While a current of a constant current source 503 is equally divided to a plurality of current paths so as to produce a unit current, switches which are series-connected to the respective current paths are controlled by a switch circuit 504 in response to a digital input signal. As a result, since both output currents 505 and 506 whose unit currents are variable can be obtained, a total number of circuit components is reduced, so that not only an occupied area may be reduced, but also resolution in the vicinity of a center may be improved.

1. Field of the Invention
The present invention is related to a D/A converter for outputting an analog signal in correspondence with a digital input signal.
2. Description of the Related Art
Very recently, since fine processing techniques of semiconductor integrated circuits are specifically improved, there is great progress in digital processing techniques for conventional analog processing systems. In digital processing systems, there are many possibilities that input/output signals of such digital processing systems are produced in analog signal forms. Therefore, digital-to-analog (D/A) converters capable of converting digital signals into analog signals are necessarily required in such digital processing systems, the important aspect of which is considerably increased.
Subsequently, a conventional D/A converter will now be explained. FIG. 10 shows a structural diagram of an n-bit D/A converter. Reference numeral 10 indicates an n-bit digital input signal, and reference numeral 11 represents a decode circuit for outputting xe2x80x9ckxe2x80x9d pieces of control signals used to select a predetermined current cell circuit in response to the digital input signal 10. Symbol xe2x80x9ckxe2x80x9d is equal to xe2x80x9c2nxe2x88x921.xe2x80x9d Also, reference numeral 12 indicates xe2x80x9ckxe2x80x9d pieces of current cell selection signals which are outputted from the decode circuit 11, and reference numeral 13 represents xe2x80x9ckxe2x80x9d pieces of current cell circuits which are 25 selected by the current cell selection signal 12 and also own values equal to each other. Reference numeral 14 denotes an output current which is produced by adding such output currents of current cell circuits selected by the current cell selection signal 12 among all of the current cell circuits 13, reference numeral 15 indicates another output current which is produced by adding such output currents of current cell circuits other than the current cell circuits selected by the current cell selection signal 12 among all of the current cell circuits 13. Also, reference numeral 16 shows a current-to-voltage converting circuit for converting the output current 14 into a voltage corresponding thereto, reference numeral 17 denotes a current-to-voltage converting circuit for converting the output current 15 into a voltage corresponding thereto, reference numeral 18 represents an analog output terminal from which the voltage converted by the current-to-voltage converting circuit 16 is outputted, and reference numeral 19 shows an analog output terminal from which the voltage converted by the current-to-voltage converting circuit 17 is outputted.
FIG. 11 is a structural diagram for showing a structure of the current cell circuit 13. Reference numeral 20 shows a current cell selection signal, reference numeral 21 represents a constant current source for supplying a unit current xe2x80x9cixe2x80x9d, reference numeral 22 indicates a current output terminal to which the current xe2x80x9cixe2x80x9d is supplied in the case that the current output terminal is selected by the current cell selection signal 20, and reference numeral 23 indicates a current output terminal to which the current xe2x80x9cixe2x80x9d is supplied in such a case that the current output terminal is not selected by the current cell selection signal 20. Also, reference numeral 24 shows a Pch transistor having a switch function and connected to a current path provided on the side of the current output terminal 22, reference numeral 25 represents another Pch transistor having a switch function and connected to a current path provided on the side of the current output terminal 23, and also reference numeral 26 shows an inverter for inverting the current cell selection signal 20 which is supplied to the gate of the Pch transistor 24.
Next, a description will be made of operations of the current cell circuit of FIG. 11. As indicated in FIG. 11, the current cell selection signal 20 is supplied to the gate of the Pch transistor 25, and also is supplied via the inverter 26 to the gate of the Pch transistor 24 so as to activate the switch function of any one of the current paths of the current cell circuits, so that the output currents derived from the current output terminals 22 and 23 are controlled.
FIG. 12 shows a relationship explanatory diagram for explaining the current cell selection signal 20 (SEL), and values of currents supplied to both the current output terminal 22 and the current output terminal 23. In such a case that the current cell selection signal 20 (SEL)=1, since the Pch transistor 24 (TP1) is turned ON and the Pch transistor 25 (TP2) is turned OFF, the unit current xe2x80x9cixe2x80x9d is supplied only to the current output terminal 22 whereas the unit current xe2x80x9cixe2x80x9d is not supplied to the current output terminal 23. Contrary to the above case, in such a case that the current cell selection signal 20 (SEL)=0, since the Pch transistor 25 (TP2) is turned ON and the Pch transistor 24 (TP1) is turned OFF, the unit current xe2x80x9cixe2x80x9d is supplied only to the current output terminal 23 whereas the unit current xe2x80x9cixe2x80x9d is not supplied to the current output terminal 22.
FIG. 13 is a structural diagram of the current-to-voltage converting circuits 16 and 17. Reference numeral 40 indicates a current input terminal, reference numeral 41 shows an input current having a current value xe2x80x9cIxe2x80x9d, reference numeral 42 indicates a resistive element having a resistance value xe2x80x9cRxe2x80x9d, and reference numeral 43 indicates a voltage output terminal. Next, a description will be made of operations of the current-to-voltage converting circuits 16 and 17. The input current 41 entered from the current input terminal 40 flows entirely via the resistive element 42 to the ground at the zero potential. At this time, such a voltage defined by Ixc3x97R is produced at the voltage output terminal 43 based upon the law of Ohm.
Now, operations of the n-bit D/A converter with employment of the above-explained circuit arrangement shown in FIG. 10 will be described. Assuming now that a total number of the above-explained current cell circuits 13 is xe2x80x9cmxe2x80x9d (symbol xe2x80x9cmxe2x80x9d=0, 1, 2, . . . , k) which are selected in response to the digital input signal 10, the output current 14 becomes xe2x80x9cmxc3x97i,xe2x80x9d and the output current 15 becomes (kxe2x88x92m) X i. As a consequence, in the case that both the current-to-voltage converting circuit 16 and the current-to-voltage converting circuit 17 are arranged by the resistive element having the resistance value xe2x80x9cRxe2x80x9d, such a voltage having a value of xe2x80x9cmxc3x97ixc3x97Rxe2x80x9d is outputted from the analog output terminal 18, and such a voltage having a value of xe2x80x9c(kxe2x88x92m)xc3x97ixc3x97Rxe2x80x9d is outputted from the analog output terminal 19. In this case, since symbol xe2x80x9cmxe2x80x9d may own values from xe2x80x9c0xe2x80x9d to (2nxe2x88x921), it is possible to realize such a D/A converter having (2n) pieces of gradation, namely n-bit resolution in response to the digital input signal.
