A packaging structure and method for a light emitting diode is provided. The present invention uses flip-chip and eutectic bonding technology to attach a LED to a thermal and electrical conducting substrate. The flip-chip packaging structure comprises a thermal and electrical conducting substrate having an insulating layer formed in an appropriate area on the top surface of the substrate and a bonding pad formed on top of the insulating layer; and a LED reversed in a flip-chip style and joined to the substrate by eutectic bonding. A first electrode of the LED is eutectically bonded to an appropriate area on the top surface of the substrate via a eutectic layer, while a second electrode of the LED is electrically connected to the bonding pad.

1. Field of the Invention
The present invention generally relates to packaging structures for light emitting diodes, and more particularly to a flip-chip packaging structure and a related method for light emitting diodes with enhanced heat dissipating efficiency.
2. The Prior Arts
Light emitting diodes (LEDs) have advantages of small size, low power consumption, long operation life, and therefore will substitute light bulbs or fluorescent lamps in the future as the mainstream light source. However, to enhance the brightness of LEDs, it is necessary to increase power, numbers, or density of LEDs. These will inevitably increase the heat produced by the LEDs. This heat, if not effectively dissipated, will damage the LEDs themselves, shorten their operation life, and affect their brightness.
To improve heat dissipation, a packaging structure as shown in FIG. 1 has been adopted. As illustrated, LED 10 is attached to an aluminum substrate 20 by eutectic bonding with a eutectic layer 30 interposed therebetween. An insulating layer 21 is formed in specific areas on top of the aluminum substrate 20. Bonding pads 22 are in turn formed on top of the insulating layer 21, which are electrically connected to the first and second electrodes 11 and 12 of the LED 10 respectively via bonding wires 23. In this conventional approach, even though the eutectic layer 30 is able to dissipate the heat produced by the LED 10 through the aluminum substrate 20 by conduction, the sapphire substrate 13 of the LED 10 has inferior thermal conductivity and the heat dissipation efficiency is therefore impaired. Furthermore, the packaging structure described above has the first electrode 11 and the second electrode 12 both formed on the top of LED 10 which blocks light emitted from LED 10 and decreases its brightness.
To overcome the foregoing problems, a flip-chip packaging structure as shown in FIG. 2 is adopted, where LED 10 is reversed and attached to a printed circuit board (PCB) 40. The PCB 40 has bonding pads 41 formed on specific locations on the top surface, and the bonding pads 41 are electrically connected to bonding wires 42. The first and second electrodes 11 and 12 of the LED 10 are connected separately to bonding pads 41 using metallic bumps 43. Although the packaging structure indeed avoid blocking light emitted from LED, heat generated by the LED 10 can only be conducted to the PCB 40 through the small contact area with the metallic bumps 43. Additionally, the PCB 40 itself has limited thermal conductivity and cannot provide satisfactory help to the heat dissipation.

Flip-chip packaging structure for light emitting diode and method thereof


An IP based voice/video communication system and call pickup/forwarding method and a program storage device, readable by a machine, tangibly embodying a program of instructions executable by the machine to perform the call pickup/forwarding method enables a subscriber can have voice/video communication irrespective of time or place by forwarding voice/video calls between voice/video communication terminals such as a TV, PDA and home pad, or by picking up a incoming call at a nearby terminal if it is difficult for the subscriber to answer the call at the originally called terminal from his/her location.

1. Field of the Invention
The present invention relates to an Internet Protocol (IP) based voice/video communication system and a call pickup/forwarding method. More particularly, the present invention relates to an IP based voice/video communication system and a call pickup/forwarding method by which a voice/video incoming call received in a first terminal can be picked up by a second terminal and/or a call forwarding mode of the incoming call can be set to automatically forward an incoming call received in the first terminal to second terminal. In addition, the present invention also relates to a program storage device, readable by a machine, tangibly embodying a program of instructions executable by the machine to perform the call pickup/forwarding method.
2. Description of the Related Art
In general, Internet-phone services are used to provide voice communication by using a worldwide communication infrastructure, that is, the Internet instead of a conventional Public Switched Telephone Network (PSTN). The conventional PSTN as a circuit switching network performs static switching while providing a fixed bandwidth of 64 Kbps to guarantee communication quality. However, the Internet, as a packet switching network, performs dynamic routing to provide best-effort services, thereby rarely guaranteeing communication quality. Nevertheless, Internet phones are getting more widely used since they can provide inexpensive long distance calls as well as create various forms of services.
The Internet-phone services can be classified into PC-to-PC, PC-to-Phone, Phone-to-PC and Phone-to-Phone services. In the PC-to-PC service, two users who want to communicate with each other use their multimedia computers as Internet-phone terminals. The computers can be connected to each other on a Local Area Network (LAN), or connected to telephone lines via modems to use the Internet via an Internet Service Provider (ISP). A voice signal is sampled, compressed and packeted in a codec with software of a transmitting PC, and a received voice signal is regenerated by a sound card in a receiving PC.
In the PC-to-Phone service, a PC is first connected to an Internet-phone gateway and then a telephone number of a counterpart to call is inputted to the gateway so that the gateway interprets it to connect the PC to a counterpart telephone via a conventional PSTN.
In the Phone-to-PC service, a subscriber of a conventional PSTN connects to an Internet-phone gateway and provides the information of a counterpart to call so that the Internet-phone gateway allows the subscriber to communicate with a corresponding PC via the Internet.
The Phone-to-Phone service allows communication between conventional telephones via the Internet. In the Phone-to-Phone service, a user connects to a nearby gateway using a public telephone connected to a PSTN, and then inputs a counterpart telephone number after user authentication and caller identification for charge. Then, a calling gateway packets the counterpart telephone number and sends it to a gateway nearest to a receiving part. The receiving part gateway converts the packet into the telephone number again to call the counterpart via the PSTN. Upon establishment of the connection setup between the two users, voice data is coded in a gateway and transmitted via the Internet, and a counterpart gateway decodes the coded voice data into a voice signal that is sent to the counterpart via the PSTN.
Further, the IP-based voice/video telephone is being developing in various forms in both the office and home automation environment. In particular, the recent office and home environment mainly utilizes a private system using an Access Point (AP) such as a wireless LAN communication arrangement, which allows voice/video communication to be performed via a personal terminal, (for example, a PDA, a digital TV and a home pad).
However, because the voice/video communication can be performed only between a calling terminal and a receiving terminal, there is a problem in that mobility is not guaranteed but rather depends upon the position of the receiving terminal, in particular, when the receiving terminal is located in a home.
For example, if a call signal is received in a terminal in a bedroom when a subscriber is working in a living room, the subscriber must go to the bedroom to answer the call with a corresponding voice/video terminal (for example, a TV). When the subscriber wants to perform communication via a home pad on a refrigerator in the kitchen instead of the TV during communication, because call forwarding is not enabled, the subscriber must continue conversation via the TV or asks a caller to call again to the refrigerator home pad. This can be an annoyance or inconvenience to the user.
Furthermore, because the subscriber cannot pick up a incoming call with a terminal at hand to answer the call if the call is received by a remotely located terminal, there is a problem in that the mobility of the subscriber is not guaranteed.
The following patents each discloses features in common with the present invention but do not teach or suggest the inventive features specifically recited in the present application: U.S. Patent Application No. 2004/0028205 to Lim et al., entitled METHOD FOR PERFORMING EXTERNAL CALL FORWARDING BETWEEN INTERNET AND TELEPHONE NETWORK IN WEB-PHONE SYSTEM, published on Feb. 12, 2004; U.S. Patent Application No. 2003/0108176 to Kung et al., entitled PERSONAL IP FOLLOW-ME SERVICE, published on Jun. 12, 2003; U.S. Patent Application No. 2003/0210776 to Sollee et al., entitled METHOD AND APPARATUS FOR PROVIDING ADVANCED IP TELEPHONY SERVICES IN AN INTELLIGENT ENDPOINT, published on Nov. 13, 2003; U.S. Patent Application No. 2004/0008621 to Yaker, entitled SYSTEM AND METHOD FOR PROVIDING ADVANCED CALLING FEATURES TO A PACKET NETWORK-BASED COMMUNICATION DEVICE AND PACKET NETWORK EMPLOYING THE SAME, published on Jan. 15, 2004; U.S. Patent Application No. 2004/0017803 to Lim et al., entitled CALL FORWARDING METHOD, published on Jan. 29, 2004; U.S. Patent Application No. 2004/0028205 to Lim et al., entitled METHOD FOR PERFORMING EXTERNAL CALL FORWARDING BETWEEN INTERNET AND TELEPHONE NETWORK IN WEB-PHONE SYSTEM, published on Feb. 12, 2004; U.S. Patent Application No. 2004/0037272 to Park, entitled METHOD OF FORWARDING PACKET CALLS IN MOBILE COMMUNICATION SYSTEM, published on Feb. 26, 2004; U.S. Patent Application No. 2004/0042607 to Gallant et al., entitled METHOD OF AND SYSTEM FOR PROVIDING INTELLIGENT NETWORK CONTROL SERVICES IN IP TELEPHONY, published on Mar. 4, 2004; and U.S. Patent Application No. 2004/0076140 to Begeja et al., entitled METHOD AND SYSTEM FOR REMOTE CALL FORWARDING OF TELEPHONE CALLS FROM AN IP CONNECTION, published on Apr. 22, 2004.

IP-based voice/video communication system and call pickup/forwarding method


A method and apparatus for locating the boundary of an object. An electronic image of the object is formed, having a plurality of image pixels. Groups of the image pixels are identified that represent edge segments of the object. Patches are formed around the image pixel groups, where each patch is dimensioned and positioned to entirely contain one of the image pixel groups. A patch merge process is preformed that merges any two of the patches together that overlap each other by a predetermined amount, to form a merged patch that is dimensioned and positioned to entirely contain the two merged patches. The merge process continues for any overlapping patches and merged patches until none of the patches and the merged patches overlap each other by the predetermined amount. All the edge segments contained within one of the merged patches are associated as representing the boundary of the object.

