A machine for the harvest of stalk-like plants is provided. The machine has a frame, two conveying elements supported on the frame and arranged one above the other with recesses distributed around their circumference for taking up and conveying a flow of crop that includes plant stalks. A stripper extends into the intervening space between the conveying elements in order to move the plant stalks out of the recesses. The stripper is connected to the frame by a free-standing post that extends vertically and is arranged outside the flow of the crop conveyed by the conveying elements. A point of the stripper interacts with the conveying elements located to the rear of the axis of rotation of the conveying elements relative to the forward operating direction of the machine.

Machines appropriate for the harvesting of stalk-like plants, such as corn, and for attachment to a forage harvester are described in publications DE 195 31 918 A and DE 102 58 013 A, such machines are provided with several mowing and intake arrangements arranged transverse to the forward operating direction in which the machine is moved over a field during the harvesting operation. The mowing and intake arrangements include a lower cutter disk in the form of a circular saw blade and conveying disks arranged above these that are provided with recesses which accept plants. The cutting disks are brought into rotation at higher speeds than the conveying disks. Once they have been separated from the stubble remaining in the ground by means of the cutting disks, the plants are accepted by the conveying disks and transported to the center of the machine by the conveying disks into the transverse conveying disks arranged in the gore regions between the conveying disks on the rear sides of the mowing and intake arrangements and delivered to an intake channel of a forage harvester by slope conveyor drums.
In order to lift the plants out of the conveying disks for further delivery to the following transverse conveying drums or conveying disks, so-called strippers are provided, whose points extend into the intervening space between two conveying disks arranged one above the other. The strippers are connected to the bottom of the machine by vertical posts at a short distance downstream of the point. Such strippers are also called cleaning devices or take-out devices. Further strippers are also associated with the transverse conveying drums and the slope conveying drums. They are connected to the bottom of the machine by posts at the output ends of the transverse conveying drums and the slope conveying drums.
EP 0 069 898 A describes a machine of the type cited initially that includes two mowing and intake arrangements with lower cutting disks and conveying disks arranged above these that contain recesses distributed around their circumferences that accept plants. S-shaped strippers are arranged to the rear of the mowing and intake arrangements, the points of the strippers located upstream extend into the intervening vertical space between two conveying disks. The harvested crop is conveyed along the rear sides of the strippers. Posts extending vertically downward are fastened to the rear sides of the mowing and intake arrangements, the posts, in turn, are fastened with their lower ends to gearbox housings of the mowing and intake arrangements. Here the post is separated from the flow of the crop only by the strippers, so that, here too, plants can be wrapped around the posts.
DE 199 52 566 C describes another machine for the harvesting of stalk-like plants with chains arranged one above the other to which drivers are attached that project outward for the conveying of plants. The chains circulate about deflecting sprockets that rotate about vertical axes. Cutting elements are attached below the chains to cut the plants from the stubble remaining in the ground. Sheet metal components used as strippers are arranged at the outlet end between chains following each other, one above the other, which are connected to the bottom of the machine by posts arranged to the rear of the deflecting sprockets. Here the posts are also located in the flow of the crop, so that plants may become entangled with them.
EP 0 508 189 A proposes another machine for the harvest of stalk-like plants that also includes rotating mowing and intake arrangements with lower cutting disks and upper conveying disks. Each of the mowing and intake arrangements adjoining the longitudinal center plane of the machine is associated with a single stripper that is attached to an upper horizontal cover that is stationary and is fastened to the center of the machine. A stationary cover is required for the attachment of the stripper that can be arranged in the center of the machine only if the outer mowing and intake arrangements are also to convey the harvested crop to the rear of the machine.
Finally, GB 20 12 154 A describes a machine for the harvest of stalk-like plants that also includes rotating mowing and intake arrangements with lower cutting disks and upper conveying disks. Strippers are connected with the bottom of the machine ahead of the axis of rotation of the mowing and intake arrangements and to the side walls of a stalk divider and at the outlet end to the rear side of the mowing and intake arrangements.

Machine for harvesting stalk-like plants with a stripper


A patient interface device includes a support structure, a pivot arm pivotably coupled to the support structure and structured to pivot about an axis, a patient coupling member, such as a mask or a forehead support, coupled to the pivot arm, and a cam wheel rotateably coupled to the support structure and engaging the pivot arm, wherein rotation of the cam wheel relative to the support structure and the pivot arm causes the pivot arm to pivot about the axis and the patient coupling member to move either forward or backward along a path of movement. Also, an alternative patient interface device includes a cam wheel rotatable about a cushion member that changes a position of a main body portion of the cushion member relative to a headgear frame member of the patient interface device.

1. Field of the Invention
The present invention relates to patient interface devices for transporting a gas to and/or from an airway of a user, and, in particular, to a patient interface device including a cam wheel adjustment mechanism for dynamically adjusting a component of the patient interface device, such as a mask, cushion, or forehead support.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), or congestive heart failure.
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device including a mask component on the face of a patient. The mask component may be, without limitation, a nasal mask that covers the patient's nose, a nasal cushion having nasal prongs that are received within the patient's nares, a nasal/oral mask that covers the nose and mouth, or a full face mask that covers the patient's face. The patient interface device interfaces the ventilator or pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient. It is known to maintain such devices on the face of a wearer by a headgear having one or more straps adapted to fit over/around the patient's head.
Because such patient interface devices are typically worn for an extended period of time, it is important for the headgear to maintain the mask component of the device in a tight enough seal against the patient's face without discomfort. A number of different adjustment mechanisms for adjusting a component, such as a mask, of a patient interface device are known, including adjustment mechanisms that are based on sliding members, screw mechanisms, and pivoting arms, among others. However, all of these known mechanisms are based on a linear adjustment theory, and thus have a range of motion that goes either inward or outward with respect to the patient's face. There is thus room for improvement in the area of patient interface device adjustment mechanisms.

Patient interface device having cam wheel adjustment mechanism


A stroller 10 includes a body structure 10a and a child car set 40 capable of detachably mounted on the body structure 10a. The body structure 10a has a handle 15 having a pair of straight parts 15a and a shape resembling the inverted letter U. Armrest bars 16 have base parts respectively connected to the straight parts 15a of the handle 15. Connecting members 17 are attached respectively to front end parts of the armrest bars 16. A support frame 28 for supporting the child car set 40 is extended between the connecting members 17. End caps 29 are detachably put on opposite end parts of the support frame 28, respectively. Brackets 32 for supporting front side parts 40a of the child car set 40 thereon are provided to the straight parts 15a of the handle 15. Each of the brackets 32 has at least two steps 32a and 32a formed respectively at different levels.

Generally, a child car set attached to the seat of a passenger car is used for carrying a baby of, for example, an age below one year in the passenger car. A stroller proposed in Patent document 1 can carry a child car set. A child car set attached to the seat of a passenger car holds a baby seated thereon until the passenger car arrives at a destination. Then, the child car set holding the baby is removed from the seat of the passenger car and is used as a seat for the stroller proposed in Patent document 1 to facilitate carrying around the baby at the destination.
Patent document 1: JP 2002-205586 A
Incidentally, such a stroller capable of being detachably provided with a child car set is provided with a child car set support frame extended between right and left armrests included in a body structure of the stroller. The child car set is fixedly mounted on the stroller with the child car set support frame engaged in a groove formed in the bottom surface of a rear part of the child car set.
Different child car sets manufactured by different manufacturers have different dimensions, respectively. Therefore, child car sets having dimensions not conforming to the size of the body structure of the stroller cannot be fixedly mounted on the stroller. The child car set support frame needs to be replaced with another one or needs to be turned for the adjustment of dimensions and angular position thereof or the stroller is able to support only limited types of child car sets.


Devices convert non-uniform rotational motion into uniform rotational motion and vice versa. A motion conversion mechanism includes a housing, a common shaft, a symmetrical differential reduction gear, rings for differential power flows, cams having an inner working surface, cams having an outer working surface, and sliders with fingers. The inner working surface cam profile is described by the polar radius as a function of the polar angle and is an equidistant curve distanced outwardly from a first-order derivative of a basic closed curve by the size of the finger's radius. The outer working surface cam profile is described by the polar radius as a function of the polar angle and is an equidistant curve distanced outwardly from a second-order derivative of a basic closed curve by the size of the finger's radius. In a single revolution of the shaft, each ring performs two half revolutions back and forth.