However, the above-explained conventional D/A converter owns the below-mentioned problems. That is, in the conventional D/A converter having the above-described structure, the unit current is realized by the constant current source. As a result, a plurality of constant current sources are required whose total number is equal to the necessary gradation number. For instance, in the case of a 10-bit D/A converter, 1023 (=210) pieces of such constant current sources are necessarily required. Since the respective constant current sources are made of analog elements, the occupied area of these constant current sources which occupy the silicone wafer within the semiconductor integrated circuit is large. Moreover, in such a case that the resolution is increased by 1 bit, the resultant occupied area becomes approximately two times. Since product cost of a semiconductor integrated circuit largely depends upon an occupied area of this circuit, such a circuit design must be avoided which may induce an increase of the occupied area. In such a technical field of digital mobile communication terminal apparatuses which are known as typical digital processing systems, area-reducing of semiconductor integrated circuits which constitute major circuit components are very important, while terminal apparatuses are gradually made compact and in light weight. Furthermore, when the occupied area on the silicon wafer of the semiconductor integrated circuit is increased, the fluctuations of the respective circuit components on the circuit plane are increased. Otherwise, the wiring line length is made longer. As a result, the adverse influences caused by the impedances of the respective wiring lines are increased, which could deteriorate the precision of the D/A converter.
The present invention has been made to solve the above-explained structural problems, and therefore, has an object to provide such a D/A converter capable of reducing an occupied area of a circuit and at the same time capable of improving resolution by largely reducing a total number of circuit components thereof, as compared with the structure of the conventional D/A converter.
A D/A converter, according to a first aspect of the present invention, is featured by such a D/A converter comprising: a constant current source (constant current source 503); a switch group constituted by switch circuits (switch circuit 504), which is series-connected to the constant current source, and is operated in response to a control signal (current path selection signal 502) to form a plurality of current paths for equally dividing a constant current of the constant current source; decode means (decode circuit 501) for outputting the control signal used to control operations of the switch circuits in response to a digital input signal (digital input signal 500); and current-to-voltage converting means (current/voltage converting circuit 508) for adding currents to each other which are outputted via the current paths of the switch circuits so as to convert the added currents into a voltage.
A D/A converter, according to a second aspect of the present invention, is featured by that in the D/A converter, the constant current is obtained by employing a resistive element (resistive element 511) having one end to which a constant voltage is added instead of the constant current source.
A D/A converter, according to a third aspect of the present invention, is featured by that in the D/A converter, the constant current source is a single constant current source; the switch circuit includes: a plurality of lower-stage switching elements (Pch transistors 73, 74) for forming the plurality of current paths; and an upper-stage switching element (Pch transistor 77) which is series-connected to an upper stage of each of the lower-stage switching elements, and forms a current path for determining a shunt value of the constant currents supplied to the plurality of current paths; and the decode means outputs such a control signal (upper-stage current path selection signal 78, low-stage current path selection signals 71, 72) capable of independently controlling the respective switching elements.
A D/A converter, according to a fourth aspect of the present invention, is featured by that in the D/A converter, a plurality of D/A converters (D/A converter 603) are connected in parallel to each other; and the D/A converter is comprised of decode means (decode circuit 601) for outputting such a signal (D/A converter control signal 602) used to control the respective decode means which constitute the D/A converters in response to a digital input signal (digital input signal 600), respectively.
A D/A converter, according to a fifth aspect of the present invention, is featured by that in the D/A converter, the switch circuit includes: a Pch transistor (Pch transistors 73, 74, 77) for constituting each of the switching elements; and a switch (SW1, SW2, SW3) for selecting a constant voltage (bias voltage 77, 80) by which the Pch transistor is operated in a saturation region and for applying the selected constant voltage to a gate of the Pch transistor when the switching element is selectively turned ON in response to the control signal.
A D/A converter, according to a sixth aspect of the present invention, is featured by that in the D/A converter, the current-to-voltage converting means (current/voltage converting circuit 507, 508) maintains a potential at the output terminal of the switch circuit at a constant value by keeping a potential at the input terminal (current input terminal 90) of the current-to-voltage converting means constant (reference voltage VREF).
A D/A converter, according to a seventh aspect of the present invention, is featured by that in the D/A converter, the decode means selects the switch circuit in response to the digital input signal, and also outputs such a control signal used to supply a unit current to the switch circuit, the unit current being produced by shunting the constant current in correspondence with a total number of the selected switch circuits.
In this invention, the constant current is supplied to the switch circuits, and the constant current is equally distributed to a plurality of current paths of the switch circuits in response to the digital input signal, so that the output current value can be varied. As a result, in the prior art, the current value is increased/decreased in the unit of the constant current, whereas the current value can be increased/decreased based upon such a unit current produced by equally dividing the constant current, and also the resolution can be improved without increasing a total number of the constant current sources. While the resolution may be determined based upon a total number of these current paths, in the case that the constant current is divided into two current paths, the resulting resolution can be increased by 1 bit (namely, two times). Accordingly, when the same resolution as that of the conventional D/A converter is obtained, the necessary occupied area of the D/A converter according to the present invention may be reduced by xc2xd, or less. In other words, when the same occupied area is used, the resultant resolution may be increased more than two times higher than that of the prior art.
In this invention, the constant current of a single constant current source is shunted in correspondence with a total number of the switch circuits which are selected by operating the upper-stage switching elements. Furthermore, the shunted current is subdivided based upon a total number of such current paths which are formed by operating the lower-stage switching elements so as to obtain the unit current. As a consequence, the resolution can be improved without increasing a total number of these constant current sources. In addition, while a total number of the selected switch circuits is changed in response to the digital input signal, the current is variable in response to the quantity of these switch circuits, which is supplied to the current paths which form the unit current. As a result, the resolution in the vicinity of the center can be increased, as compared with that of the conventional structure. Also, since the unit current can be varied, the resolution can be readily changed, whereas the resolution of the conventional D/A converter is changed by controlling the capacity of the constant current source.
In this invention, the current can be equally divided into the respective current paths irrespective of the characteristics of the respective switching elements (transistors).
In this invention, since the potential at the input terminal of the current-to-voltage converting means is kept constant, the potential at the output terminal of the switch circuit can also be kept constant, which is connected to the input terminal. As a consequence, the current which flows through the current paths of the switch circuits can be equally divided in high precision.
In this invention, in particular, such a decode means can be obtained which may allocate the digital input signal to the analog output in such a manner that the quantizing noise in the vicinity of the center can become minimum in response to such an output signal as a sine wave having a large changing ratio in the vicinity of a center of this sine wave.

