The present disclosure provides a system, apparatus and method to reduce phase noise associated with a received data signal, while optimizing system performance. An optimal length of a digital filter, employed in a carrier phase recovery process, is determined such that phase noise is reduced in the received data signal. Reduction of the phase noise present in the received data signal leads to improved receiver performance. The optimal length of the digital filter may be continuously performed, resulting in optimal performance of the receiver.

The present disclosure provides a system, apparatus and method to reduce phase noise associated with a received data signal, while optimizing system performance. An optimal length of a digital filter, employed in a carrier phase recovery process, is determined such that phase noise is reduced in the received data signal. Reduction of the phase noise present in the received data signal leads to improved receiver performance. The optimal length of the digital filter may be continuously performed, resulting in optimal performance of the receiver.
The following description is set forth for purpose of explanation in order to provide an understanding of the various embodiments of the disclosure. However, it is apparent that one skilled in the art will recognize that these embodiments, some of which are described below, may be incorporated into a number of different systems and devices. Additionally, the embodiments of the present disclosure may include certain aspects each of which may be present in hardware, software, or firmware. Structures and devices shown in block diagram in the figures are illustrative of exemplary embodiments and are meant to avoid obscuring certain aspects of the embodiments of the disclosure. Furthermore, connections between components within the figures are not intended to be limited to direct connections. Rather, data between these components may be modified, re-formatted or otherwise changed by intermediary components.
FIG. 1 illustrates a general block diagram of a portion 102 of an optical receiver 100. The optical receiver 100, for example a coherent receiver, receives an optical signal 104 in a modulation format employing PSK, for example. The optical signal 104 is provided by a first laser located in a transmitter (not shown). The optical signal 104 may be mixed with another optical signal provided by a second laser (not shown) local to the receiver in an optical-to-electrical (O/E) conversion circuit 110. The mixed optical signal is then converted into the electrical domain by the O/E conversion circuit 110 to provide corresponding in-phase (I) and quadrature signals (Q), referred to collectively herein as an I/Q signal. The I/Q signal is provided as a data signal 112 output from the conversion circuit 110. The I/Q signal may include a stream of contiguous symbols, each of which representing one or more bits of data encoded on the received optical signal 104 depending on the particular modulation format employed. For example, for an optical signal 104 having a QPSK modulation format, each of the symbols of a corresponding I/Q signal represents 2 bits of encoded data.
Graph 114 of FIG. 1A depicts the data signal 112 in a complex plane with respect to I and Q axes. The I and Q axes may also be referred to as the real and imaginary axes, respectively. The I and Q axes divide the complex plane into four portions or quadrants Q0, Q1, Q2, Q3, such that the data signal 112 has portions in each quadrant Q0-Q3. Phase noise, which may exist in the optical signals output from either, or both, the first and second lasers causes the data signal 112 in the complex plane to rotate over time about an origin O. As a result, the data signal may be represented as a doughnut shape plot about the origin O for example. Additionally, additive noise present in the data signal 112 impacts the amplitude of the data signal 112, defining the width of the doughnut for example.
The data signal 112 may then be provided to a phase recovery circuit 120 which provides some correction to reduce the additive noise present in the data signal 112, such that an estimation of the phase noise can be performed. The phase recovery circuit 120 includes a filter 124, described with respect to FIG. 1B below, which filters, or otherwise provides a weighed average, of the additive noise present in the data signal 112. The phase recovery circuit 120 then compensates for a portion of the phase noise present in the data signal 112, and provides a compensated data signal 122 at an output of the phase recovery circuit 120. Graph 116 depicts the compensated data signal 122 in the complex plane as a data constellation. Since the phase noise in the compensated data signal 122 has been partially compensated, individual constellation points within each of the individual quadrants Q0-Q3 are more readily apparent. The compensated data signal 122 is then provided to data processing circuitry 130 which analyzes the compensated data signal 122 to provide a feedback signal 132 to the phase recovery circuit 120. The feedback signal 132 may then be utilized to further optimize the performance of the phase recovery circuit 120, and the overall performance of the optical receiver 100, by further reducing the phase noise present in the data signal 112. The data processing circuitry 130 may also be configured to decode the I/Q signal into data which is provided as an output 134. Alternatively, the data processing circuit 130 may pass the compensated signal 122 as the output 134, another system or circuit (not shown) providing the data decoding function.
Turning to FIG. 1B, one exemplary filter 124 which may be employed in the phase recovery circuit 120 of the receiver 100 of the various embodiments of the present disclosure will be described in greater detail. Phase recovery circuit 120 may be similar to feed-forward carrier recovery circuits known in the art, for example. The filter 124 receives a data signal 112a and provides an output signal 129 in response to the received data signal 112a. The data signal 112a may be similar to, or derived from, the data signal 112. For example, the phase recovery circuit 120 may include additional elements which may be used to process the data signal 112 into the data signal 122a prior to reaching the filter 124. The filter 124 may include n taps, labeled T1 through Tn, collectively referred to as taps Tn. Each of the taps Tn may include amplifiers 127 which may be used to amplify or attenuate a signal propagating through the corresponding tap by an amount, represented by a coefficient dn. For example, a signal propagating through tap T1 may be amplified or attenuated by the associated amplifier 127 in tap T1 by an amount corresponding to d1. The filter may also include delay units 125, labeled "Delay 1" through "Delay n−1", positioned between successive taps. The filter 124 receives and delay-shifts the data signal 122a through each of the delay units 125 along paths 126. The signals provided by taps 1 through taps Tn, some of which are delayed by one or more delay units 125, are summed in a summer 128 to provide the output signal 129, which is further employed to reduce additive noise in the received signal 112, such that phase noise may be estimated. The length of the filter 124 may be described as a filter length of n, n equal to or greater than 1, e.g. the number of the taps Tn employed by the filter 124 having a non-zero coefficient dn. The filter length may be increased, for example, by changing one of the tap coefficients dn from a setting of zero to a non-zero value. Additionally, the filter length may be decreased by changing one of the tap coefficients dn from a non-zero value to a value of zero. Under certain circumstances the length of the filter 124 may be 1, while under other circumstances the length of the filter may be much longer. The output signal 129 may be further processed by the phase recovery circuit 120 to provide the compensated data signal 122, the output signal 129 from the filter 124 further processed by one or more additional elements (not shown) of the phase recovery circuit 120 for example.
The functionality of the filter 124, that is, the control and setting of the length of the filter 124, may be provided by one or more integrated processing chips as part of the phase recovery circuit 120, or part of the portion 102 of the receiver 100. Each of the one or more integrated processing chips may be, for example, in the form of an application specific integrated circuit (ASIC), a programmable gate array (PGA), field-programmable gate array (FPGA), or the like. Each of the integrated processing chips may be configured to be self-controlled or controlled by a controller (not shown) located external to the phase recovery circuit 120. Alternatively, the filter 124 may be controlled through a processor under software control, in the form of firmware executed by the processor for example.
FIGS. 2A-2C depict different exemplary representations of the data signal 122 which may be processed, in part, by the phase recovery circuit 120. FIG. 2A depicts a data constellation or graph 200A of a compensated data signal 122A, similar to compensated data signal 122, after being processed by the phase recovery circuit 120, including the filter 124 employing a length of 15, e.g. 15 taps are employed by the filter 124. As indicated, the corresponding performance of the receiver 100 is Q=9.41 dB. For a compensated data signal having a M-PSK modulation format, where M=2N, and N being an integer greater than 0, the corresponding constellation would include M constellation points. Accordingly, since the compensated data signal 122A is in a 4-PSK modulation format in the examples depicted in FIGS. 2A-2C, the data constellation 200A includes four constellation points 242A. Each of the constellation points represents a demodulated data symbol, representing one or more bits of data for example. For a 4-PSK signal, there are four constellation points 242A. A first constellation point 242A of quadrant Q0, for example, may represent the multiple bits of 0,0. A second constellation point 242A of quadrant Q1 may represent bits 0,1, a third constellation point 242A of quadrant Q2 may represent bits 1,1, and a fourth constellation point 242A of quadrant Q3 may represent bits 1,0.
As depicted in FIG. 2A, since the effect of phase noise has been mitigated, data of each of the constellation points 242A has a generally circular shape indicated by circle 244A. Only one centroid 242A and corresponding circular shape 244A is shown for purposes of clarity. As used herein, the term 'centroid' is to be generally defined as the center of the data distribution for each constellation point of a data constellation. For a signal in a 4-PSK modulation format, as the compensated data signal 122A, each of the four constellation points have centroids located on a line which passes through the origin O and bisects the associated quadrant Q0-Q3, for example line C which bisects quadrant Q0.
FIG. 2B depicts a data constellation or graph 200B of a compensated data signal 122B, similar to data signal 122, after being processed by the phase recovery circuit 120, including the filter 124 having a length of 5, e.g. 5 taps employed by the filter 124. As indicated, the corresponding performance of the receiver 100 decreases to Q=9.10 dB as the length of the filter 124 decreases from 15 to 5. The data constellation 200B includes constellation points 242B, one per quadrant Q0-Q3, and each having a centroid 244B. However, the data distribution of each constellation point 242B is represented by the tear-drop shape 244B of the compensated data signal 122B, as depicted in quadrant Q1. As the data distribution of the constellation points transition from a circular shape, such as constellation points 242A of FIG. 2A, to a tear-drop shape, such as constellation points 242B of FIG. 2B, the performance of the receiver 100 may degrade, which may lead to errors in the data decoding process. Data distributions as depicted in FIG. 2B, for example, can lead to increased bit error rates, resulting in poor performance of the receiver 100.
