A method for transmitting light in an image display system includes generating a beam of light from a light source. The beam of light is directed at a first segment of an electronically-switchable filter. A first portion of the beam of light is accepted by the first segment of the electronically-switchable filter, and a second portion of the beam of light is rejected by the first segment of the electronically-switchable filter. The first portion of the light beam is modulated to produce at least a portion of a displayed image. The second portion of the light beam is recycled to redirect the second portion of the light beam at a second segment of the electronically-switchable filter. The second portion of the light beam is accepted by the second segment of the electronically-switchable filter. The second portion of the light beam is modulated to produce at least a portion of the displayed image.

Spatial light modulators used in sequential color display systems are capable of projecting image details from media sources such as HDTV, DVD, and DVI. Viewers evaluate display systems based on many criteria such as image size, resolution, contrast ratio, color purity, and brightness. Image brightness is a particularly important metric in many display markets since the available brightness can limit the image size of a projected image and controls how well the image can be seen in venues having high levels of ambient light. Projection display designers increase the brightness of a given projection display by increasing the light source used to form the image. Increasing the light source, however, also increases the cost, size, and weight of the display system. Additionally, larger light sources generate additional heat that must be dissipated by the display.
Many other factors affect the brightness of the images produced by the display system. One of the major factors is the number of modulators used to modulate the light used to produce the image. Display systems that use a modulator with a very fast response time, such as the digital micromirror device (DMD®), can use a single modulator to create a full color image. Other display systems use three modulators, such as liquid crystal display (LCD) panels or DMDs, to create a full color image. The disadvantage of the single-modulator sequential color display system is its low image brightness. Because the white light source is time-divided into three or more primary color light beams, most of the light at any given time is not used. For example, when the blue primary color image is being formed, the green and red output of the white light source are filtered out of the light beam and "dumped." Thus, a sequential color display system, while generally less expensive than the three-modulator display system, makes relatively inefficient use of the light produced by the light source.
In addition to reducing the brightness of the image produced by the display system, discarding or "dumping" portions of light creates other problems for the display system. For example, the light filtered out of the light beam generally becomes stray light that the display system must control to prevent the filtered light from reaching the image plane and degrading the contrast of the displayed image. Additionally, the filtered light is generally converted to heat, which must be dissipated by using large fans that increase the noise produced by the display system and increase the size of the display system.

Sequential color recapture for image display systems


A handrail for an escalator or moving walk that has a fixed guide device and a handrail body that moves along the guide device when in operation is disclosed. The guide device has a form-giving guide section that contains a lip-guide that extends along a longitudinal direction of the guide section. The handrail body is strip-shaped and has two edge-lips that extend along two longitudinal edges of the strip-shaped handrail body. The edge-lips are formed in such manner that they run parallel to the longitudinal direction when the handrail body moves in the lip guide. The guide section essentially defines the form of the handrail in both the direction parallel to the longitudinal direction and in a cross-sectional plane perpendicular to the longitudinal direction.

There are numerous embodiments and designs for the handrail of an escalator or moving walk.
To give the passenger a safe grip, handrails are known to have a C-shaped cross section and are usually constructed from a number of different materials. The stability of the C-shaped handrail must be assured over its entire life since for safety reasons the gap between the moving handrail and a stationary balustrade must be minimal. Lifting of the handrail by the passenger must also be prevented.
As a result of the required form stability and safety requirements, such handrails have a large volume and high lip rigidity, i.e. a high rigidity of the side areas of the handrail. On account of such form stability, and especially on account of the lip rigidity, a high degree of formability of the handrail is required. For stability and lip rigidity hinder bending of the handrail in the longitudinal direction, particularly in reversing curves, transitional curves, and on the handrail driving wheel. On account of the greater volume and therefore greater weight of the handrail, a drive with a high power output is required to move the handrail.
In addition, a so-called gliding layer that is provided on the inside of the handrail must fulfill two functions simultaneously. The gliding layer is the contact surface of the handrail not only for the handrail guide but also for the handrail drive system. The gliding surface must therefore have good gliding properties with low sliding friction. However, since the same surface is used for driving, it must also have very good static friction since otherwise the handrail cannot be driven.
From Japanese patent publication JP06064881-A of the Hitachi company, a handrail is known that is easy to grip and safe. The handrail has a robust, stationary guiderail. A guiderail embraces a handrail body that moves along the guiderail when the moving walk is in operation. In the area of a machine room, the guiderail—and therefore also the handrail body—has a different cross-sectional form than in the area that is accessible to people.
This constellation is disadvantageous, as the relatively large contact area between the inside of the handrail body and the guiderail causes friction and wear. However, especially critical for safety reasons is the size of the gap between the moving handrail body and the stationary guiderail.
An objective of the present invention is to present an escalator or moving walk of the type stated at the outset that enables safety for the passenger to be improved relative to present solutions.
A further objective of the present invention is to present an escalator or moving walk of the type stated at the outset that has less friction and reduced wear.
Yet a further objective is to improve the driving efficiency for the handrail.

Handrail for an escalator or moving walk and escalator or moving walk with such a handrail


A bicycle helmet has a body with a concave inner surface configured to permit the helmet to fit a user's head. The helmet also includes a reinforcement structure having a plurality of separate frames interconnected with each other, at least one of the plurality of frames comprising a unidirectional filament, wherein the reinforcement structure engages the body.

1. Field of the Invention
The present invention relates to protective helmets and bicycle helmets in particular. More specifically, the present invention relates to a helmet with a unidirectional filament internal reinforcement structure.
2. Description of the Related Art
Conventional bicycle helmets typically employ a layer of crushable material, usually synthetic resin foam, extending over and about the wearer's head to mitigate the force of an impact, for example, due to a fall. Conventional helmets also sometimes include an outer shell attached to the layer of crushable material, which serves to increase the impact strength of the helmet, and serves as a structural support for the crushable material. Other helmet designs include materials of different densities covered by an outer shell. However, both these approaches tend to increase the overall weight of the helmet. Additionally, increasing the addition of a shell increases the thickness of the helmet, making it more bulky.
Accordingly, there is a need for a helmet design that provides a desired structural support with minimal increase in the overall weight of the helmet.

This patent is subject to a terminal disclaimer.

Bicycle helmet with reinforcement structure


A vibration control apparatus designed specifically for use on space vehicles includes a stator for mounting in the vehicle, a lower flotor, magnetically levitated on the stator, an upper flotor nested in and magnetically levitated on the lower flotor, and position, orientation and motion sensors carried by the stator and flotors. When any changes in position, orientation or movement, i.e. vibration of apparatus is detected, magnetic force actuators are energized to compensate for such changes to keep a work platform on the upper flotor virtually vibration-free. Moreover, controlled and induced vibration of the work platform and an experiment carried thereby can be effected using the lower flotor as a reaction mass, i.e. without feedback to the vehicle.

