A calibrating device for a balance including a load receiving unit for loads to be weighed, a load measuring unit and a lever mechanism serving for the force transmission between the load receiving unit and the load measuring unit, wherein the lever mechanism is coupled to the load receiving unit through a coupling area on an input side and to the load measuring unit through a coupling area at an output side, and wherein the lever mechanism further includes an additional coupling area, separate from the coupling areas on the input and output sides, for releasably coupling a calibrating force which is uncoupled during the normal weighing operation. The balance further includes a parallelogram guide means with two parallel guide members whose first ends are connected to each other through a deflectable member which is guided so as to be movable parallel to the direction of the calibrating force and which serves for the releasable coupling of the calibrating force, and whose second ends are connected to each other through a stationary member, wherein the coupling area serving for the calibration is connected to the deflectable member.

1. Field of the Invention
The present invention relates to a calibrating device for a balance including a load receiving unit for loads to be weighed, a load measuring unit and a lever mechanism serving for the force transmission between the load receiving unit and the load measuring unit, wherein the lever mechanism is coupled to the load receiving unit through a coupling area on an input side and to the load measuring unit through a coupling area at an output side, and wherein the lever mechanism further includes an additional coupling area, separate from the coupling areas on the input and output sides, for releasably coupling a calibrating force which is uncoupled during the normal weighing operation.
2. Description of the Related Art
In a calibrating device of the above-described type known from DE 26 09 560 A1, an approximately V-shaped receiving means for a calibrating weight is provided in a lever serving for the stepping down of the force between the load receiving unit and the load measuring unit. For carrying out the calibration, a calibrating weight is placed in the interior of the balance in the receiving means, wherein the calibrating weight is uncoupled from the lever during the normal weighing operation. In order to ensure a calibration of the balance which is as accurate as possible, the receiving means is arranged over the entire weighing area of the balance with a relatively small calibrating weight on the lever in such a way that the force of the calibrating weight acts fully on the load measuring unit, i.e., without stepping down of the force.
For utilizing the absolute accuracy of a balance achievable as a result of resolution, which may be 0.1 g or even higher when using a 32 kg weighing cell, it is necessary when using the known calibrating device to place the calibrating weight, in longitudinal direction of the lever as well as in a direction perpendicular to the longitudinal direction, in the receiving means with a positional accuracy in the order of magnitude of 10.sup.-3 mm on the longitudinal axis of the lever. For ensuring such a positional accuracy, an extremely complex mechanism is required for releasably coupling the calibrating weight. If the calibrating weight is coupled with less accuracy, the absolute accuracy of the balance determined by the resolution cannot be realized.


A communication system is described in which mobile telephones that are members of closed subscriber groups associated with home base stations are able to roam between neighbouring home node base stations in a manner that reduces load on the core network.

Under the 3GPP standards, a NodeB (or an eNB in LTE) is the base station via which mobile devices connect to the core network. Recently the 3GPP standards body has adopted an official architecture and started work on a new standard for home base stations (HNB). Where the home base station is operating in accordance with the (Long Term Evolution) LTE standards, the HNB is sometimes referred to as a HeNB. A similar architecture will also be applied in the WiMAX network. In this case, the home base station is commonly referred to as a femto cell. For simplicity, the present application will use the term HNB to refer to any such home base station and will use the term NodeB generically to refer to other base stations (such as the base station for the macro cell in which a HNB operates). One or more HNBs will provide radio coverage (for example, 3G/4G/WiMAX) within the home and will connect to the core network via one or more suitable public networks (for example via an ADSL link to the Internet) and in the case of the 3GPP standards, via an HNB gateway (HNB-GW) which will aggregate traffic from the one or more HNBs.
An HNB may be configured to operate using one of a plurality of access modes, namely: 'closed' in which the HNB operates as a closed subscriber group (CSG) cell; 'hybrid' in which the HNB operates as a CSG cell where at the same time, non-members are allowed access; and 'open' in which the HNB operates as a normal (non-CSG) cell.
A mobile device that is a member of multiple CSGs may relocate, following successful access control, from a first home base station that is a member of a first CSG to a second home base station that is a member of a second, different, CSG.

Communication system including a gateway device and method thereof


A capacitive touch display panel including a display panel and a capacitive touch device is provided. The capacitive touch device is disposed on a display surface of the display panel. The capacitive touch device includes at least one opaque bridge line and at least one low reflection pattern layer. The opaque bridge line has a first linewidth and two first main borders. The low reflection pattern layer is disposed on a side of the opaque bridge that is opposite to the display panel. The low reflection pattern layer has a second linewidth and two second main borders. The low reflection pattern layer overlaps the opaque bridge line in a vertical projection direction. The first line width is substantially equal to the second line width, and the first main borders are substantial aligned to the second main borders. A capacitive touch panel and a manufacturing method thereof are provided, too.

Field of the Application
The invention relates to a touch display panel, a touch panel and a manufacturing method thereof, and more particularly, to a capacitive touch display panel, a capacitive touch panel and a manufacturing method thereof.
Description of Related Art
Touch panels are roughly grouped into resistive touch panels, capacitive touch panels, optical touch panels, acoustic wave touch panels and electromagnetic touch panels according to different sensing methods thereof. The capacitive touch panels having advantages of fast response speed, favorable reliability, and durability have been extensively in electronic devices.
In general, the capacitive touch panel includes a plurality of first sensing series extending along a first direction and a plurality of second sensing series extending along a second direction. Wherein, each of the first sensing series is formed by connecting a plurality first sensing pads and first bridge lines in series, and each of the second sensing series is formed by connecting a plurality of second sensing pads and second bridge lines in series. Metal having advantages of favorable conductivity and low impedance is a commonly used material of the bridge lines. However, since the metal has greater reflectivity, it is likely to reflect ambient light and generate bright spots or bright lines, and thus a user is very easy to see bright spots or bright lines at whereby the bridge lines are located, thereby influencing the user's visual experience and lowering the user's willingness to use. Therefore, how to accurately reducing bright spots or bright lines at whereby the bridge lines are located without lowering a display aperture ratio around the bridge lines has become a prominent task for the industries.

Capacitive touch display panel, capacitive touch panel and manufacturing method thereof


An arrangement for guiding at least one movable furniture part includes a guide rail to be mounted on the fixed furniture part, a guide device to be coupled to the movable furniture part, and a preferably substantially cylindrical, load-transmitting rolling body. The guide rail has a guide track, on which the load-transmitting rolling body is mounted in a movable manner. The guide track has a parking position for the load-transmitting rolling body, and the parking position corresponds to an end position of the movable furniture part relative to the fixed furniture part. The load-transmitting rolling body and the guide track are designed such that the guide track can be deformed in this region, a depression being formed in the process, and the load-transmitting rolling body is substantially dimensionally stable.

The invention concerns an arrangement for guiding at least one moveable furniture part, in particular at least one furniture door or at least one drawer, relative to a stationary furniture part. The arrangement includes at least one guide rail to be mounted in particular to the stationary furniture part, and at least one guide device which can be coupled to the at least one moveable furniture part and which has at least one preferably substantially cylindrical load-transmitting rolling body. The at least one guide rail has at least one track on which the at least one load-transmitting rolling body is moveably mounted, the at least one track has at least one parking position for the at least one load-transmitting rolling body and the at least one parking position corresponds to an end position of the at least one moveable furniture part relative to the stationary furniture part. The invention further concerns an article of furniture comprising at least one moveable furniture part, in particular at least one furniture door or a drawer, a stationary furniture part and at least one such arrangement for guiding the at least one moveable furniture part relative to the stationary furniture part.
FIG. 1 shows a combination of a rolling body 106 mounted rotatably about an axis of rotation 133 and a track 107, as is used in the state of the art. In this arrangement, in a parking position 108 of the rolling body 106, flattening can occur in the contact region of the rolling body 106 with the track 107 due to the loading of the rolling body 106. If now the rolling body 106 is moved out of the parking position 108 by rotation about the axis of rotation 133, the flattening 134 firstly moves away from the track 107, in the course of a continued rotary movement it moves to the track 107 again and then comes into contact with same again. The change between the round region of the rolling body 106 and the flattened region 134 on the track 107 gives rise to a rattling noise which is perceived as being troublesome for a user.
To overcome that problem, there are approaches which involve providing the rolling body 106 with a plastic sheath to avoid flattening of the rolling body 106. It is found, however, that the described problem is not overcome thereby but only delayed as the plastic sheath splits sooner or later.

Arrangement for guiding at least one movable furniture part


An optical pickup device includes:                a laser source for emitting, to an optical disk, a laser beam having a wavelength λ1 and a laser beam having a wavelength λ2, which is longer than the wavelength λ1;         a light receiver, for receiving laser beams that are reflected by the optical disk;        a beam splitter, for directing, to the light receiver, the laser beams reflected by the optical disk; and        an astigmatism generation element, located between the beam splitter and the light receiver, for generating the laser beams to be used for focusing control, by designating as the front of the light receiver a focal point on one of the intersecting cross sections that include the light axes of the laser beams, and by designating as the rear of the light receiver, a focal point on the other cross section,        wherein the astigmatism generation element is an optical element, which is like a Fresnel lens, whose step depth is substantially a natural number times either the wavelength λ1 or the wavelength λ2.