FIG. 2C depicts a data constellation or graph 200C of a compensated data signal 122C after being processed by the phase recovery circuit 120 including the filter 124 having a filter length of 101, e.g. 101 taps employed by the filter 124. As compared with the graph of FIG. 2A, the corresponding performance of the receiver 100 decreased to Q=7.73 dB as the length of the filter 124 increases from 15 to 101. The data constellation 200C includes constellation points 242C, one per quadrant Q0-Q3, and each having a centroid 244C. Similar to the compensated data signal 122B of FIG. 2B, the data distribution in each quadrant Q0-Q3 of the data constellation 200C is non-circular. Rather, each constellation point 242C has a non-circular or elliptical shape represented by the ellipse 244C around each centroid 242C. As stated above with respect to the tear-drop 244B shape of the constellation points 242B of FIG. 2B, the elliptical shape 244C of the constellation points 242C may lead to increased bit error rates, resulting in poor performance of the receiver 100. Thus, FIG. 2A depicts a desired data output, under most circumstances, while FIGS. 2B and 2C depict situations where the selected or determined length of the filter 124 is either two short (FIG. 2B) or too long (FIG. 2C). It is advantageous to optimize the performance of the filter 124 by selecting the appropriate filter length, resulting in improved performance of the receiver 100, such that the data has a circular distribution about each constellation point.
FIGS. 3A-3F depict a first exemplary algorithm for determining an optimal length for filter 124. FIG. 3A depicts a data constellation or graph 300A corresponding to the compensated data signal 122C of FIG. 2C. The graph 300A includes a first axis A and a second axis B which define each of the four quadrants Q0-Q3. The A axis and the B axis intersect at an origin identified as O. The A axis may also be referred herein as the I axis or the real axis, while the B axis may also be referred herein as the Q axis or the imaginary axis. The data 3D in quadrants Q1, Q2, and Q3 may be discarded, resulting in data 3D0 as depicted in Graph 300B of FIG. 3B. As should be readily apparent to one of ordinary skill in the art, while the first exemplary algorithm of FIGS. 3A-3F does not include that portion of the data 3D within quadrants Q1, Q2, and Q3, all or a portion of such data may be included in alternative algorithms, as discussed in greater detail below with respect to FIGS. 6A-6C for example. FIG. 3C depicts the data 3D0 rotated by an angle α about the origin O, defining a B1 axis offset from the B axis by α degrees and an A1 axis offset from the A axis by α degrees (A1 and B1 axes shown in dashed line). The data 3D0 may be rotated any suitable angle α such that the data 3D0 is equally distributed about the A axis, for example approximately one-half of the data 3D0 being in the quadrant Q0 and the remaining one-half of the data 3D0 being in the quadrant Q3. The data 3D0 need not be evenly distributed about the A axis, however such un-even distribution may result in error, which may decrease the overall performance of the receiver 100. The data 3D0 is generally distributed throughout the quadrant Q0 such that rotation of the data by the angle α of −45 degrees (clockwise) will result in a substantially an even distribution of the data 3D0 about the A axis, for example about one-half of the data being above the A axis while about one-half of the data being below the A axis. Rotation of the data 3D0 may be performed through any suitable means. For example, rotation of the data 3D0 may be achieved through the execution of a matrix operation, the complex data 3D0 being rotated about the origin O by the angle α. A new axis system may then be defined relative to a centroid 332C, or other desired point, of the rotated data 3D0. The new axis system is depicted in FIGS. 3C-3F by line L1 and line L2, line L2 being overtop the A axis.
Returning to FIG. 3A, a portion X of the data 3D0 crosses over the boundary between quadrants Q0 and Q3, as well as between quadrants Q0 and Q1. Thus, when the data 3D corresponding to quadrants Q1, Q2, and Q3 is deleted or removed to form data 3D0, not every symbol as part of the data 3D0 is present. These missing symbols, e.g. the data associated with quadrant Q0 but not part of the data 3D0, may be estimated through statistical analysis of the data 3D0. Alternatively, a subset of symbols forming data 3D0, as depicted in FIG. 3D, may be considered in optimization of filter 124. With the lines L1, L2 traveling through the centroid of the data 3D0, that portion of data 3D0 having a real component less than that associated with line L1 is deleted to form new data 3D0.1, as defined in FIG. 3D.
As shown in FIG. 3D, the lines L1 and L2 may intersect an origin OL. Lines L1 and L2 may be described as being along the major and minor axis of a geometric shape encompassing the data 3D0, an elliptical shape for example. Considering that portion of the data 3D0.1 in the quadrant Q0 defined by the L1 and L2 axes, e.g. the upper-right quadrant, the extent the data 3D0.1 is distributed along the L1 axis may be defined as a length R1, while the extent the data 3D0.1 extends along the L2 axis may be defined as a length R2. The length R1 may be defined as a circumference of the geometric shape encompassing the data 3D0.1. As used herein, the term circumference is the distance from the centroid of quadrant data, such as data 3D0, and extending outward to an outer boundary of the geometric shape. The geometric shape need not be a circle, but may be any geometric shape formed by the data 3D0, such as an elliptical shape or a tear-drop shape. As depicted, the length R1 is greater than the length R2, such that a difference between the length R1 and the length R2 is not zero. The difference between the length R1 and the length R2 may be minimized such that the geometric shape of the data 3D0 is more circular, as the circular shape 232A in FIG. 2A. In order to equalize the lengths R1 and R2, such that the difference between the lengths R1 and R2 is reduced to zero for example, the length of the filter 124, for example the taps employed by the filter 124, is preferably correspondingly decreased. As the length of the filter 124 is decreased the algorithm discussed with respect to FIG. 3 may be continuously performed to identify the corresponding values of lengths R1 and R2 until the difference between the lengths is near to or equal to zero. More specifically, with length R1 greater than length R2, the number of taps of the filter 124 may be decreased by a value, 1 for example. A decrease in the filter length need not be abrupt, setting one of the non-zero coefficients dn of one of the taps Tn instantaneously to zero for example. Rather, the filter length may be decreased through successive decrease in one or more of the non-zero coefficients dn corresponding to one or more taps Tn until at least one of the non-zero coefficients is zero. For purposes herein, such a successive decrease is deemed to be included as decreasing the filter length of the filter 124. The change in the filter length of the filter 124, as well as a change in the noise, phase noise or additive noise, which may be present in the compensated data signal 122, will then result in a different distribution of the data 3D0.1 with respect to the origin OL. The algorithm of FIG. 3 may then be repeatedly performed in an attempt to reduce the difference between the lengths R1 and R2 to zero, in light of the noise present in the compensated data signal 122.
The determination of the lengths R1 and R2 is one such determination to describe the distribution of the data 3D0.1 about the origin OL. For example, rather than lengths along the L1 and L2 axes, R1 and R2 may represent variances of a portion of the data 3D0.1 within quadrant Q0 with respect to the L1 and L2 axes. For purposes herein, a variance may be constructed to mean the quantity equal to the square of the standard deviation with respect to a group of data, such as that portion of the data 3D0.1 within quadrant Q0. For illustration purposes only, considering the symbols of a portion of data 3D0.1, each symbol of the portion including a positive imaginary portion and a positive real portion, R1 may represent a first variance with respect to the L1 axis, and R2 may represent a second variance with respect to the L2 axis. Similar to the analysis above, the first variance value of R1 is greater than the second variance value of R2 and the difference of the first variance value of R1 and the second variance value of R2 may be reduced to improve the performance of the receiver 100. A decrease in the filter length of filter 124 will result in the corresponding decrease in the difference of the first and second variances of R1 and R2, respectively. The length of the filter 124 may be further decreased until the difference between the variances R1 and R2 is near, or equal, to zero. When the variances R1 and R2 are substantially equal, the corresponding length is the desired length for the filter 124, and the performance of the receiver 100 may be optimized.
Turning to FIG. 4A, a graph 400A depicts exemplary plots of a cumulative density function (CDF), as well know in statistics, with respect the real and imaginary portions of each symbol of that portion of the data 3D0.1 which includes a positive real portion and a positive imaginary portion. More specifically, graph 400A depicts a first curve 450 which represents the first variance R1 along the imaginary axis and a second curve 452 represents the second variance R2 along the real axis. As depicted, the first curve 440 is shifted a positive direction from the second curve 442. As the length of the filter 124 is decreased, the first and second curves move toward each other until the first curve 440 overlaps the second curve 442. The length of the filter 124 when the first curve 440 overlaps the second curve 442 is the desired length for the filter 124.
A graph 400B of FIG. 4B depicts exemplary plots of the performance of the receiver 100 and the I/Q variance difference, e.g. the difference between the first variance R1 and the second variance R2, for an exemplary data signal, such as data signal 122C. A first curve 454 represents the performance of the receiver 100 in terms of the quality factor, Q, of the receiver 100 versus the length of the filter 124, employed as part of the phase recovery circuit 120. As shown, as the filter length increases, the performance of the receiver 100 improves, reaches optimum performance, discussed in greater detail below, and then gradually drops off. A second curve 456 of FIG. 4B represents the I/Q variance difference versus the length of the filter 124. As depicted, as the difference of the first variance R1 and the second variance R2 goes from a positive value toward zero, the length of the filter 124 increases from 1 to approximately 23. As the difference of the first and second variances R1, R2 continues to decrease from 0 toward 0.01, the length of the filter 124 continues to increase from approximately 24. As mentioned above, when the first and second variances R1, R2 are equal, the length of the filter is optimized to provide optimum performance of the receiver 100. Thus, the I/Q variance difference of zero corresponds to receiver 100 performance of approximately Q=8.8 dB, as indicated by dashed line S.