1. Field of the Invention
This invention relates to a vibration control apparatus, and in particular to a microgravity vibration control apparatus.
2. Discussion of the Prior Art
At low frequencies ( less than 0.01 Hertz) space platforms such as the shuttle and the International Space Station (ISS) provide a unique, near ideal free-fall environment, which can be used to conduct material science, fluid physics and crystal growth experiments. Departure from ideal free fall due to atmospheric drag, rotational effects and gravity gradient are of the order of a micro-g (10xe2x88x926 g). However, above 0.01 Hz spacecraft vibrations are such that acceleration levels typically exceed 10xe2x88x923 g. Experiments conducted on the space shuttle and on MIR have shown that these vibration levels can significantly affect results. Vibrations, which are sometimes referred to as g-jitter, are driven by on-board activities such as attitude control systems, thermal control systems, air conditioning systems, power generation systems, crew activity and the operation of the spacecraft resulting in vibration environments characterized by milli-g (10xe2x88x923 g) acceleration levels. On the space shuttle, vibration levels in the frequency band 0.01 Hz to 100 Hz are in the range of 10xe2x88x923 g Root Mean Square (RMS), with peaks typically exceeding several milli-g. These are sufficient to cause significant disturbances to experiments that have fluid phases, which includes many material science experiments. The acceleration environment of the International Space Station will likewise not be as clean as originally hoped for, and the ISS will not meet the current vibratory requirements without the use of vibration isolation apparatuses of the type described herein.
In order to isolate fluid science experiments from spacecraft vibrations, the Canadian Space Agency (CSA) developed a so-called Microgravity Vibration Isolation Mount (MIM), which constitutes a first generation of the present invention. The MIM was operational for more than 3000 hours on the Mir space station between May 1996 and January 1998. A second generation MIM was flown on space shuttle mission STS-85 in August 1997.
The MIM includes two major components, namely a stator which is fixed to 10xe2x88x923 the spacecraft and a flotor on which is mounted an experiment to be isolated. Positions sensing devices track the position and orientation of the flotor with respect to the stator, and accelerometers monitor stator and flotor accelerations. The position sensing devices and accelerometers are used in an active control loop including magnetic actuators for moving the flotor relative to the stator to compensate for even extremely small vibrations of the stator.
There is a large volume of patent literature relating to vibration isolation and damping systems. Examples of such literature include U.S. Pat. No. 2,788,457 (Griest); U.S. Pat. No. 3,088,062 (Hudimac); U.S. Pat. No. 4,088,042 (Desjardins); U.S. Pat. No. 4,314,623 (Kurokawa); U.S. Pat. No. 4,432,441 (Kurokawa); U.S. Pat. No. 4,585,282 (Bosley); U.S. Pat. No. 4,595,166 (Kurokawa); U.S. Pat. No. 4,874,998 (Hollis Jr.); U.S. Pat. No. 4,710,656 (Studer); U.S. Pat. No. 4,724,923 (Waterman); U.S. Pat. No. 4,848,525 (Jacot et al); U.S. Pat. No 4,874,998 (Hollis Jr.); U.S. Pat. No. 4,929,874 (Mizuno); U.S. Pat. No. 4,947,067 (Habermann et al); U.S. Pat. No. 5,022,628 (Johnson et al); U.S. Pat. No. 5,168,183 (Whitehead); U.S. Pat. No. 5,236,186 (Weltin et al); U.S. Pat. No. 5,285,995 (Gonzalez et al); U.S. Pat. No. 5,368,271 (Kiunke et al); U.S. Pat. No. 5,385,217 (Watanabe et al); U.S. Pat. No. 5,392,881 (Cho et al); U.S. Pat. No. 5,400,196 (Moser et al); U.S. Pat. No. 5,427,347 (Swanson et al); U.S. Pat. No. 5,427,362 (Schilling et al); U.S. Pat. No. 5,445,249 (Aida et al); U.S. Pat. No. 5,446,519 (Makinouchi et al); U.S. Pat. No. 5,483,398 (Boutaghou); U.S. Pat. No. 5,542,506 (McMichael et al); U.S. Pat. No. 5,584,367 (Berdut); U.S. Pat. No. 5,609,230 (Swinbanks); U.S. Pat. No. 5,638,303 (Edberg et al); U.S. Pat. No. 5,645,260 (Falangas); U.S. Pat. No. 5,718,418 (Gugsch); U.S. Pat. No. 5,744,924 (Lee); U.S. Pat. No. 5,765,800 (Watanabe et al); U.S. Pat. No. 5,844,664 (Van Kimmenade et al); U.S. Pat. No. 5,876,012 (Haga et al); U.S. Pat. No. 5,925,956 (Ohzeki); U.S. Pat. No. 6,031,812 (Liou), and WO 99/17034 (Nusse et al) and WO 00/20775 (Ivers et al).
Some fluid phase experiments require controlled and induced vibration of the experiment, with no reaction back to the space vehicle. While a system of the type described above, including a stator and flotor, provides vibration damping, such a system cannot be used to effect such controlled and induced vibration.
The object of the present invention is to meet the need defined above by providing a vibration control apparatus which can effect controlled and induced vibration of an experiment with no disturbance to the space station. Coincidentally, the apparatus of the present invention is inherently more efficient at damping vibration than a two-stage system.
Accordingly, the invention provides a vibration control apparatus comprising:
(a) stator means for mounting on a fixed surface;
(b) lower flotor means normally spaced apart from said stator means in nesting relationship thereto;
(c) an upper flotor means normally spaced apart from said lower flotor means in nesting relationship thereto;
(d) work platform means on said upper flotor means;
(e) position sensing means associated with said stator means, lower flotor means and upper flotor means for determining the position and orientation of said lower flotor means and said upper flotor means relative to said stator means;
(f) accelerometer means associated with said stator means, lower flotor means and upper flotor means for determining acceleration of said lower flotor means and upper flotor means with respect to inertial space; and
(g) vertical and horizontal magnetic force actuator means associated with said stator means, lower flotor means and upper flotor means for imparting motion to said lower flotor means and to said upper flotor means to compensate for vibration of said stator means, whereby vibration of said work platform is minimized.


An improved surge protecting circuit which can protect the power source and the internal and external circuit elements of an electronic product by absorbing external surges through ground. The protecting circuit according to the present invention is connected between an AC input terminal and an AC ground pattern. The protecting circuit includes surge absorption patterns having an arc discharge gap of preferably 0.25 mm, which is less than a specified safety distance, which is typically 5 mm, so as to absorb the external surges transmitted through the terminal to the AC ground pattern and a varistor connected between the surge absorption patterns and the AC ground patterns.

