An image forming system includes a first image forming apparatus, a second image forming apparatus disposed upstream in a sheet conveying direction and connected to the first image forming apparatus, and a post-processing apparatus that receives a sheet at a speed depending on a conveyance speed of a sheet discharged from the first image forming apparatus and that performs post-processing on the sheet. When a print job including a simplex image forming mode and a duplex image forming mode is to be executed, in the simplex image forming mode, a sheet is discharged in a reversed state to the post-processing apparatus. In the duplex image forming mode, the second image forming apparatus forms an image on a back side of a sheet, the first image forming apparatus forms an image on a front side of the sheet, and the sheet is discharged in a reversed state to the post-processing apparatus.

1. Field of the Invention
The present invention relates to an image forming system in which a plurality of printers are connected to one another in a sheet conveying direction.
2. Description of the Related Art
Generally, when a digital multifunction device is used as a printer, data is sent, starting from the first page, and, for example, pages of a five-page document are printed in the order of the first, second, third, fourth, and fifth pages. In order to output printed pages in correct order on a paper output tray, sheets are discharged with their image forming surfaces facing down. Therefore, an image forming apparatus has a sheet reversing mechanism for reversing or turning over a sheet.
Examples of the sheet reversing mechanism include a sheet reversing mechanism of a switch-back type in which, after a sheet is pulled back into a reverse conveying path that branches from a straight discharge conveying path, the conveying direction of the sheet is changed and the sheet is delivered in the changed conveying direction. In this case, a sheet interval corresponding to at least the distance required for switchback is needed to ensure that no collision of successively conveyed sheets occurs in the reverse conveying path. Accordingly, control is performed so that the speed at which sheets are conveyed from a fixing device and discharged from the main body of the image forming apparatus through the reverse conveying path is higher than that for straight discharge in order to increase productivity without increasing the sheet interval. This control allows the discharge interval for reverse discharge to be made equal to the discharge interval for straight discharge (see, for example, Japanese Patent Laid-Open No. 6-161185).
When the discharge speed is changed, a sheet post-processing apparatus that receives a discharged sheet also needs to change the conveyance speed in accordance with the discharge speed from the main body of the image forming apparatus.
For example, if the discharge speed from the image forming apparatus is higher than the speed at which the sheet post-processing apparatus receives a discharged sheet, sheets may be jammed between the sheet post-processing apparatus and the image forming apparatus, thus suppressing normal conveyance. It is therefore desirable that the sheet post-processing apparatus and the main body of the image forming apparatus be controlled so that the conveyance speed provided by the sheet post-processing apparatus and the discharge speed from the main body of the image forming apparatus are substantially equal.
A tandem image forming system is also known in which two printers are connected to each other to achieve high-efficiency two-sided (or duplex) image formation (see U.S. Pat. No. 7,024,152). The tandem image forming system provides duplex copying by forming an image on one side of a sheet using a first printer, reversing the sheet, and then forming an image on the other side of the sheet using a second printer. The time required for the above configuration is shorter than the time required for duplex copying with a single printer.
If the conveyance speed of a sheet received by the post-processing apparatus from the image forming apparatus is different from the conveyance speed of the preceding sheet, the post-processing apparatus also needs to change the conveyance speed. The post-processing apparatus changes the conveyance speed of a sheet after no sheets remain in the conveying path in the post-processing apparatus or after the preceding sheet has passes through rollers driven by the same motor in a receiving unit in the post-processing apparatus. That is, it takes time for the post-processing apparatus to be allowed to change the conveyance speed. Therefore, a large sheet interval is provided before and after the sheet conveyance speed is changed, resulting in a reduction in productivity.
In a tandem image forming apparatus, there is no need to change the conveyance speed if printing is performed only in a duplex image forming mode. However, printing may also be performed in a one-sided (or simplex) image formation mode and a duplex image forming mode. When both a simplex image forming mode and a duplex image forming mode are used, the post-processing apparatus needs to change the conveyance speed. In this case, the benefits of increasing productivity due to duplex image formation being performed using a tandem image forming system are not sufficiently taken advantage of.

Image forming system and printer controller


An example method includes creating, by a computing system and in response to user input, one or more virtual master devices and a plurality of virtual leaf devices in a virtual network system; selecting, by the computing system, data from one or more of real-time clock offset data, prerecorded clock offset data, or synthetically generated clock offset data; executing, by the computing system, a time synchronization simulation by applying a predefined clock offset generation algorithm to the selected data; and outputting, by the computing system, data indicative of results of the time synchronization simulation.

A synchronization system, in general, synchronizes clocks of multiple computing devices based on the clock of a chosen master device (also referred to as a "primary" device or a "leader" device). The master device is a computing device that gets time synchronization data from other master devices or intelligent engines deployed either inside or outside of the synchronization system, such as a global positioning system (GPS). The typical synchronization system has one or more layers of master devices with other end devices (also referred to as "replica" devices or "follower" devices) connected to at least one master device. Master devices are connected to the more precise sources of timestamps. In some implementations, master devices may belong to a service provider and can be designed to support precise time processing, while end devices may belong to the service client and receive timestamp offsets from master devices. These master and end devices can be chosen arbitrarily or assigned by the network.
In many applications, including but not limited to financial, scientific, military, programmatic advertising, and gaming industries, time synchronization may be beneficial. For instance, such knowledge would be used to define trade orders in high-frequency trading systems and gamers' responses in multi-user games.


A drawer pull-out guide including a first guide rail and a second guide rail displaceably supported relative to one another in a longitudinal direction of the guide rails between a closed position and an open position. A guide body is supported between the guide rails, and the guide rails are guidable relative to one another in a lateral direction in a mounted position of the drawer pull-out guide by the guide body. At least one of the guide rails includes a protrusion bearing against the guide body in the open position of the guide rails, so that at least in that region, in which the guide body and the protrusion bear against each other, the guide rails are arranged without clearance relative to one another in the lateral direction.

The present invention relates to a drawer pull-out guide, comprising a first guide rail and a second guide rail displaceably supported relative to one another in a longitudinal direction of the guide rails between a closed position and an open position. A guide body is supported between the guide rails, the guide rails being guidable in a lateral direction relative to one another in a mounted position of the drawer pull-out guide by the guide body.
With drawer pull-out guides, the lateral stability is a relevant quality criterion, and the lateral stability can usually be improved be specially formed guide rails and/or by running wheels for laterally guiding the guide rails. However, the lateral stability is significantly reduced the more the drawer is extended relative to a furniture carcass. In the fully extended condition of the drawer pull-out guide, leverage forces occur upon an application of force on the extended guide rail. These leverage forces intensify a lateral clearance between the guide rails or a tilting movement of the guide rails about an axis extending in the longitudinal direction of the guide rails. The lateral clearance of the extended drawer is additionally increased when the construction width of the drawer is increased. However, an undue lateral clearance of the drawer pull-out guide makes a rather poor impression to a person.
Measures for improving a lateral stability of receptacles are disclosed, for example, in EP 1 321 094 A1, EP 1 323 372 A2, U.S. Pat. Nos. 4,315,661 and 4,119,377.


A filter for separating a flowing fluid containing charged particles into two streams, one essentially free of particles and one laden with particles, includes a main conduit having an inlet at one end for receiving the flowing fluid, and having two outlets downstream of the one end for dividing the flow into two outlet flow paths. A pair of electrodes between which the fluid flows, is located in the main conduit upstream of the outlets; and each of the outlets is associated with a respective electrode. Voltage sources are connected to the electrodes such that one is more positive than the other for establishing, in the fluid flowing between the electrodes, an electric field transverse to the direction of flow whereby the particles in the field are attracted toward one of the electrodes and travel into the outlet associated therewith. A dielectric coating of release material in the form of a fluorosilicone polymer is applied to the surface of the one electrode for inhibiting plating-out of particles thereon while fluid flows in the conduit.