Prior art includes the mechanism for transformation movement, RU 2374526, F16H 25/04 (2006.01), wherein rhomb-shaped pivoted four-bar motion with pins interacting with cams and slide-rails has been disclosed.
There is known rotary-vane engine with Kauertz connection mechanism containing mechanism of vanes connection made as a main revolving mechanism connected with rotary axis of rotors by gear (U.S. Pat. No. 3,144,007, Aug. 11, 1964).
Common deficiencies of such mechanism include significant loads on construction components due to conversion of movement through the single-loop power flows, impossibility to secure full blocking of one of power flows during calculated part of period upon simultaneous pure conversion of second power flow and relatively small efficiency of such mechanism caused thereby, in conjunction with availability of parasite load from one of the power flows, opposed to useful load taken off the second power flow.
There is also a mechanism for movement conversion which is the closest to the subject technical solution and which is used in rotary vane internal combustion engine, RU 2225513, F01C 1/077 (2000.01), wherein doubled maltese mechanism is used, and wherein one cross is rotated relatively to another to a half of angle of maltese cross, and differential converts rotary-intermittent movement of working shafts into rotation of engine outcome shaft with constant angle velocity.
This mechanism allows to provide full alternate blocking of one of power flows upon simultaneous pure conversion of second power flow.
Deficiency of this device is the lack of smoothness of movement conversion and bigger impact loads in the moment of stopping maltese cross mechanism.


A ballast circuit for a discharge tube such as a fluorescent tube, mercury vapor, sodium vapor or metal halide lamp is disclosed. D.C. power is provided alternately between two output driver stages and an a.c. neutral return line. In output transformerless (OTL) embodiments of the invention, a series connection of a reactance circuit and the tube is connected between the push pull point and the a.c. neutral return line. In transformer embodiments of the invention, a primary winding of a transformer is connected in series with the reactance circuit. The tube or load is connected across an output winding of the transformer with the electrical effect that the load is in series with the reactance circuit. Alternative arrangements of transformer input windings are provided. The first includes two input primary windings wound in opposite directions with the circuit arranged such that current flows in one or the other of the input transformer windings on alternating half cycles of the control signal. The second includes a single input primary winding, but current flows through it in opposite directions on alternating half cycles. The d.c. current is provided by first and second rectifiers which provide positive and negative voltage levels with respect to an a.c. neutral line. RFI reduction circuitry is provided with the ballast circuit.

1. Field of the Invention
This invention relates in general to a ballast circuit for a discharge tube and in particular to a high frequency electronic power supply and ballast circuit for a fluorescent tube.
2. Description of the Prior Art
High speed switching solid-state electronic power supplies and ballasts can be designed to be smaller, lighter and more efficient than conventional core and coil transformers and ballasts designed for the same end use. They work by converting a.c. to d.c., then switching the d.c. at speeds much higher than the original a.c.. These highers speeds, between 30 and 30,000 times the incoming frequency, permit a drastic reduction in the size and weight of the magnetic components such as inductors and transformers.
There are numerous examples of prior art electronic ballast circuits for discharge tubes. For example, U.S. Pat. No. 4,370,600 issued Jan. 25, 1987, to Zansky concerns a two-wire electronic dimming ballast for fluorescent lamps. Filaments of the lamps are supplied by auxiliary coils of an inductor connected in series with a capacitor in a series resonant bridge inverter. The power to the lamps is supplied via such capacitor.
U.S. Pat. No. 4,392,087 issued July 5, 1983 to Zansky concerns a two-wire electronic dimming ballast circuit for gaseous discharge lamps which illustrates at FIG. 6 a positive feedback self-oscillating circuit for switching rectified d.c. voltage to the primary of a transformer. A tuning capacitor is connected across the main secondary winding. The system provides a sine wave input at the natural oscillating frequency of a half-bridge inverter circuit as determined by the leakage inductance of the main secondary winding and the tuning capacitor. FIGS. 7 and 8 of the '087 illustrate alternative embodiments of the circuit of FIG. 6.
U.S. Pat. No. 4,045,711 issued Aug. 30, 1977 to Pitel illustrates another tuned oscillator ballast circuit, but a series inductive winding and capacitor are provided in the input of a transformer which are series resonant at the oscillating frequency.
While the electronic ballast circuits described above as well as others have certain advantages, their effectiveness in striking and thereafter regulating the current applied to a discharge tube such as a fluorescent bulb has been less than ideal. For example, such circuits have not been ideally effective in reducing RFI/EMI generated by the HID or fluorescent bulb.


A flexible circuit board connecting device comprises a flat connector (10) to be connected to a predetermined circuit member, a flexible circuit board (1) to be connected to the circuit member via the connector (10). The connector (10) comprises a flat housing having a plurality of holding holes (12), a plurality of terminals (14) held in the holding holes (12). Each terminal (14) has a connection section (14A) to be connected to the circuit board and a contact section (14D) to be connected to the flexible circuit board. The contact points between the flexible circuit board and the terminals are made movable along the flexible circuit board from the zero insertion position to the contact position under spring forces.

1. Field of the Invention
The present invention relates to a technology of an electrical connector, particularly, to a mechanism to connect a flexible circuit board to a connector.
2. Description of the Related Art
A flexible circuit board is comprised of a flexible board, wirings provided on the flexible board and connection pads to be conductive through wirings, which are provided on the edge of the flexible board. When the flexible circuit board is used, it is placed onto a flat type connector, and then pressed and held, so that the connection pads contact with corresponding terminals of the connector. Such connection structure is known, for example, by disclosures in Japanese Unexamined Patent Publications Nos. 8-255961, 8-227745 and 3-182075.
In this type of connectors, the flexible circuit board or the connector has a flat connecting section (e.g. connection pad), and the other, the one between the flexible board and the connector which does not have the flat connect section, has a protruding elastic contact section. By putting in place and then pressing the flexible circuit board and the connector, such that the protruding elastic contact section is pressed to/into the flat contact section, the connection between the flexible circuit board and the connector is achieved and maintained. Therefore, the connection is achieved without an inserting force for engagement, such as the one required for the connection of terminals of normal connector. Also, since the terminals are arranged in columns and rows in those methods, the contact points to prevent the inserting force from becoming too large.
In such publicly known devices, a pressuring member is used to press the flexible circuit board towards the connector. According to the mechanism of the pressuring member, it is difficult to press the whole area of the connecting section of the flexible circuit board by the pressuring member to connect with the connector. Therefore, the pressuring member merely presses locally, for example, on both edges.
Since the flexible circuit board is flexible itself, it causes a distortion, such as deflection or torsion, if it is locally pressed. In other words, the connecting pressure is not uniformly applied to an area of the connecting section, which causes poor connection or the like, so that its electrical properties become unstable. Those problems are more conspicuously observed for flexible circuit boards having a large number of connection pads (contact points).
Accordingly, it is an object of the present invention to provide a structure for the connection of the flexible circuit board, which enables uniform and stable connection without such problems even when the flexible circuit board has a large number of contact points.
According to the present invention there is provided the flexible circuit board connecting device comprises a flat-type connector to connect with a specified circuit member and a flexible circuit board to connect with the circuit member via the connector.
In the flexible circuit board connecting device according to the present invention, the connector holds a plurality of terminals in holding holes of a housing, and each terminal has a connecting section on one side of the housing to connect with a circuit board and a contact section on the other side to contact with the flexible circuit board. The contact section between flexible circuit and the terminal can move opposing each other in a direction parallel to the surface of the flexible circuit board from specified zero inserting force position, where the flexible circuit board and the connector are contacted over the surface by zero inserting force, to a contact position, where the flexible circuit board and the connector are contacted under elastic pressure.
According to the present invention, the flexible circuit board is brought to a position, where its contact portion is close to the contact position of the corresponding terminal, by zero inserting force, and then moved in a direction of the surface, so that the contact portion comes to contact with the contact section under an elastic pressure. Each contact portion and its corresponding contact section simultaneously contact under the same condition, so that all the contact portions and their corresponding sections can evenly be contacted without uneven contact due to the flexibility of the flexible circuit board.
In an embodiment of the present invention, the device is made as follows. The contact section of the connector is formed on an elastic arm, which protrudes from the other side of the housing and extends along the surface. A window is provided to the housing for receiving the elastic arm at the zero inserting force position, and a connection pad is provided near the window. The contact portion is contacted with the connection pad under an elastic pressure at the time of relative movement towards the contact position.
In this case, the terminal of the connector is made to have another arm to tightly press the flexible circuit board by moving in concert with the elastic arm. By doing this, the contact between the flexible circuit board and the connector is further ensured. In this embodiment, the connecting pad and the window of the flexible circuit board and their corresponding terminals are arranged in columns and rows so that the number of the contact points can be increased.
In another embodiment of the present invention, the flexible circuit board is made as follows. The flexible circuit board has a contact pin to connect with the terminal of the connector, which is provided so as to protrude from the surface of the flexible circuit board towards the connector. The contact pin is put into the holding hole of the connector at the zero inserting force position, and contacts with the contact section of the terminal under an elastic pressure through the movement of the flexible circuit board towards the contact position.
In this case, the terminal of the connector is made such that the contact section tightly presses the contact pin so that the contact can be further ensured. Even in this embodiment, each contact pin of the flexible circuit board and its corresponding terminal of the connector are arranged in columns and in rows, so that the number of the contact points can be increased. The embodiments of the present invention are described below, particularly referring to the accompanying figures, FIGS. 1 through 4.