Matsushita Electric Industrial Co., Ltd.


Light beams emitted from a plurality of light source devices are deflected by a shared light deflector. The light beams are respectively concentrated on different scanning subjects using a first scanning lens and second scanning lenses and are used to perform a scan. All light beams make an angle in a sub-scanning direction to a normal line of a reflecting surface of the light deflector. An incidence surface of the first scanning lens is a surface of which a curvature in the sub-scanning direction changes depending on a main scanning direction. The incidence surface of the first scanning lens is also an optical surface of which a negative refracting power becomes stronger toward a periphery of the surface in the main scanning direction.

1. Field of the Invention
The present invention generally relates to an optical scanning device used in an image forming device, and specifically relates to optical scanning devices that respectively scans different scanning-subject surfaces using a respective optical beam.
2. Description of the Related Art
An optical scanning device, widely known in relation to laser printers and the like, generally has a following configuration. The optical scanning device deflects an optical beam emitted from a light source using a light deflector. The optical scanning device concentrates light onto a scanning-subject surface using an optical scanning and imaging system, such as an fθ (f-theta) lens, and forms a light spot on the scanning-subject surface. The optical scanning device performs an optical scan (main scan) on the scanning-subject surface using the light spot. The scanning-subject surface is a photosensitive surface of a photosensitive medium that is, for example, a photoconductive photoreceptor in an electronic image forming device.
An example of a full-color image forming device is a following electronic image forming device. In the electronic image forming device, four photoreceptors are arrayed in a direction in which a recording paper is carried. A single deflecting unit deflection-scans light beams emitted from a plurality of light source units. The light source units are provided in correspondence with each photoreceptor. A plurality of optical scanning and imaging systems corresponding to each photoreceptor simultaneously perform exposure on each photoreceptor and form latent images. A developing unit visualizes each latent image using developers of differing colors, such as yellow, magenta, cyan, and black. The visualized images are successively superimposed and transferred onto a same sheet of recording paper. Then, the electronic image forming device fixes the transferred images and obtains a color image.
The image forming device using two sets or more of a combination of the optical scanning device and the photoreceptor in this way to obtain a two-color image, a multi-color image, a color image, or the like is known as a tandem-type image forming device. Such tandem-type image forming devices can be configured so that the, photoreceptors share a single light deflector.
FIG. 14A is a perspective view of a configuration of a conventional tandem-type image forming device. FIG. 14B is an enlarged perspective view of a main section of a light source periphery shown in FIG. 14A.
In FIG. 14A, light beams L are emitted from four light sources 101a to 110d and incident on a polygon mirror 102. The polygon mirror 102 is a single light deflector. Each light beam L is concentrated onto four photoreceptor drums 104 as light spots, via an optical system 103. The light spots scan photosensitive surfaces of the photoreceptor drums 104. The photoreceptor drums 104 are scanning-subject surfaces corresponding to each following color: cyan (C), magenta (M), yellow (Y), and black (K). The optical system 103 includes a coupling lens, a cylinder lens, a scanning lens, a reflecting mirror, and the like.
FIG. 14B is an enlarged view of a periphery of the light sources 101a to 101d and the polygon mirror 102 in FIG. 14A. The optical scanning device has an opposed-scanning method configuration in which the light beams L are irradiated onto deflective reflecting surfaces facing the polygon mirror 102.
In Japanese Patent No. 3295281, a following configuration is described. A plurality of light beams that are roughly parallel and separated in a sub-scanning direction are incident on a light deflector. A plurality of scanning optics corresponding to the light beams are arrayed in the sub-scanning direction and perform a scan. In Japanese Patent Application Laid-open No. 2001-4948, Japanese Patent Application Laid-open No. 2001-10107, and Japanese Patent Application Laid-open No. 2001-33720, a following configuration is described. Light beams are incident from one side of a light deflector. An optical scanning system has a three-lens structure. A plurality of light beams moving toward different scanning-subject surfaces pass through scanning lenses L1 and L2. A scanning lens L3 is provided for each scanning-subject surface.
In configurations such as these, in which the light deflector is shared among a plurality of scanning-subject surfaces, the image forming device can be made compact by a reduction in a number of light deflectors.
The number of light deflectors can be reduced in the optical scanning device of a full-color image forming device having, for example, four different scanning-subject surfaces (photoreceptors) corresponding to cyan, magenta, yellow, and black. However, because the light beams moving toward the photoreceptors in the sub-scanning direction are lined in a rough parallel and incident on the light deflector, the polygon mirror forming the light deflector is enlarged in the sub-scanning direction. Generally, among optical elements included in the optical scanning device, the polygon mirror is expensive. The expensiveness of the polygon mirror interferes with a reduction in cost and a reduction in size of the overall device.
In the optical scanning device of the color image forming device, an oblique incidence optical system has recently become known as a means for achieving reduced cost through use of the single light deflector. In the oblique incidence optical system, the light beams are incident on the deflective reflecting surface of the light deflector in the sub-scanning direction at an angle (refer to Japanese Patent Application Laid-open No. 2003-5114).
In the oblique incidence optical system, the light beams are respectively deflected and reflected by the deflective reflecting surface of the light deflector. Then, the light beams are separated by a reflecting mirror or the like and respectively led to corresponding scanning-subject surfaces. In this configuration, an angle of each light beam in the sub-scanning direction (angle at which the light beam is obliquely incident on the light deflector) is set to an angle allowing the reflecting mirror to separate each light beam.
Through the use of the oblique incidence optical system, space between adjacent light beams in the sub-scanning direction allowing the reflecting mirror, to separate each light beam can be secured without an increase in light reflector size (increase in stages and thickness of the polygon mirror in the sub-scanning direction).
However, in an oblique incidence method used in the above-described oblique incidence optical system, image height variations in beam spot diameters increase because of an occurrence of scanning line curvature and deterioration of wavefront aberration.
An amount of scanning line curvature occurrence differs depending on an oblique incidence angle of each light beam in the sub-scanning direction. When latent images written using each light beam are superimposed and visualized using toners of each color, the scanning line curvature appears as color shifts. The light beam is incident on the scanning lens in a twisted state because the light beam is obliquely incident. As a result, the wavefront aberration increases, optical performance, particularly in peripheral image heights, is significantly deteriorated, and the beam spot diameter is widened, thereby interfering with formation of higher-quality images.
In an oblique incidence method, the light beams from the light sources are incident toward a rotation axis of the polygon mirror. Therefore, when the light sources are disposed in positions overlapping with an optical axis of the scanning lens in a main scanning direction, the oblique incidence angle is increased to avoid interference with the scanning lens.
As a method for correcting significant scanning line curvature that is a phenomenon unique to the oblique incidence method, following configurations are proposed. For example, an optical scanning and imaging lens system includes a lens having a lens surface that shifts an inherent tilt of the lens surface within a sub-scanning cross-section in a main scanning direction to correct the scanning line curvature (refer to Japanese Patent Application Laid-open No. H11-14932). Alternatively, an optical scanning and imaging system includes a corrective reflecting surface having a reflecting surface that shifts an inherent tilt of the reflecting surface within the sub-scanning cross-section in the main scanning direction to correct the scanning line curvature (refer to Japanese Patent Application Laid-open No. H11-38348).
In Japanese Patent Application Laid-open No. 2004-70109, a following configuration is described. An obliquely incident light bundle passes off-axis of the scanning lens. Positions of scanning lines are aligned using a surface that changes an amount of aspheric surfaces of child lines of the scanning lens in the sub-scanning direction. In Japanese Patent Application Laid-open No. 2004-70109, an example is given in which the scanning line curvature correction is performed in one scanning lens. In this example, although the scanning line curvature can be corrected, degradation of the beam spot diameter caused by increased wavefront aberration, described hereafter, is not described.
Another problem regarding the oblique incidence method is that significant deterioration of the wavefront aberration easily occurs in peripheral image height (near both ends of the scanning lines) because of skew ray. When such wavefront aberrations occur, spot diameters of the light spots in the peripheral image height become widened. In other words, variations in beam spot diameters among image heights occur. If this problem cannot be solved, high-quality images that have been in strong demand in recent years cannot be achieved. In the optical scanning devices described in Japanese Patent Application Laid-open No. H11-14932, Japanese. Patent Application Laid-open No. H11-38348, and Japanese Patent Application Laid-open No. 2004-70109, significant scanning line curvature unique to the oblique incidence method is successfully corrected. However, the correction of the wavefront aberration is insufficient.
As an optical scanning device that can successfully correct the scanning line curvature and the deterioration of the wavefront aberration that are problematic in the oblique incidence method, as described above, a following optical scanning device is proposed (refer to Japanese Patent No. 3450653). An optical scanning and imaging system includes a plurality of rotating asymmetric lenses. A shape of a mother line connecting vertices of child lines of lens surfaces of the rotating asymmetric lenses is curved in a sub-scanning direction.
However, the lenses having the lens surfaces of which the shape of the mother line connecting the vertices of the child lines is curved in the sub-scanning direction solves the above-described problems by the mother line being curved. As a result, individual scanning lenses corresponding to the incident light beam are required. Therefore, when the lenses are applied to a tandem-type optical scanning system, a number of scanning lenses is increased.
When light beams moving toward different scanning-subject surfaces are incident on a same lens, the above-described problems are solved for one light beam by the shape of the mother line being curved. However, reduction of the scanning line curvature and the wavefront aberration in another light beam becomes difficult.
The curvature of the mother line is in the sub-scanning direction. Therefore, when the light beams incident on the same lens shift in the sub-scanning direction because of influence from an assembly error, a processing error, environmental changes, or the like, a shape of the scanning line curvature changes as a result of influence from a refracting power of the lens in the sub-scanning direction. An initial (or design-stage) color shift control effect on a color image cannot be acquired. As a result, color shifting occurs.
Furthermore, even in the wavefront aberration correction, the changes in a skew state of the light beam are significant on the surface having the curvature because of the incident light beam being blurred. Therefore, stably obtaining a favorable beam spot diameter is difficult.
The scanning line curvature correction is performed in Japanese Patent Application Laid-open No. H11-14932 using the same surface as that in the Japanese Patent No. 3450653. Japanese Patent Application Laid-open No. H11-14932 describes the configuration using the oblique incidence method. However, as described earlier, stably obtaining a favorable beam spot diameter is difficult.
Technological issues of the present invention are to solve the problems of the conventional technology and to:                (1) provide an optical scanning device that can effectively correct the scanning line curvature and the deterioration of the wavefront aberration in an oblique incidence method optical scanning device suitable for achieving low costs, low power consumption, and reduced size; and        (2) provide an image forming device that effectively corrects the scanning line curvature and the deterioration of the wavefront aberration in an oblique incidence method optical scanning device in which color shift occurrence is minimal even during temperature changes.

Optical scanning device and image forming device


A method and apparatus for determining information associated with a particular multicast channel in a multicast network are disclosed. In accordance with the method, a request message requesting information associated with the particular multicast channel is generated and sent to the multicast network. Further, the request message is propagated downstream in a recursive manner via a multicast topology of the multicast network. A response to the request message is propagated upstream via the multicast topology to generate a response message including requested information associated with the particular multicast channel. The information may comprise number of users receiving the particular multicast channel.

