A method and apparatus which corrects errors in a receive vector and a receiver. An essentially conventional method and apparatus are used to produce a polynomial representation of the receive vector, syndromes associated with the receive vector, and a Galios Field table. An inventive method and apparatus is used to generate an error location polynomial table and thus an error location polynomial which can then be used to locate and correct a maximum number of errors in the receive vector. The inventive method includes comparing previously generated entities in an error location polynomial table to one another to determine which of the previously generated entries should be used in generating a next entry to the error location polynomial table.

1. Field of the Invention
This invention relates to method and apparatus for generating an error correction code for correcting errors in data, and more particularly, a method and apparatus for generating an error location polynomial table used to locate errors in data which has been encoded using a Reed-Solomon error correction technique.
2. Description of Related Art
Data which is either stored or communicated is susceptible to errors. Errors corrupt the value of the data and thereby obscure the original value. Therefore, in situations in which the exact value of data is required to be reliably determined, a means must be provided by which the original value of the data can be determined after the data has been read from a storage device or after received by a device at the receiving end of a communication path.
One means for determining the original value of data which has been corrupted is commonly referred to as Reed-Solomon error detection and correction. Reed-Solomon error detection and correction requires that the data initially be encoded. Data is grouped into information symbols which form Reed-Solomon blocks. The universe of all possible symbols is referred to as the "finite field". For example, forward error correction (FEC) used in Cellular Digital Packet Data (CDPD) is performed by transmitting information encoded in Reed-Solomon blocks comprising 47 information symbols of 6 bits each followed by 16 parity symbols of 6 bits each.
In accordance with Reed-Solomon encoding, the finite field is "closed", meaning that the product or sum of any two symbols within the finite field is another symbol within the finite field. Reed-Solomon encoding schemes are characterized by the total number of symbols n in an RS block, where n=2.sup.m -1 and m is the number of bits in each symbol, and the total number of information symbols in each block is k. A Reed-Solomon code is typically referred to as RS(n, k). Accordingly, a Reed-Solomon code in which symbols have 6 bits, and thus a total number of symbols in a block is equal to 63, and a total number of information symbols in each block is equal to 47 is referred to as RS(63, 47). It is well known in the art that the number of errors that can theoretically be corrected in a RS(n, k) encoding is (n-k)/2=t. Accordingly, 8 errors can theoretically be corrected using an RS(63, 47) code having 2t=16 additional (i.e., "parity") symbols in each block of 63.
Once the information has been mapped into a transmit vector and the transmit vector has been either stored or transmitted, errors which occur in the transmit vector can be detected and corrected by generating an error location polynomial .sigma.(X). The value of the error location polynomial is determined by one of several well known algorithms. One of these algorithms is known as "Berlekamp's iterative algorithm".
In accordance with Berlekamp's iterative algorithm the first step is to find a first minimum-degree polynomial .sigma..sup.(1) (X) whose coefficients satisfy a first Newton's identity. It should be noted that the superscript "(1)" indicates that this is the first minimum degree polynomial, as opposed to the second, third polynomial, etc., as will become apparent below. Details regarding the nature of the Newton's identity are provided in Error Control Coding: Fundamentals and Applications, by Shu Lin and Daniel J. Costello, Jr. (Prentice-Hall, 1983) which is herein incorporated by reference. Lin and Costello disclose a method for generating the values .sigma..sup.(.mu.) (X) by generating a series of "syndrome" components using a well known algorithm. The syndrome components are then used to generate "discrepancies", d.sub..mu.. If d.sub..mu. =0, then the coefficients of .sigma..sup.(.mu.) (X) satisfy the (.mu.+1).sup.th Newton's identity. Therefore: EQU .sigma..sup.(.mu.-1) (X)=.sigma..sup.(.mu.)
The next step is to test whether the coefficients of .sigma..sup.(1) (X) satisfy a second Newton's identity. If the coefficients of .sigma..sup.(1) (X) satisfy the second Newton's identity (i.e., d.sup.1 =0), then the value of a second minimum-degree polynomial .sigma..sup.(2) (X) is equal to the value of the first minimum-degree polynomial .sigma..sup.(1) (X). However, if the second Newton's identity is not satisfied by the first minimum-degree polynomial .sigma..sup.(1) (X) (i.e., d.sup.1 not equal to 0), then a correction term is added to .sigma..sup.(1) (X) to form .sigma..sup.(2) (X), such that .sigma..sup.(2) (X) has minimum degree and its coefficients satisfy the first two Newton's identities. Therefore, at the end of the second step of iteration, a minimum-degree polynomial .sigma..sup.(2) (X) has been obtained whose coefficients satisfy the first two Newton's identities. The third step is to find a minimum-degree polynomial .sigma..sup.(3) (X) from .sigma..sup.(2) (X), such that the coefficients of .sigma..sup.(3) (X) satisfy the third Newton's identity. If the coefficients of .sigma..sup.(2) (X) satisfy the first three Newton's identities (i.e., d.sup.2 =0), then .rho..sup.(3) (X)=.sigma..sup.(2) (X). If not, then a correction term is added to .sigma..sup.(2) (X) to form .sigma..sup.(3) (X). Iterations continue until each minimum-degree polynomial through .sigma..sup.(2t) (X) has been generated. The polynomial .sigma..sup.(2t) (X) is equal to the error location polynomial .sigma.(X). The error location polynomial .sigma.(X) yields an error pattern e(X) which can be used to determine the location of the errors in a received polynomial r(X), if the number of errors in the received polynomial is no greater then t.
The syndrome components are generated using a well known algorithm disclosed by Lin and Costello. The syndrome components are then used to generate the discrepancies, d.sub..mu..
If d.sub..mu. is not equal to zero, (i.e., the coefficients of .sigma..sup.(.mu.) (X) do not satisfy the (.mu.+1).sup.th Newton's identity) then a correction term must be added to .sigma..sup.(.mu.) (X) to obtain .sigma..sup.(.mu.+1) (X). To determine the value of this correction term, each previously generated polynomial .sigma..sup.(.mu.) (X) must be analyzed to determine which polynomial .sigma..sup.(.rho.) (X) has the largest degree (i.e., the greatest exponent of X) and has a corresponding .sigma..sup.th discrepancy d.sub..rho. not equal to zero. The value .rho. identifies a previously completed row of values within the error location polynomial table.
One way to organize this process is to generate an error location polynomial table, such as Table 1, in which for each value of .mu. there is an associated minimum-degree polynomial .sigma..sup.(.mu.) (X), a .mu..sup.th discrepancy d.sub..mu., a value 1.sub..mu. equal to the degree of the polynomial .sigma..sup.(.mu.) (X), and a value .mu.-1.sub..mu..
TABLE 1 ______________________________________ .mu. .sigma..sup.(.mu.) (X) d.sub..mu. l.sub..mu. .mu. - l.sub..mu. ______________________________________ -1 1 1 0 -1 0 1 .alpha..sup.12 0 0 1 1 + .alpha..sup.12 X .alpha..sup.7 1 0 (take .rho. = -1) 2 1 + .alpha..sup.3 X 1 1 1 (take .rho. = 0) 3 1 + .alpha..sup.3 X + .alpha..sup.3 X.sup.2 .alpha..sup.7 2 1 (take .rho. = 0) 4 1 + .alpha..sup.4 X + .alpha..sup.12 X.sup.2 .alpha..sup.10 2 2 (take .rho. = 2) 5 1 + .alpha..sup.7 X + .alpha..sup.4 X.sup.2 + .alpha..sup.6 0.sup.3 2 (take .rho. = 3) 6 1 + .alpha..sup.7 X + .alpha..sup.4 X.sup.2 + .alpha..sup.6 X.sup.3 -- -- -- ______________________________________
The is generated by initializing the table with the values of the first two rows, as shown in Table 2.
TABLE 2 ______________________________________ .mu. .sigma..sup.(.mu.) (X) d.sub..mu. l.sub..mu. .mu. - l.sub..mu. ______________________________________ -1 1 1 0 -1 0 1 S.sub.1 0 0 2 3 4 5 6 ______________________________________
The values of Table 1 have been determined by assuming a triple-error correcting Reed-Solomon code RS(15, 9) with symbols from the Galios Field GF(2.sup.4). In addition, it is assumed that an all zeros vector is transmitted and a vector r=(0 0 0 .alpha..sup.7 0 0 .alpha..sup.3 0 0 0 0 0 .alpha..sup.4 0 0) is received having three errors. It should be noted that while there are considered to be only three errors, each of the three errors represents a change of state of more than one bit within the receive vector. For example, the 4-tuple representation of .alpha..sup.7 is 1101. Therefore, three bits have changed state between transmission and reception, resulting in one errored symbol.
