The method for dicing a wafer including the steps of: reducing a thickness of a wafer to at least 0.1mm or less; forming a protection sheet tightly on one side of the wafer, the protection sheet having a Vickers hardness of 2 or more; and dicing the wafer by a grindstone, the wafer having the protection sheet thereon.

1. Field of the Invention
The present invention relates to a method for dicing a wafer, particularly to a method for dicing and separating a thin wafer in the process of manufacturing, for example, a non-contact type IC card.
2. Description of the Related Art
Silicon wafers of the thin film type have been used in a variety of fields, such as in the field of manufacturing a non-contact type IC card. Non-contact type IC cards have been used in a lot of fields, such as the application to ticket gates of railroads, and are expected to be applied in a lot of fields in the future. A non-contact type IC card has an antenna, a semiconductor chip (IC chip), and a sheet material to cover the antenna and the IC chip. Silicon wafers of the thin film type are also used for the manufacturing of cellular phones and various types of sensors.
The reasons for using thin silicon wafers in these products are as follows. The thickness of a wafer is related to the thickness of IC cards which are to be produced when a wafer is used for IC cards. Moreover, thin silicon wafers are advantageous because of their flexibility which allows them to be bent without causing any damage during use. ICs, when applied to cellular phones, need compact and three-dimensional mounting within a small space by methods such as piggyback stacking. For these reasons, IC chips are required to be processed as thin as possible. ICs, when applied to, for example, sensors, are required to be processed thin to ensure mounting of the chips, as well as to ensure a reduction in chip size.
An IC chip consists of a chip portion, which has a base plate made of stacked films of silicon etc. to form circuits thereon, and a reinforcing plate, which is normally made of stainless steel, to support the chip portion. The reinforcing plate has the function of protecting the chip portion against excessive deformation and of a heat sink which absorbs heat that is generated in the chip portion.
Various methods for manufacturing an IC chip have been proposed. According to a known art, deep grooves are formed in a wafer prior to dicing the wafer. In this method, first, deep grooves are formed along the chip to a depth that is larger than the thickness of the finished wafer. Next, the wafer is attached to a base plate via an adhesive tape or wax that is applied on the base. The wafer is then ground to a predetermined thickness from the back side of the wafer to separate the wafer into chips. However, there are some drawbacks in this method because of the internal stress and internal distortion which are induced within the wafer due to the machining on the side which is ground. First, the chips are more apt to have cracks due to external forces. Secondly, as the chips become thinner, their characteristics, as an element, tend to be more affected. In particular, the characteristics may be significantly deteriorated when the chip is used for, for example, as a magnetic sensor. Furthermore, as chips become smaller, chips tend to peel from the base plate during grinding, or tend to experience chipping because of the vibration and displacement during grinding. The term 'chipping' means a crack in a wafer along a dicing line.
Therefore, another process may be used in which a wafer is diced into chips after the wafer is made thinner. In this method, a wafer having a plurality of chip portions thereon is made thinner from the back side of a wafer, and then the thin wafer is diced into individual chip portions. Finally, the separated chip portions are attached to reinforcing plates in order to manufacture IC chips.
Specifically, this method is carried out in accordance with the following steps. First, a wafer is attached to a base plate, and then ground without being separated into chips at this step.
The surface may be etched after grinding in order to remove the distortion that is generated on the surface through the machining process. Etching may be performed through wet etching using fluoro-acid etc., or through milling in a vacuum, or through reactive etching in a vacuum such as RIE. However, in this method, it is not desirable to form grooves first for the following reasons. In a wet process, as well as in the reactive etching process, the etching solution may flow out to the opposite side of the wafer, causing damage on the surface of the elements. In a physical etching process such as milling, the elements are more apt to be damaged by the heat that is generated during milling. Removing the stress by means of etching etc. using such a process after the wafer is made thinner facilitates obtaining flat chips after the chips are removed from the base plate. In this way, chips are uniformly attached onto base plates, such as heat sinks, and become more resistant to cracks which are generated by external forces. When the elements are used, for example, as sensors, their characteristics, as an element, are less affected.
Next, a plastic sheet made of polyester or the like is placed on a dicing base. The plastic sheet is then fixed on the dicing base with the help of negative pressure on the back side of the plastic sheet. Next, resin, such as ultraviolet curing resin or thermosetting resin, is applied on the plastic sheet, as shown in the specifications etc. of Japanese Patent Laid-open Publication No. 2002-270676 and 92778/98. Such a stacked structure formed in this manner consisting of the plastic sheet and the resin is called a processing tape.
The reason for applying resin on a wafer is as follows. A wafer, which is diced along the boundaries between the chip portions, has an exposed portion of the base plate made of silicon etc. along the boundaries, and terminals for inspection on the back side of the chip portions, and the brittleness of the terminals and the base plate facilitates the occurrence of chipping. Although the chip portion is covered with a protective film made of materials such as polyimide, foreign substances, such as gas or water, will invade the chip portion to cause corrosion, when chipping at the boundary reaches the protective film. Moreover, the concentration of chipping may lead to stress concentration, which causes cracks which grow from the location of the chipping during temperature cycles and which result, in the worst case, in the fracture of the element. For this reason, it is important to prevent the chipping while dicing a wafer. The application of resin, such as ultraviolet curing resin or thermosetting resin, reduces resistance against dicing, which may cause chipping, and also stabilizes (prevents the deflection of) the wafer and the grindstone during dicing. In addition, removal of resin, which becomes unnecessary after dicing, can be facilitated.
Next, the processing tape is held by a fixing device, called a dicer ring, and stretch (tension) is applied to the processing tape in order to prevent air from entering the space between the dicing base and the processing tape, and thereby to make the processing tape flat. Next, a wafer is attached to the processing tape on the side of the resin. These processes can be automatically performed by special equipment called a mounter.
Next, the wafer having the processing sheet thereon is diced by a grindstone which has abrasive grains made of, for example, artificial diamond. The chipping depends largely on the particle size (The particle size is the index of the particle diameter of grains in a grindstone. A grain size number means the density of grains per one square inch. The grain size number is in proportion to the number of the grains, and is in inverse proportion to the diameter of the particle.) A grindstone with large particle diameters tends to get stuck in a wafer and to cause chipping because of the large resistance against dicing. Thus, in general, a grindstone having particles with small diameters, or particles with large particle number, is used to dice a thin wafer, which is apt to have chipping. In the field of semiconductors, grindstones with a grain size number between 2000s and 4000s are used.
The processing sheet is peeled after dicing the wafer. In order to peel the processing sheet, according to a disclosed method, a needle is stuck to the back surface of the processing sheet in order to partially separate the chip portion from the processing sheet, and then the chip portion is picked up by vacuum tweezers etc. See, for example, the specification etc. of Japanese Patent Laid-open Publication No. 151265/94.
Thus, the method of dicing a wafer into chips after making the wafer thinner, which enables improvement in the reliability and uniformity in the characteristics of the separated chips, has been used more frequently in line with the trend toward reduced chip size and increased chip density.
Recently, a dicing technology which uses laser also has been widely studied.
However, there are the following drawbacks in prior art. Specifically, wafers have become increasingly thinner in recent years as mentioned above. However, as a wafer becomes thinner, a wafer is apt to move up and down during dicing, and the grindstone experiences unstable movement, resulting in the increased possibility of fine cracks, i.e., chipping. The result is the same even if a protection tape mentioned above is used. Furthermore, a wafer the surface of which is etched after being made thinner, becomes significantly less resistant against peeling during dicing, because the capacity to hold the wafer during dicing, which is due to the thickness of the base plate, is weakened. If a wafer is attached to a base plate with a tougher adhesive in order to improve resistance against peeling, removal of chips becomes more difficult, resulting in a significant reduction in yield in the separating process after dicing, as well as resulting in damage to the chips.
Grindstones with larger grain size numbers may be used in order to reduce the resistance against dicing. However, the method is economically disadvantageous, because grindstones become more expensive as the grain size number is increased. Alternatively, resistance against dicing can be suppressed by reducing dicing speed, i.e., by reducing dicing speed to an extremely low speed at first (for example, about 5 mm/sec), then by gradually increasing the dicing speed while checking the dicing condition to confirm whether there are problems or not. However, this method worsens working efficiency because of the need to check the dicing condition and because of the low average dicing speed.
In addition, the method for dicing a wafer that uses a laser is disadvantageous in that the heat generated during irradiation may damage a wafer, especially a thin wafer.
Thus, there remain major problems of how to prevent chipping when a thin wafer is diced. It is pointed out that the problem of chipping becomes significant especially for a wafer that is less than 0.1 mm in thickness, as mentioned, for example, in the specification etc. of Japanese Patent Laid-open Publication No. 2002-270676.
Moreover, because tension in the processing tape and in the resin film as well, that is given after the application of resin, is released such that the resin film deforms to shrink locally as soon as the resin film is diced, the dicing plane of a wafer moves during dicing, causing, in the worst case, cracks on the wafer or on elements formed on the wafer.

Method for cutting a wafer using a protection sheet


A vibration-welded structure includes a welding rib having a weld surface, which is provided on each of two parts to be welded with each other. At least one guide portion is provided on one of the two parts, and the at least one guide portion is capable of guiding a movement of the welding rib of the other of the two parts in a vibration direction.