1. Field of the Invention
The present invention relates to an improved surge protecting circuit for electronic products and, more particularly, to a surge protecting circuit which can protect the power source and the internal and external circuit elements of an electronic product by absorbing external surges through ground.
2. Description of the Related Art
Generally, since various electronic products such as televisions or video cassette recorders are connected to an antenna, they are subject to damage caused by external surges, such as lightning, which may conduct through the antenna to the electronic product. Therefore, there are certain safety measures which may be taken to protect the products from these external surges.
For example, referring to FIG. 1, an AC (alternating current) ground pattern 12 of an AC (alternating current) input circuit 10 of a conventional electronic product is grounded through an AC input node having a current path to ground, whereas a DC (direct current) ground pattern 22 of a DC operating circuit 20, which is operated by receiving power through a secondary winding of a transformer T from the AC input circuit 10, is electrically floated. Therefore, external surges received by the DC operating circuit 20 through an antenna are transmitted to the AC ground pattern 12 through the DC ground pattern 22 by an arc discharge between terminals 32 and 34 of a surge protecting pattern 30, and absorbed to the ground through the AC input node.
An arc discharge gap between the terminals 34 and 32 of the surge protecting pattern 30 is specified to a safety distance, which is typically 5 mm. The terminals 34 and 32 of the surge protecting pattern 30 should be separated from each other by the specified safety distance or more in order to prevent impulse noise generated from an AC power source from being transmitted to the DC operating circuit 20 through the arc discharge gap. Although this safety distance is effective to isolate the noise generated by the AC power source, it is not as effective to provide substantial protection against damage to the DC operating circuit from external surges.
Recently, due to the increasing use of components such as microprocessors and integrated circuits in electronic products, which components are more sensitive to electrical surges, the industry has demanded a more definite protection against such surges.

Electronic products with improved surge protecting circuit


Methods, systems, and computer readable media for automated intraoperative surgical guidance in medical images are disclosed. A system and method generally for analyzing subject image data, calculating surgical decision risks and autonomously providing recommended pathways or actions that support the decision-making process of a surgeon to predict optimized implant and subject outcomes (ex. implant guidance, fracture reduction, anatomical alignment) by a graphical user interface.

Many of the radiographic parameters essential to total hip arthroplasty (THA) component performance, such as wear and stability, can be assessed intraoperatively with fluoroscopy. However even with intraoperative fluoroscopic guidance, the placement of an implant or the reduction of a bone fragment can still not be as close as desired by the surgeon. For example, mal-positioning of the acetabular component during hip arthroplasty can lead to problems. For the acetabular implant to be inserted in the proper position relative to the pelvis during hip arthroplasty requires that the surgeon know the position of the patient's pelvis during surgery. Unfortunately, the position of the patient's pelvis varies widely during surgery and from patient to patient. During trauma surgery, proper fracture management, especially in the case of an intra-articular fracture, requires a surgeon to reduce the bone fragment optimally with respect to the original anatomy in order to: provide the anatomical with joint the best chance to rehabilitate properly; minimize further long-term damage; and, if possible, to regain its normal function. Unfortunately, in a fracture scenario, the original anatomical position of these bone fragments has been compromised and their natural relationship with the correct anatomy is uncertain and requires the surgeon to use his/her best judgment in order to promote a successful repair and subsequent positive outcome.
Various devices are known to reduce mal-positioning of these surgical components. For example, a transverse acetabular ligament has been suggested as a qualitative marker of the orientation of the acetabulum. (Archbold H A, et al. The Transverse Acetabular Ligament; an Aid to Orientation of the Acetabular Component During Primary Total Hip Replacement: A Preliminary Study of 200 Cases Investigating Postoperative Stability, J Bone Joint Surg BR. 2006 July; 88(7):883-7). However, it has been suggested that the acetabulum can be deteriorated due to arthritis. Others have proposed using a tripod device that uses the anatomy of the ipsilateral hemi pelvis as the guide to position the prosthetic acetabular component. U.S. Patent Publication Number 20090306679. This instrument has three points. The first leg is positioned in the area of the posterior inferior acetabulum, a second leg is positioned in the area of the anterior superior iliac spine and a third leg is positioned on the ileum of the subject. U.S. Patent Publication Number 20090306679. Regarding fracture fixation, or a correction of a deformity or malunion, various devices have also been suggested to support proper reconstruction and/or reduction of bone fragments. For example, a distal radius volar fixation plate has been suggested to act as an invasive, intraoperative quantitative supporting buttress to fix and provide a reference to the surgeon in order to help realign the broken bony anatomy.
Distortion in a radiographic image, particularly fluoroscopic images, is a well-known phenomenon (Jares̆ V. The effect of electron optics on the properties of the x-ray image intensifier. Adv Electron Elect Phys. Oct. 9, 1985; 64(8): 549-59). Several distortion correction techniques have been published to date, for example by Kedgely A E, et al. in J Appl Clin Med Phys. 2012 Jan. 5; 13(1):3441. doi: 10.1120/jacmp.v13i1.3441. Image intensifier distortion correction for fluoroscopic RSA: the need for independent accuracy assessment. These methods attempt to correct the distortion using a series of beads to calibrate the amount of distortion in an image and then attempt to correct that distortion to a non-distorted image of the image. A need exists in the industry to allow for intraoperative live adaptation of a grid (analogue, virtual, augmented, hologram, or 3D shape model) for use in measurements, positioning of implants, and alignment of anatomy and to provide distortion adaptation with a radiographic grid alignment device.
Additionally, during a surgery, a surgeon is required to make real-time decisions that can be further complicated by the fact that there are multiple decisions needing to be made at the same time. At any given time, there can be a need for a decision made on a fracture reduction guidance for example and simultaneously a decision required on implant placement and an error at any stage will likely increase the potential for a sub-optimal outcome and potential surgical failure. Unfortunately, most of these problems are only diagnosed and detected postoperatively and oftentimes lead to revision surgery. These risks and patterns need to be identified in real-time during the surgical or medical event. As surgeons and medical professionals must often rely solely on themselves to identify hazards and risks or make decisions on critical factors in, and surrounding, a surgical event, a need exists for a system and method that can provide intraoperative automated intelligence guided surgical and medical situational awareness support and guidance.


A method for operating a receiving device includes determining reliability ratings for undecoded data streams in a received transmission, selecting an undecoded data stream in the received transmission in accordance with the determined reliability ratings, thereby producing a selected data stream, and decoding the selected data stream with a decoding trellis, thereby producing a data symbol. The method also includes updating the decoding trellis in accordance with the data symbol, and repeating the selecting, the decoding, and the updating for remaining undecoded data streams in the received transmission.

Wireless interconnectivity has freed users from being tied down to fixed locations and wired connections. Through wireless interconnection networks, users are free to work and/or play wherever there is service. The use of wireless connections continues to grow dramatically year after year. Therefore, the need for systems and methods for providing greater and greater bandwidth also continues to grow.

System and method for faster than Nyquist transmission


A method for transmitting, by a base station, configuration information for a reference signal for channel measurement. The method according to one embodiment includes transmitting, to a user equipment, first resource information for indicating a first pattern, first subframe information for indicating a first subframe, second resource information for indicating a second pattern, and second subframe information for indicating a second subframe. The first subframe information includes information indicating a first periodic interval, and the second subframe information indicates information indicating a second periodic interval. Each of the first and second subframes is comprised of two slots—slot 0 and slot 1, and each of the first and second reference signal time-frequency resources is within two OFDM symbols other than OFDM symbols 0, 1, 2, and 3 of the slot 0 and other than OFDM symbols 0, 1, and 3 of the slot 1.