Turning back to FIG. 3E, a graph 300E depicts data 3D0.2 which is derived from the data 3D0.1 by moving or folding those symbols below the L2 axis, e.g. having a negative imaginary portion, into that portion of the data D2.1 which exists above L2. For example, the data 3D0.2 may be formed by setting the imaginary portion of each symbol of the data 3D0.1 to the absolute value of the imaginary portion. Once the data 3D0.2 is defined, the analysis related to the calculation of the variances R1 and R2 may be performed. For example, since the variance R1 is greater than the variance R2, as performed by the data processing circuit 130 for example, a correction or error feedback signal 132 is provided back to the phase recovery circuit 120, which adjusts the length of the filter 124 in response to the received error feedback signal 132. In this case, the length of the filter 124 is decreased.
Turning to FIG. 3F, a graph 300F depicts the result of the algorithm of FIGS. 3A-3E performed with respect to the tear-drop shaped compensated data signal 122B as depicted in FIG. 2B. As shown, the variable R1 is less than the variable R2, whether R1 and R2 represent a length or a variance with respect to the data 3D0.2 of FIG. 3F. Thus, the length of the filter 124 is increased to equalize the difference between R1 and R2. As stated above with respect to data 3D0.2 of FIG. 3E, when the variances or lengths R1 and R2 are substantially equal, the corresponding length is the desired length for the filter 124, e.g. reducing phase and additive noise present and increasing performance of the receiver 100. While the algorithm of FIGS. 3A-3F describe aligning the centroid 342 of the constellation point 340 with respect to the real axis, such alignment is for illustration purposes only. For example, the centroid 342 need not be rotated at all, as discussed in FIGS. 5A and 5B below, or if preferred due to the availability of processing resources, may be rotated any amount about the origin O.
Turning to FIGS. 5A and 5B, another algorithm in accordance with certain embodiments of this disclosure is illustrated. FIG. 5A depicts data 5D0 of quadrant Q0, data 5D0 being similar to data 3D0 for example. Rather than rotating or repositioning, e.g. further processing, the data 5D0, the L1 axis and the L2 axis are positioned within the quadrant Q0 as depicted in FIG. 5B. The L2 axis passes through the origin O of the complex plane and the centroid of the data 5D0 of quadrant Q0, while the L1 axis of FIG. 5B is orthogonal to the L1 axis and passes through the centroid of the data 5D0. Using similar techniques as discussed with respect to the L1 and L2 axes of the embodiment depicted in FIGS. 3C-3F, the data 5D0.2 is defined. A first variance R1 of the data 5D0.2 and a second variance R2 of the data 5D0.2 are further defined relative the geometric shape of data 5D0.2. From the variance values R1, R2, an I/Q variance difference may be calculated and a corresponding length of the filter 124 may be determined, as discussed in detail above with respect to FIGS. 3C-3F.
Turning to FIG. 6A, yet another algorithm in accordance with certain embodiments of this disclosure will be discussed in greater detail. FIG. 6A depicts a data constellation of data 6D, similar to that of data 3D depicted in FIG. 3A. The data 5D includes individual quadrant data 6D0-6D3 corresponding to quadrants Q0-Q3, respectively. Rather than processing the data 6D0 of quadrant Q0, a more accurate determination of the variances R1 and R2 may be determined if the complete data 6D set is taken into consideration. Turning to FIG. 6B, the data 6D1 of quadrant Q1 may be folded into the data 6D0 of quadrant Q0. The data 6D1 may be folded into the quadrant Q0 by setting the real part of each symbol of the data 6D1 to the absolute value of the real part of each symbol or by converting each symbol of the data 6D1 by setting the real part of each symbol to the absolute value of the real part of each symbol. Alternatively, each of the symbols of the data 6D1 may be rotated an angle α degrees about the origin O, through a matrix operation for example. For example the data 6D1 may be rotated 90 degrees (clockwise) about the origin O. In any case, the data 6D1, 6D0 are merged in quadrant Q0. In similar fashion, the data 6D2 of quadrant Q2 may be folded or rotated into the data 6D3 of quadrant Q3. Turning to FIG. 6C, the data 6D2, 6D3 of quadrant Q3 may then be folded about the A axis or rotated 90 degrees (counter-clockwise) about the origin O such that the complete data 6D, e.g. data 6D0-6D3, exists solely in the quadrant Q0. The analysis to determine the adequate length of the filter 124 may then proceed as illustrated and discussed in greater detail with respect to FIGS. 3C-3F, for example. By combining all the symbols of the data 6D into one quadrant, a more accurate determination of the length of the filter 124 can be achieved.
As is true with other algorithms discussed herein, while the algorithm of FIGS. 6A-6C was described with respect to combining the complete data 6D in the quadrant Q0, each individual data 6D0-6D3 may be combined in other ones of the quadrants Q1, Q2, or Q3 prior to being rotated between quadrants Q0 and Q3 as depicted in FIG. 3C, or otherwise further processed to obtain the optimum length of the filter 124. Further, as with other algorithms discussed herein, performance of the particular algorithm does not require the processing of every data point, as part of data 6D for example. Rather, one may consider a limited number of data points, representative of the data constellation which the data represents for example, the optimum filter length being determined from the limited number of data points.
While the various algorithms described herein make reference to aligning the centroids of the various constellation points at specific locations, such alignment at specific locations is for illustration purposes only. For example, with reference to the algorithm of FIGS. 6A-6C, the centroids 642 of each of the constellation points 640 may be aligned at any point along a circle 643 whose center is at origin O and which passes through each of the centroids 642, as depicted in FIG. 6A. Once aligned, the data processing can continue to determine the corresponding variables R1 and R2 and, ultimately, the length of filter 124 as part of the phase recovery circuit 120, as described herein.
The various algorithms described herein may apply to any data signal having a M-PSK modulation format, where M=2N, for N being an integer greater than 0. Turning to FIGS. 7A-7E, another exemplary algorithm will be described in greater detail. FIG. 7A depicts a data constellation corresponding to data 7D of a data signal 712 in a modulation format 8-PSK. The processing of such data 7D will result in a compensated data signal 722 having eight constellation points 740. As shown and for illustration purposes only, each of the constellation points 740 may have an elliptical shape 744 surrounding a centroid 742. The compensated data signal is distributed as data 7D0-7D3 across quadrants Q0-Q3, respectively. As discussed with respect to Data 6D of FIGS. 6A-6C, the data 7D1 of quadrant Q1 may be folded about the B axis as indicated by arrow A3 or rotated an angle α into quadrant Q0, a being 90 degrees for example, as shown in FIG. 7B. Similarly, the data 7D0 of quadrant Q2 may be folded about the B axis as indicated by arrow A3 or rotated an angle α of −90 degrees (counter-clockwise) into quadrant Q3. As depicted in FIG. 7C, the combined data D3, D4 of quadrant Q3 may then be folded into quadrant Q0 as indicted by arrow A4, or rotated and angle α of 90 degrees (clockwise) about the origin O. Once the data 7D is positioned within the quadrant Q0, the centroids 742 of each constellation point 740 is then aligned. As shown in FIG. 7D, for example, constellation data 7D0-1 may be folded about a dashed line F1 as indicated by arrow A51. Alternatively, the constellation data 7D0-1 may be rotated an angle α1 with respect to the B axis, the angle α1 being approximately 45 degrees (clockwise) for example. Similarly, the constellation data 7D0-2 may be folded about a dashed line F2 as indicated by arrow A52. Alternatively, the constellation data 7D0-2 may be rotated an angle α1 with respect to the A axis, the angle α1 being −45 degrees (counter-clockwise) for example. The resultant data 7D0-7D3 is merged together within the quadrant Q0, the data 7D0-7D3 collectively having a centroid 742C which is positioned along a line C which also passes through the origin O, as shown in FIG. 7E.
The variances or lengths R1 and R2 associated with the data 7D0-7D3 can then be calculated to define a feedback or correction signal, as described in more detail above. For example, the processing circuit 130 of FIG. 1A then provides the feedback or correction signal 132 to the phase recovery circuit 120. The length of the filter 124, as part of the phase recovery circuit 120, may then be adjusted to an optimum value to improve the performance of the receiver.
Turning to FIG. 8, a method 800 in accordance with certain aspects of the embodiments of the disclosure is shown. In a step 802, a plurality of symbols are received, the plurality of symbols part of a compensated data signal similar to compensated data signal 122 of FIG. 1A. The symbols of a first quadrant of a data constellation may then be combined with symbols from one or more of the three remaining quadrants in an optional step 804 to provide additional data symbols for analysis in the determination of an optimum length of the filter 124. If applicable, the combined symbols may be from any of the four quadrants. A portion of the symbols are then analyzed, in a processing circuit similar to circuit 120 for example, to provide a feedback or correction signal similar to the correction signal 132 in a step 806. For example, a first variance and a second variance may be determined with respect to the portion of the symbols, and based upon the difference of these variances the feedback or correction signal is provided, as described in greater detail above. The portion of the symbols may include symbols from any combination of symbols of the individual quadrants, such as quadrants Q0-Q3 of FIG. 3A, depending on whether the optional step 802 is performed. In certain cases, all the symbols may be combined in a signal quadrant for processing. The feedback or correction signal is then provided to the phase recovery circuit in a step 808, the length of a filter, such as filter 124 as part of the phase recovery circuit 120 of FIG. 1A, being adjusted according to the feedback or correction signal as described in greater detail above, optimizing the filter, and ultimately the optical receiver, performance.
While the various embodiments of the disclosure have been described in conjunction with several specific embodiments, it is evident to those skilled in the art that many further alternatives, modifications and variations will be apparent in light of the foregoing description. Thus, the embodiments described herein are intended to embrace all such alternatives, modifications, applications and variations as may fall within the spirit and scope of the appended claims.

