuit that outputs a control signal to correct the delay amount, based on each delay amount detected by the skew measurement signal pattern detecting circuit-cum-skew value detecting circuit, and a skew correction circuit that selects and outputs, from among the parallel outputs, the data on which skew correction is carried out by the control signal.
As the asynchronous data transmission is employed in a semiconductor integrated circuit, care is always taken when designing the transmission line. However, it is still practically not possible to reduce the skew between the data occurring in the parallel transmission lines to zero. As a large number of asynchronous data transmissions are employed in the recent large-scale semiconductor integrated circuits, it is not possible to ignore the problem of a skew between the data and incorrect operations may frequently occur as a result inside the apparatus itself. However, especially in case of the large-scale semiconductor integrated circuits, provisions made to eliminate incorrect data reading due to a skew between the data are insufficient. Thus, active measures to find a fundamental solution are expected in order to avoid incorrect data reading.


The invention discloses silaanalogs of oxazolidinone compounds, to pharmaceutical compositions and to the synthesis of the oxazolidinone derivatives of formula I. The invention further relates to methods of treating a subject suffering with gram positive pathogens including those resistant to methicillin and vancomycin using the compound(s) or modulation of coagulation properties of blood-clotting cascade or compositions of the oxazolidinone derivatives of the invention.

Increased resistance of gram positive pathogens such as Staphylococcus aureus and Enterococcus faecium to conventional antibiotics led to the introduction new class of compounds with good activity. The oxazolidinone have a unique mechanism of action that is different from other antibiotics. The exact mechanism of antibacterial activity of oxazolidinone has not been established, but they appear to exert their inhibitory activity by interfering with an early step in protein synthesis in a generally bacteriostatic manner. Linezolid is the first antibiotic belonging to the new class of oxazolidinone compounds, developed in 1990s and first approved for use in 2000, it is the first commercially available 1,3-oxazolidinone antibiotic possessing excellent antibacterial activity against a wide variety of gram-positive pathogens including those resistant to methicillin and vancomycin. Linezolid is a synthetic oxazolidinone antimicrobial agent chemically designated as (S)—N-({3-[3-fluoro-4-(morpholin-4-yl)phenyl]-2-oxo-1,3-oxazolidin-5-yl}methyl)acetamide. Linezolid has demonstrated high in vitro antibacterial activity against Mycobacterium tuberculosis and has been used to treat complicated cases of resistant TB in several programmes. While the recommended use of linezolid is restricted to 28 days, with dosage at 600 mg twice daily, drug-resistant TB requires a much longer treatment duration (˜2 years), and therefore, carries an increased risk of adverse effects. This drug suffers from poor pharmacokinetics which led to high dose, i.e., twice daily. Also there are several cases of developing linezolid resistance. By this silicon-switch approach, one can expect to improve pharmacokinetic properties which in turn may reduce the dose of the drug. More importantly, the problem of resistance development can be addressed as there is a structural difference in new sila analogs.
As of 2009, linezolid is the only marketed oxazolidinone, although others are in the process of development. As a protein synthesis inhibitor, it stops the growth of bacteria by disrupting their production of proteins. Linezolid targets ribosomes, inhibits the initiation step of protein synthesis by preventing the formation of functional 70S initiation complex, which is essential to the bacterial translation process and kills bacteria. Linezolid is used for the treatment of vancomycin-resistant Enterococcus faecium, including cases with concurrent bacteremia, treatment of nosocomial pneumonia, complicated and uncomplicated skin and skin structure infections (including diabetic foot infections without concomitant osteomyelitis) and community-acquired pneumonia caused by susceptible strains of specific organisms. Although bacterial resistance to linezolid has remained very low since it was first detected in 1999, however, the world wide reports on development of resistance to linezolid are constantly increasing.
Structurally related PNU-100480 is currently being developed for the treatment of both drug resistant and sensitive tuberculosis (TB).
Another related compound rivaroxaban (BAY 59-7939) is an oxazolidinone derivative optimized for inhibiting both free Factor Xa and Factor Xa bound in the prothrombinase complex. It is a highly selective direct Factor Xa inhibitor with oral bioavailability and rapid onset of action Inhibition of Factor Xa interrupts the intrinsic and extrinsic pathway of the blood coagulation cascade, inhibiting both thrombin formation and development of thrombi. Rivaroxaban has predictable pharmacokinetics across a wide spectrum of patients.
Therefore, it is necessary to develop an effective alternative belonging to the oxazolidinone group of compounds having activity against a wide variety of gram-positive pathogens including those resistant to methicillin and vancomycin as the oxazolidinones are proved to be effective in inhibiting bacterial translation process than the existing ones. The compounds of the present invention are useful antimicrobial agents, effective against a number of human and veterinary pathogens, including gram-positive aerobic bacteria such as Staphylococci, Streptococci and Enterococci as well as anaerobic organisms such as Bacteroides spp. and Clostridia spp. and acid-fast organisms such as Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium spp. The compounds of the present invention are also useful in modulation of coagulation properties of blood-clotting cascade.

Sila analogs of oxazolidinone derivatives and synthesis thereof

Council of Scientific & Industrial Research


A semiconductor slider including an integral spin valve transistor (SVT) having a read width of 250 nm or less disposed on a monolithic semiconductor. substrate, useful in magnetic data storage applications. The monolithic slider may also include other magnetic and semiconductor transistor structures and is fabricated in a single process using standard thin-film processing steps. The SVT includes a sensor stack having a top surface and including a first ferromagnetic (FM) layer in contact with and forming a Schottky barrier at the monolithic semiconductor substrate, a FM shield layer disposed over the sensor stack and in electrical contact with the top surface thereof, a SVT emitter terminal coupled to the FM shield, a SVT collector terminal coupled to the substrate and a SVT base terminal coupled to the first FM layer. The sensor stack may include a spin valve (SV) stack or a tunnel valve (TV) stack, for example.

