A method and system increase the quality of results achieved by laser micromachining systems. Data relating to parameters controlling laser micromachining process are recorded during the micromachining process, identified by the feature associated with the parameters used to micromachine, and stored on the system. The stored data can be either retrieved during the micromachining process to enable real time control or retrieved after workpiece processing to conduct statistical process control.

Laser processing can be conducted on numerous different workpieces using various lasers effecting a variety of processes. The specific types of laser processing of interest with regard to the present invention are laser processing of a single or multilayer workpiece to effect hole and/or blind via formation and laser processing of a semiconductor wafer to effect wafer dicing or drilling. The laser processing methods described herein could also be applied to any type of laser micromachining, including but not limited to removal of semiconductor links (fuses) and thermal annealing or trimming passive thick or thin film components.
Regarding laser processing of vias and/or holes in a multilayer workpiece, U.S. Pat. Nos. 5,593,606 and 5,841,099 of Owen et al. describe methods of operating an ultraviolet (UV) laser system to generate laser output pulses characterized by pulse parameters set to form in a multilayer device through-hole or blind vias in two or more layers of different material types. The laser system includes a nonexcimer laser that emits, at pulse repetition rates of greater than 200 Hz, laser output pulses having temporal pulse widths of less than 100 ns, spot areas having diameters of less than 100 μm, and average intensities or irradiance of greater than 100 mW over the spot area. The preferred nonexcimer UV laser identified is a diode-pumped, solid-state (DPSS) laser.
U.S. Patent Application Publication No. US/2002/0185474 of Dunsky et al. describes a method of operating a pulsed CO2 laser system to generate laser output pulses that form blind vias in a dielectric layer of a multilayer device. The laser system emits, at pulse repetition rates of greater than 200 Hz, laser output pulses having temporal pulse widths of less than 200 ns and spot areas having diameters of between 50 μm and 300 μm.
Laser removal of a target material, particularly when a UV DPSS laser is used, relies upon directing to the target material a laser output having a power, also referred to as fluence or energy density, that is greater than the removal threshold of the target material. Material removal can be effected by either a photo-chemical process, also called ablation, wherein the forces that hold atoms and molecules together are broken or by a photo-thermal process wherein the material is vaporized. A UV laser emits a laser output that can be focused to have a spot size of between about 5 μm and about 30 μm at the 1/e2 diameter. In certain instances, this spot size is smaller than the desired via diameter, such as when the desired via diameter is between about 50 μm and 300 μm. The diameter of the spot size can be enlarged to have the same diameter as the desired diameter of the via, but such enlargement would reduce the laser output energy density to the extent that it is less than the target material ablation threshold and cannot effect target material removal. Consequently, the 5 μm to 30 μm focused spot size is used and the focused laser output is typically moved in a spiral, concentric circular, or "trepan" pattern to form a via having the desired diameter. Spiraling, concentric circle, and trepanning processing are types of so-called non-punching via formation processes. For via diameters of about 70 μm or smaller, direct punching delivers a higher via formation throughput.
In contrast, the spot size of the output of a pulsed CO2 laser is typically larger than 50 μm and is capable of maintaining an energy density sufficient to effect formation of vias having diameters of 50 μm or larger on conventional target materials. Consequently, a punching process is typically employed when a CO2 laser is used to effect via formation. However, a via having a spot area diameter of less than 50 μm cannot be formed using a CO2 laser.
The high degree of reflectivity of copper at the CO2 wavelength makes very difficult the formation of a through-hole via using a CO2 laser in a copper sheet having a thickness greater than about 5 microns. Thus CO2 lasers can typically be used to form through-hole vias only in copper sheets that have thicknesses of between about 3 microns and about 5 microns or that have been surface treated to enhance the absorption of the CO2 laser energy.
The most common materials used in making multilayer structures for printed circuit board (PCB) and electronic packaging devices in which vias are formed typically include metals (e.g., copper) and dielectric materials (e.g., polymer polyimide, resin, or FR-4). Laser energy at UV wavelengths exhibits good coupling efficiency with metals and dielectric materials, so the UV laser can readily effect via formation on both copper sheets and dielectric materials. Also, UV laser processing of polymer materials is widely considered to be a combined photo-chemical and photo-thermal process, in which the UV laser output partly ablates the polymer material by disassociating its molecular bonds through a photon-excited chemical reaction, thereby producing superior process quality as compared to the photo-thermal process that occurs when the dielectric materials are exposed to longer laser wavelengths. For these reasons, solid-state UV lasers are preferred laser sources for processing these materials.
CO2 laser processing of dielectric and metal materials and UV laser processing of metals are primarily photo-thermal processes, in which the dielectric material or metal material absorbs the laser energy, causing the material to increase in temperature, soften or become molten, and eventually ablate, vaporize, or blow away. Ablation rate and via formation throughput are, for a given type of material, a function of laser energy density or fluence (laser energy (J) divided by spot size (cm2)), power density (laser energy density divided by pulse width (seconds)), pulse width, laser wavelength, and pulse repetition rate.
Thus, laser processing throughput, such as, for example, via formation on PCB or other electronic packaging devices or hole drilling on metals or other materials, is limited by the laser power available and pulse repetition rate, as well as the speed at which the beam positioner can move the laser output in a spiral, concentric circle, or trepan pattern and between via positions. An example of a UV DPSS laser is a Model LWE Q302 (355 nm) sold by Lightwave Electronics, Mountain View, Calif. This laser is used in a Model 5330 laser system or other systems in its series manufactured by Electro-Scientific Industries, Inc., Portland, Oreg., the assignee of the present patent application. The laser is capable of delivering 8 W of UV power at a pulse repetition rate of 30 kHz. The typical via formation throughput of this laser and system is about 600 vias each second on bare resin. An example of a pulsed CO2 laser is a Model Q3000 (9.3 μm) sold by Coherent-DEOS, Bloomfield, Conn. This laser is used in a Model 5385 laser system or other systems in its series manufactured by Electro-Scientific Industries, Inc. The laser is capable of delivering 18 W of laser power at a pulse repetition rate of 60 kHz. The typical via formation throughput of this laser and system is about 1000 vias each second on bare resin and 250–300 vias each second on FR-4.
Increased via formation throughput can be accomplished by increasing the pulse repetition rate at a pulse power that is sufficient to cause ablation as described above. However, for the UV DPSS laser and the pulsed CO2 laser, as pulse repetition rates increase, pulse power decreases in a non-linear fashion, i.e., twice the pulse repetition rate results in less than one-half the pulse power for each pulse. Thus for a given laser, there will be a maximum pulse repetition rate and hence maximum rate of via formation governed by the minimum pulse power needed to cause ablation.
Regarding dicing a semiconductor wafer, there are two common methods of effecting the dicing: mechanical sawing and laser dicing. Mechanical sawing typically entails using a diamond saw to dice wafers having a thickness of greater than about 150 microns to form streets having widths of greater than about 100 microns. Mechanically sawing wafers having a thickness that is less than about 100 microns results in cracking of the wafer.
Laser dicing typically entails dicing the semiconductor wafer using a pulsed IR, green, or UV laser. Laser dicing offers various advantages over mechanically sawing a semiconductor wafer, such as the ability to reduce the width of the street to about 50 microns when using a UV laser, the ability to dice a wafer along a curved trajectory, and the ability to effectively dice silicon wafers thinner than those that can be diced using mechanical sawing. For example, a silicon wafer having a thickness of about 75 microns may be diced with a DPSS UV laser operated at a power of about 8 W and a repetition rate of about 30 kHz at a dicing speed of 120 mm/sec to form a kerf having a width of about 35 microns. However, one disadvantage of laser dicing semiconductor wafers is the formation of debris and slag, both of which could adhere to the wafer and are difficult to remove. Another disadvantage of laser dicing semiconductor wafers is that the workpiece throughput rate is limited by the power capabilities of the laser.
The system and method described herein could also be used to monitor the parameters used to micromachine fusible links on a semiconductor wafer. A system designed to remove fusible links on a semiconductor wafer is described in U.S. Pat. No. 5,574,250 of Sun, et al, also assigned to the assignee of this patent application.
A goal of laser micromachining operations is to provide consistent quality of laser micromachined features over the entire workpiece. Some measures which define feature quality include the location, size, and shape of the feature. Further measures include sidewall angle, bottom texture, volume and texture of debris left in the feature after micromachining, and cracking near the edge of the feature, among others. One problem with laser micromachining operations as discussed herein is that, due to non-uniformities in the workpiece, performing the machining operations with the same laser parameters at two different locations on the workpiece can result in differences in feature qualities. Examples of workpiece differences that influence the results include differences in thickness, differences in workpiece flatness, and differences in surface preparation that makes the workpiece more or less reflective of laser power. These variations are not constant over the entire workpiece and can vary depending upon location down to the individual feature. Furthermore these variations can be repetitive from workpiece to workpiece in a given lot of workpieces due to normal variations in manufacturing tolerances.
Another phenomenon that affects the ability of the laser micromachining system to machine features is aging and/or damage to the optics used to direct the laser beam to the workpiece. As optical components age, they are subject to contamination, most notably from debris from the micromachining operation itself and damage from the high-power laser beams being transmitted through the optics. These and other forms of degradation can cause the laser spot projected onto the workpiece to change in size, shape, intensity or other characteristics, thereby changing the size, shape, depth, or other measures of the feature being micromachined in spite of the exact same parameters being used to control the laser beam.
Prior art systems for laser micromachining use real time controls that alter the parameters of the laser beam as the feature is being machined in an attempt to mitigate the effects of changes in the optics due to aging or damage. In some laser micromachining systems, in particular the systems referenced herein, a photodetector is used to monitor the laser power as the workpiece is being micromachined. The output from the photodetector is used to adjust the laser power in real time in an attempt to compensate for some of the sources of variability in laser power at the workpiece. This is typically accomplished by adjusting a variable attenuator in the optical path to change the laser energy transmitted by the optics to achieve a predetermined amount of energy for each machining operation. If the beam cannot be brought into agreement with a predetermined value, the operation is stopped and the operator is alerted that maintenance is required. The problem with this approach is that although it can help compensate for aging optics or other sources of variation in laser power, the fact that it is automatically compensating for possible deterioration of the laser or optics means that, unless the system is monitored, there is concealment of important information that could be used to trigger maintenance of the system before the system shuts down and valuable production time is lost.
Another issue with trying to maintain consistent quality of laser micromachined feature is that simply recording pre-selected laser parameters such as pulse repetition frequency (PRF) or pulse energy, among others, is not sufficient to characterize the laser parameters used in the micromachining process because the laser beam is typically not directed at the workpiece for the total nominal duration of the micromachining process. For instance, with the laser micromachining systems referenced herein, the laser beam is directed for a portion of the time it is pulsed onto a power meter which measures the power output of the laser beam. The system can then adjust a controllable attenuator in the optical path to cause the laser beam power to be raised or lowered to a pre-selected value. Typically this is used to compensate for reduce transmission by the optical components as they age. If the nominal laser energy value cannot be reached by adjusting the attenuator, the system generates an error signal. The problem is that unless the system is able to record the attenuator setting, the final laser power, and the number of pulses actually delivered to the workpiece, among other parameters, over the specific period of time the feature is being micromachined as opposed to being calibrated, there will exist no accurate record of the actual laser power directed at the workpiece during the micromachining of a particular feature.
Other sources of systematic, repeatable variations in laser micromachined features exist. For example, directing the laser beam to the appropriate locations on the workpiece to efficiently and effectively create multiple complex features can involve coordinating the movement of one or more subsystems, including motion control subsystems that move the workpiece and optical subsystems that move the laser beam. The combined result of these complex coordinated motions that describes the relationship between the workpiece and the laser beam is called the toolpath. The complexity of the toolpath is such that it is subject to repeatable transient behavior that affect the efficiency with which the laser beam interacts with the workpiece. Examples of the types of transient behavior that can affect the laser micromachining process include but are not limited to laser angle with respect to the workpiece and settling time. Another example of transient behavior is the change in laser pulse energy as a function of the pulsing duty cycle of the laser. Due to the toolpath layout and the dynamics beam motion, the time period between processing consecutive features can vary significantly. These delays affect the internal state of the laser, due to variations in stored energy in the lasing medium and thermal transients of optical cavity components. As a result of these laser transients, certain workpiece features may be processed with increased or decreased pulse energy, even if identical processing parameters (pulse repetition frequency, number of pulses, etc.) are applied to the feature. The result of these transient behaviors is systematic variations in feature quality despite identical laser parameter settings.
What is needed in laser micromachining features in a workpiece is, therefore, a method and system for monitoring, identifying, and optionally controlling the actual parameters used to micromachine a particular feature and storing parameter information to enable the system to retrieve the parameter information either in real time, as the feature is being machined or later, after the workpiece is complete.