Various types of resin or plastic parts have been used in a vehicle such as an automobile. As such a resin part, one is known which is joined by performing vibration welding (see, for example, Patent Document 1).
In the vibration welding, for example, as shown in FIG. 3, a first part 1 is provided with a welding rib 3. A welded surface 2 of the welding rib 3 is attached to a general surface 5 of a second part 4 and vibrated (in a vibration direction 6) so that a vicinity of the welded surface 2 is frictionally melted to weld the two parts (welded portion 7).    [Patent Document 1] Japanese Patent Application Publication No. 2006-218822
However, in a vibration-welded structure obtained by the above vibration welding, as shown in FIG. 4, sufficiently large friction can not be obtained if there is an angle between the welded surface 2 and the vibration direction 6. Accordingly, there are problems in that the welding strength decreases so that failure in welding easily occurs. In particular, it becomes impossible to weld the two parts in a case where the angle between the welded surface 2 and the vibration direction 6 becomes large.


In accordance with one embodiment, an image forming apparatus comprises a fixing device and a control section. The fixing device is provided with a fixing roller for conveying a sheet. The control section changes the rotation speed of the fixing roller based on a shrinkage rate of the sheet before and after the passing of the sheet through the fixing device. The control section changes, according to the shrinkage rate, the rotation speed of the fixing roller in the second and the following fixing processing carried out by the fixing device in a case in which the same sheet passes through the fixing device more than twice.

There is an image forming apparatus which conveys a sheet-like medium (hereinafter collectively referred to as "sheet") such as paper and meanwhile forms an image on the sheet. The image forming apparatus is provided with a fixing device. The fixing device applies heat and pressure to the sheet to which the image is transferred to fix the image on the sheet. Thus, there is a possibility that the moisture contained in the sheet passing through the fixing device is evaporated, and as a result, the sheet is shrunk. The shrinkage degree of the sheet varies according to the category of the sheet. The shrunk sheet returns to the original size after a few minutes.
However, in a case of printing images on both sides of the sheet, there is a case in which the image is printed on the second surface before the sheet returns to the original size. As a result, when the sheet returns to the original size, the image printed on the second surface is stretched compared with the image printed on the first surface.

Image forming apparatus and image forming method which adjust image magnification based on sheet shrinkage


A method for communicating to a plurality of peripheral devices in a computer system, the computer system comprising a first expansion bus, a bus bridge for coupling to the first expansion bus and for interfacing to a second bus, a second bus coupled to the bus bridge, and a plurality of peripheral devices connected to the second bus. The method includes activating a source port in the bus bridge to configure the source port in the bus bridge for a transfer. Next, the bus bridge receives and stores an address from the first expansion bus in a source port of the bus bridge. The address identifies a destination port on one of the plurality of peripheral devices. The bus bridge then receives and stores data from the first expansion bus in a buffer. The data is to be sent to the destination port. The bus bridge then transmits one or more address/data pairs to the destination port of the peripheral device. The address/data pairs each includes the address received from the first expansion bus and the data received from the first expansion bus. The transmitting is performed automatically in response to receiving the data from the first expansion bus when the source port is activated.

1. Field of the Invention
The present invention relates to bus architectures, and more particularly to a bus bridge architecture for interconnecting a plurality of devices through bridge logic to a PCI bus.
2. Description of the Related Art
Personal computers are increasingly being used for multimedia and communication applications. Examples of multimedia applications include applications with audio and/or video presentation components. Examples of communication applications include e-mail clients, web browsing, and intranet access, among others.
A multimedia application which includes audio typically interfaces to an audio source and/or destination device. Audio sources which may need to be supported include television, radio, microphones, and compact disks, as well as telephony and modem applications. however, multimedia computers must do more than merely function as an audio switching unit from source to speakers and headphones. Multimedia computers must also provide the user the capability to manipulate the audio signals in an interactive fashion. Thus, it is desirable to provide a personal computer which can support music synthesizers, audio mixers, sound effects synthesizers, and the like, in addition to any associated stereo and mono codes. Such functionality may be provided on a centralized audio chipset, which may receive signals from all audio sources.
It is frequently desirable to provide multiple audio and/or communication devices, and particularly telephony and modem devices, on an expansion card. However, most modem multimedia computers employ the Peripheral Component Interconnect (PCI) bus architecture. While the PCI bus accommodates expansion slots for add-in cards, each card is permitted to provide only one load on the bus. Accordingly, if multiple devices, such as multiple modems, are desired to be supported on a given expansion board, the devices must connect to a bus on-board the bridge device. A bridge device is required to interface between the devices connected to the on-board bus and the computer's expansion bus.
A variety of options is available for an on-board bus connecting to a computer expansion bus. A standard expansion bus, such as an Industry Standard Architecture (ISA), Extended Industry Standard Architecture (EISA) or Microchannel Architecture (MCA) may be employed. Bus bridges connecting each of these buses to a PCI bus are known. However, while such bus interconnections are an option, each of the above mentioned buses is an asynchronous bus requiring a bus master and relatively complex arbitration mechanism to support multiple devices. In addition, each of these bus standards is relatively slow. In time-critical isochronous functions, such as multimedia audio, this can introduce undesirable delays, both when the devices must communicate with one another and when they must communicate across the bus bridge on the PCI bus to the host computer. However, there is a large base of, for example, ISA bus compatible multimedia devices which could frustrate any move to a new standard. In addition, devices according to each of the above standards require a large number of pins to interface with the PCI bus.
Accordingly, there is a need for a more efficient bus bridge interconnect architecture for multimedia-related devices for interconnection and for interfacing to a standard bus, which also maintains support for an existing body of devices compatible with a previous standard and minimizes the number of pins required for connection. More particularly, there is a need for a bus mechanism for functionally coupling a plurality of multimedia devices to a PCI bus, while providing support for devices employing the ISA standard.

Inter-chip bus structure for moving multiple isochronous data streams between integrated circuits


Compositions useful in the delivery of active agents are provided. These delivery compositions include (a) an active agent; and either (b)(1) a carrier of (i) at least one amino acid and (ii) at least one diketopiperazine or (b)(2) at least one mono-N-substituted, di-N-substituted, or unsubstituted diketopiperazine. Methods for preparing these compositions and administering these compositions are also provided.

Conventional means for delivering active agents are often severely limited by biological, chemical, and physical barriers. Typically, these barriers are imposed by the environment through which delivery occurs, the environment of the target for delivery, or the target itself.
Biologically active agents are particularly vulnerable to such barriers. For example in the delivery to animals of pharmacological and therapeutic agents, barriers are imposed by the body. Examples of physical barriers are the skin and various organ membranes that must be traversed before reaching a target. Chemical barriers include, but are not limited to, pH variations, lipid bi-layers, and degrading enzymes.
These barriers are of particular significance in the design of oral delivery systems. Oral delivery of many biologically active agents would be the route of choice for administration to animals if not for biological, chemical, and physical, barriers such as varying pH in the gastrointestinal (GI) tract, powerful digestive enzymes, and active agent impermeable gastrointestinal membranes. Among the numerous agents which are not typically amenable to oral administration are biologically active peptides, such as calcitonin and insulin; polysaccharides, and in particular mucopolysaccharides including, but not limited to, heparin; heparinoids; antibiotics; and other organic substances. These agents are rapidly rendered ineffective or are destroyed in the gastrointestinal tract by acid hydrolysis, enzymes, or the like.
Earlier methods for orally administering vulnerable pharmacological agents have relied on the co-administration of adjuvants (e.g., resorcinols and non-ionic surfactants such as polyoxyethylene oleyl ether and n-hexadecylpolyethylene ether) to increase artificially the permeability of the intestinal walls, as well as the co-administration of enzymatic inhibitors (e.g., pancreatic trypsin inhibitors, diisopropylfluorophosphate (DFF) and trasylol) to inhibit enzymatic degradation.
Liposomes have also been described as drug delivery systems for insulin and heparin. See, for example, U.S. Pat. No. 4,239,754; Patel et al. (1976), FEBS Letters, Vol. 62, pg. 60; and Hashimoto etal. (1979), Endocrinology Japan, Vol. 26, pg. 337.
However, broad spectrum use of such drug delivery systems is precluded because: (1) the systems require toxic amounts of adjuvants or inhibitors; (2) suitable low molecular weight cargos, i.e. active agents, are not available; (3) the systems exhibit poor stability and inadequate shelf life; (4) the systems are difficult to manufacture; (5) the systems fail to protect the active agent (cargo); (6) the systems adversely alter the active agent; or (7) the systems fail to allow or promote absorption of the active agent.
More recently, microspheres of artificial polymers of mixed amino acids (proteinoids) have been used to deliver pharmaceuticals. For example, U.S. Pat. No. 4,925,673 describes drug-containing proteinoid microsphere carriers as well as methods for their preparation and use. These proteinoid microspheres are useful for the delivery of a number of active agents.
Steiner et al., World Patent Publication No. W093/18754, disclose a drug delivery system in which a drug cargo is encapsulated within a microparticle formed of specific di-substituted diketopiperazine sub-units. The diketopiperazines are only substituted with side chain substituents at two of the carbons in the ring, and at least one of those substituents must include an ionizable group. Neither the diketopiperazines nor the sub-units are combined with any other amino acid.
There is still a need in the art for simple, inexpensive delivery systems which are easily prepared and which can delivery a broad range of active agents.


A heterocyclic urea compound, and specifically discloses an indoleamine-2,3-dioxygenase inhibitor of a heterocyclic urea compound, which solves the problems of weak curative effect and larger toxic and side effects of existing immunological therapy drugs. The invention further provides a preparation method for an indoleamine-2,3-dioxygenase inhibitor of a heterocyclic urea compound, and an application of the indoleamine-2,3-dioxygenase inhibitor of a heterocyclic urea compound or a pharmaceutically acceptable salt thereof in preparing drugs for treating or preventing tumors.