1. Field of the Invention
This invention relates generally to spin valve transistor structures for magnetic read heads and more particularly to an integral spin valve transistor (SVT) structure formed in a semiconductor slider without the usual SVT wafer bonding step.
2. Description of the Related Art
Magneto-electronic devices with improved magnetic sensitivity are vital to increasing magnetic data storage densities. Giant magnetoresistance (GMR) sensors using only two layers of ferromagnetic (FM) material, the free (sensing) layer and the pinned (reference) layer, separated by a layer of non-magnetic conductive material (e.g., copper) are generally referred to as spin valve (SV) sensors and represent a major improvement that relies on the spin-dependent scattering effect. In SV sensors, the resistance of a spin valve (SV) to a sense current varies as a function of the spin-dependent transmission of the conduction electrons between two magnetic layers separated by a nonmagnetic spacer layer and the accompanying spin-dependent scattering that occurs at the interface of the magnetic and non-magnetic layers and within the magnetic layers. The SV stack may operate with sense current-in-the-plane (CIP) of the layers or with sense current-perpendicular-to-plane (CPP) of the layers.
Later, a new class of MR sensors, herein denominated tunnel-valve (TV) sensors, was discovered in which the nonmagnetic layer separating the two FM layers is made with an ultrathin nonconductive material, such as an aluminum oxide layer <20 Å thick. A distinctive feature of the TV sensor is its high impedance (>10 Σ−:m2), which allows for large signal outputs. A TV stack has two FM layers separated by a thin insulating tunnel barrier layer whose operation relies on the spin-polarized electron tunneling phenomenon known in the art. For low applied fields (<100 Oe), the pinned (reference) layer is essentially fixed in one direction because of, for example, a higher coercivity, than the free (sensing) layer, which is essentially free to rotate in response to external fields. The insulating tunnel barrier layer is thin enough so that quantum mechanical tunneling occurs between the two FM layers. The tunneling phenomenon is electron-spin dependent, making the magnetic response of the TV a function of the relative moment orientations and spin polarizations of the two FM layers. The TV stack operates with sense current-perpendicular-to-plane (CPP) of the layers.
Meanwhile, the functional integration of the semiconductor and the ferromagnet resulted in a new magneto-electronic device denoted the spin valve transistor (SVT). The SVT is a three-terminal device, analogous to a metal-base transistor, where the charge carrier populations are distinguished by spin (magnetic moment) instead of electrical charge. The metal SVT base, which includes a spin-selective element such as the CPP SV stack, is sandwiched between two N-type silicon layers, for example. Hot electrons are injected over a Schottky barrier from the SVT emitter into the SV stack. Those spin-oriented electrons that are not spin-scattered continue through the SV stack and traverse a second Schottky barrier at the SVT collector, forming the magnetocurrent, which is extremely sensitive to the spin-scattering in the SVT. The emitter and collector junction materials are usually selected to provide a higher Schottky barrier at the emitter junction (e.g., silicon-platinum) than at the collector junction (e.g., silicon-gold). Until recently, successful fabrication of such metal-silicon SVT junctions required growing the metal layers directly on the crystalline semiconductor surface because any oxide contamination at the junction suppresses the tunneling of spin-oriented electrons into the conduction band of the semiconductor, and inhibits interdiffusion. This means that two semiconductor wafers must be bonded face-to-face at some point during fabrication to complete the SVT stack. Spin-scattering of hot electrons is determined by the magnetic state of the SV stack, which is sensitive to the intensity and orientation of an external magnetic field. Thus, a SVT may be employed as a read sensor for magnetic data storage systems because of the resulting magnetocurrent sensitivity to external magnetic fields, which provides a relative magnetic response of over 300% at room temperature with small fields.
The first SVT was reported by Mark Johnson ("Bipolar Spin Switch," Science, Vol. 260, pp. 320–323, Apr. 16, 1993), who describes a basic device with no power gain and nanovolt signal levels. Johnson later describes a spin-injected field-effect transistor (FET) in U.S. Pat. No. 5,654,566. Subsequently, Monsma et al. ("Perpendicular Hot Electron Spin-Valve Effect in a New Magnetic Field Sensor: The Spin-Valve Transistor," Phys. Rev. Lett. Vol. 74, No. 26, pp. 5260–3, Jun. 26, 1995) describe the current-perpendicular-to-plane (CPP) SVT design now well-known in the art. Monsma et al. emphasize the importance of direct silicon-metal interfaces at the emitter and collector junctions, and propose a detailed method for direct semiconductor bonding through spontaneous adhesion of a gold bonding layer to join two silicon-metal Schottky junctions into a single SVT stack.
Later, Kumar et al. ("The Spin-Valve Transistor," J. Phys. D:Appl. Phys., Vol. 33, pp. 2911–20, November 2000) assert that it is essential to grow the metal layers directly on a crystalline silicon layer. They propose a vacuum metal-bonding method requiring clean room robots and a noble-metal bonding layer to join two processed wafers face-to-face during their SVT fabrication procedure. FIG. 1 shows the typical spin-valve transistor (SVT) embodiment 20 described by Kumar et al. A forward-biased emitter 22 having an emitter current IE and a reverse-biased collector 24 having a collector current IC each form a Schottky barrier with the base layer 26, which has a base current IB. The Si—Pt Schottky barrier 28 and the Si—Au Schottky barrier 30 are formed at emitter 22 and collector 24, respectively. Base layer 26, shown in detail, includes a NiFe/Au/Co SV stack 32. SVT 20 is fabricated by first building up all of the elements in base layer 26 on crystalline collector layer 24, using conventional thin-film techniques. Then a second crystalline silicon emitter layer 22 is bonded to base layer 26 at junction 28 using a sophisticated vacuum metal-bonding method. Once this surface bonding effort forms the platinum-to-platinum bonding layer 34, additional conventional thin-film fabrication steps may be employed to etch and mill emitter layer 22 to form a plurality of SVT structures exemplified by SVT 20. In FIG. 1, the magnetocurrent IM is shown passing through from emitter to collector and a current monitor in the emitter-base circuit measures a related sense current IS.
Other practitioners have proposed SVT fabrication methods that do not require a spontaneous adhesion bonding step. For example, in U.S. Pat. No. 5,973,334, Mizushima et al. employ a buffered nonmagnetic metal layer (e.g., aluminum) at the emitter to inject hot electrons into the SV stack (base) instead of using a Schottky barrier. This means that a single Schottky junction at the SVT collector is sufficient for SVT operation and no bonding step is needed to bond to an emitter Schottky junction for their SVT. In U.S. Pat. No. 6,218,718 B1, Gregg et al. describe a SVT wherein the pinned layer structure of the SV stack is separated by a silicon PN junction from a cobalt-oxide layer. Although Gregg et al. teach using a silver layer for the direct adhesion bonding step necessary for fabrication of one embodiment of their SVT design, they also suggest depositing a polysilicon layer at the collector to create an ohmic junction instead of a second Schottky junction. In this case, a single Schottky junction at the emitter is sufficient for SVT operation, and no bonding step is needed to bond to a collector Schottky junction for their SVT.
Clearly, the SVT is very useful as a read sensor for magnetic data storage systems because of its unusual sensitivity to external magnetic fields at room temperature and its small read width (RW) dimension. The SVT may be used as a read sensor in a magnetic read/write head for transferring data between a control circuit and a moving magnetic storage medium, such as a rotating magnetic disk or a streaming magnetic tape. Such a magnetic head is usually mounted on a slider at an air bearing surface (ABS) disposed at the moving surface of the magnetic medium. As is well-known, the slider is a key factor in determining the efficiency, density, speed, and accuracy with which data can be transferred and stored in a magnetic recording media in a data storage drive. The slider's size is an important performance factor; smaller sliders can effectively increase the recording medium's storage capacity by storing data more compactly on the recording medium. Functional integration is also an important performance factor. The typical slider merely includes a magnetic head to write and read binary data at a magnetic recording medium. However, some practitioners describe advanced slider designs that incorporate other circuitry to perform additional functions close to the read/write elements.
For example, in U.S. Pat. No. 4,809,103, Lazzari describes a silicon wafer having a magnetic head and an electronic circuit integrated to the head. As another example, Beck et al. (J. W. Beck & B. Brezoczky, "Magnetic Head Assembly Including Head Circuitry," IBM Technical Disclosure Bulletin, Vol. 22, No. 1, June 1979.) refer to a magnetic head assembly with input and output signal-processing circuitry incorporated in a chip fixed to an air bearing slider. The circuitry of Beck et al. appears to include read signal preamplifier and write signal output electronics. In addition to the improvement of signal-to-noise ratios for sensor signals, another benefit of disposing support circuitry aboard a slider is compactness. In modern data storage drives, element size is critical, especially in particularly compact applications such as data storage drives for laptop computers.
There is a clearly-felt need in the art for a monolithic slider that integrates a read/write head with an integral SVT and other signal-processing functions in a single element that may be fabricated using only those thin-film fabrication methods that are well-understood and widely-appreciated in the art. Until now, there was no method known in the art for fabricating a slider incorporating an integral SVT and other electronic components in a conventional thin-film process. The related unresolved problems and deficiencies are clearly felt in the art and are solved by this invention in the manner described below.

Semiconductor slider with an integral spin valve transistor structure and method for making same without a bonding step

Hitachi Global Storage Technologies Netherlands, B.V.


A zoom lens barrel includes a stationary cylindrical member, a rotatable cam ring and a linearly-guided member concentrically provided in that order from the outside of the zoom lens barrel, a first cam mechanism which is provided between the rotatable cam ring and the linearly-guided member to move the linearly-guided member in an optical axis direction without rotating upon rotation of the rotatable cam ring, and a second cam mechanism provided between the stationary cylindrical member and the rotatable cam ring to move the rotatable cam ring in an optical axis direction upon rotation of the rotatable cam ring. The second cam mechanism causes the rotatable cam ring to rotate while moving in the optical axis direction so that the amount of movement of the rotatable cam ring in the optical axis direction with respect to the angle of rotation thereof is nonlinear.

1. Field of the Invention
The present invention relates to a zoom lens barrel which includes a rotatable cam ring driven to rotate.
2. Description of the Related Art
In conventional zoom lens barrels, a moving mechanism, provided with a rotatable cam ring driven to rotate and having cam grooves, for linearly moving at least one linearly-guided member (generally a lens support frame), which is positioned radially inside the rotatable cam ring, in an optical axis direction by a rotational force of the rotatable cam ring has been widely adopted. The linearly-guided member is supported so as to be prevented from rotating in order to be capable of moving only linearly in the optical axis direction, and includes cam followers which are respectively engaged in the aforementioned cam grooves of the rotatable cam ring. In the case of such a mechanism having the simplest structure, two sets of cam grooves for moving two lens groups are formed on an inner peripheral surface of the rotatable cam ring while two sets of cam followers on two lens support frames of the two lens groups are engaged in the two sets of cam grooves, respectively, to thereby make it possible to give each of the two lens groups a predetermined zooming path.
The rotatable cam ring used to be rotated simply at a fixed position (i.e., without moving in the optical axis direction), however, in recently-produced zoom lens barrels including a rotatable cam ring, a structure in which the rotatable cam ring is engaged with a stationary ring via helicoids (helicoidal threads) and is rotated while being moved forward and rearward in the optical axis direction has been widely adopted to reduce the length of the zoom lens barrel when retracted. This type of zoom lens barrel is disclosed in Japanese Unexamined Patent Publication 2003-185907.
Nevertheless, in the conventional structure in which the rotatable cam ring rotates at a fixed position, if the length of the rotatable cam ring in the optical axis direction is short, the angle of inclination of each cam groove on the rotatable cam ring with respect to a circumferential direction thereof is great, which causes the rotatable cam ring to require a greater rotational force for rotating the rotatable cam ring. In addition, even in the conventional structure in which the rotatable cam ring moves forward and rearward in the optical axis direction while rotating via helicoids, the inclination of each cam groove on the rotatable cam ring with respect to a circumferential direction thereof is also great. Accordingly, such conventional structures, in which the inclination of each cam groove on the rotatable cam ring with respect to a circumferential direction thereof is great, narrows the degree of design flexibility of the zoom lens barrel and unnecessarily requires the rotatable cam ring to be long in length and have a long movement range.