Flexible circuit board connecting device


Diffraction-based imaging systems are described. Aspects of the technology relate to imaging systems having one or more sensors inclined at angles with respect to a sample plane. In some cases, multiple sensors may be used that are, or are not, inclined at angles. The imaging systems may have no optical lenses and are capable of reconstructing microscopic images of large sample areas from diffraction patterns recorded by the one or more sensors. Some embodiments may reduce mechanical complexity of a diffraction-based imaging system. A diffractive imaging system comprises a light source, a sample support configured to hold a sample along a first plane, and a first sensor comprising a plurality of pixels disposed in a second plane that is tilted at an inclined angle relative to the first plane. The first sensor is arranged to record diffraction images of the light source from the sample.

Cancer is one of the leading causes of death in the United States. Each year over 1.5 million people are newly diagnosed with cancer in the United States alone. Over 500,000 Americans die from cancer annually and many more suffer from it. The burden of the disease is not limited to cancer patients but extends to their families and social circles. The loss of a loved one can be devastating, and even when the cancer patient survives, the uncertainty is emotionally trying. Cancer exacts an economic toll as well: the estimated direct medical costs for cancer treatment in the United States in 2014 were $87.8 billion, and some sources project that this number could exceed $200 billion in the near future. In addition to cancer, other burdensome diseases, such as Alzheimer's disease, Parkinson's disease, diabetes, cystic fibrosis, sickle cell anemia, and autoimmune diseases, continue to affect the lives of millions of people, either directly or indirectly, every year.
While significant resources have been dedicated to treating such diseases, in almost all cases, early and accurate detection is crucial to successful outcomes. Furthermore, because many treatments are painful and carry their own set of patient risks, accurate diagnoses are essential before beginning treatment. It is for that reason that preliminary screens such as mammograms, prostate exams, and pap tests are followed up with tissue biopsies when abnormalities are found.

Imaging systems with angled sensors and related methods


A readout board for use in a micropattern gas detector comprises a plurality of detector pads arranged into a plurality of consecutive layers that are separated by dielectric spacer material. An electron cloud hitting the front side of the readout board will induce a charge on one of the detector pads of the uppermost layer. By capacitive coupling, the signal will propagate downwards through the consecutive layers until it reaches the bottom layer, from which the charges are read out and analyzed. The position of the impact can be determined by comparing the charges that have spread to neighboring readout pads. Since only the bottommost layer of the readout pads needs to be connected to readout electronics, incident particles can be localized at high precision despite the relatively large size of the readout pads in the bottom layer. The invention is effective both in a gas electron multiplier (GEM) and in a MicroMegas detector.