Tryptophan is one of the essential amino acids in a body of a mammal, and plays an important role in a biosynthesis process of some important proteins and nicotinic acids as well as some neurotransmitters (e.g., 5-hydroxytryptamine, i.e., serotonin) in the body, thus maintaining cell activation and proliferation. The tryptophan needs to be taken in large quantities from food, and the deficiency of the tryptophan may lead to the dysfunction of some important cells.
Indoleamine-2,3-dioxygenase (IDO) is a monomeric enzyme containing heme, which was firstly found in a cell by Hayaishi group in 1967, and a cDNA encoding protein is composed of 403 amino acids with a molecular weight of 45 kDa, and is widely expressed in various mammalian tissues (Hayaishi O. et al Science, 1969, 164, 389-396).
The IDO is responsible for cleaning up the tryptophan in a human body, and is the first enzyme in a metabolic pathway of the invivo tryptophan and is a rate-limiting enzyme. The IDO can catalyze the tryptophan to be converted into N-formylkynurenine through oxidation reaction, and when the IDO is overexpressed, a microenvironment of deletion of the invivo tryptophan can be caused. The IDO is closely related to the pathogenesis of many diseases, and it has been proved to be a target of major diseases such as cancer, Alzheimer's disease, depression, and cataract (Swanson et al. Am. J. Respir. Cell Mol.Biol. 2003 30, 311) (Guillemin G. J. et al Neuropathol. and Appl. Neurobiol. 2005, 31, 395-404). Finding a high-efficiency inhibitor based on the IDO target has become a research hotspot in drug development in recent years.
The research has shown that the IDO can inhibit a local T cell immune response in a tumor microenvironment through the following ways: tryptophan depletion, toxic metabolism and induced regulatory T cell proliferation. In many cases, the IDO is overexpressed in tumors, thus consuming local tryptophan and generating a large number of metabolites such as kynurenine. In fact, under a culture condition of lacking the tryptophan or the kynurenine, proliferation inhibition, activity reduction and even apoptosis can occur to a T cell. However, there is a regulatory point very sensitive to a tryptophan level in the T cell, tryptophan consumption caused by the effect of the IDO can cause the T cell to stagnate in a GI phase, thus inhibiting T cell proliferation and T cell immune response. However, once the T cell proliferation is stopped, the T cell cannot be stimulated again, which is an immune mechanism of the IDO in the body (Mellor A. et al Biochem. Biophys. Res. Commun. 2005, 338, 20-24) (LeRond S. et al J Exp. Med 2002, 196, 447-457). Inhibition of IDO activity can effectively prevent the degradation of the tryptophan around a tumor cell and promote the T cell proliferation, thus enhancing the body's ability to attack the tumor cell. The IDO inhibitor can also be combined with chemotherapy drugs to reduce a drug resistance of the tumor cell, thus enhancing an anti-tumor activity of conventional cytotoxic therapy. Meanwhile, taking IDO preparation can also improve a curative effect of a therapeutic vaccine for a cancer patient. The research and development of the IDO inhibitor has become a hot field of tumor immunotherapy.
The IDO inhibitor has a broad application prospect as the drug, but no suitable IDO inhibitor has been put on the market as the drug so far, and it is of great theoretical significance and application value to find a new and efficient IDO inhibitor.

Heterocyclic urea compound, and drug composition and application thereof


A hydraulic anti-lock brake system is disclosed in which the pressure in the wheel brakes can be regulated by means of an inlet valve and an outlet valve in response to the wheel rotational pattern. The wheel brake is supplied with pressure fluid out of the pumps through the inlet valve, and pressurized fluid is taken therefrom through the outlet valve. A differential pressure limiter (18) in front of the inlet valve (15) limits the difference in pressure allowed to build up across the inlet valve by closing a valve until a sufficient pressure build up occurs on the wheel brake. This considerably decreases the noise developed during valve operation. A pressure relief valve (30) insures that an evenly high pressure build-up takes place when the inlet valve (15) is closed by opening when a predetermined pressure difference develops across the inlet valve to allow a higher wheel brake pressure to equalize with the pressure upstream from the inlet valve.

The present invention relates to an anti-lock hydraulic brake system with at least one wheel brake and an auxiliary pressure source, wherein an inlet valve is inserted into the line between the auxiliary pressure source and the wheel brake and the wheel brake is connected to a return line via an outlet valve, wherein a differential pressure limiter is disposed within the line between the auxiliary pressure source and the inlet valve, the closure member of which is acted upon by both the force of a valve spring and the pressure in the wheel brake in a manner opening the line.
A brake system of this type is known from German published patent application 38 42 699.1. The latter describes a dual-circuit brake system with a tandem master cylinder and a pump for each brake circuit. The wheel brake cylinders each communicate via a respective inlet valve with the pressure line leading to the pump and, also with the brake line leading to the master brake cylinder. Each brake cylinder communicates via a respective outlet valve with the return line to the supply reservoir. Each inlet valve is normally open, while the outlet valves are normally closed.
The rotational behavior of the wheels is constantly monitored during a braking operation. In the event of an imminent locked condition of any one of the wheels, the drive of the pump is activated, and the inlet and outlet valves of the imminently locking wheel controlled such as to develop an amount of pressure in the wheel brakes which correlates with an optimal slip value of the wheel. To decrease the pressure, the outlet valve is opened and the inlet valve closed. Both valves are closed to retain the pressure, whilst for the pressure increase the inlet valve is open and the outlet valve is closed.
The inlet and the outlet valves are electromagnetically operated valves having a closure member which is seated on a valve seat.
Starting from a brake fluid pressure which is in excess of the pressure which corresponds to the force of the valve spring, a differential pressure limiter between the auxiliary pressure source and the inlet valve causes a defined constant pressure gradient to prevail on the inlet valve which is determined by the valve spring. This pressure gradient can be adjusted to 25 bar for example, and hence is considerably less than the pressure gradient which usually occurs when an emergency stop anti-lock controlled braking operation is performed by the brake system.
However, it has been discovered that dynamic actions in the return line and in the differential pressure limiter can cause the pressure in front of the inlet valve to build up to a level higher than what is desired.
Hence the present invention has for its object to develop measures ensuring that the pressure gradient at the inlet valve remains constant under all circumstances.


Transformed cell lines containing a reporter gene operatively linked to a genetic control element that is responsive to growth factor-stimulated cell proliferation and/or oncogene-mediated neoplastic transformation are provided. Also provided are methods for using such transformed cell lines to screen for growth factor antagonists and/or antineoplastic agents.