Zoom lens barrel including a rotatable cam ring


This invention relates to a method and apparatus for image classification. More particularly, the present invention provides a technique to classify an image as a picture, a graphic or a mixed mode image. The classification is based on an approximation of a segmentation. The approximation is HVQ-LUT-based and outputs classification maps indicating whether pixels are background, text or pictures. Said classification maps are filtered to eliminate odd isolated samples and the resulting count of picture, text and background pixel is analyzed before concluding whether the image has pictorial, graphical or mixed contents.

This invention relates to a method and apparatus for image classification. More particularly, the present invention provides a technique to classify an image as a picture, a graphic or a mixed mode image. The classification is based on data accumulated as a result of an approximation of a segmentation process. In this regard, the approximation is HVQ-LUT-based and outputs classification maps indicating whether pixels are background, text or pictures. Said classification maps are optionally filtered to eliminate odd isolated samples and the resulting count of picture, text and background pixel is analyzed before concluding whether the image has pictorial, graphical or mixed contents.
While the invention is particularly directed to the art of image segmentation and classification, and will be thus described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications. For example, the invention may be used in any environment where it would be useful to clarify an image as a particular type.
By way of background, one technique utilized most typically in image processing operations is known as vector quantization (VQ). In VQ, a block of X×Y pixels is mapped to a single "codeword" which is defined using a smaller number of bits than the number required by the original block. Codewords are stored in transmitting, receiving and storage devices, and each codeword is associated with a pre-defined set of image data. The codeword to which each pixel block is mapped, is that codeword which is associated with image data that most closely matches the image data in the pixel block. The typical process includes mapping the pixel block to a codeword, storing the codeword or transmitting it to a receiving device, and then mapping the codeword back to image data when it is retrieved from storage or received at the receiving device. Since codebook storage and codeword transmission require less space and time than storage and transmission of original image data, this process greatly reduces the resources required to reproduce the original image data.
There are typically many more combinations of pixel blocks than there are available codewords, and as indicated by the term "quantization", several input blocks will be mapped to the same single given codeword. For a fixed number of codewords, increasing the size of the pixel block reduces the quality of mapping and reconstruction since a lot more of the actual image data must be mapped to the same number of codewords. Some drawbacks of VQ are that codebook design is often very complex, and that large amounts of time are usually required to search through the codebook and to match blocks to the appropriate codeword. While codebook design can be performed off-line, the block matching searches must be performed on-line.
In hierarchical vector quantization (HVQ), block matching searches are performed two samples at a time. Thus, look up tables (LUTs) can be used directly to perform HVQ in two or more stages. HVQ is described in U.S. Pat. No. 5,602,589, U.S. Pat. No. 6,470,052 B1 and Vishwanath and Chou, "An Efficient Algorithm for Hierarchical Compression of Video," Proc. ICIP-94, pages 275–279 (Nov. 13–16, 1994, all of which are incorporated herein by reference. Briefly, referring to FIG. 6, in the first stage of HVQ, two image pixels are mapped to one codeword, reducing the number of samples by a factor of 2. As shown, the number of samples is reduced form eight (8) to four (4) in stage 1. In the next stage (stage 2), the process is repeated to map pairs of codewords into single codewords. Preferably, codewords are grouped in a direction perpendicular to the direction used for the previous level. As the process continues (e.g. on to stage 3), the resulting codewords are mapped to larger and larger amounts of data.
HVQ allows for a rough approximation of the content of each image block by using simple look-up table operations. The final codeword represents a block approximation and can therefore be directly mapped to other quantities which describe certain characteristics of the approximated block, such as block activity. HVQ codebook design methods follow standard VQ codebook design algorithms and are usually performed by designing the codebooks for a single stage at a time.
In Anuradha Aiyer and Robert M. Gray ("Aiyer and Gray"), A Fast, Table-lookup for Classifying Document Images, Proc. of ICIP, Kobe, Japan, 25 PP4.10 (1999), which is incorporated herein by reference, a method to use HVQ to mimic the segmentation of an image is proposed. In this method, the HVQ output is correlated with the output of a segmentation process to assist in classifying portions of an image as picture, background, or text.
Further, in Hui Cheng and Charles A. Bouman ("Cheng and Bouman"), Trainable Context Model for Multiscale Segmentation, Proc. of IC IP, Chicago, Ill., pp. 610–614 (1998), which is incorporated herein by reference, a segmentation method to classify image regions as text, background or picture regions is disclosed. Classification is performed through Bayesian training allied with some multiresolution analysis. It performs segmentation and classifies image pixels as BACKGROUND (B), TEXT (T) or PICTURE (P).
Briefly, the Cheng and Bouman segmenter ("CBS") works by using binary classification trees to model the transition probabilities between segmentations at adjacent scales. The classification trees can be efficiently trained to model essential aspects of contextual behavior. In addition, the data model in the approach can incorporate the correlation among the wavelet feature vectors across scales.
The present invention contemplates a new and improved technique for image classification that allows for an efficient classification of an input image.

Method and apparatus for image classification


The global proliferation of high speed communication networks has created unprecedented opportunities for geographically distributed resource interaction. A crowd sourced project management synthesizer provides crowd sourced project management features, as well as resource performance tracking features, to provide efficiencies to the project's implementation.

The global proliferation of high speed communication networks has created unprecedented opportunities for geographically distributed resource interaction. However, while the opportunities exist and continue to grow, the realization of those opportunities has fallen behind, and new technical problems arise from the utilization of the geographically distributed resources. In part, this is due to the technical challenges that arise when connecting the geographically distributed resources together as part of a team of crowd sourced resources in an effective operational environment to accomplish a common project.

Crowd sourced resources as selectable working units


The applicator includes a frame assembly, a plurality of wheels attached to this frame assembly, a spindle assembly supported by the frame assembly, and a plurality of stress-relief rollers. The frame assembly includes left and right side support assemblies which include respective left and right side handle assemblies. Elongated support elements secure the left side support assembly to the right side support assembly. The wheels moveably support the frame assembly relative to the roof. The spindle assembly is supported by the left and right side support assemblies. The spindle assembly is capable of holding a spool of roofing felt. The stress-relief rollers extend between the left and right side support assemblies. When an operator desires to apply roofing felt, roofing felt is dispensed from the spool of roofing felt and is directed serially through the plurality of stress-relief rollers so as to relieve stress in the roofing felt prior to its application to the roof. An adhesive material dispenser assembly is attached to the frame assembly for dispensing adhesive material as the roofing felt is being applied. The applicator includes a final roller/segmented outfeed roller assembly operably attached to the frame assembly. When an operator desires to apply roofing felt, felt is dispensed from the spool of roofing felt and is directed under a segmented roller of the final roller/segmented outfeed roller assembly for providing enhanced urging of the roofing felt against the roof in a manner that compensates for roof surface irregularities.

The present invention relates to cold process roof application, and more particularly to a cold process roofing felt applicator for efficiently creating a multi-ply membrane on a roof.
As background, when roofers are typically installing a cold process roof membrane they first attach a base ply (i.e. roofing felt) over the insulation, existing roof membrane or designated substrate. The base applied may be fiberglass, polyester, organic material, modified bitumen or other roofing felt material. The roofers then hand spray adhesive material (e.g. an asphalt cold process material) to the base ply. They then hand lay roofing felt over the adhesive and then hand broom or squeegee another layer of cold process adhesive over that first layer of roofing felt. Over that cold process adhesive they then lay an additional layer of roofing felt. This built up roofing felt/cold process adhesive may comprise several layers and is currently typically done manually.
Others have addressed problems inherent in the hot process application of roofing materials with various dispensing systems. For example U.S. Pat. No. 4,869,044, issued to R. D. Wald discloses a method of applying heated roofing paper. U.S. Pat. No. 4,761,201, issued to S. C. Nichols, Jr., discloses a self-contained apparatus to guide a roll of roofing material, to heat the departing roofing material, and to sealably lay the heated roofing material on a roof surface. U.S. Pat. No. 5,213,278, issued to J. V. Holback et.al., describes an apparatus for applying web shaped material to a substrate.
U.S. Pat. No. 4,725,328, issued to W. Arnold, discloses a single ply roofing applicator with a heater. U.S. Pat. No. 4,460,433, issued to W. K. Boyd, discloses a pressure roller for roofing machines.
It is therefore a principal object of the present invention to automate the cold process roofing felt application process.
It is another object to efficiently relieve stress in the roofing felt prior to its application to the roof.
It is yet another object to provide enhanced urging of the roofing felt against the roof in a manner that compensates for roof surface irregularities.
These and other objects are achieved by the present invention which is a cold process roofing felt applicator. In one broad aspect, the applicator includes a frame assembly, a plurality of wheels attached to this frame assembly, a spindle assembly supported by the frame assembly, and a plurality of stress-relief rollers. The frame assembly includes left and right side support assemblies which include respective left and right side handle assemblies. Elongated support elements secure the left side support assembly to the right side support assembly. The wheels moveably support the frame assembly relative to the roof. The spindle assembly is supported by the left and right side support assemblies. The spindle assembly is capable of holding a spool of roofing felt. The stress-relief rollers extend between the left and right side support assemblies. When an operator desires to apply roofing felt, roofing felt is dispensed from the spool of roofing felt and is directed serially through the plurality of stress-relief rollers so as to relieve stress in the roofing felt prior to its application to the roof.
In a more narrow aspect, the applicator includes an adhesive material dispenser assembly attached to the frame assembly for dispensing adhesive material as the roofing felt is being applied.
In another broad aspect, the applicator includes a frame assembly, a plurality of wheels attached to the frame assembly, a spindle assembly, and a final roller/segmented outfeed roller assembly operably attached to the frame assembly. When an operator desires to apply roofing felt, felt is dispensed from the spool of roofing felt and is directed under a segmented roller of the final roller/segmented outfeed roller assembly for providing enhanced urging of the roofing felt against its substrate in a manner that compensates for roof surface irregularities.
The present invention utilizes pressure supplied adhesive rather than gravity supplied/fed adhesive. This provides uniform adhesive spray coverage.
Other objects, advantages, and novel features will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.