Energy monitoring or control of individual vias formed during laser micromachining


A method may include authenticating a device to a first server, where the device includes an agent; receiving a request, in the first server from a second server, to verify the authenticity of the device, where the device is not authenticated to the second server; sending a browser plug-in to the device to communicate with the agent for verifying the authenticity of the device; receiving, in the first server, a message from the agent verifying the authenticity of the device; and sending a message from the first server to the second server to authenticate the device to the second server.

More and more organizations are implementing networks in which users authenticate to a server on the network before acquiring access to network services. Once users have access to network services, users may use that access to use network-based applications such as intranets, web-based email, web-based word processors, database services, document management services, content management services, etc. These network-based applications may restrict access to authorized users, and, in this case, will verify the identity of authorized users.


A multi-sided play yard having a collapsible top assembly and a collapsible bottom assembly, each assembly connected to at least three spaced vertical posts. The bottom assembly includes a collapsible assembly with collapsible legs. The collapsible legs each include leg portions pivotally connected to a respective vertical post and to a multiple pivot joint member. Stabilizer feet are pivotally connected to each collapsible leg by a multiple pivot joint member. The vertical posts, leg members, and stabilizer feet serve to support and stabilize the play yard when it is in an erected position.

Play yards are well known. Generally, they include a rectangular shape comprising four corner legs with structure for collapsing the top and bottom assemblies whereby the play yard can be folded in a compact position for storage and portability. While such play yards are satisfactory, it is desired to have a portable, collapsible play yard which is somewhat less cumbersome to collapse by reason of reducing the number of play yard sides. It is further desired to eliminate a play yard side and associated corner leg structure to reduce costs but at the same time the play yard must be relatively easy to erect, and, when erected to a use position, the play yard must be stable and support loads normally attendant with such devices. It is still further desired to provide such a play yard with a minimum of components and with a significantly simplified frame assembly which can be more readily collapsed and erected.


A control server is connected to a plurality of physical nodes that keep control information defining an operation to be taken in accordance with input/output packet characteristics and process the input/output packets according to the control information. The control server includes a first storage unit that stores configuration information about a virtual network configured to include virtual nodes that are virtualized versions of the physical nodes, and a second storage unit that stores virtual network identifying information identifying the virtual network from characteristics of an input packet, and the control server identifies a physical node that configures a virtual network that handles a packet having a characteristic in common with the packet received by the physical node based on a request from the physical node and updates control information for each physical node.

Patent Document 1 discloses a virtual network constructing device that realizes end-to-end security for each service, security between services at a client, and scalability for a large-scale system. According to this document, when a client selects an available service in launcher software transmitted from a path control server after the client's authentication request has been accepted, a corresponding path constructing request is transmitted to the path control server. The path control server issues the client an instruction for connecting to a base router, and also issues the base router an instruction for connecting to the client. The document recites that an in-base VLAN can be dynamically constructed between the client and the base router as a result.
Patent Document 2 discloses a system for managing customers in a hierarchical manner. Further, Patent Document 3 discloses a peer-to-peer network capable of providing a new network topology.
Non-Patent Document 1 proposes a technology called OpenFlow. OpenFlow treats communication as an end-to-end flow, and performs path control, failure recovery, load balancing, and optimization for each flow. An OpenFlow switch that functions as a forwarding node operates according to a flow table appended or updated by an OpenFlow controller according to OpenFlow protocol. In the flow table, pairs of a packet matching rule that specify a packet and an action such as outputting the packet to a specific port, discarding it or rewriting a header are registered as flow entries. When there is a corresponding entry, the OpenFlow switch processes a received packet according to an action written in the entry, and notifies the OpenFlow protocol of the reception of the packet when there is no corresponding entry.    [Patent Document 1] Japanese Patent Kokai Publication No. JP-P2009-135805A    [Patent Document 2] Japanese Patent Kohyo Publication No. JP-P2007-525728A    [Patent Document 3] Japanese Patent Kokai Publication No. JP-P2008-306725A    [Non-Patent Document 1] McKeown, Nick et al., "OpenFlow: Enabling Innovation in Campus Networks," [online], [searched on Jul. 17, 2009]

Information system, control server, virtual network management method, and program


A circuit for controlling the operating power of a fluorescent lamp by detecting the phase of the lamp resonant circuit current and regulating the phase of the current, thereby regulating the lamp power. In the preferred embodiment of the circuit, the phase of the resonant circuit current is detected using a sense resistor disposed between the low side power transistor of a half-bridge driver and ground, or between the lower voltage lamp filament and ground. The zero-crossings of the resonant circuit current is detected by comparing the voltage across the sense resistor to zero voltage. Using these zero crossings, a phase pulse is generated representing the lamp resonant circuit current as a function of time. This phase pulse is compared to a reference pulse to generate an error signal indicative of the phase difference between the phase pulse and the reference pulse. The frequency of the oscillating half-bridge driver is controlled in accordance with the error signal, such that the lamp power, and hence the brightness, is increased or decreased as necessary to keep the phase of the lamp resonant circuit locked to the phase of the reference pulse.

1. Field of the Invention
The present invention relates to a circuit for controlling an electronic ballast and, more specifically, to a phase detection circuit for controlling an electronic ballast.
2. Description of the Related Art
Controlling the brightness (.PHI.) given off by a fluorescent lamp being powered by an electronic ballast requires a circuit whose type can be classified as either "open-loop" or "closed loop". In an "open-loop" design, the controlling circuit knows nothing about what is occurring at the output. The operating point(s) are predetermined and fixed, regardless of changing conditions on the lamp or the ambient temperature. When a high quantity of ballasts which incorporate open-loop control are produced, trimming is required to account for component tolerances. Because the component tolerances alone can be large, the control circuit itself must have high accuracy which increases the cost for a good design. Furthermore, the circuit is still subject to lifetime effects of the lamp and changing ambient temperature.
In contrast, in a "closed-loop" design, information from the output is fed back to the control circuit allowing the circuit to automatically adjust itself for component tolerances, lamp life effects and temperature. Closed-loop control also allows for the lamp to be dimmed with extreme accuracy, which is especially important when a ceiling is filled with lamps, all of which should have the same brightness, particularly at low light levels, where differences from lamp to lamp are more readily detectable with the human eye. Closed-loop circuits also require less accurate designs, therefore reducing costs.
Referring to FIG. 1, one of the most common solutions to controlling the brightness of a fluorescent lamp using a closed-loop approach is to sense the lamp current with the use of a transformer 2. This allows for the lower cathode 4 of the lamp to be heated with the same current as the upper cathode 6, and allows for the lamp current to be separated from the heating current so it can be measured independently.
The lamp current can then be sensed with either a resistor or a second transformer 8. The secondary output of the transformer 8 is then rectified and low-pass filtered before compensated and summed with a reference voltage (REF). The resulting error (ERROR) then tells the control circuit to either increase or decrease the lamp current (usually by changing the frequency of a squarewave (VIN) driving a series/parallel RCL lamp resonant circuit consisting of inductor 12, capacitor 14 and the lamp) depending on whether the feedback signal (VFB) is higher or lower than the desired reference (REF).
The above-described classic control loop, however, has an inherent error due to the non-linear operation of rectification and has a high component count (2 transformers, rectifying diodes, compensation network, error amplifier, etc.).
Other solutions exist as well, but all require the use of a transformer of some sort to sense the actual lamp current.