1. Field of the Invention
The present invention relates to an optical pickup device and an optical disk drive that are mounted on an electronic apparatus, such as a personal computer or a notebook computer.
2. Description of the Related Art
Conventionally, the downsizing of electronic apparatuses, such as personal computers and notebook computers, has been expedited, and accordingly, the downsizing of optical pickup devices and optical disk drives to be mounted on these apparatuses has also been advanced.
FIG. 18 is a diagram showing the arrangement of the essential portion of the optical system of a conventional optical pickup device. A laser source 101 emits, toward an optical disk 104, a laser beam, for a DVD, having a wavelength λ1 of about 650 nm and a laser beam, for a CD, having a wavelength λ2 of about 780 nm. A prism 102 is formed of optical glass, for example, and internally includes a slope on which a beam splitter 103 is formed. The beam splitter 103 is a polarizing separation film, for which one property is that while a laser beam emitted by the laser source 101 is permitted to pass and continues on to the beam disk 104, a laser beam that is reflected by the optical disk 104 is reflected. The optical disk 104 is a DVD or a CD. A detection lens 105 is an astigmatism generation element having the shape of a so-called columnar lens or a cylindrical lens, and a focal length that differs for two intersecting cross sections that include light axes. A light receiver 106 has a photo detector 107 for receiving light reflected by the optical disk 104.
The laser beam having the wavelength λ1 and the laser beam having the wavelength λ2, both emitted by the laser source 101, pass through the beam splitter 103 and strike the optical disk 104. The laser beams reflected by the optical disk 104 are reflected by the beam splitter 103, and the reflected beams are transmitted to the detection lens 105 and then enter the light receiver 106.
FIG. 19A is an explanatory diagram for a conventional detection lens, FIG. 19B is a diagram showing the state of a spot when an optical disk is located nearby, and FIG. 19C is a diagram showing the state of a spot when an optical disk is located at a distance. In FIG. 19A, the arrangement of detection lens 105 is such that a cross section in the vertical direction is focused before beams enter the light receiver 106, and a cross section in the horizontal direction is focused after the beams enter the light receiver 106. That is, the light receiver 106 is centrally located, between the two focuses, and the shape of a spot 108 on the light receiver 106 is almost circular. When, as shown in FIG. 19B, the optical disk 104 is located near the optical pickup device, the spot 108 formed by laser beams on the light receiver 106 is extended horizontally. On the other hand, when, as shown in FIG. 19C, the optical disk 104 is located at a distance from the optical pickup device, the spot 108 formed by laser beams on the light receiver 106 is extended vertically. When the photo detectors A to D 107 are arranged in a cross shape and calculate a focus error signal FES=(A+C)−(B+D), a focus control signal can be obtained. That is, when the optical disk 104 is located nearby, the focus error signal FES>0 is obtained, and when the optical disk 104 is located at a distance, the focus error signal FES<0 is obtained, which together enable the location of the optical disk 104 to be identified.
According to (patent document 1), an optical member is additionally provided between the beam splitter 103 and the detection lens 105 in order to reduce the intensity at the center portion of the light reflected by the optical disk 104. As a result, the possibility is reduced that a track crossing signal will occur that enters a focus control signal.
Patent Document 1: JP-A-6-309687
The thickness of the detection lens, however, must be reduced in order to further provide for the downsizing of the optical pickup device and the optical disk drive. But when the detection lens is thinned, a satisfactory difference is hard to obtain between the focal lengths of the two intersecting cross sections that include the light axes, and the sensitivity of a focus control signal is reduced.

Optical pickup device and optical disk drive


An image forming apparatus is disclosed that can specify the cause and the part of an electrical failure with an inexpensive configuration and facilitate the maintenance by a user or an administrator. Power is supplied to function units in the image forming apparatus and a value is detected by a power detection unit. A state of the image forming apparatus is specified by a first control unit that can determine, based on the specified state and the detected value, whether or not there is an electrical failure. If there is a determined electrical failure, the power is supplied separately to the function units so that the first control unit can specify an electrically failed part based on a state of the image forming apparatus estimated at the separate supply and the detected value, and can notify a user or an administrator of the specified failed part.

1. Field of the Invention
The present invention relates to an image forming apparatus, a controlling method therefor, and a storage medium, and more particularly, to a power control technique when an abnormality occurs in an image forming apparatus.
2. Description of the Related Art
Japanese Laid-Open Patent Publication (Kokai) No. 2002-232625 discloses an image forming apparatus including: a unit configured to detect a communication error of a command or the like between units in the apparatus; and a unit configured to notify a user of content of the error, so as to enable the user to handle the communication error at the occurrence of the communication error.
In conventional image forming apparatuses, electrification of a part with a problem is cut off, or supply of main power is terminated, when an abnormality occurs in the power supply. Particularly, disclosed is a method of handling an abnormality according to the type of the abnormality, such as a degree of importance thereof and a degree of urgency thereof, from a serious abnormality in which the power needs to be immediately turned off to a minor abnormality in which electrification of part of the electrical circuit needs to be temporarily cut off (see Japanese Laid-Open Patent Publication (Kokai) No. 2012-123242).
However, there is a problem in Japanese Laid-Open Patent Publication (Kokai) No. 2002-232625 that whether the communication error between units in the apparatus is caused by an electrical failure or by a software failure of a processor, such as a CPU, cannot be specified, and further the failed part cannot be specified.
In Japanese Laid-Open Patent Publication (Kokai) No. 2012-123242, each unit, such as a heater circuit for fixing, recording paper transport rollers, a controller substrate, a printer engine substrate, and a scanner substrate, includes a power sensor, and this increases the cost.

Image forming apparatus, controlling method therefor, and storage medium


A roulette gaming machine includes: a roulette wheel on which marks are placed; a lottery unit for drawing a win mark; a bet area display unit for displaying a bet areas formed based on the same marks as the marks placed on the roulette wheel; a selection unit for selecting a bet area displayed on the bet area display unit; a bet unit for betting a game value on the bet area; a history storage unit for storing a lottery results as history data; a search condition selection unit for selecting a search condition concerning the win frequency of each mark; a search unit for searching the history data; and a conditional bet unit for betting a game value on the bet area corresponding to a search result of the search unit.

1. Field of the Invention
This invention relates to a roulette gaming machine for enabling a player to bet based on a game result history, thereby increasing the variety of the game entertainment.
2. Description of the Related Art
A medal game using a medal as a game medium of a slot machine, a roulette game machine, a card game machine, etc., is a game that can be started by a player who purchases or borrow a plurality of medals with a medal lending machine and inputting the medal to the gaming machine. If the player wins the game, a predetermined number of medals are paid out to the player. Therefore, the player who can gain a large number of medals can enjoy a successive game without purchasing or borrowing new medals. Particularly, with a roulette gaming machine, the player bets a medal purchased or borrowed with a medal lending machine on a win-possible number, thereby playing a game.
In a related art, for the player to bet with the roulette gaming machine, a betting board displayed on a monitor display is used, as shown in JP-A-2003-325726. A plurality of numbers (containing also letters) as pattern characters containing the same numbers as the numbers displayed on a wheel are displayed on the betting board like squares. Using the betting board with the numbers arranged like squares thereon, the player predicts the number to bet on and bets a chip on the number.
However, the roulette gaming machine described in JP-A-2003-325726 is a gaming machine for the player to play a game according to a bet method involved in general roulette, and the player determines the mark to bet on by his or her decision. Often, the player uses the past win result in the roulette game as the decision material on determining the mark to bet on. That is, a large number of players make a decision that "the mark has not become a win mark recently and therefore will probably become a win mark in the next game" or that "the mark has often become a win mark recently and therefore will also probably become a win mark in the next game" from the past win result in the roulette game.
However, in the roulette gaming machine described in JP-A-2003-325726, the player can keep track of the game result only under player's eyes.
If the player keeps track of the game result and predicts the mark to bet on based on the winning frequency of the mark, 38 marks exist on the roulette wheel and thus a plurality of marks at the same degree of frequency as the frequency determined by the player can frequently occur. Therefore, in such a case, the player needs to search the betting wheel for the corresponding marks and then bet on each of the marks; the player must perform intricate operation. Usually, the mark mentioned here is assigned any of natural numbers of 0 to 36 (00 may be contained).


Galvannealed steel sheet simultaneously able to achieve excellent workability and high strength and a method of production of the same are provided as an objective, in particular high strength galvannealed steel sheet excellent in workability, comprising high strength steel sheet containing, by mass %, C: 0.05 to 0.15%, Si: 0.3 to 2.0%, Mn: 1.0 to 2.8%, P: 0.03% or less, S: 0.02% or less, Al: 0.005 to 0.5%, and N: 0.0060% or less and a balance of Fe and unavoidable impurities, where, when % C, % Si, and % Mn respectively represent the C, Si, and Mn contents, (% Mn)/(% C)≧12 and (% Si)/(% C)≧4 being satisfied, on the surface of which having a galvannealed layer containing Al: 0.05 to 0.5 mass % and Fe: 5 to 15 mass % and a balance of Zn and unavoidable impurities, said steel sheet satisfying a relationship of tensile strength F (MPa) and elongation L (%) of L≧52−0.035×F.