Most screening systems currently used to identify potential antineoplastic drugs evaluate the ability of compounds to kill rapidly-growing cells in culture. Drugs identified in such systems are thus generally not specific for tumor cells but are also toxic to rapidly-growing normal cells in the body. Out of more than 400,000 compounds that have been evaluated in such systems, fewer than twenty have shown an acceptably low level of toxicity, and even these compounds show toxic effects in most cancer patients.
More effective cancer chemotherapy will require the identification of new drugs that act to specifically kill cancer cells or to suppress the transformed phenotype, while exhibiting low toxicity to normal cells. To find these new drugs, new screening systems will be required.
Our understanding of the molecular basis of cancer has been revolutionized by the identification of a relatively small set of normal cellular genes called protooncogenes which, when altered, can produce neoplastic change Bishop, Ann. Rev. Biochem. 52:301 (1983); Varmus, Ann. Rev. Genetics 18:553 (1984)!. Alterations in protooncogene expression can occur for a variety of reasons, including mutations, nucleotide substitutions, chromosomal translocations, gene amplifications, and the insertion of mobile genetic elements. As a result of such changes, the expression of protooncogenes may be altered or they may be mutated to encode altered protein products.
The proteins encoded by protooncogenes play an important role in governing many aspects of cell growth and development. Mutant or activated protooncogenes are believed to make specific contributions to the phenotypes of tumor cells and hence are called oncogenes.
One of the remarkable features of cellular protooncogenes is that they have shown extraordinary conservation during evolution. Several of these genes have been identified in organisms as diverse as yeast, mammals, birds, fish and insects. This evolutionary conservation suggests that the proteins encoded by the protooncogenes must have important functions in normal cell growth and development, with each directing a particular event in the complex system of signals that regulates the proliferation and differentiation of cells. Changes in any one or more of these genes can lead to cancer (Bishop, supra; Varmus, supra).
The proteins encoded by protooncogenes fall into several groups. Some are growth factors--polypeptides that signal cells to divide. Others are receptors for growth factors, molecules that are embedded in the cell membranes and respond to growth factors. Another group is known as the group of G proteins, which transmit signals from receptors to other components of the signal-transduction pathway. Others are protein kinases which phosphorylate other proteins. Still others are nuclear proteins that are involved in DNA transcription Weinberg, Science 230:770 (1985)!. A schematic representation of the pathway by which signals generated outside a cell can transmit information to the nucleus to produce cell division is shown in FIG. 1.
More recent research has focused on the part played by negative regulators of cell growth in the development of cancer. These negative regulators are known as tumor suppressor genes (also known as recessive oncogenes or anti-oncogenes). Unlike oncogenes of viral and cellular origin, which appear to act in a dominant manner to confer transformed characteristics, loss of both copies of these recessive oncogenes is required for neoplastic change Stanbridge, Bioessays 3:252 (1985)!.
A protein called the Rb protein which is encoded by one such anti-oncogene, the retinoblastoma anti-oncogene, is presumed to act in the control of the cell cycle. Oncogenes carried by DNA tumor viruses such as SV-40 large T antigen and adenovirus EIA function by complexing with and inactivating the Rb protein Whyte, et al., Nature 334:124 (1988)!.
Although oncogenes have been linked to tumor growth, the signalling pathways controlled by oncogene proteins are not limited to growth control alone. Oncogene-encoded proteins probably regulate other biological activities such as transmission of nerve impulses, phototransduction, chemotaxis, differentiation, etc. Alterations in pathways controlling such activities may play an important role in other diseases such as atherosclerosis and Alzheimer's disease. Hence, specific drugs designed to inhibit the activities regulated by mutant oncogene proteins may prove useful in the treatment not only of cancer, but of many other diseases as well.
When rat embryo fibroblasts undergo neoplastic transformation, microfilaments containing actins and myosins are reorganized from a bundle state into a randomly interwoven meshwork Pollack et al., Proc. Natl. Acad. Sci. USA 72:994 (1975)!. This phenomenon, known as actin cable network diffusion, has been found to be a common characteristic of many such transformed cells. Studies indicate that changes in different cytoskeletal components are not an indirect consequence of transformation but are specific to the oncogenes that cause transformation Franza et al., Cancer Cells 1:137 (1984); Leavit, J., in Human Fibroblast Transformation (Ed., G. Milo), CRC Press Inc., 1989, pp. 1-28!.
Changes in the arrangement of cytoskeletal components have been associated with alterations in cell growth rate, attachment, saturation density and the expression of the differentiated phenotype. Such changes may favor neoplastic growth and play an important role in tumor initiation or progression. Although detailed understanding of the molecular mechanisms involved in these cytoskeletal changes is lacking, it is clear that some genes which are silent in normal cells are turned on in transformed cells, and that certain others that are expressed in normal cells are turned off following transformation.
Studies by Leavitt et al. Nature 316:840 (1985)! and Garrels et al. Cancer Cells 1:137 (1984)! have shown that smooth muscle .alpha.-actin isoform is expressed in both Rat2 and REF52 cells and is repressed following neoplastic transformation of the cells by several RNA and DNA tumor viruses.
Investigations on the human smooth muscle myosin light chain-2 (MLC-2) isoform have shown that the MLC-2 gene also is specifically repressed when fibroblasts undergo neoplastic transformation Kumar et al., Biochemistry 28:4027 (1989); Kumar et al., in Cytoskeletal Proteins in Tumor Diagnosis, 1989, Weber et al., Eds., Cold Spring Harbor Press, p. 91!. Revertants of such transformed cells show normal levels of MLC-2 gene expression.
In view of the diverse roles played by oncogenes in cellular regulation and the relationship of oncogene activity to diseases such as cancer, it would be desirable to identify agents that can specifically alter oncogene-mediated biological processes, thereby reversing or suppressing the disease state. There is thus a need for specific in vitro screening systems for that purpose.
The proliferation and differentiation of mammalian cells are controlled by a family of polypeptide growth factors Holley, Nature 258:487 (1975)!. All polypeptide growth factors act by binding to specific cell surface receptors that, upon activation, transduce a broad range of signals leading to cell growth and differentiation James et al., Ann. Rev. Biochem. 53:259 (1984)!. A number of growth factors and their receptors have been characterized in recent years, including, e.g., epidermal growth factor (EGF), fibroblast growth factors (FGFs), platelet-derived growth factor (PDGF; a dimeric protein consisting of two "A" chains, two "B" chains or one "A" chain and one "B" chain), insulin-like growth factors (IGFs) and Bombesin. Many of the growth factor receptors have an intrinsic tyrosine kinase activity and contain very closely related structural elements.
Each growth factor may have a specificity for certain cells or tissue types. In many cases, however, they can also induce a response in other cell types. For example, EGF, the major target of which is epithelial cells, can also elicit a response from fibroblast cells. Fibroblast growth factor (FGF) is a potent stimulator of vascular endothelium and thus may be important in angiogenesis. At the same time FGF can stimulate other cell types such as fibroblasts and smooth muscle cells. PDGF is a key mitogen for smooth muscle cells and fibroblasts but has no direct effect on vascular endothelium or epithelium.
It has long been known that transformed cells in culture are generally able to grow in much lower concentrations of serum than are nontransformed cells. Serum is the normal source of growth factors for cultured cells. It was later discovered that fibroblasts transformed by certain retroviruses secrete factors which transiently induce normal cells to express a transformed phenotype Todaro et al., in Genes and Proteins in Oncogenesis, 1983, Weinstein and Vogel, Eds. Academic Press., New York, N.Y., pp. 165-181; DeLarco et al., Proc. Natl. Acad. Sci. USA 75:4001 (1978); Todaro et al., Cancer Res. 38:4147 (1978)!.
These factors, known as transforming growth factors (TGFs), consist of two functionally and structurally distinct groups of factors called TGF-.alpha. and TGF-.beta. Sporn et al., Nature 313:745 (1985)!. TGF-.beta. acts as a growth inhibitor for certain cell types, and as a mitogen for other cell types. The discovery of these TGFs led to the suggestion that one of the ways by which cells become transformed is by endogenous production of growth factors for which they have receptors Sporn et al., N. Eng. J. Med. 303:878 (1980)!. This internal production of growth factors is believed to serve as a constant stimulus for continued cell division, releasing the cells from their normal endogenous physiological controls.
The binding of growth factors to cellular receptors stimulates an array of biochemical responses, including changes in ion fluxes, activation of a number of protein kinases and alternation of transcriptional rates of several genes. These events culminate hours later in DNA replication and cell division. Recent studies have led to the delineation of pathways by which signals, generated at the membrane by the binding of a growth factor to its receptor, are transduced to the nucleus Ullrich et al., Cell 61:203 (1990); Williams, Science 24:1564 (1989)!. Increased expression of genes encoding transcription factors is an important element of the signal transduction mechanism which assures long term transcriptional response of cells to growth factors.
Smooth muscle .alpha.-actin isoform is expressed in both vascular smooth muscle and fibroblast cells Vandekerckhove et al., Differentiation 14:123 (1979); Leavitt et al., Nature 316:840 (1985)!. Actively proliferating aortic smooth muscle cells are known to contain relatively low levels of .alpha.-actin protein, whereas post-confluent cells show a nearly three-fold increase Owens et al., J. Cell Biol. 102:343 (1988); Corjay et al., J. Biol. Chem. 264:10501 (1989)!. Addition of PDGF to quiescent aortic smooth muscle cells results in a decrease in the steady state level of .alpha.-actin mRNA (Corjay et al., supra).
Abnormal cell proliferation due to the action of various growth factors is associated with a number of diseases such as neoplasia, atherosclerosis and myelofibrosis. To alleviate these conditions, it would be desirable to identify agents that can antagonize the actions of the responsible growth factors.
One of the most direct approaches to the identification of growth factor antagonists has entailed the use of assays based upon the binding of radiolabeled ligands to cellular receptors. Such assay systems are quite laborious and time consuming, however, and determination of the specificity of a given antagonist requires the use of a number of different radiolabeled growth factors and membrane receptor preparations.
An even more serious drawback to such assays is that they can detect only antagonists which act at the receptor level and interfere with growth factor binding. As noted above, however, a complex sequence of events occurs after a growth factor binds to its receptor. Intervention at multiple points by appropriate antagonists may thus be possible, but antagonists acting at points other than at the receptor cannot be identified by radioligand/receptor assays.
There is therefore a need for a more broadly-based growth factor antagonist screen that could identify a much wider range of antagonists, regardless of their locus of action.


There is provided an improved metallization stack structure and a method for fabricating the same so as to produce a higher electromigration resistance and yet maintain a relatively low resistivity. The metallization stack structure includes a pure copper layer sandwiched between a top thin doped copper layer and a bottom thin doped copper layer. The top and bottom thin doped copper layers produce a higher electromigration resistance. The pure copper layer produces a relatively low resistivity.