Phase detection control circuit for an electronic ballast


One embodiment is a method for providing incremental backups for a source computing machine, the method including: (a) creating a first backup snapshot including a virtual machine (VM) snapshot of an initial copy of a source computing machine volume, wherein said VM snapshot includes a timestamp and a first redo log file; (b) reconfiguring and customizing said first backup snapshot to create a first bootable VM, writing changes associated with said reconfiguring and customizing into said first redo log file, then creating a first bootable snapshot including a VM snapshot of said first bootable VM, wherein said VM snapshot of said first bootable VM includes a timestamp for said first bootable VM and a redo log file; (c) performing an incremental update of said first backup snapshot or a subsequent backup snapshot, then creating a subsequent backup snapshot including a VM snapshot of said incremental update, wherein said VM snapshot of said incremental update includes a timestamp for said incremental update and a redo log file; and (d) reconfiguring and customizing said subsequent backup snapshot to create a subsequent bootable VM, then creating a subsequent bootable snapshot including a VM snapshot of said subsequent bootable VM, wherein said VM snapshot of said subsequent bootable VM includes a timestamp for said subsequent bootable VM and a redo log file.

As data storage systems become ever bigger, providing efficient backup storage becomes increasingly important. Even if one is not concerned with the cost of the needed storage space, the time required to perform all the necessary copy operations becomes increasingly burdensome. For a large system, a full backup procedure can be time-consuming, requiring several hours or even days to complete. For this reason, backup procedures often provide "incremental" backups where only blocks or files which have changed since the last backup are copied. Typically, a full backup procedure is performed at infrequent intervals (for example, at an initial time followed by long intervals such as once per month). Thereafter, incremental backups are created more frequently, for example, once per day. Examples of commercial incremental backup products include TRUE IMAGE™ from ACRONIS®, Inc. and NORTON GHOST™ from Symantec Corporation.
Backups can be used for a variety of purposes. They can be used to recover from user error when, for example, the user inadvertently deletes or overwrites a file. They can be used to recover from data loss due to hardware failure such as a hard disk failure. They can also be used to recover from software failures such as application or operating system crashes. The goal of recovery after a crash is to restore the last available known good operating state for the complete system. This can be done by rebooting the same hardware after restoring the file system from a suitable backup, but the recovery procedure can be very time-consuming if the entire file system must be restored. For this reason, virtual machines (VMs) are sometimes used for backup purposes. When a VM is used for backup purposes, it is typically not used as a running machine unless and until it is needed for restoring a failed machine. Typically, the VM is launched, booted, and tested only to verify functionality and then it is shut down; however, it can be brought back on-line quickly if and when needed to replace the failed source machine for which it is functioning as a backup.
Using a VM as a backup is useful in that, if the source machine goes down, the VM can be quickly powered on in its place. With traditional backup methods, a full system restore can take hours, while the VM can be up and running in a few minutes. But whether using traditional file system backups or VMs as backups, changes made since the last backup procedure are lost. Examples of commercial products that enable VMs to be used for backup include POWERCONVERT™ from PLATESPIN®, Ltd. and VEEAM BACKUP™ from Veeam Software.


Even if rope (13) and spring (15) oscillate, to suppress these oscillations as much as possible.. An elevator system is equipped with a car (1) that is installed such that it can freely move up and down in a hoistway, a sheave (14) that is installed at the top of the hoistway, a rope (13) for pulling the car that is suspended from this sheave (14), a suspension rod (9) to which the end of this rope (13) is attached, a spring (15) for damping vibrations which is installed between this suspension rod (9) and the car (1), a cylinder device (16) which attenuates the vibrations and has a flow volume control valve (22), a rotary encoder (24) for detecting the position of the car (1) in order to calculate the length of the rope, a load sensor (25) for detecting the load of the car (1) and a control panel (23) which calculates the characteristic vibration frequency f of the rope (13) from the length of the rope, the characteristic vibration frequency f.sub.N of the spring from the car (1) load, and the vibration frequency ratio u (u=f/f.sub.N), and is made so as to constrict the flow volume control valve (22) of the above-mentioned cylinder device (16) when u=1.

1. Technical Field
This invention relates to a rope-type elevator system that is made so as to reduce the vibrations that are generated at the time of taking up the rope with a winding mechanism or the like.
2. Description of The Prior Art
A rope-type elevator system used in the past, for example, is the one shown in FIG. 5. In this same figure, (101) is a car compartment that is installed movable up and down in a hoistway, and a pair of car rope sheaves (104, 105) are attached by means of car frame (103) to the upper section of this car compartment (101). In other words, car rope sheaves (104, 105) are provided in support channel (106), suspension rod (107) is provided in this support channel (106), and this suspension rod (107) is attached to car frame (103) through the medium of spring seats (108) and a number of spiral coil springs (109). A number of ropes (110) are strung in car rope sheaves (104, 105), and these ropes (110) are hung on drive sheave (111) of the winding mechanism.
Vibrations are generated when the winding mechanism is driven and rope (110) is pulled by drive sheave (111). However, if these vibrations are transferred to the car compartment (101), it gives passengers an unpleasant feeling. Thus, it is relieved by springs (109).
In this known rope-type elevator system, the vibrations that were created from drive sheave (111) of the wind-up mechanism were propagated to car (101) through the ropes (110). There was the problem that the isolation frequency ratio u (u=f/f.sub.N) of the characteristic vibration frequency f of ropes (110) and the characteristic vibration frequency f.sub.N of the springs (109) became u=1 and resonated, and this resonance imparted an unpleasant sensation to passengers within the car.
The present inventors believe that improvements to reduce this sensation are achievable.


The touch panel comprises two conductive substrates arranged in parallel and secured to each other with a gap existing between the conductive substrates The process for implementing a conductive tracing layout in a touch panel includes steps of forming a first conductive layer on at least one of the conductive substrates; forming a first photo-resist layer on the first conductive layer; removing a specified portion of the first photo-resist layer to form a first specified mask on a specified portion of the first conductive layer; and removing the first conductive layer except the specified portion of the first conductive layer to form a first conductive tracing layout.

A cathode ray tube (CRT) monitor has been gradually replaced by a liquid crystal display (LCD) due to the disadvantages of heavy weight, bulky size, and electromagnetic radiation. So far, an LCD has been extensively applied in various information products and communication products such as a notebook PC, mobile phone, portable PC, personal digital assistant (PDA), and so on. The interface of an information product or a communication product provided for a user to input data, for example, could be a touch panel or touch screen, which is attached on the screen of LCD. Then, the input data is measured by detecting the touch point.
A touch pannel is typically produced by aligning and securely combining an upper substrate and a lower substrate, both of which have good electrical conductivity before being attached onto the LCD panel. The upper substrate and the lower substrate are arranged in parallel and secured to each other with a gap existing therebetween. In other words, the upper substrate does not contact with lower substrate directly, and the gap is kept by providing a set of non-conductive spacer dots glued to and clamped between the upper substrate and the lower substrate. The structure of a touch panel could be one of a "film to film" structure (i.e., the upper substrate and the lower substrate are both conductive films, for example indium-tin oxide (ITO) films), a "film to glass" structure (i.e., the upper substrate and the lower substrate include a conductive film and a conductive glass, for example an ITO film and an ITO glass) and a "glass to glass" structure (i.e., the upper substrate and the lower substrate are both conductive glasses, for example ITO glasses).
Currently, the conductive tracing layout in the touch panel is implemented by printing conductive paste, for example silver paste, on the upper substrate and the lower substrate. Various touch panels have been disclosed in prior art such as Japanese Patent No. JP9026852 entitled "Touch Panel", and Japanese Patent No. JP60222918 entitled "Manufacture of Touch Type Input Device", which are incorporated herein for reference.
Please refer to FIG. 1A and FIG. 1B for more details about the conductive tracing layout on the upper substrate and the lower substrate off the touch panel. In FIG. 1A, an example of the conductive tracing layout required by a conventional touch panel is shown. The conventional touch panel 10 mainly includes three areas: an active region 10a, a transparent region 10b and a tracing layout region 10c. The active region 10a is the one where the touch point by an external force can be sensed. The transparent region 10b is of a loop configuration surrounding the active region 10a, and is light-transmissible. The transparent region, on the other hand, has no touch detection function. With regard to tracing layout region 10c, it is also of a loop configuration surrounding the transparent region 10b for providing therein tracing layout required by the touch panel 10. Furthermore, please refer to FIG. 1A, there are four conductive traces 12 disposed on the touch panel 10 and connected to four conductive buses 14 outside the touch panel 10, respectively, which are isolated from one another.
The whole tracing layout shown in FIG. 1A is implemented by separately forming respective portions on the upper and lower substrates, and then gluing the upper and the lower substrates to combine the portions together. FIGS. 1B and 1C schematically show the portions of conductive tracing layout distributed on the upper substrate 20 and the lower substrate 30 of the conventional touch panel, respectively, in other words, while a part of conductive traces 12 are formed on the upper substrate 20, as shown in FIG. 1B, the other part of the conductive traces 12 are formed on the lower substrate 30. By combining the upper substrate 20 and the lower substrate 30 together in parallel, the two portions of conductive traces 12 are combined as the conductive tracing layout shown in FIG. 1A.
Since the above-mentioned conductive tracing layout on the touch panel is achieved in a printing manner that conductive paste is formed on the upper substrate and the lower substrate, there are likely to be some disadvantages as described as follow: (1) relatively large trace width, e.g. larger than 0.5 mm, is required; (2) relatively large line-to-line space, e.g. wider than 0.7 mm, is required due to possible signal loss during signal transmission; and (3) it is hard to narrow down the margins of touch panel, i.e. the distance between the inner and outer edges of the tracing layout region 10C, due to the consideration of adhesion capability of the conductive paste. Generally, the margin of the touch panel is even up to 5.4 mm. Therefore, how to solve these problems will be very important for improving the property of the touch panel.