The polynomial representation of the receive vector is r(X)=.alpha..sup.7 X.sup.3 +.alpha..sup.3 X.sup.6 +.alpha..sup.4 X.sup.12. The polynomial representation of the receive vector is formed as a sum of products of each power representation and X raised to a power, the power to which X is raised being equal to the location of the power representation within the receive polynomial. In the present example, the first product is .alpha..sup.7 X.sup.3 because the sum of the first three products are each equal to zero (i.e., 0.multidot.1+0.multidot.X+0.multidot.X.sup.2 =0). In the present case, since all zeros were transmitted, the polynomial r(X) has only three components, each of which represent an erroneous symbol and its location. Syndrome components are created from the polynomial r(X) as follows: EQU S.sub.1 =r(.alpha.)=.alpha..sup.10 +.alpha..sup.9 +.alpha.=.alpha..sup.12(EQ. 2) EQU S.sub.2 =r(.alpha..sup.2)=.alpha..sup.13 +1+.alpha..sup.13 =1(EQ. 3) EQU S.sub.3 =r(.alpha..sup.3)=.alpha.+.alpha..sup.6 +.alpha..sup.10 =.alpha..sup.14 (EQ. 4) EQU S.sub.4 =r(.alpha..sup.4)=.alpha..sup.4 +.alpha..sup.12 +.alpha..sup.7 =.alpha..sup.10 (EQ. 5) EQU S.sub.5 =r(.alpha..sup.5)=.alpha..sup.7 +.alpha..sup.3 +.alpha..sup.4 =0(EQ. 6) EQU S.sub.6 =r(.alpha..sup.6)=.alpha..sup.10 +.alpha..sup.9 +.alpha.=.alpha..sup.12 (EQ. 7)
It should be noted that multiplication of a base raised to a power (commonly referred to as a power representation) by a second power representation in a Galios Field is performed by adding the exponents of like bases using modulo n addition, where n is the size of the entire Galios Field (in this case, 16) (e.g., .alpha..sup.7 .alpha..sup.3 =.alpha..sup.10). Furthermore, addition of a first power representation to a second power representation in a Galios Field is performed by looking up the n-tuple representation associated with each power representation and exclusive ORing the n-tuple representations (e.g., .alpha..sup.7 +.alpha..sup.3 =.alpha..sup.4 ; where the 4-tuple representation of .alpha..sup.7 =1101, the 4-tuple representation of .alpha..sup.3 =0001, (1101 XOR 0001)=1100, and the power representation of 1100=.alpha..sup.4). Table 3 provides the power representation and associated 4-tuple representations for each symbol in a Galios Field GF(2.sup.4).
TABLE 3 ______________________________________ Power Representation 4-Tuple Representation ______________________________________ 0 0 0 0 0 1 1 0 0 0 .alpha..sup.1 0 1 0 0 .alpha..sup.2 0 0 1 0 .alpha..sup.3 0 0 0 1 .alpha..sup.4 1 1 0 0 .alpha..sup.5 0 1 1 0 .alpha..sup.6 0 0 1 1 .alpha..sup.7 1 1 0 1 .alpha..sup.8 1 0 1 0 .alpha..sup.9 0 1 0 1 .alpha..sup.10 1 1 1 0 .alpha..sup.11 0 1 1 1 .alpha..sup.12 1 1 1 1 .alpha..sup.13 1 0 1 1 .alpha..sup.14 1 0 0 1 ______________________________________
The syndrome components are then used to calculate discrepancy components d.sub..mu.. As can be seen from Table 2, d.sub.-1 is always equal to 1 and d.sub.0 is always equal to S.sub.1. In the present example, d.sub.0 =S.sub.1 =.alpha..sup.12. Generation of the discrepancy components will be discussed below.
In generating the values of Table 1 according to the Berlekamp iterative algorithm, the next step is to determine the value of .sigma..sup.2 (X). The value of .sigma..sup.(.mu.+1) (X) is calculated by applying the formula: EQU .sigma..sup.(.mu.+1) (X)=.sigma..sup.(.mu.) (X)+(d.sub..mu. /d.sub..rho.).multidot.X.sup.(.mu.-.rho.) .multidot..sigma..sup.(.mu.) (X)(EQ. 8)
where .rho. identifies a previously completed row of values within the error location polynomial table. However, it can be seen that if d.sub..mu. is equal to zero, then: EQU .sigma..sup.(.mu.+1) (X)=.sigma..sup.(.mu.) (X) (EQ. 9)
The value of .rho. is determined by selecting a row which has been completed prior to the .mu..sup.th row, which has both a discrepancy d.sub..rho. which is non-zero, and for which the value of .mu.-1.sub..mu. in the last column (i.e., the right-most column) in the row is greatest in relation to the values in the last column in each other row which was completed prior to the .mu..sup.th row and which has a non-zero discrepancy.
To calculate the value .sigma..sup.(.mu.+1) (X)=.sigma..sup.(1) (X) it should be noted that .mu.+1=1. Therefore .mu.=0, d.sub..mu. =d.sub.0 =S.sub.1 =.alpha..sup.12, and .sigma..sup.(0) (X)=1. Furthermore, since only the row in which the value in the first column is equal to -1 was completed prior to the .mu..sup.th row and has a discrepancy that is not equal to zero, .rho. should be set equal to -1.
By setting .rho.=-1, the values of d.sub..rho. and X.sup.(.mu.-.rho.) can be determined. The value of d.sub..rho. =d.sub.-1 =1. The value of X.sup.(.mu.-.rho.) =X.sup.(0-(-1)) =X. Therefore, the value of .sigma..sup.(1) (X) can be determined by applying equation EQ. 8 as follows: ##EQU1##
This value is then inserted into Table 2, as shown in Table 4.
TABLE 4 ______________________________________ .mu. .sigma..sup.(.mu.) (X) d.sub..mu. l.sub..mu. .mu. - l.sub..mu. ______________________________________ -1 1 1 0 -1 0 1 S.sub.1 0 0 1 1 + .alpha..sup.12 X 3 4 5 6 ______________________________________
Next, the value of d.sub..mu. is calculated for the next row (the row currently being filled in) by applying the following formula: EQU D.sub..mu. =S.sub..mu.+1 +.sigma..sub.1.sup.(.mu.) (X).multidot.S.sub..mu. +.sigma..sub.2.sup.(.mu.) (X).multidot.S.sub..mu.-1 . . . +.sigma..sub.1.sbsb..mu.+1.sup.(.mu.+1) (X).multidot.S.sub..mu.+1-1.mu.+1(EQ. 11)
Wherein .sigma..sub.a.sup.(b) (X) is the a.sup.th coefficient of .sigma..sup.(b) (X) and 1.sub..mu.+1 =1. The polynomial .sigma..sup.(1) (X) has a degree of 1. Accordingly, for the case in which .mu.=1, 1.sub..mu. =1. The other variables of equation EQ. 11 are: S.sub..mu.+1 =S.sub.2 =1, .sigma..sub.1.sup.(.mu.) (X)=.sigma..sub.1.sup.(1) (X)=.alpha..sup.12, S.sub..mu. =S.sub.1 =.alpha..sup.12. It can be seen that d.sub..mu. has only two components, since the degree of .sigma..sup..mu. (X) is one.
Therefore: EQU d.sub..mu. =1+.alpha..sup.12 =1+.alpha..sup.24 =1+.alpha..sup.9 -1 0 0 0 .sym.0 1 0 1=1 1 0 1=.alpha..sup.7 (EQ. 12)
The value .mu.-1.sub..mu. =0 for the .mu..sup.th row. Thus, each of the columns of the third row can be completed.
Next, the values of the fourth row are calculated. First, the value of .sigma..sup.(.mu.+1) (X) is determined, for .mu.=1. If the value of d.sub..mu. were equal to zero, then the value of .sigma..sup.(.mu.+1) (X) would be equal to .sigma..sup.(.mu.) (X). However, since the value of d.sub..mu. is not equal to 0, but rather is equal to d.sub.1 =.alpha..sup.7, a value must be determined for .rho. in order to determine the value of .sigma..sup.(.mu.+1) (X).
Accordingly, a row must be identified which is prior to the .mu..sup.th row and which has both a non-zero value for d.sub..mu. and the greatest value of .mu.-1.sub..mu.. The value presented in the first column from the left of the identified row is selected as the value for .rho.. In the present case in which .mu.=1, the second row (i.e., the row associated with .mu.=0) is selected, and .rho. is set equal to 0. Applying the appropriate formulas, the values shown in the third row are attained in the same manner as was described with respect to the second row.
Next, the values of the fourth row are calculated. The value of .mu. is set to 2. Since the value of d.sub..mu. is not zero, a value must be determined for .rho.. However, at this point in the algorithm, a problem arises in determining the value of .rho.. That is, the value to be selected for .rho. is ambiguous, since there are two rows which each meet the requirements for selection of the value of .rho.. That is, both the second row (.mu.=0) and the third row (.mu.=1) are prior to the .mu..sup.th row, have a value of d.sub..mu. which is non-zero, and have values of .mu.-1.sub..mu. that are zero, zero being the largest value of any row which occurs prior to the .mu..sup.th row. It should be clear that the values associated with the second and third rows are very different and will result in different values for .sigma..sup.(.mu.+1) (X). In fact, if the wrong value is selected for .rho., the error location polynomial that results cannot be used to accurately determine the location of errors in the receive polynomial.
Other such conditions which result in an ambiguity as to the value of .rho. arise which make it impossible for errors to be located and corrected. These ambiguities must be resolved in a manner which ensures that the proper value is selected for .rho., and thus that the proper row is selected when determining the value of .sigma..sup.(.mu.+1) (X) by applying equation EQ. 8 above. However, Lin and Costello do not provide any mechanism for resolving this ambiguity. Therefore, it is assumed that the particular row to be used is either selected arbitrarily or that the first row that satisfies the Lin and Costello criteria is selected.
Accordingly, it would be desirable to provide a method and apparatus which allows accurate selection of the value of .rho. in cases in which more than one row are equally qualified to be selected as the row to be used in calculating the values of additional entries in table, and thus yielding an error location polynomial that can be used to locate and correct t-1 errors effectively in an RS(n, k) code in which n-k=2t.

Method and apparatus for generating an error location polynomial table

Uniden San Diego Research and Development Center Inc.