1. Field of the Invention
The present invention relates to a method for efficiently transmitting Reference Signals (RSs) in a Multiple Input Multiple Output (MIMO) communication system, under an environment where antennas are added to an existing system.
2. Discussion of Related Art
Long Term Evolution (ITE) Physical Structure
3rd Generation Partnership Project (3GPP) supports a type-1 radio frame structure for application in Frequency Division Duplex (FDD) and a type-2 radio frame structure for application in Time Division Duplex (TDD).
FIG. 1 illustrates the type-1 radio frame structure. A type-1 radio frame includes 10 subframes each having two slots.
FIG. 2 illustrates the type-2 radio frame structure. A type-2 radio frame includes two half frames each having 5 subframes, a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP), and an Uplink Pilot Time Slot (UpPTS). Each subframe includes two slots. The DwPTS is used for initial cell search, synchronization, or channel estimation in a User Equipment (UE), whereas the UpPTS is used for channel estimation in a Base Station (BS) and uplink transmission synchronization in a UE. The GP is a period between a downlink and an uplink, for eliminating interference with the uplink caused by a multi-path delay of a downlink signal. Irrespective of the types of radio frames, each subframe includes two slots.
FIG. 3 illustrates an LTE downlink slot structure. Referring to FIG. 3, a signal transmitted in each downlink slot may be described by a resource grid with NRBDL NscRB subcarriers by NsymbDL Orthogonal Frequency Division Multiplexing (OFDM) symbols. NRBDL represents the number of downlink Resource Blocks (RBs) and NscRB represents the number of subcarriers per RB. NsymbDL represents the number of OFDM symbols in the downlink slot.
FIG. 4 illustrates an ITE uplink slot structure. Referring to FIG. 4, a signal transmitted in each uplink slot may be described by a resource grid with NRBUL NSCRB subcarriers by NsymbUL Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbols. NRBUL represents the number of uplink RBs and NscRB represents the number of subcarriers per RB. NsymbUL represents the number of SC-FDMA symbols in the uplink slot.
A Resource Element (RE) is a resource unit indicated by index (a, b) in the downlink and uplink slots, occupying one subcarrier by one OFDM or SC-FDMA symbol. Here, a denotes a frequency index and b denotes a time index.
FIG. 5 illustrates an example of a downlink subframe structure. Referring to FIG. 5, the first three OFDM symbols of a first slot form a control region allocated to control channels, and the other OFDM symbols of the first slot form a data region allocated to a Physical Downlink Shared CHannel (PDSCH) in a subframe. In 3GPP LTE, the downlink control channels include, for example, a Physical Control Format Indicator CHannel (PCFICH), a Physical Downlink Control CHannel (PDCCH), and a Physical Hybrid Automatic Repeat reQuest (ARQ) Indicator CHannel (PHICH).
The PCFICH, which is transmitted in the first OFDM symbol of a subframe, carries information about the number of OFDM symbols used for the control channels of the subframe. The PHICH delivers a Hybrid ARQ (HARQ) ACKnowledgment/Negative ACKnowledgment (ACK/NACK) signal as a response for an uplink transmission. The PDCCH delivers control information called Downlink Control Information (DCI) which includes downlink or uplink scheduling information or information about an uplink transmit power control command for a user group. Specifically, the PDCCH may carry transport format information, a resource assignment of a Downlink Shared CHannel (DL-SCH), paging information on a Paging CHannel (PCH), system information on the DL-SCH, a resource assignment of an upper-layer control message such as a random access response transmitted on a PDSCH, a set of transmit power control commands for individual UEs of a UE group, and Voice over Internet Protocol (VoIP) activation information. A plurality of PDCCHs may be transmitted in the control region. A UE may monitor the plurality of PDCCHs. A PDCCH is transmitted in a set of one or more consecutive Control Channel Elements (CCEs). The CCEs are logical allocation units used to provide a coding rate to the PDCCH based on a radio channel state. A CCE is a plurality of RE groups. The format of the PDCCH and the number of bits available to the PDCCH are determined according to the correlation between the number of CCEs and a coding rate that the CCEs provide. A BS determines the format of the PDCCH based on DCI transmitted to a UE on the PDCCH and attaches a Cyclic Redundancy Check (CRC) to the control information.
The CRC is masked with an Identifier (ID) specific to the usage of the PDCCH or the user (a Radio Network Temporary Identifier (RNTI)). If the PDCCH is destined for a particular UE, the CRC may be masked with an ID specific to the UE (e.g. a Cell-RNTI (C-RNTI)). If the PDCCH is used for a paging message, the CRC may be masked with a paging indicator ID (e.g. a Paging-RNTI (P-RNTI)). If the PDCCH is used to carry system information, particularly System Information Blocks (SIBs), the CRC may be masked with a system information ID and a System Information-RNTI (an SI-RNTI). To indicate a random access response to a random access preamble received from a UE, the CRC may be masked with a Random Access-RNTI (a RA-RNTI).
FIG. 6 illustrates an uplink subframe structure. Referring to FIG. 6, an uplink subframe may be divided into a control region and a data region in the frequency domain. The control region is allocated to Physical Uplink Control CHannels (PUCCHs) for carrying uplink control information. The data region is allocated to a Physical Uplink Shared CHannel (PUSCH) for transmitting data. To maintain a single carrier property, a UE does not transmit a PUCCH and a PUSCH simultaneously. A pair of RBs are allocated to a PUCCH for a UE in a subframe. The RBs respectively occupy different subcarriers in two slots, with frequency hopping at the boundary between the slots.
Definition of MIMO
The term "MIMO" is short for Multiple Input Multiple Output. Beyond conventional schemes using a single Transmit (Tx) antenna and a single Reception (Rx) antenna, MIMO uses a plurality of Tx antennas and a plurality of Rx antennas to thereby increase the transmission and reception efficiency of data. With the use of multiple antennas at a transmitter or a receiver, MIMO seeks to increase capacity or improve performance in a wireless communication system. The term "MIMO" is interchangeable with "multiple antenna".
The MIMO technology does not depend on a single antenna path to receive an entire message. Rather, it completes the message by combining data fragments received through a plurality of antennas. Because MIMO may increase data rate within a certain area or extend system coverage at a given data rate, it is considered as a promising future-generation mobile communication technology that may find its use in a wide range including mobile terminals, relays, etc. With the growth of data communication, MIMO is attracting attention as a future-generation technology that may overcome a limit on transmission capacity that is almost reached due to the increased data communication.
MIMO System Model
FIG. 7 illustrates the configuration of a typical MIMO communication system. Referring to FIG. 7, a simultaneous increase in the number of Tx antennas of a transmitter to NT and in the number of Rx antennas of a receiver to NR increases a theoretical channel transmission capacity in proportion to the number of antennas, compared to use of a plurality of antennas at only one of the transmitter and the receiver. Therefore, transmission rate and frequency efficiency are remarkably increased. Given a maximum transmission rate Ro that may be achieved in case of a single antenna, the increase of channel transmission capacity may increase the transmission rate, in theory, to the product of Ro and Ri in case of multiple antennas. Ri is a transmission rate increase rate.Ri=min(NT,NR)  [Equation 1]
For instance, a MIMO communication system with four Tx antennas and four Rx antennas may achieve a four-fold increase in transmission rate theoretically, relative to a single-antenna system. Since the theoretical capacity increase of the MIMO system was proved in the middle 1990's, many techniques have been actively studied to increase data rate in real implementation. Some of the techniques have already been reflected in various wireless communication standards for 3rd Generation (3G) mobile communications, future-generation Wireless Local Area Network (WLAN), etc.
Concerning the research trend of MIMO, active studies are underway in many respects of MIMO, inclusive of studies of information theories related to calculation of multi-antenna communication capacity in diverse channel environments and multiple access environments, studies of measuring MIMO radio channels and MIMO modeling, studies of time-space signal processing techniques to increase transmission reliability and transmission rate, etc.
To describe a communication scheme in a MIMO system in detail, the following mathematical model may be used. It is assumed that there are NT Tx antennas and NR Rx antennas as illustrated in FIG. 7. Regarding a transmission signal, up to NT pieces of information can be transmitted through the NT Tx antennas, as expressed as the following vector.s=└s1,s2, . . . ,sNT┘T  [Equation 2]
A different transmit power may be applied to each piece of transmission information s1, s2, . . . sNT. Let the transmit power levels of the transmission information be denoted by P1, P2, . . . , PNT, respectively. Then the power-controlled transmission information ŝ may be given as [Equation 3].ŝ=[ŝ1,ŝ2, . . . ,ŝNT]T=[P1s1,P2s2, . . . ,PNTsNT]T  [Equation 3]
ŝ may be expressed as a diagonal matrix P of transmit power.
                              s          ^                =                                            [                                                                                P                      1                                                                                P                      2                                                                                ⋱                                                                                P                                              N                        T                                                                                ]                                                  [                                                                                s                      1                                                                                s                      2                                                                                ⋮                                                                                s                                              N                        T                                                                                ]                                =          Ps                                    [                  Equation                                                              4                ]
Meanwhile, actual NT transmitted signals x1, x2, . . . , xNT may be configured by applying a weight matrix W to the power-controlled information vector ŝ. The weight matrix W functions to appropriately distribute the transmission information to the Tx antennas according to transmission channel statuses, etc. These transmitted signals x1, x2, . . . , xNT are represented as a vector X, which may be determined as
                                                                        x                =                                  [                                                                                x                          1                                                                                x                          2                                                                                ⋮                                                                                x                          i                                                                                ⋮                                                                                x                                                      N                            T                                                                                ]                                                                                =                                                      [                                                                                w                            11                                                                                w                            12                                                                                ⋯                                                                                w                                                          1                                                                                N                                T                                                                                w                            21                                                                                w                            22                                                                                ⋯                                                                                w                                                          2                                                                                N                                T                                                                                ⋮                                                                                ⋱                                                                                w                                                          i                                                                                1                                                                                w                                                          i                                                                                2                                                                                ⋯                                                                                w                                                          iN                              T                                                                                ⋮                                                                                ⋱                                                                                w                                                                                N                                T                                                                                1                                                                                w                                                                                N                                T                                                                                2                                                                                ⋯                                                                                w                                                                                N                                T                                                                                N                                T                                                                                ]                                                                          [                                                                                s                              ^                                                        1                                                                                s                              ^                                                        2                                                                                ⋮                                                                                s                              ^                                                        j                                                                                ⋮                                                                                s                              ^                                                                                N                              T                                                                                ]                                                                                =                                  W                                                        s                    ^                                                                                =                WPs                                                                                [                  Equation                                                              5                ]