Process for implementing conductive tracing layout in touch panel


An improved semiconductor device is disclosed having a predetermined amount of solder, or other electrically conductive binder adsorbed onto the exterior package leads of the semiconductor device. A de-wettable coating comprising preferably nickel, or alternatively chromium, is plated to a superior portion of the package leads, such that, when the heat is applied to the substrate mounting end of the leads, solder desorbes from the de-wettable layer and flows down the lead to the contact pads on the mounting substrate and forms a solder joint. The amount of solder delivered to the contact pad for joint formation is determined by the thickness of the adsorbed solder layer overlying each package lead. Only enough solder is provided on each lead sufficient to form the joint thus avoiding solder bridging between adjacent contact pads.

This invention relates to semiconductor devices and more particularly to semiconductor devices having package leads configured for surface mounting the semiconductor device to a mounting substrate.
A continuing trend in semiconductor technology is toward the fabrication of smaller and more complex semiconductor devices having an ever increasing number of circuit components. As the number of circuit components used in semiconductor devices such as integrated circuit devices increases, there is a corresponding increase in the number of wiring connections necessary to electrically connect the integrated circuit device with a user system. In meeting the requirement for more wiring connections and to reduce the overall size of the package, packaging designers have developed packages having external leads that can be mounted directly to the surface of a mounting substrate such as a printed circuit board (PCB). A package configured for surface mounting can incorporate a large number of external leads in a smaller area than, for example, a through-hole mounted package such as a dual-in-line package (DIP). A large number of package configurations have been developed for surface mounting, such as the quad flat package (QFP), the small outline package (SOP), the plastic leaded chip carrier (PLCC) and the fine pitch quad-flat-package (FQFP) being representative examples.
Surface-mount-technology (SMT) has experienced on-going development in part because of the high density device placement on a PCB obtainable using SMT. The high space efficiency on the PCB translates into increased functional power per PCB and lower system cost for the user. The exterior leads on the SMT device are often much shorter and better protected than the leads used in through-hole mountable device such as the DIP. The compact lead configuration of the SMT device can potentially result in a higher yielding board placement process than for a corresponding plated-through-hole (PTH) joining method. In addition, board placement of an surface mountable device is, in general, a simpler more reliable operation than through-hole placement, however, current surface mounting techniques involve several complex steps. First, a solder mask for the PCB must be defined and generated. Then, a solder paste must be applied to the PCB, which requires an alignment step. The actual application of the solder paste is typically done using a stencil process or a screening process, both of which require precise control and monitoring of the physical properties of the solder paste, such as viscosity, particle size distribution and adhesion characteristics. Problems, such as bridging between adjacent contact sites and clogging of the screen, can easily occur if the shear-rate is not precisely adjusted to the viscosity of the paste. Next, the SMT device must be picked up and positioned onto the PCB, which has two patterns thereon, the PCB interconnect layout and the solder mask pattern. This positioning requires a second alignment step. Finally, the solder undergoes a thermal process to make the surface joint by either a vapor phase reflow or an infrared (IR) exposure. It would be advantageous if the solder masking and screening process could be eliminated.
One innovative SMT method is described in my previous patent, U.S. Pat. No. 4,661,887 wherein a surface mountable integrated circuit having solder bearing leads is disclosed. In this method, a solder paste bearing means is provided wherein the solder paste adheres to the package lead, and in one embodiment, is channeled to the end of the lead forming a solder joint to an electrical contact pad on the substrate. Several embodiments of this invention are disclosed wherein the solder bearing means includes for example, a spiral groove filled with solder paste and extending the length of the lead, and for example, vertical slots filled with solder paste extending down a portion of the length of the lead. While this method is effective in simplifying the SMT process by eliminating the solder paste screening step, the tooling of the leads necessary to form the solder bearing means increases the cost of lead manufacturing and can in some cases reduce the mechanical rigidity of the lead. Another disadvantage with this method is that solder must completely wet the surface of the leads, which results in a requirement to use more solder on each lead than the amount actually necessary to form a solder joint between the lead and a contact land on a PCB. It would therefore be advantageous if a surface mountable semiconductor device could be fabricated that is readily mountable to a substrate mounting surface having exterior leads bearing an exact amount of solder necessary for contact joint formation and that does not require tooling of the leads.

Surface mountable semiconductor device having self loaded solder joints


A differential amplifier with adjustable linearity is disclosed herein. The differential amplifier includes a differential pair amplifier and a linearization circuit. The differential pair amplifier receives a differential input voltage and amplifies the differential input voltage to produce an amplified output voltage. The linearization circuit receives the amplified output voltage and generates a compensation signal in response thereto. The compensation signal, which has a magnitude adjustable in response to a linearity adjustment signal, is applied to the differential pair amplifier. The differential pair amplifier uses the compensation signal to apply compensation to the amplification of the differential input voltage. Thus, the linearity of the differential amplifier is adjustable by modifying the linearity adjustment signal. The differential pair amplifier includes a bipolar differential transistor pair having their emitters coupled together to form a common emitter node. A first adjustable current source coupled to the common emitter node provides a gain adjustment signal for adjusting the gain of the differential pair amplifier. The linearization circuit includes a diode element pair having their cathodes coupled together to form a common cathode node. A second adjustable current source coupled to the common cathode node provides the linearity adjustment signal for adjusting the linearity of the differential pair. In another embodiment, the differential pair amplifier includes a differential common-base amplifier.