Methods and systems for analyzing particles in a dilute fluid sample are well known, as disclosed in U.S. Pat. Nos. 4,338,024 and 4,393,466. Existing flow microscope particle analyzers use an image acquisition device and software that detects particles based on their brightness difference with the background. U.S. Pat. Nos. 4,538,299 and 5,625,709 are examples of such analyzers. Unfortunately, currently employed systems and methods often cannot efficiently detect low contrast particles, and often identify different parts of the same object as different objects, resulting in incorrect classification and reported element quantity.

Particle extraction for automatic flow microscope


A method to enhance grain size in polysilicon films while avoiding formation of hemispherical grains (HSG) is disclosed. The method begins by depositing a first amorphous silicon film, then depositing silicon nuclei, which will act as nucleation sites, on the amorphous film. After deposition of silicon nuclei, crystallization, and specifically HSG, is prevented by lowering temperature and/or raising pressure. Next a second amorphous silicon layer is deposited over the first layer and the nuclei. Finally an anneal is performed to induce crystallization from the embedded nuclei. Thus grains are formed from the silicon bulk, rather than from the surface, HSG is avoided, and a smooth polysilicon film with enhanced grain size is produced.

The invention relates to a method to enhance grain size in polycrystalline silicon, called polysilicon. Larger grain size in polysilicon is advantageous for many uses, particularly in thin film transistors (TFTs).
One of the major obstacles to the use of polysilicon thin film as a semiconductor in active devices is the relatively small grain sizes (around 0.05 micron or less) of polysilicon thin films deposited by such methods as low-pressure chemical vapor deposition and sputtering. A film with small grain size has a larger number of grain boundaries, decreasing carrier mobility. Typical electron mobilities in polysilicon films made using these methods are on the order of 10 cm2/volt-second, two orders of magnitude lower than electron mobilities in bulk silicon.
The poor electrical performance caused by grain boundaries in the channel region limits the use of TFTs largely to low-temperature flat panel displays. It is believed that electrical properties of TFTs can be improved if the grain size is enhanced and the number of grain boundaries in the channel region minimized.
There is a need, therefore, to enhance grain size in polysilicon thin films.

Large grain size polysilicon films formed by nuclei-induced solid phase crystallization


A charge control unit controls electricity charged to a piezo element, which is for actuating a backpressure control valve so as to control backpressure applied to a valve element for a fuel injection valve. The backpressure control valve is configured to start to decrease the backpressure to actuate the valve element to open an injection port of the fuel injection valve when voltage of the electricity exceeds a threshold. A charge unit increases the voltage by repeating increasing and decreasing a drive current, which is supplied to the piezo element, for multiple times for charging the piezo element. A switching unit alternates the increasing and the decreasing such that the voltage exceeds the threshold in an intermediate period in a middle of a specific increasing period among multiple increasing periods, in each of which the drive current increases.

According to JP-A-2006-144588, a fuel injection valve includes a valve element for opening and closing a fuel injection port, a backpressure control valve for controlling backpressure of the valve element, and piezo elements for actuating the backpressure control valve. When the piezo elements are charged so as to expand, the piezo elements actuate the backpressure control valve to reduce backpressure of the valve element, and thereby the valve element performs an opening operation, and fuel is injected from the injection port.
In JP-A-2006-144588, after charge of the piezo elements is started, the backpressure control valve starts operation at the time point when a voltage value of charged power exceeds a threshold value Vth (refer to FIG. 5B). Conventionally, a charge control unit for controlling electric charge of the piezo elements is typically designed such that while a drive current to be supplied to the piezo elements is repeatedly increased and decreased for several times (refer to FIG. 5A), a voltage value is increased (refer to FIG. 5B) so that the piezo elements are charged.
Here, for example, even when the amount of electric charge of the piezo elements is fixed, the piezo elements may differently expand depending on temperature in each charge operation. Moreover, because of aged deterioration such as ablation of a valve seat for the valve element or the backpressure control valve, even when the amount of electric charge of the piezo elements is fixed, the piezo elements may differently expand depending on ablation in each charge operation. That is, variation may occur in timing, at which the backpressure control valve starts operation, due to the aged deterioration or a temperature characteristic of each piezo element. Thus, variation may occur in valve opening operation timing (injection start timing) of the valve element.

Charge control unit and charge control system for fuel injection valve


A color cathode ray tube includes: a panel whose outer surface is substantially flat and whose inner surface has a predetermined curvature; a funnel coupled with the panel; and a deflection yoke installed on an outer circumference of the funnel, wherein the panel has an aspect ratio of about 4:3 and a diagonal length USD of a viewable image size of the panel is less than about 520 mm. The panel satisfies the following relationship:

1. Field of the Invention
The present invention relates to a flat color panel cathode ray tube (CRT), and more particularly, to a panel structure and a funnel structure of a flat color panel cathode ray tube (CRT).
2. Description of the Related Art
FIG. 1 is a partial side sectional view illustrating a general color cathode ray tube. Referring to FIG. 1, the general color cathode ray tube will be described.
The CRT includes a front panel 1 and a rear funnel 2. The panel 1 and the funnel 2 are all made of glass, and the rear funnel 2 is coupled with a rear side of the front panel 1. A fluorescent material coats the inner surface of the panel 1 to form a fluorescent surface. The fluorescent surface emits light when struck by an electron beam 11. An electron gun 8 generates the electron beam 11 and is located in a neck 10 of the funnel 2. A shadow mask 3 serves to selectively pass the electron beam 11 so that the electron beam 11 reaches a desired position of the fluorescent surface. This shadow mask 3 is supported by a frame 4 and located in the vicinity of the inner surface of the panel 1. The frame 4 is fixed to the panel 1 by a spring 5 and a pin 6. A deflection yoke 9 is installed on an outer circumference of the funnel 2. The deflection yoke 9 sequentially deflects the electron beam 11 up, down, left, and right. The fluorescent surface struck by the electron beam 11 forms a picture. An inner shield 7 is fixed to the frame 7 so that the travel of the electron 11 is not affected by any external earth magnetic field. Because the inside of the CRT is in a high vacuum state, the CRT is vulnerable to external impact. Accordingly, the panel 1 and the funnel 2 are designed to have enough strength to counter such a vacuum pressure. A reinforcing band 12 is installed on the outer surface of the skirt of the panel 1, and thus the stress that the CRT is subject to under a high vacuum is dispersed.
A CRT is an image display device and has been the most popular display device in various fields. Recently, the CRT has been improved due to technology improvements and customers' requests. Especially the flat panel CRT has been developed to minimize image distortion.
Referring to FIG. 2A, the conventional panel includes an inner surface and an outer surface that have a predetermined curvature. Accordingly, an image is distorted and ambient light is reflected in many directions due to the curvature of the outer surface resulting in degraded viewing capability. To improve the conventional panel, as shown in FIG. 2B, a flat panel that has a substantially flat outer surface has been developed. The flat panel removes the image distortion and lowers eye fatigue, so it has gained widespread use recently.
A more detailed description of the difference between the curved panel and the flat panel will be made with reference to FIG. 3. The half cross-sectional surface of the curved panel is depicted on the right side of FIG. 3 and the half cross-sectional surface of the flat panel is depicted on the left side of FIG. 3.
Typically, the curved panel and the flat panel are manufactured on the same manufacturing line. The curved panel is employed in less expensive CRTs and the flat panel is employed in more expensive CRTs. For convenience, the CRT that has the flat panel is called a 'flat panel CRT' and the CRT that has the curved panel is called a 'curved panel CRT'. Accordingly, to enhance the efficiency of the manufacturing processes, as shown in FIG. 3, the flat panel CRT is designed to have the same panel height as the panel height (OAH: the height distance between the center of the outer surface and the seal edge line of a skirt 1 a coupled with the panel 2) of the curved CRT.
However, due to such a design as shown in drawings, the length of the skirt 1a of the flat panel gets longer. Because the outer surface of the panel 1 is flat but the inner surface of the panel 1 has a curvature, the corner portion 1b gets thicker as compared to the curved panel. Accordingly, the flat panel 1 is heavier than the curved panel 2 by about 10–15%, so that the assembly process for the flat panel CRT becomes more difficult, and its use becomes inconvenient. Also, the flat panel 1 is vulnerable to excess thermal stress in a furnace as the volume and weight increases.

Lightweight flat screen color cathode ray tube

Abstract: 0.44  ≤      OAH    TOR    ≤  0.56where TOR is distance between an end of the deflection yoke adjacent to the panel and a coupling surface between the panel and the funnel, and where OAH is distance between center of the outer surface of the panel and the coupling surface between the panel and the funnel.


This invention relates to wettable biomedical devices comprising amphiphilic block copolymers. The amphiphilic block copolymers are useful as internal wetting agents for biomedical applications, such as implantable devices, ophthalmic devices and in one embodiment, contact lenses.

Contact lenses have been used commercially for vision improvement since at least the 1950s. The first contact lenses were made of hard materials and as such were somewhat uncomfortable to users. Modern lenses have been developed that are made of softer materials, typically hydrogels and particularly silicone hydrogels. Silicone hydrogels are water-swollen polymer networks that have high oxygen permeability and surfaces that can be more hydrophobic than hydrophilic.
Others have tried to make silicone hydrogel contact lenses more hydrophilic by applying hydrophilic coatings thereto. For example, it has been disclosed that silicone hydrogel lenses can he made more compatible with ocular surfaces by applying plasma coatings to the lens, and treating the lenses with reactive hydrophilic polymers.
Incorporation of internal hydrophilic wetting agents such as PVP and poly-2-ethyl-2-oxazoline, and polymerizable surfactants into a silicone hydrogel reaction mixture has been disclosed.
High molecular weight hydrophilic polymers have been used as internal wetting agents (IWA) in silicone hydrogel lenses, however, such polymers may be difficult to solubilize in reaction mixtures that contain silicones. In order to solubilize these wetting agents, compatibilizing components must be used. These compatibilizing components must be prepared in a separate step and then subsequently mixed with the remaining ingredients of the silicone hydrogel formulation. This additional step (or steps) increases the cost and the time it takes to produce these lenses.
Therefore it would be advantageous to find a lens formulation that does not require the use of surface treatment to provide eye wettability and resistance to surface depositions.