Carrier phase estimation filter length optimization


Certain embodiments of the present disclosure relate to chamber liners, processing chambers that include chamber liners, and methods of using the same. In one embodiment, a processing chamber comprises a chamber body defining an interior volume and comprising an access port for inserting a substrate into the interior volume; a cathode assembly configured to generate a plasma within the interior volume; and a chamber liner comprising a smooth interior surface that is radially symmetric about a vertical axis of the chamber body. The chamber liner is configured to move between a loading position and an operation position.

Integrated circuits are made possible by processes which produce intricately patterned material layers on substrate surfaces. Etch processes, deposition processes, and cleaning processes may be performed in a variety of chambers. These chambers may include components that facilitate the formation of capacitively-coupled or inductively-coupled plasmas, for example. A key aspect of plasma reactor design is internal reactor symmetry, where the symmetry of the electrical field in the plasma reactor induced by RF-biased electrodes can have a significant impact on the reactor performance. Current systems, however, generally contain internal components that introduce asymmetries into the reaction volume, often resulting in non-uniform etch rates and other negative effects, such as wafer tunneling effects.

Continuous liner for use in a processing chamber


Vector-based images and documents, such as those written in SVG and Adobe Flash, can be converted into equivalent bitmap or other non-vector-based image by parsing the vector-based image to detect objects in the vector-based code. For each detected object, a separate bitmap of the object is created and information about where that image lies on the z-axis is retained. A separate bitmap image is created for each object, and the separate bitmap images are layered on top of one another, which is to say ordered along the z-axis in accordance with their z-axis coordinates. Animation of an image can be implemented by selectively rendering different ones of the bitmap images as transparent.

This invention relates to image rendering with computers and software and more particularly to devices and software components for translating vector graphic documents into bitmapped documents.
Scalable Vector Graphics (SVG) is a computer-readable language that is based on eXtensible Markup Language (XML) and is used for representing static and dynamic vector graphic images. SVG is able to define two-dimensional images using tags conforming to XML that determine the images' attributes (e.g., size, shape, color, etc.). SVG is able to display not only the shapes of two-dimensional vector graphic images but also bitmapped graphics and text. SVG is vector-based, which means content is not written for specific screen resolutions and sizes but can easily be scaled. SVG is standardized by the World Wide Web Consortium (W3C), which has adopted SVG version 1.1 as a W3C Recommendation.
HyperText Markup Language (HTML) is another computer-readable language that is written using tags and at least in that respect is similar to XML. XHTML is a version of HTML that is conformant to XML. From the beginning, HTML was intended to represent the logical structure of text, not graphics, in content such as documents and web pages. Images are represented in HTML as bitmaps. The physical representation of headings, paragraphs, etc. is determined by the browser that renders the HTML code. As time passed, more control over the visual appearance of web pages became desirable with HTML. Tags, such as the font tag, were introduced that enabled web and other content developers to specify the typeface, size, weight, and color of text in HTML pages. Using table elements with zero-width borders, it became possible to do advanced layout and positioning of page contents, but the HTML code became cluttered and hard to comprehend. Today, HTML is again written to represent the structure of documents, leaving presentation-related formatting to Cascading Style Sheets (CSS), which is a mechanism for adding styles (e.g., fonts, colors, spacing, etc.) to web pages and documents.
In recent years, web applications have emerged, which are web pages that try to mimic the behavior of regular software applications. For example, modern browsers support JavaScript, which is another computer-readable language, and HTML documents are accessible through the Document Object Model, which is a W3C-standard, object-oriented Application Program Interface (API) for accessing content elements, such as images on a web page, as objects. JavaScript is one of many types of scripting logic that can be inserted or embedded in a web application (or web content or web page) and executed by a processor in displaying a web page.
The Third Generation Partnership Project (3GPP), which promulgates specifications for many electronic communication systems, adopted SVG 1.1 for the 3GPP Release 5 specifications, and SVG is today used by roughly 100 million mobile telephone handsets and other user equipments (UEs) for generating and displaying images. For example, UEs now routinely access the World Wide Web with browser applications that adjust images and other downloaded content for the commonly smaller screens included in those equipments.
Specification of SVG Tiny 1.2 is under development by W3C for SVG version 1.2. SVG Tiny is specifically designed for mobile devices, which typically have limited memory and processing resources. SVG Tiny 1.2 has also been adopted by 3GPP for the Release 6 specifications. Support for a variety of new multimedia features, including full control of audio and video, is included along with micro DOM (μDOM) and scripting. μDOM is a subset of the Document Object Model (DOM). Some SVG attributes can be manipulated by μDOM scripts, enabling many kinds of animation. Objects can be added or removed to create dynamic content on the page.
Among other things, SVG and other vector-based representations facilitate animation because information about background objects currently hidden from view by foreground objects is not lost. Consequently, when a foreground object is made to appear in a different location in a different image, it is possible to include the formerly hidden background object(s) in that different-location image. In particular, SVG uses a "painters model" of rendering, in which "paint" is applied in successive operations. In other words, an electronic processor renders an object on an output device or display by carrying out a succession of "paint" operations. With each operation, the processor paints over a corresponding area of the output display, and when an area being painted overlaps a previously painted area, the new paint partially or completely obscures the old paint.
Because images defined in HTML are bitmaps, information about the appearance of a background object hidden by a foreground object does not exist. This lack of information makes it difficult for a processor to render formerly-background objects when foreground objects are made to appear in different locations.
It is straightforward to convert an SVG or equivalent vector-based image to a bitmap image, but doing so has a number of drawbacks. For example, it is very difficult (even impossible) to change an image, e.g., to show motion, once it has been converted from SVG, for example, to a bitmap image. As noted above, information about the appearance of background objects hidden by foreground objects that was present in the SVG or other vector-based representation does not exist in the HTML or other non-vector-based representation. Moreover, advanced applications in SVG are not executable by many UEs because SVG Tiny 1.2 is not yet fully deployed and SVG is not be supported on every type of UE.
It is desirable to be able to be able to convert SVG and equivalent vector-based images into bitmaps and equivalent non-vector-based images because this would enable the display of SVG-originated and other vector-graphic content on more types of UEs and other display devices.


The present invention discloses a network address conversion system and the method thereof, which applies to products of VoIP and is compliant with Q.931 and H.245 protocols used by the videophone. The network address conversion system according to the present invention comprises a private network, a public network, a NAT router and a network server. The NAT router is used to convert the private IP address of the data packet from the private network into a public IP address for entering the public network, and to convert the public IP address of the data packet from the public network into a private IP address for entering the private network. The network server is connected to the public network to execute a public IP address query program, and then transmits the public IP address back to the node in the private network.

1. Field of the Invention
The present invention relates to a network address conversion system and the method thereof, more particularly to a system using a network server for performing network address conversion and the method thereof.
2. Background of the Invention
In order to solve the problem of increasingly insufficient public IP addresses, RFC1918 defines three domains for private IP addresses, 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255, and 192.168.0.0 to 192.168.255.255, respectively. The private IP addresses may be used to connect computers in an enterprise in view of not needing to additionally apply for more public IP addresses. However, because a plurality of private IP addresses will be converted into the same public IP address when they connect to the external public network, the object of saving IP addresses needs to be achieved. Nevertheless, because the plurality of private IP addresses share the same public IP address, the data packets should be performed in an IP address conversion through a router between the public network and the private network within an enterprise.
A common conversion method between the private IP address and the public IP address is the Network Address Translation (NAT) defined by RFC1631. The conventional network address conversion system 10, as shown in FIG. 1, uses a NAT router 12 to convert the source address included in the IP header of the data packet from the private network 11 into the public IP address of the public network 13, and convert the source address included in the IP header of the data packet from the public network 13 into the private IP address of the private network 11. For example, a node in a private network 11 having a private IP address of 192.168.1.1 can be converted to a public IP address 188.8.131.52 through a routing table of the NAT router 12, and then communicate with a remote node in the public network 13.
For the application of transmitting high quality voice over IP (VoIP), such as the Q.931 and H.245 protocols used by the videophone, the Information of IP address in the IP header is not only included in the data packet, but also in the payload. However, the conventional NAT router 12 only handles the convertion of the private IP address in the IP header into a public IP address, and not the IP address conversion in the payload. Because the IP address in the payload has not been converted, the user of the videophone in the public network 13 cannot transmit his voice and image to the user of the videophone in the private network 11.
A conventional method for solving the above problem is to add A/P gateways 21 and 22 at both ends of the NAT router 12 in cooperation with the system service provider, as shown in FIG. 2, which is responsible for the IP address conversion in the payload. However, this method increases the cost burden of the manufacturing company. For individual users, because there are no system service providers that cooperates the A/P gateways 21 and 22, the above-mentioned solution cannot be used. Another solution is to use a specific NAT router having the function of converting the IP address in the payload, but this also results in high cost burden, which is difficult to be accepted in the market. Moreover, when using ADSL or cable modem, the public IP address dynamically changes, and is not fixed, so the difficulty of the design increases.
As described above, because the current VoIP applications in the market are concerned practical requirements of the user, effectively completing the communication and reducing the cost becomes very important issues.

Network address conversion system and the method thereof


The present disclosure provides compositions for inhibiting proteases, methods for synthesizing the compositions, and methods of using the disclosed protease inhibitors. Aspects of the disclosure include a peptidyl propenoyl hydrazide compositions that inhibit proteases, for example cysteine proteases, either in vivo or in vitro.