Differential amplifiers are used to amplify the difference voltage between two input signals. A common mode input change occurs when the two input signals change together, and a normal mode input change occurs when the difference voltage between the two input signals changes. Ideally, the output voltage of a differential amplifier responds only to normal mode input changes and is independent of common mode input changes. The response of a differential amplifier can be measured by determining the ratio of the response for a normal mode signal to the response for a common mode signal. This quantity is the common-mode rejection ratio (CMRR), with good differential amplifiers having high CMRRs.
The normal mode voltage gain of a differential amplifier is the ratio of the amplified output voltage to the differential input voltage. Ideally, the gain of a differential amplifier does not depend on the magnitude of the differential input voltage. However, gain of a differential amplifier typically has a maximum value when the differential input voltage is small, and then decreased values as the magnitude of the differential input voltage increases. The change in gain causes distortion in the amplified output voltage. The degree to which the gain changes based on the differential input voltage can be specified as the linearity of the differential amplifier. Amplifier linearity, for example, can be defined as the largest differential input voltage within an acceptable gain limit of -1 dB, with good differential amplifiers having high linearity and, hence, low distortion and high dynamic range.
A conventional differential amplifier circuit 10 is shown in FIG. 1. Circuit 10 includes a first transistor 12 and a second transistor 14 arranged as a pair. Transistors 12 and 14 each have a base, a collector, and an emitter. The emitters of transistors 12 and 14 are connected together at a common emitter node 16. The collectors of transistors 12 and 14 are each connected to a first supply voltage +V.sub.CC through first and second load elements 18 and 20, respectively. Load elements 18 and 20 may include, for example, resistors R.sub.L or impedances Z.sub.L. A differential input voltage V.sub.IN is connected across the bases of transistors 12 and 14, with the positive V.sub.IN node connected to the base of transistor 12 and the negative V.sub.IN node connected to the base of transistor 14. Common emitter node 16 is connected to a second supply voltage -V.sub.EE through an adjustable current source 22. The amplified output voltage V.sub.OUT of circuit 10 is taken across the collectors of transistors 12 and 14, with the positive V.sub.OUT node at the collector of transistor 14 and the negative V.sub.OUT node at the collector of transistor 12. Transistors 12 and 14 are, for example, bipolar npn transistors formed within a common integrated circuit.
The voltages around the loop including differential input voltage V.sub.IN and the base-emitter junctions of transistors 12 and 14 yields: EQU V.sub.IN -V.sub.BE1 +V.sub.BE2 =0 (1)
Provided that V.sub.BE1 and V.sub.BE2 are much greater than the thermal voltage V.sub.T (25.3 mV at room temperature of 68.degree. F. or 20.degree. C.), the Ebers-Moll transistor model yields: EQU V.sub.BE1 =V.sub.T In(I.sub.1 /I.sub.S1) (2) EQU V.sub.BE2 =V.sub.T In(I.sub.2 /I.sub.S2) (3)
wherein the thermal voltage V.sub.T =kT/q, k is Boltzmann's constant (1.38.times.10.sup.-23 joules/.degree. K), T is the absolute temperature in degrees Kelvin, q is the electron charge (1.60.times.10.sup.-19 coulombs), and I.sub.S1 and I.sub.S2 are the saturation currents of transistors 12 and 14, respectively. Combining equations (1) through (3) and solving for I.sub.1 /I.sub.2 gives the ratio of the collector currents: EQU I.sub.1 /I.sub.2 =exp(V.sub.IN /V.sub.T) (4)
wherein saturation currents I.sub.S1 and I.sub.S2 of transistors 12 and 14 are assumed to be equal (i.e., transistors 12 and 14 are matched). Now, assuming that the current gain h.sub.FE of transistors 12 and 14 is high so the base currents can be ignored, summing the current into common emitter node 16 yields: EQU I.sub.E =I.sub.1 +I.sub.2 (5)
wherein I.sub.E is the tail current through current source 22. Combining equations (4) and (5), the collector currents can be written as: EQU I.sub.1 =I.sub.E /(1+exp(-V.sub.IN /V.sub.T)) (6) EQU I.sub.2 =I.sub.E /(1+exp(V.sub.IN /V.sub.T)) (7)
Referring to FIG. 2, collector currents I.sub.1 and I.sub.2 are plotted as a function of differential input voltage V.sub.IN. The graph shows that at V.sub.IN =0, tail current I.sub.E is split equally between transistors 12 and 14. At high positive V.sub.IN, tail current I.sub.E passes substantially through transistor 12 (i.e., I.sub.1 =I.sub.E and I.sub.2 .apprxeq.0). At high negative V.sub.IN, tail current I.sub.E passes substantially through transistor 14 (i.e., I.sub.2 .apprxeq.I.sub.E and I.sub.1 .apprxeq.0).
The voltage gain A.sub.V of differential amplifier circuit 10 is defined as: EQU A.sub.V =V.sub.OUT /V.sub.IN (8)
wherein EQU V.sub.OUT =R.sub.L (I.sub.1 -I.sub.2)=R.sub.L .DELTA.I (9)
The small signal gain of differential amplifier circuit 10 is: EQU A.sub.V =g.sub.m R.sub.L (10)
wherein the transconductance, g.sub.m, is: EQU g.sub.m =(.differential.I.sub.c /.differential.V.sub.be)=1/2I.sub.E /V.sub.T (11)
Thus, g.sub.m depends on the adjustment of adjustable current source 22.
Referring to FIG. 3, the small signal gain A.sub.V =g.sub.m R.sub.L is the maximum voltage gain which occurs at small magnitudes of differential input voltage V.sub.IN (e.g., at V.sub.IN =0, A.sub.V =g.sub.m R.sub.L). However, as shown, voltage gain A.sub.V decreases as the magnitude of V.sub.IN increases. The amplifier linearity can be defined as the largest magnitude of V.sub.IN wherein voltage gain A.sub.V is within acceptable gain limits. For example, if the acceptable gain limit is -1 dB, amplifier linearity is within the range of V.sub.IN to V.sub.IN+. However, the linearity of the circuit of FIG. 1 is relatively low, and it would be desirable to provide a differential amplifier circuit having expanded linearity.

Differential amplifier with adjustable linearity


This invention relates to methods of manufacturing fluid-filled MEMS displays, where the fluid is sealed in the display assembly and substantially surrounds the moving components of the display to reduce the effects of stiction and to improve the optical and electromechanical performance of the display.

Displays built from mechanical light modulators are an attractive alternative to displays based on liquid crystal technology. Mechanical light modulators are fast enough to display video content with good viewing angles and with a wide range of color and grey scale. Mechanical light modulators have been successful in projection display applications. Backlit displays using mechanical light modulators have not yet demonstrated sufficiently attractive combinations of brightness and low power. There is a need in the art for fast, bright, low-powered mechanically actuated displays.
Unlike in liquid crystal displays, MEMS-based displays include hundreds, thousands, or in some cases, millions of moving elements. In some devices, every movement of an element provides an opportunity for stiction to disable one or more of the elements. The unreliable operation of these elements can lead to inferior picture quality and potentially even inoperability of the display as a whole.

Methods for manufacturing fluid-filled MEMS displays


Information collections defining a common subject such as a codified or uncodified body of law are stored on a computer readable medium in association with temporal information indicating the state or status with respect to time of parts of the information collection, including different versions of the same part. Parts of an information collection that are different versions of each other have different temporal information associated therewith and can be accessed based on the temporal information. Thus, the temporal information may be used to control access to and display of parts of the subject in a computer system based on time as search or request parameter. In a preferred embodiment, the subject is a statutory body of law such as the United States Code. Sections of the Code are stored in association with temporal information such as date of enactment, effective date and termination date. A researcher can access a version of any part of the Code in effect at any particular time.

The invention generally relates to collections of information and to systems that include, and/or access, retrieve, display and/or otherwise perform operations involving, such information collections. In particular, the invention relates to information collections that include information that may change with time, and which maintain a status, state or other relationship of information in the collection with respect to time. For example, the information collections may store historical as well as current information in association with related temporal information. In preferred embodiments, the information collections comprise a body of law and store historical and current versions of the body of law and parts thereof.
The term "information collection" is used herein in a broad sense and, unless the context indicates otherwise, encompasses databases, information bases, knowledge bases, bodies of information, etc., stored on a computer readable medium (electronic, magnetic, optical, etc.) or otherwise accessible by a computer device. Similarly "information" is used herein in a broad sense and, unless the context indicates otherwise, encompasses data. Unless the context indicates otherwise, the terms "information" and "data" may be used herein interchangeably, and the terms "information collection," information base," "knowledge base" and "database" may be used herein interchangeably. Similarly, the term "body of law" is used herein in a broad sense and encompasses bodies of law, codified and uncodified, such as codes, sets and codifications of laws, regulations, administrative rules, etc.
Some information collections include information that changes with time, and, in a sense, are dynamic. For example, a dictionary is a collection of words and their meanings; both the composition of the collection and the meanings of words in the collection may change over time. Frequently, words have multiple meanings in dictionaries and include historical information. Other examples are version control and configuration management systems that include historical and current versions of documents and software.
Still another example of an information collection that may change over time is a body of law, for example, promulgated by a governmental or quasi-governmental or other organization.
Such information collections may include historical information in the form of commentary, historical data, annotations, legislative history, references to other laws or judicial decisions, case notes, etc., as well as the current version of the body of law.
In the above examples, the subjects of the information collections can be rather large. To facilitate working (e.g., storing, accessing, retrieving, displaying, etc.) with an expansive subject, it is often necessary to provide some kind of organizational structure for the information. For some applications of a dynamic subject that may change over time, not only would an organizational structure be beneficial, but it would be useful to be able to track status or obtain the current state of parts of the subject, or to obtain historical information such as earlier versions of parts of the subject.
Bodies of law and/or parts thereof typically take effect on some date after enactment, and remain in effect until a specified expiration date, or indefinitely (or in perpetuity), unless altered or terminated by an intervening enactment. However, some bodies of law and/or parts thereof have retroactive effect from the date of enactment. In addition, at the time of enactment, a body of law or part thereof may have a duration that is not certain. For example, a body of law or part thereof becomes and/or ceases to be effective at some time triggered by an event that is not certain at the time that the body of law or part thereof was enacted. Possibly, such a body of law or part thereof might never actually go into effect if its initial effective conditions are not met. Likewise, a termination condition could fail to occur. It is also possible that a body of law or part thereof might be enacted with an effective date that, because of a subsequent enactment, may never take effect.
Therefore, ascertaining the status or state of any body of law or part thereof at any given time or interval of time can be difficult. Also, many bodies of law typically include one or more parts and/or sub-parts that may be modified independently of each other, which can compound any uncertainty or lack of clarity in the status or state of the parts and sub-parts.

Dynamic legal database providing historical and current versions of bodies of law


A waterproof, vapor-permeable and gas-permeable sheet material and a method of making are provided. The sheet material includes a waterproof microporous layer and a thermoplastic layer attached to the microporous layer. The thermoplastic layer is vapor-permeable and air-permeable. The microporous layer is at least partially integrated with the thermoplastic layer to form a zone that prevents passage of water droplets, while permitting passage of water vapor and air, when a chemical is present on the sheet material that would otherwise cause the microporous layer to permit passage of water droplets. The Zone can be considered to be resistant to chemical interference with at least the waterproof property of the microporous layer and inhibits detachment of the layers.

Fluoropolymers and thermoplastic elastomers are known and are used in many different applications, including outdoor sheet materials or films. A fluoropolymer layer or a thermoplastic elastomer layer may be utilized to provide some desired properties, such as breathability or resistance to water penetration. Thus, it is known to provide a breathable and water resistant sheet material. Such a sheet material is very useful in an outdoor environment. For example, such sheet material can be used to make articles of clothing, outdoor gear, protective articles and the like. However, the presence of some chemicals, such as from insect repellant, may cause degradation of at least some of the properties of the sheet material such as the level of water penetration resistance. Specifically, propensity that the sheet material will permit penetration/passage of water will be increased due to the chemical presence on the sheet material. Such increased propensity to permit penetration/passage of water may be referred to as wetting out.