1. Field of the Invention
Embodiments of the present invention generally relate to multicast networks. More particularly, embodiments of the present invention relate to method and apparatus for determining information associated with a particular multicast channel in a multicast network.
2. Related Art
Data, voice, and video services have traditionally been delivered to business and residential locations through different mediums (e.g., telephone lines, cable television, broadcast television, data networks, etc.). However, the growth of Internet Protocol (IP) technology now enables the integration and delivery of data, voice, and video through an IP-based network. This integration makes available new revenue generating opportunities to meet the demand from existing customers and new customers for data, voice, and video services through an IP-based network. As the same time, several issues arise in deploying these IP-based networks. In particular, video services provided by IP-based networks pose delivery-type issues and measurement-type issues. The delivery-type issues relate to the manner of delivering the video services while measurement-type issues relate to the manner of tracking or monitoring the number of customers/users receiving the video services.
With respect to delivery-type issues, there are primarily three ways to deliver video services via packets from one node to the other nodes in the IP-based network: unicast, broadcast, and multicast. Unicast delivery requires the source node to address each destination node individually with the destination IP address. If one source node needs to deliver the video services to three destination nodes, for example, the source node has to make three copies of the packets and has to deliver one to each destination node individually. This may be sufficient for low bandwidth video services. However, for delivering typical video services requiring high bandwidth video streams (e.g., multiple megabits per second per stream), it becomes an un-scalable and inefficient solution.
In broadcast delivery, the source node sends one copy of each packet and addresses it to a broadcast IP address. The broadcast IP address is not unique to a destination node. Instead, the broadcast IP address causes the packet to be sent to all downstream nodes within the scope of the broadcast IP address. Each downstream node is required to examine the packets and process them if they are relevant to the downstream node. However, the downstream node disregards the packets if they are not relevant to the downstream node. This may relieve the burden on the source nodes since the source nodes do not have to duplicate the packets for each downstream node. Unfortunately, it leads to a waste of resources at some downstream nodes. That is, if a downstream node does not care about the packets, it still needs to spend resources to examine and discard the packets. The broadcast delivery also wastes network bandwidth as well. In particular, if a node is an intermediate node between the source node and the destination node, the intermediate node needs to forward the packets to its downstream neighbor node, even though its downstream neighbor node may not care about the packet traffic being forwarded to it.
The third delivery method is multicast. Multicast is based on the concept of a multicast group. An arbitrary group of nodes may want to receive a particular packet stream. This group is not limited to any physical or geographical boundaries. A node wanting to receive the particular packet stream being delivered to a multicast group joins the multicast group using a protocol (e.g., the Internet Group Management Protocol (IGMP)). A multicast address specifies a multicast group of nodes that have joined the multicast group and want to receive particular packet stream traffic sent to the multicast group. Another multicast address is utilized for another multicast group having nodes that want to receive different packet stream traffic. That is, each multicast address may be considered to be a separate multicast channel. In multicast delivery, a multicast network is created to control the path that multicast packet traffic takes to deliver the appropriate multicast packets to all nodes of the appropriate multicast group. That is, the multicast network is an IP-based network that utilizes multicast functionality and nodes configured to operate in a multicast network environment to form a multicast distribution tree for appropriately delivering multicast packets to all nodes of the appropriate multicast group. In a multicast network, a source node sends one copy of each packet and addresses it to a multicast address. The multicast network is responsible for forwarding each packet to each node in the multicast group associated with the multicast address.
Since multicast delivery provides efficient use of network bandwidth by delivering packets to the nodes that want to receive them, multicast delivery is the solution for many delivery-type issues raised by offering video services via IP-based networks. Specifically, multicast delivery makes feasible the delivery of broadcast-type video services. A broadcast-type video service refers to video content (e.g., live or recorded programs) delivered on a time schedule to anyone wanting to view the video content, which is analogous to broadcast television or cable television in that the user/viewer tunes to a particular channel to view the video content instead of individually requesting delivery of the video content.
With respect to measurement-type issues, the broadcast-type video service creates the need to track or monitor the number of users receiving particular video content via an IP-based network at any point in time. This information is useful for several reasons. First, the amount of interest in particular video content may be utilized by video content providers in their dealings with advertisers and may be utilized to understand the value placed on the video service by users. Secondly, this information facilitates the efficient allocation of network resources to meet the usage patterns of the video service by users.
Broadcast television and cable television have traditionally relied on several methods to collect viewer information for individual television programs. These traditional methods include placing monitoring devices in selected viewer locations, sending diaries to selected viewers to record television programs viewed, and interviewing by telephone selected viewers about their television viewing patterns. In general, these traditional methods are time-consuming and expensive. Moreover, these traditional methods focus on gathering detailed information from a representative sample of viewers instead of gathering information from all viewers.
While it is possible to use these traditional methods to track or monitor the number of users receiving particular video content via an IP-based network at any point in time, the disadvantages of these traditional methods will not disappear. Moreover, numerous techniques have been developed that utilize the infrastructure of the IP-based network to track or monitor the number of users receiving particular video content via the IP-based network. Unfortunately, these techniques use a significant amount of network bandwidth because they require all nodes of multicast groups to be individually polled by a central monitoring unit or to individually report to the central monitoring unit in a unicast manner, leading to network bandwidth inefficiencies and network traffic bottlenecks. This occurs because even if a node is a member of a multicast group, no user of the video service may actually be receiving the particular video content from the node.

Method and apparatus for determining information associated with a particular multicast channel in a multicast network


A monolithic piezoelectric accelerometer of the longitudinal type having a ass element, a piezoelectric accelerometer sensor element and electrodes interconnecting the mass and sensor elements, in which the mass and sensor elements are formed as a monolithic structure. Included is the method for making the monolithic piezoelectric accelerometer.

Monolithic piezoelectric accelerometers and other piezoelectric accelerometers are known. Examples of such prior art piezoelectric accelerometers are seen in the following U.S. patents:
______________________________________ U.S. Pat. No. Date To ______________________________________ 5,461,918 1995 Mozurkewich 5,193,392 1993 Besson et al. 5,138,414 1992 Shinohara 4,924,131 1990 Nakayama et al. 4,670,092 1987 Motamedi ______________________________________
Accelerometers have a wide range of application, including sound and vibration monitoring, and the detection and measurement of velocity changes. Hence a great many accelerometer sensor types have been devised, developed and made commercially available.
Each type of accelerometer has characteristics which make it more or less suitable for a particular application. For example, geophones are highly sensitive at very low frequencies; hence they are excellent for monitoring earthquakes. Conversely, miniature solid-state accelerometers are very cheap, quick, and easy to use. While they have very poor sensitivity, they fit the needs of sensors for triggering air bags.
The broadest commercial class of accelerometers is the longitudinal type. This type fills the requirements falling between the above extremes. Longitudinal type accelerometers have good sensitivity over a wide frequency band, and are rugged enough for general purpose industrial use. Longitudinal type accelerometers are the key component for most machinery diagnostic equipment, inclinometers, and vibration monitoring. There are many major manufacturers of this type of accelerometer, such as the PCB (registered trademark) piezoelectric accelerometers by Piezotronics Co. and Model 793 Piezoelectric Accelerometer by Wilcoxon Research, of Rockville Md. The scope of the present invention is intended to be limited to this class of piezoelectric accelerometers, the important high-volume commercial type accelerometers.
Further, conventional piezoelectric accelerometers have a mass supported by a piezoelectric element with electrodes At frequencies much below the spring-mass resonance of the system, the seismic mass exerts a stress on the piezoelectric support which is proportional to the acceleration of the system. Under such a stress, the piezoelectric element delivers a charge or voltage to the electrodes which is proportional to the stress. Hence the output charge or voltage is proportional to the acceleration of the system.
For a high quality measurement accelerometer, such a conceptually simple configuration presents some fabrication and operation difficulties. In a typical embodiment, the accelerometer is sealed in a pressure-tight metal container to reduce the effect of environmental pressure variations. This metal container also shields against stray electrical and magnetic fields. To reduce the influence of temperature fluctuations, it may be surrounded by a thermal mass. Alternative arrangements of the mass and piezoelectric elements effects have been devised to reduce interfering effects such as nonlinearities due to high acceleration, and the sensitivity to base strain. Because of the many components involved, the fabrication process can be labor intensive.
For example, one application is in 1-3 composite transducers. Such transducers include a dense array of piezoelectric rods embedded in a soft matrix. The Naval Research Laboratory has a long and continuing interest in the development of accelerometer arrays, particularly for underwater acoustic velocity sensing. Such arrays are formed from commercially available accelerometers.
Commercially available measurement accelerometers are typically constructed in multiple labor-intensive fabrication operations which result in high cost.

The United States of America as represented by the Secretary of the Navy


A method of visually expressing user interface elements on a display is provided which emphasizes those user interface elements which a user would be more interested in and deemphasizes those user interface elements which a user would be less interested in. Certain user interface elements, such as active elements, can be rendered in a sharp manner and be within a depth of field while other elements, such as inactive elements, can be rendered in a blurry manner and outside the depth of field.

As the use of computers in both the workforce and personal life has increased, so has the desire to allow for easier use of them. Many operating systems today utilize a windows based configuration of application programs. Information is displayed on a display screen in what appears to be several sheets of paper.
In existing environments application windows, the desktop and items on the desktop (e.g., icons representing folders, files, applications, etc.) form the core of user interface facilities for the graphical user interface (GUI) of computer systems. While these core facilities can vary in appearance across systems, they have multiple attributes in common. For example, application windows typically have a title bar including window management controls such as a "close" button to dismiss the window, the ability to resize or reposition the window, and the ability to coexist with other windows from the same application or different applications. GUIs which allow for desktop icons also allow such icons to be resized or repositioned. Additionally, the desktop picture or background image for user interfaces can be changed from a default picture or image to another image based on user preferences.
Collectively, the core facilities are presented on screen in a layered manner called a Z-order based on a set of common rules in what is referred to as a "Z-order". For example, the desktop picture or background image is generally presented at the bottom, behind or below other user elements stacked or layered on top the picture or image. The desktop elements remain at the bottom of the stack while the application windows can change their position in a visual stack based on which application window is active and in focus. Thus, when multiple application windows are open on a GUI, the active window is at the top of the Z-order while the remaining windows are inactive and located below the active window in the Z-order. However, in certain instances windows may be rendered side by side such that the user looking at the display may have difficulty in determining which of the windows is active.
In GUIs today, each user interface (UI) element (i.e. text, controls, frames, etc) in the various user interface facilities is rendered in a sharp, crisp manner. Visual techniques to aid in illustrating the layering (Z-order) have included addition of 'drop shadows' (on windows) and the use of different visual representations of active and inactive states. When multiple application windows are open on a GUI, each window, whether active or inactive is rendered in a sharp, crisp manner. In the Windows XP Brand operating System by Microsoft Corporation of Redmond, Wash., when a window is active, the title bar is a bright blue and when a window is inactive the title is pale blue; in both cases the window content is sharp and crisp. In the Mac OS 10 operating system by Apple Computing, Inc. of Cupertino, Calif., when a window is active the title bar is opaque and when a window is inactive the title bar is marginally transparent; in both cases the window content is sharp and crisp. Both Windows XP and Mac OS 10 represent the active and inactive states in a rather subtle manner, which some users may not appreciate, which can lead to difficulty in determining which window is active.
While various visual techniques exist to represent the active and inactive states of UI elements, some users may not readily be able to determine which elements are active and inactive. Accordingly, it would be helpful to provide a further visual indication as to the states of UI elements.