1. Field of the Invention
This invention relates generally to semiconductor integrated circuit devices having interconnects and more particularly, it relates to an improved metallization stack structure which has a higher electromigration resistance but yet maintains a relatively low resistivity of ultra large-scale-integration (ULSI) interconnects.
2. Description of the Prior Art
As is generally known to those skilled in the art, aluminum-based alloys have been used as an interconnection material in semiconductor integrated circuit devices for the past three decades. As the size dimensions of the integrated circuit devices are becoming smaller and smaller and decreasing down to a deep sub-micron range (i.e., 0.25 .mu.m and beyond) there has been raised a question as to the feasibility of using aluminum-based alloys as an interconnection material due to their two limiting factors. The first limiting factor of aluminum and aluminum-based alloys is because of a problem that disconnection or failure of the interconnection is liable to occur due to electromigration damage (EMD) and/or stress migration.
As defined herein, the term "electromigration" refers to a diffusion phenomenon which is based on an interaction between metal atoms in an interconnection (a metal line) and electrons moving in the interconnection. In particular, the electromigration is a phenomenon where the metal atoms migrate in the same direction as that of the electron movement. When this occurs, the resultant metal atom migration will cause an atomic vacancy or void to be formed at the location from which the metal atoms have moved, or will cause a hillock to be built up at the location where the metal atoms accumulate. When such voids are formed, the local cross-sectional area of the metal line will be decreased and the local current density in the metal line will be increased.
As explained in a paper article entitled "Copper Metallization for ULSI and Beyond" which was written by S. P. Murarka and S. W. Hymes, Solid State and Materials Sciences, Vol. 20, Issue 2, p. 87,1995, electromigration is caused by mass transport manifested as diffusion under a driving force. When a metal line is under the influence of an electric field and the current density is large enough (.gtoreq.10.sup.4 A/cm.sup.2), the current can displace the metal ions and move them away from their equilibrium positions. The enhanced and directional mobility of atoms are caused by (1) the direct influence of the electric field on ionized metal atoms, and (2) the collusion of electrons with atoms, leading to a momentum transfer (called electron-wind effect) and metal atom movement. The atomic flux moves in the direction of electron flow. At the same time, vacancies move in the opposite direction and form a vacancy flux. Whenever a gradient in temperature, grain size, geometric features, current density, and crystal orientation of grains, etc., occurs, metal atoms will be accumulated or depleted, forming hillocks or voids, which eventually grow large enough to cause metal line open or short failures.
The atomic flux due to electromigration can be expressed mathematically as follows: ##EQU1## where D is the atomic diffusivity N is the atomic density
Z is the effective charge on the moving ion PA1 o is the metal resistivity PA1 q is the electron charge PA1 j is the current density PA1 k is Boltzmann's constant PA1 T is temperature in degrees Kelvin
In Table I below, there is shown the electromigration parameters for the bulk materials of silver (Ag), aluminum (Al), gold (Au), and copper (Cu). As can be seen, the failures due to electromigration appear to be the worst in aluminum.
TABLE I __________________________________________________________________________ Electromigration parameters Dif.para. D(cm.sup.2 /s) Z*.rho.D(.mu..OMEGA.cm.sup.3 /s) Metal Z* .rho.(.mu..OMEGA.-cm) D.sub.0 (cm.sup.2 /s) O(eV) @100.degree. C. @100.degree. C. __________________________________________________________________________ Ag 9.4-23.4 1.6 1.89 2.01 1.1 .times. 10.sup.-26 2.84-7.0 .times. 10.sup.-25 Al 6.5-16.4 2.7 1.71 1.46 2.1 .times. 10.sup.-20 3.62-9.1 .times. 10.sup.-19 Au 5.9-7.4 2.4 0.67 1.96 2.2 .times. 10.sup.-27 3.05-3.8 .times. 10.sup.-26 Cu 3.7-4.3 1.7 0.78 2.19 2.1 .times. 10.sup.-30 1.3-15 .times. 10.sup.-29 __________________________________________________________________________
The second limiting fact or of aluminum and aluminum-based alloys is its resistivity. The pure aluminum has resistivity of about 2.7 .mu..OMEGA.-cm, which is significantly higher than that of pure copper (1.7 .mu..OMEGA.-cm). For practical integrated circuit applications, in order to increase its electromigration resistance, actual interconnects are made of aluminum alloys containing 0.5 to 2 weight-percent copper, which increases its resistivity to 3 to 3.5 .mu..OMEGA.-cm. In addition, the use of tungsten (W) plugs as vertical interconnects and titanium/titanium nitride as a barrier layer increases the effective final interconnect resistivity to as high as 4.5 to 5 .mu..OMEGA.-cm. Higher resistivity leads to higher RC delay (signal propagation delay) and limiting circuit speed.
In Table II below, there is shown a comparison of properties for different low-resistivity metals consisting of silver (Ag), aluminum (Al), gold (Au), copper (Cu), and tungsten (W). All the properties that must be considered in applications of these metals as interconnects in integrated circuits have been listed. As will be noted, silver offers the lowest resistivity, about 5% lower than that of copper. However, silver has poor electromigration resistance (see Table I). Also, silver does not adhere to silicon dioxide (SiO.sub.2) or other dielectrics, and it diffuses in the silicon dioxide at a much faster rate than copper (especially under bias).
TABLE II ______________________________________ Metals Property Cu Ag Au Al W ______________________________________ .rho.(.mu..OMEGA.-cm) 1.7 1.6 2.4 2.7 5.7 Melting point (.degree.C.) 1085 962 1064 660 3387 Atomic weight (amu) 64 108 197 27 184 TCR(.times.10.sup.3 /K) 4.3 4.1 4 4.5 4.8 TEC(.times.10.sup.3 /K) 17 19.1 14.2 23.5 4.5 Thermal conductivity(W/cm) 4.0 4.25 3.15 2.38 1.74 Special heat capacity(J/kg K) 386 234 132 917 138 Corrosion in air poor poor excellent good good Adhesion to SiO.sub.2 poor poor poor good poor Deposition sputtering yes yes yes yes yes evaporation yes yes yes yes yes CVD yes ? ? yes(?) yes Etching dry ? ? ? yes yes wet yes yes yes yes yes ______________________________________
In view of the foregoing, there has arisen a need for developing of new interconnection materials which will posses a higher degree of resistance to electromigration damage. From the above Tables I and II, it can be noted that copper is the best choice for use as interconnect material in integrated circuits. Copper has lower resistivity (about 30% lower than that of aluminum). In addition, the melting point for copper is more than 450.degree. C. higher and its atomic weight is more than two times heavier than that of aluminum. These properties indicate that copper will have a higher electromigration resistance than aluminum-based alloys. As a result, this would allow higher current density and narrower line width in copper interconnects, thereby improving current density and reducing interconnect resistance and capacitance, which will result in higher circuit speed.
Further, in a published article entitled "Electromigration-resistant Cu--Pd Alloy Films" which is authored by C. W. Park and R. W. Vook, Thin Solid Films, 226(1993), pp. 238-247, it is stated that copper is a prospective material for metal interconnects in microelectronic circuits since it has a high resistance to electromigration damage and a low electrical resistivity. Moreover, in order to achieve an even higher resistance to electromigration damage it was found that this could be accomplished by alloying copper (Cu) with a small amount of palladium (Pd). While the doped copper alloy exhibited a better electromigration reliability than pure copper, it suffered from the disadvantage of possessing a higher electrical resistivity than the pure copper.
Accordingly, there still exists a need of an interconnect structure which has a higher electromigration resistance but yet maintains a relatively low resistivity. The present invention represents a significant improvement over the Cu--Pd alloy structure discussed in the aforementioned Park et al. paper.

Method for fabricating a metallization stack structure to improve electromigration resistance and keep low resistivity of ULSI interconnects


A method and system for digital cameras provides improved automatic exposure control, improved automatic white balance, improved color interpolation, improved automatic gamma correction, and improved progressive edge enhancement. These improvements are preferably implemented in CMOS semiconductor technology for faster speed.

Digital imaging systems have created a revolution in photography and cameras. A digital camera is similar to a film camera except that the film is replaced with an electronic sensor. The sensor is comprised of an array of photo detectors that change the photons that strike them into electrons providing a signal at each pixel proportional to the number of photons, or the amount of light at each pixel. Presently, most consumer digital cameras employ Charge Coupled Device (CCD) or Complementary Metal Oxide Semiconductor (CMOS) sensors. To facilitate the collection of light, many of the sensors employ a small lens-like structure covering each pixel, which is called a microlens. These microlenses are typically made by forming a layer of photoresist that is placed upon the pixel plane.
The image sensors used in digital imaging are inherently monochrome devices, having no color discriminating ability associated with each detector. For this reason, the sensors typically employ a Color Filter Array (CFA) inserted between the microlens and each active portion of the pixel structure, the photodiode. Typically, the CFA is constructed to assign a single color to each pixel. Digital camera manufacturers often choose among a variety of CFA architectures, usually based on different combinations of primary colors (red, green, blue) or complementary colors (cyan, magenta, yellow). Regardless of the particular CFA used, the overall aim is to transfer only a single color of interest, so that each pixel sees only one color wavelength band.
One of the most popular and ubiquitous CFA patterns is called the Bayer Pattern, which places red, green and blue filters over the pixels, in a checkerboard pattern that has twice the number of green squares as red or blue. The theory behind the Bayer Pattern is that the human eye is more sensitive to wavelengths of light in the green region than wavelengths representing red and blue. Therefore, doubling the number of green pixels provides greater perceived luminance information and detail, while natural color representation for the human eye.
When subjected to light, the image sensor photo diode converts incident photons to electrons. This conversion enables analog electronic circuitry to process the image "seen" by the sensor array. The electrons gathered by these sensors are stored in small capacitors that are read out as a series of varying voltages, which are proportional to the image brightness. An Analog to Digital Converter (ADC) conditions these voltages for processing by a computer within the camera. The data is processed to form a picture of the image "seen" by the sensor array. The sensor is only one part of the digital camera. An associated processor controls the sensor and processes the data from the sensor to achieve high quality output images. The tasks performed by the processor include Automatic Exposure Control (AEC), Automatic White Balance (AWB), color interpolation or "demosaicing", color correction, contrast enhancement or gamma control, and noise reduction. A properly tuned sensor/processor combination results in superior digital camera images.
In many designs, a mechanical shutter is used in the same way that it is used in a film camera—to gate the light that is allowed to reach the sensor or film. Many digital cameras use what is called an electronic shutter, which allows the control of when and for how long the sensor gathers light through electronic control signals to the sensor. Proper design of the automatic exposure control algorithm ensures high quality images.
In a single sensor camera using a color filter array, one type of algorithm implemented by the processor is called a color interpolation or demosaicing algorithm, which is used to derive complete color data for each pixel. Demosaicing algorithms analyze neighboring pixel color values to determine the resulting color value for a particular pixel, thus delivering a full resolution image that appears as if each pixel's color value was derived from a combination of the red, blue, and green primary colors (if RGB colors are used). Thus, the assembled image can exhibit natural gradations and realistic color relationships.
Automatic white balance (AWB) algorithms are used to set the overall color 'tone' of a digital image, correcting for different colors of illumination and for color biases inherent in the sensor. Other types of algorithms specifically for color correction allow the digital data to be further processed to achieve a particular color and intensity (or shade) associated with a specific pixel. Some set a default saturation level high, producing extremely bright, sometimes unnatural colors. Others choose a neutral, more realistic saturation, for greater subtlety and color accuracy. A gamma correction algorithm is used in many digital cameras to tune the image histogram, attempting to make details in both light and dark portions of the image visible.
As digital imaging becomes more prevalent, industry is striving to develop images and video with better resolution and color accuracy. The quality of an image produced by a digital camera can be measured in several ways such as resolution and dynamic range. In the most basic sense, the resolution of a digital camera can be stated to be the total number of pixels used. For example, a camera with a sensor that has 800 by 1000 pixels can be said to have 800,000 pixels of total resolution. As stated, the resolution is a quality of the camera mechanism. In an image, the resolution is the limit of the ability to depict fine lines, sharp edges, and other details in the original scene. Resolution depends on the optical system (lens, filters, etc), the number of pixels, and the manner of processing the digital signal.
The dynamic range relates to both the accuracy of the A/D converter that changes the analog voltage representing a pixel brightness to a digital number. Typical cameras have A/D converters of 10 to 12 bits or 1024 to 4096 different dissemble levels. Better cameras may have higher A/D resolution. The dynamic range is the largest possible signal containing information, divided by the smallest possible signal that is distinguishable from noise, usually expressed in decibels.
The broader the dynamic range of the camera, the easier it is to differentiate small gradations in brightness or color. Noise can come from several different places including optical noise from lens flare, thermal and electronic noise from the power supply, electronic circuitry and the sensor itself. Unique to digital cameras, a large component of the noise is thermally generated within the sensor. Cooling the sensor can reduce this noise but electronically cooling the sensor with a Thermo-Electric (TE) cooler is both expensive and consumes quite a bit of power. In total, the dynamic range will interpret into a digital camera's ability to observe fine gradations in the darkest shadow areas of an image or equivalently in the brightest highlights.
In taking a digital image, one aim is to achieve images in which objects are exposed properly and are not too bright or too dark. Commonly, this is achieved through moving the digital information histogram to an optimal point within the bounds of the maximum and minimum output signal levels of the system. Another related aim is to achieve images that are properly exposed and which exhibit a high signal-to-noise ratio. Stated another way, the aim is to acquire properly-exposed images that do not show many noise artifacts.
There is a continuing need to develop improved digital imaging systems and processes to capture higher quality images and video. It is possible to capture higher quality images and video through improving the digital processes that manipulate the raw data acquired from the photo sensor array. In addition, it is possible to improve the operation of digital image and video systems through streamlining the overall process architecture. CMOS sensors, having many cost, power, and circuit advantages over CCD sensors, tend to have poorer signal-to-noise and dynamic range than CCDs. Improved digital processes are of great value in avoiding unnecessary noise in the final image from a CMOS sensor, and making best use of its available dynamic range.