1. Technical Field
This disclosure relates generally to protease inhibitors and applications thereof, more specifically to peptide inhibitors of cysteine proteases, even more specifically to propenoyl hydrazides, methods of their use, and methods of their production.
2. Related Art
Protease inhibitors are important therapeutics in the treatment of a variety of disease conditions including viral infections such as HIV infection. Proteases are enzymes that cleave proteins or peptides and are classified into several groups. For example, cysteine proteases form a group of enzymes involved in numerous disease states, and inhibitors of these enzymes can be used therapeutically for the treatment of diseases involving cysteine proteases.
Cysteine Proteases.
Cysteine proteases employ a thiolate residue, which performs a nucleophilic attack on the amide bond of the peptide backbone to form a tetrahedral intermediate. The intermediate collapses to release the first product and the resulting acyl enzyme then undergoes hydrolysis. Based on their sequence homology cysteine proteases are divided into several clans and families. Clan CA and clan CD contain the majority of cysteine proteases. The majority of cysteine proteases, such as papain, calpains, cathepsins, and cruzain belong to the clan CA. According to the crystal structure of papain, clan CA proteases are unique for their catalytic triad formed by Cys, His, and Asn. The oxyanion hole is created by a preceding Gln residue. Clan CA enzymes are inhibited by E-64, a natural inhibitor of cysteine proteases, and cystatin. The substrate specificity of clan CA enzymes is primarily controlled by the S2 enzyme subsite. Clan CD enzymes are unique for their lack of inhibition by E-64 and their specificity for the P1 amino acid residue. Even though clan CD is the smallest of the clans, it contains some very important enzymes. Among them are caspases, legumains, gingipains, clostripain, and separase.
Caspases are a recently discovered family of cysteine endoproteases, which are highly selective for Asp at the P1 residue. As a result, this newly emerging family of proteases has been called caspases (cysteinyl aspartate—specific protease). All caspases contain the conserved pentapeptide active site motif Gln-Ala-Cys-X-Gly (QACXG)(SEQ. ID NO. 1), where X=Arg, Gln, Gly (R, Q, G), and are synthesized as inactive proenzymes. The only other mammalian protease with specificity for Asp is the lymphocyte serine protease, granzyme B. Many of the proteolytic cleavages that are observed during apoptosis and cytokine maturation are due to the action of various caspases. Indeed, many of the procaspases are activated by other caspases, which selectively cleave at P1 Asp residues in their recognition sites.
At present, there are 11 homologous members of the caspase family in humans. Some caspases are important mediators of inflammation, where they are involved in the production of inflammatory cytokines, and others are involved in apoptosis, where they participate in signaling and effector pathways. Group I caspases (caspases-1,-4, -5, -11, -12, -13, and -14) are primarily mediators of inflammation and are involved in proteolytic activation of proinflammatory cytokines. Caspase-1 is also involved in the Fas and TNFR apoptotic pathway. Group II caspases (caspases-2, -3, and -7) are late phase effectors of apoptosis and are involved in the cleavage of key structural and homeostatic proteins. Caspase-3, also known as CPP32 (cysteine protease protein 32-kDa), Yama or apopain, is believed to be one of the major effectors in apoptosis. This enzyme is a key executioner because it is responsible either partially or totally for proteolytic cleavage of key apoptotic proteins. It functions to decrease or destroy essential homeostatic pathways during the effector phase of apoptosis. Caspase-3 cleaves or activates nuclear enzymes, such as poly(ADP-ribose)polymerase (PARP), the 70 kDa subunit of the U1 small ribonucleoprotein, the catalytic subunit of DNA-dependent protein kinase, and protein kinase Cδ. Group III caspases (caspases-6, -8, -9, -10) are involved in the upstream early activation of effector caspases. Studies have shown that caspase-8 and -10 can cleave radiolabeled precursors for caspase-3. Caspase-6 is the only known caspase that cleaves the lamins, the major structural proteins in the nuclear envelope. Proteolysis of lamins is observed in cells undergoing apoptosis. Caspase-8 (MACH/FLICE), which can cleave all other known caspases, is suggested to lie in the pinnacle of the apoptotic cascade, at least when apoptosis is initiated by some stimuli such as Fas-L and TNF. Accordingly, the present disclosure encompasses compositions and methods of altering, inhibiting, or reducing the formation of enzymatic reaction products involving cysteine proteases. Inhibiting the formation of cysteine protease reaction products in vivo can provide therapeutic effects to patients suffering from unregulated or undesired protease activity.
Caspases have a specificity for at least four amino acids to the left of the cleavage site (P side). The S4 subsite is the single most important determinant of specificity among caspases after the P1 Asp. The optimal sequences of the caspases were obtained using a positional-scanning combinatorial substrate library (PS-CSL). The optimal recognition sequences for these enzymes are closely related to the sequences found in known macromolecular substrates. Group I caspases' optimal sequence is Trp-Glu-His-Asp (WEHD) (SEQ. ID NO. 2) with S4 favoring hydrophobic amino acids. Group II caspases' optimal sequence is Asp-Glu-X-Asp (DEXD) (SEQ. ID NO. 3) with a requirement for Asp in S4. Group III caspases' optimal sequence is N-Glu-X-Asp where N=Val or Leu, and X can be any amino acid ((V,L)EXD) (SEQ. ID NO. 4) with a preference for branched, aliphatic side chains in S4. The S3 subsite prefers glutamic acid (E) in most of the caspases, which could be explained by the salt link between Arg-341 (involved in stabilization of the P1 aspartic acid) and the glutamic acid in P3.
Legumains (EC.184.108.40.206, asparaginyl endopeptidase) form a another important family (C13) of clan CD proteases. They are related to caspases and other clan CD enzymes by a shared catalytic-site motif and a common scaffold within their catalytic domains. They were first identified in leguminous plants, and later in mammalian cells. In mammalian cells legumain has been linked to osteoclast formation and bone resorption, and the processing of bacterial antigens and the potential autoantigen, myelin basic protein, in the major histocompatability (MHC) class II system. In S. mansoni the legumain protease (SmAE, Sm32) is dissimilar to the other proteinases and may process gut-associated clan CA zymogens to their active forms, thus facilitating the digestion of ingested host serum proteins. S. mansoni legumain is not inhibited by the clan CA cysteine protease inhibitor E-64 or the diazomethane inhibitor Cbz-Phe-Ala-CHN2. Irreversible protease inhibitors would have great potential for the short-term therapeutic administration against parasitic infections. So far there has been no success in the determination of a crystal structure of the asparaginyl endopeptidase. Like all clan CD proteases, the substrate specificity of legumain is controlled by the interactions of the S1 subsite. Legumains selectively hydrolyze substrates with an asparaginyl residue in the P1 position. Legumain is less selective with respect to the P2 and P3 positions, but prefers Ala or Thr. The synthetic substrate Cbz-Ala-Ala-Asn-AMC was effectively cleaved by S. mansoni legumain and human legumain with KM's of 90 and 80 μM respectively.
Next to caspases and legumains, the family of separases has gained increasing attention among the clan CD enzymes. Separases play an important role during mitosis at the metaphase to anaphase transition. When the sister chromatids are aligned at the onset of the anaphase, separase initiates the segregation of the chromosomes by facilitating the breakdown of a cohesion complex between the individual sister chromatides.
Neural tissues, including brain, are known to possess a large variety of proteases, including at least two calcium-stimulated proteases termed calpains. Calpains are present in many tissues in addition to the brain. Calpain I is activated by micromolar concentrations of calcium while calpain II is activated by millimolar concentrations. In the brain, calpain II is the predominant form, but calpain I is found at synaptic endings and is thought to be the form involved in long term potentiation, synaptic plasticity, and cell death. Other Ca2+ activated cysteine proteases may exist, and the term "calpain" is used to refer to all Ca2+ activated cysteine proteases, including calpain I and calpain II. The terms "calpain I" and "calpain II" are used herein to refer to the micromolar and millimolar activated calpains, respectively, as described above. While calpains degrade a wide variety of protein substrates, cytoskeletal proteins seem to be particularly susceptible to attack. In some cases, the products of the proteolytic digestion of these proteins by calpain are distinctive and persistent over time. Since cytoskeletal proteins are major components of certain types of cells, this provides a simple method of detecting calpain activity in cells and tissues. Activation of calpains and/or accumulation of breakdown products of cytoskeletal elements have been observed in neural tissues of mammals exposed to a wide variety of neurodegenerative diseases and conditions. For example, these phenomena have been observed following ischemia in gerbils and rats, following stroke in humans, following administration of the toxins kainate, trimethyltin, or colchicine in rats, and in human Alzheimer's disease.
Cathepsin B is involved in muscular dystrophy, myocardial tissue damage, tumor metastasis, and bone resorption. In addition, a number of viral processing enzymes, which are essential for viral infection, are cysteine proteases. Inhibitors of cysteine proteases would have multiple therapeutic uses.
Other important cysteine proteases are the bacterial enzymes clostripain and gingipain. Gingipain causes tissue destruction during periodontal diseases.
Cysteine Protease Inhibitors.
To date, a structurally diverse variety of cysteine protease inhibitors have been identified. Palmer, (1995) J. Med. Chem., 38, 3193, discloses certain vinyl sulfones, which act as cysteine protease inhibitors for cathepsins B, L, S, O2 and cruzain. Other classes of compounds, such as aldehydes, niitriles, α-ketocarbonyl compounds, halomethyl ketones, diazomethyl ketones, (acyloxy)methyl ketones, ketomethylsulfonium salts and epoxy succinyl compounds have also been reported to inhibit cysteine proteases. See Palmer, id, and references cited therein. Many irreversible cysteine protease inhibitors have been described in the review by Powers, Asgian, Ekici, and James (2002) Chemical Reviews, 102, 4639. See Powers, id, and references cited therein. However, most of these known inhibitors are not considered suitable for use as therapeutic agents in animals, especially humans, because they suffer from various shortcomings. These shortcomings include lack of selectivity, cytotoxicity, poor solubility, and overly rapid plasma clearance.
Several types of Michael acceptor warheads have been employed as inhibitors for cysteine proteases. Among the most effective inhibitors are vinyl sulfones and α,β-unsaturated carbonyl derivatives against various cysteine proteases. Hanzlik, (1984) J. Med. Chem., 27, 711 has replaced the carbonyl group of a good substrate with a moiety, that would trap the enzymatic nucleophile (Ser-OH or Cys-OH) without altering the structural features required for enzyme recognition and binding. The fumarate derivative of the epoxy succinate E-64c, which is one of the first Michael acceptor inhibitors reported, extends the α,β-unsaturated carbonyl by an additional carbonyl for possible structural recognition and binding requirements within the enzyme active site. The fumarate derivative of E-64c (trans-HOOCCH═CH—CO-Leu-NH(CH2)2CH(CH3)2) inhibits cathepsin B (kapp=625 M−1s−1), cathepsin H (kapp=M−1s−1), and cathepsin L (kapp=2272 M−1s−1) irreversibly. Both the fumarate analog of E-64c and the epoxide parent compound do not inhibit clan CD proteases. Caspases, legumains, gingipains and clostripain are members of clan CD, while papain, cathepsins, and calpains are members of clan CA. Therefore, because of the aforementioned deficiencies in the art, there is a need for new compounds and methods for inhibiting proteases, in particular cysteine proteases.