Particle detectors are devices to detect, track, and/or identify radiation or particles and find wide applications throughout particle physics, biology as well as medical technology.
Particle detectors exploiting the process of ionization and charge multiplication in gases have been in use with continued improvements ever since Rutherford first employed a gas-filled wire counter to study natural radioactivity more than a century ago. Techniques for designing detectors of increased physical size and/or enhanced spatial resolution and sensitivity continue to be an active field of research in the detector community today.
Gaseous detectors typically collect the electrons released by ionizing radiation and guide them to a region with a strong electric field, thereby initiating an electron avalanche. The avalanche is able to produce enough electrons to create a current or charge large enough to be collected on a readout device and analyzed by readout electronics. The collected electron charge may indicate the charge, energy, momentum, direction of travel and other attributes of the incident particles or radiation.
In most such detectors, the large amplification field necessary to initiate and support the electron avalanche comes from a thin wire at a positive high voltage potential. This same thin wire also collects the electrons from the avalanche and guides them towards the readout electronics. More recently, attention has focused on so-called MicroPattern Gas Detectors (MPDGs) such as the Micromesh Gaseous Structure Chamber (MicroMegas) and the Gas Electron Multiplier (GEM). By employing semiconductor fabrication techniques, large area tracking MPGDs can be mass-produced in an impressive variety of geometries while at the same time permitting small avalanche gaps, and hence rapid signal development, fast readout and high reliability.
In MPGDs, the electrons generated in the amplification process are typically collected on metallic readout pads or strips that are arranged in a predetermined pattern on a semiconductor substrate and electrically connected to fast readout electronics. The spatial resolution of the detector device has conventionally been limited by the size of the individual readout pads. Two neighboring avalanches that are sufficiently close to hit a common readout pad can no longer be spatially distinguished, and hence may be misinterpreted as a single event.
An obvious way to increase the spatial detector resolution is to use more and smaller readout pads. However, a larger number of readout pads requires a correspondingly larger number of readout channels and electronics and hence increases both detector cost and complexity. In fact, the number of readout channels that can be analyzed quickly with modern readout electronics places an important constraint on the size of the readout pads, and hence on the detector resolution. This is particularly true as modern detectors become increasingly larger in size in order to accommodate for higher particle energies, and hence require a correspondingly large number of readout channels in the first place.
In an attempt to enhance the spatial resolution of the readout device without the drawback of a corresponding increase in the number of the readout channels, M. S. Dixit and A. Rankin propose, in their research article "Simulating the Charge Dispersion Phenomena in Micro Pattern Gas Detectors with a Resistive Anode", NUCL. INSTR. METH. A 566 (2006) 281, a composite anode readout pad with a resistive foil bonded to a plurality of readout pads with an insulating layer of glue. The glue acts as a dielectric spacer separating the resistive foil from the readout pads. Any localized charge avalanche arriving at the resistive foil will be dispersed in a direction parallel to the detector surface, and will induce corresponding charges in the subjacent readout pads. The relative intensity of the signals collected at neighboring readout pads allows to infer the position at which the cascade hit the resistive foil.
Another readout electrode assembly in which the spatial resolution is enhanced by means of a resistive charge spreading pad capacitively coupled to a plurality of readout boards is described in International Patent Application PCT/EP2009/000995. Careful calibration of the readout pads and a suitable interpolation scheme allow to localize events at a spatial resolution which is no longer limited to the size of an individual readout pad.
A charge spreading between readout pads mediated through a resistive material may lead to an increase in detector resolution. However, since the dispersion of the charges in the resistive layer needs time, this results in an indesirable increase in detector dead times and a corresponding reduction in readout rates.
Overview of the Present Invention
It is hence an object of the present invention to provide a readout device for an avalanche particle detector that allows for an improved resolution and faster readout. This objective is achieved by a readout device with the features of independent claim 1. The dependent claims relate to preferred embodiments.
A readout device for an avalanche particle detector according to the present invention comprises a first detector layer being defined by a first plurality of detector pads, and a second detector layer extending above said first detector layer, said second detector layer being defined by a second plurality of detector pads and being spatially separated from said first detector layer and being capacitively coupled thereto. The number of detector pads in said second detector layer is larger than the number of detector pads in said first detector layer. Said detector pads of said first detector layer are each connected to a readout means, said readout means being adapted to at least approximately determine a charge distribution among the detector pads of said second detector layer from a measured charge distribution among the detector pads of said first detector layer.
The detector concept according to the present invention relies on capacitive charge spreading through the readout board. An electron cloud hitting the front side of the readout board will induce a charge distribution on a plurality of detector pads in the second (upper) detector layer. The detector pads of the second detector layer may be spatially separated from the detector pads of the first detector layer extending beneath the second detector layer, but capacitively coupled thereto. Hence, the signal will spread in a downward direction to said detector pads of said first detector layer, from which it can be read out and analyzed. The readout means are adapted to at least approximately determine the charge distribution among the detector pads of the upper detector layer from the charge distribution measured among the detector pads of the lower detector layer. This allows to localize the position of the electron cloud hitting the front side of the detector from the signals detected at the bottommost detector layer opposite to the front side of the detector.
Since the number of detector pads in said second detector layer is larger than the number of detector pads in said first detector layer, the position of the incident particles can be determined with high accuracy even though only a relatively small number of readout pads in said first detector layer (and hence a corresponding small number of readout channels and electronics) is required. This reduces the cost and overall complexity of the readout system, and will enable readout boards of enlarged physical size and enhanced spatial resolution. Since capacitive spreading is fast, readout rates are high and detector times are short.
The principles underlying the present invention can be praciticed in a large variety of different detector designs. According to the invention, said first and second plurality of detector pads can be of any suitable shape, size and material, and can be arranged in any spatial configuration as long as the above-mentioned criterion is met. Any configuration or ensemble of said first plurality of detector pads defines a first detector layer in the sense of the present invention, and any further configuration or ensemble of said second plurality of detector pads defines a second detector layer. Said first and second detector layers can be of any size or shape, and may be either plane or curved.
According to a preferred embodiment of the invention, said detector pads are positioned in said respective detector layers such that a first charge distribution induced in said detector pads of said detector layer by a charge located on a given detector pad of said second detector layer is different from a second charge distribution induced in said detector pads of said first detector layer by an identical charge located on any neighboring detector pad of said given detector pad in said second detector layer. According to this embodiment, the detector pads shall be adapted and positioned in said first and second detector layers such that the charge distribution induced in said detector pads of said first (lower) detector layer allows to unambiguously infer the charge distribution in the second (upper) detector layer. For this purpose, according to the invention, said detector pads are positioned in said respective detector layers such that a first charge distribution induced in said detector pads of said first detector layer by a test charge located on a given detector pad of said second detector layer is different from a second charge distribution induced in said detector pads of said first detector layer by the same test charge on any other detector pad of said second detector layer. As long as this condition is met, it is indeed possible to trace back the charge distribution in the second (upper) detector layer from the readout charge distribution of the first (lower) detector layer, even if the number of detector pads in the second detector layer is larger than the number of detector pads in the first detector layer, or, in other words, the geometrical resolution of the second detector layer is higher than that of the first detector layer.
According to a preferred embodiment, the above-mentioned "second charge distribution" differs from said "first charge distribution" in that the relative amount of charges induced on two detector pads of said first detector layer according to said first charge distribution is different from the relative amount of charges induced on the same two detector pads of said first detector layer according to said second distribution. By comparing the charges that have spread to neighboring detection pads, the position of the impact can be determined accurately at a precision which is not limited by the size of the first detector pads.
According to a further embodiment, said second charge distribution differs from said first charge distribution in that it induces charges on a different set of detector pads of said first detector layer.
Preferably, said detector pads may be positioned in said respective detector layers such that said first charge distribution induces a charge exceeding a predetermined detection threshold on a given detector pad of said first layer, while said second charge distribution does not induce a charge above said detection threshold on that same detector pad of said first layer. Determining whether or not the charge induced on said detector pad is above or below said threshold value hence allows to distinguish said first charge distribution from said second charge distribution.
In a preferred embodiment of the present invention, a first set of detector pads of said first detector layer that a given pad of said second detector layer overlaps with is different from the set of detector pads of said first detector layer that any neighboring detector pad of said given detector pad in said second detector layer overlaps with. Since neighboring detector pads of said first layer may differ in the degree of overlap with the detector pads of said second detector layer, the charge distributions induced in said detector pads of said first detector layer may differ correspondingly. This allows to infer the position of the impact by comparing the relative amount of charges on the readout pads of said first detector layer.
In the sense of this invention, a detector pad of said first detector layer and a detector pad of said second detector layer may be understood to overlap if their projections, for instance their orthogonal projections, onto a common plane along a direction normal to said detector layers intersect. The size of the intersection may be indicative of the degree of the overlap. The set of detector pads of said first detector layer that a given detector pad of said second detector layer overlaps with may be the ensemble of detector pads of said first detector layer that has a non-vanishing overlap with a given detector pad of said second detector layer, when projected onto a common plane. The amount of the overlap of a detector pad of said first detector layer with a detector pad of said second detector layer may determine the amount of the charges induced in said detector pad of said first detector layer by a charge located on said detector pad of said second detector layer.
According to a preferred embodiment, a ratio of an overlap of a detector pad of the second detector layer with a first and a second detector pad of said first detector layer, respectively, is different from a ratio of an overlap of any neighboring detector pad of said given detector pad in said second detector layer with said first and said second detector pad in said first detector layer, respectively.
Since the degree or proportion to which the neighboring detector pads of said second layer overlap with a given pair of detector pads of said first detector layer vary, the charge distributions induced in said detector pads of said first detector layer vary accordingly. Again, this allows to infer on which of the two detector pads of the second detector layer a charge is located.
According to a further embodiment of the present invention, said detector pads in said second detector layer are smaller than said detector pads in said first detector layer. Despite the relatively large size of the readout pads of said first detector layer, capacitive charge spreading allows to localize the event with enhanced precision. In particular, the spatial resolution of the readout device according to the present invention is not limited by the relatively large size of the detector pads in said first detector layer. By comparing the charges that have spread to neighboring detector pads, the readout device according to the present invention allows to localize the position of the impact with high precision by reading out only a relatively small number of large readout pads of said first detector layer instead of the larger number of small readout pads of said second detector layer.
According to a preferred embodiment, said detector pads in said second detector layer are three to six times smaller in surface area, preferably four to five times smaller in surface area than said detector pads in said first detector layer.
According to a further preferred embodiment, said detector pads are equidistantly spaced in said first detector layer and/or in said second detector layer.
Said first detector layer may be separated from said second detector layer by a first dielectric layer. The dielectric layer may serve to provide the capacitive coupling between neighboring detector pads. In a preferred embodiment, a thickness of said first dielectric layer is in a range of 10 μm to 500 μM.