An electrohydraulic unit for pressure control in automotive vehicle brake systems includes a housing, wherein channels and accommodating bores for inlet and outlet valves, pressure accumulator, pump, pump valves, pump drive and pressure fluid ports are incorporated, wherein accommodating bores for the inlet and outlet valves open vertically into a first housing plane, and accommodating bores for the pump and the suction channel of the pump are arranged in a second housing plane disposed in parallel to the first housing plane, and the suction channel is connected to an accommodating bore of the pressure accumulator which extends both in the area of the first and the second housing planes. Both the suction channel and the pressure channel are positioned on a joint axis in the second housing plane, and both the suction valve and the pressure valve are arranged in the second housing plane coaxially one behind the other in the area of the suction and pressure valves.

The present invention relates to an electrohydraulic unit for pressure control in automotive vehicle brake systems.
German Patent Application No. 42 34 013 discloses an electrohydraulic unit for pressure control in automotive vehicle brake systems, wherein channels and accommodating bores are incorporated in a block-shaped housing. Electromagnetically operable inlet and outlet valves, pressure accumulators, pump pistons with pump valves and noise damping chambers are inserted into the accommodating bores. The inlet valves and the outlet valves are arranged in two valve rows which are aligned in parallel to each other. The accommodating bore for the pump extends between the two valve rows for the inlet and outlet valves. Another accommodating bore fore a noise damping chamber extends from the outside laterally to the accommodating bores for the inlet and outlet valves. Arranged in parallel to this accommodating bore side by side are further accommodating bores for the pressure accumulators. The selected parallel arrangement of the accommodating bores for the pressure accumulators and the damping chamber limits the maximum diameters of the pressure accumulators and the noise damping chambers due to the limited edge length of the housing, with the result that the volume absorption of the accommodating bores may be essentially changed by the bore depths. Besides, the edge length of the housing is determined not only by the side-by-side arrangement of the accommodating bores for the damping chambers and the pressure accumulators chosen but significantly depends on the radial extension of the pump. In the present state of the art construction, both the suction and the pressure valves are disposed within the pump piston, with the result of a relatively large overall size of the pump piston.
Therefore, an object of the present invention is to improve an electrohydraulic unit of the generic type to such effect that, with little effort and structure, a compact-size housing can be provided which especially involves a simple manufacture and best possible positioning of the individual structural components.
According to the present invention, this object is achieved for an electrohydraulic unit of the above-mentioned type by positioning both the suction channel and the pressure channel on a joint axis in the second housing plane, with the suction channel accommodating the suction valve of the pump and the pressure channel accommodating the pressure valve of the pump.


An actuator mechanism for alternate action switching devices having at least two states includes a housing structure and an actuator member slidably engaged therewith. In order to move the switching device between states, the actuator member has a contoured surface that moves along and remains in constant sliding engagement with a correspondingly contoured surface on the housing. A biasing member urges the actuator surface into the housing surface throughout operation. This provides noiseless operation of the switching device.

Alternate action switches are toggle switches which can make alternate electrical connections upon actuation. These switches are used in, for example, automotive applications for functions such as headlight beam change and hazard warning lights.
Referring to FIG. 1A, a conventional alternate action switch 10 includes a two piece housing 12, a two state switching device 14, an actuator mechanism 16, and a user interface (not shown).
The housing 12 supports the components of the switch 10. When the pieces of the housing 12 are joined a chamber 20 and a bore 22 are formed. Each piece of the housing 12 has a hole 24 disposed therethrough. A translational axis TA extends through the center of the bore 22. An operational axis OA extends through the holes 24. The operational axis OA is perpendicular to the translational axis TA.
The switching device 14 is mounted within the chamber 20 of the housing 12, and has two states which are exclusively and alternately selectable. The switching device 14 includes a carrier 25, a contactor 26, a first terminal 27, a second terminal 28, and a third terminal 29.
The carrier includes an orientation axis X, a post 30, and a contact surface 32. The orientation axis X references the angular orientation of the carrier 25 and the contactor 26.
Referring to FIGS. 1A and 1B, the post 30 is centrally disposed through the carrier 25 and engages the holes 24 in the housing 12, so that the carrier 25 is rotatably mounted to the housing 12. The post 30 is aligned with the operational axis OA.
The contact surface 32 generally has a w-shape, with a peak P and two valleys V1, V2 joining at the peak P. Each state of the switching device 14 corresponds to one of the valleys V1 or V2 on the carrier 25.
The copper contactor 26 is fixedly coupled to the carrier 25 and includes two spaced protrusions 26a. The terminals 27, 28, and 29 are also copper and are mounted on the housing so that they can be engaged by the contactor 26. The first terminal 27 is positioned to the left of the axis OA. The second and third terminals 28 and 29 are aligned one above the other to the right of the axis OA.
The actuator mechanism 16 includes a housing structure 34, an actuator member 36, and a helical compression spring 38.
The housing structure 34 includes a housing cup 40 and a cap 42. The housing cup 40 is a tube shaped structure having a cylindrical cavity 44, an open end 46 as shown in FIG. 1A, an opposed end wall 48, and a plurality of retention holes 50.
The end wall 48 has an aperture 52 centrally disposed therethrough. The end wall 48 further has an internal flat seating surface 54 which circumscribes the aperture 52. The holes 50 are circumferentially spaced adjacent the open end 46.
The actuator member 36 includes a torus shaped actuator base 56, and an actuator arm 58 extending from the base 56. The base 56 has two flat surfaces. The arm 58 has a center axis C which extends along the arm lengthwise. The actuator member 36 is disposed in the housing cup 40. The arm 58 extends through the aperture 52, and the base 56 rests against the seating surface 54. The helical compression spring 38 rests on the base 56.
The cap 42 includes a top 60 and a cylindrically shaped body 62 extending from the top 60, so that the cap 42 is generally T-shaped.
The cap 42 is disposed on the housing cup 40, so that the top 60 covers the housing cup 40, and the body 62 partially extends into the cavity 44. The protrusions 64 on the cap 42 extend into the holes 50 in the housing cup 40, so that the cap 42 is secured to the cup 40. The body 62 includes circumferentially spaced protrusions 64 and a reaction surface 66.
The reaction surface 66 physically limits how far the spring 38 and actuator member 36 can recede into the cavity 44. The spring 38 seats against the reaction surface 66, and exerts a force on the actuator base 56, urging the lower surface of the actuator base 56 into contact against the seating surface 54.
The housing cup 40 is inserted into the bore 22 of the housing 12. The actuator member is in a center or neutral position, which means the spring 38 has caused the center axis C of the actuator arm 58 to be aligned with the axis TA. The actuator member is in an off-center position when the axis C is not aligned with the axis TA.
The user interface (not shown) can be any means appropriate for effectuating the necessary translation of the actuator mechanism 16 to be discussed below. The effort applied by the user interface on the actuator mechanism is illustrated by the arrow UI. For example, the user interface can be a push button or a lever, which connects to the cap 42 in a conventional manner.
Referring to FIG. 1B, unactuated the actuator mechanism 16 has an initial position A1. The carrier 25 has an initial position C1, where peak P is to the right of the translational axis TA. In these initial positions the actuator mechanism 16 is in a retracted position, so that the actuator arm 58 is centered and spaced from the carrier 25.
Referring to FIGS. 1A and 1C, application of effort UI by the user interface (not shown) causes axial motion of the housing structure 34 along the axis TA, as represented by the arrow M. The actuator arm 58 engages the sloped contact surface 32 on the carrier 25, slides into the valley V1, and exerts a force on the carrier 25, via the valley V1. The carrier 25 and the contactor 26 rotate in the direction of the valley V1, as illustrated by the arrow R.. to a position C2. The peak P has rotated from right side of axis TA to the left side. The center axis C of the actuator arm 58 is not aligned with the translational axis, and the base 56 is spaced from the seating surface 54. This causes the switch to be in its first state, where the protrusions 26a of the contactor 26 are in contact with the first and third terminals 27 and 29. Thus, making a first electrical connection between the terminals 27 and 29, and other electrical components (not shown). Thus, the carrier 25 translates force provided by the actuator mechanism 16 along the axis TA to a force operating with respect to the axis OA.
When the user interface (not shown) is released, the housing structure 34 will retract along axis TA and return to its initial position A1 (as shown in FIG. 1D). The actuator member 36 will be urged by the spring 38 to return to the centered position. However, the carrier will remain in position C2.
Due to previous rotation of the carrier 25, the peak P is to the left side of the axis TA. Referring to FIG. 1E, a subsequent actuation by applying effort UI, will again cause the housing structure 34 to move along the axis TA. The actuator arm 58 engages the contact surface 32, slides into the valley V2, and exerts a force to rotate the carrier 25 and the contactor 26 in a direction R2 to position C1. The peak P is to the right of the translational axis TA. The center axis C of the actuator arm 58 is not aligned with the translational axis TA, and the base 56 is spaced from the seating surface 54. This causes the switch to be in its second state, where the protrusions 26a of the contactor 26 are in contact with the first and second terminals 27 and 28. Thus, making a second electrical connection between the terminals 27 and 28, and other electrical components (not shown).
Upon release of the user interface UI, the housing structure 34 will retract from the carrier 25 to its initial position A1, and the actuator member 36 will again return to the centered position. The carrier 25 will remain in the initial position C1.
Successive actuations will bring about alternate selection of the carrier and contactor's two positions C1 and C2 in the above described manner, consequently causing alternate engagement of the two states of the switching device 14 (as shown in FIG. 1A). The actuator member 36 will return to the initial and centered position after each switch actuation.
The conventional actuation mechanism 16 has undesirable results when used. Referring to FIGS. 1C and D, after each actuation, when the housing structure 34 retracts from the carrier 25 and the actuator member 36 returns to its centered position, there is an audible noise. This noise results from the actuator base 56 being forced by the spring 38 back against the seating surface 34.
As the level of noise generated is dependent upon the amount of force exerted by the spring 38, the noise could be lessened by using a less powerful spring. However, the spring 38 must meet minimum functional requirements such that it is strong enough to reseat the actuator base 56, and it is sturdy enough to withstand repetitive actuations associated with normal use. Use of a weaker spring would decrease the functional capability of the spring. A dampening lubricant can also be used to minimize noise. This switch is generally in an environment where its noisy operation will be readily discernible to the user, which may contribute to a lack of perceived quality by the customer.
Referring to FIG. 1B, the disc shape of the actuator base 56 allows for off-center seating when in the unactuated position. The disc must necessarily be of smaller dimensions than the cavity 44 which contains it, so as to allow unrestricted travel of the actuator base 56 during actuation. As a result, the small disk may return after actuation to an off-centered position.
Consequently, off-center seating results in a differential in required actuation efforts, where it will randomly require more or less effort on the user interface (not shown) for switch actuation. The effort required will be depend on the position of the actuator member 36 relative to the translational axis TA. As the actuator member 36 seats farther from the translational axis TA, the efforts required increase proportionately. This differential in actuation efforts is noticeable to the user and is an objectionable characteristic.
Assembly of the actuator mechanism 16 is also difficult. The design of the actuator mechanism requires that the actuator member 36 is oriented concentrically within the cavity 44, such that the actuator arm 58 aligns with the aperture 52 in the housing cup 40. Achieving the proper positioning is time consuming, and increases assembly cost.
Therefore what is needed in the art is an improved actuation mechanism, which emits minimal noise during operation, increases accuracy in center repositioning subsequent to actuation, and further, a simplified assembly process.