System and method for visually expressing user interface elements


A control unit assembly is disclosed including a housing, at least one processor to control operation of an engine, and a voltage regulator configured to regulate a voltage of at least one rail of the engine. The at least one processing unit and the voltage regulator reside on a common circuit board.

The present invention relates generally to electronic management modules and, more particularly, to those used with internal combustion engines of recreational products.
The electrical operations of an internal combustion engine are, for the most part, controlled by an electronic control unit, hereinafter, an ECU. The ECU includes a wide variety of the electrical controls necessary to operate an engine. These controls can monitor and control various aspects of engine operation including ignition, engine timing, emission systems, air and fuel systems, and temperature sensors, to name but a few.
Depending on engine performance, emission control requires more and more circuitry and/or controls on board such as ECUs. Additionally, advancements in electronic technologies have resulted in increased processing capabilities. As such, ECUs have advanced to control, regulate, and monitor more and more engine systems and properties. However, there remain some engine systems that the ECU is not suited to independently control and regulate, such as high voltage systems requiring voltage regulation.
Modern engines have a variety of needs that can benefit from a high voltage operating environment. While it is possible to provide these higher level voltages, such increased operating voltages cannot always be readily utilized by some engine components and, therefore, regulation and conditioning is required before being delivered to various engine systems. Furthermore, different engine components and systems may have different power consumption requirements and ideal power ranges within which the components and systems operate most efficiently. As such, it is often advantageous to include multiple power or voltage regulators/conditioners such that an ideal power with an ideal voltage is delivered to each of the various engine components and systems.
However, the recreational products industry is one in which size, packaging, and weight are all at the forefront of the design process. As such, having separate devices located at different locations is not just time consuming to install and wire, it reduces available space and increases overall cost. Therefore, having an ECU and various power regulators/conditioners separately mounted and wired throughout the engine is contrary to these objectives.
Additionally, it is ideal that the ECU and the power or voltage regulators/conditioners be disposed within a housing to protect the electrical components from the operating environment. However, the housings, while necessary to protect the components, adds to the size of the ECU and each power or voltage regulator/conditioner. Again, this serves contrary to the objective of minimizing the size, packaging, and weight of the recreational product engine.
It would therefore be desirable to have system whereby the ECU and power or voltage regulator/conditioner requirements of a recreational product are combined. Furthermore, it would be desirable that these requirements be met while minimizing the size, packaging, and weight of the recreational product.

Common composition engine control unit and voltage regulator


In a method for compensation of the first postage value of an unusable printed franking imprint billed in a billing module of a franking arrangement, the occurrence of the unusable franking imprint is detected as a first error event, error information associated with the error event is stored, and information derived from the error information is transmitted to a reimbursement entity for initiation of the reimbursement of the postage value. The error amount information associated with the error event is increased by the postage value and the error amount information is transmitted to the reimbursement entity for initiation of the reimbursement of the postage value.

1. Field of the Invention
The present invention concerns a method for refunding the first postage value of an unusable printed franking imprint that has been deducted in a billing module of a franking arrangement of the type wherein the franking imprint is detected in a detection step and error information associated with the error event is stored and information derived from the error information is transmitted to a reimbursement entity for authorization of the reimbursement of the postage value. The present invention furthermore concerns a franking arrangement suitable for implementation of such a method.
2. Description of the Prior Art
Franking arrangements such as, for example, franking machines, PC frankers or the like typically are used to generate a franking imprint on a mail piece or a label that is attached to a mail piece. This franking imprint serves as verification of payment of the required postage for the carrier of the mail piece. Such franking arrangements normally have a tamper-proof billing module in which a billing (charge) ensues for each franking imprint.
In the billing module, for each franking imprint one or more registers normally are changed by a value corresponding to the postage value to be printed in order to document the consumption (use) of postage by the franking arrangement. In order to prevent fraudulent manipulations, the billing in the billing module normally ensues at or immediately after the point in time at which the print data necessary for the franking imprint were generated. This billing point in time normally occurs a certain time span before the actual printing, i.e. the actual application of the print image on the appertaining medium.
If there is an interference in this time span after the billing and before the printing or during the printing, for example a paper jam or the like, despite the fact that billing has occurred, no franking imprint or no adequately legible (and thus usable) franking imprint is generated. In order to save the user of the franking arrangement the financial loss associated with such a situation, conventionally a series of measures have been proposed.
For example, in European Application 0 814 434 a method is disclosed wherein in such an error situation, data for franking imprints that have already been billed but are currently unusable are stored. For subsequent mail pieces to be franked, it is then checked whether the stored data can be used for the current mail piece. If this is the case, the franking imprint is generated with the stored data for which a billing has already occurred.
An immediate loss is thereby generally prevented for the user. It may be the case, however, that no comparable mail piece is to be franked for a long time, in particular given mail pieces with uncommon dimensions and weights that are seldom franked. Such mail pieces that occur seldomly have the additional disadvantage that they often require relatively high postage values, so a comparably large amount of credit is withheld by the stored data in the case of error. Additionally, such mail pieces are particularly prone to cause errors (such as a letter jam, etc.) due to their unconventional dimensions and weights.
In contrast to this European Application 1 113 401 A1 discloses a method of the general type initially described wherein a compensation request is made in a franking machine for each franking imprint that is detected as billed but is printed such that it is unusable, the compensation request being transmitted to a compensation entity. The compensation entity then checks the compensation request and, if applicable, authorizes (initiates) the compensation. Each compensation request thus includes a series of items of information such as the serial number of the franking machine, the current register state of the franking machine, the account number of the user of the franking machine and the compensation amount.
In a variant of this known method, the registration of the error events ensues offline, i.e. the compensation requests are collected in the franking machine and are transferred to a remote data center upon the next communication of the franking machine with the remote data center. The data center then processes the compensation requests and initiates the appropriate reimbursement.
With this known method it can be prevented that unusable credit is restricted in the franking machine over a longer time span. This known method, however, exhibits the disadvantage that the compensation request represents a relative large amount of data, such that on the one hand a comparably large amount of storage space is required for the individual compensation requirements (depending on the frequency of the errors). A relatively high storage capacity thus must be kept available for the compensation requirements, thereby increasing the production expenditure for the franking machine. Furthermore, a relatively large amount of data may possibly have to be transferred to the data center, such that the franking machine has to be operated for a relatively long period of time for this procedure or with an increased demand on the communication device. Lastly, a relatively long time span is necessary for sequentially processing the compensation requirements, whereby the otherwise-available processing capacities of the data center are limited.

Method and arrangement for compensating a postage machine user for printed and billed, but unusable franking imprints


A lamp ballast includes an inverter circuit, a resonant circuit, a control circuit, and a startup circuit. When the DC bus reaches its final value, a capacitor in the startup circuit charges to a predetermined voltage, at which point a pulse is sent to start a gate drive circuit in the inverter. Additionally, a gate in the control circuit is initially OFF, allowing full power to the lamp, and a capacitor in the control circuit charges to a predetermined voltage, at which point a gate is turned ON. When the gate is ON, power to the lamp is reduced. The control circuit capacitor is selected so that it charges for a sufficient period to allow the lamp to complete a glow phase of startup before turning on the gate and reducing power as the lamp transitions into an arc phase.

The present application is directed to electronic ballasts. It finds particular application in conjunction with the fluorescent lamps and will be described with the particular reference thereto.
A ballast is an electrical device which is used to provide power to a load, such as an electrical lamp, and to regulate the current provided to the load. The ballast provides high voltage to start a lamp by ionizing sufficient plasma (vapor) for the arc to be sustained and to grow. Once the arc is established, the ballast allows the lamp to continue to operate by providing proper controlled current flow to the lamp.
Typically, after the alternating current (AC) voltage from the power source is rectified and appropriately conditioned, the inverter converts the DC voltage to AC. The inverter typically includes a pair of serially connected switches, such as MOSFETs which are controlled by the drive gate control circuitry to be "ON" or "OFF."
In conventional voltage fed designs, the inverter does not boost the power applied to the lamps during the glow-arc transition, causing this transition to be slower than desired. Additionally, different sizes and/or lengths of lamps translate into different current requirements, which in turn require conventional inverters to limit the amount of power provided to the lamp terminals.
The following contemplates new methods and apparatuses that overcome the above referenced problems and others.

Starting fluorescent lamps with a voltage fed inverter


Approaches for natural language processing include a multi-layer encoder for encoding words from a context and words from a question in parallel, a multi-layer decoder for decoding the encoded context and the encoded question, a pointer generator for generating distributions over the words from the context, the words from the question, and words in a vocabulary based on an output from the decoder, and a switch. The switch generates a weighting of the distributions over the words from the context, the words from the question, and the words in the vocabulary, generates a composite distribution based on the weighting of the distribution over the first words from the context, the distribution over the second words from the question, and the distribution over the words in the vocabulary, and selects words for inclusion in an answer using the composite distribution.