In a further preferred embodiment, a size and/or an orientation of said detector pads and/or a thickness and/or a material of a first dielectric layer separating said first detector layer from said second detector layer are chosen such that a capacitance formed by a detector pad in said first detector layer and an overlapping detector pad formed in said second detector layer is in the range of 10 pFarad per cm2 and 1 nFarad per cm2.
According to a further embodiment, a size and/or an orientation of said detector pads and/or a thickness and/or a material of the first dielectric layer separating said first detector layer from said second detector layer are chosen such that a capacitance formed by a detector pad in said first detector layer and an overlapping detector pad formed in said second detector layer is at least five times larger, and preferably at least ten times larger, than a capacitance formed by said first detector pad and its neighboring detector pad in said first layer.
By choosing the capacitive coupling in a lateral direction sufficiently smaller than the capacitive coupling in the vertical direction, an undesirable spreading of the signal in the lateral plane, which might otherwise dilute the signal, can be avoided.
According to a preferred embodiment, a size and/or an orientation of said detector pads and/or a separation of neighboring detector pads within said first detector layer and/or within said second detector layer is chosen such that a capacitance formed by said neighboring detector pads is in the range of 2.5 fFarad to 250 fFarad.
The readout device according to the present invention is not limited to two detector layers, but may comprise any number of successive detector layers defined by corresponding pluralities of detector pads. The signal will then spread through the subsequent layers by means of capacitive coupling until it reaches the bottommost layer, from which the signal is read out and analyzed. The larger the number of subsequent detector layers, the less readout channels may be required, and the higher is the spatial resolution of the detector device.
The readout device according to a preferred embodiment further comprises a third detector layer extending above said second detector layer, said third detector layer being defined by a third plurality of detector pads and being spatially separated from said second detector layer, but capacitively coupled thereto, wherein the number of detector pads in said third detector layer is larger than the number of detector pads in said second detector layer.
Hence, charges may be spread by means of capacitive coupling from said third detector layer to said second detector layer in exactly the same way as described above for the second and first detector layers, respectively. Once charges have been induced on said detector pads of said second detector layer, they will in turn induce corresponding charges on said detector pads of said first detector layer in exactly the same way described with reference to the preceding embodiments. Once charges are induced on said detector pads of said first detector layer, they can be read out and analyzed by means of the readout electronics. Since the number of detector pads in the third detector layer is still larger than the number of detector pads in the second detector layer, the spatial resolution of the detector device can be further enhanced even though the number of readout pads (and hence readout channels and readout electronics) is conserved.
According to a preferred embodiment, said detector pads are positioned in said third detector layer such that a first charge distribution induced in said detector pads of said second detector layer by a charge located on a given detector pad of said third detector layer is different from a second charge distribution generated in said detector pads of said second detector layer by an identical charge located on any neighboring detector pad of said given detector pad in said third detector layer
This allows to unambiguously determine the charge distribution in the third detector layer from the charge distribution in the second detector layer, which can in turn be determined from the charge distribution measured in the readout pads of the first detector layer.
According to a preferred embodiment, said second charge distribution may differ from said first charge distribution in that the relative amount of charges induced on two detector pads of said second detector layer according to said first charge distribution is different from the relative amount of charges induced on the same two detector pads of said second detector layer according to said second charge distribution.
In a preferred embodiment, a first set of detector pads of said second detector layer that a given detector pad of said third detector layer overlaps with is different from the set of detector pads of said second detector layer that any neighboring detector pad of said given detector pad in said third detector layer overlaps with. As described above, whether and to which extent a detector pad of said third detector layer and a detector pad of said second detector layer overlap with each other, when viewed along a direction normal to said second and third detector layers, may determine the degree of capacitive coupling between said pair of detector pads, which in turn determines the relative amount of charges spreading to neighboring detector pads.
According to a further embodiment, said detector pads in said third detector layer are smaller than said detector pads in said second detector layer.
According to a preferred embodiment, said detector pads in said third detector layer are three to six times smaller in surface area, preferably four to five times smaller in surface area than said detector pads in said second detector layer.
Since charges are subsequently induced in subsequent detector layers, the readout device according to the present invention allows for an increase in spatial resolution, or a decrease in the number of readout channels required, that scales exponentially in the number of detector layers. The ratio in surface area of detector pads of consecutive layers determines the basis for the exponential scaling.
According to a preferred embodiment, said third detector layer is separated from said second detector layer by a second dielectric layer. A thickness of said second dielectric layer may be in a range of 10 μm to 500 μm.
According to a preferred embodiment, said detector pads are equidistantly spaced in said third detector layer.
In a preferred embodiment, the readout device further comprises a resistive layer formed at an upper surface of said readout device, said resistive layer being separated from the uppermost detector layer by a third dielectric layer.
The resistive layer may serve to protect the readout device from sparks or discharges, while at the same time allowing a dispersion of charges induced by the arriving electrons in the lateral direction.
According to a preferred embodiment, a surface resistivity of said resistive layer for charge transport in a direction parallel to said upper surface of said readout device is in a range of 0,5 MOhms per square to 100 MOhms per square. A surface resistivity in this range efficiently protects against sparks. At the same time, it prevents the signal from spreading over a distance that would exceed one detector pad diameter in the subjacent detector layer, and might therefore reduce the spatial resolution of the detector device.
In a preferred embodiment of the present invention, said detector pads of said first detector layer, said second detector layer and said third detector layer are all embedded into a common holding structure formed of a dielectric. A common holding structure allows for a convenient and simplified manufacturing process.
In a further preferred embodiment, said detector pads of said first detector layer and/or said detector pads of said second detector layer and/or said detector pads of said third detector layer are formed of copper.
The present invention is also directed at an avalanche particle detector comprising a gas chamber and first, second and third electrodes placed in this order in said gas chamber, wherein said first electrode and said second electrode delimit a conversion gap for generation of electrons by incident particles, and wherein said second electrode and said third electrode delimit an amplification gap for multiplication of electrons in an avalanche process. The second electrode is perforated by holes, and the third electrode comprises a readout device with some or all of the features of the present invention as described above.
The second perforated electrode and the third (readout) electrode may be connected to polarization means for generation of a high electric field in the amplification gap. Electrons are generated in this gap and then drift towards the third electrode where they produce a final electron charge to be localized with the readout device according to the present invention. As described above, capacitive spreading of the electron charge through the subsequent detector layers allows to detect the position of the impact with enhanced precision while requiring only a very limited number of readout channels.
The present invention is further directed at an avalanche particle detector comprising a gas chamber and first and second electrodes placed in this order in said gas chamber. Said first electrode comprises an insulator having first and second metal coating layers on opposed surface sides thereof, and a plurality of holes extending through said first electrode. The detector further comprises polarization means coupled to said coating layers and adapted to raise said first coating layer to a first potential and to raise said second coating layer to a second potential higher than said first potential. Said second electrode comprises a readout device according to the present invention with some or all of the features discussed above.
According to this latter embodiment, electron multiplication may take place in a plurality of holes extending through a foil with metal coatings on both sides. The generated electrons may then drift to the readout device, which is not involved in the amplification process itself Also, in this second detector design, the readout device according to the present invention allows to localize the event with enhanced spatial resolution and/or with a reduced number of readout pads.
FIG. 1 is a side view of a part of a capacitive spreading readout board 10 according to the present invention. The readout board 10 shown in FIG. 1 comprises a plurality of detector pads 12 formed of copper and embedded into a common holding structure 14. The detector pads 12 are formed in said holding structure 14 to define (along a Z direction) three consecutive detector layers 16, 18, 20, each comprising a plurality of spatially separated detector pads 12. The detector pads 121 forming the bottommost (first) detector layer 16 are smallest in number, but largest in size. They are formed of flat cuboids with a quadratic surface area and an edge length of approximately 2 mm and a thickness of approximately 10 μm. In the schematic drawing of FIG. 1, only two detector pads 121 of the first detector layer 16 are shown. However, a capacitive spreading readout board 10 according to the present invention may comprise any number of detector pads 121 in the first detector layer 16. Each of the detector pads 121 of the first detector layer 16 are connected to individual readout means 22, which are in turn connected to readout electronics (not shown) for analysis of the signals triggered by incident particles or radiation.
The detector pads 122 forming the second detector layer 18 extend above the detector pads 121 of the first detector layer 16, and are separated from the first detector layer 16 by a first dielectric layer 24 formed of Prepreg, a glass epoxy, at a thickness of approximately 75 μm and having a dielectric constant ε in the range of 3.5 to 4.5. The detector pads 122 of the second detector layer are again formed of copper and are cuboid in shape with a quadratic surface area and an edge length of approximately 1 mm and a thickness of approximately 10 μm. The schematic drawing of FIG. 1 shows five detector pads 122 in the second detector layer 18, but it is to be understood that a readout board 10 according to the present invention may comprise any number of detector pads 122 in the second detector layer 18.
The detector pads 123 extend above the second detector layer 18 and define the third detector layer 20, which is separated from the second detector layer 18 by a second dielectric layer 26. The detector pads 123 of the third detector layer are formed of copper and are cuboid in shape with a quadratic surface area and an edge length of approximately 0.5 mm and a thickness of approximately 10 μm. In the embodiment depicted in FIG. 1, the second dielectric layer 26 is identical in thickness and material to the first dielectric layer 24, but depending on the application it may also be advantageous to form the first dielectric layer 24 and the second dielectric layer 26 of different materials, and/or with different thicknesses.
In contrast to the detector pads 121 of the first detector layer 16, neither the detector pads 122 of the second detector layer 18 nor the detector pads 123 of the third detector layer 20 are connected to readout means. Instead, they are electrically isolated in said dielectric holding structure 14.
The readout board 10 illustrated in FIG. 1 further comprises a resistive cover layer 28 formed at a top surface of the readout board 10 and separated from the third detector layer 20 by a third dielectric layer 30. In the embodiment of FIG. 1, the third dielectric layer 30 is identical in material and thickness to the first and second dielectric layers 24, 26. However, depending on the detector layout the third dielectric layer 30 may also be formed of a material, or size different from the material and size of the first and/or second dielectric layers 24, 26, respectively.
The inventors found that the material and dimensions of the resistive cover layer 28 may be adjusted such that its surface resistivity provides efficient protection of the readout board 10 against sparks and discharges while at the same time preventing horizontal spreading of the signal along the resistive cover layer 28 over a range that corresponds to more than one pad size in the underlying first detector layer 20.
The surface resistivity or sheet resistivity RS of a rectangular block of uniform material with a height h, a length l and a width w is generally given by p/h, where p is the specific resistance of the material. The total resistance R for charge transport along the length l of the substrate is then given in terms of the surface resistivity RS as
  R  =                    R        S            ·              l        w              =                  ρ        h            ·                        l          w                .            In the readout board according to the present embodiment, the resistive cover layer 28 has a quadratic surface area. Hence, l=w, and the resistance R for charge transport in a direction parallel to the upper surface of the readout board 10 therefore equals the sheet resistivity RS, i.e. R=RS. In order to better distinguish surface resistivity from total resistance, surface resistivity is usually measured in the units Ohm per square.
In the embodiment illustrated in FIG. 1, the resistive cover layer 28 is formed from a high resistive polyimide at a thickness of approximately 25 μm and with a surface resistivity for charge transport along a direction parallel to the upper surface (perpendicular to the Z direction) of the readout board 10 in the range of 0.5 to 100 MOhms per square.