Biomedical devices containing amphiphilic block copolymers


A method and system for maintaining a self-updating security information repository. A plurality of types of security information are stored in a corresponding plurality of information storage units, such as database tables. A plurality of configuration files respectively associated with the information storage units are stored, and each configuration file includes update parameters of the associated information storage unit. Each information storage unit is periodically automatically updated based on its update parameters. The information storage units can be searched to return security information of different types in one search.

The present invention is generally directed to storing network security information. More specifically, the present invention is directed to a system and method for storing different types of security information in an automated centralized security information repository.
When a network security issue arises, such as abnormal traffic in a data network, a network analyst is responsible for determining the cause of the security issue. Abnormal traffic is traffic that is not normally observed, such as sudden volume changes or unusual tcp/ip indicators. For example, abnormal traffic in a data network can be caused by viruses, worms, denial of service attacks, hackers probing a system, attempted break-ins, games, etc. In order to determine the cause of a security issue, an analyst must manually search security information sources, such as IANA port listings, IANA protocol listings, virus information listings, Trojan horse information listings, network game developers' game information, hacker web sites, search engines, newsgroups, etc. Furthermore, in order to obtain different types of security information (e.g., virus information, common port usage information, etc.), an analyst must search separate data repositories corresponding to each desired type of information. For example, an analyst interested in activity on a certain port will have to search one source for information on applications that commonly use the port, another source for virus information relating to the port, another source for games that use that port, etc. Accordingly, it is desirable to increase efficiency in security information searches.

Security information repository system and method thereof


A system for encapsulating configuration information in storage objects formatted for backup and restore comprises a processor coupled to a memory, where the memory stores instructions executable by the processor to implement a backup manager configured to generate backup versions of a plurality of storage objects (such as files or directories) of a source data set of a primary host. The backup manager may be configured to create an additional storage object that includes information collected from a designated information source in a first format, store the additional storage object within the source data set in a second format, and generate a backup version of the additional storage object.

1. Field of the Invention
This invention relates to computer systems and, more particularly, to backup and restoration of data within computer systems.
2. Description of the Related Art
Many business organizations and governmental entities rely upon applications that access large amounts of data, often exceeding many terabytes of data, for mission-critical applications. Numerous different types of storage devices, potentially from multiple storage vendors, with varying functionality, performance and availability characteristics, may be employed in such environments.
Any one of a variety of factors, such as system crashes, hardware storage device failures, software defects, or user errors (e.g., an inadvertent deletion of a file) may potentially lead to data corruption or to a loss of critical data in such environments. In order to recover from such failures, various kinds of backup techniques may be employed. For example, in some storage environments, file-level replication may be employed, where a complete copy of the set of files in one or more file systems at a primary host may be created at a secondary host. If the primary host fails, or if the file system at the primary host becomes corrupted or unavailable, the files may be recovered or restored by copying from the replica.
However, simply restoring contents of storage objects such as files or directories may be insufficient for a desired level of recovery from certain types of failures. For example, if a primary host whose files are backed up by a file replication mechanism fails, users may desire that the configuration state of the primary host also be restored, along with the file data. Unfortunately, some types of system configuration information, as well as other information appropriate for backup such as application-generated or user-supplied information, may not typically be available or stored in a format recognized by the replication mechanism, and as a result, may not typically be backed up along with the storage object data. For example, in storage environments employing file-based replication as the backup mechanism, configuration information related to network-based file shares may not be stored in a file format accessible to the file replication engine, and various elements of system state information may also be stored in data structures other than files, or may have to be collected from portions of several files. Requiring separate backup mechanisms to be implemented for different sources of configuration information and any other non-file structured information that may be needed for restoration may not be a cost-effective solution in many storage environments. In addition, in some storage environments, especially environments where disk-based backups are implemented, transparent access to some or all of the backup versions of storage objects may be provided to end users. That is, end users may be permitted to access backup versions of storage objects directly, without administrative intervention. In such environments, when accessing the backup versions, some end users may expect to make use of configuration settings (such as file share settings) similar to those of the primary host.

Encapsulating information in a storage format suitable for backup and restore


A contact charging device, in which a contact member for charging has a surface including a contact portion to be in contact with a charge receiving member as well as a charge contributing portion having a surface resistivity (.rho.s) of 1.times.10.sup.5 .OMEGA./.quadrature. or less. A maximum distance between the contributing portion and the charge receiving member is in a range from 5 .mu.m to 60 .mu.m. Alternatively, an electric power formed of a DC component is applied to the contact member to produce a potential difference in a range from 550 v to 750 v between the applied power and a potential at the surface of the charge receiving member before being charged by the electric power.

1. Field of the Invention
The present invention relates to a charging method and a charging device for charging a charge receiving member. In particular, the invention relates to a charging method and a charging device for charging a charge receiving member through a portion in contact with the charge receiving member. More specifically, the invention relates to a charging method and a charging device having a member to be in contact with an electrostatic latent image carrier such as a photosensitive member in an image forming apparatus for charging the electrostatic latent image carrier to a predetermined potential.
2. Description of the Related Art
In electrophotographic image forming apparatuses such as a copying machine and a printer, a charging device charges an electrostatic latent image carrier such as a photosensitive drum, image exposure is effected on a charged area to form an electrostatic latent image, the electrostatic latent image is developed into a visible image, and this visible image is transferred and fixed onto a transfer member. A charging device is employed for charging the surface of the electrostatic latent image carrier prior to formation of the latent image. The apparatus also employs other charging devices such as a transfer charger for transferring the visible image formed on the electrostatic latent image carrier onto a transfer member and a separating charger for separating the transfer member bearing the transferred visible image from the electrostatic latent image carrier.
As the charging devices, corona charging devices such as a Corotron charging device or a Scorotron charging device utilizing corona discharging have been used. Although the corona charging device can advantageously perform stable charging, it requires a high voltage and produces a large amount of ozone. In recent years, therefore, contact charging devices which can replace the corona charging devices have been proposed.
The contact charging device has a charging member which is subjected to a voltage and is brought into contact with a charge receiving member. The charge receiving member is charged by discharge occurring at a gap between a region, which is continuous to a contact region of the charging member with the charge receiving member and is spaced from the charge receiving member, and the surface of the charge receiving member.
The charging member may take various forms such as a charging roller and a charging brush, and other forms such as a charging blade and a charging film have been proposed.
These contact charging devices have such an advantage that they produce a particularly smaller amount of ozone than the corona charging device. Also, the contact charging device can operate with a voltage lower than that required by the corona charging device.
However, the contact charging device may suffer from the following problem. If the charging member is made of a material of a low resistance such as metal, the surface of the charge receiving member is irregularly charged into a scale-like form (scaly form). Therefore, if the charge receiving member is an electrostatic latent image carrier and a mesh image of 1-dot/4-dots is formed as shown in FIG. 4, irregularity in image density occurs in the mesh image due to lack and/or drop of dots forming mesh points. This results in scale-like noises as shown in FIG. 9. This means that the surface of the charge receiving member was not uniformly charged, and charging irregularity occurred in a scale-like form. This problem does not occur if the charging member is made of a material of a high resistance. Therefore, it has been impossible to employ the charging member of a low resistance such as metal, and it has been required to employ the charging member made of a material of a high resistance such as rubber or resin containing an electrically conductive material dispersed therein.
Charging irregularity in a striped form may occur at the surface of the charge receiving member when a scratch is formed at a portion of the charging member in contact with the charge receiving member and the scratch is stuffed with a foreign material such as toner. For suppressing this, the charging member may be made of a hard material. Such a hard material may be metal. However, metal cannot be employed due to the aforementioned reason. Therefore, it is necessary to employ a charging member made of a material which is formed of specific hard resin and a conductive material such as electrically conductive carbon dispersed therein. The same is true with respect to the case where a charging member having a sufficient resistance against wear is employed.
For the reasons described above, a material of the charging member can be selected only from a limited range.


A method that includes (a) thermally biasing an electro-optic polymer device using an electrode; and (b) driving the electro-optic polymer device by applying a high frequency signal to the device using the same electrode.

All patents, patent applications, and publications cited within this application are incorporated herein by reference to the same extent as if each individual patent, patent application or publication was specifically and individually incorporated by reference.
The invention relates generally to active optical waveguide devices. Electro-optic polymer waveguide devices are attractive candidates for optical communication devices that operate at high speed and low electrical power. In addition, the good speed match between the optical and microwave signals enables high bandwidth operation. Some optical communication devices, such as Mach-Zehnder modulators, operate at microwave (RF) frequencies using a separate DC electrical bias, which usually requires a separate electrode in addition to the microwave electrode. DC bias drift is a critical factor for long-term performance of commercially viable modulators. EO polymer modulators generally have a large amount of DC bias drift, and this has been addressed using thermal biasing techniques, for example see: S. Park, et al. Appl. Phys. Lett. 83, 827-829 (2003). This technique requires a separate "heater" electrode, which decreases the active length of the microwave electrode or hinders push-pull operation, thereby causing the driving voltage to increase. The heater electrode is also thicker than the microwave electrode, or is fabricated from a different metal altogether, which increases the number of fabrication steps and device costs. Thus, electro-optic polymer modulators need new device structures or new methods that bias the modulator without causing a decrease in the active length of the microwave electrode.