Digital image processing using white balance and gamma correction


A display method, and a user terminal and a system for transmitting and receiving data using the same, are disclosed. The display method includes sequentially receiving first data from an external server, and displaying the received first data in the order of receiving the first data; discontinuing to receive un-received data among the first data, receiving the second data from the external server, and displaying the received second data on a screen; and continuing to receive the discontinued data from the external server.

1. Field of the Invention
The present invention relates generally to a display method, a user terminal and a system for transmitting and receiving data using the same, and more particularly, to a display method to receive and display data satisfying a user's intention, and a user terminal and a system for transmitting and receiving data using the same.
2. Description of the Related Art
Recently, with the growing popularity of multimedia devices, the number of contents used in the multimedia devices has dramatically increased. The increase of contents enables a user to select and use various contents.
Among with such positive aspects, such as providing abundant contents, negative aspects also appear. One of the negative aspects is an excessive amount of contents. A great amount of contents may enable a user to have a huge selection of contents, but may confuse a user as well. Since the contents are typically displayed on a limited area of a display, the number of pages required to display the contents increases and the font size of contents is reduced.
Another negative aspect is over-charging due to unnecessary contents. If a user receives contents in real-time, unnecessary contents may also be transmitted to the user, thereby wasting money by receiving unnecessary contents.
Accordingly, there is a need for methods to transmit only contents or data to a user that satisfies the user's intention.

Display method, user terminal, and system for transmitting and receiving data using the same


An acoustic coupler for a hearing device. The hearing device including a microphone. The acoustic coupler includes an earphone receptacle formed to releasably engage an earphone therein and a securing feature formed to detachably engage the coupler to the hearing device in proximity to the microphone.

1. Field of the Invention
The present invention relates generally to hearing prostheses, and more particularly, to an acoustic coupler that interfaces with an external component of a hearing prosthesis.
2. Related Art
Hearing loss, which may be due to many different causes, is generally of two types, conductive and sensorineural. Conductive hearing loss occurs when the normal mechanical pathways for sound to reach the cochlea are impeded, for example, by damage to the ossicles. Individuals suffering from conductive hearing loss typically have some form of residual hearing because the cochlea is undamaged. As a result, individuals suffering from conductive hearing loss typically receive an acoustic hearing aid that amplifies received sound to compensate for the conductive hearing loss.
Sensorineural hearing loss occurs when there is damage to the inner ear or the neural pathways from the inner ear to the brain. As such, those suffering from sensorineural hearing loss are typically unable to derive suitable benefit from hearing prostheses that cause mechanical vibrations of the cochlea. In contrast, cochlear implants deliver electrical stimulation to the neural pathways in the cochlea.
Users of hearing prostheses often seek to listen to music from portable devices. Typically, electrical signal communication is established between a sound processor of the hearing prostheses and the portable device to feed the music electronically to the hearing prosthesis. That is, output from the portable device typically bypasses any microphone of the hearing prostheses.


A sleep prevention device while driving a vehicle including a housing member having an interior compartment; and the interior compartment includes a movable cord member with a distal end and a proximal end having a first contact member on the cord member. The interior compartment also includes two spaced-apart second contact members for engagement by the first contact member. The sleep prevention device further includes an earpiece assembly having an earpiece housing member with an alarm member therein connected to a speaker member in the earpiece housing. The distal end of the movable cord member is connected to the earpiece assembly. The first contact member moves in either a forward direction or a rearward direction as the driver's head moves as the driver starts to doze or fall asleep such that the first contact member moves and engages one of the second contact members in order to activate the alarm member and produce an alarm sound in the driver's ear from the speaker member of the alarm member for awakening the driver from his/her dozing or sleeping state.

The National Highway Traffic Safety Administration of the Untied States estimates that on average each year approximately 100,000 vehicular accidents are caused by sleepy (dozing or falling asleep at the wheel) drivers. Drowsy driving kills yearly about 1,500 (drivers and passengers) and causes 71,000 bodily injuries. For example, if a drowsy driver is driving at 65 mph and nods off for just three (3) seconds, the driver will have traveled the length of a football field, if the driver does not hit something first. A survey conducted by the National Sleep Foundation found that 17 percent of the drivers polled indicated they had fallen asleep at the wheel of their vehicle within the past year. The state of New Jersey during 2003 has enacted "Maggie's Law" which authorizes a vehicular homicide conviction if a driver is in a fatal crash after at least 24 sleepless hours. The New Jersey statute is the first such law enacted in the United States.
There remains a need for a sleep prevention device while driving that responds to a driver when dozing or falling asleep at the wheel of moving vehicle, as the driver's head moves forward or rearward, in order to sound activate a alarm in the driver's ear. Additionally, the sleep prevention device should include an ear piece element having the alarm mechanism within the ear piece to wake the driver.


A combined trouser press and ironing board assembly is disclosed. It comprises a heatable pad (14) against which a surface of a pressure plate (4) is clampable in a first position to sandwich a garment to be pressed therebetween. The pressure plate (4) is mounted by means which allow said plate (4) to be moved relative to the heatable pad (14) into a second ironing position in which the pressure plate (4) extends laterally outwardly relative to the heatable pad (14) so that the surface thereof which was facing the heatable pad (14) in its first position now provides the surface on which a garment can be placed for ironing.

1. Technical Field
This invention relates to an apparatus or assembly that can be used as a trouser press but is capable of conversion for use as an ironing board.
2. Description of Related Art
Trouser presses in which a pair of trousers can be sandwiched and clamped between a heated pad and a pressure plate are known. Ironing boards on which garments can be ironed are also known. However, this requires two separate pieces of equipment so there is a need for an apparatus that combines both of these functions into a single assembly.
It is also quite difficult to correctly position a pair of trousers in a conventional trouser press so that the creases are straight and in the correct place. It is therefore desirable to have a pressing apparatus that enables a pair of trousers or other garment to be positioned more easily prior to being pressed.


A fixture plate includes a base having a contact face configured to support a dental model having a model identifier on a bottom surface. A bore extends through the base to one or more channels formed in the contact face and that extend from the bore. A viewing port extends through the base and has a transparent material inserted therein to seal the viewing port at the contact face. The viewing port and the transparent material enable the model identifier to be accessed from underneath the contact face when the dental model is on the contact face. A protrusion extends from the contact face and is configured to interface with an aperture of the dental model to retain the dental model in a specific orientation. The channels are configured to provide a suction force applied through the bore to hold the dental model against the contact face.

The present disclosure relates generally to manufacturing dental appliances. More specifically, the present disclosure relates to a system for holding dental models during manufacturing of dental appliances, such as dental aligners for repositioning teeth of a user.
Dental aligners may be worn by a user receiving orthodontic treatment. Some dental aligners are fabricated by thermoforming material to a dental model. After thermoforming the material to a dental model, the material can be marked and the formed aligner cut and removed from the dental model. The dental model with the thermoformed material should be securely retained to ensure that components of a manufacturing system accurately interact with the dental model and the material thermoformed thereon.