Wij denotes a weight for a jth piece of information transmitted through an ith Tx antenna. W is also referred to as a precoding matrix.
Given NR Rx antennas, signals received at the Rx antennas, y1, y2, . . . yNR R may be represented as the following vector.y=[y1,y2, . . . ,yNR]T  [Equation 6]
When channels are modeled in the MIMO communication system, they may be distinguished according to the indexes of Tx and Rx antennas and the channel between a jth Tx antenna and an ith Rx antenna may be represented as hij. It is to be noted herein that the index of the Rx antenna precedes that of the Tx antenna in hij.
The channels may be represented as vectors and a matrix by grouping them. The vector representation of channels may be carried out in the following manner.
FIG. 8 illustrates channels from NT Tx antennas to an ith Rx antenna.
Referring to FIG. 8, the channels from the NT Tx antennas to the ith Rx antenna may be expressed as [Equation 7].hiT=└hi1,hi2, . . . ,hiNT┘  [Equation 7]
Also, all channels from NT Tx antennas to NR Rx antennas may be expressed as the following matrix.
                    H        =                              [                                                                                h                    1                    T                                                                                h                    2                    T                                                                                ⋮                                                                                h                    t                    T                                                                                ⋮                                                                                h                                          N                      R                                        T                                                                        ]                    =                      [                                                                                h                    11                                                                                h                    12                                                                    ⋯                                                                      h                                          1                                                                    N                        T                                                                                h                    21                                                                                h                    22                                                                    ⋯                                                                      h                                          2                                                                    N                        T                                                                                ⋮                                                                                ⋱                                                                                h                                          i                                                                                1                                                                                h                                          i                                                                                2                                                                                ⋯                                                                      h                                          iN                      T                                                                                ⋮                                                                                ⋱                                                                                h                                                                  N                        R                                                                  1                                                                                h                                                                  N                        R                                                                  2                                                                                ⋯                                                                      h                                                                  N                        R                                                                                N                        T                                                                                ]                                              [                  Equation                                                              8                ]
Actual channels experience the above channel matrix H and then are added with Additive White Gaussian Noise (AWGN). The AWGN n1, n2, . . . , nNR added to the NR Rx antennas is given as the following vector.n=[n1,n2, . . . ,nNR]T  [Equation 9]
From the above modeled equations, the received signal is given as
                                                                        y                =                                  [                                                                                y                          1                                                                                y                          2                                                                                ⋮                                                                                y                          i                                                                                ⋮                                                                                y                                                      N                            R                                                                                ]                                                                                =                                                                            [                                                                                h                              11                                                                                h                              12                                                                                ⋯                                                                                h                                                              1                                                                                N                                  T                                                                                h                              21                                                                                h                                22                                                                                ⋯                                                                                h                                                              2                                                                                N                                  T                                                                                ⋮                                                                                ⋱                                                                                h                                                              i                                                                                1                                                                                h                                                              i                                                                                2                                                                                ⋯                                                                                h                                                                  iN                                  T                                                                                ⋮                                                                                ⋱                                                                                h                                                                                N                                  R                                                                                1                                                                                h                                                                                N                                  R                                                                                2                                                                                ⋯                                                                                h                                                                                N                                  R                                                                                N                                  T                                                                                ]                                                                                [                                                                                x                              1                                                                                x                              2                                                                                ⋮                                                                                x                              j                                                                                ⋮                                                                                x                                                              N                                T                                                                                ]                                                        +                                      [                                                                                n                            1                                                                                n                            2                                                                                ⋮                                                                                n                            i                                                                                ⋮                                                                                n                                                          N                              R                                                                                ]                                                                                =                                  Hx                  +                  n                                                                                [                  Equation                                                              10                ]
Meanwhile, the numbers of rows and columns of the channel matrix H representing a channel status are determined according to the number of Tx antennas and the number of Rx antennas, respectively. That is, the number of rows of the channel matrix H is equal to that of Tx antennas, NT and the number of columns of the channel matrix H is equal to that of Rx antennas, NR. Thus the channel matrix H may be expressed as an NR∴NT matrix. In general, the rank of a matrix is determined to be the smaller between the number of independent rows and the number of independent columns in the matrix. Accordingly, the rank of the matrix is not larger than the number of rows or columns. For example, the rank of the channel matrix H, rank(H) is limited as follows.rank(H)≦min(NT,NR)  [Equation 11]
Reference Signals (RSs)
In a mobile communication system, a packet is transmitted on a radio channel. In view of the nature of the radio channel, the packet may be distorted during the transmission. To receive the signal successfully, the receiver should compensate for the distortion in the received signal using channel information. Generally, to enable the receiver to acquire the channel information, the transmitter transmits a signal known to both the transmitter and the receiver and the receiver acquires knowledge of channel information based on the distortion of the signal received on the radio channel. This signal is called a pilot signal or an RS.