A control system for controlling the operation of an electric motor driven door or gate operator unit having a speed reducing gear drive mechanism and a brake unit for positive braking of the motor output shaft. A programmable microcontroller is operably connected to a motor drive circuit with interlock relays to energize the drive motor for rotation in opposite directions. The motor drive circuit is interconnected with a motor watchdog circuit to effect motor shutdown if the microcontroller malfunctions and a brake release circuit to prevent motor operation unless the brake is energized. The microcontroller is operable to store door mid-stop time delay values, braking rates, a door position limit overrun signal, a door cycle count, door reversals upon receiving an obstruction detector signal and error codes associated with door operator and control system malfunctions. The brake may be controlled on a variable duty cycle to provide smooth braking action in both directions of movement of the door.

The present invention pertains to a control system for a motor driven door operator, primarily intended for industrial type doors, including sectional upward acting or rollup doors, gates and similar closures, and methods of controlling the door operator.
Motor operated doors particularly adapted for industrial applications desirably include motor controls which facilitate ease of operation of the door and provide for a long operating life in rigorous operating conditions. One type of door operator that has been developed for use with the present invention is operable to be driven by electric motors and may be adapted to automatically close in the event of a power failure or upon receiving a remote control signal, be manually operated to open or close and be adapted for use with motors of various power capacities and electric power sources. Still further, the operating requirements for commercial or industrial doors and gates have dictated other improvements in control systems for motor operated closures, including upward acting doors, in particular. The present invention provides certain improvements needed in this art.
The present invention provides an improved door operator control system for controlling a motor driven operator for doors, gates and upward acting doors, in particular.
In accordance with one aspect of the present invention a control system is provided which includes a programmable microcontroller and associated control circuits and is adapted for use with door operators driven by electric motors of various power capacities and power sources. The control system includes protective circuit elements to avoid damage to the control system caused by power source voltage transients, including overvoltages resulting from connection of a transformer of the wrong voltage rating, or major voltage surges such as induced by nearby lightning strikes.
In accordance with another aspect of the present invention a door operator control system is provided which includes improvements in circuitry for receiving signals indicating door travel limits, an advantageous arrangement of operator control elements for controlling a microcontroller unit of the control system and circuits for input signals from various sources including external interlock input signals and remote control input signals.
The control system of the present invention also includes circuits for connecting a microcontroller to motor drive relays or contactors including an interlock feature, a motor drive xe2x80x9cwatchdogxe2x80x9d circuit, a motor drive status feedback circuit, control circuitry for controlling a door operator which includes an operator brake, and an emergency operator shutdown circuit.
The control system of the present invention further includes a keypad for inputting control signals and calibration signals to a microcontroller via a serial communication bus to control door functions including door overrun of a position limit, braking rate of the operator brake, a mid position stop, clearing maximum run timers of the operator and correlating the motor direction of rotation with door direction of movement. The control system further includes a seven segment display and calibration indicators for displaying a condition code in the normal operating mode of the control system, calibration information when the control system is being operated in a calibration mode and error codes indicating a fault or error condition existing in the control system and the associated operator. The seven segment display includes a driver circuit including a multiplexed constant current source.
The present invention still further provides an improved method of operating a motor driven operator for opening and closing a closure device, such as an upward acting sectional or rollup door or a gate wherein improved braking action is imposed by and on the operator to control a braking rate of the door to minimize shock loads, wear and tear on the door and the operator, and to reduce noise associated with door operation.
The control system is also adapted to provide a method of operation which allows a door position limit overrun with variable progressively longer or shorter time delays between the time that a limit position is achieved and the door operator begins a braking procedure. In particular, when the door operator activates a switch determined to be the door down position limit switch, a user selectable time delay may be input to the controller, which time delay will delay motor shutdown and the onset of the braking procedure to allow the door bottom edge to seal against a floor or sill and without activating a door reversal or so-called safety reversal switch, which would otherwise cause an unintended reversal of the door.
Those skilled in the art will further appreciate the features and advantages of the door operator control system and method of operation as well as other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.


A capacitive-coupled level shifter includes: an input having a positive input terminal and a negative input terminal, the input configured to receive a modulated signal in a first voltage domain; a comparator circuit configured to shift the modulated signal to a second voltage domain higher than the first voltage domain; and a capacitive divider circuit comprising a first capacitive divider branch coupling the positive input terminal of the input to a positive input terminal of the comparator circuit and a second capacitive divider branch coupling the negative input terminal of the input to a negative input terminal of the comparator circuit. The first capacitive divider branch and the second capacitive divider branch are symmetric so as to cancel out a common mode voltage of the modulated signal. A level shifter system which includes the capacitive-coupled level shifter is also described.

Level shifters are used in applications where there is a need to interface between different voltage domains. Level shifters can be full-swing or floating, which can be distinguished by whether the voltage domains share a common ground potential. Floating level shifters are used to shift the potential of control signals from circuits powered by low voltage power rails to the potential of circuits with floating power and ground rails. Floating level shifters are often used in gate drivers to drive power output stages in applications such as DC-DC converters, biomedical transducer drivers, Class-D audio amplifiers, MEMS, LCD drivers, high voltage charge pumps, switched-capacitor supplies, etc.
While the gate driver typically is exposed to relatively low voltages, the level shifter and possibly other components such as a bootstrap switch or diode must use high-voltage components, i.e., components which can withstand the whole input voltage range. If the high voltage range is higher than the maximum allowed voltage for the single component but still within the technology capability, cascoding approaches can also be used.
There are several ways to implement a high voltage level shifter such as cascading a high voltage device, transformer based level shifting and capacitance based level shifting. The cascoding approach tends to be slower due to the stacking of devices which typically are high voltage and therefore consume layout area, degrade (speed) performance and require accurate parasitic modelling and extraction. For high speed gate driver applications such as full-bridge, half-bridge, non-isolated buck topologies, etc. where high common mode rejection is crucial to ensure a reliable output signal, the main advantage of transformer and capacitive based level shifting solutions is that they are dynamically driven. Since inductors and capacitors block any DC component of the signal, the control signal is transformed into a sequence of pulses, either single-ended or differential, which drive the transformer or capacitor. A static control input signal is therefore translated into a continuous sequence of pulses which refresh the stage of the gate driver in order to prevent false triggering due to noise. The repetition rate is defined by application conditions like switching frequency and duty cycle and may translate in sub-nanosecond requirements. This in turn implies high current consumption.
Thus, there is a need for an improved level shifter design.

Capacitive-coupled level shifter and related system


A method is disclosed for forming a paper web having a low tensile ratio. The method includes the steps of ejecting stock substantially horizontally from a headbox, and receiving the rejected stock onto a substantially horizontally disposed looped first wire, moving at substantially the same speed and the same direction as the ejected stock. The arrangement is such that a first portion of water is removed from the ejected stock downwardly through the first wire during passage of the ejected stock through an initial dewatering zone. The partially dewatered stock is sandwiched between the first wire and a looped second wire, the wires defining therebetween a secondary dewatering zone for further dewatering the ejected stock. A second and third portion of water are removed downwardly and upwardly, respectively, through the first and second wires during movement of the ejected stock past a curved shoe. The curvature of the secondary dewatering zone is reversed such that the wires extend around a curved inverted box connected to a source of partial vacuum, so that a fourth portion of water is removed upwardly through the second wire into the curved box. The arrangement is such that a gradual dewatering of the ejected stock is accomplished during passage of the stock through the initial and secondary dewatering zones, thereby inhibiting removal of fines from the ejected stock and minimizing the tensile ratio of the resultant web.

1. FIELD OF THE INVENTION
The present invention relates to a method of forming a paper web having a low tensile ratio. More particularly, the present invention relates to a method of forming a paper web in which a gradual dewatering of the ejected stock is accomplished, thereby inhibiting removal of fines from the ejected stock and minimizing the tensile ratio of the resultant web.
2. INFORMATION DISCLOSURE STATEMENT
During the manufacture of a web of paper, many factors interact in order to impart particular characteristics to the resultant web.
For example, when stock is ejected from a headbox onto a moving fourdrinier wire, the ratio of the velocity of the ejected stock to the velocity of the moving fourdrinier wire has an affect on the resultant web.
For certain paper grades, particularly for fine paper, the tensile strength of a web in a machine direction should be as close as possible to the tensile strength of the web in the cross-machine direction.
In the papermaking art, such ratio of the aforementioned tensile strength in the machine direction to the cross-machine direction is known as the "tensile ratio".
Particularly during the manufacture of envelopes and the like, it is desirable that the tensile ratio be as near as possible to unity, so that during the paper converting operation the sheet of paper responds equally regardless of the direction in which the sheet is folded.
The Horizontal Bel Baie forming machine taught in U.S. patent application 07/127,525, now U.S. Pat. No. 4,894,120, assigned to Beloit Corporation characteristically has a high drainage capacity and includes the advantage of fines retention within the ejected stock. Nevertheless, the Horizontal Bel Baie typically does not form a web having a tensile ratio less than two, regardless of the aforementioned jet-to-wire ratio. Horizontal Bel Baie is a trademark of Beloit Corporation.
The present invention overcomes the aforementioned problem of manufacturing a web having a relatively low tensile ratio by incorporating the features of the Horizontal Bel Baie and a curved inverted vacuum box of a twin wire Bel Bond machine, together with an initial single wire dewatering zone.
Therefore, it is a primary object of the present invention to provide a method of forming a paper web having a low tensile ratio, the method providing a significant and nonobvious contribution to the art of papermaking.
Another object of the present invention is the provision of a method of making a paper web having a low tensile ratio while maintaining fines retention.
Other objects and advantages of the present invention will be apparent to those skilled in the art by a consideration of the detailed description contained hereinafter taken in conjunction with the annexed drawings.