Actuator mechanism for an alternate action switch


Each of illumination portions 30a includes a bulb terminal VT electrically connected to a first electrical contact 31a of a bulb 31 and a battery wire B, a courtesy terminal CT which is electrically connected to a third electrical contact 32d of a switch 32 and a bypass wire P, and can be electrically connected to a second electrical contact 31b of the bulb 31 when an electrical contact member 32f of the switch 32 is brought into a position of FIG. 5, and a switch terminal ST electrically connected to a first electrical contact 32b of the switch 32 and a grounding wire G. The courtesy wire C and the bypass wire P can be electrically connected together by a mode-changing switch 33.

1. Field of the Invention
This invention relates to an illumination device in which a light-emitting operation mode can be switched or changed by operating a mode-changing switch.
2. Related Art
There are known various illumination devices, and for example, an illumination lamp is mounted on an interior wall of a ceiling of a room of a vehicle such as an automobile. There is known one example of such vehicle room illumination lamps which comprises a housing having an incandescent bulb (hereinafter referred to merely as "bulb") mounted therein, and a lens cover attached to this housing, and the bulb within the housing is turned on and off by operating a switch (see, for example, Unexamined Japanese Patent Publication 2002-79879)
Another example of such vehicle room illumination lamps is the type of illumination lamp (i.e., a so-called map lamp) including two illumination portions for respectively illuminating the driver's seat and the passenger's seat. In this vehicle room illumination lamp, bulbs of the two illumination portions are turned on respectively by operating switches of the two illumination portions.
In this vehicle room illumination lamp, a mode-changing switch is provided between the two illumination portions. By operating this mode-changing switch, the bulbs of the illumination portions are turned on and off in accordance with the opening and closing of a door of a vehicle. In recent years, such a vehicle room illumination lamp, thus having not only a light-emitting operation mode for merely turning on and off the bulbs of the two illumination portions but also a light-emitting operation mode (that is, a door opening/closing mode) for turning on and off the bulbs of the two illumination portions in accordance with the opening and closing of the vehicle door, has been used in many vehicles.
A three-conductor wire harness, having a battery wire, a grounding wire and a mode-changing courtesy wire, is used in a wiring circuit of the above second example of vehicle room illumination lamp. In each of the two illumination portions, a bulb terminal and a battery terminal are electrically connected to the battery wire and the grounding wire, respectively, and a courtesy terminal is connected to the courtesy wire. Further, in the mode-changing switch, two courtesy switch terminals are connected respectively to two electrically-separated end portions of that portion of the courtesy wire severed by stamping or the like. By switching this mode-changing switch, the separated wire portions of the courtesy wire can be electrically connected together and disconnected from each other.
In this circuit construction, the mode-changing switch for changing the light-emitting operation mode of the illumination portions by electrically connecting or disconnecting the separated wire portions of the courtesy wire need to be disposed closer to a DC power source for the wire harness. Therefore, the wire harness is connected to the mode-changing switch and the two illumination portions in this sequence from the power source.
In this wiring structure, the order of arrangement of the two illumination portions and the mode-changing switch on the housing (that is, one illumination portion, the mode-changing switch and the other illumination portion are arranged in this order on the housing) is different from the order of connection of the wire harness to the two illumination portions and the mode-changing switch. Therefore, the wire harness must be installed over a long distance in accordance with the arrangement of the illumination portions and mode-changing switch.
As a result, the installation of the wire harness as well as a holding structure of the housing becomes complicated, and therefore the assembling operation is cumbersome, and besides the wire harness has an increased length, so that the cost increases.
Furthermore, there is the type of vehicle equipped not only with such a vehicle room illumination lamp (that is, a so-called map lamp) but also with a vehicle room illumination lamp (that is, a so-called personal lamp) for illuminating a rear seat or others of the vehicle. In such an illumination lamp, a wiring circuit of the map lamp and a wiring circuit of the personal lamp are separate from each other, and therefore it is necessary to provide separate door opening/closing-mode courtesy wires, and therefore it is necessary to provide wire harnesses of different circuits. Similarly, two mode-changing switches need to be provided, so that the structure becomes complicated.
Thus, in the above vehicle room illumination lamp, the number and length of the wire harnesses increase, and also the number of the switches increases, and therefore the installation of the wire harnesses and the holding structure have become complicated, and the assembling operation has become cumbersome, and besides the cost has increased.


An assembly of trays in a divided wall column having an inner column wall, a dividing wall, and an interior space includes: a first tray having at least one radial downcomer adjacent the dividing wall and extending radially toward the inner column wall a first substantial distance, and a first liquid receiving area having a radial axis at a first angle to the dividing wall and extending radially toward the inner column wall a second substantial distance; and a second tray below the first tray, the second tray having at least one other downcomer having a radial axis at a second angle to the dividing wall and extending radially toward the inner column wall a third substantial distance, and at least one second liquid receiving area adjacent the dividing wall and extending radially toward the inner column wall a fourth substantial distance.

The present invention relates to liquid-vapor contact trays for use in divided wall exchange columns for heat and/or mass transfer processes. The invention has particular application in cryogenic air separation processes utilizing distillation, although it also may be used in other heat and/or mass transfer processes which use such trays.
As used herein, the term "column" (or "exchange column") means a distillation or fractionation column or zone, i.e., a column or zone where liquid and vapor phases are countercurrently contacted to effect separation of a fluid mixture, such as by contacting of the vapor and liquid phases on packing elements or on a series of vertically-spaced trays or plates mounted within the column.
Cryogenic separation of air is carried out by passing liquid and vapor in countercurrent contact through a distillation column. A vapor phase of the mixture ascends with an ever increasing concentration of the more volatile components (e.g., nitrogen) while a liquid phase of the mixture descends with an ever increasing concentration of the less volatile components (e.g., oxygen). Various packings or trays may be used to bring the liquid and gaseous phases of the mixture into contact to accomplish mass transfer between the phases.
A divided wall column is in principle a simplification of a system of thermally coupled distillation columns. In divided wall columns, a dividing wall is located in the interior space of the column. The dividing wall generally is vertical. Two different mass transfer separations may occur on either side of the dividing wall.
The exchange column usually contains some form of vapor-liquid contacting device which may be in the form of packing, such as random or structured packing, or in the form of a fractionation tray(s). A fractionation tray typically comprises a large flat area referred to as the decking or contacting deck of the tray plus means to deliver liquid to the tray from the next tray above and to remove liquid for passage to the next tray below.
The liquid being removed from the tray flows through a part of the tray referred to as a downcomer. The downcomer is a conduit for downward passing of liquid arranged in an opening in a panel of the contacting deck. In some downcomers, a part of the wall of the downcomer may extend above the panel and is called the outlet weir, and the part of the downcomer extending below the panel is called the downcomer apron. However, outlet weirs often are separate mechanical pieces and not necessarily an extension of the downcomer wall. In fact, trays may be designed without outlet weirs.
Vapor generated in the lower portion of the column passes upward through perforations in the decking, while the liquid flows downward from tray to tray countercurrent to the vapor. With a "crossflow tray" the liquid first enters upon a tray from the downcomer of the tray above. It then passes across the decking of the tray and finally exits through an outlet downcomer of the tray. U.S. Pat. No. 6,645,350 (Steacy) discloses one type of "crossflow tray."
During normal operation, liquid collected on a tray flows over a perforated panel of the deck where it is contacted with upwardly flowing vapor passing through the perforations. Then the liquid flows over the outlet weir into the downcomer and onto the receiving area of the perforated panel of the tray below, and so on. The downcomers of two adjacent trays are not placed directly above each other, but spaced apart in lateral direction (or staggered) in order to prevent liquid from falling directly into the downcomer of the lower tray.
One type of prior art tray uses a "racetrack" tray design, which has liquid flowing around an annular area with downcomers also placed radially. For example, U.S. Pat. No. 1,950,313 (Linde) discloses a "racetrack" tray.
It is desired to have an improved tray or trays for use in a divided wall exchange column which overcomes many of the difficulties and disadvantages of the prior art to provide better and more advantageous results.
It is further desired to have an improved cryogenic air separation plant having an improved tray or trays for use in a divided wall exchange column which overcomes many of the difficulties and disadvantages of the prior art to provide better and more advantageous results.