Natural language processing and the ability of a system to answer natural language questions about the content of a natural language sample is a benchmark to test for context-specific reasoning about information provided in natural language form. This can be a complex task because there are many different types of natural language questions that can be asked and whose answering may require different types of reasoning and/or different types of analysis.
Accordingly, it would be advantageous to have unified systems and methods for simultaneously being able to answer different kinds of natural language questions.
In the figures, elements having the same designations have the same or similar functions.

Multitask learning as question answering


The present invention is a minimally invasive surgical method for fusing adjacent vertebrae. A first K-wire is inserted into the spinous process of an upper vertebrae. A second K-wire is inserted into a transverse process of a lower vertebrae. A first fixation block is secured to the first K-wire and a second fixation block is secured to the second K-wire. A rod member extends across the K-wires. A swivel block assembly is secured to achieve a desired angle for a first axis along which a first screw will be implanted into a facet joint. The swivel block assembly is secured at a desired axial position on the rod member. Percutaneous access to the upper vertebrae along the first axis is then obtained via a cannula. A removable screw having a threaded section for implantation across the facet joint and an elongated shank section that is shearable subcutaneously is inserted through the cannula. The threaded section is implanted along the first axis across the facet joint to attach the upper and lower vertebrae. A shearing tool is inserted percutaneously over the shank section and the shank section is sheared off immediately above the lamina.

Over 200,000 spinal fixation and spinal fusion procedures are performed annually to correct various congenital and degenerative spinal disorders in humans. Many of these corrective surgical procedures are performed in the lumbar and lumbosacral regions of the spine where traumatic and age-related disc degeneration is common. One such procedure involves the implantation of spinal fixation instrumentation, including plates and rods, using pedicle screws. Another procedure involves the implantation of one or more anterior fusion cages into the intervertebral disc space following a discectomy. These and other known spinal fixation and/or fusion procedures can be quite invasive, traumatic, and time consuming. Further, problems with post-operative stability and pseudoarthrosis are often associated with many of these procedures.
It is well known that the two facet joints, which are formed between each pair of adjacent vertebrae, share and support the axial load on the spine with a respective intervertebral disc. Accordingly, it has been suggested to place screws either directly across the facet joints of adjacent vertebrae or indirectly across the facet joints through the lamina (i.e. translaminar) as both a primary means for spinal fixation and as a secondary means for fixation to augment anterior fusion or pedicle screw fixation instrumentation. Indeed, this suggestion has been accepted by many surgeons as facet screws (direct and translaminar) are now being implanted on a regular basis. In order to further improve upon the use of such facet screws, a minimally invasive method and apparatus for accurately and repeatably placing facet screws across the facet joints and fusing adjacent vertebrae is needed.

Minimally invasive method and apparatus for fusing adjacent vertebrae


A system and method for mounting a telescopic sight or “scope” to a firearm. The system is convertible or universal, in that it includes interchangeable mounting plate inserts allowing the mounting plate to be installed onto two or more different types of firearms having differing mounting hole configurations.

Target shooters, hunters, and other users of firearms often mount telescopic gun sights or "scopes" to a firearm for improved accuracy. Typically, the barrel and/or receiver portion of a firearm, such as for example a muzzle-loading or breach-loading firearm, is drilled and tapped with a plurality of mounting holes for optional attachment of a mounting plate or base. Scope mounting rings engage the scope and are clamped to the mounting plate to securely affix the scope to the firearm.
Different manufacturers and/or models of firearms, however, commonly utilize different configurations of mounting holes. For example, firearm Manufacturer A may drill and tap its receivers for one type of threaded fasteners spaced a lesser distance apart, whereas firearm Manufacturer B drills its receivers for another type of threaded fasteners at a greater distance apart. As a result, a different mounting plate must be utilized to mount a scope to Manufacturer A's firearms than is used to mount a scope to Manufacturer B's firearms. This requires retailers to stock multiple mounting hardware types, increasing inventory costs and space requirements. And consumers shopping for scope mounting hardware are forced to study the various hardware to determine which is appropriate for mounting a scope to their particular firearm, which is time-consuming, inconvenient, and sometimes leads to incorrect purchases that must be returned and exchanged. Also, if a user wishes to remove a scope from one firearm and remount it onto another firearm, new mounting hardware is often required.
Thus it can be seen that needs exist for improved mounting hardware for attachment of a scope to a firearm, which eliminates the need for particularized components for different variations of mounting hole configurations. It is to the provision of a universal scope mount meeting this and other needs that the present invention is primarily directed.


The invention relates to a method for inspection of periodic structures on lithography masks using a microscope with adjustable illumination and an operating element for movement of a mechanical stage with the lithography mask attached to it in order to record images of the lithography mask at a computer-controlled location on the lithography mask. The position, the size and the pitch specification of the lithography mask are stored.

As is known in microlithography, semiconductor structures are produced by the imaging of a structure which has previously been produced on a lithography mask on a wafer that is coated with a photoresist and by exposure and subsequent development of the photoresist.
After the manufacture of the lithography mask, the mask has different properties, which vary from mask to mask. These different properties have a considerable influence on photolithography and on the imaging thereof. In this case, a distinction is drawn between general (global) and local properties which are normally specified.
Global properties are, for example, the error in the line width (CD target value) from the target size (offset error), as well as the fluctuation in the error over the image area (uniformity error). In alternating phase masks, there are structures which have phase-shifting properties when illuminated with coherent light. These phase shifts are produced by etching the relevant structures into the glass. Undesirable brightness errors occur due to discrepancies from the ideal etching depth, and these likewise represent a global mask property.
Local properties are defects on the mask which occur either due to faults in the production of the mask or due to subsequent impurities, e.g., dust.
The aim when producing lithography masks is to produce a lithography mask that satisfies a number of requirements. With respect to the local properties, currently the masks are tested by process inspection and quality measurements.
At present, systematic manufacturing faults in lithography masks such as regular errors in the line separation (offset target error) and changes in the line width (uniformity error) are measured directly on the structures by means of different SEM measurements (Scanning Electron Microscopy) at a large number of points on the mask. However, this is a time-consuming and unreliable assessment process, since the measurement errors and the poor reproducibility of SEM measurements are disadvantageous. For example, the direction of an electron beam significantly influences the measurement result. For this reason, this method is not suitable for lithography masks which are etched in quartz, since there are no well-defined etchings for SEM measurement in masks such as these.
Mask assessment for new mask technologies, such as interference masks, is very difficult. Interference masks contain trenches which have been etched in the mask and which produce diffraction (phase shifting) of the light that is passed through. However, no known method exists for determination of the diffraction and transmission parameters.
A combination of a depth measurement and of an optical measurement using an MSM microscope (Microlithography Simulation Microscope) is used. The measurement values which are obtained with a microscope such as this are compared with line width measurements of structured wafers in order to obtain information about the value of the newly produced lithography masks.
A further aim is to make improvements in defects inspection. Since some defects on the lithography mask are transferred to the chips formed on the wafer, it is very important to ensure an error-free mask structure. Since each process step during mask manufacture unavoidably generates some defects in the lithography mask, it is necessary to be able to inspect and to repair lithography masks.
During mask inspection, the lithography mask is examined for defects, and the defects which are found are classified on the basis of their importance for the lithography and their influence on the functionality of the chip. Mask defects which endanger the functionality and the reliability of the chip function must necessarily be repaired.
The test devices which are currently used employ laser scanning microscopy in order to check lithography masks for defects. In this case, the mask surface is scanned with a laser beam, and the reflected and transmitted light is measured. In defect-free areas, the sum of the reflected light and of the transmitted light is greater than a predefined value. In contrast, in the event of defects, the light is scattered, so that the sum of the intensities is less than the predefined value.
In the case of high-end masks, this approximation is extended in various ways, for example by using an adjacent chip as a reference for the "die-to-die" inspection rather than comparison with a constant reference signal ("die-to-database").
For standard quality masks, this approximation is simple and efficient in terms of the inspection time and the costs. For high-end masks and in particular for interference masks, this approximation suffers from the fact that masks such as these use a different, shorter wavelength for the first lithography step than that used for the final lithography step. However, since a shorter wavelength means poorer resolution, the sensitivity with respect to defects is also less than during the final lithography process.
Another problem with the laser scanning method is that the interference masks (diffraction gratings) are seen very differently during laser scanning and during optical imaging.
One solution to this problem is to simulate the lithographic process by means of a modified microscope. Lithography microscopes of this type are referred to by the product name MSM (Microlithography Simulation Microscope) and are offered, for example, by the company ZEISS. MSM has the advantage of using the same wavelength as that used for the lithography process, the same illumination of the lithography mask, and the same optical presets for the aperture angle of the projection optics.
In contrast to lithographic exposure, in which the image of the lithography mask is reduced in size, MSM magnifies the image of the lithography mask onto a sensor. However, MSM can image only a small section of the mask at one time.
If the lithography mask is scanned step-by-step, it is possible to record images of it which essentially correspond to the intensity with which a wafer would be exposed.
If a fault has a severe influence on the exposure of the resist, this would be evident from the air image which has been recorded by the MSM. However, in order to make it possible to use the microscope for inspection, an error signal is required which signals the defect. The lithography mask must therefore have various identical chip layouts so that the microscope can compare these images in pairs.
The disadvantage of this method is that each image is influenced by general noise, and that the final error image is subject to greater noise.
Another disadvantage of this method is its complexity, since the entire image of a die must be scanned into the memory of the computer, must be adjusted, and must be compared. This necessitates considerable memory volume as well as considerable computation time.
Upon insertion into a mask stage, an image is generally rotated slightly with respect to the sensor. This mask method can determine and correct the rotation of the mask and the magnification factor of the mask with high accuracy. If the magnification and image rotation are known, the Fourier coefficients can be determined. A reconstructed, noise-free image is obtained by back-transformation by means of a Fourier series.