A transceiver system and method in an OFDM communication system which enables exact symbol synchronization acquisition and improves performance for frequency offset and channel estimation. In the apparatus, a guard interval filling unit copies data at a predetermined interval in an input data row inputted to be transmitted, and fills in the copied data in the preset guard interval in the input data row. A selection unit selectively receives an output data row outputted from the guard interval filling means and unique words having a constant amplitude and a non-periodic auto-correlation characteristic, and outputs the OFDM symbol in which the unique words are inserted in the output data row.

1. Field of the Invention
The present invention relates to a communication system employing an Orthogonal Frequency Division Multiplexing (hereinafter, referred to as 'OFDM') technique, and more particularly to an apparatus and method for generating an OFDM symbol in which a guard interval is inserted.
2. Description of the Related Art
In general, data are carried by a predetermined carrier when the data are transmitted by a wireless communication system. Further, in order to transmit data by means of a predetermined carrier, it is necessary to modulate the data. Such modulation may employ various techniques, one representative of which is an OFDM technique.
The OFDM technique is a modulation technique of 4th Generation Mobile Communication Systems, which it is anticipated being adopting as a digital television standard in Europe, Japan, and Australia, and which was initially recommended as a wireless LAN technique in the early 1990's. According to the OFDM technique, data are distributed to a plurality of carriers spaced at regular frequency intervals from each other, each at an exact frequency, thereby preventing any particular decoder receiving the data from referring to other frequencies which are not transmitted to that particular decoder, that is, providing "orthogonality" among different signals.
The modulation schemes for carriers employed in OFDM systems include multiplexing modulation schemes such as QPSK (Quadrature Phase Shift Keying) for voice broadcasting and 64 QAM (Quadrature Amplitude Modulation) for ground wave digital television broadcasting (which has good band use efficiency). OFDM systems use different modulation schemes according to the characteristics described above. However, in OFDM communication systems, data are transmitted by units based on OFDM symbols regardless of the modulation schemes. Each of the OFDM symbols used in the OFDM communication systems includes an effective symbol interval and a guard interval. Herein, the guard interval is a signal interval for reducing multipath effects or ghost phenomena.
In a system employing the OFDM technique, N pieces of parallel data to be transmitted are carried on N sub-carriers having orthogonality to each other, so that the parallel data are multiplexed. Thereafter, the multiplexed data are summed and transmitted. Herein, when the N pieces of parallel data construct an OFDM symbol, the orthogonality among the N sub-carriers in the OFDM symbol prevents interference among the sub-carrier channels. Therefore, in comparison with an pre-existing single carrier transmission technique, the OFDM technique can increase the symbol period by a factor of the number N of the sub-carrier channels while maintaining the same symbol transmission rate.
Further, in the case of increasing the periods of transmitted symbols and inserting guard intervals between the symbols, the guard intervals can prevent multipath delay or interference between symbols which may be caused by delay of the symbols received through the multipaths and can maintain the orthogonality between the sub-carriers. Moreover, interference among channels, which may be caused by decrease of the orthogonality among the sub-carriers, can be reduced.
A reception terminal for receiving the OFDM signal can perform synchronization by means of the guard intervals inserted among the symbols. The OFDM synchronization includes synchronization for acquiring symbol time offset and synchronization for acquiring frequency offset. Beginning points of the OFDM symbols are estimated in the synchronization for acquiring symbol time offset, and degree of frequency offset of OFDM sub-carriers is estimated in the synchronization for acquiring frequency offset.
In synchronization acquisition utilizing a guard interval of an OFDM symbol, there is a correlation between samples in a guard interval and samples copied to generate the guard interval. Therefore, in a symbol, a position where a correlation value between a guard interval and an interval copied for the guard interval becomes maximum can be considered as the beginning of the guard interval. Usually, after synchronization acquisition is completed utilizing a guard interval, frequency offset is estimated using the acquired information. When the synchronization process for acquiring the frequency offset of the received OFDM symbol is not exact, loss of effective data cannot be prevented. This correlation eliminates the necessity of a pilot symbol in channel estimation. Therefore, the OFDM technique as described above can improve bandwidth efficiency and reduce power consumption.
Due to the reasons described above, OFDM wireless communication systems which employ a technique for inserting guard intervals are being developed in fields requiring high speed data transmission systems, such as Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB), Digital Terrestrial Television Broadcasting (DTTB), Wireless Local Area Network (WLAN), and Wireless Asynchronous Transfer Mode (WATM). Also, digital wire communication systems employing a Discrete Multi-Tone (DMT) technique, such as Asymmetric Digital Subscriber Line (ADSL) and Very-high bit rate Digital Subscriber Line (VDSL), necessarily require the technique for inserting guard intervals.
FIG. 1 is a block diagram of a typical OFDM communication system, and shows channel environment as well as blocks of a transmitter and a receiver.
Referring to FIG. 1, the OFDM transmitter 110 includes a mapper 111, a serial-to-parallel (S/P) converter 112, an N-point Inverse Fast Fourier Transform (IFFT) device 113, a Parallel-to-Serial (P/S) converter 114, a guard interval inserter 115, and a digital-to-analog (D/A) converter 116.
The data source to be transmitted is inputted to the mapper 111 of the transmitter 110. The data inputted to the mapper 111 are modulated according to a modulation scheme adopted in each system and then inputted to the S/P converter 112. The S/P converter 112 converts the modulated serial data into N pieces of parallel data xl(k) and then inputs the converted parallel data to the IFFT device 113. Then, the IFFT device 113 performs Inverse Fourier Transform for the N pieces of parallel data and then inputs them to the P/S converter 114. The P/S converter 114 converts the Inverse Fourier Transformed data into serial data xl(n) and inputs the converted serial data to the guard interval inserter 115. The guard interval inserter 115 inserts a guard interval in the data from the P/S converter 114, thereby converting the data xl(n) into data {tilde over (x)}l(ñ) which construct an OFDM symbol. The OFDM symbol outputted from the guard interval inserter 115 in this way is converted into an analog signal in the D/A converter 116, which is then transmitted through a predetermined wireless channel.
The wireless channel through which the OFDM symbol generated through the above-described process is transmitted is a multipath channel 120. When the multipath channel 120 is assumed to be a function Hl(k), the outputted OFDM symbols can be considered as values obtained by calculation using the function. Further, when noise generated in the channel environment is assumed to be {tilde over (w)}l(ñ), the signal received by the receiver has a value obtained by adding the generated noise to the value obtained by the function.
The receiver 130 includes an analog-to-digital (A/D) converter 131, a guard interval remover 132, a serial-to-parallel (S/P) converter 133, an N-point Fast Fourier Transform (FFT) device 134, an equalizer 135, a synchronization and channel estimation device 136, a parallel-to-serial (P/S) converter 137, and a demapper 138.
The received signal to which noise is added while passing the multipath channel 120 is inputted to the A/D converter 131. The A/D converter 131 converts the received analog signal into a digital signal of the form {tilde over (y)}l(ñ) and then outputs the converted digital signal. The digital signal outputted from the A/D converter 131 is inputted to the guard interval remover 132. The guard interval remover 132 removes the guard interval from the inputted digital signal {tilde over (y)}l(ñ) and then outputs a signal in a form of yl(n). That is to say, the signal from which the guard interval has been removed by the guard interval remover 132 includes only the effective OFDM data. The effective OFDM data are inputted to the S/P converter 133. The S/P converter 133 parallelizes the inputted signal and then outputs the parallelized data to the FFT device 134. The FFT device 134 performs an N-point Fast Fourier Transform (FFT), thereby outputting Fast Fourier Transformed parallel data yl(k).
The Fast Fourier Transformed parallel data are inputted to, are channel-equalized in, and are then outputted as a signal such as {circumflex over (X)}l(k) from, the equalizer 135. The signal outputted from the equalizer 135 is inputted to the P/S converter 137. The P/S converter 137 converts the inputted parallel signal into a serial signal and then outputs the serial signal. The converted serial signal is inputted to and demodulated in the demapper 138, so that complete data can be extracted from the signal. Further, the synchronization and channel estimation device 136 acquires symbol synchronization and performs channel estimation for establishing some parameters of the equalizer 135.
During the process described above, when the guard interval inserter 115 inserts the guard interval, the guard interval inserter 115 inserts a Cyclic Prefix (CP), which is longer than the channel impulse response, in a guard interval position between adjacent OFDM symbols, thereby eliminating interference between adjacent symbols and interference between channels.
FIG. 2 illustrates a construction of an OFDM symbol in which a guard interval is inserted according to a conventional CP method.
Referring to FIG. 2, in order to maintain the orthogonality between sub-channels, a guard interval including Tc a number of samples is located before effective data including a number T of samples. In this case, the Tc samples of the guard interval 20 are produced by copying Tc samples 21 to the rear portion of the effective data, which corresponds to the location of the guard interval. Therefore, the size in samples of the OFDM symbol is a sum of Tc, which is the number of samples constituting the CP or guard interval, and T, which is the number of samples constituting the effective data. In this method, Inverse Fast Fourier Transformed effective data (T number of samples) are inputted in series only after a delay corresponding to a sample size (Tc samples) sufficient to allow insertion of the guard interval, and then the rear portion of the effective data is copied as a CP to the delayed interval. Therefore, a delay device (buffer) as many as the FFT/IFFT size T, a memory, or a memory address generator is indispensable and an initial delay of Tc is caused in this method.
For synchronization acquisition in the symbol realized as in FIG. 2, beginning synchronization of the symbol is acquired by performing correlation between the CP during the guard interval Tc and the symbol interval copied to generate the CP, that is, correlation between the guard interval 20 and the copied effective interval 21 in FIG. 2. In this case, a reception terminal must know an exact Signal to Noise Ratio (SNR) for the synchronization acquisition. In other words, if the reception terminal cannot calculate a sufficiently exact SNR, exact synchronization acquisition for the symbol cannot be anticipated and thus frequency offset estimation based on exact synchronization acquisition is impossible.