Air permeable waterproof bicomponent film


In a system controller (102) a quantity of control channels is determined; a portion (344) of a code word (338) is set to identify the quantity of control channels; the code word (358) is transmitted in a predetermined portion (332) of each of a plurality of radio signals. In a multichannel radio (106) a receiver (610) is set to a first channel which includes one of the plurality of radio signals; the portion (344) of the code word (338) is decoded; one of the set of control channels is identified as a new home control channel, the home control channel is revised to the new home control channel, and the receiver (610) is set to the home control channel as revised. The one of the set of control channels is identified based on the quantity of control channels and a predetermined number in the multichannel radio (106).

In some multichannel radio systems having a plurality of outbound radio channels used by a plurality of multichannel radios, it has been found useful to define for each multichannel radio one of the plurality of outbound radio channels as a home control channel. Information and commands are sent to a multichannel radio, using the home control channel to notify the multichannel radio that information or commands are to be sent, and to indicate to the multichannel radio within which channel of the plurality of channels the information or command is to be sent. The set of home control channels forms a set of control channels, which may include all of the plurality of outbound channels used in the radio communication system, or may be a subset of the plurality of channels. The channels which are not control channels can be used for other purposes, such as temporarily assigning a multichannel radio to for receipt of a message which is long, or a message which has a bandwidth incompatible with the control channels. The number of control channels used in this type of system to achieve optimum efficiency typically varies depending on the statistics of the types of messages sent and the number of multichannel radios used. Therefore, it is desirable to be able to assign a home channel and change a home channel assignment of the multichannel radios in such a system.
A known technique of reassigning a home channel is to send an individual command to each multichannel radio, or each group of multichannel radios, commanding the multichannel radios to respond to a channel reassignment. For large systems, such as nationwide paging systems having zones which use a plurality of outbound control channels and have many thousands of multichannel pagers, individual and group addressing is very inefficient, however, because a command must be generated for each multichannel radio or group of multichannel radios requiring reassignment.
Thus, what is needed is a efficient means for efficiently changing a home control channel assignment for a multichannel radio in a radio communication system in which the number of control channels can vary.

Method and apparatus for receiving a radio signal within a home control channel in a multichannel radio communication system


A system is provided to clearly determine a problem in the discharge of a capacitor provided for an inverter of an electric vehicle and its cause. If a capacitor voltage drops below a predetermined value at the end of a first predetermined time period after a main contactor is turned off, it is determined that the main contactor and a discharge circuit are normal. If the capacitor voltage drops below the predetermined value for the first time after a second predetermined time period, it is determined that the discharge circuit has failed and discharge is performed by a discharge resistor. If the capacitor voltage is still above the predetermined value after the second predetermined time period, it is determined that the main contactor has failed and is fixed in a turned-on state.

1. Field of the Invention
The present invention relates to a control system for an electric vehicle provided with an inverter for converting DC electric power of a main battery into AC electric power to drive a traveling motor.
2. Description of the Prior Art
A large-capacity electrolytic capacitor is provided between terminals of the input side of an inverter of an electric vehicle in order to smooth the fluctuation of voltage and stabilize the operation of the inverter. To run the electric vehicle, a traveling motor is driven through the inverter by closing a contactor by operating a main switch and charging the capacitor. To stop the traveling of the electric vehicle, the electric charge stored in the capacitor is discharged through a discharge circuit after opening the contactor by operating the main switch (see Japanese Patent Application No. 6-161535).
However, because failure of the discharge circuit or the contactor cannot be determined in the prior art, a discharge problem with the capacitor might occur if the discharge circuit or the contactor fails.


A method of generating a check matrix for a LDPC code includes determining a code length and a coding rate, and a basic matrix; selecting a maximum value of the weight of the column; searching an ensemble of the weights of the row and the column weights; deleting the rows sequentially from a bottom of the basic matrix; searching an ensemble of the weights of the row and the column using the set of the weights of the row as a fixed parameter, to determine an optimum set of the weights of the column; searching an optimal ensemble of the weights of the row and the column using the set of the weights of the row and the column as a fixed parameter; and dividing at random the weights of the row and the column of the basic matrix after deleting the rows in a predetermined procedure based on a final ensemble.

A conventional method of generating a check matrix for an LDPC code will be explained below. FIG. 13 illustrates an LDPC encoding/decoding system. Reference numeral 101 denotes an encoder, 102 denotes a modulator, 103 denotes a channel, 104 denotes a demodulator, and 105 denotes a decoder. Prior to explanation of a conventional method of generating check matrixes for LDPC codes, encoding and decoding using LDPC codes are explained first.
At the sending side, the encoder 101 generates a check matrix H using a certain method. Then, a generator matrix G is derived from the following condition.
G:k×n matrix (where k is information-length and n is code-word length)
GHT=0 (where T is transposition)
The encoder 101 then receives a message (m1 m2 . . . mk) of an information-length k, and generates a code-word C using the generator matrix G as follows:
                    C        =                              (                                          m                1                                                                                m                2                                                                                …                                                                                m                k                                      )                              G                                        =                              (                                          c                1                                                                                c                2                                                                                …                                                                                c                n                                      )                                                        (                                                where                                                                                H                                                                    (                                                                              c                            1                                                                                c                            2                                                                                …                                                                                c                            n                                                                          )                                                              T                                                  =                0                            )                        .
The modulator 102 subjects the generated code-word C to digital modulation such as BPSK, QPSK or multi-valued QAM and transmits the resultant modulated signal.
At the receiving side, the demodulator 104 receives the modulated signal via the channel 103, and subjects it to a digital demodulation such as BPSK, QPSK or multi-valued QAM. The decoder 105 then subjects the LDPC-coded, demodulated result to an iterative decoding by "Sum-Product Algorithm" and provides an estimated result (corresponding to the original m1 m2 . . . mk).
Conventionally, check matrixes for the LDPC codes are generated as explained below. As the check matrix the LDPC code, for example, following matrix is proposed by Gallager (see Non-patent Literature 1, FIG. 14).
This matrix is a binary matrix of "1" and "0". Parts of "1" are hatched and parts of "0" are white. There are four "1"s in one row (hereinafter, "row weight"), and there are three "1"s in one column (hereinafter, "column weight"). All columns and rows have respective uniform weights. Thus, it is generally called "Regular-LDPC Code". In the Gallager's codes, as shown in FIG. 14, the matrix is divided into three blocks, for example, and the second and third blocks are subjected to random permutation.
Because the random permutation has no certain rule, it is required to execute a time-consuming search by computer to find codes with a better characteristic.
Euclidean geometry codes are such LDPC codes that exhibit a relatively stable and nice characteristic and can definitely generate a matrix without the use of the computer search. Y. Kou et al. have proposed a method using such Euclidean geometry codes. This method explains "Regular-LDPC Codes" consisting of regular ensembles (see Non-patent Literature 2).
A method of generating a check matrix for LDPC codes is herein proposed using Euclidean geometry codes EG(2, 26) or a kind of finite geometric codes. This method achieves a characteristic that is located closely but 1.45 decibels away from the Shannon limit at an error rate of 10-4. FIG. 15 illustrates a configuration of Euclidean geometry codes EG(2, 22), which has a structure of "Regular-LDPC Codes" with row and column weights of 4, 4.
Euclidean geometry codes EG(m, 2s) have a characteristic defined as follows                Code length: n=22s−1        Redundant bit length: n−k=3s−1        Information length: k=22s−3s         Minimum distance: dmin=2s′+1        Density: r=2s′/(22s−1).
As can be seen from FIG. 15, Euclidean geometry codes have a structure with a cyclically sifted location of "1" in each row from an adjacent row. This structure can characteristically configure codes easily and definitely.
The check matrix generating method by Y. Kou et al. further includes changing row and column weights based on the Euclidean geometry codes to extend rows and columns, if required. For example, when a column weight in EG(2, 22) is separated into halves, in the paper by Y. Kou et al., every other one of four weights located in one column is separated into two groups. FIG. 16 illustrates an exemplary regular separation of the column weight from 4 into 2.
On the other hand, Ludy et al. have reported that "Irregular-LDPC Codes" have a better characteristic than that of "Regular-LDPC Codes" (see Non-patent Literature 3). The "Irregular-LDPC Codes" represent such LDPC codes that have non-uniformity in either or both of row and column weights.
Richardson et al. have analyzed it theoretically (see Non-patent Literature 4) as well as Chung et al. (see Non-patent Literature 5).
In particular, Chung et al. analyze a "Sum-Product Algorithm" for LDPC codes, on the assumption that a log-likelihood-ratio (LLR) between an input and an output at an iterative decoder can be approximated in a Gaussian distribution, to derive a nice ensemble of row and column weights.
Non-patent Literature 1
R. G. Gallager, "Low-Density Parity-Check Codes", Cambridge, MA: MIT Press, 1963.
Non-patent Literature 2
Y. Kou, S. Lin, and M. P. C. Fossorier, "Low Density Parity Check Codes Based on Finite Geometries: A Rediscovery," ISIT 2000, pp. 200, Sorrento, Italy, Jun. 25 to 30, 2000.
Non-patent Literature 3
M. G. Luby, M. Mitzenmacher, M. A. Shokrollahi, and D. A. Spielman, "Improved Low-Density Parity-Check Codes Using Irregular Graphs and Belief Propagation," Proceedings of 1998 IEEE International Symposium on Information Theory, pp. 171, Cambridge, Mass., Aug. 16 to 21, 1998.
Non-patent Literature 4
T. J. Richardson and R. Urbanke, "The capacity of low-density parity-check codes under message-passing decoding," IEEE Trans. Inform. Theory, vol. 47, No. 2, pp. 599 to 618, February 2001.
Non-patent Literature 5
S.-Y. Chung, T. J. Richardson, and R. Urbanke, "Analysis of Sum-Product Decoding of Low-Density Parity-Check Codes Using a Gaussian Approximation," IEEE Trans. Inform. Theory, vol. 47, No. 2, pp. 657 to 670, February 2001:
In the conventional method of generating check matrixes for LDPC codes by Chung et al., however, the number of "1" points in a row (corresponding to a degree distribution of variable nodes later described) and the number of "1" points in a column (corresponding to a degree distribution of check nodes later described) are both employed. as variables to derive the degree distribution of variable nodes and the degree distribution of check nodes that can maximize the following equation (1) (rate: coding rate). In a word, a linear programming is employed to search an ensemble that minimizes a signal-to-noise ratio (SNR).
                    rate        =                  1          -                                                    ∫                0                1                                                          ρ                                                  (                  x                  )                                                                                ∫                0                1                                                          λ                                                  (                  x                  )                                                                                (        1        )
Therefore, a problem arises because a check matrix derived from the maximum of the "rate" has a flux and unstable characteristic. In addition, the conventional method of generating check matrixes for LDPC codes iteratively executes the derivation of the degree distribution of variable nodes and the derivation of the degree distribution of check nodes over certain times. Therefore, a problem arises because it takes time to some extent for searching.
The present invention has been achieved in consideration of the above problems, and accordingly has an object to provide a method and an apparatus for generating a check matrix of a satisfactory performance for the an LDPC code capable of easily searching a definite and characteristic stabilized check matrix for the LDPC code corresponding to an optional ensemble.