Radial-crossflow distillation trays for divided wall column applications


The invention disclosed herein describes a method for determining the suitability of a person for extended electrophysiologic testing for ventricular tachycardia comprising monitoring the heart of a person to detect an episode of nonsustained ventricular tachycardia, determining a cycle length variability (CLV) value, and comparing the CLV value to a predetermined threshold number, and making a positive suitability determination if the CLV value is at or below the predetermined threshold number.

1. Field of the Invention
The invention pertains to methods for using information obtained about the physiology of a person to make decisions regarding possible treatment of potentially life-threatening heart disorders, more particularly those disorders of the ventricular arrhythmatic type known to be associated with lethal sustained ventricular tachycardia.
2. Brief Description of the Prior Art
Cardiac arrhythmias are potentially life-threatening irregular heart rhythms usually occurring in the context of a diseased or damaged heart. The most serious cardiac arrhythmias are those originating within the large, lower heart chambers known as the ventricles. In a large proportion of patients who have ventricular arrhythmias, the risk of future sudden death is evaluated by performing a procedure known as an electrophysiologic study (EPS) in which the physician attempts to electrically "induce" an underlying rhythm disturbance known as sustained ventricular tachycardia (SVT). Ventricular tachycardia (VT) is a condition in which the ventricles, or lower chambers, of the heart experience a series of rapid abnormal contractions. If VT can be induced, the patient undergoes appropriate treatment to reduce his future risk of death. If no arrhythmia can be induced, such a risk is acceptably low and no further therapy is recommended.
One ventricular arrhythmia which is commonly seen is known as nonsustained ventricular tachycardia (i.e., ventricular tachycardia which lasts for only short periods) or NSVT. Since a significant number of patients who have NSVT go on to develop the more serious SVT, electrophysiologic testing is usually recommended for them. However, not all persons who have NSVT are subject to inducible arrhythmias and thus derive no benefit by undergoing the electrophysiologic testing.
Because electrophysiologic testing is potentially dangerous and requires expensive hospitalization for periods up to 3-4 weeks, it would be extremely useful to have a physiologic indicator which would help the physician determine which persons would benefit most from EP testing and would decrease the number of patients unnecessarily subjected to EP testing. Such an indicator would also give both the physician and patient the confidence that additional testing is appropriate when indicated.
In some patients with NSVT, a beat-to-beat variation in cycle length (where cycle length is defined as the time interval, measured in milliseconds (msec), between the R wave peaks of successive QRS wave complexes) can be observed to occur. In others, successive cycle lengths appear quite uniform. The degree of variation of cycle lengths during an episode of NSVT is referred to as cycle length variability. Examples of two electrocardiograms which exhibit variability in cycle length are shown in FIG. 1A and FIG. 1B.
Previous work by the inventor revealed that cycle length variability in episodes of NSVT is significantly lower in persons with inducible VT than in persons who experience NSVT but in whom VT is not inducible. K. P. Moulton, et al., "Cycle Length Variability in Nonsustained Ventricular Tachycardia: A Marker for Inducible Sustained Ventricular Tachycardia," PACE, 13:508 (1990). However, this work did not reveal a specific way that a cycle length variability value (hereinafter referred to as CLV) could be used to clearly delineate whether an individual exhibiting episodes of NSVT would be likely to be "inducible" and thus gain benefit from the extensive process of electrophysiologic testing.

Cycle length variability in nonsustained ventricular tachycardia

The Board of Regents of the University of Oklahoma


The overexpression of certain marker genes including Wnt5a has been found useful in the identification of more aggressive forms of malignant melanoma. Therefore, the overexpression of these genes in tumor samples of malignant melanoma may be useful in the diagnosis, profiling, and treatment of patients suffering from this disease. Inhibitors of Wnt5a activity may be useful in the treatment of aggressive forms of malignant melanoma. Inhibition of Wnt5a activity may be effected by any method including anti-sense therapy, gene therapy, and pharmaceutical intervention.

Cancer is the second leading cause of death in the United States after cardiovascular disease (Boring et al. Cancer J. Clin. 43:7, 1993; incorporated herein by reference). One in three Americans will develop cancer in his or her lifetime, and one of every four Americans will die of cancer. In order to better combat this deadly disease, efforts have recently focused on fine tuning the categorization of tumors; by categorizing cancers, physicians hope to better treat an individual's cancer by providing more effective treatments. Researchers and physicians have categorized cancers based on invasion, metastasis, gross pathology, microscopic pathology, imunohistochemical markers, and molecular markers. With the recent advances in gene chip technology, researchers are increasingly focusing on the categorization of tumors based on the expression of marker genes.
The most common human cancers are malignant neoplasms of the skin (Hall et al. J. Am. Acad. Dermatol. 40:35–42, 1999; Weyers et al. Cancer 86:288–299, 1999; each of which is incorporated herein by reference). The incidence of cutaneous melanoma is rising especially steeply, with minimal progress in non-surgical treatment of advanced disease (Byers et al. Hematol. Oncol. Clin. North Am. 12:717–735, 1998; McMasters et al Ann. Surg. Oncol. 6:467–475, 1999; each of which is incorporated herein by reference). Despite significant effort to identify independent predictors of melanoma outcome, no accepted histopathological, molecular, or immunohistochemical marker defines subsets of this neoplasm (Weyers et al. Cancer 86:288–299, 1999; Byers et al. Hematol. Oncol. Clin. North Am. 12:717–735, 1998; each of which is incorporated herein by reference). Accordingly, though melanoma is thought to present with different "taxonomic" forms, these are considered part of a continuous spectrum rather than discrete entities (Weyers et al Cancer 86:288–299, 1999; incorporated herein by reference). Improved characterization and understanding of this potentially deadly disease would be valuable.


A data driving apparatus for a liquid crystal display includes a plurality of digital-to-analog converter integrated circuits, a plurality of output buffer integrated circuits, at least two of the plurality of output buffer integrated circuits being commonly connected to each of the plurality of digital-to-analog converter integrated circuits, and a timing controller for controlling the plurality of digital-to-analog converter integrated circuits and the plurality of output buffer integrated circuits, wherein each of the plurality of digital-to-analog converter integrated circuits is mounted on a tape carrier package connected to a liquid crystal display panel, and each of the plurality of output buffer integrated circuits is mounted on the liquid crystal display panel.