U.S. Pat. No. 4,737,268 discloses a particle classification system in which a liquid stream containing different types of particles is introduced into an enclosed channel subjected to a field gradient that is transverse to the direction of flow. The different types of particles respond differently to the field and are segregated into different flow substreams within the channel according to the effect of the field on the particles. These substreams are intercepted at spatially displaced positions in order to recover the different particles.
This principle of particle separation would be useful in connection with liquid toner based electrophotographic copying machines for filtering charged toner particles from the toner liquid for these machines. In these types of copying machines, an electrostatic latent image is formed on a photoconductive carrier movable into proximity with a developer electrode held at a voltage intermediate the voltages on the carrier representative of background and information portions of the image. Liquid toner, comprising dielectric carrier liquid containing charged toner particles, is applied between the carrier and the developer electrode. As regions of the carrier associated with background portions of the image move past the developer electrode, the local electric field is directed toward the electrode and charged toner particles in the vicinity are drawn toward the developer electrode. As regions of the carrier associated with information portions of the image move past the electrode, toner particles in the vicinity are drawn to and are plated-out on such regions thereby developing the latent image on the carrier into a visible image.
After the image is developed, the carrier moves to a transfer station where the developed image is transferred to a receiving sheet. Thereafter, the carrier is cleared of any residual toner particles, charged to a high voltage at a charging station, and then moved to an image transfer station where another image is optically projected onto the carrier. The process described above then repeats.
It is often useful in liquid toner based electrophotographic copying machines to process the liquid toner to recover liquid carrier substantially free of toner particles. To this end, a separation system similar to that disclosed in the '268 patent referred above can be utilized. In such case, toner laden liquid toner would pass through a conduit that divides the flow into two separate flow paths just downstream of a pair of electrodes that establish a unidirectional field transverse to the direction of flow. If the toner is negatively charged, the electric field urges the particles towards the positive electrode increasing the concentration of particles in the fluid adjacent that electrode. Thus, a flow pattern is created which carries most of the particles that entered the conduit into the flow path adjacent the positive electrode. The remainder of the liquid flowing through the other of the flow paths will be substantially free of toner particles.
The basic problem with this arrangement is the plating-out of toner particles on the positive electrode which has a two-fold effect: a local neutralization of the electric field due to the presence of the negatively charged particles on the positive electrode, and a physical reduction in the flow path. Thus, a periodic deplating operation has to be carried out. While techniques for periodically deplating the positive electrode are available (e.g., see U.S. Pat. No. 4,168,329, the disclosure of which is hereby incorporated by reference), the necessity for this procedure adds to the complexity and cost of the equipment.
It is therefore an object of the present invention to provide a new and improved field assisted filter, and an electrophotographic copying machine using the same, which eliminates or substantially reduces the need for deplating the electrode of the filter.

Field assisted filter and electrophotographic copying machine using the same


Techniques are described herein for automatically synthesizing programs that include one or more functions in a spreadsheet programming language. A method includes: receiving a first example including input provided in a first cell in a spreadsheet; automatically synthesizing a plurality of candidate programs including a first set of candidate programs consistent with the first example, wherein each candidate program in the first set of candidate programs comprises at least one function in a spreadsheet programming language and, when the candidate program is executed, the candidate program generates output that matches the first example; ranking the plurality of candidate programs; and storing a highest-ranked program of the plurality of candidate programs in association with the first cell in the spreadsheet.

Spreadsheet applications may implement a spreadsheet programming language that includes various functions that operate on data in a cell or range of cells in a spreadsheet and/or on other inputs in order to produce various outputs. Non-limiting examples of functions in a spreadsheet programming language include sum, count, average, length, concatenate, maximum, minimum, and lookup functions.
Users may manually enter data into a spreadsheet that could be obtained programmatically. For example, a user may manually enter last names into a column in a first table that could be obtained instead by using a function in a spreadsheet programming language to extract the last names from a column in a second table that stores full names. This manual approach, however, may be an inefficient use of user time and computer storage resources, as it may result in excessive data entry, client device usage, and duplication of the same data in multiple places in a spreadsheet. Additionally, when the underlying data changes in one location (e.g., a user's last name changes), the change must be manually propagated to all places in the spreadsheet where the data is used.
Users who are not programmers or experienced spreadsheet application users may be unaware of or uncomfortable with using functions in the spreadsheet programming language that are usable to programmatically obtain data to populate certain cells in a spreadsheet. Additionally, users may not understand how to combine together multiple functions in the spreadsheet programming language to form a program to obtain data to populate certain cells in a spreadsheet. Other users may be able to write their own programs that use multiple functions in the spreadsheet programming language to obtain data, but the programs that they write may be inefficient solutions that require excess processing and memory resources compared to more efficient solutions for obtaining the same data. Moreover, manually crafting the programs can often take an extended amount of time (e.g., to identify appropriate function(s), for trial and error, etc.) and, as a result, can lead to excess usage of power resources and/or other computational resource(s) of a client device used in manually crafting the programs. This can be exacerbated when the client device has a relatively small display and/or a software keyboard, both of which can prolong the amount of time needed to craft the programs.

Synthesizing programs in a spreadsheet programming language


An improved nitrogen laser includes two oppositely disposed discharge electrodes contained within a resonant chamber that is supplied with a mixture of nitrogen gas and a substantially small amount of electronegative gas. The mixture used within the chamber makes it possible to operate the nitrogen laser at a high voltage output and a higher frequency rate.

1. Field of the Invention
The present invention relates to an improved nitrogen laser and, more particularly, to an improved gaseous mixture apparatus for supplying the same for use in nitrogen lasers.
2. Description of Related Art
Nitrogen lasers are known in the prior art, as shown in FIG. 4. Such a laser operates by providing a high voltage pulse between two oppositely disposed electrodes, thereby bringing about a discharge excitation, which can be seen as area A on FIG. 4. Nitrogen gas enters through an inlet port 3 into an excitation chamber 2 containing the two discharge electrodes 1 and 1'. When the electrodes discharge, nitrogen molecules coming into the chamber 2 from inlet port 3 are ionized by the discharge pulse. The nitrogen ions will subsequently recombine to form neutral nitrogen molecules. This recombination can take a significant period of time to occur. Further, the recombination will also occur on the surface of the discharge electrodes and along the inner walls of the chamber 2. Therefore, a large number of nitrogen ions will remain within the discharge chamber and between the electrodes after each discharge pulse. This leads to a lower energy potential between the discharge electrodes, making it difficult for the nitrogen ions to reach sufficient energy levels to become nitrogen molecules. Also, the presence of a large number of nitrogen ions yields a proportionately lower amount of nitrogen molecules. This proportionately lower amount of nitrogen molecules renders the operation or the transmission of the nitrogen laser inherently more difficult. Therefore, using the construction of lasers shown as FIG. 4, the recombination of the nitrogen ions takes a sufficiently long period of time, so as to make impossible the operation of a high repetition laser, such as a 1-kHz repetition rate.
FIG. 5 charts the power output of a nitrogen laser of FIG. 4. As can be seen, the laser has an initial poor stability over a period of time. Furthermore, FIG. 5 shows a decrease in the total mean output of the laser over the period of time. FIG. 5 employs a nitrogen and gas flow rate of 3 liters per minute.
FIG. 6 shows an output of the laser shown in FIG. 4 at a pulse rate of 1 kHz. Thus, the stability during this time period under the stated conditions can be seen as being .+-.25%.
In order to carry out the operation of a high repetition laser, it is necessary to keep the chamber 2 supplied with a fresh supply of nitrogen gas N.sub.2. However, this requirement leads to increased consumption of N.sub.2 gas to such an extent that a dramatic increase in the cost of operating the conventional nitrogen laser is seen. Accordingly, a nitrogen laser capable of operating at a high repetition rate, exceeding 100 Hz, has not been introduced onto the market, and there is a need in the prior art to provide for an improved nitrogen laser that resolves the above problems.

High repetition nitrogen laser assembly using a nitrogen-electronegative gas mixture


A latch for securing an actuator arm of a hard disk drive. The latch has a catch portion that can engage a latch portion of the actuator arm. The latch also has a pusher portion and a crash stop portion that engage the actuator arm during movement into a latched position and prevent the latch from rebounding away from the arm. The pusher and crash stop portions eliminate the need for a separate crash stop in the disk drive. Eliminating the separate crash stop component reduces the complexity and cost for mass producing the disk drive.