A multi-function day/night observation, ranging, and sighting device includes a single objective lens and a single eyepiece lens and provides an image of a scene. The single objective lens leads to a visible-light first optical path and to an invisible-light second optical path. The invisible-light second optical path includes an image intensifier tube providing a visible image. The first-and second optical paths converge with visible images provided by each pathway being overlaid at a reticule plane. A single light path leads from the reticule plane to the eyepiece lens. A laser provides a pulse of laser light projected into the scene via the single objective lens, and the image intensifier tube is used as a detector for a portion of the laser light pulse reflected from an object in the scene in order to provide a laser range finding function. The device includes a light-emitting display visible through the eyepiece lens and providing ranging information superimposed over the image of the scene as seen by a user of the device. Methods of the device's operation are also disclosed.

1. Field of the Invention
The present invention is in the field of image-magnifying viewing devices (i.e., telescopes) which can be used both in the day time to obtain a magnified view of a distant scene, and which can also be used at night or under other conditions of low ambient lighting in order to view such a distant scene. The view of the distant scene is magnified, and at night is also intensified or amplified by use of an image intensifier tube to provide a visible image when the scene is too dark to be viewed with diurnal vision. Accordingly, this invention relates to telescopes and other such viewing devices which may be used both in day and at night for observation and surveillance.
The present invention also relates to laser range finding apparatus and method. Such laser range finding apparatus and methods ordinarily project a pulse of laser light into a scenes The laser light pulse illuminates objects in the field of view and is partially reflected from at least one object in the scene whose distance from the observer is to be determined. In order to select this one object, the device may include a reticule and the laser light pulse may be of "pencil beam" configuration. The reflected portion of the laser light pulse is detected at the device, and the transit time for the laser light pulse to travel to and from the object is used to calculate a range to the object using the speed of light as a measuring standard.
This invention is also in the field of telescopic weapon aiming sights which provide a user with an aiming reticule, and which include provisions for bore-sighting the relative position of the reticule on a scene to the trajectory of a projectile. In other words, the telescopic device allows adjustments to place the reticule image on the viewed scene at the location where a bullet or other projectile will strike at a particular range.
2. Related Technology
A conventional day/night telescopic sight is known in accord with U.S. Pat. No. 5,084,780, issued Jan. 28, 1992 to E. A. Phillips. The Phillips patent appears to teach a telescopic day/night sight which has several alternative embodiments According to one embodiment set out in the Phillips patent, such a telescopic sight includes a single objective lens behind which is disposed an angulated dichroic mirror. This mirror divides light coming into the sight via the objective lens into two frequency bands. Light of longer wavelengths (lower frequencies) is allowed to pass through the dichroic mirror to an image intensifier tube. This image intensifier tube operates in the conventional way familiar to those ordinarily knowledgeable about night vision devices. That is, the image intensifier tube provides a visible image which replicates a dim image or an image formed by invisible infrared light within the so-called near infrared . Thus, the longer wavelength band which passed through the dichroic mirror includes the infrared portion of the spectrum and provides to the image intensifier tube the frequencies of light to which the tube is most responsive.
The visible portion of the light entering the Phillips sight via the objective lens is reflected by the dichroic mirror into an optical system leading to a combiner and to an eyepiece. At the combiner, the image provided by the image intensifier tube is superimposed on the image from the visible-light channel of the sight, and the resulting combined image is presented to a user of the sight via the eyepiece.
A possible disadvantage of the Phillips sight as described above is that the angulated dichroic mirror can introduce both parallax, astigmatism, and color aberrations into the image provided to the user. Thus, slight movements of the sight may cause the user to experience some shifting of the image along a line parallel with the angulation of the mirror, while the image does not shift along a line perpendicular to this angulation. In other words such an angulated dichroic mirror may result it the slight jiggling inherent in a hand-held telescope or weapon sight amplifying the apparent movement of the image in at least one direction. This effect can be disconcerting for the user of the device.
Other versions of the Phillips sight use a separate objective lens for both the day channel and the night channel of the sight. These versions would not appear to suffer from the same possible parallax problem described above with respect to the versions using the dichroic mirror. However, the versions of Phillips sight with two objective lenses suffer from an increased size, weight, and expense because of the additional optics and larger housing required to mount and protect these optics.
In each case with the sight disclosed by Phillips, the optical channels for the night sight and the day sight are laterally offset relative to one another. These two offset optical channels are parallel, and the image from these channels is combined for presentation at the eyepiece. However, in each case, the sight taught by Phillips requires separate laterally offset optical channels, and presents the problem of correctly and precisely superimposing the image from these two channels for the user of the sight.
Another consideration with the Phillips sight is the mechanism and size of housing required for effecting windage and elevation adjustments of the reticule. Some versions of the Phillips sight use a reticule plate, while others use an injected reticule (i.e., provided by a projector for a lighted reticule "dot" which is superimposed on the image of the viewed scene). In each case, the objective lens of the device receives a larger scene image (i.e., field of view) than is provided to the user, and the reticule is moved about within this field of view in order to provide windage and elevation adjustments. However, it is often desirable for the user of such a sight to perceive no apparent change in the centering of the reticule on the field of view. This results in a smaller imaged field of view with a centered reticule pattern moving about in a larger field of view provided by the objective optics. Understandably, optical systems of this type suffer from increased size and weight because of the larger objective optics.
Yet another disadvantage of sights of this conventional type is that the mechanism for moving the reticule is inherently located near the rear of the sight. This location for the reticule mechanism results in the housing of the sight being undesirably large at a location where clearance must be provided for the action mechanisms of many weapons.
Another conventional day/night weapon sight is known in accord with U.S. Pat. No. 5,035,472, issued Jul. 30, 1991 to Charles L. Hansen. The U.S. Pat. No. '472 appears to disclose a sighting device including a number of dichroic reflectors, which divide the incoming light into spectral bands. The visible one of the spectral bands passes to an eyepiece for viewing by a user of the device. Another of the spectral bands of light passes to an image intensifier tube. A visible image provided by this image intensifier tube then passes to the eyepiece. Yet another spectral band passes to a focal plane array device, such as to a CCD. The CCD is associated with a display device, such as a CRT. The image from the CRT then passes to the user via the eyepiece.
The device disclosed in the U.S. Pat. No. '472 appears not to provide laser range finding. No provisions appear to be made for a reticule usable in sighting by use of this device. Focusing and adjustment of a reticule position for windage and elevation also appear not to be addressed by the U.S. Pat. No. '472.
Conventional laser range finders have also been known for a considerable time. One exemplary version of such a device is known as the MELIOS. This device uses viewing optics, a laser having a projection optical system, and a detector having a separate receiving optical system, all directed at a scene in which an object is located having a range to be determined. In operation, the laser provides a pulse of laser light, and this is projected into the scene via the projection optics. This laser light illuminates the object, and a portion of the laser light is reflected back toward the device. Part of the reflected laser light returning to the device is captured by the receiving optical system, and is directed to a detector. The device includes a timer starting when the laser light pulse is transmitted and stopping when the returning laser light is detected. A calculator portion of the device uses the elapsed time from transmission of the laser light pulse until detection of the returning reflected laser light to calculate the distance to the object.
Another conventional laser range finder is known as the Commander's Viewer Sight. This device uses a catadioptric optical viewing system, and places separate optics for projecting and detecting the laser light in the central obscuration of the viewing optical system. Thus, the viewing optics and laser range finder optics (i.e., projector and detector optics) are coaxial in this sight, but they are nevertheless separate optical structures.

Multi-function day/night observation, ranging, and sighting device and method of its operation


A motor base includes a bottom plate and at least one vibration reduction unit. The bottom plate has opposite top and bottom surfaces. A shaft-coupling portion is arranged on the top surface. The at least one vibration reduction unit encloses the shaft-coupling portion. Each of the at least one vibration reduction unit includes at least one protrusion and at least one groove. The at least one protrusion is arranged on one of the top and bottom surfaces. The at least one groove is correspondingly arranged on the other one of the top and bottom surfaces.

1. Field of the Invention
The present invention generally relates to a motor base and, more particularly, to a motor base that is designed to reduce the noise of the motor by reducing the reverberation energy resulting from the vibration of the motor.
2. Description of the Related Art
Referring to FIG. 1, Taiwan Patent No. 1318559 discloses a motor base 7 of a conventional motor that is designed to reduce the reverberation energy resulting from the vibration of the motor. The motor base 7 includes a base plate 71 having a plurality of annular grooves 72. A shaft tube 711 is mounted on the base plate 71 to support a rotating impeller. The annular grooves 72 enclose the shaft tube 711 to reduce the reverberation energy resulting from the rotation of the impeller.
Due to the arrangement of the annular grooves 72 on the base plate 71, the parts of the base plate 71 which form the annular grooves 72 are thinner, resulting in a weaker structural strength of the motor base 7. As a result, when the motor base 7 is mounted with components such as the impeller, a stator or a circuit board, the motor base 7 may not sufficiently support the motor. Disadvantageously, the quality of the motor is poor, and the service life of the motor is shortened.
To solve the problem, China Patent Application No. 201020004026.0 discloses a fan frame 8 that is designed to reduce the vibrational force during operation. The fan frame 8 includes a base plate 81 and a separating portion 82. A shaft-coupling portion 811 is mounted on the base plate 81. The separating portion 82 surrounds the shaft-coupling portion 811 to reduce the vibrational force and noise. The separating portion 82 has a greater thickness than other parts of the base plate 81, achieving a reinforced structural strength of the fan frame 8.
Although the separating portion 82 provides both advantages of strengthening the fan frame 8 along with relieving the vibrational force placed upon the fan frame 8, the ability of the separating portion 82 to reduce the vibrational force is not as effective as the annular grooves 72 of the motor base 7 due to the fact that the separating portion 82 has a greater thickness than the rest of the portions of the base plate 81.
Referring to FIG. 3, Taiwan Patent No. 483658 also discloses a conventional fan frame 9 capable of reducing the vibrational force during operation. The fan frame 9 includes a base 91 and a plurality of bridging members 92. The base 91 is mounted with a shaft tube 911. The bridging members 92 are connected between the base 91 and an outer ring 93. Each bridging member 92 has a bent section 921 capable of reducing the internal and external vibrations of the fan frame 9.
Due to the facts that the bridging members 92 are connected to the outer ring 93 and that the bent section 921 is arranged on a respective bridging member 92, the bridging members 92 are not connected to the base 91 in a secure manner due to the bent sections 921. In addition, since the bent sections 921 are positioned on the bridging members 92 only, the bridging members 92 cannot be arranged on the entire periphery of the base 91. Consequently, the bent sections 921 cannot omnidirectionally reduce the reverberation energy resulting from the vibration of the shaft tube 911.