As coated steel sheet with a good corrosion resistance, there is galvannealed steel sheet. This galvannealed steel sheet is usually produced by degreasing the steel sheet, then preheating it in a nonoxidizing furnace, cleaning the surface, securing the desired quality by annealing it by reduction in a reducing furnace, dipping it in a hot-dip zinc bath, controlling the amount of deposition, then alloying it. This is characterized by excellent corrosion resistance and coating adhesion etc., so is being widely used for automotive and building material applications etc.
In particular, in recent years, in the automobile field, higher strength of coated-steel sheet has been considered necessary for securing the function of protecting the passengers against collisions and for reducing weight so as to improve the fuel efficiency.
To increase the strength of steel sheet without detracting from the workability, it is effective to add elements like Si or Mn and P, but addition of these elements delays the alloying, so compared with mild steel, a higher temperature and longer time are required for alloying. This higher temperature, longer alloying causes the austenite remaining in the steel sheet to transform to pearlite and reduces the workability, so as a result the effects of these added elements is canceled out. For the alloying of Si-containing high strength steel sheet, Japanese Unexamined Patent Publication (Kokai) No. 5-279829 discloses a method of production realizable even by a continuous hot-dip galvanizing line, but the range of the production conditions is described extremely broadly and this is of little use in actual production. Further, the method of production disclosed in Japanese Unexamined Patent Publication (Kokai) No. 11-131145 causes the formation of retained austenite by holding the sheet at a low temperature after coating, but this invites an increase in the facilities, so detracts from the productivity.

High strength galvannealed steel sheet excellent in workability and a method of production of the same


A semiconductor wafer baking apparatus includes a hot plate, a container of which an upper part is open, and a cover that covers the upper part of the container. The cover includes an upper plate, a lower plate and a side wall that form a gas circulating space therebetween. At least one gas inlet is formed in the side wall, a plurality of gas supply holes are formed in a central region of the lower plate, and a skirt on which is formed a gas exhaust unit is coupled to a lower edge of the cover.

1. Field of the Invention
The present invention relates to a semiconductor wafer baking apparatus and, more particularly, to a semiconductor wafer baking apparatus that can maintain uniform temperature over a semiconductor wafer and can improve a purging efficiency during baking.
2. Description of the Related Art
Generally, semiconductor devices are manufactured through processes of ion implanting, thin film deposition, diffusion, photolithography, and etching. Among these processes, photolithography is an essential part of semiconductor manufacture, allowing a desired pattern to be formed. Photolithography involves transferring a pattern from a photo mask to a photo resist (PR) coated on a substrate, using an exposure system, and etching a predetermined pattern into a material film below using the photo resist as an etch mask. In this case, the photo resist is a photo sensitive resin, and the major components of the photo resist are polymer, a solvent, and a sensitizer.
The photolithography process includes a baking process, where the substrate is heated before or after coating with the photo resist. In the baking process, an organic solvent is removed from the photo resist in the form of fumes.
The baking process generally includes four steps. The first is a pre-baking step, in which organic materials or moisture are removed from the surface of the substrate by heating the substrate before coating the photo resist onto the substrate. The second is a soft baking, immediately after coating the photo resist onto the substrate. The third is a post exposure baking, after exposing the photo resist. The last is a hard baking, after developing the photo resist.
An apparatus for performing the baking process generally includes a hot plate that heats a wafer coated with photo resist, and a chamber in which the hot plate is mounted. A purging gas, such as N2 gas, for exhausting fumes from the photo resist during baking, is supplied to the chamber. At this time, the purging gas is one of the factors that causes a temperature gradient in the chamber, which affects the critical dimensions of the semiconductor devices integrated on the wafer. The thermal stability of the baking apparatus is a factor in the baking process, so it is desirable to heat the wafer uniformly.
Therefore, there is a need to develop a baking apparatus that can minimize the effect of the purging gas on a wafer, and can exhaust fumes from the photo resist during baking.


A memory device is proposed which enables to guarantee the operation of MRAM elements being magnetically shielded against a large external magnetic fields without being affected by an internal leakage magnetic field. The MRAM elements 30 which are shielded by magnetic shield layers 33, 34 are placed at an intermediate region 41 avoiding an edge region 43 and a center region 42 of the magnetic shield layers 33, 34 so that the MRAM element is secured to operate normally without being affected by the internal leakage magnetic field avoiding the edge region 43 where the magnetic shield effect is reduced by the exterior magnetic field, and avoiding the central region 42 where the internal leakage magnetic field is large.