1. Field of the Invention
The subject matter disclosed generally relates to the field of hard disk drives.
2. Background Information
Hard disk drives contain a plurality of transducers that are magnetically coupled to rotating magnetic disks. The transducers can write and read information onto the rotating disks by magnetizing and sensing the magnetic field of the disks, respectively. The transducers are integrated into heads that are part of a head gimbal assembly (HGA). The HGAs are typically attached to an actuator arm that is pivotally mounted to a base plate of the drive.
Information is typically stored within a plurality of data sectors. The data sectors are located within annular tracks of the disks. The actuator arm has a voice coil that is coupled to a magnet assembly mounted to the base plate. The voice coil and magnet assembly together create a voice coil motor. The voice coil motor can be energized to pivot the actuator arm and move the transducers to different annular tracks of the disks.
Hard disk drives are typically assembled into computer systems such as a portable computer. Movement of the portable computer may induce a rotational acceleration of the disk drive. The rotational acceleration of the disk drive may cause the actuator arm to move about the drive and damage disk drive components. There have been developed a number of latches that secure the actuator arm and prevent undesirable arm movement. The latch is typically engaged when the heads are moved away and unloaded from the disks.
FIG. 1 shows a magnetic latch 1 that can secure an actuator arm 2. The magnetic latch 1 is adjacent to a magnet assembly 3 that is coupled to a voice coil 4 of the arm 2. The actuator arm 2 includes a steel pin 5 that is magnetically attracted to the latch 1. The attractive magnetic force between the pin 5 and latch 1 maintains the position of the actuator arm 2. The actuator arm 2 can only be separated from the latch 1 by providing enough current to the voice coil 4 to create a torque sufficient to overcome the magnetic force. This requires additional power for the hard disk drive, a criteria that is undesirable when used in a portable computer. Additionally, the use of a magnetic latch 1 may require complex actuator speed control that increases the software processing overhead of the drive.
FIGS. 2-4 show an inertia latch 10 that can secure an actuator arm 11 when the disk drive has clockwise rotational acceleration. The inertia latch 10 is normally biased in an open position away from the actuator arm 11. When the disk drive is not writing or accessing information the actuator arm 11 is rotated to park the heads 12 on a ramp 13. The arm 11 also engages a crash stop 14. When the disk drive has a clockwise rotational acceleration the actuator arm 11 moves in a counterclockwise direction. The latch 10 also moves in a counterclockwise direction until a latch hook 15 extends into a notch 16 of the actuator arm 11 as shown in FIG. 3 to secure the arm 11.
As shown in FIG. 4, the latch 10 will move back to the open position when the disk drive is no longer rotationally accelerating. If the hard disk drive has a counterclockwise rotational acceleration, the actuator arm 11 will swing past the latch 10 in a clockwise direction and possibly land on the disks (not shown). This type of latch 10 will not secure the actuator arm 11 for counterclockwise rotational acceleration.
FIGS. 5-7 show a dual lever latch 20 which has a large latch arm 21 that can move a small latch arm 22 into an actuator arm 23. The small latch arm 22 will engage the actuator arm 23 whether the disk drive has clockwise or counterclockwise rotational acceleration. When the disk drive is rotating in a clockwise direction the large latch arm 21 moves in a counterclockwise direction and a first latch pin 24 pulls the small latch arm 22 into the actuator arm 23 as shown in FIG. 6. When the disk drive is rotating in a counterclockwise direction the large latch arm 21 moves in a clockwise direction and a second latch pin 25 pushes the small latch arm 22 into the actuator arm 23 as shown in FIG. 7. The latch 20 will secure the arm 23 regardless of the rotational acceleration direction. This design requires multiple latch components that increases the complexity and cost of mass producing the disk drive.
FIG. 8 shows an impact rebound single lever bi-directional latch 30. The latch 30 has a catch 31 that can engage a corresponding hook portion 32 that extends from an actuator arm 33. When engaged, the hook 32 and catch 31 secure the actuator arm 33 when the disk drive is subjected to a rotational acceleration. The latch 30 includes a tab 34 that is coupled to a magnet (not shown). The tab 34 is attracted to the magnet to pull the latch 30 away from the hook 32 to detach the actuator arm 33.
When the disk drive undergoes a clockwise rotational acceleration the actuator arm 31 and latch 30 will move in a counterclockwise manner. The actuator arm 36 may strike the latch 30 before the hook 32 and catch 31 have engaged. This premature contact may cause the latch to rebound and rotate back in the clockwise direction away from the actuator arm 33. The disk chive includes a crash stop 35 which limits the movement of the latch 30 in the clockwise direction so that the hook 32 will still slide into the catch 31. Having separate latch and stop parts increases the complexity and cost of mass producing the drives. It would be desirable to minimize the number of parts in the latch assembly.
A latch for an actuator arm of a hard disk drive. The latch includes a catch portion, a pusher portion, and a crash stop portion that is located between the catch and pusher portions.

Pawl latch for ramp loading hard disk drivers


A powerful, scaleable, and reconfigurable image processing system and method of processing data therein is described. This general purpose, reconfigurable engine with toroidal topology, distributed memory, and wide bandwidth I/O are capable of solving real applications at real-time speeds. The reconfigurable image processing system can be optimized to efficiently perform specialized computations, such as real-time video and audio processing. This reconfigurable image processing system provides high performance via high computational density, high memory bandwidth, and high I/O bandwidth. Generally, the reconfigurable image processing system and its control structure include a homogeneous array of 16 field programmable gate arrays (FPGA) and 16 static random access memories (SRAM) arranged in a partial torus configuration. The reconfigurable image processing system also includes a PCI bus interface chip, a clock control chip, and a datapath chip. It can be implemented in a single board. It receives data from its external environment, computes correspondence, and uses the results of the correspondence computations for various post-processing industrial applications. The reconfigurable image processing system determines correspondence by using non-parametric local transforms followed by correlation. These non-parametric local transforms include the census and rank transforms. Other embodiments involve a combination of correspondence, rectification, a left-right consistency check, and the application of an interest operator.

1. Field of the Invention
The present invention relates generally to data processing. More particularly, the present invention relates to determining correspondence between related data sets, and to the analysis of such data. In one application, the present invention relates to image data correspondence for real time stereo and depth/distance/motion analysis.
2. Description of Related Art
Certain types of data processing applications involve the comparison of related data sets, designed to determine the degree of relatedness of the data, and to interpret the significance of differences which may exist. Examples include applications designed to determine how a data set changes over time, as well as applications designed to evaluate differences between two different simultaneous views of the same data set.
Such applications may be greatly complicated if the data sets include differences which result from errors or from artifacts of the data gathering process. In such cases, substantive differences in the underlying data may be masked by artifacts which are of no substantive interest.
For example, analysis of a video sequence to determine whether an object is moving requires performing a frame-by-frame comparison to determine whether pixels have changed from one frame to another, and, if so, whether those pixel differences represent the movement of an object. Such a process requires distinguishing between pixel differences which may be of interest (those which show object movement) and pixel differences introduced as a result of extraneous artifacts (e.g., changes in the lighting). A simple pixel-by-pixel comparison is not well-suited to such applications, since such a comparison cannot easily distinguish between meaningful and meaningless pixel differences.
A second example of such problems involves calculation of depth information from stereo images of the same scene. Given two pictures of the same scene taken simultaneously, knowledge of the distance between the cameras, focal length, and other optical lens properties, it is possible to determine the distance to any pixel in the scene (and therefore to any related group of pixels, or object). This cannot be accomplished through a simple pixel-matching, however, since (a) pixels at a different depth are offset a different amount (this makes depth calculation possible); and (b) the cameras may have slightly different optical qualities. Since differences created by the fact that pixels at different depths are offset different amounts is of interest, while differences created as an artifact of camera differences is not of interest, it is necessary to distinguish between the two types of differences.
In addition, it may be useful to perform such comparisons in real-time. Stereo depth analysis, for example, may be used to guide a robot which is moving through an environment. For obvious reasons, such analysis is most useful if performed in time for the robot to react to and avoid obstacles. To take another example, depth information may be quite useful for video compression, by allowing a compression algorithm to distinguish between foreground and background information, and compress the latter to a greater degree than the former.
Accurate data set comparisons of this type are, however, computationally intensive. Existing applications are forced to either use very high-end computers, which are too expensive for most real-world applications, or to sacrifice accuracy or speed. Such algorithms include Sum of Squared Differences ("SSD"), Normalized SSD and Lapalacian Level Correlation. As implemented, these algorithms tend to exhibit some or all of the following disadvantages: (1) low sensitivity (the failure to generate significant local variations within an image); (2) low stability (the failure to produce similar results near corresponding data points); and (3) susceptibility to camera differences. Moreover, systems which have been designed to implement these algorithms tend to use expensive hardware, which renders them unsuitable for many applications.
Current correspondence algorithms are also incapable of dealing with factionalism because of limitations in the local transform operation. Factionalism is the inability to adequately distinguish between distinct intensity populations. For example, an intensity image provides intensity data via pixels of whatever objects are in a scene. Near boundaries of these objects, the pixels in a some local region in the intensity image may represent scene elements from two distinct intensity populations. Some of the pixels come from the object, and some from other parts of the scene. As a result, the local pixel distribution will in general be multimodal near a boundary. An image window overlapping this depth discontinuity will match two half windows in the other image at different places. Assuming that the majority of pixels in such a region fall on one side of the depth discontinuity, the depth estimate should agree with the majority and not with the minority. This poses a problem for many correspondence algorithms. If the local transform does not adequately represent the intensity distribution of the original intensity data, intensity data from minority populations may skew the result. Parametric transforms, such as the mean or variance, do not behave well in the presence of multiple distinct sub-populations, each with its own coherent parameters.
A class of algorithms known as non-parametric transforms have been designed to resolve inefficiencies inherent in other algorithms. Non-parametric transforms map data elements in one data set to data elements in a second data set by comparing each element to surrounding elements in their respective data set, then attempt to locate elements in the other data set which have the same relationship to surrounding elements in that set. Such algorithms are therefore designed to screen out artifact-based differences which result from differences in the manner in which the data sets were gathered, thereby allowing concentration on differences which are of significance.
The rank transform is one non-parametric local transform. The rank transform characterizes a target pixel as a function of how many surrounding pixels have a higher or lower intensity than the target pixel. That characterization is then compared to characterizations performed on pixels in the other data set, to determine the closest match.
The census transform is a second non-parametric local transform algorithm. Census also relies on intensity differences, but is based on a more sophisticated analysis than rank, since the census transform is based not simply on the number of surrounding pixels which are of a higher or lower intensity, but on the ordered relation of pixel intensities surrounding the target pixel. Although the census transform constitutes a good algorithm known for matching related data sets and distinguishing differences which are significant from those which have no significance, existing hardware systems which implement this algorithm are inefficient, and no known system implements this algorithm in a computationally efficient manner.
In the broader field of data processing, a need exists in the industry for a system and method which analyze data sets to determine relatedness, extract substantive information that is contained in these data sets, and filter out other undesired information. Such a system and method should be implemented in a fast and efficient manner. The present invention provides such a system and method and provides solutions to the problems described above.