Check matrix generation method and check matrix generation device


A system for determining the absolute position of a multi-turn shaft is disclosed. The shaft is mounted in an elliptically shaped wave generator. The wave generator is coupled to a flex spline which is deformed to match the wave generator. The exterior surface of the flex spline has a number of gear teeth. The flex spline is installed within a cylindrical, circular spline. The circular spline has an interior diameter which is slightly larger than the largest diameter of the flex spline. The interior surface of the circular spline has a number of teeth which interlock with the teeth of the flex spline. In such a manner, the rotation of the shaft will cause an angular displacement of the circular spline. A position sensor is located on the circular spline and serves to track the position of the circular spline which is proportional to the absolute position of the shaft.

This invention relates to a sensor to determine the rotational angle of a multi-turn shaft. More specifically, this invention relates to an angular sensor that determines the absolute position of a multi-turn shaft.
In the automotive and other fields, rotational control devices such as steering wheels may turn several times in order to enable a full range of operation. In the case of a steering wheel for example, the wheel is turned three times for the full range of turning the front wheels of a car. The angular position of the steering wheel must be measured and additionally the number of turns completed must also be determined in order to determine the real position of the front wheels.
In order to determine angular position, a potentiometer is attached to a circular resistor located around the shaft and a wiper contact is attached to one point on the circumference of the shaft. The resistance changes with the movement of the wiper contact and thus the voltage measured by the potentiometer changes as the shaft is rotated, providing a determination of the angle of the shaft. Additional circuitry is required to record the precise position of the shaft by staring the number of rotations in order to obtain the true position of the front wheels. Such circuitry unnecessarily complicates the sensor system.
Some present systems use mechanical solutions to magnify the effect of the angle of the shaft rotation. Such mechanical configurations include a relatively complex helical or spur gear system. Thus, the single rotation cycle of the shaft will translate in smaller increments of movements via the helical or spur gear. Unfortunately, the use of helical or spur gears adds to the complexity and expense of the steering assembly. Additionally, with increasing numbers of gears, mechanical backlash becomes problematic.
Thus, there exists a need for a simple absolute position sensor for a multi-turn shaft assembly. There is also a further need for an absolute position sensor that may determine the angular position of a shaft assembly without the use of processing circuitry to determine the number of turns of a shaft. Also, there exists a need for a position sensor that may be used in conjunction with an in-line, concentric assembly of a multi-turn shaft. Finally, there exists a need for a position sensor that may be used in conjunction with a gearing assembly that eliminates gear backlash.
The present invention may be embodied in an angular position sensor system for determining the absolute position of a rotating member. The sensor system has a drive assembly coupled to the rotating member. The drive assembly includes a wave generator having an elliptical shape. A flex spline is coupled to the wave generator. The flex spline has an exterior surface with teeth. A cylindrical spline has a diameter larger than the largest diameter of the flex spline and an interior surface with teeth which interlock with the teeth of the flex spline. The cylindrical spline rotates at a proportional angle of rotation when the rotating member is rotated a full revolution. A position sensor is operatively coupled to the drive assembly and outputs the angular absolute position of the rotating member.
The present invention may also be embodied in an angular position sensor system for determining the absolute position of a rotating shaft. The sensor system has a drive assembly coupled to the shaft. The drive assembly has a wave generator having an elliptical shape coupled to the shaft. A flex spline is coupled to the wave generator. The flex spline has an exterior surface with teeth. A cylindrical spline has a diameter larger than the largest diameter of the flex spline and an interior surface with teeth which interlock with the teeth of the flex spline. The cylindrical spline rotates at a proportional angle of rotation when the shaft is rotated a full revolution. A position sensor is operatively coupled to the cylindrical spline and outputs the angular absolute position of the shaft.
It is to be understood that both the foregoing general description and the following detailed description are not limiting but are intended to provide further explanation of the invention claimed. The accompanying drawings, which are incorporated in and constitute part of this specification, are included to illustrate and provide a further understanding of the method and system of the invention. Together with the description, the drawings serve to explain the principles of the invention.
FIG. 1 is a perspective view of a rotational position sensor in conjunction with a harmonic drive assembly according to one embodiment of the present invention.
FIG. 2 is an exploded view of the rotational position sensor and harmonic drive assembly of FIG. 1.
FIG. 3 is a side cutaway view of the rotational position sensor and harmonic drive assembly of FIG. 1.
FIGS. 4A-C are side cutaway views of the harmonic drive shown in FIG. 1 in various angles of rotation of the shaft.
FIG. 5 is a side view of an alternate embodiment of a position sensor for a multi-turn shaft.
FIG. 6 is a side view of an alternate embodiment of a harmonic drive assembly which incorporates a position sensor according to the present invention.

Absolute angle sensor for multi-turn shaft


A method of manufacturing a semiconductor package, including at least a step A that forms a first transforming portion by irradiating a laser beam on at least a portion of a first substrate; a step B that joins together the first substrate and a second substrate in which a functional element is disposed; a step C that removes the first transforming portion that is disposed on the first substrate by etching; and a step D that forms a conductive portion in the first substrate by filling a conductive material in a portion where the first transforming portion has been removed.

1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor package that has through electrodes.
2. Description of Related Art
With the increasing sophistication of electrical equipment such as mobile telephones in recent years, there is a demand for further increases in the speed and performance of electronic devices and the like that are used in the equipment. In order to meet these demands, technical development is required not only to increase the speed of the device itself through miniaturization and the like, but also to increase the speed and density of the package of the device.
For technologies that achieve high-density mounting, three-dimensional stacking technology that laminates and mounts chips by providing fine through-electrodes in the chips and System in Package (SIP) technology that uses a substrate having through-electrodes formed therein have been proposed. Research and development of through-electrode formation technology and through-electrode substrate formation technology for realizing these mounting technologies have been conducted (for example, refer to related art Japanese Unexamined Patent Application, First Publication No. 2002-158191).
Also, as a microvia-formation technology, research has been conducted for forming microvias by transforming the substrate interior by a laser or the like and removing the transformed portion by etching (for example, refer to related art Japanese Unexamined Patent Application, First Publication No. 2006-303360).
Thinning of the substrate by polishing the rear surface of the substrate in order to reduce the size of the package has also been conducted. Also, in order to solve problems related to handling or the like during the thinning process, a method of joining a holding substrate to a substrate and polishing the silicon on the rear surface of the substrate has been proposed (for example, refer to related art Japanese Unexamined Patent Application, First Publication No. 2006-228947).
The abovementioned holding substrate is used, for example, when thinning the substrate, but is removed upon the completion of thinning the substrate. Also, with regard to a substrate in which through-electrodes are formed, a process for joining the manufactured substrate together with a substrate in which a functional element is arranged is required. Thus, the manufacturing time increases. Since the method disclosed in related art Japanese Unexamined Patent Application, First Publication No. 2006-228947 involves removing the holding substrate that was joined for thinning a substrate and laminating again a substrate for forming through electrodes, the manufacturing time increases.
The present invention was made in view of the related circumstances, and has an object of providing a method of manufacturing a semiconductor package that eliminates the need for removing the holding substrate after the completion of processing of the semiconductor substrate and is thereby capable of reducing the manufacturing time.

Method of manufacturing semiconductor package


A method includes positioning a casing into a wellbore. Cement is pumped through the casing to cement the casing in the wellbore. A casing hanger is positioned within a casing head spool that is part of a surface wellhead assembly at an uphole end of the wellbore. The casing hanger is attached to an uphole end of the casing. A production tubing string including a plurality of production tubing segments is positioned within the casing within the wellbore. An uphole end of the production tubing string is attached to a lower end of a rotating inner mandrel of a production tubing hanger. The production tubing hanger is configured be positioned within a tubing head spool positioned above the casing head spool within the surface wellhead assembly. The rotating inner mandrel is configured to rotate within a non-rotating housing of the production tubing hanger. The production tubing string is rotated by rotating a landing joint including a production tubing segment attached to an upper end of the rotating inner mandrel. While rotating the production tubing string, cement is pumped through the production tubing string to at least partially cement the production tubing string within the wellbore.