According to the purposes that they serve, RSs are categorized into four types as listed in Table 1, Channel Quality Indicator-Common Reference Signal (CQI-CRS), Demodulation-Common Reference Signal (DM-CRS), Non-precoded Demodulation-Dedicated Reference Signal (NDM-DRS), and Precoded Demodulation-Dedicated Reference Signal (PDM-DRS).
TABLE 1RS TypesNotesCQI-CRSA common reference signal used for channel measurement.The UE determines a CQI, a Precoding Matrix Indicator (PMI), and a Rank Indicator (RI) based on CQI-CRSs. Thus, preferably, CQI-CRSs are uniformly distributed across a total frequency band.DM-CRSAlthough a DM-CRS is a common reference signal used fordemodulation, it can be also used for channel measurement.Because a plurality of UEs use DM-CRSs for channel measurement, a precoding scheme for a specific UE cannot be applied to the DM-CRSs. Thus, when a transmitter precodes a Physical Downlink Shared CHannel (PDSCH), it needs to signal a used codebook on a Physical Downlink Control CHannel (PDCCH) to a receiver.NDM-DRSA non-precoded dedicated reference signal used fordemodulation.PDM-DRSA precoded dedicated reference signal used for modulation.The same precoding scheme is applied to the PDM-DRS and the PDSCH. Thus there is no need for signaling a used codebook on the PDCCH.
In case of data transmission and reception through multiple antennas, knowledge of channel states between Tx antennas and Rx antennas is required for successful signal reception. Accordingly, an RS should exist for each Tx antenna.
FIG. 9 illustrates a downlink RS allocation structure in case of a normal Cyclic Prefix (CP) in a 3GPP LTE system, and FIG. 10 illustrates a downlink RS allocation structure in case of an extended CP in the 3GPP LTE system. The downlink RS allocation structures illustrated in FIGS. 9 and 10 are for the current 3GPP LTE system.
Referring to FIGS. 9 and 10, the horizontal axis represents time and the vertical axis represents frequency in an RB. One subframe includes two slots. Each slot has seven OFDM symbols when the normal CP is used as illustrated in FIG. 9, whereas each slot includes six OFDM symbols when the extended CP is used as illustrated in FIG. 10. The extended CP is used generally under a long-delay environment. The RS allocation structures illustrated in FIGS. 9 and 10 are designed for four Tx antennas in a BS. Reference characters 0, 1, 2 and 3 denote CRSs for first to fourth antenna ports, antenna port 0 to antenna port 3 , respectively, and reference character D denote DRSs.
As noted from FIGS. 9 and 10, in order to distinguish different antennas of a cell from one another, if an antenna port transmits an RS at an RE, the other antenna ports transmit no signals at the RE. Because channel estimation is performed using RSs, this scheme minimizes interference between antenna ports. When cell-specific RSs are used, the subcarrier spacing between RSs in a symbol is 6 and thus a cell-specific frequency shift value may range from 0 to 5. To avoid the same RS positions between cells, each cell determines RS positions using its cell-specific frequency shift value, with the aim to improve channel estimation performance by randomization of interference caused by RSs transmitted from other cells.
In the RS allocation structures illustrated in FIGS. 9 and 10, RSs are mapped to RBs according to the following rules described as [Equation 12] to [Equation 15]. Specifically, [Equation 12] and [Equation 13] describe the rule of mapping CRSs to RBs, and [Equation 14] and [Equation 15] describe the rule of mapping DRSs to RBs.
                              k          =                                    6                            m                        +                                          (                                  v                  +                                      v                    shift                                                  )                                          mod                                                                                6                                                                                l          =                      {                                                                                0                          ,                                                                                N                              symb                              DL                                                        -                            3                                                                                if                                                                                p                                                    ∈                                                      {                                                          0                              ,                              1                                                        }                                                                                1                                                                                if                                                                                p                                                    ∈                                                      {                                                          2                              ,                              3                                                        }                                                                                m                                =                0                            ,              1              ,              …                                                                        ,                                                                    2                    ·                                          N                      RB                      DL                                                        -                                      1                                                                                m                      ′                                                                      =                                                      m                    +                                          N                      RB                                              max                        ,                        DL                                                              -                                                                  N                        RB                        DL                                                                                v                                                        =                                      {                                                                                0                                                                                if                                                                                p                                                        =                                                                                0                                                                                and                                                                                l                                                            =                              0                                                                                3                                                                                if                                                                                p                                                        =                                                                                0                                                                                and                                                                                l                                                            ≠                              0                                                                                3                                                                                if                                                                                p                                                        =                                                                                1                                                                                and                                                                                l                                                            =                              0                                                                                0                                                                                if                                                                                p                                                        =                                                                                1                                                                                and                                                                                l                                                            ≠                              0                                                                                3                                                                                (                                                                                n                                  s                                                                                mod                                                                                2                                                            )                                                                                if                                                                                p                                                        =                            2                                                                                3                            +                                                          3                                                                                (                                                                                n                                    s                                                                                mod                                                                                2                                                                )                                                                                if                                                                                p                                                        =                            3                                                                                [                  Equation                                                              12                ]                                          v          shift                =                              N            ID            cell                                                                        mod                                                              6                                    [                  Equation                                                              13                ]                                          normal                                                              CP                                                                    k          =                                                    (                                  k                  ′                                )                                          mod                                                                                N                sc                RB                                      +                                          N                sc                RB                            ·                              n                PRB                                                                                k          ′                =                  {                                                                                4                                                                          m                          ′                                                                    +                                              v                        shift                                                                                if                                                                                l                                            ∈                                              {                                                  2                          ,                          3                                                }                                                                                4                                                                          m                          ′                                                                    +                                                                        (                                                      2                            +                                                          v                              shift                                                                                )                                                                        mod                                                                                4                                                                                if                                                                                l                                            ∈                                              {                                                  5                          ,                          6                                                }                                                                                l                        =                          {                                                                                3                                                                                l                            ′                                                    =                          0                                                                                6                                                                                l                            ′                                                    =                          1                                                                                