A method is proposed for correcting detector signals of a unit for reconstructing tomograms from projection data, in particular of a computer tomography unit, of a ray detector having a multiplicity of individual detector channels that form the projection data, attenuation values of individual X-rays being calculated after the passage through an examination object. In order to reconstruct the tomograms from attenuation values of the X-rays, the detector output signals are subjected to a nonlinearity correction before the calculation of the attenuation values.

Both in computer tomography and in all other methods that reconstruct tomograms from projection data, it is important that the detectors used to measure irradiation scanning an examination object exhibit as linear as possible a response to the detected radiation. Nonlinearities, in particular those that differ from measurement channel to measurement channel, lead to ring artifacts in the reconstructed image, and disturb the image quality.
This problem is addressed in the prior art both by using expensive detectors with high linearity, and by applying corrections to the already calculated attenuation values of the measured radiation.

Method for correcting detector signals of a unit for reconstructing tomograms from projection data


A protective sheath adapted to cover an elongate medical probe. The sheath includes an elongate sheath adapted to receive an insertion tube of a medical probe and isolate the insertion tube from body tissue and at least one light generating element mounted on the sheath.

Endoscopes are used to view internal tissue of humans, and for many other tasks. As sterilization of endoscopes is relatively difficult, disposable sheaths which cover an endoscope are often used to isolate the endoscope from the patient tissue, so as to avoid time-consuming cleaning and disinfection processes.
In many cases, in order to view the interiors of body cavities, there is a need for delivery of illumination to body cavities.
U.S. Pat. No. 6,449,006 to Shipp, the disclosure of which is incorporated herein by reference, describes an illumination system including a plurality of light emitting diodes (LEDs) for an endoscopic camera. The system includes twenty eight LEDs mounted on a ceramic substrate having a cylindrical aperture, which allows light from a viewed object to reach a lens of the endoscope.
U.S. Pat. No. 6,814,699 to Ross et al., the disclosure of which is incorporated herein by reference, describes an endoscope including an array of LEDs mounted on a substrate and covered by a common distal protective shield. The array may be mounted at the distal end of an insertion tube of the endoscope.
U.S. Pat. No. 6,551,240 to Henzler, the disclosure of which is incorporated herein by reference, describes an endoscope with illumination LEDs.
U.S. patent publication 2004/0064018 to Dunki-Jacobs et al., the disclosure of which is incorporated herein by reference, describes an endoscope that has an integrated light source and camera mounted at the distal end of the endoscope.
The above patent publications all describe endoscopes which are specifically planned with LEDs mounted thereon. Using the description of any of these patents requires replacing currently used endoscopes at a relatively high cost.
PCT publication WO2004/000107 to Couvillon, the disclosure of which is incorporated herein by reference, describes an endoscope with a sensor disposed at a distal end of the endoscope and a portable power source which can be disposed anywhere along the length of the endoscope but is preferably located at a proximal end of the endoscope.
U.S. Pat. No. 6,478,730 to Bala, the disclosure of which is incorporated herein by reference, describes a laparoscope having a disposable sheath which leads illumination within its walls to a distal end of the laparoscope. The leading of illumination through the walls of a thin protective sheath has encountered various technical problems.
U.S. Pat. No. 5,165,387 to Woodson, the disclosure of which is incorporated herein by reference, describes a disposable endoscope kit, which has a disposable light source for mounting at a proximal end of a channel of the endoscope kit, within the channel.


The invention relates to a pharmaceutical composition comprising cefuroximaxetil and at least one carrageenan selected from the group consisting of κ-carrageenan, λ-carrageenan and -carrageenan. The invention furthermore relates to pellets, to a multiparticulate, pharmaceutical dosage form and to a novel crystalline modification of cefuroximaxetil.

The invention relates to a pharmaceutical composition which contains cefuroximaxetil and ensures improved release of the active ingredient from dosage forms. The invention also relates to a stable crystalline modification of cefuroximaxetil.
Cefuroximaxetil (ATC code J01DA45) is broad spectrum antibiotic of the cephalosporin class which is conventionally administered orally. Administration of cefuroximaxetil is indicated in infections of the airways, of the urogenital tract and in otorhinolaryngeal infections. It may also be administered in soft tissue infections and infections of the bones and joints (c.f. L. J. Scott et al., Drugs 2001, 61, 1455-1500).
Cefuroximaxetil is the 1-acetoxyethyl ester of cefuroxime, i.e. of (6R,7R)-3-carbamoyloxymethyl-7-[(Z)-2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (c.f. U.S. Pat. No. 3,974,153 and U.S. Pat. No. 4,267,320; ATC code J01DA06). Where approved for pharmaceutical use, cefuroximaxetil conventionally comprises a mixture of two diastereomers. Processes for isolating the individual diastereomers are described in the prior art (c.f. DE-OS-27 06 413 and U.S. Pat. No. 5,063,224).
For the purposes of the description, cefuroximaxetil preferably comprises the pharmaceutically usable mixture of the diastereomers, as is for example defined in USP 23, pages 315/316. The two diastereomers are here present in an approx. 1:1 ratio. According to USP 23, a sample of the mixture of diastereomers is chromatographed. A peak rA then corresponds to the A isomer and a peak rB to the B isomer. According to USP 23, page 315, right hand column, the ratio of the diastereomers is then determined using the formula rA/(rA+rB). This ratio must be between 0.48 and 0.55.
The production of dosage forms which are suitable for administering cefuroximaxetil is associated with various problems. On the one hand, these problems are attributable to the chemical and physical properties of the active ingredient, in particular to its bitter flavour and its comparatively poor solubility, which is largely pH-independent in an aqueous medium. On the other hand, however, the physical properties of conventional solid dosage forms, in particular their rate of disintegration under physiological conditions also play an important part.
One substantial problem which is directly attributable to the properties of the active ingredient itself is the only slight solubility of cefuroximaxetil in an aqueous medium. It is particularly unfavourable in this connection that this slight solubility prevails not only in gastric juice, but also at pH values which correspond to the physiological pH values of the small intestine. It is precisely in the small intestine that cefuroximaxetil should in principle be as rapidly available as possible, as this is largely where it is absorbed.
The bioavailability of cefuroximaxetil is inter alia a function of its solubility. USP 23 describes a test on page 316 for determining the bioavailability of cefuroximaxetil. To this end, the solubility of the active ingredient from a standardised tablet formulation is determined in methanol. Those products in which at least 60% of the active ingredient is dissolved in 15 minutes and at least 75% of the active ingredient is dissolved within 45 minutes are approved.
Various solid modifications of cefuroximaxetil are known in the prior art which are distinguished inter alia by different solubility.
The amorphous form of cefuroximaxetil is conventionally used for the production of oral dosage forms (c.f. DE-OS 34 27 828, EP-A 107 276 and U.S. Pat. No. 4,562,181). However, use of the amorphous form is problematic. It is accordingly known that at 37° C. amorphous cefuroximaxetil forms a sparingly soluble gel layer on the external surface of the particles when it comes into contact with water, so considerably delaying active ingredient release.
Apart from the amorphous form of cefuroximaxetil, various crystalline modifications of cefuroximaxetil are known. It has been reported that these crystalline modifications have a lesser tendency to form a gel than the amorphous form. However, in comparison with the amorphous form, hitherto known crystalline modifications exhibit lower solubility and thus also reduced bioavailability.
GB-A-15 71 683 accordingly discloses a modification which is hereinafter denoted the "α-modification". An IR spectrum is disclosed in GB-A-21 45 409. The α-modification does not exhibit sufficient bioavailability for use as a pharmaceutical preparation; when tested according to USP 23, it does not achieve the specified minimum solubility. EP-A-757 991 discloses a modification which is hereinafter denoted the "β-modification". However, when determined in accordance with the standard method according to USP 23 page 316, the solubility of the active ingredient only amounts to somewhat over 40% after 45 minutes. EP-A-937 727 discloses a modification which is hereinafter denoted the "γ-modification". According to the disclosure of the document, 73.0% of the active ingredient are dissolved after 45 minutes (determined in accordance with the standard method according to USP 23, page 316). EP-A-937 727 furthermore discloses a hemihydrate which consists to an extent of approx. 95% of the R isomer.
Apart from its slight solubility, the bitter flavour of cefuroximaxetil also plays a part when formulating oral dosage forms.
Cefuroximaxetil is accordingly conventionally marketed in the form of film coated tablets (Elobact® and Zinnat®), which according to the manufacturers' instructions should not be crushed or chewed due to the bitter flavour of cefuroximaxetil. Other dosage forms are thus recommended for children below 5 years of age. Cefuroximaxetil is, for example, also marketed as a powder for suspension, the active ingredient being provided as a dry granular product. Shortly before the preparation is first taken, water is added to produce a suspension which can be stored in a refrigerator (+2° C. to +8° C.) for 10 days. Currently marketed powders for suspension contain a granular product of amorphous cefuroximaxetil, which is coated with stearic acid in order to mask the bitter flavour of the active ingredient (c.f. DE-OS-38 16 464). Despite the coating, this formulation still has an unpleasant, bitter flavour and so does not always meet with unreserved acceptance from children. The flavour even gets worse during storage of the suspension, as the coating softens over time. Furthermore, the bioavailability of cefuroximaxetil from this dosage form is approx. 30% lower than from comparable dosage forms with uncoated particles.
Apart from these difficulties due to the active ingredient, problems sometimes also occur which are determined not only by the active ingredient, but also by the dosage form.
Thus, even when the comparatively readily soluble amorphous cefuroximaxetil is used, in order to ensure sufficient bioavailability it is necessary for the dosage form, for example a film coated tablet, to disintegrate virtually instantaneously on contact with intestinal juice, such that the active ingredient particles may disperse and release the active ingredient rapidly without any appreciable gelation occurring. For this purpose, particles with a small diameter and large specific surface area are conventionally used for the production of film coated tablets.
The twice daily administration of cefuroximaxetil which is in principle desired entails a comparatively high active ingredient loading of the dosage forms. As is known, an elevated active ingredient loading may in particular be achieved with extruded pellets, which moreover comprise the desired smooth, preferably spherical form. A disadvantage of at these dosage forms is, however, that they usually have a very compact structure, which is primarily attributable to auxiliary substances such as microcrystalline cellulose (MCC). Due to their compact structure, these dosage forms do not disintegrate in an aqueous medium or at most disintegrate only very slowly, which may result in unwanted, greatly delayed release of cefuroximaxetil.
As a result, it is possible that release will occur to a considerable extent only in a lower portion of the intestine, so preventing adequate bioavailability of the active ingredient.
This low dissolution rate of the dosage form and the associated delayed release of the cefuroximaxetil is in particular observed when known spheronising agents, such as microcrystalline cellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose are used, which, while indeed giving rise to pellets of the desired shape and with a narrow particle size distribution, result in delayed release of the active ingredient.
This is in particular observed in extruded pellets which have been produced with the assistance of the stated spheronising agents, once an existing coating, which may be resistant to saliva and/or gastric juice and also has a flavour neutralisation function, has dissolved. After the pH-dependent dissolution of the coating in the small intestine, such pellets disintegrate only very slowly, even in the presence of disintegrants and surfactants, so delaying the release of the cefuroximaxetil and limiting bioavailability.
Apart from the in any event comparatively poor disintegration characteristics of such pellets, an additional complicating factor with cefuroximaxetil is that, when the amorphous form of the active ingredient is used, release is complicated by gelation and, when known crystalline modifications are used, release is reduced as a result of their lower solubility. The bioavailability of the active ingredient from such pellets is not satisfactory; pellets are, for example, known which release only 20-30% of the active ingredient after 60 min.