In the embodiment depicted in FIG. 1, the detector pads of a given layer are all identical in size, shape, and material, and are distributed within their given layer at a separation of roughly 50 μm between neighboring pads. However, it is one of the advantages of micropattern gas detectors that detector pads can be formed in a large variety of different shapes and configurations, including two-dimensional strips, hexagonal pads, radial segments, and other geometries, depending on the detector design and operating conditions. Examples of readout geometries are described in A. Bresson et al., "Two-Dimensional Readout of GEM Detectors", Nuclear Instruments and Methods in Physics Research A 425 (1999) 254-261, which is incorporated herein by reference.
Moreover, the detector pads 12 according to the embodiment of FIG. 1 are arranged in plane layers 16, 18, 20 formed at equal intervals in said holding structure 14. However, the present invention is not limited to plane layers. Depending on the detector geometry and operation, the detector pads 12 may also be arranged to form bended or curved layers. For instance, the detector pads 12 of subsequent layers may be distributed equidistantly on concentrical spherical shells. The resistive cover layer 28 may likewise be formed in any (plane or curved) shape.
The layout and configuration of the detector pads 12 as well as their relevance for the capacitive charge spreading will now be described in greater detail with reference to FIG. 2. FIG. 2 may be taken as a schematic plan view of the readout board 10 as illustrated in FIG. 1. However, for ease of presentation the simplified illustration of FIG. 2 shows only two adjacent detector layers, namely the first detector layer 16 and the second detector layer 18. The detector pads of the third detector layer 20 and the resistive cover layer 28 are not shown in FIG. 2 in order not to obscure the illustration. However, in the embodiment depicted in FIG. 1, the configuration of the detector pads 123 of the third detector layer 20 with respect to the detector pads 122 of the second detector layer 18 is the same (but for a rescaling of the detector pads) as the configuration of the detector pads 122 of the second detector layer 18 with respect to the detector pads 121 of the first detector layer 16. Hence, the plan view of FIG. 2 could equally well be taken to show the second detector layer 18 and third detector layer 20 instead of the first detector layer 16 and second detector layer 18, respectively.
In the plan view of FIG. 2, the detector pads 121 of the first detector layer 16 are each represented by a large square (wherein the pads 121 along the periphery are only partially drawn, since FIG. 2 is a cut-away view of the readout board 10), while the detector pads 122 of the second detector layer 18 extending above the first detector layer 16 are represented by smaller squares. Each detector pad 122 of said second detector layer 18 is positioned to overlap with a specific set of detector pads 121 of said first detector layer 16, when viewed along the direction Z perpendicular to the common plane of the first detector layer 16 and second detector layer 18. For instance, the detector pad a in the center of the second detector layer 18 overlaps with the detector pads A and B of the first detector layer 16, while the detector pad b of the second detector layer 18, positioned to the immediate right of the detector pad a, overlaps with detector pad B of the first detector layer 16 only. Detector pad c of the second detector layer 18 overlaps with detector pads B and C of the first detector layer 16, while detector pad d of the second detector layer 18 overlaps with each of detector pads A, B, C and D of the first detector layer 16. The degree or proportion to which the respective detector pads overlap may also vary. For instance, detector pad a overlaps to equal proportions with A and B, while detector pad c overlaps with B and C such that approximately two thirds of the surface area of c lie above B and approximately one third of the surface areas of c lie above C.
As can be taken from the illustration of FIG. 2, the detector pads 12 are arranged in said first and second detector layers 16, 18 such that the set of detector pads 121 of the first detector layer 16 that a given detector pads 122 of the second detector layer 18 overlaps with is unique to each detector pad 122. By means of capacitive coupling between the subsequent layers, electrical charges induced on the given detector pad 122 of the second detector layer 18 will hence induce a charge distribution on the detector pads 121 of the underlying first detector layer 16 that is unique to the detector pad 122. For instance, a charge located on the detector pad a of the second detector layer 18 will induce approximately equal charges on detector pads A and B of the first detector layer 16, while a corresponding charge on detector pad b of the second detector layer 18 will, to a very good approximation, induce a charge on detector pad B of the first detector layer 16 only. Hence, the relative amount of charges induced on the detector pads 121 of the first detector layer 16 allows to identify on which detector pad/pads of the second detector layer 18 charges were induced, and hence allows to locate the origin of the charge.
In a completely analogous way, a charge located on a given detector pad 123 of the third detector layer 20 will induce a corresponding charge distribution on the detector pads 122 of the second detector layer 18 that is unique to that detector pad 123. Hence, the relative amount of charges induced on the detector pads 122 of the second detector layer 18 allow to identify the detector pad 123 of the third detector layer 20 from which the charge signal originated.
The direction and speed at which charges spread through the subsequent detector layers 16, 18, and 20 of the readout board 10 are determined by the capacitive coupling between neighboring detector pads, which is in turn governed by the geometry and size of the detector pads 12 as well as by the dielectric material separating neighboring pads. If the capacitive coupling between neighboring pads in the same detector layer is too high, the signal will propagate in a lateral direction (perpendicular to the Z direction) and will be diluted over much of the detector surface before reaching the bottommost layer. The signal level may then be too low for reliable signal detection. Hence, the parasitic capacitance in the lateral direction limits the number of subsequent detector layers over which a signal may reliably spread. The inventors found that signals can be reliably localized over three or even four subsequent detector layers if a size and/or an orientation of the detector pads and/or a thickness and/or a material of the dielectric layer separating two adjacent detector layers are chosen such that a capacitance formed by a detector pad in said first layer and an overlapping detector pad formed in said second layer is at least five times larger, and preferably at least ten times larger, than a capacitance formed by neighboring detector pads within the same detector layer.
In the embodiment depicted in FIGS. 1 and 2, a size and/or an orientation of the detector pads 12 are chosen such that a capacitance formed by neighboring detector pads in one and the same layer is in a range of 5 fFarad to 250 fFarad, while a capacitance between overlapping detector pads in adjacent layers is in the range of 10 pFarad per cm2 to 1 nFarad per cm2.
Next, the operation of the readout board 10 for the detection of particles or radiation will be described in further detail.
An incident particle penetrating the particle detector will generate an electron cloud hitting the resistive cover layer 28 of the grounded readout board 10. As explained above, the readout board 28 serves to protect the readout board 10 from sparks and discharges and disperses the electron charge over part of the detector surface. A high surface resistivity in the range of 30 MOhms per square to 100 MOhms per square efficiently prevents lateral spreading of the signal over an area larger than the surface of one pad in the uppermost detector layer, which would reduce the spatial resolution.
By means of capacitive coupling mediated through the third dielectric layer 30, charges are induced on the detector pad 123 that corresponds in position to the location at which the electron cloud hit the resistive cover layer 28. As described above with respect to FIGS. 1 and 2, the charge induced on this detector pad 123 itself induces charges on the detector pads 122 of the underlying second detector layer 18 by means of capacitive coupling via the second dielectric layer 28, which in turn induce further charges on the detector pads 121 of the first detector layer 16 by means of capacitive coupling via the first dielectric layer 24. Hence, charge signals are spread downwardly (along the Z direction) through the detector body. The charges induced on the detector pads 121 of the first detector layer 16 are then read out and analyzed by means of the readout means 22.
As described above, the relative amount of charges detected on the detector pads 121 of the first detector layer 16 allows to infer which of the detector pads 123 of the third detector layer 20 was initially triggered, and may hence permit to determine the position of the electron cloud with great accuracy by comparing the charges that have spread to neighboring readout pads. In particular, the position of the electron cloud can be determined at an accuracy that corresponds roughly to the size of one of the small detector pads 123 of the uppermost layer 20, even though only the significantly larger detector pads 121 of the first detector layer 16 are readout and analyzed.
As a result, the invention provides a high resolution readout board with a reduced number of readout channels. The increase in detector resolution, or the decrease in the number of readout channels depends on the number of different detector layers and on the relative size of the readout pads in subsequent layers. The readout board 10 according to the present embodiment has three subsequent layers 16, 18, 20 of detector pads. A detector pad 122 of the second detector layer 18 has a surface size that is approximately four times the surface size of a detector pad 123 of the third detector layer 20, and the same relation holds for the detector pads 121 and 122 of the first and second detector layers 16 and 18, respectively. Hence, the readout board 10 according to the present embodiment allows for an increase in surface resolution, or a decrease in the number of readout channels by a factor of 42. More generally, a readout board 10 with n subsequent detector layers and a surface ratio r between the surface size of detector pads of two subsequent layers allows for an increase in spatial resolution, or a decrease in the number of readout channels by a factor of approximately rn-1.
The operation of a readout board 10 according to the present invention will now be illustrated in further detail by way of example for a gas electron multiplier detector (GEM) such as the one known from U.S. Pat. No. 6,011,265, on which FIG. 3 is based.
The GEM detector 32 depicted in FIG. 3 comprises a gas chamber (not shown, otherwise referred to herein as a gas enclosure) provided with means for circulating an appropriate gas, for example a mixture or of argon and methane. The detector 32 further comprises an inlet window 34, through which ionizing particles or radiation may enter the gas enclosure, as well as three plane electrodes 36, 38 and 10 placed in this order in the gas enclosure parallel to one another. The upper electrode 36 serves as a drift electrode and is raised to a drift potential VD. The lower electrode 10 comprises a readout board according to the present invention including first, second and third detector layers 16, 18, 20 embedded into a common holding structure 14, as described above with reference to FIGS. 1 and 2.
The intermediate electrode 38 is a so-called GEM electrode and comprises an insulator foil 40 sandwiched between a first metal coating layer 42 and a second metal coating layer 44. Polarization means 46 are coupled to the first metal coating layer 42 and the second metal coating layer 44 to apply a high potential VGEM therebetween, and small cylindrical holes 48 are formed at regular intervals in the GEM electrodes 38 to extend through the first metal coating layer 42, insulator foil 40, and second metal coating layer 44.
When an ionizing particle passes through the gas chamber, it ionizes the gas located in the drift zone between the drift electrode 36 and the GEM electrode 38 and typically creates about ten primary electrons in that gap. Those electrons are then drawn towards the GEM electrode 38 by the drift field extending between the drift electrode 36 and the GEM electrode 38. The voltage VD applied to the drift electrode 36 and the voltage VGEM applied to the metal coating layers 42, 44 are selected such that the electric field generated inside the cylindrical holes 48 is much stronger, for example more than 20-50 times stronger, than the electric field in the drift space. Due to this large field gradient, the primary electrons approaching the GEM electrode 38 are drawn into the cylindrical holes 48 and accelerated to sufficiently large speeds to induce an avalanche multiplication within the cylindrical holes 48.
The positive ions created by the impact ionization process are drawn towards the drift electrode 36, while the electron cloud is accelerated in the opposite direction and towards the readout board 10 until it hits the resistive cover layer 28. As described above, the electron cloud will then induce a charge on one of the detector pads 123 of the third (uppermost) detector layer 20. By means of capacitive coupling, the signal will spread via the second detector layer 18 to the first detector layer 16, from which it will be read out and analyzed to infer the attributes of the incident particles. The readout means 22 connected to the detector pads 121 of the first detector layer 16 comprise both fast amplifiers A that amplify the electric signals collected by the readout board 10, and processing means (not shown) for processing the signals supplied by the fast amplifiers A. For ease of presentation, only two readout means 22 are shown in the illustration of FIG. 3. However, it is to be understood that each of the detector pads 121 of the first detector layer 16 is connected to a corresponding readout and processing means. As explained above, the position of the impact of the electrode cloud can be determined by comparing the charges that have spread to neighboring readout pads 121, and hence the incident particle can be localized at high precision despite the relative large size of the readout pads 121.
The readout board 10 according to the present invention is by no means limited to the GEM detector described above with reference to FIG. 3 above, but may be applied to the same effect in a variety of other particle detectors, in particular micropattern gaseous detectors. For instance, the readout board 10 according to the present invention may also serve as an anode of a MicroMegas detector such as the one described in U.S. Pat. No. 6,133,575, and will likewise permit the localization of incident particles at a higher precision or with a smaller number of readout channels.
The embodiments described above as well as the accompanying figures merely serve to illustrate the readout board and particle detectors according to the present invention, and should not be taken to indicate any limitation. The scope of the patent is solely determined by the following claims.