Method of biasing and operating electro-optic polymer optical modulators


According to the present invention, a method and apparatus for generating power aboard a marine vessel is provided. The method comprises the steps of: (a) providing a Rankine Cycle device that includes at least one of each of an evaporator, a turbo-generator that includes a turbine coupled with an electrical generator, a condenser, and a refrigerant feed pump; (b) disposing the one or more evaporators within an exhaust duct of a power plant of the marine vessel; (c) operating the power plant; and (d) selectively pumping refrigerant through the Rankine Cycle device, wherein refrigerant exiting the evaporator powers the turbine, which in turn powers the generator to produce power.

1. Technical Field
The present invention relates to methods and apparatus for infrared suppression in general, and to methods and apparatus for decreasing the exhaust temperature of a marine vessel power plant in particular.
2. Background Information
Marine power plants produce exhaust products typically in a temperature range of 350–1800° F. In most applications, the exhaust products are passed through a sizable duct (typically referred to as a "stack") and released to the environment. Once released to the environment, the thermal energy dissipates. A problem with releasing thermal energy directly to the environment is that the marine vessel emits a substantial, undesirable thermal signal.
What is needed is a method and apparatus for suppressing the thermal signal of a marine vessel.

Method and apparatus for decreasing marine vessel power plant exhaust temperature


A logic circuit is formed of an I.sup.2 L cell structure in which a difference of switching speeds at every collector in a multi-collector structure is small. In a semiconductor device in which an integrated injection logic cell including a constant current source transistor and a switch transistor is formed on a common semiconductor substrate, a first semiconductor layer (13) doped with a first conductivity type impurity and a second semiconductor layer (19) doped with a second conductivity impurity are electrically isolated from each other on a semiconductor substrate. A plurality of collector electrodes of the switch transistor and a plurality of collector regions (20) based on diffusion of impurity are formed by the second semiconductor layer (19). The first semiconductor layer (13) includes a base electrode deriving portion, and a direct contact portion which directly contacts with the semiconductor substrate between a plurality of collector regions (20). An external base region (17) is formed by diffusion of first conductivity type impurity from the direct contact portion.

The present invention relates to a semiconductor device having an integrated injection logic (IIL) cell structure, and a method of fabricating the same.
The integrated injection logic, which is often referred to as "I.sup.2 L", cell comprises a common semiconductor substrate, a constant current source transistor, and a switch transistor, both of the constant current source transistor and the switch transistor being formed on the above common semiconductor substrate. The most specific feature of the I.sup.2 L cell lies in that a logic circuit can be easily incorporated therein with high density by the same processing as that of bipolar transistors. The I.sup.2 L cells have been widely used before CMOS (complementary MOS insulating gate field-effect transistor integrated circuit) became widespread.
At present, as the circuit element is made large-scale, high-speed, low in power consumption, and inexpensive much more by microminiaturization based on CMOS, it is frequently observed that CMOS plays a leading part in forming logic circuits.
On the other hand, the I.sup.2 L cell structure makes it possible to make a linear circuit in the form of semiconductor chip. In a small or middle scale manufacturing process, the I.sup.2 L cell structure is inexpensive, and hence used in commercial sector.
Logic circuits based on the I.sup.2 L cell structure also can be made large-scale, high-speed, low in power consumption, and inexpensive by microminiaturization of circuit element similarly to the CMOS.
In the I.sup.2 L cell structure, as a means for realizing the microminiaturization of circuit element, it is considered that structure and manufacturing method of emitter/base self-align structure bipolar transistor based on upper and lower two layers of polycrystalline silicon are applied to the I.sup.2 L cell structure (see T.H. Ning, Symp. of VLSITECH, Invited Paper, Page 34 (1981)).
The logic circuit based on the I.sup.2 L cell structure includes a multi-collector structure composed of a plurality of collector regions and collector electrodes formed within the unit cell. However, in this I.sup.2 L cell, switching speeds are different at every collectors composing the multi-collector structure. As a consequence, a designing of circuit becomes difficult, and such logic circuit has not yet been made large-scale.
As a cause that the switching speeds become different at every collectors in the above multi-collector structure, there is enumerated the following one. That is, a base series resistance R.sub.B is increased as the position of the collector becomes distant from the base, and a current amplification factor and a cutoff frequency at a switching transistor (bipolar transistor in the reverse direction) provided within the I.sup.2 L cell structure are lowered when a potential drop occurs at that portion, resulting in the switching speed being lowered.
FIG. 1A is a plan view of a unit cell of conventional I.sup.2 L cell structure, and FIG. 1B is a cross-sectional view thereof.
In this example, as illustrated in FIGS. 1A and 1B, on an n-type emitter region 60 surrounded by an emitter electrode deriving region 60a heavily doped with n-type impurity, there are formed a base region 61 composed of a p-type intrinsic base region 61s and an external base region 61g heavily doped with p-type impurity, and an injector region 62 heavily doped with p-type impurity. A plurality of collector regions 63 heavily doped with n-type impurity are formed on the intrinsic base region 61s.
An emitter electrode E, a base electrode B, an injector electrode I, and collector electrodes C (collector electrodes C1 through C5) are respectively formed on respective regions of the emitter electrode deriving region 60a, the external base region 61g, the injector region 62, and the collector region 63 to make an ohmic contact.
Of the above-mentioned regions, the intrinsic base region 61a, and the external base region 61g are formed by implanting ions of low impurity concentration and high impurity concentration through masks.
FIG. 2 is a graph showing a relationship between an injection current of an I.sup.2 L ring type oscillator and a delay time in the I.sup.2 L cell structure shown in FIGS. 1A and 1B while an ion injection dose of the external base region 61g is taken as a parameter. In the I.sup.2 L ring type oscillator, unit cells of odd number are selected. In each unit cell, a base electrode and a collector electrode are connected in series to a base electrode or a collector electrode of adjacent unit cell, and an output of a final gate (base electrode or collector electrode) is oscillated as an input of the first gate, thereby measuring an oscillation frequency and a switching delay time.
A base electrode of adjacent cell and one collector electrode in a plurality of collector electrodes are sequentially connected by Al wire or the like.
Specifically, assuming that B.sub.1, B.sub.2, B.sub.3, . . . B.sub.n are base electrodes of 1, 2, 3 . . . , nth (n is an odd number) unit cells, and that C.sub.1, C.sub.2, C.sub.3, . . . , C.sub.n are collector electrodes, then electrodes of the same kinds are connected in such a way as in B.sub.1 -B.sub.2, C.sub.2 -C.sub.3, B.sub.3 -B.sub.4, . . . , C.sub.n-1 -C.sub.n or electrodes of different kinds are connected in such a way as in B.sub.1 -C.sub.2, B.sub.2 -C.sub.3, B.sub.3 -C.sub.4, B.sub.4 -C.sub.3, . . . , B.sub.n-1 C.sub.n, and finally the electrodes B.sub.n -C.sub.1 are connected in a loop-fashion, thereby forming the ring type oscillator.
In FIG. 2, the vertical axis represents a delay time (ns), and the horizontal axis represents an injection current (.mu.A), each of which is represented by a logarithmic scale.
In FIG. 2, crosses show measured results obtained when a dose of ions implanted on the external base region 61g is 1.times.10.sup.14 cm.sup.-2 and a layer resistance is 500.OMEGA./.quadrature., and open circles show measured results obtained when a dose of ions implanted on the external base region 61g is 2.times.10.sup.14 cm.sup.-2 and the layer resistance is 315.OMEGA./.quadrature.. Open triangles show measured results obtained when the dose of ions implanted on the external base region 61g is 3.times.10.sup.14 cm.sup.-2, and the layer resistance is 230.OMEGA./.quadrature., and open squares show measured results obtained when the dose of ions implanted on the external base region 61g is 5.times.10.sup.14 cm.sup.-2 and the layer resistance is 150.OMEGA./.quadrature..
When the ring type oscillator comprises a base and a collector which are disposed most closely to each other, or when a base electrode and a collector electrode disposed adjacent to this base electrode in the unit cell are used in the ring type oscillator and these electrodes are disposed at the end of the opposite side of the injector (curve group A in FIG. 2), study of FIG. 2 reveals that a delay time has no dose dependence.
On the other hand, when the ring type oscillator comprises a base electrode and a collector electrode which are disposed most distant from each other, or when the base electrode adjoins the injector and the collector disposed at the end of opposite side of the injector and the base electrode in the unit cell is used in the ring type oscillator (curve group B in FIG. 2), study of FIG. 2 reveals that a delay time is reduced as the dose is increased, i.e., operation speed is increased in the large current side where the injector current is 10 .mu.A or higher.
In general, the I.sup.2 L cell is formed at the same time the bipolar transistor is formed on the same semiconductor substrate as other device.
Specifically, I.sup.2 L cells based on an emitter/base self-align bipolar transistor and a collector/base self-align switch transistor are simultaneously formed by first and second semiconductor layers of polycrystalline silicon. FIG. 3A is a plan view of such I.sup.2 L cell structure, and FIG. 3B is a cross-sectional view thereof.
In the unit cell of the I.sup.2 L cell structure shown in the plan view of FIG. 3A, an injector I, a base B, collectors C collectors C.sub.1 to C.sub.3) and an emitter E are formed from right in FIG. 3A, in that order.
In the cross-sectional view of FIG. 3B, an emitter buried region 32 heavily doped with impurity and an emitter buried region 33 lightly doped with impurity are formed on a p-type semiconductor substrate 31. An injector region 36, a base electrode deriving region 34 and a plurality of base regions 34g each of which is heavily doped with p-type impurity are formed on the emitter region 33, and a plurality of collector regions 35 heavily doped with n-type impurity are formed on the intrinsic base regions 34s, 34s lightly doped with p-type impurity between the respective external base regions 34g. These regions constitute the I.sup.2 L cell.
Emitter electrode deriving regions 38 are formed around the cell, and isolation insulating layers 37 are formed outside the emitter electrode deriving regions 38.
In actual practice, a plurality of I.sup.2 L cell are formed on the common semiconductor substrate 31 at the same time, and adjacent cells are overlapped at the positions shown by broken lines in FIG. 3A.
In the above I.sup.2 L cell, the base region 34 composed of the external base regions 34g and the intrinsic base regions 34s surrounded by the external base regions 34g are formed by the process below as shown in a cross-sectional view of FIG. 4.
Initially, an oxide insulating film 42 is formed on the surface of a semiconductor substrate, and openings are respectively formed through the insulating film 42 at its portions where a base region 34, a base electrode deriving region 34b, and an injector region 36 are formed. First semiconductor layers 41 made of polycrystalline silicon doped with p-type impurity are formed on the emitter region 33 through these openings.
Further, interlayer insulators 43 are formed over the whole surface of the first semiconductor layer 41, and openings are formed through the interlayer insulators 43 and the first semiconductor layers 41 formed under the interlayer insulators 43 at their portion where collector regions are formed. Through these openings, ions of p-type impurity are implanted on the intrinsic base region.
An insulating film 50 is formed over the whole surface by CVD (chemical vapor deposition).
Then, p-type impurities of high concentration are diffused from the first semiconductor layer 41 into the emitter region 33 by annealing, thereby forming the external base regions 34g, the base electrode deriving region 34b, and the injector region 36. Intrinsic base regions 34s are composed of the portions which are formed by implanting p type ions.
In this manner, as shown in the cross-sectional view of FIG. 4, there is formed the base region 34 composed of the intrinsic base region 34s and the external base region 34g.
Thereafter, side walls are formed in the openings of the above collector region forming portions by etching the insulating film 50 by RIE (reactive ion etching) as shown in FIG. 3B. Then, as shown in FIG. 3B, second semiconductor layers 44 of polycrystalline silicon doped with n-type impurity are formed on the intrinsic base regions 34s over the whole collector region forming region through these openings. Subsequently, collector regions 35 are formed by diffusing n-type impurities from the second semiconductor layers 44 by annealing.
Electrode contact openings are formed on the insulating films 42 and the interlayer insulators 43 on the emitter electrode deriving region 38, and electrode contact openings for exposing the first semiconductor layers 41 are formed on the interlayer insulators 43 on the base electrode deriving regions 34b and the injector regions 36. A metal layer such as an Al layer is deposited on the whole surface, and an emitter electrode 45e, a base electrode 45b, an injector electrode 45i, and a collector electrode 45c are respectively formed on the first semiconductor layer 41 on the base electrode deriving region 34b, the first semiconductor layer 41 on the injector region 36, and the second semiconductor layer 44 on each collector region 35 by patterning based on photolithography. The second semiconductor layer 44 is etched away except the collector electrode forming portion after the collector electrode 45c has been treated by patterning.
The base region 34 and the base electrode deriving region 34b are formed by the first semiconductor layer 41, and the positions of the base region 34 and the base electrode deriving region 34b are aligned by the first semiconductor layer 41. Further, the base electrode 45b formed on the base electrode deriving region 34b in ohmic contact is electrically connected to the base regions 34. The collector regions 35 and the base regions 34 are aligned by the second semiconductor layers 44, and the collector electrode deriving regions 34b are aligned with the collector regions 35 by the second semiconductor layers 44.
In the above arrangement, the base electrode 45b and the base regions 34 are electrically coupled by the first semiconductor layers 41 formed on the insulating layer 42, and hence a resistivity of the polycrystalline silicon layer doped with impurity is relatively large. As a consequence, a resistance of bases connected in series concerning the base region distant from the base electrode 45b, in particular, is increased.