2                                                                                l                            ′                                                    =                          2                                                                                5                                                                                l                            ′                                                    =                          3                                                                                l                    ′                                                  =                                  {                                                                                0                                ,                                1                                                                                if                                                                                n                                    s                                                                                mod                                                                                2                                                                =                                0                                                                                2                                ,                                3                                                                                if                                                                                n                                    s                                                                                mod                                                                                2                                                                =                                1                                                                                m                          ′                                                                    =                      0                                        ,                    1                    ,                    …                                                                                ,                                                                                3                                                                                N                            RB                            PDSCH                                                                          -                                                  1                                                                                extended                                                                                CP                                                                                k                            =                                                                                (                                                                      k                                    ′                                                                    )                                                                                mod                                                                                N                                  sc                                  RB                                                                                +                                                                                N                                  sc                                  RB                                                                ·                                                                  n                                  PRB                                                                                k                            ′                                                                                =                                              {                                                                                3                                                                                m                                        ′                                                                                +                                                                          v                                      shift                                                                                if                                                                                l                                                                        =                                    4                                                                                3                                                                                m                                        ′                                                                                +                                                                                (                                                                                2                                          +                                                                                v                                            shift                                                                                )                                                                                mod                                                                                3                                                                                if                                                                                l                                                                        =                                    1                                                                                l                                                    =                                                      {                                                                                4                                                                                l                                          ′                                                                                ∈                                                                                {                                                                                0                                            ,                                            2                                                                                }                                                                                1                                                                                l                                          ′                                                                                =                                        1                                                                                l                                  ′                                                                                =                                                              {                                                                                0                                                                                if                                                                                n                                                  s                                                                                mod                                                                                2                                                                                =                                              0                                                                                1                                              ,                                              2                                                                                if                                                                                n                                                  s                                                                                mod                                                                                2                                                                                =                                              1                                                                                m                                        ′                                                                                =                                    0                                                                    ,                                  1                                  ,                                  …                                                                                ,                                                                                4                                                                                N                                        RB                                        PDSCH                                                                                -                                    1                                                                                [                  Equation                                                              14                ]                                          v          shift                =                              N            ID            cell                                                                        mod                                                              3                                    [                  Equation                                                              15                ]
where vshift denotes a frequency shift value, k denotes a subcarrier index, p denotes an antenna port index, NRBDL denotes the number of allocated downlink RBs, ns denotes a slot index, and NIDcell denotes a cell ID.
According to [Equation 13] and [Equation 15], RSs of a cell may be shifted along the frequency axis by a frequency shift value vshift specific to the cell.
CoMP System
It is known that Inter-Cell Interference (ICI) generally degrades the performance of a UE at a cell edge. To minimize the performance degradation, a simple ICI mitigation technique is used, such as UE-specific Fractional Frequency Reuse (FFR) in LTE. However, an LTE-Advanced (LTE-A) system considers a technique for improving the performance of UEs at a cell edge by controlling ICI with coordination among a plurality of BSs. A system that supports one UE in coordination of a plurality of cells is called a Coordinated Multi-Point (CoMP) system in the standardization phase of LTE-A. The CoMP is characterized in that two or more BSs or cells coordinate with one another to improve the communication performance between a BS (cell or sector) and a UE in a shadowing area.
The CoMP system may increase the throughput of a UE at a cell edge by advanced MIMO transmission in a multi-cell environment. The CoMP system offers the benefits of ICI mitigation in the multi-cell environment and joint data support of multi-cell BSs for a UE. In addition, system performance may be improved since the BSs support one or more UEs (e.g. MS 1 to MS K) in the same radio frequency resources. The BSs may also operate in Space Division Multiple Access (SDMA) based on channel information between the UE and the BSs.
Depending on sharing of data and channel information among cells participating in a CoMP operation (hereinbelow, referred to as CoMP cells), different CoMP schemes are available.
Scheme 1. Both channel information and data are shared among the CoMP cells.
Scheme 2. Only channel information is shared among the CoMP cells.
Scheme 3. Only data is shared among the CoMP cells.
Scheme 4. Neither data nor channel information is shared among the CoMP cells.
Scheme 1 may improve the performance of a UE at a cell edge significantly, as data and channel information are shared among a serving cell and neighbor cells. However, UEs of the CoMP cells should feed back too a large amount of information, which makes it difficult to implement Scheme 1 in a real system. Moreover, the sharing of channel information among the neighbor cells may lead to a long delay.
In Scheme 2, the serving cell receives feedback channel information from UEs at cell edges in neighbor cells and mitigates ICI in a closed loop. While this scheme is considered as offering a gain with a minimal backhaul overhead, the feedback overhead of the UEs may impose a constraint on the system.
Scheme 3 may achieve a gain through open-loop transmission, minimizing system complexity.
Since any particular information for ICI mitigation is not shared among the serving cell and the neighbor cells, Scheme 4 enables simple ICI mitigation and is expected to give a marginal gain to the current LTE system.
Physical Downlink Control Channel (PDCCH)
The PDCCH carries control information about downlink data or uplink data. A UE determines whether there is downlink data directed to the UE or whether the UE is allowed to transmit uplink data, by monitoring the PDCCH. In general, the PDCCH is transmitted in every subframe and the UE determines whether the PDCCH is for the UE by running a random function using its unique ID.
Information transmitted on the PDCCH is divided into control information about downlink data and control information about uplink data. The control information about downlink data includes resource allocation information, modulation and coding information, HARQ process information, a New data Indicator (NDI), Redundancy Version (RV) information, power control information, and additionally, precoding information when MIMO is supported. Different control information about downlink data may be defined according to an operation mode.
The control information about uplink data includes resource allocation information, demodulation-RS resource information, CQI transmission request information, and additionally, precoding information when MIMO is supported.
The LTE-A standardization working body is considering various techniques for further improving the performance of a UE at a cell edge by CoMP-based ICI mitigation. Among them, a joint processing/transmission scheme transmits one or more data streams from a plurality of cells to one UE, sharing one Physical Resource Block (PRB) among the cells. The CoMP cells have their cell-specific frequency shift values for CRSs and DRSs and different numbers of antennas. This means that the CoMP cells have different RS allocation patterns. As a consequence, REs each carrying both data and an RS exist in a PRB allocated to the UE. If CRSs and DRSs reside together in a symbol, it may occur that CRSs overlap with DRSs according to the frequency shift values vshift of the cells. Consequently, system performance is degraded.