Method for inspection of periodic grating structures on lithography masks


An illustrative behavior analysis system and a corresponding method are designed to analyze telecommunications-event records and other relevant records associated with wireless terminals to infer whether a wireless user's pattern of behavior is substantially similar or even identical to the pattern of behavior of another user, possibly a known actor. A pattern of behavior typically comprises call-related and location attributes over a period of time. Accordingly, the illustrative embodiment infers an identity or a substantial similarity as between two seemingly distinct users of wireless terminals, based on: (i) how precisely a candidate's pattern of behavior matches a pre-defined pattern of behavior, and/or (ii) how precisely a candidate's pattern of behavior matches another candidate's pattern of behavior.

FIG. 1 depicts a diagram of the salient components of wireless telecommunications network 100 in accordance with the prior art. Wireless telecommunications network 100 comprises: wireless terminals 101 and 110, cellular base stations 102-1, 102-2, and 102-3, Wi-Fi base stations 103-1 and 103-2, wireless switching center 111, and location system 112. Wireless telecommunications network 100 provides wireless telecommunications service to all wireless terminals within its coverage area, in well-known fashion. Global Positioning System ("GPS") constellation 121 is also depicted in FIG. 1, but is not part of wireless network 100.
Data that is generated by wireless network 100 can provide clues to an investigator. For example, a known suspect's calling records can be obtained to determine what telephone and/or data communications that suspect has engaged in. Network-supplied calling records are well known in the art, and typically comprise one or more of:                an International Mobile Subscriber Identity ("IMSI") number that is assigned to the wireless terminal of the subscriber, or to a removable and swappable subscriber identification module ("SIM") card that is receivable in the wireless terminal,        the telephone number assigned to the subscriber's account,        the origination time of the call,        the ending time of the call,        the origination time of a text (e.g., SMS) message,        the receiving time of a text (e.g., SMS) message, and        cell ID or enhanced cell ID location information (as is well known in the art) relative to the respective times,These records are often referred to as "call-detail records" or "CDRs."
Identifying potential suspects according to telephone calling records and CDRs is well known in the art, but is a limited domain. To avoid detection or surveillance, people can use disposable or pre-paid wireless terminals that cannot be traced back to a named individual. For example, a user might use wireless terminal 101 for a period of time, then deactivate it or discard it and begin using wireless terminal 110. Likewise, SIM cards can be swapped and exchanged, thus changing the wireless identity of the wireless terminal with each successive SIM card. For example, a user might discard a first SIM card for wireless terminal 101 and replace it with a second SIM card for the same wireless terminal, thus changing the terminal's wireless identity within the wireless network. Of course, there are many innocent explanations too, such as a parent passing a wireless terminal to a child, or an entire family using a single pre-paid terminal, or a couple accidentally swapping look-alike terminals—all quite apart from trying to evade detection. In all these scenarios with disposable and pre-paid configurations, an investigator may be unable to put a name to a number.
Moreover, when investigating a crime, a terrorist attack, a missing persons case, a threat, and like situations, the cost of a false positive is high. A falsely identified suspect can be irreparably harmed by a false positive. Conversely, the true suspect or perpetrator remains at large. Therefore, investigators who face long lists of candidate suspects—especially candidate suspects whose identity is unknown—would benefit from automated took that can help minimize the incidence of false positives. Therefore, an approach that reduces the risk of fake positives would be useful and desirable.

Recognizing unknown actors based on wireless behavior


A soft-sided tote bag is convertible between expanded and retracted states by selective operation of a zipper. The interior of the bag is enclosed in both states by two pairs of end flaps.

1. Field of the Invention
This invention generally relates to a bag convertible between expanded and retracted states and, more particularly, to a soft-sided bag whose interior is enclosed to protect accessories in both states.
2. Description of Related Art
It is well known to carry accessories such as camera equipment, computer equipment and the like in a soft-sided tote bag. Although generally satisfactory for its intended purpose, more carrying space within the bag is often needed to handle additional unexpected accessories. To provide such additional space, the art has proposed adding multiple compartments at the exterior of the bag. Yet, the need persists for more carrying space, and especially for protecting the accessories within the bag from rain, dust and like contaminants entering the bag, from falling out of the bag, and from impacts encountered during handling.


A valve is constructed to strike a balance between providing relatively high sealing yet low friction as components of the valve move. The valve includes a port and an actuator movable relative to the port. A member is disposed between the port and the actuator. The actuator acts on the member so that it can intermittently seal the port as it moves. The member and the actuator have a substantially low friction interface, whereas the seal member and the port have a substantially high sealing interface. The valve can be used in an engine, such as a rotary valve in an internal combustion engine.

1. Field of Invention
The invention relates to valves and more particularly to rotary valves.
2. Discussion of Related Art
Valves are used to control the flow of fluids, such as air or water, or solids, such as powders, and typically include a seal component that covers a flow port through the valve. To provide an adequate seal, valve designers strive to create a relatively tight fit or seal between the seal component and the port, and this may be accomplished with relatively large biasing forces acting on the seal component. However, such a high biasing force must be overcome when it is desired to actuate the valve, resulting in a relatively high energy cost.
Many common valve applications, such as poppet valves used in internal combustion engines, could benefit from a reduction in efficiency losses. Efforts have been made to employ rotary valves in engines, which require less energy to actuate than poppet valves and offer additional advantages, such as allowing the engine to operate at a higher rpm, allowing for the use of variable valve timing, and providing fewer parts. However, these rotary valves have not gained widespread use, in part because the operating efficiency gain over conventional poppet valves is not significant, thermal expansion is difficult to manage, cost is relatively high, and acceptance by automotive engine designers has been low. Improvements to valves and rotary valves in particular have largely focused on material selection that only slightly reduced these deficiencies including frictional losses while maintaining or improving the sealing characteristics.


A base station (21, 22, 23) in a radio communication system (20) comprises a channel allocator (62) for allocating communication channels in accordance with a fully distributed dynamic channel allocation method. The channel allocator accesses a Preferred Channel List (PCL) (64) to allocate the communication channels. The PCL ranks channels (116) in accordance with the occurrence of prior events on the channels (112), such as interrupted calls (122), blocked call setup requests (118), and calls successfully completed (106) and in regards to the mean quality margin (110) and the current channel quality (114). The channel allocator (62) allocates (140) the first available channel (128) in the PCL having a free timeslot (132) and with good current channel quality (136). Alternatively, the channel allocator (62) allocates communication channels in accordance with an optimal dynamic channel allocation method. A list of channels assigned to the base station is updated by removing channels (372) that are locally heavy loaded (366) and in poor quality (370) and by adding channels (390) if the channels are locally heavy loaded (384), and in good quality (394) for a period of time (392). Unassigned channels may be borrowed (388) if they are in good quality (382), are in a locally lightly loaded period (384), and have been idle for a predetermined period of time (386). The assigned channels of the base station (340) are allocated first (356, 360), with the borrowed channels being allocated (350) when no assigned channels are available (340).