Apparatus and method for guard interval inserting/removing in an OFDM communication system


A hand exercise device comprising a base with a generally planar surface, and at least one string held at a substantial angle of inclination with respect to the planar surface of the base. The hand exercise device can be adapted to perform hand exercises that involve applying a pushing force to move the string such that the string is in contact with the planar surface of the base. The hand exercise device can be modified to include a plurality of strings of different thicknesses held at a substantial angle of inclination to facilitate variable exercise resistance. The hand exercise device can benefit patients by increasing grip strength, improving hand function, and/or alleviating joint pain.

Arthritis is a public health challenge, affecting approximately 50 million people in the United States. Arthritis has been the most common cause of disability in the United States for the past 15 years and costs the U.S. economy an estimated $128 billion annually. Rheumatoid arthritis is a systemic disease characterized by inflammation of membranes that line joints and is accompanied by severe pain and joint damage. Osteoarthritis is the most common form of arthritis and is characterized by progressive breakdown of joint cartilage. Osteoarthritis often results in degenerative damage to joints of the hand. Endurance and resistance types of exercise have been shown to provide considerable disease-specific benefits for people with osteoarthritis and rheumatoid arthritis. Muscle strengthening exercises can help support the joints, improve function and/or joint pain, and facilitate maintaining bone strength without hurting the joints.
Users can improve strength, function, and/or joint pain in their hands by performing endurance and resistance types with a hand exercise device. An example hand exercise device may include a compressible surface such as a sphere made of a flexible material such as polyurethane, neoprene, silicone, or latex. A user holds the exercise device in their palm to apply a compressive force on the surface of the sphere. The sphere offers resistance to the compressive force applied by the user because of elastic properties of the material of the sphere. The exercise comprises repetitive application and removal of the compressive force on the surface of the sphere.
Another example of a hand exercise device may include compression springs instead of or in addition to a natural or engineered surface that offers resistance against a compressive force due to material elastic properties. One or more compression springs may be supported by a surface. A second surface may be supported by the compression springs. A user may apply a compressive force to perform hand exercises. The compression springs offer resistance to the applied compressive force. The exercise may comprise a specific number of repetitions of applying the compressive force on the surface. The user may disassemble the hand exercise device and replace the compression springs with another set of compression springs that offer more or less resistance to the applied compressive force.
Another example of a hand exercise device may include bands made of a polymer with elastomeric properties such as neoprene, silicone or latex supported by two support posts. One of the support posts is fixed, while the other support post may be moved by applying a tensile or pulling force on the support post. The movable support post transfers the applied pulling force to the elastomeric bands which may offer resistance to the applied pulling force. The exercise may comprise applying the pulling force on the movable support post for a specific number of repetitions.
Hand exercise devices that do not offer variable exercise resistance and precise finger flexion may not result in measurable improvement in joint strength and pain reduction. Hand exercise devices that include variable exercise resistance may have many parts and components that must be disassembled to replace the parts that offer exercise resistance. Such hand exercise devices may not encourage the user to exercise regularly. Disassembly of parts and replacement of exercise surfaces may also increase the cost of the hand exercise devices. Hand exercises that include applying a precise force using specific areas of the hand offers muscle flexion and can improve finger and hand strength while mitigating joint pain. Such exercises may be more beneficial than exercises that involve pushing or squeezing a compression surface because of the precision involved in applying a pushing force on a string, as opposed to an exercise surface.


This invention relates to improved blood contact devices such as vascular prostheses rendered antithrombotic through the use of recipient endothelial cells grown on an appropriate subendothelial matrix. The subendothelial matrix layer, which serves as the substratum for growing endothelial cells, may be obtained from either natural donor vessels or from in vitro tissue culture sources. This subendothelial matrix is used in situ on the donor vessel, or is grown or applied to a synthetic component, preferably porous expanded polytetrafluoroethylene. Once this subendothelial matrix is prepared, recipient endothelial cells are seeded onto this matrix substratum, which then serves as the immediate blood contact surface. The endothelial cells may be applied as an intra-operative procedure, or grown on the subendothelial matrix substratum in vitro until the cells establish a confluent monolayer. A key aspect of this invention is that living, recipient endothelial cells are grown on the appropriate subendothelial matrix substratum, thereby providing a substantially nonthrombotic blood contact surface. Furthermore, the likelihood of recipient immunological response is minimized. This invention results in vascular prostheses that are particularly useful for arterial bypass requiring a diameter of 6 mm or less.