Integrated injection logic semiconductor device


A percent body fat measuring apparatus includes a first and a second electrodes with which a living body is brought into contact, a detection resistor of which one terminal is connected to the second electrode, signal generator which produces a measurement signal and applies a produced measurement signal between the first electrode and the other terminal of the detection resistor, level detector for detecting the level of a signal which develops between the terminals of the detection resistor and is an object of detection, and percent body fat computer for determining percent body fat on the basis of a result of detection operation performed by the level detector. A measurement signal produced by the signal generator is made analogous to a half-wave waveform, and the level detector detects the level of a waveform analogous to a half-wave of the signal to be detected.

The invention relates to a percent body fat measuring apparatus for measuring percent body fat on the basis of bio-impedance, and more particularly, to a percent body fat measuring apparatus which measures bio-impedance by causing a signal analogous to a half-wave waveform to flow through a living body.
As described in, e.g., the Japanese Patent No. 2835656, the Unexamined Japanese Patent Application Publication Nos. Heill-104104, Heill-113872, and 2001-212098, according to related-art techniques for measuring bio-impedance, a sinusoidal waveform of 50 KHz or the like is used as a measurement signal to be caused to flow through a living body (hereinafter called a "measurement signal"). A voltage stemming from flow of the measurement signal through the living body is extracted through use of an electrode to be brought into contact with the living body. Next, after being amplified by a differential amplifier, the voltage is converted into a d.c. voltage through use of a rectifier circuit. A d.c. level of the voltage is read through use of an analog-to-digital converter (this technique is taken as a first "related-art").
Under the assumption that a circuit shown in FIG. 15 is used as the rectifier circuit, when a voltage of operating power is set to, e.g., four volts, a range of variation in the level of a rectified output assumes a value of about 1.5 volts, because of influence of a forward voltage of a diode which performs rectification. Specifically, this results in occurrence of a deficiency in the rectified output. With a view toward eliminating such a problem, a circuit shown in FIG. 13 is put forth. Specifically, a scan be seen from an input and an output of the circuit shown in the drawing, when an input varies from zero volts to two volts, an output varies from four volts to two volts. Accordingly, when the voltage of the operating power is set to four volts, the range of variation in the level of the rectified output can be set to two volts. Specifically, the circuit prevents narrowing of the range of variation in the level of the rectified output, which would otherwise be caused under the influence of the forward voltage of the diode which performs rectifying operation (this technique is taken as a second related-art technique).
Further, when bio-impedance is measured, a measurement signal, such as an a.c. signal, is caused to flow through a living body, and a voltage stemming from flow of the measurement signal through the living body is detected. However, the thus-detected voltage sustains the influence of an error of a value of the electric current flowing through the living body or the influence of an error arising in a detection circuit for detecting a voltage. A related-art technique for solving such an error is put forward in Japanese Patent No. 2835656. According to this technique, a plurality of groups of reference resistors are inserted in current paths which permit flow of the measurement signal into the living body. Voltage drop values corresponding to the respective reference resistors, which differ in resistance value from each other, and a voltage drop value corresponding to the living body are measured through use of a single circuit under the same measurement environment. From the values of the respective reference resistors and the voltage drop values corresponding to the respective reference resistors, a correlation between a voltage drop value and impedance is determined. The thus-determined correlation is applied to a voltage drop value of the living body, to thereby compute bio-impedance. The error of the value of the electric current flowing through the living body and the error arising in the detection circuit for detecting a voltage are eliminated. Consequently, the thus-measured bio-impedance assumes a highly accurate value (this technique is taken as a first related-art technique).
A configuration shown in FIG. 21 is also put forward, by the present applicant. More specifically, signal generator 503 for producing a measurement signal whose waveform is analogous to a half-wave waveform is provided, and a generated measurement signal is applied to a first electrode 501. A second electrode 502 is grounded by way of a detection resistor R514. The level of a half-wave of a half-wave signal developing between terminals of the detection resistor R514 is detected by use of level detector 504. The level detector 504 is configured from only discrete elements which are inexpensive (this technique is taken as a second related-art technique).
As is touched on in the description of the second related-art technique, the voltage of the operating power for an apparatus which displays percent body fat on the basis of measured bio-impedance (i.e., a percent body fat measuring apparatus) is set to a low voltage such as four volts. In order to facilitate transport of the apparatus, a battery is used as a power source. According to the first related-art technique, an amplitude of the measurement signal is limited to a value as low as four volts. In contrast, a signal detected from the living body is rectified after being amplified. Specifically, only a half-wave component of the sinusoidal wave becomes effective for measuring bio-impedance. Put another way, even when the operating power is set to four volts and when the amplitude of the measurement signal is also set to four volts, only a component corresponding to two volts is utilized as an effective component. As described in connection with the second related-art technique, a rectifier circuit formed from a complicated circuit configuration is required. Even when a rectifier circuit having such a complicated circuit configuration is used, the range of variation in the rectified output is limited to two volts. Therefore, when the level of a signal developing in the living body as a result of flow of the measurement signal through the living body is detected, difficulty is encountered in improving a detection accuracy.
Further, according to the second related-art technique, when a temperature rises, a base current of a p-n-p transistor Q501 also increases. Hence, an output level of the collector of the transistor rises in association with the temperature rise. A forward voltage of a diode D506 decreases in association with the temperature rise. Even when the level of the collector remains constant, a rectified output 651 is increased in response to the temperature rise. Consequently, as a whole, the temperature change induces occurrence of synergistic action between an increase in the base current of the p-n-p transistor Q501 and a decrease in the forward voltage of the diode D506, thereby deteriorating a temperature characteristic. According to the second related-art technique having such a characteristic, the level of the signal developing between the terminals of the detection resistor R514 directly indicates bio-impedance Z to be measured. Hence, the method for eliminating an error according to the first related-art technique cannot be applied to the second related-art technique. Therefore, demand arises for another method for enhancing accuracy of detection of the bio-impedance Z.