Radio communications involves either one-way (e.g. selective call signalling or paging systems) or two-way communications (cellular, cordless telephone, or digital personal communication systems) over radio waves. Communication takes place on channels, comprising time division multiplexed (TDM) timeslots or frequency division multiplexed (FDM) frequencies, or a combination thereof.
For various radio communications, fixed radio frequency spectrum are assigned. For example, in the United States, the Federal Communications Commission reserves various portions of the radio frequency spectrum to designated communication services. The radio frequency use is therefore limited to assigned services. The radio frequency use is more overtaxed within certain areas where the number of frequencies allocatable for communicating between radio transceivers in a system are severely limited.
As communication between radio transceivers is initiated, the system allocates a channel or channels for communication service therebetween. With the increase in radio communications, such as cellular and cordless telephone usage, the method for allocating channels must allocate channels utilizing the assigned frequencies in a manner to accommodate ever increasing concurrent users. Signal interference may result from multiple simultaneous usage of the same channel in neighboring geographical areas (co-channel interference) or usage of adjacent channels in the same geographical areas. The resulting interference reduces the level of system service quality. It is therefore a primary concern of the system operator to allocate channels for communication in a manner to allow the greatest efficiency of usage while reducing interference in order to maintain a certain level of service quality.
There are generally two types of channel allocation methods: fixed channel allocation and dynamic channel allocation. Fixed channel allocation methods fix the channel assignments during the entire course of operation. Since the channels are allocated only once, the fixed channel allocation method can be very time intensive and, therefore, have a good chance to provide a high level of channel reuse for any given conditions. Fixed channel allocation methods are simple and may approach being optimal in terms of channel reuse to any given traffic pattern for a given system. But the fixed channel allocation is not adaptive to a changing service environment. Also, to add or remove a base station from the system is cumbersome and fixed channel allocation methods are unable to automatically initialize the channel allocation.
Dynamic channel allocation methods, on the other hand, allocate channels in accordance with a method which is adaptive to traffic and environment changes. Since dynamic channel allocation methods do not assign channels, channels can be used in any area as needed. In addition, most dynamic channel allocation methods can initialize automatically. Unfortunately most of the existing dynamic channel allocation methods are too dynamic to have good performance in terms of channel reuse.
Generally, dynamic channel allocation methods have better performance than fixed channel allocation methods in light and unevenly distributed traffic. However in heavy traffic, typical dynamic channel allocation methods perform worse than fixed channel allocation methods.
Thus, what is needed is a method and apparatus for channel allocation which combines the benefits of fixed channel allocation methods and dynamic channel allocation methods that is adaptive to the slowly changing environment while approaching the maximum system capacity with acceptable service quality for any environment.

Method and apparatus for dynamic channel allocation


A transport tank for use in live haul truck transport of aquatic species such as catfish is formed of rotomolded plastic. The tank has a grooved floor which is covered with a perforated plate. The grooves contain aeration lines which run along the length of the floor. The aeration lines have threaded end fittings which engage a doubly threaded nut which is received in a sidewall opening of the tank. The hoses can be removed for servicing by simply unthreading the doubly threaded nut and pulling the aeration lines out of the sidewall openings.

1. Field of the Invention
The present invention relates generally to a device and method for transporting live finned fish, and more specifically to an improved truck mounted transport tank for transporting live catfish. While a primary market for the invention is live catfish transport, it can also easily be adapted for the transport of other aquatic species such as crabs, oysters, lobsters, shrimp, and the like.
2. Description of the Prior Art
As will be familiar to those skilled in the relevant industry, live fish in the United States have traditionally been transported over-the-road by "live haul" trucks. These are typically flatbed trucks that have been significantly modified to carry fish. Typical modifications include the permanent installation of one or more insulated fixed tanks or boxes in the flatbed. These tanks typically have hinged lids on the top and one or more circular or rectangular release gates on side of the tanks for simultaneously discharging water and fish. The earlier mechanical aerators using small motors and propellers have more recently given way to liquid oxygen tanks, manifolds carrying the gaseous oxygen to oxygen flow meters, and subsequently to aeration bubblers located in the bottoms of the tanks.
The standard live haul truck may be used for live bait hauling or fingerling stocking as well as for transporting live food fish. Due to the variety and types of loads, pickup and discharge locations, the configuration of these live haul trucks is far from standardized. Rather, the live haul truck is often a highly specialized, dedicated piece of equipment which is not intended for alternative uses. In ordinary practice, the fish are loaded dry (i.e., in nets without water), directly from the tanks and/or ponds of the fish farm into the integral fish tanks of the live haul truck.
Traditional live haul trucks which are commercially available in the industry include such companies as Seaplast PLC (Dalvik, Iceland), Seaplast Canada Ltd. (New Brunswick, Canada) and Peterson Fiberglass Laminates, Inc (Shell Lake, Wis.). These insulated tanks may be manufactured from a number of different materials including fiberglass, plastic, wood, and metal.
Just as in the case of fixed culture environments, such as containment ponds, tanks and aquariums, the transport tanks used on live haul trucks typically need an aeration system to supply sufficient oxygen to the aquatic livestock. Without an aeration apparatus in the aquatic environment, the livestock may die due to lack of oxygen. In addition to supplying oxygen, the aeration apparatus typically provides the additional advantage of achieving agitation of the bottom layers of the water to help prevent stagnation of the bottom portion of the aquatic environment. Agitation of the bottom of the aquatic environment also stirs up and redistributes the nutrients or food that have sunk to the bottom. The aquatic environment also requires a controlled circulation to prevent stagnant corners or regions.
One problem that exists at the present time is that the prior art tanks have tended to place the aeration lines on the bottom floor of the tank interior. The fins of the fish often damage the aeration lines, presenting a maintenance problem. In the case of routine maintenance, or an emergency situation, it was generally necessary to remove the fish and drain the tank in order to allow a worker to climb down into the interior of the tank to access the lines. In this regard, there is an obvious need to limit the handling, netting, moving by pump, draining via chutes, and otherwise touching of the live fish that would be required during such maintenance operations. Any time the fish are handled and moved, there is the chance of injury. Even careful handling of the fish can result in fungus and other type skin infections which are injurious to the fish.
Various aeration systems have been used in truck transport and other type systems in the past. For example, U.S. Pat. No. 6,557,492, shows a live fish transport system in the form of insulated tanks which can be used with live haul trucks. The tanks are made of polyethylene and may include "fork liftable" footed bases. As explained beginning at Col. 11, line 1, et seq., anchors 275 are adhered to the interior surface of the tank which serve as brackets for mounting the oxygen diffusers in position.
U.S. Pat. No. 3,401,671 shows a fish shipping container formed of an insulating material such as Styrofoam™. The bottom wall is provided with a grid 18 made up of lands 20 and channels 22. The channels provide air circulation to prevent conduction of heat from the container to floor of the freight compartment but are not used to house aeration conduits.
U.S. Pat. No. 5,606,935, shows a transportable fish tank including a mounting frame or base 120 and longitudinal base frame members 121. In one aspect of the disclosure, longitudinal recesses 48 are provided for inlet conduits, suction conduits and skimmer conduits (Col. 8, lines 12–14). These conduits are indicated as "I", "SU", and "SK" in FIGS. 2, 9 and 10. These exterior conduits are apparently connected to such devices as the skimmer assembly (65 in FIG. 6). The lower tube 67 passes upwardly through the tank wall and may be sealed with a sealing ring or gasket.
None of these prior art systems address the problem of making the aeration lines easily accessible from the tank exterior for routine maintenance type operations.
Therefore, there remains a need for an apparatus that adequately aerates the tank of a long haul truck which is easy to access for maintenance purposes.
There is also a need for such a device having an aeration apparatus which is located in a protected fashion relative to the live fish in the tank, so that the fins of the fish do not come into contact with the aeration lines themselves.
There is also a need for an improved method for maintaining oxygenation, providing bottom agitation and controlling circulation to an environment for aquatic livestock, such as a catfish transport truck.


An apparatus and method for performing an incision in, for example, the wall of the eye, including a suction cup which may be fixed to the wall of the eye, a cutting tool the cutting edge of which is in the shape of a closed curve, in particular a circle, surrounding tightly the rim of the suction cup, and capable of moving along the rim of the suction cup in order to penetrate into the wall of the eye and to incise it along the closed curve, means to create suction in the central zone of the suction cup in order to fix it firmly to the wall of the eye, and means to move the cutting tool along the rim of the suction cup, and to have it penetrate into the wall, at a depth at least equal to the thickness of the wall.

The subject matter of this invention is concerned with apparatus for performing an incision in the inner wall of the capsule for the removal of the crystalline lens of the eye during cataract surgery and the like, the art being replete with conventional techniques for achieving such ends.
While applicable, also, to other surgical and related applications, the invention is concerned more specifically with insuring immobilization of the surface to be incised, such as the wall of the eye, while the incision is made, and to the further insuring of the accuracy and control of the position of the line(s) of cut and the cleanness of such cut --features not heretofore totally satisfactorily addressed by prior surgical procedures.
In the important illustrative application to cataract surgery, where the apparatus serves the purpose of a so-called microcystotome, these results are admirably achieved, according to the invention, by a device that includes: (a) a suction cup which can be fixed on the wall of the crystalline lens; (b) a cutting tool with cutting edge or cutting path having the shape of a closed curve, in particular a circle, which surrounds tightly the rim of the suction cup and which can be moved along the rim of the suction cup in order to penetrate into the wall of the eye and to incise it along this closed curve (c) means to create suction in the central zone of the suction cup in order to fix it firmly on the wall of the eye; and (d) means to move the cutting tool along the rim of the suction cup in order to have it penetrate into the wall of the eye to a depth at least equal to the thickness of this wall.
It is through this technique, that the cutting tool can penetrate perpendicularly into the wall surface in the immediate proximity of the rim of the suction cup, which serves admirably to immobilize this wall, thus ensuring a very clean cut.

Method of and apparatus for performing surgical incisions