1. Field of the Invention
The present invention relates to improved blood contact surfaces for use in apparatus such as in artificial blood vessels and other implantable appliances and methods for producing the blood contact surfaces.
2. Description of Related Art
Synthetic materials are widely used to replace diseased or damaged portions of the human cardiovascular system. The use of grafts composed of synthetics such as polyethylene terephthalate and expanded polytetrafluoroethylene (ePTFE), has provided successful results in the replacement of large vessels such as the aorta, iliac, or femoral arteries. The application of these same synthetics, however, to small diameter arteries such as in coronary artery bypass or peripheral arterial bypass beyond the popliteal artery often produces thrombosis despite patency-enhancing pharmacological measures. Other applications of synthetics in which clot formation is a frequent problem include the replacement of veins, heart valves, and the artificial heart. Tissue-based prosthetics provide similar performance to synthetics, having acceptable function in some applications, but in others, still having the complication of thrombus formation. These thrombotic problems limit the usefulness of both tissue-based and synthetic devices, particularly in more demanding applications. Consequently, a goal of researchers for many years has been to develop a blood contact surface that provides for the reduction or elimination of thrombosis.
Natural blood contact surfaces, such as those found within blood vessels, possess mechanisms that prevent blood from clotting during normal passage along the surface. In the case of a mammalian artery, the immediate blood contact surface comprises a layer of non-thrombogenic endothelial cells (ECs). Immediately external to the endothelial cell layer is the remainder of the intima: a subendothelial matrix layer of basement membrane and underlying glycoprotein-bearing extracellular matrix, and the internal elastic lamina. Surrounding the intima layer is the multilaminate media structure containing smooth muscle cells (SMCs) and elastin, and surrounding this media is the adventitia, the most external layer comprised of fibroblasts and connective tissue. Both the subendothelial layer and media are generally considered to be thrombogenic in nature in order to maintain hemostasis when the vascular system is injured.
Intact endothelial linings are considered to be non-thrombogenic unless damaged. Because of their blood-contacting location, endothelial cells have been thoroughly investigated with respect to their anti-thrombogenic function. Endothelial cells are known to synthesize or bind a number of substances with coagulation-inhibiting or fibrinolytic function including heparan sulfate/antithrombin III, dermatan sulfate/heparin cofactor II, thrombomodulin/protein C/protein S, prostacyclin and tissue-type plasminogen activator. Furthermore, segments of endothelium-bearing autologous vessel transplanted from one site to another in an individual to bypass diseased vessels exhibit an incidence of thrombosis substantially less than that of synthetics used in the same application. For these reasons, it has been assumed that endothelial cells are responsible for the non-thrombogenic activity of vessels. According to this assumption, synthetic blood contact devices capable of thrombo-resistance similar to the native vasculature would require a blood contact surface of endothelial cells.
Numerous attempts have been made to provide prosthetic surfaces, and specifically vascular grafts, that include or develop an endothelial cell lining. The overwhelming majority of these attempts have been carried out as an intraoperative cell-seeding procedure. Intraoperative cell-seeding typically involves harvesting endothelial cells from the recipient during the procedure and immediately seeding these collected cells onto a vascular graft that has been pretreated with a substrate to enhance endothelial cell attachment. Substrates frequently applied to the synthetic surface include preclotted blood taken from the patient or extracellular matrix proteins such as fibronecfin, collagen, or laminin, either singly or in combination. This approach was first reported by M. B. Herring et al. in "A single staged technique for seeding vascular grafts with autogenous endothelium," Surgery 84:498-504 (1978). In this procedure, autologous cells were seeded onto a preclotted DACRON.RTM. graft. These seeded grafts demonstrated a decreased thrombus formation compared to control grafts without endothelial cells. In spite of the improved initial adherence of the cells to the synthetic surface afforded through the use of these various substrata, the shear forces resulting from blood flow nevertheless leads to the loss of a substantial fraction of the applied cells.
In a variation of the above, U.S. Pat. No. 4,960,423 to Smith describes the use of elastin-derived peptides to enhance endothelial cell attachment. Some studies have used combinations of extracellular matrix molecules and cells to provide a substrate for endothelial cell attachment and growth. For example, U.S. Pat. Nos. 4,539,716 and 4,546,500 to Bell describe means by which endothelial cells are grown on a living smooth muscle cell-collagen lattice. In addition, U.S. Pat. No. 4,883,755 to Carabasi et al. describes a technical method for seeding endothelial cells onto damaged blood vessel surfaces.
Alternative means of growing endothelial cells on vascular grafts have also been reported. For example, the use of physical force to apply endothelial cells to graft surfaces is described in U.S. Pat. No. 5,037,378 to Muller et al. In another example, U.S. Pat. No. 4,804,382 to Turina and Bittman describe the application of endothelial cells to a semi-permeable membrane in which the pores are filled with aqueous gels to allow endothelial cell coverage.
Another approach has been the seeding of endothelial cells onto biologically-derived surfaces, including pericardium, cardiac valve leaflets, amnion, and arteries. These efforts appear to have originated with J. Hoch et al. in "In vitro endothelialization of an aldehyde-stabilized native vessel," J. Surg. Res. 44:545-554 (1988), where the authors attempted to grow endothelium on ficin-digested, dialdehyde stabilized, bovine artery. Human venous endothelial cells were found to adhere to and spread on the remnant collagen surface of these enzyme-digested grafts, but no implant studies were performed. J. Hoch et al. also investigated the growth of endothelium on human amnion, on live, mechanically-scraped human artery, and again on ficin-digested, tanned bovine artery. (J. Hoch et al., "Endothelial cell interactions with native surfaces," Ann. Vasc. Surg. 2:153-159 (1989)) Although endothelial cell adhesion was observed on these surfaces by 2 hours, the longterm persistence of ECs on these surfaces was not examined, and, as in the previous study, none of these endothelialized materials were implanted as vascular substitutes. P. A. Schneider et al. showed that endothelial cells could be successfully seeded onto the remaining collagenous surface of baboon vessels from which the intima was removed. (P. A. Schneider et al., "Confluent durable endothelialization of endarterectomized baboon aorta by early attachment of cultured endothelial cells," J. Vasc. Surg. 11:365-372 (1990)) S. G. Lalka et al. used detergent extraction of canine arteries to produce an ethanol-fixed acellular vascular matrix onto which human umbilical vein endothelial cells were successfully seeded in vitro. (S. G. Lalka et al., "Acellular vascular matrix: A natural endothelial cell substrate," Ann. Vasc. Surg. 2:108-117 (1989))
In a study similar to that of Hoch et al. in J. Surg. Res., supra, L. Bengtsson et al. successfully grew human venous endothelium on the luminal surface of devitalized vessel segments denuded of endothelium and subendothelium. (L. Bengtsson et al., "Lining of viable and nonviable allogeneic and xenogeneic cardiovascular tissue with cultured adult human venous endothelium," J. Thorac. Cardiovasc. Surg. 106:434-443 (1993))
It is emphasized that in none of the foregoing studies have attempts to provide endothelial linings to biological tissues been carried out on tissues with an intact subendothelium. Furthermore, in none of these attempts have the tissues been tested as chronic vascular substitutes following endothelialization.
Biological tissues destined for implant use are commonly subjected to a preservation treatment employing fixative agents such as glutaraldehyde, formaldehyde, dialdehyde starches, polyepoxy compounds, or alcohols. Glutaraldehyde is the most commonly used crosslinking agent because it provides reduced immunogenicity, excellent tissue preservation, and stability in the implant environment. The use of glutaraldehyde as an agent to produce articles derived from biological tissues suitable for implantation is specified in a number of U.S. Patents, including U.S. Pat. Nos. 3,562,820 to Braun, 3,966,401 to Hancock et al., 3,988,782 to Dardik, 4,050,893 to Hancock et al., 4,098,571 to Miyata et al., 4,323,358 to Lentz et al., and 4,378,224 to Nimni et al. Although glutaraldehyde-treated tissues have generally provided good implant outcome, it has been shown that unreacted, residual glutaraldehyde can result in the inhibition or death of cells grown in contact with the fixed tissue. Previous investigators (see, for example, L. Bengtsson et al. supra) have shown that growth of endothelium on fixed tissue can be inhibited by residual glutaraldehyde.
The problem of residual glutaraldehyde has been addressed by blocking the reactive site on the aldehyde groups. It is well known that residual or free aldehyde groups can be effectively blocked using compounds containing amino groups such as amino acids or proteins. Grimm et al. ("Glutaraldehyde affects biocompatibility of bioprosthetic heart valves," Surgery 111:74-78 (1992)) describe a postfixation treatment by which reactive aldehyde groups can be passivated. Endothelial cell-seeded, glutaraldehyde-fixed tissue showed uninhibited cell growth following a 48 hour exposure to 8% L-glutamic acid. Nashef et al., in U.S. Pat. No. 4,786,287, specify the use of solutions containing an excess of aldehyde-reactive amines to increase the rate of aldehyde diffusion from fixed tissue by maintaining a low concentration of free aldehyde. U.S. Pat. No. 4,553,974 to Dewanjee describes another method to prepare collagenous tissues for endothelialization using a surfactant-detergent treatment, followed by glutaraldehyde fixation and anti-calcification treatments. Although endothelium has been previously grown on tissue surfaces, the treatments employed, including ficin digestion, detergent treatment, and mechanical removal, each disrupt the subendothelial layer, resulting in increased thrombogenicity. Additionally, tissues such as pericardium or amnion do not, in the native state, possess the required subendothelial matrix.
Recent efforts to provide a substrate that supports endothelial cell linings on graft surfaces include the use of in vitro cultured extracellular matrix. A. Schneider et al. used corneal endothelial cells to produce extracellular matrix on ePTFE vascular grafts. (A. Schneider et al., "An improved method of endothelial seeding on small caliber prosthetic vascular grafts coated with natural extracellular matrix," Clin. Mat. 13:51-55 (1993)) After production of an extracellular matrix, these original cells were then removed using Triton X-100 and NH.sub.4 OH, and the tubes were seeded again with bovine aortic endothelium. This approach showed that endothelium could be successfully grown on the extracellular matrix lining the ePTFE grafts, however, no implant studies were performed. Another approach by Y. S. Lee et al. employed fetal human fibroblasts in culture to secrete extracellular matrix onto a polyurethane tube. The fibroblast cells were then removed by one of several methods and the remaining matrix seeded with human omental endothelial cells. This method resulted in a patent graft at 5 weeks after implantation into a rat aorta. (Y. S. Lee et al., "Endothelial cell seeding onto the extracellular matrix of fibroblasts for the development of a small diameter polyurethane vessel," ASAIO Journal 39:M740-M745 (1993))
A similar approach has also been taken by H. Miwa et al., "Development of a hierarchically structured hybrid vascular graft biomimicking natural arteries," ASAIO Journal 39:M273-77 (1993). In this case, smooth muscle cells are layered over a DACRON.RTM. graft in an applied artificial matrix of collagen type I and dermatan sulfate glycosaminoglycan. A layer of endothelial cells is then grown on the artificial matrix to serve as the blood contact surface.
Since the endothelium is the acknowledged source of the antithrombotic behavior of the normal vasculature, an endothelial lining has been widely regarded as the means by which improved antithrombogenicity of cardiovascular implants will be achieved. Actual testing however, has provided mixed outcomes. A number of studies have been conducted in animals, with some reporting clear improvements in patency as a consequence of endothelialization. Several studies, though, report equivocal outcomes with little measurable improvement. (P. Zilla et al., "The endothelium: A key to the future," J. Card. Surg. 8:32-60 (1993)) P. Ortenwall et al., for example, showed similar patency outcomes between seeded and control grafts in both sheep and dogs. (P. Ortenwall et al., "Seeding of ePTFE carotid interposition grafts in sheep and dogs: species dependent results," Surgery 103:199-205 (1988))
Although the collective results of experimental seeding studies conducted in animals are suggestive of a performance improvement due to the addition of recipient endothelial cells, the data do not indicate a performance improvement to the level expected with the use of the autologous vessel. For example, in a test conducted in sheep, N. L. James et al. report that only one of six (1/6) endothelial cell seeded grafts was patent in comparison to six of six (6/6) autologous artery grafts. (N. L. James et al., "In vivo patency of endothelial cell-lined expanded polytetrafluoroethylene prostheses in an ovine model," Artif. Org. 16:346-53 (1992)) Similarly, application of the above described endothelialization methods to synthetic vascular implants in humans has shown little demonstrable improvement in patency, despite the observation that grafts seeded with recipient cells become endothelialized, at least in some cases. (P. Zilla et al., "The endothelium: A key to the future," J. Card. Surg. 8:32-60 (1993)) Thus, the actual clinical outcome achieved with endothelial-lined synthetics has not met the expectations raised by animal studies.