The present invention relates to a magnetic memory device constructed as a magnetic random access memory (MRAM) or a so-called non-volatile MRAM (Magnetic Random Access Memory) which is comprised of memory elements made by laminating a magnetization pinned layer in which the orientation of magnetization is fixed and a magnetic layer in which the orientation of magnetization is changeable, or to any magnetic memory device comprising memory elements having a magnetic layer capable of being magnetized.
With a rapid prevalence of information communication equipment, in particular, of personal compact equipment such as portable terminals, a further improvement in performance inclusive of larger scale integration, faster speed, lower power consumption or the like is demanded for their elements such as memories, logics and the like.
In particular, the non-volatile memory is considered to be indispensable in the age of ubiquitous. If a power supply is exhausted or a power trouble occurs, or even if a connection between the server and the network is cut off by any failure, the non-volatile memory can protect important information including personal information. Further, although recent portable equipment is designed to hold unnecessary circuitry blocks in a standby state in order to suppress power consumption as much as possible, if a non-volatile memory that can function both as a high speed work memory and as a large capacity storage memory is realized, losses of the power consumption and the memory can be eliminated. Still further, if a high speed and large capacity non-volatile memory can be realized, an "instant-on" function that can be instantaneously activated upon power-on operation becomes possible.
As the non-volatile memories, there are also cited a flash memory which uses semiconductors, a FRAM (Ferroelectric Random Access Memory) which uses a ferroelectric material, and the like.
However, the flash memory has a drawback that a write speed is low in the order of μ seconds. On the other hand, also in the FRAM, problems are cited that because the number of rewritable frequencies is 1012 to 1014, the endurance thereof is too small to completely replace SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory), and that micro fabrication of a ferroelectric capacitor is not easy.
Drawing attention as a non-volatile memory having no such drawbacks as described above, featuring a high speed, large capacity (large scale integration) and a low power consumption, is a so-called MRAM (Magnetic Random Access Memory), for example, described by Wang et al., in IEEE Trans. Magn. 33 (1997), 4498, which has begun to draw much attention by recent remarkable improvements in the characteristics of TMR (Tunnel Magnetoresistance) materials.
An MRAM is a semiconductor memory which utilizes a magnetoresistance effect based on a spin dependent conducting phenomenon characteristic to a nano-magnetic substance, and is a non-volatile memory capable of retaining information without power supply from external.
Moreover, because of its simple structure, MRAM is easy to integrate into a large scale IC, and because of its recording of information based on spinning of magnetic moments, the number of rewritable frequencies is large, and also its access time is expected to become very fast as reported by R. Scheuerlein et al., in the ISSCC Digest of Technical Papers, pp. 128–129, Feb. 2000, where operability at 100 MHz was already reported.
Such a MRAM will be described more in detail. As illustrated in FIG. 14, a TMR element 10 which constitutes a memory cell in a memory element of MRAM includes a memory layer 2 in which magnetization is relatively easily rotated, and magnetization pinned layers 4, 6, laminated on a support substrate 9.
The magnetization pinned layer has two magnetization pinned layers of a first magnetization pinned layer 4 and a second magnetization pinned layer 6, and a conductive layer 5 is interposed therebetween for antiferromagnetically coupling these magnetic layers. As a memory layer 2 and magnetization pinned layers 4 and 6, a ferromagnetic material made of nickel, iron or cobalt, or an alloy thereof is used. Also, as a material of the conductive layer 5, any of ruthenium, copper, chrome, gold, silver or the like can be used. The second magnetization pinned layer 6 abuts an antiferromagnetic material layer 7. An exchange interaction occurring between these layers causes the second magnetization pinned layer 6 to have a strong unidirectional magnetic anisotropy. As a material of the antiferromagnetic material layer 7, a manganese alloys with such as iron, nickel, platinum, iridium, rhodium, or cobalt or nickel oxides may be used.
Further, between the memory layer 2 as the magnetic layer and the first magnetization pinned layer 4 there is sandwiched a tunnel barrier layer 3 which is an insulating body made of an oxide or nitride of aluminum, magnesium, silicon and the like, and functions to cut off a magnetic coupling between the memory layer 2 and the magnetization pinned layer 4 and also to pass a tunneling current therethrough. These magnetic layers and conductive layers are formed basically by a sputtering method, however, the tunnel barrier layer 3 can be obtained by oxidizing or nitriding a metal film deposited by sputtering. A top coat layer 1, which has a function to prevent mutual diffusion between the TMR element 10 and wiring to be connected thereto, to reduce a contact resistance, and to inhibit oxidization of the memory layer 2, can be made using such a material as Cu, Ta, TiN or the like. An underlayer electrode 8 is for connection with a switching element to be connected in series with the TMR element. This underlayer electrode 8 may serve also as an antiferromagnetic material layer 7.
In the memory cell constructed as described above, although information is read out by detecting changes in a tunneling current by the magnetoresistance effect to be described later, the effect thereof depends on relative orientations of magnetization in the memory layer and the magnetization pinned layer.
FIG. 15 is an enlarged perspective view showing a simplified portion of a general MRAM. Here, although a read-out circuit portion is omitted for simplification, there are included, for example, 9 pieces of memory cells, and mutually intersecting bit lines 11 and writing word lines 12. At each intersection therebetween, a TMR element 10 is disposed. Writing to the TRM element 10 is carried out in such a manner that by passing a current through the bit line 11 and the write word line 12, and by using a synthetic magnetic field resulting from respective magnetic fields generated therefrom, an orientation of magnetization in the memory layer 2 in the TMR element 10 disposed at each intersection of the bit line 11 and the write word line 12 is caused to rotate parallel or anti-parallel relative to that in the magnetization pinned layer.
FIG. 16 schematically illustrates a cross section of a memory cell, in which, for example, an n-type field effect transistor 19 for read out is disposed, comprising a gate insulation film 15, a gate electrode 16, a source region 17 and a drain region 18 which are formed in a p-type well region 14 formed in a p-type silicon semiconductor substrate 13, and above thereof there are disposed a write word line 12, a TMR element 10 and a bit line 11. To the source region 17, a sense line 21 is connected via a source electrode 20. The field effect type transistor 19 functions as a switching element for read-out, and a wiring 22 for reading which is wired out from between the word line 12 and the TMR element 10 is connected to the drain region 18 via a drain electrode 23. By way of example, the transistor 19 may be of any of n-type or p-type field effect transistors, and is not limited thereto, and various types of other switching elements such as diodes, bipolar transistors, MESFET (Metal Semiconductor Field Effect Transistors) and the like can be used.
FIG. 17 shows an equivalent circuit of an MRAM, which has, for example, 6 pieces of memory cells, mutually intersecting bit lines 11 and write word lines 12, and TMR elements 10 provided at each intersection of these write word lines together with a field effect transistor 19 for selection of an element for reading which is connected to the TMR element 10 and to a sense line 21. The sense line 21 which is connected to a sense amplifier 27 detects stored information. By way of example, numeral 24 in the drawing depicts a bidirectional write word line current drive circuit, and 25 depicts a bit line current drive circuit.
FIG. 18 is an asteroid curve showing write conditions to write to the MRAM, and indicates a threshold value for reversing the orientation of magnetization in the memory layer by a magnetic field HEA applied in the directions of the easy axis of magnetization and a magnetic field HHA applied in the directions of the difficult axis of magnetization. If a synthetic magnetic field vector is produced outside this asteroid curve, a reversal of the magnetic field occurs, however a synthetic magnetic field produced inside the asteroid curve does not cause the cell to be reversed from either one of its current bistable state to the other. Further, also in any cells other than at intersections of the word lines and the bit lines both passing through the currents, because a singular magnetic field generated either by the word line or the bit line is applied thereto, if a magnitude thereof exceeds a monodirectional reversal magnetic field Hk, the orientation of magnetization in any cells outside the aforementioned intersections may be reversed. Therefore, it is arranged to permit a selective writing to a selected cell only when the synthetic magnetic field falls in a grey-colored region in the drawing.
As described above, as to the MRAM, it is general that by use of two write lines of the bit line and the word line, and utilizing the asteroid magnetization reversal characteristics, only a designated cell is allowed selectively to write in to be effected by reversal of a magnetic spin. A synthetic magnetic field in a unit memory region is determined by a vector synthesis of a magnetic field applied in the direction of the easy axis of magnetization HEA and a magnetic field applied in the direction of the difficult axis of magnetization HHA. A current passing through the bit line applies a magnetic field in the direction of the easy axis of magnetization HEA to the cell, and a current passing through the word line applies a magnetic field in the direction of the difficult axis of magnetization HHA to the cell.
FIG. 19 illustrates operation of reading from MRAM. Here, a schematic diagram of a layer structure of a TMR element 10 is shown, in which the aforementioned magnetization pinned layer is depicted as a monolayer 26, and parts other than a memory layer 2 and a tunnel barrier layer 3 are omitted for simplification.
That is, as described above, writing of information is carried out by causing a synthetic magnetic field produced at the intersection between the bit lines 11 and the word lines 12 wired in a mesh to reverse the magnetic spin in the cell so as to store the information as "1" or "0". Further, reading of information is carried out by utilizing a TMR effect which makes use of the magnetoresistance effect. Here, the TMR effect refers to such a phenomenon that a value of electrical resistance is changed depending on the orientation of the magnetic spin, and that by detecting a high resistance state if the magnetic spin is oriented anti-parallel (reverse direction) and a low resistance state if the magnetic spin is oriented parallel (same direction), information of "1" and "0" is detected. This reading is carried out by causing a read current (tunneling current) to pass through between the word line 12 and the bit line 11, and reading out an output therefrom in accordance with the aforementioned high resistance or low resistance to the sense line 21 via the field effect transistor 19 for reading.
As described above, although the MRAM is expected as a high speed and large capacity non-volatile memory, because of use of the magnetic material for retention of information, there is such a problem that information is erased or rewritten by the effect of an external magnetic field. This is because that a reversing magnetic field HSW in the directions of the easy axis of magnetization and the difficult axis of magnetization described with reference to FIG. 18 is small in a range of 20 to 200 Oe, though it depends on a material, and a few mA in terms of an electric current (R. H. Koch et al., Phys. Rev. Lett. 84, 5419 (2000), J. Z. Sun et al., 2001 8th Joint Magnetism and Magnetic Material). In addition, because a coercive force (Hc) when writing is in a range of approximately a few Oe to 10 Oe, if an internal leakage magnetic field greater than that resulting from an external magnetic field is applied, it sometimes becomes impossible selectively to write to a designated memory cell.
Therefore, as one step to actual application of the MRAM, it is ardently desired to establish countermeasures against external magnetic fields, that is, an effective magnetic shield structure for shielding the elements from external electromagnetic waves.
An environment in which an MRAM is packaged and used is mainly on a high density packaging substrate, and inside electronics equipment. Although it depends on the types of electronic equipment, by recent developments of high density packaging techniques, there are densely packaged a variety of semiconductor elements, communication elements, a micro-motor and the like on a high density packaging substrate, and also antenna elements, various mechanical parts, power source and the like are densely packaged inside the electronic equipment thereby constructing a unit of equipment.
A capability of a mixed or hybrid packaging as described above is one of the features of an MRAM as a non-volatile memory, however, because of its environment surrounding the MRAM in which various magnetic field components in a broad frequency range including dc, low frequencies to high frequencies are mixed and coexist, it is required, in order to ensure reliability of information retaining in MRAM, to improve the durability thereof against the external magnetic fields by developing a new packaging method and a new shield structure of the MRAM itself.
As to a magnitude of such external magnetic fields, for example, in a magnetic card such as a credit card or a bank cash card, it is specified to have durability against a magnetic field from 500 to 600 Oe. Therefore, in the field of the magnetic card, a magnetic material having a large coercive force such as a Co clad gamma-Fe2O3, Ba ferrite or the like are used in compliance therewith. Also, in the field of prepaid cards, it is necessary to have durability against magnetic fields from 350 to 600 Oe. Because the MRAM element is packaged inside electronic equipment, and is a device expected to be carried on, it needs to have enough durability against strong external magnetic fields equivalent to that of the magnetic cards, and in particular, because of the reason described above, a magnitude of an internal (leakage) magnetic field is required to be suppressed below 20 Oe, or preferably below 10 Oe.
As a magnetic shield structure of MRAM, it is proposed to use an insulating ferrite (MnZn ferrite and NiZn ferrite) layer as a passivation film of an MRAM element so as to provide a magnetic shielding characteristic (refer to U.S. Pat. No. 5,902,690, specification (column 5) and drawings (FIG. 1 & FIG. 3)). It is also proposed to attach a high permeability magnetic body such as Permalloy on the top and bottom of the package so as to provide a magnetic shielding effect and prevent penetration of a magnetic flux into the internal element (refer to U.S. Pat. No. 5,939,772, specification column 2, FIGS. 1, 2). Further, a structure of a shield lid made of a magnetic material such as soft iron or the like for cladding the element is disclosed (refer to Japanese Patent Application Publication No. 2001-250206, right-hand column on page 5, FIG. 6).
In order to prevent penetration of an external magnetic flux into the memory cell of MRAM, it is most important to clad the element with a magnetic material having a high permeability so as to provide a magnetic path thereby allowing no magnetic flux to penetrate any further.
However, when the passivation film of the element is formed from ferrite as disclosed in U.S. Pat. No. 5,902,690, because of a low magnetic saturation in the ferrite itself (for example, 0.2 to 0.5 tesla (T) in general ferrite materials), it is impossible completely to prevent penetration of external magnetic fields. Magnetic saturation in the ferrite itself is approximately 0.2 to 0.35 T in NiZn ferrite, and 0.35 to 0.47 T in MnZn ferrite, however, a magnitude of an external magnetic field penetrating into the MRAM element is as large as several hundreds Oe, thereby only with such a degree of saturation magnetization provided by the ferrite, a permeability becomes almost "1" due to magnetic saturation in the ferrite thereby disabling its function. Further, although a film thickness is not described in U.S. Pat. No. 5,902,690, because a thickness of a normal passivation film is about 0.1 μm or so at most, it is too thin to serve as a magnetic shield layer, thereby any substantial effect cannot be expected. Moreover, in the case if ferrite is to be used as the passivation film, because the ferrite is an oxide magnetic material, when it is deposited by sputtering, an oxygen defect tends to occur, thereby making it difficult to obtain a perfect ferrite to be used as the passivation film.
Further, in U.S. Pat. No. 5,939,772, a structure for sandwiching the package between the upper and the bottom Permalloy layers is disclosed. By use of the Permalloy, a higher shield performance than that of the ferrite passivation film is obtained. However, although the permeability of the Mu metal disclosed in U.S. Pat. No. 5,939,772 is very high to become μi=100,000 or so, the magnetic saturation thereof is very low to be 0.7 to 0.8 T, at which it will easily saturate to an external magnetic field consequently to become μ=1, therefore, there is a problem that in order to obtain a perfect magnetic shielding effect, a thickness of the shield layer must be increased considerably large. Therefore, as the structure for enabling to prevent penetration of magnetic fields of several hundreds Oe, in practice, it is not yet perfect as the magnetic shield layer in view of both drawbacks that the saturation magnetization thereof is too small and that the thickness thereof is too thin.
Still further, in Japanese Patent Application Publication No. 2001-250206, although a magnetic shield structure using soft iron or the like is disclosed, as this covers only the upper portion of the element, it is not perfect as the magnetic shield. Also, the magnetic characteristics thereof are not sufficient because that the saturation magnetization of the soft iron is 1.7 T and the permeability thereof is μi=300 or so. Therefore, even if a magnetic shield is fabricated using the structure disclosed in Japanese Patent Application Publication JP-A Laid-Open No. 2001-250206, it would be very difficult to completely prevent the penetration of external magnetic fields.
The present invention is contemplated to solve the aforementioned problems associated with the prior art, and to provide means for magnetically shielding MRAM elements sufficiently against large external magnetic fields, and also to guarantee reliable operation of the MRAM elements in an environment surrounding the MRAM elements which produces various magnetic fields.