Percent body fat measuring apparatus using a half-wave waveform


A mixed mode chromatography method for separating correctly folded from incorrectly folded conformations of a given protein is provided. The method is highly effective in separating correctly folded etanercept from incorrectly folded etanercept and aggregates in commercially attractive yields capable of affording etanercept preparations having very high purity in terms of correctly folded etanercept versus incorrectly folded etanercept. The invention is further directed to protein preparations and formulations comprising correctly folded proteins obtained using the present methods, and methods of treatment using the high purity preparations obtained from the mixed mode method.

Etanercept (Enbrel®, manufactured by Immunex Corporation) is a dimeric fusion polypeptide consisting of the extracellular ligand-binding portion of the human 75 kilodalton (p75) tumor necrosis factor receptor ("TNFR") linked to the Fc receptor [fragment, crystallizable] region of human Immunoglobulin G ("IgG1"). Etanercept consists of 934 amino acids and has an apparent molecular weight of approximately 150 kilodaltons (Physicians Desk Reference, 2002, Medical Economics Company, Inc.). The Fc component of etanercept contains the constant heavy 2 (CH2) domain, the constant heavy 3 (CH3) domain and hinge region, but not the constant heavy 1 (CH1) domain of human IgG1. An Fc domain can contain one or all of the domains described above.
People suffering from some types of inflammatory diseases such as rheumatoid arthritis, plaque psoriasis, psoriatic arthritis, juvenile idiopathic arthritis, and ankylosing spondylitis, have an immune system that over produces tumor necrosis factor ("TNF"). Administration of etanercept has been found effective for treatment of some inflammatory diseases because it can reduce the levels of the active form of TNF in a subject by binding to TNF as a decoy receptor.
Etanercept can be produced in a known manner by recombinant DNA technology in a Chinese hamster ovary ("CHO") mammalian cell expression system. Unfortunately, the product that is produced by the CHO cells contains a large amount of incorrectly or misfolded and/or aggregated etanercept. For pharmaceutical use, it is desirable to provide etanercept that is relatively free of incorrectly folded and aggregated protein because the incorrectly folded/aggregated protein will not have the same therapeutic effect as the correctly folded protein, and may actually be detrimental to the patient.
Misfolding and aggregation frequently occur during production of recombinant proteins and hence must be addressed through downstream processes capable of separating the correctly folded protein from protein that is misfolded or aggregated. Misfolding reduces or eliminates the therapeutic effect of the protein. Aggregation, generally understood to involve non-covalent association of two or more etanercept homodimers to form very high molecular weight species, results in a similar loss of therapeutic effect, and occurs when proteins, including misfolded proteins, accumulate and clump together. As stated above, such misfolded proteins and protein aggregates are not only therapeutically ineffective, but may also be detrimental to the patient. Accordingly, the ability to purify a protein expression product containing etanercept so that properly folded etanercept is separated from misfolded and/or aggregated etanercept is important for obtaining etanercept that provides the highest possible degree of pharmaceutical acceptability.
Production of misfolded and aggregated proteins is not a problem specific to etanercept. There are many therapeutic proteins for which misfolding may be a problem. For example, misfolding of disulfide-containing proteins during refolding of recombinant proteins from Escherichia coli inclusion bodies is difficult to avoid, but can be effectively separated by reverse-phase chromatography with high resolution. The use of low pH and organic solvent in reverse-phase chromatography, however, can denature the proteins and may cause aggregation of the purified protein during the chromatography.
Even when misfolding is thought to be negligible during production of pharmaceutical proteins, e.g., in the case of mammalian secretory expression, aggregation and some misfolding may still occur (see e.g., Chi, E. Y., Krishnan, S., Randolph, T. W. and Carpenter, J. F., Physical Stability of Proteins in Aqueous Solution: Mechanism and Driving Forces in Nonnative Protein Aggregation, Pharm. Res., 20, 1325-1336 (2003); Kiese, S., Pappenberger, A., Friess, W., and Mahler, H. C., Shaken, Not Stirred. Mechanical Stress Testing of an IgG1 Antibody, J. Pharm. Sci., 97, 4347-4366 (2008)). Researchers have successfully separated non-native, misfolded proteins under non-denaturing conditions using aqueous chromatography employing ion exchange ("IEC") (see, e.g., Gagnon, P. J., Antibody Aggregate Removal by Hydroxyapatite Chromatography in the Presence of Polyethylene Glycol, Immunol. Methods, 336, 222-228 (2008); Gagnon, P., Purification Tools for Monoclonal Antibodies, Validated Biosystems, Tucson, Ariz., 57-87 (1996); Shukla, A. A., and Yigzaw, Y., Process Scale Bioseparations for the Biopharmaceutical Industry, Shukla, A., Etzel, M., and Gadam, S., eds., 179-227, CRC Press, Boca Raton (2007); Staby, A., Jacobsen, J. H., Hansen, R. G., Bruus, U. K., Jensen, I. H., Comparison of Chromatographic Ion-exchange Resins. V. Strong and Weak Cation-Exchange Resins, J. Chromatogr. A, 1118, 168-179 (2006); Shukla, A. A., Hubbard, B., Tressel, T., Guhan, S., Low, D. J., Downstream Processing of Monoclonal Antibodies-Application of Platform Approaches, Chromatogr. B, 848, 28-39 (2007); Shihara, T., Kadoya, T. J., Accelerated Purification Process Development of Monoclonal Antibodies for Shortening Time to Clinic: Design and Case Study of Chromatography Processes, Chromatogr. A, 1176, 149-156 (2007); Fahrner, R. L., Knudsen, H. L., Basey, C. D., Galan, W., Feuerhelm, D., Vanderlaan, M., Blank, G. S., Industrial Purification of Pharmaceutical Antibodies: Development, Operation, and Validation of Chromatography Processes, Biotechnol. Genet. Eng. Rev., 18, 301-27 (2001); and Yigzaw, Y., Hinckley, P., Hewig, A. and Vedantham, G., Ion Exchange Chromatography of Proteins and Clearance of Aggregates, Curr. Pharm. Biotech., 10, 421-426 (2009)), hydrophobic interaction ("HIC") (see e.g., Chen, J., Tetrault, J., Ley, A., Comparison of Standard and New Generation Hydrophobic Interaction Chromatography Resins in the Monoclonal Antibody Purification Process, J. Chromatogr. A., 1177, 272-81 (2008); Gagnon, P., and Grund, E., Large Scale Process Development for Hydrophobic Interaction Chromatography, Part 4: Controlling Selectivity, BioPharm, 9, 54-64 (1996); and Lu, Y., Williamson, B., and Gillespie, R., Recent Advancement in Application of Hydrophobic Interaction Chromatography for Aggregate Removal in Industrial Purification Process, Curr. Pharm. Biotech., 10, 427-33 (2009)) and hydroxyapatide ("HA") chromatography (see e.g., Aoyama, K., Chiba, J., Separation of Molecular Forms of Mouse IgG and IgM Monoclonal Antibodies in High Performance Liquid Chromatography on Spherical Hydroxyapatite Beads, J. Immunol. Methods, 162, 201-210 (1993); Luellau, E., Marison, W., von Stockar, U., Ceramic Hydroxapatite: A New Tool for Separation and Analysis of IgA Monocolonal Antibodies, in Animal Cell Technology, Carondo, M., ed., Kluwer Academic Publishers, Netherlands, 265-269 (1997); Luellau, E., von Stockar, U., Vogt, S., Freitag, R., Development of a Downstream Process for the Isolation and Separation of Monoclonal Immunoglobulin A Monomer, Dimers, and Polymers from Cell Culture Supernatant, J. Chomatogr. A., 796, 165-175 (1998); Yamakawa, Y., Chiba, J., High Performance Liquid Chromatography of Mouse Monoclonal Antibodies on Spherical Hydroxyapatite Beads, J. Liquid. Chromatogr., 11, 665-681 (1998); Coppola, G., Underwood, J., Cartwright, G., Hearn, M. T., High-performance Liquid Chromatography of Amino Acids, Peptides and Proteins: XCIII. Comparison of Methods for the Purification of Mouse Monoclonal Immunoglobulin MAutoantibodies, J. Chromatogr. A., 476, 269-290 (1989); Josics, D., Loster, K., Kuhl, R., Noll, F., Reusch, J., Purification of Monoclonal Antibodies by Hydroxylapatite HPLC and Size Exclusion HPLC, Biol. Chem. Hoppe-Seylars, 372, 149-156 (1991); Gagnon, P., and Beam, K., Antibody Aggregate Removal by Hydroxyapatite Chromatography, Curr. Pharm. Biotech. (2008)).
Prior teachings such as those referenced above have not proven useful for application to the separation of correctly folded etanercept from incorrectly folded etanercept in that they fail to provide qualitatively and/or quantitatively adequate samples. Accordingly, there is a need in the art for an effective and efficient separation technique for use with CHO cell produced etanercept capable of providing etanercept preparations of very high purity (i.e., in which incorrectly folded etanercept is either absent or present in present in very low levels) and in commercially attractive production yields.
The present invention employs so called "mixed mode" chromatography. A chromatography method for purifying recombinantly expressed proteins may generally be termed "mixed mode" when it utilizes at least two different forces to bind proteins and separate a desired protein product from undesired materials that may be present in a relatively impure expression product containing the desired protein along with undesired impurities. These forces can include, for example, electrostatic forces and hydrophobic forces.
Mixed mode chromatography works in a manner similar to more traditional chromatography techniques in that there is a stationary phase and a mobile phase. The stationary phase is normally an insoluble resin or gel, typically referred to as the chromatography resin, which provides the basis for the separation. The resin is contained in a column allowing liquids to pass through and contact the resin. The ability of the chromatography resin to separate desired material from undesired material is made possible by the presence of selected chemical groups, or moieties, that are conjugated to the resin. These conjugated groups, typically called ligands, give the resin the necessary affinity properties (i.e., electrostatic attraction properties resulting from ion exchange moieties present in the ligands, and hydrophobic attraction properties resulting from hydrophobic moieties present in the ligands) thereby enabling the resin to bind to some of the protein materials in an impure sample, but not others, when a solution containing the impure sample is allowed to flow through the chromatography column in contact with the resin.
The stationary phase of the chromatography column containing the resin with these affinity groups is packed inside the chromatography column which is typically a rigid cylindrical vessel into which fluid can be introduced at one end, contact the resin, and then exit the column at an opposite end. A solution containing the protein to be purified can be introduced into (and thus allowed to flow through) the column by placing the protein product into an appropriate solution and allowing the solution, called the mobile phase, to travel through the column. When the protein product to be purified (called the analyte) is presented to the column in the mobile phase, it reaches a state of equilibrium between the column and the mobile phase meaning that some of the material in the protein solution will attach, bind or become affixed to or captured by the affinity groups on the column resin, while the remainder of the material in the product will not attach to the column, but instead will flow through and out of the column where it can be collected for analysis, further processing, or it can be discarded.
Once a protein analyte has become bound to the column in the above-described manner, a washing step—typically called an elution step—is then used to elute, or release, the bound analyte from the column. Depending on the type of affinity ligands (e.g., charge based moieties or hydrophobic moieties, or a combination thereof, etc.) that are present on the resin to bind analyte to the column, the solution used for eluting or releasing the analyte from the column must have an affinity or an attraction to the analyte and/or the ligand (example charge properties, hydrophobic properties, pH properties, salt concentration, etc.) that can overcome the analyte's affinity, or attraction, to the resin, thereby causing the analyte to be released from the resin (the stationary phase referenced above) and into the elution medium (the mobile phase). Once released or eluted into the mobile phase, the analyte can then flow through and out of the chromatography column for eventual collection, analysis, etc, or transfer to further purification methods or filtration steps. It may be understood that whatever properties of attraction, or affinity, cause an analyte to bind to the chromatography resin (e.g, charge properties or hydrophobic properties), the mobile phase solution that is subsequently used to elute or release the analyte must have a competing set of properties such that the analyte then "prefers" to be in the elution medium rather than remaining captured on the column resin.
Compared to other single mode chromatography techniques, so-called mixed mode chromatography is unique in that the various binding and elution factors can be interdependent and can oppose one another. For example, increasing the ionic strength of the mobile phase in traditional single mode ion-exchange chromatography can drive elution or release of resin-bound analyte when the charged characteristics of an analyte have stronger attraction (preference) for the elution medium versus the attractive forces of the column resin. However, in a mixed mode chromatography method where the chromatography resin uses both electrostatic attraction as well as hydrophobic attraction to bind an analyte, increasing the ionic strength of the mobile (elution) phase can drive release of sample material from the column based on charge properties of that material, while at the same time driving or reinforcing binding of hydrophobic materials in the analyte because such hydrophobic protein materials—in the presence of charged based elution medium—will then tend to have a stronger attraction or preference to bind to the hydrophobic ligands of the column versus the charged environment of the elution medium. Accordingly, while an increase in the salt concentration may indeed drive a tendency to displace charged protein materials from the stationary phase when charged ions in the mobile phase compete with the protein for binding sites on the stationary phase-those portions of an analyte product mixture that may exhibit a higher degree hydrophobic character may have an enhanced tendency to remain bound to the hydrophobic moieties of the mixed mode chromatography column. The ability to exploit these phenomenon in any given protein separation context can hardly be considered predictable.
Two examples of mixed mode resins are Capto™ MMC and Capto™ Adhere (available from GE Healthcare). Capto™ MMC utilizes a ligand attached to a solid support matrix that may interact with the analyte by cation exchange (with its carboxylic group), hydrogen bonding, and hydrophobic interactions. Capto™ MMC's ligand is illustrated below:

Capto™ Adhere is similar to Capto™ MMC in that it also employs a ligand which is attached to a solid support matrix. The ligand, N-benzyl-N-methyl ethanol amine, also interacts with the analyte by anion exchange, hydrogen bonding, and hydrophobic interactions. Capto™ Adhere's ligand is illustrated below:

In both ligands, hydrophobic interaction is expected to be weak. Thus, if these ligands have only hydrophobic moieties (no charges), they would most likely require salting-out (protein precipitating) conditions for protein binding. However, having electrostatic interaction can make such weak hydrophobic interaction sufficient to provide additional binding force.

This patent is subject to a terminal disclaimer.

Correctly folded etanercept in high purity and excellent yield


An underwater exhaust system for a water-cooled marine engine installed in a boat whose hull is molded of fiber-reinforced resin. The system is adapted to exhaust underwater the gases and cooling water discharged from the engine via an internal fitting. The internal fitting is created by an exhaust port integral with the hull and formed of the same material, having a hydrodynamically-shaped main section defining a cavity whose mouth merges with the outer surface of the hull and an input section joined to the main section into which is fed the discharge from the engine. Telescoped into the cavity of the main section of the exhaust port and bonded thereto is a like-shaped main section of an external fitting having an output section joined to the main section to form an exhaust outlet from which the engine discharge is exhausted underwater.

1. Field of Invention
This invention relates generally to underwater exhaust systems for marine engines, and in particular to a system installed in a boat whose hull is molded of fiber-reinforced resin, the system including an internal fitting that is integral with the hull and an external fitting telescoped in the internal fitting and extending from the hull to exhaust underwater the cooling water and gases discharged from the operating engine.
2. Status of Prior Art
To propel a boat, the boat machinery for this purpose consists principally of an onboard propulsion engine, a propeller and drive line components. Marine engines are almost exclusively of the familiar internal combustion types, gasoline or diesel. Gasoline engines have traditionally dominated the pleasure and sports boat field, while diesel engines are favored for commercial and military craft.
A typical marine engine includes a water cooling system; hence discharged from the operating engine are cooling water as well as exhaust gases. The boat therefore must be provided with an exhaust system for the discharge. An above water exhaust system for this purpose typically includes exhaust ports exiting through the transom of the boat.
Because of air passing around and behind the transom, exhaust gases are drawn into the cockpit, this being known, as the "station wagon effect." Even at idle, gases still linger at the stern of the boat. Moreover in a following breeze, gases are blown into the cockpit. Not only is the cockpit polluted by noxious exhaust gases, but engine noises are conveyed thereto by the exhaust system, and this makes the cockpit noisy.
A typical underwater exhaust system for a boat has a bronze fitting that is bolted to the hull and extends therefrom into the water. Should the bronze fitting extending From the hull be struck by an object, the fitting itself may not break off, thereby ripping a large hole in the hull with serious consequences.
Motor-driven sports and pleasure boats having hulls molded of fiberglass-reinforced resin are now commonplace. Such hulls must include through-fittings, such as one to accommodate the propeller shaft extending from the engine installed in the boat. And the hull must also include a fitting for an underwater exhaust system for the cooling water and gases discharged from the engine. If this exhaust system is of the conventional type, then it suffers from the above-noted drawbacks.
In our copending Strong et al. application above-identified, there is disclosed a molded fiberglass-reinforced resin boat hull provided with in situ holes to accommodate through-hull fittings, such as a fitting adapted to receive a rudder post.
This boat hull is molded on a female mold having locating holes drilled therein in registration with the holes to be formed in the hull. Anchored by a bolt locked in each locating hole is a plug of non-stick material, such as UHMW polyethylene, which projects above the female mold and has a configuration defining the hole to be formed in situ in the hull. Laid down on the female mold and about the projecting plugs are the reinforcing fiberglass materials which are impregnated with a flowable uncured resin for creating the hull. When the resin is cured, it is not bonded to the plugs whose anchoring bolts are removed to expose the in situ holes. The finished hull is then withdrawn from the female mold. In the case of the in situ hole for receiving a through-hull fitting for a rudder port, the in situ hole for this purpose has an internally-threaded cylindrical extension into which the externally-threaded rudder port is received.
In an underwater exhaust system in accordance with the invention, the system includes an exhaust port formed by an internal fitting which is integral with the molded fiber-reinforced hull. This internal fitting is produced in a manner similar to that in which in situ holes in a molded hull are created in our Strong et al. co-pending application.

Underwater exhaust system for marine engine


A light emitting device includes a semiconductor light emitting element including a semiconductor stacked-layer body and an electrode disposed on a first surface of the semiconductor stacked-layer body; a resin member disposed on a first surface side of the semiconductor stacked-layer body; and a metal layer disposed in the resin member and electrically connected to the electrode. A recess is defined in an upper surface of the resin member. The metal layer is projected from the upper surface of the resin member, and is disposed to surround at least a portion of the recess.