This patent is subject to a terminal disclaimer.

Dosage form with improved release of cefuroximaxetil


The present invention relates to low dielectric materials essential for a semiconductor having high density and high performance of the next generation, particularly to a process for preparing a porous interlayer insulating film having low dielectric constant containing pores with a size of a few nanometers or less.

(a) Field of the Invention
The present invention relates to a low dielectric material essential for a next generation semiconductor device having high density and high performance, and particularly to a process for preparing a porous interlayer insulating film having low dielectric constant containing pores having a size of a few nanometers or less.
(b) Description of the Related Art
The semiconductor industry is moving toward increasing device complexity, requiring shrinking geometric dimensions and higher component integration with greater dimensional densities in integrated circuit devices, e.g. memory and logic chips. This has led to an increase in the number of wiring levels and a reduction in the wiring pitch to increase the wiring density. Current leading-edge logic processors have 6-7 levels of high density interconnect, and interconnect line width is scheduled to decrease to 0.1 xcexcm around the year 2005.
As device dimensions shrink to less than 0.25 xcexcm, the propagation delay, crosstalk noise, and power dissipation due to resistance-capacitance (RC) coupling become significant. The smaller line dimension increases the resistivity of metal wires, and the narrow intermetal spacing increases the capacitance between the metal wires. Thus although the speed of the device will increase as the feature size decreases, the interconnect delay becomes the major fraction of the total delay and limits the overall chip performance. Accordingly, in order to prepare a chip having high speed, a conductor having a low resistance and a dielectric material having low dielectric constant should be used. In addition, the use of a low dielectric material can remarkably decrease the power dissipation and crosstalk noise.
Recently, several semiconductor device manufacturers have put test products on the market that show improvement in their performance of 20% or more, using copper wiring with high electric conductivity instead of using the conventional aluminum wiring. Recently they shift to use of new materials that exhibit low dielectric constant performance, for use in interconnects. If the dielectric films between interconnect layers in integrated circuit can make use of these materials, the effect on operating speed will be the same as that which resulted with the switch from aluminum to copper technology. For instant, if the dielectric constant of the dielectric material is changed from 4.0 to about 2.5, IC operating speed will be improved by about 20%.
The interlayer dielectric material used in semiconductor integrated circuit devices is predominantly SiO2, which is generally formed using chemical vapor deposition (CVD) or plasma enhanced techniques and has the requisite mechanical and thermal properties to withstand various processing operations associated with semiconductor manufacturing. The relative dielectric constant of a SiO2 material varies with the conditions under which a dielectric is formed; that of silicon thermal oxidation films, which have the lowest dielectric constant, is of the order of 4.0. Attempts have been made to reduce the dielectric constant by introducing fluorine atoms into an inorganic film deposited by CVD. However, the introduction of fluorine atoms in large amounts decreases the chemical and thermal stability, so the dielectric constant achieved in actual practice is of the order of 3.5. Fluorinated oxides can provide an immediate near-term solution and a shift to new types of insulating materials with sub-3 dielectric constant may be required.
One class of candidate is organic polymers, some of which have a dielectric constant less than 3.0. Incorporating fluorine into such organic polymers is known to further lower the dielectric constant. Most organic polymers do not, however, possess the physico-chemical properties required for on-chip semiconductor insulation, particularly thermal stability and mechanical properties (sufficient to withstand back end of the line fabrication temperatures within the range of 400xcx9c450xc2x0 C.). Few organic polymers are stable at temperatures greater than 450xc2x0 C. They also have a low glass transition temperature and thus elasticity thereof remarkably decreases at high temperature, and they have a very high linear expansion coefficient Since temperature rises to up to 450xc2x0 C. during semiconductor IC integration and packaging processes, the resulting low thermal stability and elasticity and high linear expansion coefficient can deteriorate the reliability of the device.
Recently in order to solve thermal stability problems of organic polymers, the development of organic silicate polymers using a sol-gel process has emerged. In particular, organic SOG(Spin On Glass) has been proposed for use as interlayer dielectrics in which the side chain of an organic component (an alkyl group such as methyl) is bonded to the backbone chain of a siloxane bond. It has a lower dielectric constant, e.g., the range of about 2.7xcx9c3.2, than conventional glasses.
The development of interlayer insulating materials having a low dielectric constant of 2.5 or less is necessary for developing devices of high performance and high density of the next generation, and in order to do this, the introduction of air having a dielectric constant of 1 into materials having dielectric constant of 3.0 to 2.5 is needed.
Brinker et al., U.S. Pat. No. 4,652,467 present a method of forming porous dielectric films on substrates. The process uses a sol-gel technique for depositing porous films with controlled porosity and pore size, wherein a solution is deposited on a substrate, gelled, and then cross-linked and densified by removing the solvent through evaporation, thereby leaving a porous dielectric. Dielectric formed by this method, generally referred to as xerogels, has pores that are generally interconnected, rather than being isolated cells. Dielectrics are typically 10xcx9c50% porous with a permanent film thickness reduction of at least 20% during drying.
Sakamato et al. U.S. Pat. No. 5,103,288 report a method to fabricate low density dielectric films on a substrate containing 50% to 80% porosity. The porous insulating film is typically formed by applying a mixture of an acidic oxide and basic oxide on a substrate, heat-treating to precipitate the basic oxide, and then dissolving out the basic oxide. However dissolving all the basic oxide out of such a dielectric film may be difficult and several of elements described for use in the basic oxide such as sodium and lithium can contaminate electronic devices.
Nguyen et al., Chem. Mater. 1999, 11, 3080xcx9c3085 describe a method to fabricate porous organosilicates useful for on-chip insulator applications by using precondensed organic silicate and thermally labile polymers. The process involves spin coating a mixture of the matrix material and the thermally labile polymers followed by thermal curing to initiate vitrification and decomposition of the polymers. The microphase-separated domain is formed during the condensation of the organic silicate. However, since the polymers used to form pores have low compatibility with a matrix resin, phase-separated domain tend to become large, and if the contents of polymers increase, an opaque film will easily form. In addition, it may be difficult to generate very small sized pores due to the use of polymers, and to form pores of a uniform size due to the distribution of molecular weight.
Mikoshiba et al., J. Mat Chem., 1999, 9, 591xcx9c598, describe the preparation of porous films containing angstrom size pores. Copolymers comprising methyl(trisiloxysilyl) units and alkyl(trisiloxysilyl) units are spin-coated and cured at 250xc2x0 C. to provide rigid organic polysilicates. Then films are heated up to 450 or 500xc2x0 C. to remove thermally labile alkyl groups and pores are formed corresponding to the sizes of the substituents. Trifluoropropyl, cyanoethyl, phenethyl and propyl groups are investigated as the thermally labile substituents. Only the trifluoropropyl group works well under the limitation of final curing temperatures up to 450xc2x0 C. or 500xc2x0 C., the pores collapsing for films bearing other substitiuents.
The present invention is made in consideration of the problems of the prior art, and it is an object of the present invention to provide a process for preparing a wiring interlayer insulating film having very low dielectric constant that can make the speed of a semiconductor device higher, decrease consumption of electric power, and remarkably decrease interference between metal wirings.
It is another object of the present invention to provide a process for preparing wiring interlayer insulating film having very low dielectric constant containing pores with a size of a few nanometers or less.
It is another object of the present invention to provide a process for preparing wiring interlayer insulating film having very low dielectric constant in which phase-separaton is reduced.
In order to achieve these objects, the present invention provides a process for preparing porous wiring interlayer insulating film having very low dielectric constant for a semiconductor comprising the steps of:
a) preparing a mixed complex of pore-forming organic molecules and matrix resin;
b) coating the mixed complex on a substrate; and
c) heating the mixed complex to remove the organic molecules therefrom, thereby forming pores inside the complex.
The present invention also provides an interlayer insulating film for metal wiring of a semiconductor prepared according to the process.
The present invention also provides a semiconductor device comprising the interlayer insulating film for metal wiring prepared according to the process.
The present invention provides a low dielectric resin composition useful as e.g. a resin composition capable of forming a uniform dielectric film having a nanopore useful for electrical insulating insulating layer on electrical devices.
The present invention provides a low dielectric resin composition comprising the following components (a) and (b), and a process for its production. A dielectric film formed by the resin composition of the present invention is a film having a dielectric constant at most 3.3, preferably less than 3.0, more preferably less than 2.7, wherein a cured product prepared by the component (a) and component (b) are uniformly cross-linked by a chemical reaction, followed by the removal of the organic part of the component (b). According to this process since phase-separation is inhibited compared to the conventional process, an insulating film that has excellent processability, isotropic structure, and very small pores with molecular size can be formed.
(a) organosilane component includes at least one compound selected from the group consisting of
(a-1) organosilane of the Chemical Formula 1: R1mR2nSiX4xe2x88x92mxe2x88x92n (where each of R1 and R2 which may be the same or different, is a non-hydrolysable group, X is a hydrolysable group, and m and n are integers of from 0 to 3 satisfying 0xe2x89xa6m+nxe2x89xa63) and/or a partially hydrolyzed condensate thereof
(a-2) organic bridged silane of the Chemical Formula 2: R3pY3xe2x88x92pSixe2x80x94Mxe2x80x94SiR4qZ3xe2x88x92q (where each of R3 and R4 which may be the same or different, is a non-hydrolysable group, Y and Z which may be the same or different, is an hydrolysable group, M is an alkylene or arylene group, and p and q are integers of from 0 to 2 and/or a cyclic oligomer with organic bridge unit (Sixe2x80x94Mxe2x80x94Si).
and/or a partially hydrolyzed condensate thereof
(b) pore-forming component containing decomposable organic molecules by thermal curing with/without irradiation.
As the component (a) suitable silane compounds used in the present invention include a silane precursor comprising silicon, oxygen, carbon and hydrogen, and an organic polysilicate prepolymer prepared therefrom. It is preferably selected from the group consisting of a compound represented by the following Chemical Formula 1, Chemical Formula 2, and a mixture thereof, or an organic silicate prepolymer prepared therefrom. In the Formula 1, each R1 and R2 is independently hydrogen, alkyl such as methyl, ethyl, propyl, butyl, or others, fluorine-containing alkyl group such as trifluoromethyl, trifluoropropyl or others, alkenyl such as vinyl, allyl, or others, or aryl such as phenyl. Those alkyl groups may be linear or branched, X is independently hydrolysable group, halide such as chlorine, alkoxy such as methoxy, ethoxy or propoxy, acyloxy such as acetoxy, or, others. Although there is no particular limitation with respect to the functional group R1, R2 and X, it is more preferred that R1 and R2 are independently hydrogen, alkyl or phenyl and X is an alkoxy group. Some examples of the component (a-1) organosilane include tetraalkoxysilane, monoalkyltrialkoxysilane, dialkyldialkoxysilane, trialkylmonoalkouysilane, trialkoxysilane, monoalkyldialkoxysilane, a mixture thereof etc. The partially hydrolyzed product of the organosilane precursor can be obtained by allowing a monomer or an oligomer to react in an organic solvent after addition of water and a catalyst at a temperature not higher than the boiling point of the organic solvent for a state time. In the Formula 2, each of R3 and R 4 is independently hydrogen, alkyl such as methyl, ethyl, propyl, butyl, or others, fluorine-containing alkyl group such as trifluoromethyl, trifluoropropyl or others, alkenyl such as vinyl or allyl, or aryl such as phenyl, Y and Z are independently hydrolysable group, halide such as chlorine, alkoxy such as methoxy, ethoxy or propoxy, acyloxy such as acetoxy, or others. When R 3 and/or R 4 are alkenyl, it may be further bridged by a method of hydrosiylation reaction described below. Organic bridged unit, M may be alkylene or phenylene, preferably methylene, ethylene, propylene, phenylene, or a mixture thereof.