Detailed description of the presently preferred embodiments


The present invention relates to the field of biochemistry, more particularly to proteomics, more particularly to protein sequencing, even more particularly to single molecule peptide sequencing. The invention discloses methods for single molecule protein sequencing and/or amino acid identification using cleavage inducing agents which are not specific for one particular amino acid, cleave polypeptides step by step from the N-terminus onwards and provide information on the identity of the cleaved amino acids based on the reaction kinetics.

Technologies for high throughput sequencing of biomolecules (DNA, RNA, protein) are rapidly evolving and are critical for modern science and medicine. In particular, sequencing technologies for DNA has taken giant leaps, now moving from next-generation to third generation approaches acting on single molecule level (e.g. Pacific Biosciences, Oxford Nanopores; Ambardar et al. 2016 Indian J Microbiol 56:394-404). The uniform nature of DNA and the broad panel of available molecular tools has truly pushed the field forward. In contrast, protein/peptide sequencing is lagging behind, and is largely depending on liquid chromatography-mass spectrometry (LC-MS) based technology. Although LC-MS instrumentation has advanced considerably in terms of speed, sensitivity and resolution, operating and maintaining the machinery is highly complex and expensive. Moreover, MS-based proteomics still requires approximately 106 copies of a protein/peptide in order to be detected. Single protein/peptide sequencing is currently not possible, and applications such as single cell proteomics are therefore beyond reach. Moreover, since proteins cannot be amplified in the way that DNA can, single molecule sequencing is conceptually a better match, and would furthermore allow for digital quantification of proteins.
Concepts for next-generation protein sequencing are now germinating, but are facing major challenges. First, there are twenty amino acids to differentiate (as compared to only four nucleotides), and obtaining a single measurable parameter to rigorously identify every amino acid appears unlikely. However, being able to ascribe a certain amino acid category to each sequence position even in a probabilistic manner may already be sufficient for profiling by means of constraint-based peptide identification from databases (as done for LC-MS data) (Swaminathan et al. 2015 PLoS Comput Biol. 11:e1004080). Second, proteins are extremely heterogeneous in terms of physiochemical properties. This can be decreased to some extent by applying the bottom-up proteomics approach, i.e. the protease-mediated digestion of the proteome into peptides. The parallel sequencing of such a complex mixture of peptides, with a dynamic range of several orders of magnitude, will inevitably be facing huge technical hurdles. Complexity can be further decreased by purifying a subset of (proteotypic) peptides from the peptide pool. The sequencing of peptides through (solid-state) nanopores is currently the most popular platform under study. Extensive research is done on the engineering of nanopores that are able to translocate peptides and differentiate between amino acids or amino acid categories along the sequence (Kennedy et al. 2016 Nat Nanotechnol 11:968-976; Wilson et al. 2016 Adv Funct Mater 26:4830-4838). One other promising technology for the analysis of proteins in a sensitive and quantitative manner was developed by Mitra et al (WO 2010/065531). This technology, referred to as Digital Analysis of Proteins by End Sequencing or DAPES, features a method for single molecule protein analysis. To perform DAPES, a large number of proteins are denatured and cleaved into peptides. These peptides are immobilized on a nanogel surface applied to the surface of a microscope slide and their amino acid sequences are determined in parallel using a method related to Edman degradation. Phenyl isothiocyanate (PITC) is added to the slide and reacts with the N-terminal amino acid of each peptide to form a stable phenylthiourea derivative. Next, the identity of the N-terminal amino acid derivative is determined by performing, for example, 20 rounds of antibody binding with antibodies specific for each PITC-derivatized N-terminal amino acid, detection, and stripping. The N-terminal amino acid is removed by raising the temperature or lowering pH, and the cycle is repeated to sequence 12-20 amino acids from each peptide on the slide. The absolute concentration of every protein in the original sample can then be calculated based on the number of different peptide sequences observed. The PITC chemistry used in DAPES is the same used in Edman degradation and is efficient and robust (>99% efficiency). However, the cleavage of single amino acids requires strong anhydrous acid or alternatively, an aqueous buffer at elevated temperatures. Cycling between either of these harsh conditions is undesirable for multiple rounds of analysis on sensitive substrates used for single molecule protein detection (SMD).
An alternative peptide sequencing method uses N-terminal amino acid binding proteins (NAABs) instead of antibodies that bind PITC-derivatized N-terminal amino acids (WO20140273004). For every amino acid such a NAAB is developed which can be modified from an aminopeptidase or a tRNA synthetase. The NAABs are differently labelled and the N-terminal amino acid of a polypeptide is then identified by detecting the fluorescence label of a specific NAAB that is bound to the N-terminal amino acid upon incubation and washing of such NAABs. Moreover instead of a chemical/physical removal of the N-terminal amino acids, an enzyme called Edmanase (named after the Edman degradation) can be used. Although the Edmanase partially solves limitations from Mitra et al, this method relies on an arsenal of NAABs to derive amino acid identity information. NAABs for all different amino acids should be present together or added sequentially, adding complexity to this system. Moreover, the ability to develop NAABs with sufficient affinity to be used in single molecule sensing remains undemonstrated. Consequently, it would be advantageous to develop a more simple and elegant protein sequencing technology based on different physiochemical principles than mere binding affinity of reagents.

Means and methods for single molecule peptide sequencing


A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and a pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (nxe2x88x921)-th and (nxe2x88x922)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights have wavelengths corresponding to the channels than (nxe2x88x922)-th and (nxe2x88x923)-th channels may be multiplexed, thereby forming the pumping light source.