Blood contact surfaces using endothelium on a subendothelial matrix


The present disclosure provides a sound device, which includes a magnetic circuit system, wherein the magnetic circuit system includes a bottom plate, a first magnetic portion arranged on the bottom plate and a second magnetic portion spaced apart from the first magnetic portion, at least one of the first magnetic portion and the second magnetic portion is a permanent magnet, the bottom plate is provided with a through hole penetrating through the bottom plate, the sound device further includes a damping member, the damping member is fixed on the bottom plate and completely covers the through hole, and the permanent magnet is at least partially abutted against the damping member.

With an advent of a mobile Internet era, the number of intelligent mobile devices is increasing. Among numerous mobile devices, a mobile phone is undoubtedly the most common and portable mobile terminal device. At present, the mobile phone has extremely diverse functions, one of which is a high-quality music function. Therefore, a sound device for playing sound is widely used in current intelligent mobile devices.
An important factor affecting performance of the sound devices is a damping effect, so that various frictions and other blocking effects attenuating free vibration are called damping. A good application of damping can improve a frequency response characteristic and improve acoustic performance of the sound device.
The sound device in related technologies includes a basket, a vibration system fixed to the basket and a magnetic circuit system driving the vibration system to vibrate. The vibration system may compress air in an inner cavity of the sound device while vibrating. Therefore, an electroacoustic device is provided with a leakage hole, and a damping sheet is attached to the leakage hole and the damping sheet plays a role of dust prevention and sound resistance improvement. However, under a condition of a small external space, the structure is easy to cause blockage of the leakage hole, thus affecting the acoustic performance of products. And the damping sheet is arranged to cover the leakage hole, manual bonding procedures need to be added outside an automatic line during assembly, and in addition, there is a risk of failure and falling of the damping sheet in related environmental tests of finished products, which affects the product performance. Therefore, it is necessary to provide a new sound device to solve the technical problems above.

AAC Acoustic Technologies (Shenzhen) Co., Ltd.


Novel polymerizable ester compounds having formulae (1) to (4) undergo no acid-induced decomposition by β-elimination wherein A1 is a polymerizable functional group having a carbon-carbon double bond, R1 is H or —C—(R5)3, R2 and R3 are alkyl, R4 is H or alkyl, R5 is a monovalent hydrocarbon group, X is alkylene, Y is methylene, ethylene or isopropylidene, Z is alkylene, and n=1 or 2. Resist compositions comprising polymers derived from the ester compounds have excellent sensitivity and resolution and lend themselves to micropatterning lithography.

In the drive for higher integration and operating speeds in LSI devices, the pattern rule is made drastically finer. The rapid advance toward finer pattern rules is grounded on the development of a projection lens with an increased NA, a resist material with improved performance, and exposure light of a shorter wavelength. In particular, the change-over from i-line (365 nm) to shorter wavelength KrF laser (248 nm) brought about a significant innovation, enabling mass-scale production of 0.18 micron rule devices. To the demand for a resist material with a higher resolution and sensitivity, acid-catalyzed chemical amplification positive working resist materials are effective as disclosed in U.S. Pat. No. 4,491,628 and U.S. Pat. No. 5,310,619 (JP-B 2-27660 and JP-A 63-27829). They now become predominant resist materials especially adapted for deep UV lithography.
Resist materials adapted for KrF excimer lasers enjoyed early use on the 0.3 micron process, passed through the 0.25 micron rule, and currently entered the mass production phase on the 0.18 micron rule. Engineers have started investigation on the 0.15 micron rule, with the trend toward a finer pattern rule being accelerated. A wavelength change-over from KrF to shorter wavelength ArF laser (193 nm) is expected to enable miniaturization of the design rule to 0.13 μm or less. Since conventionally used novolac resins and polyvinylphenol resins have very strong absorption in proximity to 193 nm, they are difficult to use as the base resin for resists. To ensure transparency and dry etching resistance, some engineers investigated acrylic and cycloolefin resins as disclosed in JP-A 9-73173, JP-A 10-10739, JP-A 9-230595 and WO 97/33198.
Among others, a focus is drawn on (meth)acrylic resin base resists featuring a high resolution. One of the (meth)acrylic resins proposed thus far is a combination of (meth)acrylic units having methyladamantane ester as acid labile group units with (meth)acrylic units having lactone ring ester as adhesive group units as disclosed in JP-A. 9-90637. Acid labile groups of exo form are described in U.S. Pat. No. 6,448,420 (JP-A 2000-327633). These groups have so high an acid elimination ability and require a low level of activation energy for acid elimination, affording a high resolution and low dependence on post-exposure bake (PEB). Norbornane lactone is also proposed as an adhesive group having enhanced etching resistance as disclosed in JP-A 2000-26446 and JP-A 2000-159758. These studies have achieved significant improvements in the resolution of ArF resists.
The outstanding problem associated with the ArF lithography for forming a fine feature pattern is to meet both a high resolution and a minimized size difference between isolated and grouped patterns (known as I/G bias or proximity bias). So far as either one of high resolution and improved I/G bias is concerned, prior art techniques can achieve the goal to some extent. However, it is very difficult to meet both the requirements at a high level.
In general, resins for ArF resists have a structure in which carboxyl groups serving as the alkali soluble group are protected with acid labile groups, and perform such that the acid labile group is deprotected under the action of an acid to regenerate carboxyl groups whereby the resins become soluble in alkaline developers. It is noted that deprotection under the action of an acid is referred to as acid decomposition or "acidolysis." A choice of an acid labile group having higher reactivity may be advantageous with respect to resolution, but enhance acid diffusion during acidolysis reaction, tending to degrade I/G bias. It is thus difficult to meet both resolution and I/G bias at a high level.

Polymerizable ester compounds, polymers, resist compositions and patterning process


The present invention is to provide a document processing device with picture-taking, video and audio recording, scanning and projecting functions, which mainly is including a set of base composed of a left and a right base bodies, a vertical rack bar able to be insert-put on the left and right base bodies, a horizontal rack bar pivot-connected on top of the vertical rack bar, a main machine body pivot-set in the vertical rack bar elements. The said main machine body has an optical lens and is set with a microphone and a light compensator. The device of present invention can be provided for putting the ordinary document data on the base. The data on the documents can be transformed into editable files by utilizing the optical lens inside the main machine body to take the pictures and through the recognizing software. Furthermore, it can record the audio or video in accordance with selected action processes through the main machine body. Simultaneously, the main machine body can further provide for connecting externally with the computers to proceed the image projecting.

Ordinarily, a known method to duplicate the document data generally is to utilize a copy machine or traditional scanner to process. And, these machines have their own different processing performance. For example, the copy machine can directly reproduce the required copies of document data in an extremely fast speed. For reproducing the documents, the efficiency of these machines is extremely high. But their disadvantages are that the volume and weight of the machines and tools are larger and cannot be hand-carried. As for the scanner, it needs to cooperate with a computer then it can proceed the duplicating of paper document data. And, all the aforementioned machines and tools are not equipped with other functions; they thus have no particularity or competitiveness while usage.

Document processing device with picture-taking, video and audio recording, scanning and projecting functions


The present invention provides an advanced spray control system for controlling a sprayer, which comprises a controller, a plurality of sensors and feedback means, and an output means for controlling the application system of the sprayer. The controller receives inputs from the operator through a user interface, and/or various feedback signals from the sensors of the system (e.g., a flow meter, or a pressure transducer). After processing these inputs, the controller sends signals to other components of the sprayer, such as, the pump, the storage means, the boom sections, and/or the nozzles, to maintain or change their operating conditions. Also provided are a method of controlling a sprayer using the spray control system and a sprayer comprising the spray control system of the present invention.