Method for transmitting reference signals in a downlink multiple input multiple output system


A method of cleaning thin glass substrates comprises applying a sequence of chemical washing steps as the thin glass substrate is being conveyed in a conveyance direction. In addition, surfaces of the glass substrate may be treated to enhance electrostatic discharge properties of the glass substrates.

Field
This invention generally relates to cleaning of glass articles, and in particular glass substrates used in the manufacture of high performance display panels.
Technical Background
As the line widths of thin film transistors on glass substrates become thinner, technology that removes submicron sized particles effectively so that the transistor is not interrupted by the existence of these contaminants are increasingly in demand. The same can be said for the color filter industry, as contaminants are known to adversely affect black matrix adhesion and resulting RGB pixel integrity. For example, for the color filter industry it is known that black matrix peeling events occur more frequently with narrower line widths. Current industry information indicates the frequency of peeling events are about 2.8% for 19 μm black matrix line widths and 0.3% for 27 um line widths. It is expected these frequencies will increase with decreasing line width. For thin film transistors, it is further expected that this trend will be the same, and removal of increasingly smaller particulate contaminants will become more important. Nevertheless, no industry standard exists for the display glass industry for submicron particle removal, unlike that which exists for the semiconductor industry.


A process for recovering crystals from a slurry which comprises supplying a slurry comprising crystals and a solvent to a rotary vacuum filter and successively conducting filtration under suction, washing, filtration under suction and cleavage of a cake continuously by rotation of a cylindrical filter medium, wherein a vapor having a same composition as that of the solvent is supplied as a blowing gas for cleaving the cake.

1. Field of the Invention
The present invention relates to a process for recovering crystals from a slurry which is used in processes for producing various organic chemical products such as a process for producing terephthalic acid by liquid phase oxidation of para-xylene.
2. Description of the Prior Art
When terephthalic acid is produced by liquid phase oxidation of para-xylene, formed terephthalic acid is crystallized in the mother liquor and a slurry containing crystals of terephthalic acid is formed. Crude terephthalic acid is obtained by recovering the crystals from the slurry. When the obtained crude terephthalic acid is dissolved and purified by treatments for purification such as oxidation treatments and reduction treatments and the purified terephthalic acid is crystallized, a slurry containing crystals can be obtained.
In both treatments of a slurry described above, a rotary vacuum filter (referred to as RVF hereinafter) which run successive filtration under suction, washing, filtration under suction and cleavage of a cake in a batch operation using is most frequently conducted as the process for recovering the crystals from the slurry.
In the operation of RVF, filtration under suction, washing, filtration under suction and cleavage of a cake are conducted successively while a cylindrical filter medium is rotated. However, a continuous operation for a long period of time is difficult in the operation of RVF since the filter medium is clogged during the continuous operation.
The present invention has an object of proposing a process which enables recovery of crystals continuously for a long period of time without clogging of a filter medium when the crystals are recovered from a slurry by using RVF.
As the result of intensive studies by the present inventors on RVF having the above problem, it was found that cleavage of a cake can be facilitated by supplying a vapor having the same composition as that of a solvent as the blowing gas used for cleavage of the cake in the step of cleavage by RVF and the operation of RVF can be continued for a long period of time. The present invention has been completed based on the knowledge.
The present invention provides a process for recovering crystals from a slurry which comprises supplying a slurry comprising crystals and a solvent to a rotary vacuum filter and successively conducting filtration under suction, washing, filtration under suction and cleavage of a cake continuously by rotation of a cylindrical filter medium, wherein a vapor having a same composition as that of the solvent is supplied as a blowing gas for cleaving the cake.

Process for recovering crystals from a slurry

Abstract: The crystals can be continuously recovered for a long period of time without clogging of a filter medium when the crystals are recovered from a slurry by using a rotary vacuum filter.


A timepiece assembly including a balance spring stud fixed to a plate, and a balance spring wound into coils between an inner end fixed to a collet and an outer end fixed to the balance spring stud. The balance spring stud and/or the collet includes a braking mechanism cooperating with a first coil during accelerations by contraction or expansion of the balance spring higher than set values, to modify a resulting rigidity of the balance spring when the first coil is locally coupled to the braking mechanism, arranged on a first inner lip and a second outer lip included in the balance spring stud and/or in the collet, which includes a first inner lip and a second outer lip each including the braking mechanism.

In mechanical watches, regulating members, in particular escapements have to satisfy several "safety" criteria. One of the safety devices, the anti-trip system, is designed to prevent the angular extension of the balance beyond a normal angle of rotation.
The technical problem is to devise a safety mechanism, particularly an anti-trip system, which limits the angle of pivoting of a balance during excessive accelerations, in particular in the event of shocks, notably for a detent escapement. The anti-trip mechanism must be capable of acting in both directions of pivoting of the balance, i.e. both during extension and contraction of the balance spring.
One solution consists in changing the geometry of the balance spring by causing the lugs of consecutive coils to cooperate in abutment, so as to render some coils inactive and thus to modify the rigidity of the balance spring and its response to impulses. A mechanism of this type, capable of limiting the angular travel of the balance in both directions of pivoting is known from EP Patent No 2 434 353 A1 in the name of MONTRES BREGUET SA, which discloses an anti-trip balance spring wherein notches pertaining to consecutive coils cooperate with each other, both during the contraction and the expansion of the balance spring.
US Patent Application No 2009/116343A1 in the name of LEVINGSTON GIDEON describes a balance spring comprising, on the outer coil thereof, a balance spring stud including two lips which can enter into contact with the balance spring during extensions or contractions which are higher than normal, and thereby modify the active length thereof.
EP Patent Application No 1857891A1 in the name of PATEK PHILIPPE describes a one-piece balance spring-collet assembly, the outer contour of the collet comprising at least one stop member with which the balance spring cooperates in abutment in the event of a shock before exceeding the elastic limit of the inner coil.
EP Patent Application No 1818736A1 in the name of the SWATCH GROUP R&D describes a shock absorber collet whose asymmetrical contour follows the inner coil of the balance spring at a substantially constant distance, said contour being able to take the form of a curve provided with discrete bearing points.
U.S. Pat. No. 3,041,819A in the name of ENSIGN, GEORGE describes a sprung balance, wherein the arm of the balance bears a pin provided with a balanced strip, said strip being arranged, according to the angular orientation thereof relative to the arm, to exert a braking force to prevent tripping. In a variant, the outer coil of the balance spring bears a unit capable of interfering with a pin carried by an arm of the balance.
It is an object of the present invention to improve safety, while only very slightly disturbing the inertia of the balance, by limiting the angular travel thereof in both directions of rotation.