Sunonwealth Electric Machine Industry Co., Ltd.


A method, an apparatus, a computer readable recording medium, and a medical imaging system are provided for segmenting an image of an object from an image of an organ. The method includes: generating a reference model of the object by using a priori knowledge related to the object of the organ; determining whether the first image includes a first area in which a shape of the object is unidentified; and in response to determining that the first image excludes the first area, segmenting a second image of the object from the first image, and in response to determining that the first image includes the first area, estimating a progression direction of the first area from the reference model to segment the second image from the first image.

1. Field
The following description relates to a method, a computer-readable storage medium, an apparatus, and a medical imaging system for segmenting an image of an object from an image of an organ.
2. Description of the Related Art
For patient-specific organ modeling, necessary information may be obtained from a medical image of the patient such as a computed tomography (CT) image or a magnetic resonance imaging (MRI) image. This process, which isolates an object from pictures of an organ, is referred to as a segmentation. For this image segmentation, methods of segmenting an image of a desired object from an image of an organ based on a known shape of the organ or directly segmenting an object from an image of an organ of a patient by a user have been used. Additionally, methods of using well-known shapes of organs have been used.
It is difficult to segment a complicated organ that has a tree structure such as a liver or a blood vessel of a kidney. This task is difficult because of the complexity of shapes of organs, and also because information about organs disappears or overlaps with one another due to problems related to resolution, timing requirements, and/or other characteristics of medical imaging apparatuses. Nevertheless, various segmentation methods have been proposed to provide operational solutions to these problems due to the importance of imaging organs such as blood vessels.
However, in currently existing approaches, factors such as the disappearance of information about items such as blood vessels or the like or issues related to overlapping parts is not considered, and hence such information is not automatically used to help address the problems discussed above.

Method, apparatus, and medical imaging system for segmenting image of object from image of organ


A hose construction, hose coupling therefor and methods of making the same are provided, the hose construction comprising a combination of a hose coupling and a tubular hose having one end thereof clamped in an annular recess of the coupling, the coupling having a longitudinal axis and comprising a tubular insert portion inserted into the end of the hose and having an external peripheral surface that is substantially parallel to the longitudinal axis and a tubular ferrule portion disposed in substantially concentric and spaced relation about the insert portion to define the annular recess therebetween and being radially inwardly deformed toward the longitudinal axis so as to clamp the end of the hose between the ferrule portion and the insert portion, the ferrule portion having a plurality of inwardly directed and axially spaced apart annular ridges deformed into the end of the hose, the ferrule portion comprising an outer generally cylindrical section having an inner peripheral surface provided with opposed ends and a separate ridged section held within the outer section by the ends thereof to define a self-contained ferrule portion and having an outer peripheral surface disposed in engagement with the inner peripheral surface of the outer section and having an inner peripheral surface defining the ridges of the ferrule portion.

1. Field of the Invention
This invention relates to a new hose coupling and to of the hose coupling and a hose as well as to new methods of making the same.
2. Prior Art Statement
It is known to provide a combination of a hose coupling and a tubular hose having one end thereof clamped in an annular recess of the coupling, the coupling having a longitudinal axis and comprising a tubular insert portion inserted into the end of the hose and having an external peripheral surface that is substantially parallel to the longitudinal axis and a tubular ferrule portion disposed in substantially concentric and spaced relation about the insert portion to define the annular recess therebetween and being radially inwardly deformed toward the longitudinal axis so as to clamp the end of the hose between the ferrule portion and the insert portion, the ferrule portion having a plurality of inwardly directed and axially spaced apart annular ridges deformed into the end of the hose. For example, see the Foster U.S. Pat. No. 4,653,779.
It is also known to form the ferrule portion with an outer generally cylindrical section and separate inner ridged section respectively having surface means disposed in engagement with each other during the deforming of the ferrule portion toward the insert portion. For example, see the Lusher et al, U.S. Pat. No. 2,314,000, and the Jones U.S. Pat. No. 4,212,487.

Method of making hose coupling with ferrule end bent over insert


The present invention relates to devices, methods, and kits for quickly and easily measuring and monitoring the pH of aquatic environments, such as lakes, streams, drinking waters, fisheries, aquariums, pools, hot-tubs, and spas. The current invention includes devices that are reusable and capable of monitoring the pH in a reversible fashion, thereby allowing continuous pH sensing without a need for the user to physically perform pH tests. Operation of the invention involves placing the device into the aquatic environment and optically detecting a color change in the membrane, for example, by looking at the device, when a pH measurement is desired. In addition, the device is both inexpensive and reusable, allowing the user to monitor the pH of various aquatic environment at minimal costs.

1. Field of the Invention
The invention relates generally to monitoring aspects of water chemistry and more specifically to methods and reusable devices for detecting and continuously monitoring pH of aquatic environments.
2. Background Information
The balance of various chemical components or parameters in an aquatic environment is generally referred to as "water chemistry". Water chemistry is highly determinative of the health and safety of an aquatic environment and the suitability of water for various uses. In many aquatic environments such as fisheries, lakes, drinking water, including recreational waters such as pools, spas, and hot tubs, maintenance of conditions suitable for use, potability, healthy bathing, etc., as well as an aesthetically pleasing environment, is highly dependent on a proper balance of water chemistry parameters. Maintaining a proper water chemistry balance requires constant monitoring and is necessary in preventing the unwanted effects of altered water chemistry, such as skin and eye irritation of bathers, cloudy water, staining and corrosion of pool equipment, and formation of unsightly mineral deposits. Additionally, monitoring and maintaining proper water chemistry in drinking water or environments containing aquatic life (e.g., fish), such as fisheries or aquariums, is vital to ensuring conditions that ensure a healthy water supply, as well as ensure the health and survival of the aquatic life present. For example, altered levels of ammonia or nitrogen, or incorrect pH levels can result in discolored water, algae blooms, outbreak of disease, and fish loss. As such, accurately determining various aspects of water chemistry is of critical importance for determining the suitability of water for various applications, as well as maintaining the health and safety of a water sample.
Water pH is one of the most important parameters of water chemistry. The pH scale is a measure of the acidity or amount of free hydrogen ions in the water. The pH scale extends from 0 to 14, with a pH value of 7.0 corresponding to a neutral pH. As the pH moves lower than 7.0, the water becomes increasingly acidic, and as the pH moves higher than 7.0, the water becomes less acidic and more basic. Because pH is measured with a logarithmic scale, very small changes in the value indicate large changes in hydrogen ion concentration. For example, a change of one pH unit corresponds to a ten fold difference in the number of free hydrogen ions. The pH value of aquatic environments such as aquariums, pools, and spas is vital not only because it is itself an important parameter, but also because other water chemistry parameters (e.g., ammonia, total alkalinity, chlorine, and phosphates) are dependent on the pH value. Because of the importance of this parameter, the pH of aquariums, pools, and hot-tubs must be monitored frequently to adjust accordingly to small changes in the pH values.
Several methods are currently used to test the pH value of aquatic environments. Perhaps the most common method is a method utilizing solutions containing indicator dyes, which change color corresponding to the pH of the water sample. Such methods include removing a small sample of water from the aquatic environment and adding a dye solution calibrated to test the pH. The combination of the dye solution and the water sample is allowed to develop a color, and the color of the water-dye mix is compared to reference colors corresponding to pH values. The solutions are then discarded following comparison of the water-dye mix to reference colors and determining the pH of the sample. This method is inexpensive, making it popular for residential applications, but is time consuming and user-intensive. The user must first remember to check the pH, and then perform several physical tasks before the results of the test are known. Additionally, the user must handle chemicals that are harmful and/or corrosive, with the added potential to stain various fabrics due to the dye nature of the testing compounds.
Another method commonly used to test the pH of a water sample involves use of indicator dyes deposited on test strips. According to these methods, a test strip is dipped into the water sample, allowing a color to develop. The color of the developed test strip is then compared to reference colors corresponding to known pH values, allowing identification of the pH of the water sample. This method is gaining popularity due to the convenience factor, but is limited due to an increased expense relative to the solution based methods. The test strips are not reusable or reversible, and the user must discard the test strip after using the product, thereby adding to the cost of this method. In addition, test strips rapidly degrade when left in aqueous solution and are not suitable for continuous monitoring of water chemistry.
Unfortunately, a product has not yet been described that allows continuous monitoring of an aquatic environment, is inexpensive and accurate, and is suitable for continuous pH monitoring and reuse in multiple applications. Thus, a need exists for reusable devices and methods for continuously monitoring the pH of an aquatic environment that are inexpensive and accurate, and that remove the requirement of the user to physically perform multiple mixing and measuring steps.

Reusable pH sensor device and related methods