1. Field of the Invention
The present invention relates to a Raman amplifier capable of being used for amplification of optical signal in various optical communication systems, and optical repeater and Raman amplification method using such a Raman amplifier, and more particularly, it relates to Raman amplifier, optical repeater and Raman amplification method suitable for amplification of wavelength division multiplexing signals.
2. Related Background Art
Almost all of optical amplifiers used with present optical fiber communication systems are rare earth doped fiber amplifiers. Particularly, erbium doped optical fiber amplifier (referred to as xe2x80x9cEDFAxe2x80x9d hereinafter) using Er (erbium) doped fibers have been used frequently. However, a practical gain wavelength band of the EDFA has a range from about 1530 nm to 1610 nm (refer to xe2x80x9cElectron. Lett,xe2x80x9d vol.33, no.23, pp.1967-1968). Further, the EDFA includes gain having wavelength dependency, and, thus, when it is used with wavelength division multiplexing signals, difference in gain is generated in dependence upon a wavelength of optical signal. FIG. 23 shows an example of gain wavelength dependency of the EDFA. Particularly, in wavelength bands smaller than 1540 nm and greater than 1560 nm, change in gain regarding the wavelength is great. Accordingly, in order to obtain given gain (in almost cases, gain deviation is within 1 dB) in the entire band including such wavelength, a gain flattening filter is used.
The gain flattening filter is a filter designed so that loss is increased in a wavelength having great gain, and the loss profile has a shape substantially the same as that of the gain profile. However, As shown in FIG. 24, in the EDFA, when magnitude of average gain is changed, since the gain profile is also changed as show by curves a, b and c, in this case, the optimum loss profile of the gain flattening filter is also changed. Accordingly, when the flattening is realized by a gain flattening filter having fixed loss profile, if the gain of the EDFA is changed, the flatness will be worsened.
On the other hand, among optical amplifiers, there is an amplifier referred to as a Raman amplifier utilizing Raman scattering of an optical fiber (refer to xe2x80x9cNonlinear Fiber Optics, Academic Press). The Raman amplifier has peak gain in frequency smaller than frequency of pumping light by about 13 Thz. In the following description, it is assumed that pumping light having 1400 nm ban is used, and the frequency smaller by about 13 THz will be expressed as wavelength longer by about 100 nm. FIG. 25 shows wavelength dependency of gain when pumping light having central wavelength of 1450 nm is used. In this case, peak of gain is 1550 nm and a band width within gain deviation of 1 dB is about 20 nm. Since the Raman amplifier can amplify any wavelength so long as an pumping light source can be prepared, application of the Raman amplifier to a wavelength band which could not be amplified by the EDFA has mainly be investigated. On the other hand, the Raman amplifier has not been used in the gain band of the EDFA, since the Raman amplifier requires greater pump power in order to obtain the same gain as that of the EDFA. When the pumping light having great power is input to a fiber to increase the gain, stimulated Brillouin scattering may be generated. Increase amplification noise caused by the stimulated Brillouin scattering is one of the problems which makes it difficult to use the Raman amplifier. The Japanese Patent Laid-open No. 2-12986 (1990) discloses an example of a technique for suppressing the stimulated Brillouin scattering in the Raman amplifier.
Further, the Raman amplifier has polarization dependency of gain and amplifies only a component (among polarized wave components) coincided with the polarized wave of the pumping light. Accordingly, it is required for reducing unstability of gain due to polarization dependency, and, to this end, it is considered that polarization maintaining fiber is used as a fiber for amplifying or an pumping light source having random polarization condition.
Furthermore, enlargement of the gain band is required in the Raman amplifier. To this end, Japanese Patent Publication No. 7-99787 (1995) teaches in FIG. 4 that the pumping light is multiplexed with appropriate wavelength interval. However, this patent does not disclose concrete values of the wavelength interval. According to a document (K. Rottwitt, OFC98, PD-6), a Raman amplifier using a plurality of pumping lights having different wavelengths was reported; however, attempt in the viewpoint of the fact that the gain deviation is reduced below 1 dB was not considered.
On the other hand, there is an optical repeater for simultaneously compensating for transmission loss and chromatic dispersion in an optical fiber transmission line, which optical repeater is constituted by combination of an Er doped fiber amplifier (EDFA) and a dispersion compensating fiber (DCF). FIG. 46 shows a conventional example in which a dispersion compensating fiber A is located between two Er doped fiber amplifiers B and C. The first Er doped fiber amplifier B serves to amplify optical signal having low level to a relatively high level and has excellent noise property. The second Er doped fiber amplifier C serves to amplify the optical signal attenuated in the dispersion compensating fiber A to the high level again and has a high output level.
By the way, on designing the optical repeater, it is required that a repeater input level, a repeater output level and a dispersion compensating amount (loss in the dispersion compensating fiber A) be set properly, and, there is limitation that the input level of the dispersion compensating fiber A has an upper limit, because, when the input power to the dispersion compensating fiber A is increased, influence of non-linear effect in the dispersion compensating fiber A is also increased, thereby deteriorating the transmission wave form considerably. The upper limit value of the input power to the dispersion compensation fiber A is determined by self phase modulation (SPM) in one wave transmission and by cross phase modulation (XPM) in WDM transmission. Thus, regarding the optical repeater, an optical repeater having excellent gain flatness and noise property must be designed in consideration of the several variable factors.
FIG. 47 shows a signal level diagram in the repeater. Gain G1 [dB] of the first Er doped fiber amplifier B is set to a difference between an input level Pin [dB] of the repeater and an input upper limit value Pd [dB] to the dispersion compensating fiber A. Gain G2 [dB] of the second Er doped fiber amplifier C is set to (Gr+Ldxe2x88x92G1) [dB] from loss Ld [dB] in the dispersion compensating fiber A, gain Gr [dB] of the repeater and the gain G1 [dB] of the first Er doped fiber amplifier B. Since these design parameters are varied for each system, the values G1 [dB] and G2 [dB] are varied for each system, and, accordingly, the Er doped fiber amplifiers B, C must be re-designed for each system. The noise property in such a system is deeply associated with the loss Ld [dB] in the dispersion compensating fiber A, and it is known that the greater the loss the more the noise property is worsened. Further, at present, a yap from the designed value in loss in the transmission line and the loss in the dispersion compensating fiber A are offset by changing the gains of Er doped fiber amplifiers B, C. In this method, the gain of Er doped fiber amplifier B and C are off the designed value, thus the gain flatness is worsened. A variable attenuator may be used to offset the gap from the designed value of loss. In this method, although the gain flatness is not changed, an additional insertion loss worsens the noise property.
In the optical fiber communication system, although the Er doped optical fiber amplifiers have widely been used, the Er doped optical fiber amplifier also arises several problems. Further, the Raman amplifier also has problems that, since output of ordinary semiconductor laser is about 100 to 200 mW, gain obtained is relatively small, and that the gain is sensitive to change in power or wavelength of the pumping light. So that, when a semiconductor laser of Fabry-Perot type having relatively high output is used, noise due to gain fluctuation caused by its mode hopping becomes noticeable, and that, when the magnitude of the gain is adjusted, although drive current of the pumping laser must be changed, if the drive current is changed, since the fluctuation in the central wavelength is about 15 nm at the maximum, the wavelength dependency of gain will be greatly changed. Further, such shifting of the central wavelength is not preferable because such shifting causes change in joining loss of a WDM coupler for multiplexing the pumping light. In addition, the optical repeater also has a problem that the Er doped optical fiber amplifiers B, C must be re-designed for each system. Further, the deterioration of the noise property due to insertion of the dispersion compensating fiber is hard to be eliminated in the present systems.
In a Raman amplification method for amplifying optical signal by using a stimulated Raman scattering phenomenon, a communication optical fiber is used as an optical fiber acting as an amplifying medium, and, in a distributed amplifying system, a wavelength of pumping light and a wavelength of the optical signal are arranged in 1400nm-1600nm band having low loss and low wavelength dependency within a wide band of the communication optical fiber. In this case, regarding the loss of wavelength dependency of the optical fiber as the amplifying medium, a difference between maximum and minimum values is below about 0.2 dB/km in the above band, even in consideration of loss caused by hydroxylion (OH) having peak at 1380 nm. Further, even if each pumping powers in a multi-wavelength pumping system are not differentiated according to the wavelength dependence of the loss, the gain of the signals amplified by the pumping lights are substantially the same, there is no problem in practical use.
On the other hand, in a Raman amplifier operating as a discrete amplifier such as EDFA (rare earth doped fiber amplifier) it is necessary to pay attention to the package of the amplifier fiber, for a length of the fiber is about 10 km to about several ten of kilometers in order to obtain the required gain. Thus, it is convenient that the length of the fiber is minimized as less as possible. Although the length of the fiber can be shortened by using an optical fiber having great non-linearity, in the optical fiber having great non-linearity, it is difficult to reduce the transmission loss caused by (OH) generally having a band of 1380 nm, and Rayleigh scattering coefficient becomes great considerably in comparison with the communication fiber, with the result that the difference between the maximum and minimum values of fiber loss within the above-mentioned wavelength range becomes very great such as 1.5 to 10 dB/km. This means that, when the optical fiber having 1 length of 3 km is used, the loss difference due to the wavelength of the pumping light becomes 4.5 dB to 30 dB. Thus, the wavelength division multiplexing signals cannot be uniformly amplified by using the pumping lights having the same intensities.
As one of means for multiplexing the number of pumping lights, there is a wavelength combiner of Mach-Zehnder interferometer type. Since the Mach-Zehnder interferometer has periodical response property regarding frequency, the wavelength of the pumping light must be selected among wavelengths having equal intervals in frequency. Accordingly, the wavelength combiner of Mach-Zehnde interferometer type has limitation in degrees of freedom of wavelength setting, but has an advantage that, when a device of waveguide type or fiber fusion type, if the number of wavelength division multiplexing is increased, insertion loss is not changed substantially.
An object of the present invention is to provide a Raman amplification method capable of uniformly amplifying wavelength division multiplexing signals and suitable to be incorporated as a unit.
Another object of the present invention is to provide a Raman amplifier which can obtain required gain and can reduce wavelength dependency of gain to the extent that usage of a gain flattening filter is not required and which can be used in a band of EDFA.
A further object of the present invention is to apply the Raman amplifier to an optical repeater constituted by an Er doped fiber amplifier (EDFA) and a dispersion compensating fiber (DCF) thereby to provide an optical repeater in which the EDFA is not required to be re-designed for each system and which can compensate dispersion in transmission line loss and/or DCF loss without deteriorating property of the optical repeater.
Further, by Raman-amplifying the DCF, the deterioration of noise property due to insertion of the CF which could not avoided in the conventional techniques is reduced.
An example of a Raman amplifier according to the present invention is shown in FIGS. 1, 2 and 3. When a small-sized semiconductor laser 3 of Fabry-Perot type having relatively high output is used in a pumping means 1, relatively high gain can be obtained, and, since the semiconductor laser 3 of Fabry-Pero type has a wide line width of an oscillating wavelength, occurrence of stimulated Brillouin scattering due to the pumping light can be eliminated substantially. On the other hand, when a semiconductor laser of DFB type or DBR type, or a Mater Oscillator Power Amplifier (MOPA) is used in the pumping means 1, since a fluctuation range of the oscillating wavelength is relatively small, a gain configuration is not changed by a driving condition. Further, occurrence of stimulated Brillouin scattering can be suppressed by effecting modulation.
Further, by selecting the interval between the central wavelengths of the pumping light to a value greater than 6 nm and smaller than 35 nm, the wavelength dependency of gain can be reduced to the extent that the gain flattening filter is not required. The central wavelength xcexc in this case is a value defined regarding the single pumping light and is represented by the following equation when it is assumed that a wavelength of an i-th longitudinal mode of laser oscillating is xcexi and light power included in that mode is Pi:       λ              xe2x80x83            c    =                    ∑                              xe2x80x83                              i                                  xe2x80x83                          Pi                          xe2x80x83                        λ                          xe2x80x83                        i                            ∑                              xe2x80x83                              i                                  xe2x80x83                  Pi
The reasons why the interval between the central wavelengths of the pumping light is selected to value greater than 6 nm is that the oscillating band width of the semiconductor laser 3 of Fabry-Perot type connected to an external resonator having narrow reflection band width is about 3 nm as shown in FIG. 12, and that a WDM coupler 11 (FIGS. 1, 2 and 3) for combining the pumping lights is permitted to have certain play or margin in wavelength interval between the pumping lights in order to improve wave II combining efficiency. The WDM coupler 11 is designed so that lights having different wavelengths are received by different ports and the incident lights are joined at a single output port substantially without occurring of loss of lights. However, regarding light having intermediate wavelength between the designed wavelengths, the loss is increased even whichever port is used. For example, in a certain WDM coupler 11, a width of a wavelength band which increases the loss is 3 nm. Accordingly, in order that the band of the semiconductor laser 3 is not included within said band, as shown in FIG. 12, a value 6 nm obtained by adding 3 nm to the band width of the semiconductor laser 3 is proper for low limit of the interval between the central wavelengths of the pumping light. On the other hand, as shown in FIG. 13A, if the interval between the central wavelengths of the semiconductor laser 3 is greater than 35 nm, as shown in FIG. 13B, a gain valley is created at an intermediate portion of the Raman gain band obtained by the pumping lights having adjacent wavelengths, thereby worsening the gain flatness. The reason is that, regarding the Raman gain obtained by the single pumping light, at a position spaced apart from the gain peak wavelength by 15 nm to 20 nm, the gain is reduced to half. Accordingly, by selecting the interval of the central wavelengths of the pumping light to the value greater than 6 nm and smaller than 35 nm, the wavelength dependency of gain can be reduced to the extent that the gain flattening filter is not required.