CERN-European Organization for Nuclear Research


The present invention provides a method and a device for synchronously collecting fingerprint information. By setting a fingerprint recognition area on a display unit of a terminal, and placing a sensing unit below the fingerprint recognition area to receive a sliding track of the user's finger on the display unit and, when the user's finger slides to the fingerprint recognition area, to synchronously collect fingerprint information corresponding to the user's finger, thereby synchronously collecting the user's sliding track information (such as an electronic signature) and the user's fingerprint information, and effectively reducing the user's operation steps and improving user's experience.

With the development of science and advances in technology, touch display panels have been widely used in devices that require human-computer interaction interfaces, such as operating screens of industrial computers, touch screens of tablet computers and smart phones, etc. As these devices are usually accompanied by a large amount of user information during use, the protection of user information security is particularly important. Among many methods of information security protection, fingerprint recognition encryption is an important one.
At the same time, electronic signatures have been widely used. For example, when a consumer uses a credit card for consumption, the merchant usually requires the consumer to sign the name for archival purposes, and the electronic signature has the characteristics of being easy to store and highly recognizable compared to the paper signature. However, in the prior art, the electronic signature and the fingerprint recognition are often independent, that is, when the user leaves his or her own electronic signature on the mobile terminal, the terminal cannot collect the user's fingerprint synchronously, and is not able to perform the fingerprint recognition operation. When the fingerprint is needed, the user's fingerprint needs to be collected again, which is cumbersome and brings a bad experience to the user.
In summary, it is particularly necessary to provide a solution for synchronously collecting user's fingerprint when the user performs electronic signature, so as to reduce the user's operation steps and improve user's experience.

Method and device for synchronously collecting fingerprint information


In a BIR type brake caliper according to the embodiment of the present invention, when a BIR (Ball in Ramp) type cartridge assembly, which generates an axial force while rotating, presses pads against a disk plate during parking braking, balls provided between input and output ramps of the cartridge assembly move along variable trajectories gradually decreased in a radial direction and increase a force. For this reason, even though an operation force of a parking lever is small, the cartridge assembly generates a force capable of maintaining a parking braking force. As a result, it is possible to obtain characteristic reducing an operation force, which should be applied to a parking handle by a driver.