Wells for hydrocarbon production or other applications are completed and made ready for production by cementing a casing within the wellbore and inserting a production tubing string within the casing. Hydrocarbons or other fluids can be produced from a subterranean formation up through the production tubing string.
In a conventional completion, production packers are positioned on the production tubing string to isolate and seal the annulus around the exterior of the production tubing. In a so-called "cemented completion," in contrast, isolation of the annulus around the exterior of the production tubing is accomplished by cementing the production tubing within the wellbore. In some cemented completions, no production packers are used, as the cement around the production tubing string acts to center the production tubing string and seal the annulus such that no packers are necessary.

Rotating tubing hanger for cemented completion


A two step method to increase the thickness of human hair in which in Step I, a high pH priming lotion is applied to pre-treat the hair to increase its pH, create an anionic charge and therefore loosen and lift the cuticle layers of the hair. In Step II, an acidic thickening composition is applied on top of the Step I composition to deliver polymers and conditioning ingredients to the hair's polypeptide molecule sites. The Step II components have cationic sites that chemically bond to anionic groups in the hair, making them substantive to the hair wherein they deposit under and around the crevices of the cuticles. The low pH of Step II tightly closes the cuticles, sealing the substantive ingredients to the surface of the hair, providing the hair with increased diameter and long lasting thickness.

Hair care products specifically formulated to provide body and thickness to fine hair have long been commercially available. Shampoos that are common to the marketplace are typically formulated to have pH ranges that are acidic to neutral, for example, about 5.5 to 7.0. However, as described in Rousso et al U.S. Pat. Nos. 6,010,990 and 6,348,439 ("High Alkaline Hair Compositions for Increased Fullness and Body"), many low pH to neutral pH hair shampoos do not provide lasting fullness and body to fine and very fine hair. Rousso et al contended that low pH works to close cuticles that surround the hair shaft, which decreases penetration of active ingredients and tends to decrease the diameter of the hair, resulting in a decrease in the perception of body and fullness of the hair. Rousso et al's solution was to avoid low pH formulations, to formulate the polymers in a high pH medium on the basis that the combination lifts the hair cuticle and allows the polymers to penetrate into the hair to deposit under the cuticle and attach to the hair. When the hair is rinsed, the pH returns to normal or near normal levels and the cuticles flatten, but the deposited polymer blocks the cuticle from returning to its prior flattened state, trapping the polymer to give the hair fiber more body and fullness.
Others in the art have also avoided low pH formulations. For example, Collin in U.S. Pat. No. 5,964,227 ("Method and System for Treating Damaged Hair") contended that solutions applied to the hair having a pH lower than about 4.5 tend to tighten the coiled protein structure, and under conditions of extreme acidity such solutions cause the hair to become dry, brittle and almost crystalline in structure. Hirata in U.S. Pat. No. 6,521,219 ("Method Of Repairing or Restoring Damaged or Imperfect Hair")) hydrated hair shafts to open flaps of the cuticles layer, applied amino acids or peptides to the hair shafts to nourish the hair, then sandwiched the hair shafts between heated plates to compress the hair shafts under heat, causing the amino acids or peptides to penetrate through the cuticle layer and close the openings between the flaps.
By way of further background, attention is called to the following United States Letters patent references each of which is distinguishable from the teachings of the present invention, yet representative of at least an aspect of the state of the art.
Lange U.S. Pat. No. 5,132,107 describes a two phase shampoo allowing sequential application of substances/conditions to control dandruff. The hair is washed with a neutral or alkaline pH detergent composition, which may contain an antimycotic, and after rinsing out, the scalp is treated with a composition having an acid pH in the absence of detergents, but which may also contain an antimycotic.
Shih et al U.S. Pat. No. 5,139,770 and Grossman U.S. Pat. No. 5,711,943 both describe hair thickening or swelling gels or compositions containing at least polyvinylpyrrolidone (PVP) polymers, deionized water, fragrances, PEG-10 castor oil, citric acid, aminomethyl propanol (AMP), polyquaternium-11, glycerin, and/or methylparaben as a preservative.
Varco U.S. Pat. No. 6,010,690, describes a relatively high pH (alkaline) hair conditioning composition containing cationic guar hydroxypropyltrimonium chloride (Jaguar).
Deshpande et al U.S. Pat. No. 4,847,076, describes a method for enhancing the body of hair by applying to the hair a composition containing at least Jaguar.
Dupuis U.S. Pat. No. 5,679,328, describes a hair thickening composition containing a nonionic guar gum.
Balingit et al U.S. Pat. No. 4,243,659, Grollier et al U.S. Pat. No. 4,719,099, Bolich, Jr. et al U.S. Pat. No. 4,472,375, Varco U.S. Pat. No. 5,047,177, Tashjian U.S. Pat. No. 5,288,484, Bergmann U.S. Pat. No. 5,358,667, and Darkwa et al U.S. Pat. No. 5,376,364 all describe hair thickening or conditioning shampoos, compositions, formulas, etc. which contain at least an anionic or cationic thickening or conditioning agent.
Marsh et al U.S. Pat. No. 4,076,800, Mausner U.S. Pat. No. 4,126,674, Konrad et al U.S. Pat. No. 4,855,130, Jones U.S. Pat. No. 5,116,607, and Baylin U.S. Pat. No. 5,523,078 all describe hair thickening or conditioning compositions containing such ingredients as proteins, vitamins, and others used in formulations of the present invention).
Kripp et al U.S. Patent Application Publication No. 2003/0075197, Rath et al U.S. Pat. No. 5,972,322, Roberts U.S. Pat. No. 5,181,529, Cohen et al U.S. Pat. No. 5,393,305, and Cannell et al U.S. Pat. No. 6,486,105 all describe hair conditioning and/or thickening compositions having two-step or multi-step application processes.
Lukenbach et al Belli et al U.S. Patent Application Publication No. 2003/0158065, Belli et al U.S. Patent Application Publication No. 2002/0176836, and Giede et al U.S. Pat. No. 5,612,024, show various components of hair treating formulations.
Applicant herewith incorporates by reference the teachings and disclosures of the foregoing U.S. Patent Application Publication Nos. 2002/0176836; 2003/0075197; and 2003/0158065; and the foregoing U.S. Pat. Nos. 4,076,800; 4,126,674; 4,243,659; 4,472,375; 4,719,099; 4,847,076; 4,855,130; 5,047,177; 5,116,607; 5,139,770; 5,181,529; 5,288,484; 5,358,667; 5,376,364; 5,393,305; 5,523,078; 5,612,024; 5,679,328; 5,711,943; 5,964,227; 5,972,322; 6,010,690; 6,010,990; 6,348,439; 6,486,105; and 6,521,219.


A dynamic classifier for a coal pulverizer has an improved drive mechanism which is mounted on top of a pulverizer and concentric with the classifier axis of rotation and is directly controllable. The drive mechanism is a variable-speed DC or AC electric motor having a hollow motor shaft. The motor can produce classifier rotor rotational speeds of between 50 and 200 rpm. The classifier rotor is supported from the hollow motor shaft. A coal feed pipe passes through the hollow motor shaft and classifier rotor shaft into the pulverizer.

1. Field of the Invention
The present invention relates generally to the field of coal classifiers and pulverizers used to crush and pulverize and sort furnace fuel coal for combustion, and in particular to a new and useful dynamic classifier having a hollow shaft drive motor for the top section of a vertical axis coal pulverizer.
2. Description of the Related Art
The use of dynamic, or externally driven, coal classifiers to improve control of product particle size distribution is coming into increasing prominence as a supplemental technology to low NO.sub.x coal burners for reducing environmental pollutants. Dynamic coal classifiers are currently used to enhance the control of coal particle size and to improve the capacities of vertical-spindle pulverizers. A large percentage of dynamic coal classifiers are retrofit on existing pulverizers. High costs and difficult installation are the biggest barriers to widespread retrofitting of dynamic classifiers to existing pulverizers.
Vertical-spindle pulverizers usually receive raw coal through a feed pipe at the center of the grinding table rotation. The classifier is concentric with and rotates above and about the same grinding table center axis. Further, the coal output lines to the burners are usually positioned around the top of the pulverizer. The output lines are usually four or more pipes extending from the top of the pulverizer. This orientation of the input and output pipes on the pulverizer gives rise to special problems with respect to arranging the classifier's mechanical drive components.
Since the central axis of the classifier is occupied by the feed shaft, vertically-oriented motors used to drive the classifier rotation must be connected to the classifier rotor by V-belt or chain drives positioned to one side of the feed pipe. Alternatively, the motor may be connected to the classifier by gear-type speed reducers having large, hollow shafts. In each case, potential problems arise with respect to interference of drive components with planned or existing output pipes.
Speed reduction or control from the drive shaft of electric motors typically used to operate a classifier is required to obtain the low and variable rotation speeds desired. An electric or hydraulic motor in combination with speed reduction mechanisms is commonly used with classifiers to obtain operating rotational speeds of between 50 and 200 rpm.
These known classifiers and drive mechanisms have several drawbacks, including the high cost and difficult retrofit installation. The additional space occupied by the classifier drive mechanism is premium and sometimes difficult to obtain, such as when the height of the pulverizer must be increased as a result of the retrofit of the dynamic classifier.

Dynamic classifier with hollow shaft drive motor