According to a second aspect of the present invention, since a Raman amplifier has a control means 4 for monitoring input light or output light with respect to the Raman amplifier and for controlling pump powers of the pumping means 1 on the basis of a monitored result to maintain output light power of the Raman amplifier to a predetermined value, given output can be obtained regardless of fluctuation of input signal power to the Raman amplifier and/or dispersion in loss of a Raman amplifier fiber.
According to a third aspect of the present invention, since a Raman amplifier has a controlling means 4 flattening Raman gain, the gain can be flattened. Particularly, as shown in FIG. 16, by monitoring lights having wavelengths obtained by adding about 100 nm to the wavelengths of the pumping lights, respectively, and by controlling the powers of the pumping lights to order or align the monitored light powers, the gain can be flattened: Further, since a wavelength stabilizing fiber grating (external resonator 5) which will be described later can suppress the shift in the central wavelength due to change in drive current of a Fabry-Perot type semiconductor laser, it can also be used as a means for permitting control of the gain.
According to a fourth aspect of the present invention, since a Raman amplifier has a control means 4 for monitoring input signal power and output signal power and for controlling pumping light power to make a ratio between the input signal power and the output signal power constant thereby to maintain gain of the Raman amplifier to a predetermined value, given output can be obtained regardless of fluctuation of the input signal power to the Raman amplifier and/or dispersion in loss of a Raman amplifier fiber.
According to a fifth aspect of the present invention, in a Raman amplifier, since an optical fiber having non-linear index n2 of refraction of 3.5Exe2x88x9220 (m2/W) or more is used as an optical fiber 2, adequate amplifying effect can be obtained, from the result of investigation.
According to a sixth aspect of the present invention, in a Raman amplifier, since the optical fiber 2 exists as a part of a transmission fiber for propagating the optical signal, the amplifier can be incorporated into the transmission optical fiber as it is.
According to a seventh aspect of the present invention, a Raman amplifier utilizes a part of a dispersion managed transmission line and can constitute an amplifier as it is as amplifying medium.
According to an eighth aspect of the present invention, in a Kaman amplifier, since the optical fiber 2 exists as an amplifier fiber provided independently from a transmission fiber for propagating the optical signal and inserted into the transmission fiber, an optical fiber suitable for Raman amplification can easily be used for the optical fiber 2 and the chromatic dispersion compensating fiber can easily be utilized, and a discrete amplifier can be constituted.
In an optical repeater according to the present invention, since loss of an optical fiber transmission line 8 is compensated by using the Raman amplifier, an optical repeater having the function of the Raman amplifier can be provided.
Among optical repeaters of the present invention, in a repeater in which rare earth doped fiber amplifier(s) 10 is (are) provided at preceding or following stage or at both stages of the Raman amplifier, since the loss of the optical fiber transmission line 8 is compensated by the Raman amplifier 9 and the rare earth doped fiber amplifier(s) 10, desired amplifying property suitable for various transmission systems can be obtained.
Among optical repeaters of the present invention, in accordance with an arrangement in which the Raman amplifier 9 and the rare earth doped fiber amplifier 10 are combined, a repeater adapted to various systems can be obtained. This fact will be explained hereinbelow as an example that DCF is used as the amplifier fiber of the Raman amplifier 9. FIG. 17 shows design parameters of a convention 1 optical repeater, and the gains G1, G2 are varied for each system. Further, it is not inevitable that input of the repeater and loss of the DCF are fluctuated by scattering in repeater spacing and scattering in the DCF. Such fluctuation is directly associated with the fluctuation of the gain of the ED , which fluctuation of the gain leads to deterioration of flatness. FIG. 18 schematically shows a relationship between the flatness and the gain of the EDFA. Since the flatness is optimized by limiting the used band an the average gain, if the average gain is deviated from the optimum point, the wavelength dependency of gain is changed to worsen the flatness. In order to avoid the deterioration of the flatness, the gain of the EDFA must be kept constant. Conventionally, a variable attenuator has been used as a means for compensating the fluctuation in input level and loss of the DCF. FIG. 19A shows an example that an attenuating amount of the variable attenuator is adjusted in accordance with the fluctuation of the input level to control the input level to the DCF to be kept constant and FIG. 19B shows an example that an attenuating amount is adjusted in accordance with the fluctuation in loss of the DCF to control intermediate loss to be kept constant. In both examples; the gains of two amplifiers are constant. However, in these methods, since useless loss is added by the variable attenuator, there is an disadvantage in the viewpoint of noise property. In the present invention, by compensating the change in design parameters of the repeater by the Raman amplification of the DCF, the gain of the EDFA is kept constant, requirement that the EDFA be re-designed for each system is eliminated, and the scattering in repeater spacing and scattering in the DCF can be compensated without sacrificing the flatness and the noise property. FIG. 20 shows design values of the EDFA when the Raman amplification of the DCF is applied to the specification of the repeater of FIG. 17. By selecting the Raman gain of the DCF appropriately, the properties of the EDFA required for three specifications can be made common. Further, as shown in FIGS. 21A and 21B, the fluctuation in input level and in loss of the DCF can be compensated by changing the Raman gain without changing the gain of the EDFA. In any cases, the Raman gain is adjusted so that the output level of the DCF becomes constant, while keeping the gain of the EDFA constant. Further, by compensating the loss of the DCF itself by the Raman amplification, the deterioration of the noise property due to insertion of the DCF which could not avoided in the conventional techniques can be reduced. FIG. 37 shows measured values of a deteriorating amount of the noise figure when the DCF is inserted and of a deteriorating amount of the noise figure when the Raman amplifier using the same DCF is inserted.
In the optical repeater according to the present invention, when a Raman amplifier using an pumping light source in which wavelengths are not combined is provided, although an operating wavelength range is narrower, a construction can be simplified and the same property as the aforementioned optical repeaters can be obtained, except for the band width, in comparison with an optical repeater having a Raman amplifier pumped by a plurality of wavelengths. FIGS. 38 and 39 show measured examples of the optical repeater using the Raman amplifier pumped by the pumping light source in which wavelengths are not combined and of the optical repeater using the Raman amplifier pumped by the plurality of wavelengths.
In the Raman amplifier according to the present invention; when a difference between maximum and minimum values of the central wavelength of the pumping light is within 100 nm, overlapping between the pumping light and the optical signal can be prevented to prevent wave form distortion of the optical signal. If the wavelength of the pumping light is similar to the wavelength of the optical sign 1, since the wave form of the optical signal may be deteriorated, the wavelength of the pumping light and the wavelength of the optical signal must be selected so that they are not overlapped. However, in a case where the pumping light has band of 1.4 xcexcm, when the difference between the maximum and minimum values of the central wavelength of the pumping light is smaller than 100 nm, as shown in FIG. 14, since the difference between the central wavelength of the gain caused by one pumping light and the wavelength of such pumping light is about 100 nm, the overlapping between the wavelength of the pumping light and the wavelength of the optical signal can be prevented.
In the Raman amplifier according to the present invention, when the pumping lights having adjacent wavelengths are propagated through the optical fiber 2 toward two different directions so that the optical signal pumped bi-directionally, the wavelength property required in the WDM coupler 11 shown in FIG. 1 and FIGS. 2 and 3 can be softened. The reason is that, as shown in FIG. 15, in all of pumping lights from both directions, although the central wavelengths become xcex1, xcex2, xcex3, xcex4 and the interval is greater than 6 nm and smaller than 5 nm, when considering the pumping lights from only one direction, the central wavelengths become 80 1 and xcex3 or xcex2 and xcex4 and the wavelength interval increased to twice, with the result that the property required in the WDM coupler 11 can have margin or play.
In the Raman amplifier according to the present invention, when the wavelength stabilizing external resonator 5 such as fiber grating is provided at the output side of the semiconductor laser 3 of Fabry-Perot type, noise due to fluctuation of caused by mode hopping of the semiconductor laser 3 of Fabry-Perot type can be suppressed. In consideration of one pumping light source, it makes the bandwidth narrower to connect the wavelength stabilizing external resonator 5 to the semiconductor laser 3. Since it also results the smaller wavelength interval in case of combining pumping light sources by the WDM coupler 11 (FIGS. 1, 2 and 3), pumping light having higher output and wider band can be generated.
In the Raman amplifier according to the present invention, when the pumping light of the semiconductor laser 3 is used to be polarization-combined for each wavelength, not only polarization dependency of gain can be eliminated but also the pump power launched into the optical fiber 2 can be increased. In the Raman amplification, only the components matched with the polarized of the pumping light can be given the gain. When the pumping light is linear-polarized and the amplifier fiber is not a polarization maintaining fiber, the gain is changed due to fluctuation of relative state of polarization of the signal and the pumping light. Therefore, the polarization dependence of gain can be eliminated by combining two linear-polarized pumping lights so that the polarization planes are perpendicular to each other. Further, it increases the pumping light power launched into the fiber.
In the Raman amplifier according to the present invention, in the case where a wavelength combiner of planar lightwave circuit based on a Mach-Zehnder interferometer is used as a means for wave-combining MOPA or a semiconductor laser of Fabry-Perot type, DFB type or DBR type having a plurality of wavelengths, even when the number of the wavelengths to be combined is large, the wave-combination can be achieved with very low loss, and pumping light having high output can be obtained.
In the Raman amplifier according to the present invention, as shown in FIG. 6, as, when a polarization plane rotating means 7 for rotating the polarization plane by 90 degrees is provided so that the optical fiber 2 simultaneously includes the plurality of pumping lights generated by the pumping means I and the pumping lights having a orthogonal state of polarization to the pumping lights generated by the pumping means 1, in principle, given gain can always be obtained regardless of the state of polarization of the optical signal, with the result that the band of the Raman gain can be widened.
In the optical repeater according to the present invention, when the Raman amplification is utilized by coupling residual pumping light of the Raman amplifier to the optical fiber transmission line 8, a part of loss of the optical fiber transmission line 8 can be compensated.
In the optical repeater according to the present invention, when the residual pumping light of the Raman amplifier is utilized as pumping light for the rare earth doped fiber amplifier 10, the number of the semiconductor lasers to be used can be reduced.
In the optical repeater according to the present invention, when a dispersion compensating fiber is used as the optical fiber 2 of the Raman amplifier 9, the chromatic dispersion of the optical fiber transmission line 8 can be compensated by the Raman amplifier 9, and a part or all of the losses in the optical fiber transmission line 8 and the amplifier fiber 2 can be compensated.
According to a twenty-ninth aspect of the present invention, in a Raman amplification method by stimulated Raman scattering in an optical fiber through which two or more pumping lights having different central wavelengths and said optical signals are propagated, the pumping power launched into said optical fiber increases as the central wavelengths of said pumping lights is shorter.
According to a thirtieth aspect of the present invention, in a Raman amplification method by stimulated Raman scattering in an optical fiber through which two or more pumping lights having different central wavelengths and said optical signals are propagated, total pumping power on the shorter wavelength side with respect to the center between the shortest and longest central wavelengths among said two or more pumping lights is greater than on the longer side.
According to a thirty-first aspect of the present invention, in a Raman amplification method by stimulated Raman scattering in an optical fiber through which three or more pumping lights having different central wavelengths and said optical signals are propagated, the number of the pumping light sources on the shorter wavelength side with respect to the center between the shortest and longest central wavelengths among said three or more pumping lights is greater than on the longer side, and the total pumping power on the shorter wavelength side is greater than on the longer side.
To achieve the above object, according to thirty-second to thirty-fourth aspects of the present invention, when the shortest pumping wavelength is defined as a first channel and, from the first channel, at respective intervals of about 1 THz toward the longer wavelength, second to n-th channels are defined, pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed and pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength is combined with the multiplexed light, and light obtained in this way is used as the pumping light of the Raman amplifier. When the shortest pumping wavelength is defined as the first channel and, from the first channel, at respective interval of about 1 THz toward the longer wavelength, the second to n-th channels are defined, light obtained by combining all of the wavelengths corresponding to the channels other than (nxe2x88x921)-th and (nxe2x88x922)-th channels is used as the pumping light of the Raman amplifier. Alternatively, light obtained by combining all of the wavelengths corresponding to the channels other than (nxe2x88x922)-th and (nxe2x88x923)-th channels is used as the pumping light of the Raman amplifier.