1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a data driving apparatus and method for a liquid crystal display, wherein digital-to-analog converters are driven on a time division basis and integrated separately from output buffers, thereby reducing the number of digital-to-analog converter integrated circuits and data carrier packages.
2. Discussion of the Related Art
In general, a liquid crystal display (LCD) controls a light transmittance of a liquid crystal using an applied electric field to display an image (picture). The LCD includes a liquid crystal display panel having liquid crystal cells arranged in a matrix type, and a driving circuit for driving the liquid crystal display panel. The liquid crystal display panel includes gate lines and data lines arranged to cross each other, and each liquid crystal cell is positioned where the gate lines cross the data lines. The liquid crystal display panel is provided with a pixel electrode and a common electrode for applying an electric field to each of the liquid crystal cells. Each pixel electrode is connected to a corresponding one of the data lines via source and drain electrodes of a thin film transistor, which functions as a switching device. The gate electrode of the thin film transistor is connected to a corresponding one of the gate lines, thereby allowing a pixel voltage signal to be applied to the pixel electrodes for each corresponding data line.
The driving circuit includes a gate driver for driving the gate lines, a data driver for driving the data lines, and a common voltage generator for driving the common electrode. The gate driver sequentially applies a scanning signal to each of the gate lines in order to sequentially drive the liquid crystal cells on the liquid crystal display panel one gate line at a time. The data driver applies a data voltage signal to each of the data lines whenever the gate signal is applied to any one of the gate lines. The common voltage generator applies a common voltage signal to the common electrode. Accordingly, the LCD controls a light transmittance by application of an electric field between the pixel electrode and the common electrode in accordance with the data voltage signal for each liquid crystal cell, thereby displaying an image. The data driver and the gate driver are incorporated into a plurality of integrated circuits (IC's). The integrated data driver IC and gate driver IC are mounted in a tape carrier package (TCP) to be connected to the liquid crystal display panel by a tape automated bonding (TAB) system, or mounted in the liquid crystal display panel by a chip on glass (COG) system.
FIG. 1 schematically shows a data driving block of an LCD according to the conventional art. In FIG. 1, a data driving block includes data driving IC's 4 interconnected between a liquid crystal display panel 2 and a data printed circuit board (PCB) 8 via TCP's 6. The data PCB 8 receives various signals including control signals from a timing controller (not shown), data signals, and driving voltage signals from a power generator (not shown), thereby interfacing the various control signals to the data driving IC's 4. Each of the TCP's 6 are electrically interconnected between a data pad that is provided at an upper portion of the liquid crystal display panel 2 and an output pad that is provided at each data PCB 8. The data driving IC's 4 convert digital pixel data into analog pixel signals in order to apply the analog pixel signals to data lines on the liquid crystal display panel 2.
FIG. 2 is a detailed block diagram showing a configuration of the data driving integrated circuit in FIG. 1 according to the conventional art. In FIG. 2, each of the data driving IC's 4 includes a shift register part 14 for applying a sequential sampling signal, a latch part 16 for sequentially latching and simultaneously outputting a pixel data VD in response to the sampling signal, a digital-to-analog converter (DAC) 18 for converting the pixel data VD received from the latch part 16 into a pixel signal, and an output buffer part 26 for buffering and outputting the pixel signal received from the DAC 18. Furthermore, the data driving IC 4 includes a signal controller 10 for interfacing various control signals from a timing controller (not shown) and the pixel data VD, and a gamma voltage part 12 for supplying positive and negative gamma voltages required in the DAC 18. Each of the data driving IC's 4 drives an n-number of data lines D1 to Dn.
The signal controller 10 controls various control signals (i.e., SSP, SSC, SOE, REV and POL, etc.) and the pixel data VD to output the control signals and pixel data VD to various corresponding elements. The gamma voltage part 12 sub-divides several gamma reference voltages from a gamma reference voltage generator (not shown) for each gray level and outputs signals to the DAC 18.
The shift register part 14 includes an n-number of shift registers that sequentially shift a source start pulse SSP that is received from the signal controller 10 in response to a source sampling clock signal SSC, and output the source start pulse SSP as a sampling signal.
The latch part 16 sequentially samples the pixel data VD received from the signal controller 10 in response to the sampling signal received from the shift register part 14 to latch the pixel data VD. Accordingly, the latch part 16 comprises an n-number of latches for latching an n-number of pixel data VD, wherein each of the n-number of latches has a size corresponding to a bit number (i.e., 3 bits or 6 bits) of the pixel data VD. Specifically, a timing controller (not shown) simultaneously outputs the pixel data VD divided into even pixel data VDeven and odd pixel data VDodd via each transmission line, thereby reducing transmission frequency. Each of the even pixel data VDeven and the odd pixel data VDodd includes red (R), green (G) and blue (B) pixel data. Thus, the latch part 16 simultaneously latches the even pixel data VDeven and the odd pixel data VDodd received from the signal controller 10, i.e., 6 pixel data for each sampling signal. Subsequently, the latch part 16 simultaneously outputs an n-number of pixel data VD in response to a source output enable signal SOE received from the signal controller 10. The pixel data VD, which has a transited bit number that exceeds a reference value, is modulated to have a reduced transition bit number in order to minimize an electromagnetic interference (EMI) upon transmission from the timing controller. Accordingly, the latch part 16 restores the modulated pixel data VD to have a reduced transition bit number in response to a data inversion selecting signal REV, and then outputs the pixel data VD.
The DAC 18 simultaneously converts and outputs the pixel data VD from the latch part 16 into positive and negative pixel signals. Accordingly, the DAC 18 includes a positive (P) decoding part 20 and a negative (N) decoding part 22 that are commonly connected to the latch part 16, and a multiplexor (MUX) 24 for selecting output signals of the P decoding part 20 and the N decoding part 22.
The P decoding part includes an n-number of P decoders that convert an n-number of pixel data simultaneously inputted from the latch part 16 into positive pixel signals in response to positive gamma voltages received from the gamma voltage part 12. The N decoding part 22 includes an n-number of N decoders that convert an n-number of pixel data simultaneously inputted from the latch part 16 into negative pixel signals in response to negative gamma voltages received from the gamma voltage part 12. The multiplexor 24 responds to a polarity control signal POL received from the signal controller 10 in order to selectively output the positive pixel signals from the P decoding part 20 or the negative pixel signals from the N decoding part 22.
The output buffer part 26 includes an n-number of output buffers that comprise voltage followers that are connected in series to the n-number of data lines D1 to Dn. The output buffers buffer the pixel voltage signals received from the DAC 18, and apply the buffered pixel voltage signals to the n-number of data lines D1 to Dn.
Accordingly, each of the data driving IC's 4 according to the conventional art require an n-number of shift registers, an n-number of latches, and a 2n-number of decoders in order to drive the n-number of data lines D1 to Dn. As a result, the data driving IC's 4 according to the conventional art have a complex configuration, and hence a relatively high manufacturing cost.

Data driving apparatus and method for liquid crystal display


The invention relates to compositions, kits, and methods for detecting, characterizing, preventing, and treating prostate cancer. FKBP markers are provided, wherein changes in the levels of expression of one or more of the FKBP markers is correlated with the presence of prostate cancer.

Prostate cancer is the second most common cause of cancer related death and will kill an estimated 37,000 people this year alone. The prostate gland, which is found exclusively in male mammals, produces several regulatory peptides. The prostate gland comprises stroma and epithelium cells, the latter group consisting of columnar secretory cells and basal non-secretory cells. A proliferation of these basal cells, as well as stroma cells gives rise to benign prostatic hyperplasia (BPH) which is one common prostate disease. Another common prostate disease is prostatic adenocarcinoma (CaP), the most common of the fatal pathophysiological prostate cancers. Prostatic adenocarcinoma involves a malignant transformation of epithelial cells in the peripheral region of the prostate gland. Prostatic adenocarcinoma and benign prostatic hyperplasia are two common prostate diseases which have a high rate of incidence in the aging human male population. Approximately one out of every four males above the age of 55 suffers from a prostate disease of some form or another.
To date, various substances that are synthesized and secreted by normal, benign and cancerous prostates are used as tumor markers to gain an understanding of the pathogenesis of the various prostate diseases and in the diagnosis of prostate disease. The three predominant proteins or peptides secreted by a normal prostate gland are Prostatic Acid Phosphatase (PAP), Prostate Specific Antigen (PSA) and prostatic inhibin (PIP) also known as human seminal plasma inhibin (HSPI). Both PSA and PAP have been studied as tumour markers in the detection of prostate disease but since both exhibit elevated levels in prostates having benign prostatic hyperplasia (BPM) neither marker is specific and therefore are of limited use.
Despite the available knowledge, little is known about the genetic basis underlying the prostate cancer disease and the androgen-regulated genes that may be involved with its progression. Although androgens have been known to play a major role in the biology of prostate cancer. However, the full complexity of the hormonal regulation has not been completely covered and more androgen related processes are being elucidated. Many of these processes involve several molecules associated in prostate cancer that remain elusive. In addition, there may be several known molecules that have not yet been associated with the pathogenesis of the disease. Accordingly, a need exists for identifying unknown molecules that may be involved in prostate cancer and the genes encoding them. A need also exists for identifying known molecules that have not yet been implicated in the pathogenesis of prostate cancer, particularly those that can serve as targets for the diagnosis, prevention, and treatment of prostate cancer.

Expression analysis of FKBP54 in assessing prostate cancer therapy


A transgenic animal containing germ cells and somatic cells which contain a non-native recombinant gene which codes upon expression hexokinase capable of expressing hexokinase at significantly increased levels for study of the role of hexokinase in diabetes and other diseases. When these transgenic animals were exposed to a calmodulin stimulated model of diabetes increased levels of hexokinase activity were able to promote insulin secretion thereby reducing glucose levels in blood and transiently reduce the effects of diabetes.

Diabetes is a disease which effects many Americans. It is a disorder of carbohydrate metabolism characterized by hyperglycemia and glycosuria and resulting from inadequate production or utilization of insulin. The disease takes several different forms and is generally classified into two syndromes: Type I, or insulin-dependent diabetes mellitus (IDDM) and type II, or non-insulin-dependent diabetes mellitus (NIDDM). In Type I the patients secrete little or no insulin. In Type II the individual is able to produce insulin but for whatever reason the individual does not secrete enough insulin to control hyperglycemia. Type II is the most prevalent form of the disease and effects approximately 2-4% of individuals. Current treatment of diabetes Type II (NIDDM) involves constant maintenance of diet and often insulin therapy.
Ordinarily, after insulin is secreted by the xcex2 cells of the pancreas it is transported to the cells of the body where it binds to specific insulin receptors. The insulin then acts to promote glucose metabolism in the cell and to inhibit glucose production by the liver.
The basic cause for diabetes is still uncertain but the pathological defect involves failure of the xcex2 cells of the pancreas to secrete an adequate amount of insulin. In the absence of sufficient insulin, gluconeogenesis is stimulated, glycolysis is adversely affected and glucose uptake is reduced. All of these factors contribute to diabetic hyperglycemia.
Glucose is the primary regulator of insulin secretion. It is well established that glucose must be metabolized for insulin secretion to ensue. The rate of insulin secretion closely parallels its metabolic rate and inhibitors of glucose metabolism effectively block insulin secretion. In all cells glucose metabolism is initiated by hexokinase-catalyzed phosphorylation. Unique to the pancreatic xcex2 cell and the hepatocyte of the liver, this reaction is catalyzed by an unusual hexokinase isoform, hexokinase IV (commonly referred to as glucokinase due to its relative specificity for glucose as a substrate). Hexokinase IV has a Km for glucose in the physiological range of glucose levels, ≈10 mM. This is almost two orders of magnitude higher than any other mammalian hexokinase. Therefore, in vivo hexokinase IV-catalyzed phosphorylation is proportional to blood glucose levels, whereas phosphorylation by other hexokinases is saturated at physiological glucose levels. Hexokinase IV is also distinct from other hexokinases in that it is not allosterically inhibited by its product, glucose 6-phosphate (G6P). Due to the high Km of hexokinase IV and the absence of end-product inhibition, glucose phosphorylation in the xcex2 cell closely parallels circulating glucose concentrations. It has therefore been proposed that hexokinase IV functions as the glucose receptor or glucose sensor of the pancreatic xcex2 cell.
In non-insulin-dependent diabetes mellitus (NIDDM), there is a failure to secrete adequate amounts of insulin despite the fact that pancreatic islets retain significant levels of insulin. (Stefan, Y. et al. (1982) Diabetes 31,694-700.) The secretory deficit appears to be specific for glucose-induced secretion as other secretagogues retain normal efficacy. (Palmer, J. P. et al, (1976) J. Clin. Invest. 58,565-570). The hypothesis that hexokinase IV may serve as the xcex2-cell glucose sensor has taken on great clinical significance recently since it has been demonstrated that a nonsense mutation in only one allele of the hexokinase IV gene predisposes to some types of NIDDM. (Vionnet, N. et al (1992) Nature (London) 356,721-722.) As hexokinase IV is a monomeric enzyme, these results suggest that a simple 50% reduction in hexokinase IV activity due to mutational inactivation of one allele may lead to diabetes.
Thus it can be seen a need exists in the art for further study of the causes of diabetes which may lead to a potential cure, as well as a test of the hypothesis that hexokinase IV may serve as the glucose xcex2-cell sensor. It is an object of the present invention to provide a transgene which expresses a 2-fold increase in hexokinase activity for study of the role of hexokinase in insulin secretion and diabetes.
It is another object of the present invention to provide a method of decreasing diabetes by stimulating hexokinase activity and thereby increase insulin secretion for Type II diabetic patients.
It is yet another object of the present invention to provide an animal model for study of diabetes or other glucose regulatory mechanisms in which the animal model experiences a 2-fold increase in hexokinase activity which is specific to the xcex2 cell.
The present invention relates to construction of a transgene comprising the yeast hexokinase B gene (yeast hexokinase B like hexokinase IV is not allosterically inhibited by intracellular levels of G6P) operatively linked to an insulin promoter. The transgene, when inserted into mice resulted in a 2-fold increase in hexokinase activity. The increase was found to significantly augment glucose stimulated insulin secretion of isolated pancreatic islets, to increase serum insulin levels in vivo, and to lower blood glucose levels of transgenic animals by 20-50% below control levels.
The transgene of the present invention may be introduced into an animal model for study of the disease, or may be used for direct manipulation of pancreatic xcex2 cells for possible treatment for diabetes.