1. Technical Field
The present disclosure relates to a light emitting device that includes a semiconductor light emitting element and a resin member provided with an internal wiring, and to a method of manufacturing the same.
2. Description of the Related Art
Light emitting devices using a semiconductor light emitting element such as a light emitting diode are widely used because of ease of miniaturization and high light emission efficiency. The light emitting elements used in light emitting devices can be roughly divided into two types, namely, a face up type in which a surface of a semiconductor light emitting element for disposing a pad electrode is on the opposite side from the mounting surface, and a face down type in which a surface of a light emitting element for disposing an electrode is a lower surface that faces a mounting substrate.
In the face up type, a semiconductor light emitting element is mounted on leads or the like, and the semiconductor light emitting element and the leads are connected via bonding wires or the like. Accordingly, in a plan view of a semiconductor light emitting element disposed on a mounting substrate—that is, seen from a perpendicular direction relative to the mounting surface of the mounting substrate—portions of the wires are needed to be outer side of the semiconductor light emitting element, which imposes a limitation in miniaturization of the light emitting element.
On the other hand, in the face down type (or flip chip type), a pad electrode disposed on a surface of a semiconductor light emitting element and a wiring disposed on a mounting substrate can be electrically connected via a connector such as a bump or a metal pillar, which are positioned within the outer peripheral line of the semiconductor light emitting element in a plan view seen from a direction perpendicular to the mounting surface of the mounting substrate. This configuration allows forming of a CSP (Chip Size Package or Chip Scale Package) in which the size of a light emitting device (particularly the size in a plan view seen from a direction perpendicular to the mounting surface of the mounting substrate) is reduced almost to the size of the chip of a semiconductor light emitting element.
In recent years, in order to achieve further miniaturization, or in order to further improve the light emission efficiency, a face down type light emitting device has been proposed, in which a growth substrate (a light-transmissive substrate) such as sapphire has been removed, or the thickness of the growth substrate has been reduced.
The growth substrate is a substrate for growing thereon an n-type semiconductor layer and a p-type semiconductor layer that are components of a semiconductor light emitting element. The growth substrate also exhibits the effect of improving the mechanical strength of the light emitting device by supporting a semiconductor light emitting element that is small in thickness and low in strength. Accordingly, in a light emitting device in which the growth substrate is removed or the thickness of the growth substrate is reduced after formation of a semiconductor light emitting element, for example as disclosed in JP 2011-249426 A, a resin layer is disposed on an electrode side (the side facing the mounting substrate) for supporting a bare chip (i.e., a semiconductor light emitting element), and internal wirings made of metal pillars or other wirings are formed so as to penetrate through the resin layer, and the electrode and an external terminal are electrically connected to each other. With such a resin layer that includes an internal wiring, sufficient mechanical strength can be reliably obtained.
In the case where such a light emitting device that has a resin layer disposed on the electrode side is mounted on a mounting substrate by using an electrically conductive adhesive member, for example using a solder and a reflowing method, melted solder may be squeezed out from between the electrode for external connection of the light emitting device and the wiring pattern of the mounting substrate. In particular, when the solder is excessively supplied, the solder squeezed out from between the electrode for external connection of the light emitting device and the wiring pattern of the mounting substrate may rise along a side surface of the resin layer. The solder that rises up the side surface of the resin layer may cause bonding defects between the light emitting device and the mounting substrate, or may contaminate the light extraction surface resulting in a reduction in the light extraction efficiency.

Light emitting device and method of manufacturing light emitting device


A toggle-type switch employing a cam controlled toggle lever to move or permit to move resilient arms on which are located movable contacts into engagement with fixed contacts. The number of resilient arms and movable contacts and the number of fixed contacts is selected to make and break tie desired number of circuits. The manner in which the circuits are closed or opened depends upon the shape of the cam surface and the cam is spring loaded to hold the toggle in a selected position on a momentary or maintained basis. A slider cooperates with the toggle lever to move selected movable contacts into contact with fixed contacts or allows movable contacts to move out of engagement with other fixed contacts.

1. Field of the Invention
The invention is directed to electrical switches for home and commercial use and more particularly to switches of the toggle-type operated by a toggle handle.
2. Description of the Prior Art
In the usual toggle-type switch the toggle handle is supported for pivotal movement with respect to the housing and moved by the switch operator. The lower end of the toggle handle is spring loaded to take one of two over-center positions. By providing suitable contacts, such over-center mechanisms give positive on/off operation as well as single pole, double throw and double pole, double throw switch operations. Momentary switches are more difficult to make because there is no positive feel that the switch has been closed and center-off switches are not possible at all. Additionally, complex spring arrangements are required to position the movable central pole on both single and double pole switches. Also, the over-center spring action causes the poles to snap from one set position to the other making the switch reasonably noisy.


An active tester for vehicle circuit evaluation includes a signal source for generating a dynamic signal, such as an AC current, for injecting to a circuit under test. The tester includes a data storage device for storing at least one test parameter and a data processor for processing data. In operation, the data processor controls to apply the dynamic signal to the separated points of the circuit via the first set of terminals. The response of the circuit under test to the applied dynamic signal is measured. The data processor determines a dynamic parameter of the circuit under test as a function of the dynamic signal and the response. The data process then generates a test result related to the characteristics of the circuit as a function of the at least one test parameter and the determined dynamic parameter. The test result is compared with specification values to determine whether the circuit under test works normally.

In the automotive industry, it has been a known practice to evaluate the health of starting and/or charging circuit components by measuring a voltage drop corresponding to a specific input current between two separate points of the circuit, and comparing the measurement with specification values. For instance, for determining the health of a starting circuit (which may include a starter, a battery, a solenoid, cables and terminals) in an automotive vehicle, a technician is often asked to use a voltmeter to measure a voltage drop between the positive terminal of the starter and the positive terminal of the vehicle's battery while the starter is cranking the engine. This can be a cumbersome task, sometimes requiring an additional technician to monitor the voltage display while the other technician cranks the vehicle at the same time. If the current flowing through to the starter is normal, the measured voltage drop will be within an acceptable range specified by the manufacturer. If an abnormal voltage drop is found, further investigation may be needed to determine the cause of the abnormality. For example, a possible cause to the abnormal voltage drop may be that the resistance or impedance of a cable connecting the starter and battery is too high. In order to isolate the source of the problem, the technician needs to remove the connecting cable from the starting circuit and uses an ohmmeter to measure the resistance of the cable to determine whether the cable resistance indeed contributes to the abnormal voltage drop. If the cable resistance is normal, the technician will then check the integrity of the connections of the cable terminals to the starter and the cable to the battery. Rust and corrosion are common problems with the terminal connections of the cable which add unwanted resistance to this circuit.
For determining the health of a charging circuit (which includes a battery charged by an alternator, and cables and terminals) in an automotive vehicle, a technician often is asked to use a voltmeter to measure a voltage drop between the positive terminal of the alternator and that of the battery charged by the alternator when the charging circuit is in operation, i.e., a current generated by the alternator is flowing through the battery, to determine whether the measured voltage drop falls within an acceptable range specified by specifications. If an abnormal voltage drop is found, further investigation may be needed to determine the cause of the abnormality. For example, a possible cause to the abnormal voltage drop may be that the resistance or impedance of a cable connecting the alternator and battery is too high. In order to isolate the source of the problem, the technician needs to remove the connecting cable from the charging circuit and uses an ohmmeter to measure the resistance of the cable to determine whether the cable resistance indeed contributes to the abnormal voltage drop.
A shortcoming of the conventional approach is that the multiple steps for measuring the voltage drop and work involved to measure the cable resistance add complexity to the testing procedure and it can be time consuming, thus adding additional expense to the repair cost. Furthermore, the conventional approach requires the starting circuit or charging circuit to be in operation, such that a voltage drop can be measured by the voltmeter. However, the circuit under test is not always in working condition or in operation. In that case, no current is flowing through the circuit, and no voltage drop can be detected by the voltmeter. As a result, the test cannot be performed. Moreover, the specification of a vehicle may require comparing voltage drops using different testing parameters, such as varying starter currents under different engine conditions or different charging currents under different loads.
The starter current can vary depending on temperature and the engine's operating condition. However, it is not always possible to generate or duplicate the required testing parameters as required by the specification. Even if it is possible, it is burdensome to perform multiple tests using various test parameters.
Therefore, a need exists for a tester that would reduce the complexity of circuit testing procedures. There is also a need for a tester that could determine the health of circuits even if the circuits are not in operation or working condition. Another need exists to allow a user to predict circuit responses corresponding to different testing parameters, without the need to actually conduct multiple tests using the different testing parameters.

Active tester for vehicle circuit evaluation


A current-steering type digital-to-analog converter (DAC) is disclosed. The DAC includes a first sub-DAC, a second sub-DAC and a controlling device. Both the first sub-DAC and the second sub-DAC are configured to receive input signals. The controlling device selectively and periodically sends output signals of either the first sub-DAC or the second sub-DAC to a resistive load while sending output signals of the remaining one of the two sub-DACs to a dummy resistive load. An output of the DAC is provided at the resistive load.

1. Technical Field
The present invention relates to mixed-signal circuits in general, and in particular to digital-to-analog converters. Still more particularly, the present invention relates to a current-steering type digital-to-analog converter.
2. Description of Related Art
Digital-to-analog converters (DACs) are electronic circuits for converting signals from a digital domain, where signals are typically represented by discrete quantities, to an analog domain, where signals are typically represented by continuous quantities. Well-known DAC types include resistor-string, charge-redistribution, and current-steering.
Any of the above-mentioned DAC types may use a binary-weighted design, a thermometer-code design, or a combination of both designs to convert a digital signal to an analog signal. With a binary-weighted design, analog signals are generated from an array of binary-weighted elements that can be capacitors, resistors, or current sources. The advantage of a binary-weighted design is compactness. With a thermometer-code design, analog signals are generated from an array of unit elements that can be capacitors, resistors, or current sources. Advantages of a thermometer-code design include monotonic input-output transfer characteristic and reduced glitch energy during switching transients.
For current-steering type DACs, it is often a sensible choice to have the most-significant bits (MSBs) implemented with the thermometer-code design, while the least-significant bits implemented with the binary-weighted design. The combination of the two designs is a tradeoff between implementation cost (such as chip size) and performance (such as improved monotonicity and reduced glitch energy).
One problem with conventional current-steering type DACs is that their internal bias points are often forced to change to accommodate output values during switching transients from one value to the next. Each time an internal bias point, such as the common-source node of the current-steering transistors, changes due to a change in the DAC's output value, parasitic capacitors associated with the internal bias node need If such charging or discharging affects the output signal in a non-linear way, the dynamic performance of the DAC will be compromised. Consequently, it is desirable to provide an improved current-steering type DAC.

Current-steering type digital-to-analog converter