Raman amplifier, optical repeater, and raman amplification method


A device for imparting rotational movement to a satellite during discharge from an adapter of a launcher. The satellite includes a first axis, a second axis, and a third axis passing through a center of gravity. The first axis, the second axis, and the third axis are mutually perpendicular. The device includes at least one line dismountably attached to a first point on the satellite and a first point on the adapter. The at least one line is attached to the satellite and the adapter such that the at least one line imparts a rotational movement to the satellite as the satellite is discharged and separates from the adapter with a discharge velocity in a direction along the first axis. A lock dismountably attaches the at least one line to the satellite.

When launching satellites with a launcher, which is provided at its top with an adapter. The adapter is arranged to dismountably hold the satellite until the moment. When the satellite is separated, it is usual to give the satellite a rotational movement around a velocity vector. That is to say, the satellite is caused rotate around a first axis, the spinning axis. In certain cases it is desired to give the satellite a rotational movement around a second axis, that forms an angle, especially a right angle, to the spinning axis. This can be achieved by providing the adapter with separation springs, directed in corresponding ways, or by designing the separation springs accordingly differently. As need for rotational velocity around the second axis increases larger and, thus, heavier separation springs are required. There is thus a demand for a simple and safe device to impart movements to satellites as described above. The object of the present invention is to create such a device.

Device at the adapter of a launcher and a satellite carried by the adapter