Synthesis of the organic bridged silane is afforded from hydrosilylation reaction of alkenyl containing silane or Grignard reaction of alkylhalide containing silane. In hydrosilylation, reaction was conducted between a silane precursor containing a Sixe2x80x94H group with a silane precursor containing aliphatic unsaturated carbon (xe2x80x94CHxe2x95x90CH2) in presence of a catalyst or free radical initiator. Preferred catalysts are the platinum group metal containing catalysts. They can be any of those known in the art to effect a hydrosilylation reaction between a silicon-bonded hydrogen atom and an unsaturated carbon-carbon bond, e.g. platinum, palladium, osmium, iridium, and ruthenium etc. A transition metal catalyst such as platinum, or a free radical initiator is employed in an effective amount, depending on the particular catalyst used.
Cyclic oligomer with organic bridge (Sixe2x80x94Mxe2x80x94Si) unit can be synthesized by the hydrosilylation reaction of a oligomer of ring structure (I) and/or ring structure (II), i.e. an addition reaction between a silane precursor containing a Sixe2x80x94H group with a cyclic oligomer (I) and/or (II) containing aliphatic unsaturated carbon (xe2x80x94CHxe2x95x90CH2) in presence of a catalyst or free radical initiator,
where L1 is independently alkenyl such as vinyl or allyl, L2 is independently hydrogen, alkyl such as methyl, ethyl or others, or aryl such as phenyl, M1 is independently alkenyl such as vinyl or allyl, M2 is independently hydrogen, alkyl such as methyl, ethyl or others, or aryl such as phenyl.
As the component (b) a pore-forming material used in the present invention is radiation decomposable or preferably thermally decomposable. The radiation decomposable small molecules decompose upon exposure to radiation; e.g, ultraviolet, x-ray, electron beam or the like. The thermally decomposable small molecules used as a pore-forming material f have at least one silyl functional group at the end, so that a pore-forming material can be connected by a covalent bonding with the component (a). The pore-forming material component (b) may be mixed with partially hydrolyzed condensate prepared from the component (a), or it can be added when preparing a partially hydrolyzed condensate of the component (a). The pore-forming material is an organic molecules with a silyl group, preferably at the end. The organic part of the pore-forming material can be any organic aliphatic and/or aromatic hydrocarbon containing organic linkage groups that can be decomposed at 200xcx9c500xc2x0 C., such as ether containing organic molecule, ester containing organic molecules, amide containing organic molecules, carbonate group containing organic molecules, carbamate group containing organic molecules, anhydride group containing organic molecules, amine group containing organic molecules, enamine group containing organic molecules, imine group containing molecules, azo group containing organic molecules, thio-ether group containing organic molecules, sulfone group containing organic molecules, sulfoxide group containing organic molecules, isocyanate group containing organic molecules, isocyanurate group containing organic molecules, triazine group containing organic molecules, acid group containing organic molecules, epoxy group containing organic molecules, and the like, Organic linkage groups may exist in linear chain and/or cyclic structure. The organic part of the component (b) may contain one functional linkage group or in combination of two or more thereof. The sillane part of the component (b) has at least one functional group to react with the component (a). The preferred functional groups are alkoxy (methoxy, ethoxy, propoxy etc), acyloxy (such as acetoxy), hydroxyl, or halide (such as chlorine).
The cross-linking reaction between the component (a) and the component(b) may take place in the state of the solution or during the state of forming the coating film. In present invention, a component (a) or a mixture of component (a) and (b) can be partially hydrolyzed and condensed in an organic solvent after addition of water and catalyst. When the cross-linking reactions partially take place in the state of the solution to form uniformly distributed copolymer, the component (b) can be added to any state of hydrolysis and condensation of a component (a). The component (b) can be also added to partially hydrolyzed condensate of component (a) before forming the coating film.
Solvents which may be used include any agent or mixture of agents which will dissolve the composition to form a homogeneous liquid mixture of the component (a) and (b). The solvents used for hydrolysis and condensation of the component (a) or a mixture of component (a) and (b) include aliphatic hydrocarbon solvents, such as n-pentane, isopentane, n-hexane, isohexane, cyclohexane and the like; aromatic hydrocarbon solvents, such as benzene, toluene, xylene, alky benzene, naphthalene and the like; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, cyclohexanol, methylcyclohexanol and the like; ether solvents, such as tetrahydrofuran, 2-methyltetrahydrofuran, ethyl ether, n-propyl ether, isopropyl ether, n-butyl ether, diglyme, dioxane, dimethyl dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether and the like; ester solvents, such as ethyl formate, methyl acetate, ethyl lactate, diethyl carbonate, ethylene carbonate, ethylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethylene glycol diacetate and the like; amide solvents, such as N-methyl pyrrolidone, formamide, N-methyl formamide, N,N-dimethyl formamide, N-ethyl formamide, N,N-diethyl formamide, N-methyl acetamide, N-ethyl acetamide and the like. Solvents that have been used in hydrolysis and condensation are completely removed after the reactions to obtain organic silicate polymer as an oil or a powder, which can be dissolved in film-forming solvent and used, or the organic solvent that has been used in hydrolysis and condensation can be directly used for film-forming.
As the catalyst, an acid or a base may be used. Examples of the catalysts used in the present invention include inorganic acids, such as hydrochloric acid, hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid and the like; and organic acids, such as formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, oxalic acid, maleic acid, malonic acid, malic acid, butyric acid, sulfonic acid, phthalic acid, fumaric acid, citric acid, tartaric acid and the like; inorganic bases, such as ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide and the like; and organic base, such as pyridine, piperazine, piperidine, choline, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, monomethyidiethanolamine, dimethylmonoethanolamine and the like. Other catalysts such as metal chelate compounds and salt catalysts can be also used in this invention. The amount of catalyst used in general is 1 mole or less, preferably 0.5 mole or less, per mole of the component (a) or per mole of the sum of component (a) and component (b). The acid and base catalysts may be used individually or in combination.
There are no particular limitations on the reaction temperature when the product is made to have a desired molecular weight. The temperature may preferably be not higher than the boiling point of the organic solvent used, and may preferably be 0xc2x0 C. to 80xc2x0 C. in order to control the molecular weight of the resultant hydrolyzed product. There are no particular limitations on the reaction time at the time of hydrolysis, and the reaction may be completed at the time the product reaches a stated molecular weight. It is usually preferred to set the molecular weight of the partially hydrolyzed condensate product of a component (a) or a mixture of components (a) and (b) within a range of from 500 to 1000,000 as a weight average molecular weight. If the molecular weight of a hydrolyzed condensate of the component (a) or a mixture of components (a) and (b) is less than 500, it may be difficult to form a uniform coating film, and if the molecular weight of a hydrolyzed condensate is greater than 1000,000, condensate polymer may become insoluble. The solid content concentration in the solution, as the sum of the resin component (a) and resin component (b), may suitable be selected from the viewpoint of the desired viscosity of the solution or the film thickness of the coating film, within the range where the solid content dissolves.
In the second step of the process of the present invention, the resin composition containing a mixture of a partially pre-condensed organic silicate component (a) and component (b) or a co-condensate of a mixture of components (a) and (b) is applied to the substrate by methods, followed by heating and drying to evaporate solvent. Here the composition is applied to a substrate by methods known in the art such as spin coating, dip coating, spray coating, flow coating, screen printing or others. The coating method may suitably selected depending on the shape of the substrate to be coated, the required film thickness, etc. When the composition of the present is to be applied to an interlayer dielectric film for a semiconductor device, spin coating method is preferred, since the in-plane distribution of the film thickness will thereby be uniform. The thickness of coating can be controlled by the solid content concentration and the speed of spin. The coatings produced by the method herein are on any substrate such as metals or ceramics but are particularly useful on electronic substrates intended for use in manufacture of a semiconductor component including opto-electronic devices, photovoltaic cells, 3-D devices, silicon-on insulator devices, supperlattice devices and the like.
The last step of the process of the present invention involves heating at a temperature sufficient to effect thermolysis of the organic molecule part of component (b) crosslinked within the matrix of the condensed rigid organic polysilicate. The heating may be conducted as a single-step process or a step-wise process. In the step-wise process the resin composition is first heated to an elevated temperature to effect curing without significant thermolysis. Generally this temperature can be in the range of from about 150 to 350xc2x0 C. Then, the cured composition is further-heated to effect thermolysis of the organic molecule part of component (b). Generally, it is preferred that thermolysis step is performed at a temperature in a range of from 350xc2x0 C. to about 600xc2x0 C., preferably in the range of from 350xc2x0 C. to 500xc2x0 C. Photochemically labile organic molecules can be decomposed by exposure of the composition to suitable radiation to cause photodecomposition. In the single step heating process the curing of the resin composition and thermolysis of the organic molecule part of component (b) are effected simultaneously by heating to a temperature within a range of greater than 350xc2x0 C. up to the lesser of the decomposition temperature of the organic silicate resin.
Any method of heating such as the use of a convention oven, rapid thermal processing, hot plate, or radiant of microwave energy may be used herein. The method used should be capable of rapidly heating the film to the desired temperature. The duration of time that the coating is heated to cure and to decompose will depend on the environment during the heating, the temperature at which it is heated, the rate at which it is heated, and the thickness of the film. At higher cure temperature, and/or higher concentrations of oxygen in the cured environment the cure and decomposition time will be shorter. Generally the coating is heated at cured temperature and decomposition temperature from 1 second to 4 hours. The heating may take place any environment, however preferably an inert environment such as nitrogen, argon, helium or vacuum condition.
The thermolysis of the organic molecule part of component (b) results in the formation of a nanoporous dielectric composition. By the term xe2x80x9cnanoporousxe2x80x9d it is meant that dielectric composition of the present invention median pore diameter less than about 20 nm, preferably has a median pore diameter within a range of about 0.3 nm to 10 nm, more preferably within a range of about 0.3 to 5 nm, more like molecular sized pore. The dielectric composition of the present has a dielectric constant less than 3.3 and preferably less than 3.0, more preferably 2.7 at 25xc2x0 C. The dielectric composition comprises about 5 to 70%, preferably about 5 to 60% by volume of pores, The dielectric composition is optically clear, isotropic structure.