A load beam for an aerial vehicle comprises an elongate beam with a radial slot and a lug extending from the radial slot. A hook is pivotably connected to the lug. There is a first arm pivotably connected to the beam and a second arm pivotably connected to the beam. The first arm may be pivotably connected to a first mount and the second arm may be pivotably connected to a second mount. A pivot axis of the first arm relative to the elongate beam may be substantially parallel to a pivot axis of the first arm relative to the first mount. A pivot axis of the second arm relative to the elongate beam may substantially parallel to a pivot axis of the second arm relative to the second mount.

Field of the Invention
The present invention relates to a load beam, and in particular, to a belly-mounted load beam for an aerial vehicle.
Description of the Related Art
U.S. Pat. No. 8,888,048, which issued on Nov. 18, 2014 to Figoureux et al., discloses a fastener device provided with attachment means for attaching an external load and with fastener means for fastening the attachment means to a load-carrier structure of an aircraft. The fastener means are provided with a support beam and anchor means for anchoring the support beam. A first mechanical coupling connects the support beam to the anchor means so as to enable the support beam to pivot about a first pivot axis. In addition, coupling means are hinged to the support beam so as to make pivoting possible about a second pivot axis. The attachment means are hinged to the coupling means to make pivoting possible about a third pivot axis. The fastener device also includes automatic folding means.

Belly-mounted load beam for an aerial vehicle


A medical macromolecular microsphere adsorbent for a blood perfusion apparatus and a preparation method thereof are provided. The polystyrene-divinylbenzene microspheres are graded by different pore sizes and specific surface areas, medically purified, and grafted by a bioactivity-controlled grafting technology. In the microsphere adsorbent, the volume ratio of microspheres with pore sizes of 1-10 μm, 10-100 μm and 100 μm is 1:(1-10):(1-20), the content of residual monomers in the microsphere has O.D190-400 nm≤0.03. The microsphere adsorbent not only can adsorb harmful micromolecules in blood but also can effectively adsorb harmful medium-molecules and macromolecules in blood, thereby meeting clinical application demands.

A blood purification technology is a novel medical technology that has been developed on the basis of treatment of chronic renal function failure in the late 20th century. At present, there are about 2000 millions of patients needing blood purification all over the world, and in China, there are about 300 millions of patients. As treatment cost of maintaining blood purification is expensive, only 10% of patients can receive treatment in China at present. Thus, research and development of this technology have a huge potential.
A polystyrene-divinylbenzene microsphere, as the most commonly used medical macromolecular microsphere adsorbent in a blood perfusion apparatus, can adsorb medium-molecular β2 microglobulin in blood to a certain extent. However, the present polystyrene-divinylbenzene microsphere adsorbent used for the blood perfusion apparatus still has the following defects. First, grading design is not performed on pore size, which leads a fact that major adsorption substances are micromolecular substances such as creatinine and pentobarbital which are easy to remove via dialysis, and medium-molecules and macromolecules are difficult to remove. Second, at present, residues of strong irritant chemical substances chloromethyl ether and nitrobenzene are easily caused when neutral macroporous polystyrene-divinylbenzene microspheres are activated in China, so as to bring a great potential safety hazard to health of a patient. Then, blood compatibility of the adsorbent is poor, so red blood cells, leukocytes, blood platelets and the like are destroyed if the adsorbent directly contacts with blood. Thus, how to improve a medical macromolecular microsphere adsorbent is an important research direction of a blood purification technology.

Medical macromolecular microsphere adsorbent for a blood perfusion apparatus and a preparation method thereof


Systems and methods for indexing information and for performing searches are disclosed. In these systems and methods information is “ingested” into the system by clustering the information using a clustering algorithm such as k-means or k-medoids clustering. During the clustering process, a hybrid distance measurement is used that allows the systems and methods to determine similarity across a number of different types of information. Once the information is clustered, it is stored and “mirrored” both in a structured (e.g., relational) data repository and in an unstructured data repository. Methods according to the invention allow the retrieval of both direct search results and search results including related concepts. After clustered information is stored, future searches can be performed by searching the stored results in whichever data repository is most appropriate for the context.

1. Field of the Invention
The invention relates to computer-based searching, information retrieval, indexing, and storage.
2. Description of Related Art
Decades ago, large amounts of data were stored in a variety of different formats, depending on the application programs that were intended to access the data, the data types, and the preferences of the programmers who created the programs. In 1970, E. F. Codd, working at the IBM Research Laboratory, wrote a seminal paper, "A Relational Model of Data for Large Shared Data Banks," Communications of the ACM 13:6 (June 1970) proposing a new, relational way of storing large amounts of data. (That paper is incorporated by reference in its entirety.) Codd suggested that the formats in which data was stored should be independent of particular application programs and consistent across different types of programs. The relational database was born.
In a relational database, data is stored in so-called "tables," with certain fields in each table acting as searchable index fields and allowing a searcher to "relate" the information in one table with the information in another table. For example, assume that one table, "USERS" identifies users of a shared computing system and contains fields including first name, last name, gender, age, and identification number. Another table in the same database, "USAGE," contains information on users' use of a resource by identification number, including the fields identification number and usage amount. In that case, the "identification number" field links and provides a relationship between the two tables, such that an interested person could, for example, easily query the database for the names of all users whose usage exceeds a desired threshold, in which case the set of results would include selectively concatenated information from both tables.
Over the years, the use of relational databases in all sectors of industry exploded. Structured Query Language (SQL) evolved to allow database users to make very sophisticated queries of relational databases; essentially, the SQL language acts as an interface to most modern relational databases. Oracle, Inc. was one of the first and most prominent purveyors of enterprise-grade relational database systems, although many competitors emerged. As the Internet age dawned in the 1990s, relational databases became ubiquitous and open-source (i.e., user developed, readily shared, and typically low cost) relational database programs, like MySQL, emerged alongside offerings by major corporations, with the SQL language itself becoming more and more standardized. Ultimately, SQL databases have been used to handle the back-end processing for most major websites, and continue to be popular solutions.
The advantages of relational databases in general and SQL databases in particular are well documented in the literature. As Codd described, they are independent of the particular application programs that create and access them. The structure of the databases typically provides for relatively fast searching, and their ubiquity makes them easier to create and maintain and provides a variety of software options in the marketplace. Moreover, with recent relational database software, the tables defined in relational databases can often store not only textual data, but other forms of data, including various image, audio, and video files.
As the Internet has grown to maturity, the amount of data stored in and processed by computer systems has increased to the point where a single dataset may involve terabytes or even petabytes of information. Google, Inc., the Internet search company, has been one of the leaders in the science and mechanics of processing large data sets. Google's fundamental innovation in World Wide Web searching was to decide which pages were most relevant or authoritative by measuring how many other pages "linked" to them. By that algorithm, pages that were linked to more frequently were considered to be more authoritative and were presented earlier in the list of search results under most circumstances.
In 2004, two Google engineers, Jeffrey Dean and Sanjay Ghemawat, published a paper entitled "MapReduce: Simplified Data Processing on Large Clusters" describing a generalized, two-step method for processing a large dataset. That paper is incorporated by reference in its entirety. In a first step, a "map" function parses a dataset to obtain a set of associated data values and a "reduce" function parses that distributed set to output a final value or set of values. As one example given in the paper, the map-reduce method may be used to count uniform resource locator (URL) access frequency associated with an Internet site. In that case, the map function would process a log of web page requests and output <URL, 1> each time the particular URL in question is found in the log. The corresponding "reduce" function would count the output of the "map" function and output the data <URL, total count>. The MapReduce paper provides significant guidance in how to distribute map and reduce operations across a number of networked machines to successfully parse very large datasets.
So-called "NoSQL" or "unstructured" databases have developed in parallel with MapReduce and other large dataset processing techniques. These databases deviate from the traditional relational databases that use SQL for an interface either by using an interface other than SQL (e.g., JavaScript, XML, etc.), or by not storing data in tables and thus deviating entirely from the relational database model. These databases may be particularly suited for handling large datasets and for facilitating particular large-scale MapReduce operations on stored data. However, their feature sets may not be as robust or as standardized as SQL-based relational databases.
While the tools for processing large datasets have improved, and techniques for distributing processing tasks over large numbers of networked computers are now well described and commonly used, current information processing techniques are still not very good at facilitating deeper understanding of the information that is processed, e.g., at automatically making connections not only between related points or pages in a dataset, but between related concepts reflected in the dataset.