In general, a parking brake, which is used to temporarily park a vehicle or park a vehicle on an inclined place such as a hill, applies pressure to a wheel by using cables pulled by a hand unlike a brake that applies pressure to a wheel by using oil pressure generated by a general pedal. The parking brake is operated by a parking lever provided near a driver's seat.
The parking brake includes a parking lever, a parking brake cable, and an equalizer. The parking lever is operated by a hand. The parking brake cables are pulled or loosened by a latch assembly (not shown) operated by a release knob, which is provided in the lever and releases the brake. The equalizer is provided between left and right cables connected to left and right rear wheels, and uniformly distributes an operation force.
The above-mentioned parking brake is generally locked by a strong contact force generated by pressing pads against a drum, which is provided in the wheel, with an operation force of the parking brake.
Further, a manner using a caliper for performing braking with a disk plate positioned between pads is also used instead of a manner pressing the pads against the drum. The caliper, which forms the parking brake and applies a braking force to the disk plate, is generally called a BIR caliper (Ball-In-Ramp Caliper).
As a parking brake using the BIR caliper is operated, an axial force is generated in the BIR caliper by a parking cable. That is, when a pulling force of the parking cable is changed into torque of a ramp and the positions of balls provided in the BIR caliper are changed, an increased axial force is generated at an opposite ramp due to the movement of the balls and pads are pressed against the disk plate due to the axial force. As a result, a parking braking force is generated.
However, the BIR caliper generates a parking braking force by using the ramp that generates an axial force along a movement trajectory of the ball according to the rotation of the ramp to which a parking braking is input. Accordingly, the BIR caliper should generate a parking braking force that is smaller than a braking force used to brake a driving car but is enough to restrict to the movement of the vehicle. For this reason, during parking braking, large initial input is needed to operate the BIR caliper.
A driver's operation unit, that is, a parking lever should be operated to have a large angle to increase the initial input used to operate the BIR caliper during parking braking. For this reason, there is a problem in that a driver's operation force is increased to perform parking braking.

Ball-in-ramp brake caliper type parking brake for vehicle


A laterally expandable spinal implant includes a central body and two wings that are adapted to be received within an inner chamber formed within the central body. The wings have guide rails that fit into grooves defined in the central body. To ensure that the implant is properly secured, each guide rail has an outer end with a cutting surface that cuts into vertebral end plates when the wings are extended. The two wings are connected together through a central turnbuckle shaft that has geared teeth and threading on both ends that engage threaded cavities in the wings. Through the gear teeth, the turnbuckle shaft is able to be rotated so as to laterally extend the wings from the central member. A locking mechanism locks the turnbuckle shaft to prevent the wings from retracting.

The present invention generally concerns spinal implants, and more specifically, but not exclusively, concerns a laterally expandable vertebral implant.
A major cause of persistent, often disabling, back pain can arise by disruption of the disc annulus, chronic inflammation of the disc, or relative instability of vertebral bodies surrounding a given disc, such as might occur due to a degenerative disease. In the more severe cases, some form of mechanical limitation to the movement of the vertebrae on either side of the subject disc is necessary. In such cases, the disc tissue is irreparably damaged, thereby necessitating removal of the entire disc. However, when the disc nucleus is removed without subsequent stabilization the same disabling back pain often reoccurs due to persistent inflammation and/or instability.
Various approaches have been developed to stabilize the adjacent vertebral bodies following excision of this material. In one approach, two adjacent vertebrae are fused together through a fusion device that is implanted between the vertebrae. Many of these existing implant designs have drawbacks that lower the spinal fusion rates. Among these design drawbacks, one such flaw is that the implants subside into the vertebral end plates, thereby reducing the spacing between the vertebral bodies. With prior fusion devices, and even some prosthetic devices, a large portion of the load is placed against the weakest part of the vertebral body, which can lead to cavitation of the device into the surrounding vertebral endplates with subsequent collapse of the inner discal space and even damage of the vertebrae itself. Another frequent cause for subsistence is created by having a small area of contact between the implant and the endplates. As one should appreciate, the less surface area of contact between the implant and the end plates, the greater the risk of subsistence.
Another flaw of many implants is the lack of stability created after implantation. Stability is crucial to the success of a fusion. The implant must be securely fixated to the vertebral bodies in order to ensure that no movement occurs between the two. If movement does occur between the vertebral bodies and the implant, the bone may not properly fuse, thereby creating stability problems. Moreover, some designs limit the amount of graft material, which may be able to be used with the implant. The larger area of graft material that is able to contact the endplates, the better chances of a good, solid bone growth between the two vertebrae.
Some designs have created implants in which the majority of the implant is positioned over the harder cortical bone of the apophyseal ring of the vertebrae in order to reduce the chances of subsistence. However, with these designs, the implant is made from multiple separate components that are individually assembled together within the disc space. Each component is implanted separately and then attached to one another within the disc space. As should be appreciated, assembling such an implant in the disc space can be rather difficult. Such implants also tend to lack a stiff central body, which is essential to the stability of the implant as well as entire fusion construct. Moreover, such implants have no mechanism to fix the implant to the vertebral body. Typically, one has to use bone screws to secure the implant to the vertebral bodies, which makes the implantation process more complicated and difficult. In addition, such implants generally have a single lateral width, and therefore, it is generally very difficult, if not impossible, to adjust for differently sized vertebrae. Another flaw is that these designs typically do not provide a mechanism for ensuring that the spacers are properly positioned. Since the lateral spacers of these types of implants are independently assembled within the disc space, the lateral members can be positioned at unequal positions along the apophyseal ring, thereby increasing the risk that the implant will subside into the vertebral end plates.
In one aspect, a spinal implant includes a cage defining an interior cavity and an expansion mechanism received in the cavity of the cage. A pair of wings are operatively coupled to the expansion mechanism, and the wings each have opposing vertebrae engaging surfaces that are configured to engage opposing vertebrae. The expansion mechanism is operable to laterally move the wings between the vertebrae from a compact configuration in which at least a majority of the wings are received in the cavity of the cage to an expanded configuration in which the wings extend from the cage with the vertebrae engaging surfaces on each of the wings engaging the vertebrae.
Another aspect concerns a fusion device for implanting between opposing vertebrae that define a disc space. The device includes a central member and at least one pair of lateral members slidably coupled to the central member. The device further includes means for extending the lateral members from the central member into the disc space between the vertebrae with each of the lateral members engaging both of the vertebrae.
In a further aspect, an apparatus includes a spinal implant. The spinal implant includes a central member defining an interior cavity and a pair of openings defined on opposite sides of the central member that open into the interior cavity. A pair of wings are slidably received in the openings in the central member. A shaft is coupled to the wings, and the shaft has at least one threaded portion threadedly engaging at least one of the wings.


The method for forming a semiconductor structure includes first providing a substrate. Then, a TiN layer is formed on the substrate at a rate between 0.3 and 0.8 angstrom/second. Finally, a poly-silicon layer is formed directly on the TiN layer. Since the TiN in the barrier layer is formed at a low rate so as to obtain a good quality, the defects in the TiN layer or the defects on the above layer, such as gate dummy layer or gate cap layer, can be avoided.

1. Field of the Invention
The present invention relates to a method for forming a semiconductor structure, and more particularly, to a method for forming a semiconductor structure having a MOS with a TiN layer as the barrier layer.
2. Description of the Prior Art
In modern society, the micro-processor systems comprising integrated circuits (IC) are ubiquitous devices, which are utilized in diverse fields such as automatic control electronics, mobile communication devices and personal computers. With the development of technologies and the increasingly imaginative applications of the electrical products, the IC devices become smaller, more delicate and more diversified.
Metal-oxide-semiconductors (MOS) transistors are usually used in the integrated circuits. Conventionally, a poly-silicon layer is used as the gate material of the MOS. However, with a trend toward scaling down the size of semiconductor devices, conventional poly-silicon gates face problems such as inferior performances due to boron penetration and unavoidable depletion effect, which increases the equivalent thickness of the gate dielectric layer, reduces the gate capacitance, and worsens a driving force of the devices. Therefore, metals with a work function that are suitable for use as the high-k gate dielectric layer, are used to replace the conventional poly-silicon gates to serve as the control electrode.
However, some issues still need to be overcome in the current metal gate MOS fabrication method.

Method for forming semiconductor structure having TiN layer