Wherein L is an organic molecule part of the component (b).
The following examples are provided to illustrate the present invention. The detailed preparations fall within the scope of, and serve to exemplify, the more generally described methods set forth above. These examples are presented for illustrative purposes only, and should not used to limit the scope of this invention found in the claims.

Process for preparing insulating material having low dielectric constant

Abstract: The present invention provides a process for preparing a porous wiring interlayer insulating film having very low dielectric constant for a semiconductor device comprising the steps of a) preparing a mixed complex of pore-forming organic molecules and a matrix resin, b) coating the mixed complex on a substrate, and c) heating the mixed complex to remove the organic molecules therefrom, thereby forming pores inside the complex.

Abstract: The porous wiring interlayer insulating film having very low dielectric constant prepared according to the process of the present invention has reduced phase-separation, excellent processibility, isotropic structure and very small pores with a size of a few nanometers or less.


A ride control system and method where the system includes first hydraulics for equalizing pressure between ride control accumulators and boom cylinder head side, and second hydraulics for providing low pressure drop connection between ride control accumulators and boom cylinder head side. When ride control is engaged, the first hydraulics equalizes pressure between ride control accumulators and boom cylinder head side to within a pressure threshold, then the second hydraulics provides the low pressure drop connection between ride control accumulators and boom cylinder head side. Ride control system can include third hydraulics for providing fluid connection between boom cylinder rod side and tank; where after first hydraulics equalizes pressure to within pressure threshold, then third hydraulics provides connection between boom cylinder rod side and tank. The ride control system can also monitor the condition of the ride control accumulators.

Some machines have a ride control system that is hydraulically coupled with other hydraulic systems, for example a loader or boom system. In these and similar machines, it is desirable to have pressure equalization between the ride control system and the coupled hydraulic systems prior to ride control activation. By matching the pressure between the ride control accumulators and the pressure in, for example, the boom cylinders any unintended raising or lowering motion in the boom can be avoided or reduced when ride control is engaged.
It would be desirable to have the ride control system designed to perform one or more of the following functions: (1) to equalize the pressure between the head side of the loader cylinder and the ride control cylinders, (2) to provide a low pressure drop connection between the head side of the loader boom cylinder and the cushioning volume in the ride control accumulators, and (3) to provide a low pressure drop connection between the rod side of the loader boom cylinder and tank. It would also be desirable to have the ride control system perform some auxiliary functions, which could include: (1) to provide a mechanism for dead engine lower, (2) to provide a mechanism for safely discharging the pressure in the ride control accumulators, and (3) to provide condition monitoring of the ride control accumulators.


An electrophotographic photoreceptor containing titanyl phthalocyanine that has a maximum intensity peak of the Bragg angle 2.theta. at 27.3.degree..+-.0.2.degree. with respect to characteristic X-rays of Cu K.alpha. at a wavelength of 1.541.ANG. and which has a maximum intensity peak of 6.8.degree..+-.0.2.degree. in the 2.theta. range of 6.degree.-8.degree. is disclosed.