Clustered information processing and searching with structured-unstructured database bridge


A manufacturing method for a thermoplastic aromatic polyester resin composition is disclosed having a step of blending: a thermoplastic aromatic polyester resin A; an alkali composition B containing a thermoplastic aromatic polyester resin a and an alkali compound b; and a carbodiimide compound C. The alkali composition B is preferably a composition in which an aqueous solution of the alkali compound b is melt-kneaded with the thermoplastic aromatic polyester resin a. The carbodiimide compound C preferably contains an aromatic carbodiimide compound. The alkali compound U content in the thermoplastic aromatic polyester resin composition is preferably 10 ppm by mass or more and 100 ppm by mass or less.

Thermoplastic aromatic polyester resins, represented by polybutylene terephthalate resins and polyethylene terephthalate resins, are excellent in various properties such as heat resistance, chemical resistance, electrical properties mechanical properties, and moldability. For this reason, thermoplastic aromatic polyester resin compositions are widely used, as engineering plastics, in electric/electronic device components, automotive components, and the like.
However, when exposed to a high-temperature and high-humidity environment for a long time, the properties of thermoplastic aromatic polyester resins sometimes decline due to hydrolysis. For this reason, an improvement in hydrolysis resistance is sought, in particular, in thermoplastic aromatic polyester resin compositions used in molded articles such as automotive components which are used in environments that readily become high-temperature and high-humidity. Techniques of using thermoplastic aromatic polyester resins having few terminal carboxyl groups and of blocking terminal carboxyl groups of thermoplastic aromatic polyester resins by adding an epoxy compound, a carbodiimide compound or the like are used as techniques for improving hydrolysis resistance in thermoplastic aromatic polyester resin compositions (Patent Documents 1 and 2).
Patent Document 1: JP 2004-075756 A
Patent Document 2: WO 2010/018662 A Pamphlet

Production method of thermoplastic aromatic polyester resin composition


In one embodiment, a modular dissolution-testing apparatus has a base unit adapted to hold and control operation of between one and eight dissolution-testing modules. The base unit has a programmable controller and a color touch screen for user interface with the controller and the modules. Each module includes a vessel for holding a solution of a dosage form dissolving in a solvent, an agitator apparatus for stirring the solution, and a motor to power—via a multi-motion assembly and a stirring shaft—stirring by, lifting of, and lowering of, the apparatus. Each module has a vessel heater and a temperature sensor, both communicatively connected to the controller for heating and regulating the temperature of the vessel contents. Each module is independently controllable by the controller, where control includes manually (by a user) or programmatically setting stirring speed, lifting and lowering apparatus, and starting and stopping stirring and heating.

1. Field of the Invention
The current invention relates to systems and methods for controlled motorized operations, and more specifically, but not exclusively, to systems and methods for centrally controlled modular and scalable motorized scientific instrumentation.
2. Description of the Related Art
Dissolution testing apparatuses are controlled motorized testing systems used to determine the dissolution rates of solutes, such as pharmaceutical pills—also known as solid oral dosage forms, in specific solvents and at specified temperatures. This type of testing procedure is used, for example, in quality assurance (QA) dissolution testing—so-called since it is used to determine aspects of pharmaceutical quality—and in research and development (R&D). In dissolution testing, a dosage form (e.g., pill, tablet, or capsule) is typically either (1) dropped into a solvent-containing vessel, where a paddle is used to stir the solution that results from the dissolution of the solute in the solvent or (2) placed in a cage-like basket which is lowered into the solvent and spun, thereby also stirring the resultant solution. A test method specifies various dissolution test parameters, such as the stirring apparatus (e.g., paddle or basket), stirring speed (e.g., in revolutions per minute (RPM)), and the solution temperature. Samples of the solution are pulled at specified intervals during the test method run. These samples are then tested to determine the extent of dissolution of the dosage form at the specified time intervals.
Conventional dissolution testing systems are made in the form of a unitary integrated apparatus comprising six, seven, or eight vessels and corresponding stirring apparatuses for holding and stirring corresponding solutions of solvent and solute. The multiple stirring apparatuses are typically powered by a single motor to which they are connected by, for example, belts or gear systems. Industry practice for QA dissolution testing is to run six identical tests simultaneously in order to provide sufficient data for standard statistical analysis of the data. In other words, conventional apparatuses have six vessels whose contents are (1) at the same temperature and (2) stirred at the same speed by the same kind of stirring apparatus. The seventh and/or eighth vessel in dissolution testing apparatuses that have seven or eight vessels are typically used to provide replacement solvent at the proper temperature to replace the solution removed from the first six vessels in sample pulls. The temperature of the solution in a vessel may be maintained by (1) placing the vessel in a temperature-controlled water bath or (2) using a heating jacket around the vessel, as in a bathless apparatus.

Centrally controlled modular motorized testing


Disclosed herein are a method of inhibiting hair growth, which comprises administering an inhibitor of elastase-like enzymes or a neutral endopeptidase inhibitor, and use of an inhibitor of elastase-like enzymes or a neutral endopeptidase inhibitor for the preparation of a hair-growth inhibitor.

1. Field of the Invention
The present invention relates to a method of inhibiting hair growth, and more particularly to a method of inhibiting hair growth, by which hair growth on the legs and arms, and the like can be effectively inhibited, and use of a specific enzyme inhibitor for the preparation of a hair-growth inhibitor.
2. Description of the Background Art
A biological function of the scalp hair and body hair is to protect important organs of the head, chest, limbs and the like. With the development of clothes and protecting means, however, the organ-protecting function carried by the body hair has come to be unimportant.
The scalp hair is generally desired to be thick. In recent years, however, the tendency to prefer having no hair on, particularly, limbs and the like has been strengthened from the viewpoint of an aesthetic appearance. Therefore, various methods for removing the body hair have been developed and used. Specific examples thereof include mechanical removing methods making use of a shaver, hair plucker or the like, methods of using a depilatory to depilate body hair out of its root, methods of using a hair remover to remove body hair by its chemical reaction, etc.
However, these methods for removing the body hair are accompanied by the physical or chemical irritation of the skin, and the lastingness of their removing effects on the body hair is limited even though there is some difference between the methods. Therefore, such a treatment for removing the body hair must be conducted again after a certain period of time. It is thus desired to lighten the removal treatment of the body hair.
International Application WO98/25580 published Jun. 18, 1998 discloses a method for reducing hair growth by inhibiting the activity of a matrix metalloproteinase in the skin. The present invention intends the same purpose, i.e., providing a method of inhibiting hair growth. However, the researchers of the present invention found that hair growth is deeply influenced by the activity of elastase-like enzymes. Thus, there is fundamental difference in the present invention from the prior art, which provides a novel method characterized by inhibition of the activity of elastase-like enzymes.
Accordingly, it is an object of the present invention to provide a method of inhibiting hair growth, by which the growth of body hair can be effectively inhibited to reduce the number of removal treatments of the body hair.
In view of the foregoing circumstances, the present inventors have carried out an extensive investigation. As a result, it has been quite surprisingly found that inhibitors of elastase-like enzymes which digest elastin known as a structural protein in the artery, tendon, skin or the like, and inhibitors of neutral endopeptidases that are enzymes which digest opioid peptides such as enkephalin, and neuropeptides such as substance P and bradykinin have an excellent inhibitory effect on hair growth, thus leading to completion of the present invention.
According to the present invention, there is thus provided a method of inhibiting hair growth, which comprises administering an inhibitor of elastase-like enzymes or a neutral endopeptidase inhibitor.
According to the present invention, there is also provided use of an inhibitor of elastase-like enzymes or a neutral endopeptidase inhibitor for the preparation of a hair-growth inhibitor.
According to the present invention, an excellent inhibitory effect on hair growth can be achieved, and hair-growth inhibitors high in safety for the human body can also be provided.


A display having pivot constraint function is disclosed in the present invention. The display includes a panel, a supporter, a pivot mechanism and a constraint mechanism. The pivot mechanism is disposed between a first bridging component of the panel and a second bridging component of the supporter. A rotation angle of the panel relative to the supporter can be adjusted via the pivot mechanism, and the constraint mechanism can constrain the rotation of the panel relative to the supporter. The constraint mechanism includes a body and a contacting portion. The body is movably disposed on the panel, and partly protrudes from a boundary of the panel. The contacting portion is connected to the body for simultaneously contacting the first bridging component and the second bridging component, so as to constrain rotation between the first bridging component and the second bridging component, and to fix a view angle of the panel.

1. Field of the Invention
The present invention relates to a display, and more particularly, to a display capable of constraining its pivot angle for easy adjustment and steady immovability.
2. Description of the Prior Art
With the advanced technology, the display of the electronic device trends a large-scaled for comfortable entertainment enjoyment. The display is disposed on the supporter via a pivot mechanism. The user can rotate the display according to a position of the electronic device, to adjust a pivot angle of the display relative to the supporter for a preferred view angle. The pivot mechanism utilizes friction to generate force for supporting the display, so as to fix the pivot angle of the display relative to the supporter. However, the display of the conventional electronic device has huge volume, and a weight of the display is heavy accordingly. In order to overcome the weight of the display with the huge volume, friction of the pivot mechanism is increased for supporting the large-scaled display. Then, the user exerts violent force to adjust the rotation of the display. Operation of the conventional electronic device is inconvenient.
In addition, the display is usually matched with the touch screen interface for better entertainment of the product. Torsional friction of the conventional pivot mechanism is increased to support the large-scaled display. When the user clicks the display, the conventional pivot mechanism is ineffective easily, and the display may shake or sway. A conventional solution utilizes a lock mechanism to constrain the rotation of the pivot mechanism, so as to overcome a drawback of insufficient supporting force. By the conventional solution, the user releases constraint of the lock mechanism, then manually pushes the display for adjusting its view angle, and finally relocks the lock mechanism to finish operation. The operation of the conventional solution is complicated, a releasing step and a relocking step are necessary during the rotation of the display. Therefore, design of a pivot constraint mechanism with easy structure and convenient operation is an important issue in the mechanical industry.

Display having pivot constraint function