1. Field of the Invention
The present invention relates generally to novel spray control methods and systems for controlling a sprayer, particularly, an agricultural sprayer.
2. Description of Related Art
Sprayers are widely used in agriculture and horticulture for applying chemicals (e.g., insecticides and fungicides) or fertilizers to crops, to protect the crops from diseases, insects, and to facilitate the growth and harvest of the crops.
Most agriculture/horticulture sprayers are designed to be mounted on or towed by a vehicle on the ground, or carried by airplanes or helicopters. These sprayers typically include one or more storage or supply vessels, a left and a right boom or other manifold systems that carry a plurality of geometrically arranged spaced nozzles along its length, a pump for pressurizing and distributing the fluid through pipes or hoses to spray nozzles, and means to control the pump, boom, and spray nozzles.
Currently, two basic categories of feedback controls are used for controlling the function of sprayers: (i) flow volume-based closed loop control system, and (ii) pressure-based closed loop control system. Flow volume-based feedback system measures the flow volume of the substance exiting the machine and feeds this signal back to a controller to control the performance of the machine. Pressure-based feedback system monitors the system pressure, calculates the flow volume using the pressure data, and feeds the information back to a controller to control the performance of the sprayer.
Each of the control systems has its strengths and weaknesses. However, the sprayers and application controllers known in the art only allow one of these control methods to be used for controlling the machines, with the exception of a small number of sprayers and application controllers that allow a second feedback system for monitoring purposes only.
In order to improve the performance of a sprayer, it is therefore desirable to provide a spray control system for controlling sprayers that allows both manual (the operator of the sprayer) or automatic (the controller) control of the spray system to select a feedback control system, or to switch back and forth between the two above-mentioned feedback control systems, based on the needs of the operation or operation conditions.

Adaptive feedback sources for application controllers


A tree pruner consists of a fixed tool and a movable tool fastened pivotally with the fixed tool which is fastened at the lower end thereof with the top end of a support rod. The support rod is provided at the bottom end thereof with two handles for controlling the operation of the fixed tool and the movable tool. The movable tool has an action portion and a blade portion. The action portion is provided with a slide slot having a plurality of arcuate grooves. The fixed tool is fastened pivotally with a rocking arm which is provided at the top end thereof with two support arms. One of the two support arms is provided with a tensile spring which is connected with the fixed tool. Other one of the two support arms is provided with a pull cord which is connected with the handles. The rocking arm is fastened pivotally at the midsegment thereof with one end of a connection rod. Other end of the connection rod is movably disposed in the slide slot of the action portion of the movable tool. The pull cord is activated by the two handles such that the rocking arm and the connection rod are actuated so as to cause the movable tool to turn to sever the twig of a tree.

As shown in FIG. 1, a tree pruner 10 of the prior art has an elongated expandable rod 1 which is provided at the top end thereof with a scissors 2 connected with a transmission member 3. The scissors 2 is controlled by a pair of handles 4. The scissors 2 is formed of a fixed blade 201 and a movable blade 202. Such a prior art tree pruner 10 as described above is defective in design in that it can not sever effectively a rough twig in light of the handles 4 which are incapable of providing the scissors 2 with adequate force of application, and that it can sever the rough twig only after several attempts.

No. 21, Wan Feng Lane, Wan Feng Village, Fu Hsing Hsian


Compositions and methods for production of color images which are developable with improved marking sensitivity and image contrast are disclosed and described. Specifically, a color forming composition can comprise a polymeric activator phase including a polymer matrix and an activator dissolved therein, a color former phase including a color former, and a radiation absorber in thermal contact with the color former phase. Particularly, the color former phase can be finely dispersed within the polymeric activator phase at an average particle size of less than 2 μm.

Compositions which produce a color change upon exposure to energy in the form of light or heat are of great interest in producing images on a variety of substrates. Optical disks represent a significant percentage of the market for data storage of software as well as of photographic, video, and/or audio data. Typically, optical disks have data patterns embedded thereon that can be read from and/or written to one side of the disk, and a graphic display or label printed on the other side of the disk.
In order to identify the contents of the optical disk, printed patterns or graphic display information can be provided on the non-data, or label, side of the disk. The patterns or graphic display can be both decorative and provide pertinent information about the data content of the disk. In the past, commercial labeling has been routinely accomplished using screen-printing methods. While this method can provide a wide variety of label content, it tends to be cost ineffective for production of less than about 400 customized disks because of the fixed costs associated with preparing a stencil or combination of stencils and printing the desired pattern or graphic display.
In recent years, the significant increase in the use of optical disks for data storage by consumers has increased the demand to provide customized labels to reflect the content of the optical disk. Most consumer available methods of labeling are limited to either handwritten descriptions which lack professional appearance, quality and variety, or preprinted labels which may be affixed to the disk, but which can also adversely affect the disk performance upon spinning at high speeds.
Recently, color forming compositions have been developed which can be developed using energy sources such as lasers in order to form an image. However, many of these color forming compositions have development sensitivities that result in slower development time and/or less than acceptable contrast. Thus, the need still exists for improvement in color forming compositions with improved marking sensitivity and image contrast.

This patent is subject to a terminal disclaimer.

Color forming compositions with improved marking sensitivity and image contrast and associated methods

Hewlett-Packard Development Company, L.P.


A droplet jetting apparatus having a droplet jetting head including a nozzle opening formed in a nozzle formation surface, from which droplets of a predetermined liquid are jetted, and a capping device for capping the nozzle opening of the head. A moisture retentive liquid supply device connected to the capping device is provided for supplying a moisture retentive liquid with respect to the predetermined liquid to a space formed by the nozzle formation surface and the capping portion. The weight and the size of the head and its periphery, which is a movable body, are not specifically increased, and accordingly, increase in the cost for motors for driving the droplet jetting head is prevented, thereby effectively avoiding clogging in the nozzle opening of the droplet jetting head. In addition, it is unnecessary to move the droplet jetting head when the moisture retentive liquid is supplied.

1. Field of the Invention
The present invention relates to a droplet jetting apparatus having a droplet jetting head in which a specific liquid is jetted as droplets from nozzle openings and a capping device for capping a nozzle opening of the droplet jetting head so as to prevent drying of the liquid or clogging of the nozzle opening, and also relates to a method of operating the droplet jetting apparatus and to a device manufacturing method.
Priority is claimed on Japanese Patent Application No. 2004-023872, filed Jan. 30, 2004, the content of which is incorporated herein by reference.
2. Description of Related Art
Generally, a droplet jetting head includes a pressure generating chamber for containing a specific liquid, a piezo actuator for compressing the pressure generating chamber, and a nozzle opening communicated with the pressure generating chamber. The liquid in the pressure generating chamber is compressed by the piezo actuator, thereby jetting a small amount of liquid from the nozzle opening as a droplet. In the droplet jetting head having the above structure, if liquid in the neighborhood of the nozzle opening is evaporated or if air bubbles remain inside the droplet-jetting head, a problem occurs in droplet jetting. Therefore, the above kind of droplet jetting head requires a capping device for capping or sealing the nozzle opening so as to prevent drying of the liquid or clogging of the nozzle opening.
The capping device includes a capping portion for capping the nozzle opening and an attraction pump for supplying negative pressure to the inside of the capping portion. The capping device not only caps the nozzle opening of the droplet jetting head by using the capping portion but also applies negative pressure to the capping portion by using the attraction pump so as to forcedly discharge the liquid from the nozzle opening, thereby discharging the liquid having increased viscosity in the neighborhood of the nozzle opening or air bubbles remaining in the pressure generating chamber.
Detailed descriptions about the conventional droplet jetting apparatus having the above-explained droplet jetting head and the capping device are found, for example, in Japanese Unexamined Patent Application, First Publication No. 2001-018408.
In the droplet jetting apparatus disclosed in the above document, an absorbent material is provided in the capping portion. When no printing is performed or the power source is off, a specific quantity of moisture retentive liquid is supplied in advance from a moisture retentive liquid tank to the absorbent material before capping of the nozzle opening, so as to reduce evaporation of the liquid from the nozzle opening after the capping, thereby maintaining the moist atmosphere in the capping portion.
However, droplets of the moisture retentive liquid drop from the moisture retentive liquid tank which is mounted on a carriage; thus, the size and the weight of the carriage is increased and increase in the cost for a carriage motor is unavoidable.
In addition, even when the nozzle opening of the droplet jetting head is capped using the capping device, if the capped state continues for a long period of time, increase in the viscosity of the liquid may occur due to decrease in moisture retention which is caused by evaporation of the liquid in a passage for the liquid or from a nozzle opening, or by drying in the capping device, so that the nozzle opening may be clogged. Accordingly, there is a demand to supply moisture retentive liquid to the capping portion at regular intervals after capping the nozzle opening, while maintaining the capped state of the nozzle opening.
As another method for clearing the clogging of the nozzle opening, other than the method of using a capping device, (i) a cleaning method is known, in which negative pressure is applied to a nozzle formation surface (i.e., a surface in which nozzle openings are formed) of the droplet jetting head so as to attract the liquid from the nozzle openings, and the nozzle forming plane is cleaned using a wiper after the attraction of the liquid, or (ii) a flushing method is known, in which the pressure applied to the pressure generating chamber by using the piezoelectric element is increased so as to forcedly jet droplets greater than a normal quantity of jetted droplets. However, in the above methods, the liquid is uselessly consumed and the life of the droplet jetting head or the wiper is reduced.

Droplet jetting apparatus, method of operating droplet jetting apparatus, and device manufacturing method