The present invention relates to an electrophotographic photoreceptor, in particular, one that is suitable for use with printers, copiers, etc. and which shows high sensitivity to light from LED and semiconductor lasers.
Electrophotographic photoreceptors having high sensitivity to visible light are used extensively with copiers, printers, etc. Most common photoreceptors that are used in these applications are inorganic photoreceptors provided with light-sensitive layers that are chiefly composed of inorganic photoconductive materials such as selenium, zinc oxide and cadmium sulfide. However, such inorganic photoreceptors are not completely satisfactory in such characteristics as photosensitivity, heat stability, moisture resistance and durability that are required of electrophotographic photoreceptors to be used with copiers, printers, etc. For instance, selenium will crystallize upon heating or exposure to dirt such as sebum, often leading to deterioration of the photoreceptors that use it as a photoconductor. Photoreceptors that use cadmium sulfide are low in moisture resistance and durability, whereas those using zinc oxide are poor in durability. Further, photoreceptors using selenium or cadmium sulfide are subject to great restraints during manufacture and handling.
With a view to solving these problems with inorganic photoconductive materials, attempts have been made to use a variety of organic photoconductive materials in the light-sensitive layers of photoreceptors and active R&D efforts are being made today along this line. For example, JP-B-50-10496 (the term "JP-B" as used hereinafter means an "examined Japanese patent publication") describes an organic photoreceptor having a light-sensitive layer containing poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone. However, even this photoreceptor is not completely satisfactory in terms of sensitivity and durability. To overcome this problem, an electrophotographic photoreceptor of a functionally separated type has been developed. In this type of photoreceptor, the light-sensitive layer is divided into a carrier generation layer and a carrier transport layer, with a carrier generation material and a carrier transport material being cntained in the respective layers. Since the carrier generating and transporting capabilities are individually fulfilled by different materials, suitable materials can be selected from a broad range of choices and hence a photoreceptor having desired characteristics can be obtained fairly easily. For these reasons, it is anticipated that an organic photoreceptor having high sensitivity and durability can be produced using the concept of function separation.
A great number of materials have so far been proposed that can be effectively used as carrier generating materials in the carrier generation layer of a functionally separated electrophotographic photoreceptor. An illustrative inorganic material that can be used is amorphous selenium (see JP-B-43-16198). A carrier generation layer containing this amorphous selenium is used in combination with a carrier transport layer containing an organic carrier transport material. However, the carrier generation layer comprising amorphous selenium suffers the problem of deterioration of its characteristics because as already mentioned, selenium will crystalize upon heating or exposure to sebum. Organic materials can also be used as carrier generation materials and they are exemplified by organic dyes and pigments. For example, the use of bisazo compounds in light-sensitive layers has been proposed in JP-A-47-37543 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-55-22834, JP-54-79632, JP-A-56-116040, etc. These and other known bisazo compounds show fairly good sensitivity in either the short or medium wavelength range but their sensitivity in the long wavelength range is too low to justify their use with laser printers which employ semiconductor lasers as light sources that are anticipated to insure high reliability.
Gallium-aluminum-arsenic (Ga.Al.As) light-emitting devices which are extensively used in semiconductor lasers operate at wavelengths long than 750 nm. Many studies have so far been conducted in order to obtain electrophotographic photoreceptors that have high sensitivity to light in the wavelength range longer than 750 nm. For instance, it has been proposed that spectral sensitizers that extend the wavelength of sensitivity to the longer range should be added to light-sensitive materials such as Se and CdS having high sensitivity to the visible range. However, as already mentioned, Se and CdS do not have satisfactory resistance to environmental factors such as temperature and moisture and hence are not considered to be ideal materials.
Although many organic photoconductive materials are known, their sensitivity is generally limited, as mentioned above, to the visible region shorter than 700 nm and very few organic materials have satisfactory sensitivity to the range longer than 700 nm. The rare exception is phthalocyanine compounds which are known to have sensitivity to a longer wavelength range than other organic photoconductive materials. An example of such photoconductive phthalocyanine compounds is .alpha.-titanyl phthalocyanine which is described in JP-A-61-239248. This .alpha.-titanyl phthalocyanine has peaks of the Bragg angle at 7.5.degree., 12.3.degree. , 16.3.degree. , 25.3.degree. and 28.7.degree. with respect to X-rays of Cu K.alpha. at 1.541 .ANG.. However, it has low sensitivity and its potential stability during cyclic use is so poor that it will readily experience fogging in electrophotographic processes which rely upon reversal development.
The titanyl phthalocyanine of type II described in JP-A-62-67094 has a peak of the Bragg angle (2.theta.) at 27.3.degree. and the peak of maximum intensity is located at about 7.5.degree. in the 2.theta. range of 6.degree.-8.degree.. However, this titanyl phthalocyanine of type II has low chargeability and suffers from such disadvantages as high levels of dark decay and residual potential.
Thus, the prior art titanyl phthalocyanine compounds of the .alpha.-form and type II have not been completely satisfactory for use in electrophotographic photoreceptors from various aspects such as chargeability, sensitivity and potential stability during cyclic use.


A method is disclosed of producing stable nanosized colloidal suspensions of particles with limited crystallinity loss, products thereof, use of the products and an apparatus for the method. In particular the present invention relates to a wet milling method with small beads wherein the size of the final particles in suspension are stabilized in the nanorange (D50<75 nm) and at the same time the particles substantially maintain the crystallinity.

Dispersion of powders into various solvents is an important discipline for numerous industrial applications ranging from paints to cosmetics. It is well known in nanotechnology that very small nano-materials have properties which significantly differ from their bulk counterpart. For nano particles a large fraction of the particles consist of surface atoms which lead to very high surface area per mass. Suspensions of powders of nano-crystalline materials in solvents, wherein the size of the particle agglomerates in the suspension are in the nano-regime are attracting a lot of attention due to the increased functionality provided. A number of factors determine the functionality of the materials including chemical composition, crystal form and crystallinity, size of crystallites and size of particles in suspension. Examples of size dependent properties are optical transparency, hardness, thermal and electrical conductivity, chemical reactivity and catalytic and electronic properties.
Various techniques have been developed for dispersing powders into different solvents including high shear rate mixing, sonication, milling and/or grinding techniques. One often encountered problem is that such techniques lead to colloidal suspensions, which are hazy and/or milky due to a relatively large particle size in suspension. When applied e.g. as a coating to the surface of a substrate, the haze of the coating fluid is maintained in the coating, which is undesirable in many applications. Further the relatively large size of the particle agglomerates or clusters in such coatings and/or colloidal suspensions may result in a reduced or non-optimal functionality.
Some descriptions of fine grinding by the use of small beads to obtain submicron dispersions are present in e.g. [Dobbs (US 2006/0003013 A1) and Hsu et al (US 2004/0251329 A1)]. Fine grinding is normally carried out in energy intensive grinding mills such as planetary mill, attrition mill, oscillating mill, ball mill, bead mill, and jet mill. These mills deliver huge amount of energy for particle breakage to produce particles below 10 μm. Besides size reduction these energy intensive grinding mills mill also induce structural changes near surface region where the solids come into contact under mechanical forces besides size reduction. The structural changes induces changes in crystallinity, crystallite size and lattice strain. [THILAGAN PALANIANDY 2008].
Although it is possible by fine grinding to obtain submicron dispersion certain application needs crystalline particles. For example the use of TiO2 in photocatalytic applications the activity is directly related to the crystallinity of the TiO2 particles [Jensen et al. 2004] and therefore it is very important to control and maintain the initial crystallinity. The structural changes and the crystallinity loss can't be avoided during fine grinding process as it happens concurrently with the size reduction process [THILAGAN PALANIANDY 2008].
The present invention differs from Dobbs and Hsu et al. as they don't take in to consideration the fact that high intensity milling induces structural changes (e.g. crystallinity loss) concurrently with the size reduction process.
The present inventors have also found that even with excessive processing time of such conventional techniques for producing colloidal suspensions, the particle size may not change further. It has further been found that even at conditions and for formulations, where it is possible to obtain a clear colloidal suspension, a significant loss of crystallinity may result, thereby hampering the functionality of the particles in suspension.
Thus, an objective of the present invention is to mitigate the problems of obtaining a more stable and optically clear colloidal suspension of a nano-crystalline particles in a solvent than in the prior art.
It is further an objective to provide a method, which allows for production of colloidal suspensions of nano-crystalline powders in a solvent, which are faster and/or more efficient and/or result in a smaller particle size in said colloidal suspension and/or maintain a higher crystallinity of said particles in said colloidal suspension and/or have a higher functionality than in the prior art.
One of the objectives of the present invention is to control the crystallinity of the nanoparticles without loosing the stability during the production of nanoparticles suspensions.
Still another objective of the present invention is to provide stable and optically clear colloidal suspension products suitable for making clear coatings with improved functionality.

Production of titania nanoparticle colloidal suspensions with maintained crystallinity by using a bead mill with micrometer sized beads