Pancreatic xcex2 cell hexokinase transgene

University of North Dakota Medical Education Research Foundation


An integrated safety and communication system for attachment to a standard type of firefighter's face mask includes a command post tracking and accountability monitor, and a mask attachment having means for transmitting the amplified voice of the wearer to anybody within its audible range, and to enable communications with the command post including identification, location, vital signs such as pulse and respiratory rate, vicinity temperature, hydrocarbon monitoring and alarm signal if the wearer becomes motionless for a predetermined time period.

Fireground personnel accountability is a vital safety issue for the fire service. In the future, the fire service will see increased pressure from litigation, other court action, and regulation and standard setting bodies to improve the manner in which we account for our firefighters operating in life-threatening work environments.
Why the need for improved accountability? A 10-year study of firefighter deaths conducted by the National Fire Protection Association (NFPA) found that 34 of 134 firefighter Fireground deaths not related to heart attacks reflected a failure to account for personnel. That's a 25 percent fatality figure related to accountability. That should not be happening.
Any firefighter suspected to be missing must be assumed lost in the hazard zone and immediately reported to command. Simultaneously with a roll call, command must initiate a search-and-rescue effort, starting at the last reported location of the missing firefighter. An additional alarm should be struck to obtain additional resources. There can be no hesitation since the window of survivability for the lost firefighter is very narrow.
An accurate means of coordinating and documenting search efforts must be developed (e.g., grids searched, ways to avoid duplication of or missing grids). Very strict control over firefighting personnel must be maintained during rescue efforts to control "panic actions" and freelancing by crews.
Communication is a critical component of effective fireground command. In the investigation of the operations at any incident, indicate that communications problems exist from the outset and continued for most of the duration of an incident.
Specific two-way communications from a stationary incident commander to interior operating officers, sector officers, and any other ICS (Incident Command System) positions must be accomplished and completed.
Communications between firefighters and company officers by visual and audible means also must exist at the intercompany level. Good communication is the foundation of a fireground accountability/safety system.
In recent years a great deal of interest has been shown in the provision of a means to enable unmuffled voice communication from a protective firefighters mask and the like. Some illustrative examples are shown in the patents noted below.
U.S. Pat. No. 4,508,936 issued Apr. 2, 1985 to Robert Ingall, shows and describes a communication system that utilizes an amplifier/speaker unit (32) that is mounted on the firefighter's waist-belt and is connected to the face mask via a cable (30).
The system appears to use an induction method of transmission which is relatively sumptuous of battery energy and can either cause interference with and/or receive interference from external transmission signals. Another problem with this device is the high possibility of getting the cable (30) caught on something like a nail or other projecting object resulting in possible loss of communication and/or dislodging the face mask of the wearer while in a hazardous air (fire) environment.
U.S. Pat. No. 3,180,333 issued Apr. 27, 1965 to R. D. Lewis appears to show and describe a gas mask device that uses a signal transmitting line (50) mounted to the belt of the wearer. The amplifier unit is molded into/for a specific mask and therefore has limited use, which increases its relative repair/replacement costs. The amplifier and microphone appear to be hard wired through the mask by an adaptor which therefore results in a breach of the mask wall. The breach may result in a loss of integrity of the mask. This device also has the inherent problems noted above with regard to the Ingall's patent.
Other prior art patents of interest include U.S. Pat. No. 3,314,424 issued Nov. 14, 1962 to M. Berman; U.S. Pat. No. 2,953,129 issued Sep. 20, 1960 to A. Bloom et al; U.S. Pat. No. 2,997,550 issued Aug. 22, 1961 to A. D. Trader; U.S. Pat. No. 3,540,442 issued Nov. 17, 1970 to Robert L. Holloway; and U.S. Pat. No. 2,950,360 issued Aug. 23, 1960 to R. K. Duncan.; U.S. Pat. No. 4,491,699 issued Jan. 1, 1985 to Martin J. Walker; and U.S. Pat. No. 5,060,308 issued Oct. 22, 1991 to John S. Bieback.
These patents are mentioned as being representative of the prior art and other pertinent references may exist. None of the above cited patents are deemed to affect the patentability of the present claimed invention. The present invention involves a novel combination of features and components combined in such a way as to afford a very efficient, cost effective, relatively more reliable, easier to use solution to the difficulties and problems encountered with the prior art.
The present invention resides in part on the use of signal coupling between the microphone and the speaker-amplifier.
The mounting of the microphone unit on the mask and the speaker-amplifier on the outside of the mask. The obviating of any need for connecting cables. The ease and inter-changability of the microphone and the speaker amplifier for quick and simple repair. The ease of replacing batteries. The relative ease of use obviating the need for connecting cables and mounting speakers to belts and the like.
The monitoring of the identity of each activated unit by transmitting a signal to a command post. The location of each activated unit being monitored at the command post. The selective monitoring and recording of communications between the command post and site involved firefighters, i.e., activated units, and/or the communications between activated units. The automatic monitoring and alarm of hazardous conditions such as excessive temperature and hydrocarbons at the units location. The automatic monitoring of the firefighters vital signs and activity level.

Firefighters integrated communication and safety system


A cabriolet motor vehicle is provided, which comprises a roof constructed from at least two roof segments, which may be brought into an open position, rear roof columns stiffened by an upper roof cross member (“Targa part”), and a rollbar (“Targa bar”) situated in the area between a front frame and the Targa part, and is distinguished in that the at least two roof segments are stackable using a movement mechanism into a roof segment stack situated between the Targa bar and the target part, and the roof segment stack is pivotable into the passenger compartment using at least one connecting rod attached to the upper roof cross member of the Targa part.

In the automobile industry, motor vehicles for use predominantly as transport vehicles like a pickup have been constructed until now having an open cargo area, by which the usability of the cargo area is restricted during bad weather, however. In addition, pickups are unsuitable for use solely as passenger automobiles.
Furthermore, constructing small SUVs as passenger automobiles and as utility vehicles having a closed or open cargo area like a pickup is known. Such SUVs are provided with a removable hardtop or cover mechanisms similar to a cabriolet in combination with plug-ins or fixed elements to expose an open cargo area and simultaneously offer the possibility of a closed cargo area. However, the mounting of elements of this type has proven to be time-consuming and work-intensive in practice, because of which such vehicles are impractical for only occasional transport. Furthermore, up to this point there has been no screening of the cargo area from the passenger compartment, so that exhaust gases and cold outside air may reach the passenger compartment. In view of the foregoing, it is at least one object to provide an open motor vehicle (cabriolet) that may be used on one hand predominantly as a passenger automobile and on the other hand predominantly as a utility vehicle, in particular like a pickup having an open or closed cargo area. Furthermore, other objects, desirable features and characteristics of the present invention will become apparent from the subsequent summary detailed description and appended claims, taken in conjunction with the accompanying drawings and this background.


A graphical interaction and authoring system is provided that combines textual and graphical information to display hierarchical information via an interactive visual mechanism for the composition and manipulation of syntactic structures, enabling business users to view, operate, and compose information in a way that not only graphically preserves the structure of the syntax, but also maintains the relationship of the expression. The system provides a way for the users to interact with it dynamically and effectively.

The use of business rules and policies to externalize business and operational logic from an application is an important concept and approach to building large business applications and to new areas such as self-managing systems or autonomic computing systems. Business rules and policies are statements that are intended to be readable and modifiable by non-technical users and executable by an underlying mechanism such as a rule engine or a Java Virtual Machine (JVM), allowing application logic to be authored and modified external to the application.
One of the key aspects of using these business rules or policies is the ability to specify a priority for each of the rules in a set of business rules. A business rule set is a collection of rules selected and arranged to achieve a desired goal. Assigning a priority to each rule contained in the rule set controls the sequence of execution of rules in the rule set. Typically, priorities are initially established and assigned by a rule author; however, priority of the rules can be subsequently modified in accordance with application specific parameters, i.e. different situations and execution environments.
In a basic method of specifying the priority of each rule in a rule set, the rule author attaches a number, for example an integer value, to each rule that indicates the priority of that rule relative to the other rules in the rule set. The relationship between the attached number and the priority can be inverse such that the higher the number the lower the priority, or proportional such that the lower the number the lower the priority.
Priorities have been assigned to rules that are triggered based upon the occurrence of specified events or the value of specified parameters. Since the occurrence of a single event can trigger more than one rule, priorities are established among the rules to determine which of the rules are applied first. Therefore, even if multiple rules are triggered based upon the occurrence of an event, only the triggered rule with the highest established priority will be applied. For example, a first rule in a rule set, assigned a priority value of 2, offers a discount of 10% to customers that spend more then $100.00. The second rule, assigned a priority value of 1, offers a discount of 20% if the customer buys at least 10 items, and a third rule, assigned a priority value of 3, offers a discount of 25% if the customer buys at least 10 items in the month of December. The priority values indicate that the second rule is applied first followed by the first rule and then the third rule.
Priority has also been provided by arranging the rules in an ordered list by the desired order of execution. For example, a first rule offers a discount of 10% if the customer spends more than $100.00, and a second rule offers a discount of 20% if the customer buys at least 10 items. A third rule offers a discount of 25% during the month of December if the customer buys at 10 least items. Using this approach, the rule author is specifying that rule 1 is always executed first followed by rule 2 and then rule 3.
In addition to priority, additional constraints have been applied to each rule. The rule author can prescribe time periods for the enabling or disabling of the execution of a given rule. For example, the first rule wherein the customer is offered a 10% discount for spending more than $100.00 is scheduled to begin on January 1st and end on June 30th. The second rule wherein the customer is offered a discount of 10% for purchasing at least 10 items is scheduled to begin on July 1st and end on December 31st. The third rule wherein the customer is offered a discount of 25% for purchasing at least 10 items in the month of December is scheduled to begin on November 15th and to end on December 26th. Each of these three rules will only be executed on dates occurring within the prescribed time periods.
In addition to specifying time periods during which a given rule is either applied or not applied, it is often desired to vary the priority of a given rule relative to the other rules. For example, the third rule is given priority over the second rule during the holiday season, and, conversely, the second rule is given priority over the third rule at all other times of the year. Variable priority is achieved in the rule set of the proceeding paragraph, for example, by assigning a priority value of 2 to the first and second rules and a priority value of 1 to the third rule. However, the priority values assigned to the rules themselves are fixed, and do not vary over time.
Conventional rule ordering and priority systems express simple interrelationships among the rules in the rule set and fail to address the need to specify the varying of the priority value assigned to a rule using more complex functions. In particular, current rule authoring systems do not enable the application of time dependent priorities. As was illustrated in the proceeding paragraph, current rule authoring systems require a new or separate version of the rule for each time period and for each priority.
In addition to creating and expressing priorities among the plurality of rules in a given rule set, authoring systems attempt to provide for the manipulation of data. Data manipulation is used to model real-world or actual situations and variables that business users encounter. Traditionally, authoring and data manipulation systems were created by programmers for use by other programmers. Therefore, the interfaces are not business-user friendly, providing a format that is not natural, intuitive or easily understandable to a typical business user.
The intended progression of business rules expressed in more natural, non-formal language can be ambiguous or open to more than one interpretation. For example, the instruction to please hand someone the bat and the ball or the glove can be interpreted in at least two ways. This instruction can be interpreted to state that the person is to be handed the bat and ball or the bat and glove. Alternatively, the instruction can be interpreted to state that the person is to be handed the bat and the ball or just the glove. Additional information is needed to clarify how this instruction is to be interpreted.
Additional conjunctions, for example the conjunctions either or both, can be used to provide this additional information and to eliminate any ambiguity in the instruction. For example, the instruction can be reworded as the instruction to give someone the bat and either the ball or the glove. Alternatively, the instruction can be written as please give someone both the bat and the ball or the glove. However, even though the word both is utilized in the instruction, the instruction is still susceptible to two different interpretations.
Ambiguities can also be resolved through the use of generally accepted and widely applied precedence rules that convey the intended meaning unambiguously. An example of such precedence rules is found in the construction of algebraic expressions that use operator precedence to assign unambiguous meaning to a given expression. As long as the author and the reader are familiar with the established precedence, the meaning of a given algebraic expression is clearly conveyed. For example, the expression x=3+4×5 is understood to imply that 4 is multiplied by 5 followed by the addition of 3 since multiplication and division are performed first followed by addition and subtraction. Parentheses, however, are used to override the priority of multiplication and division. Thus, x=(3+2)×5 is interpreted to state that 3 and 2 are added together first and the resultant sum is multiplied by 5. Although universally accepted precedence is available when constructing algebraic expressions, similar precedence is not available when providing written directions or instructions as, for example, when constructing business rules.
Therefore, a need exists for a rule authoring system that provides for authoring of variable priorities for business rules and for the active and direct modification of the priorities by the author. Systems and structures are needed to communicate a desired hierarchy for written instructions or logical rules. Author interfaces are needed that are clear, concise and as consistent as possible with the thought processes of the business user. In addition, the tools that the business users are provided to interact with and manipulate the data are intuitive and understandable by the business user.

Method and apparatus for displaying and interacting with hierarchical information and time varying rule priority

International Business Machines Corporation


A bi-directional data pipeline for interfacing a memory with a communications port includes a series of four pipeline elements comprising two DMA buffers and first and second holding registers. A data word is transferred from memory to the DMA buffers, each holding one data byte of the data word. With each clock cycle, the data bytes are successively transferred through the two holding registers. Two comparators are used to determine if three successive identical data bytes are present in the pipeline. If three identical bytes are detected, run length encoding is enabled, and a run length count register is incremented for each successive identical byte received through the pipeline. The run length count and associated data byte are transferred to a FIFO for transmission over the data path. A tag associated with the run length count distinguishes the run length count from data bytes in the FIFO. Data received through the FIFO is decompressed by detecting the run length count tag and loading the run length count into the run length count register. The associated data byte is loaded into one of the holding registers and copied with each successive clock cycle, decrementing the run length count register. System development tools are provided with the pipeline for debugging purposes.

Data transmission rates necessary for modern, high performance computer printers and peripherals are much higher than early model printers. For example, early computer printers using daisy wheel or dot matrix impact printing technologies relied upon a limited number (e.g., 128) of character codes (typically ASCII) transmitted by a host computer to generate and print characters. Further, the printing rate of such early impact printers (on the order of several characters per second) did not require a high data transmission rate.
More advanced dot matrix printers having limited graphics functions typically did not require great data bandwidth, as resolution (dots per inch) was limited. Simple serial (e.g., RS-232) or parallel interfaces (e.g., Centronics.TM. or the like) were more than suitable for these early printing devices.
However, newer printers, (e.g., laser printers or the like) are capable of more complex graphics functions, greater print speeds, and two-way communication between the device and a host computer (e.g., network applications or the like). In addition, new peripherals have been developed for graphics use (e.g., scanner or the like) which require transmitting large amounts of data to a host computer. Thus, typical prior art parallel port interfaces (e.g., Centronics.TM. or so-called LPT ports or the like) have proved to be a bottleneck in data transmission from a host computer to a high performance printer, or from a scanner to a host computer.
In addition, newer, more sophisticated peripheral devices such as laser printers, have increased needs for two-way communication between a host computer and the peripheral, such as in network printer applications. Prior art parallel port interfaces were not suitably adapted to readily provide such two-way communication.
New parallel interface standards have been adapted to improve over the prior art Centronics.TM. ports. One example of such a standard is the IEEE P1284 specification or the Industry Standards Associate (ISA) Extended Capabilities Port (ECP) protocol both of which are incorporated herein by reference. These new protocols may be provided in a communications port which is backwardly compatible with earlier communications standards (e.g., Centronics.TM. or the like). The ECP protocol allows for Direct Memory Access (DMA) to improve data transmission rates. In addition, the ECP protocol may be provided with Run Length Encoding (RLE) to compress data and further increase data transmission rates.
RLE can compress up to 128 bytes of identical data into two bytes of information, thus providing up to a 64:1 compression ratio. In printing and scanning applications, repetitive data bytes are common. For example, in alphanumeric printing applications, a repeated number of ASCII characters may be transmitted representing blank spaces (i.e., ASCII 32, or 0010000). In graphics applications, where raster scanning techniques may be used to represent individual pixels or dots of information, large amounts of repetitive pixels may be transmitted to draw, for example, a straight line, or represent a large blank area. RLE compresses the data into a command byte representing the number of times the byte is repeated, and a data byte, which represents the byte to be repeated.
To decompress the data, the process is reversed. The command byte is received, and the peripheral device (or computer host, depending on direction of data transmission) repeats the following byte the number of times indicated by the command byte. In the ECP protocol, the computer host or peripheral distinguishes from command and data bytes by monitoring the HostAck (nAutoFd) pin (pin number 14). When the HostAck pin is high, the information transmitted on pins 2 through 9 is a data byte. When the HostAck pin is low, the information transmitted on pins 2 through 9 is a command byte. If the most significant bit (MSB) of the command byte is low, the command is a run length count. Thus, only seven bits are available for a maximum run length count of 128.
Although the ECP protocol provides for the use of run length encoding, the protocol does not set forth an efficient and economical technique for performing run length encoding. An intuitive approach to performing such encoding might comprise storing data within a memory, and compressing the data into RLE format before transmission by performing encoding operations on the data in memory. However, such a technique is time consuming and may require additional hardware or operation steps.
Thus, it remains a requirement in the art to provide an economical and efficient technique for implementing run length encoding in the ECP protocol.

Tagged data compression for parallel port interface