The present disclosure is related to methods and systems for determining longitudinal position of an elongated web.
Fabrication of many articles, including flexible electronic or optical components, involves registration between layers of material deposited or formed on an elongated substrate or web. The formation of the material layers on the web may occur in a continuous process or a step and repeat process involving multiple steps. For example, patterns of material may be deposited in layers on an elongated web through multiple deposition steps to form layered electronic or optical devices. Other articles require precise registration of features that are applied on one or both sides of the web.
To achieve accurate registration between the layers, lateral crossweb positioning and longitudinal downweb positioning must be maintained as the web moves through multiple manufacturing steps. Maintaining registration between layers formed on the web becomes more complex when the web is flexible or stretchable. Fabrication of some articles involves multiple passes (or stages) that apply material or processes to the web and which require precise position registration between the process steps.
Embodiments of the present disclosure involve methods and systems for determining the longitudinal position of an elongated web. One embodiment involves a method of generating an error signal representing the error in an estimated error signal. Fiducials disposed along a longitudinal axis of a substrate are sensed and corresponding sensor signals are generated based on the sensed fiducials. One or more web movement signals are generated, such as by the encoder of a web transport pull roller. A phase difference between the sensor signals and the movement signals is determined. An error signal is generated based on the phase difference.
Another embodiment of the invention is directed to a web position system. A sensor module senses one or more fiducials disposed along a longitudinal axis of a substrate and generates one or more continuous, periodic sensor signals based on the fiducial marks. A signal generator generates one or more continuous, periodic signals based on movement of the substrate. A phase detector determines a phase difference between the sensor signals and the movement signals and generates an error signal based on the phase difference.
The above summary of the present disclosure is not intended to describe each embodiment or every implementation of the present disclosure. Advantages and attainments, together with a more complete understanding of the disclosure, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.
While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It is to be understood, however, that the intention is not to limit the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
In the following description of the illustrated embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration, various embodiments in which the disclosure may be practiced. It is to be understood that the embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.
Embodiments described in the present disclosure illustrate methods and systems for determining the longitudinal position of a web based on continuous fiducial markings disposed longitudinally on the web. Determination of the position of an elongated web allows alignment of the web during successive processing steps. For example, embodiments of the disclosure may be used to facilitate alignment between multiple layers of material deposited on a web during a roll to roll manufacturing process. The processes described herein are particularly useful for aligning the layers of multi-layer electronic devices formed on a web. Approaches using discrete fiducial marks disposed on the web to determine the longitudinal web position only provide periodic position detection and do not provide position information during intervals between the discrete marks. The fiducial marks illustrated by the various embodiments discussed herein may be used to provide continuous longitudinal position updates and more accurate web positioning.
The approaches of the present disclosure automatically compensate for changes in web strain that commonly occur in web processing applications. As web strain is increased (i.e. the web is stretched more) the longitudinal web fiducials are stretched along with corresponding elements or features formed on the web. This allows the web fiducials to be used to accurately track the position of elements deposited on the web. For example, the fiducials may be deposited on the web substantially simultaneously with a layer of web elements. As the fiducials and the web elements are deposited, the elements deposited on the web and the fiducials experience the same amount of web strain. The fiducials may be used to accurately track the position of the web elements, regardless of the amount of web strain in subsequent processes. Using the approaches described herein, accurate registration to web elements can be achieved even when the web is stretched.
The fiducial marks may be non-periodic or periodic functions with respect to the web longitudinal axis, for example. As described in more detail below, periodic fiducial marks may be used to determine both coarse and fine position of the web. The combination of coarse and fine position information provides high resolution position measurement over a large distance.
In some embodiments, a single substantially continuous fiducial mark may be used to determine longitudinal position. A single substantially continuous fiducial mark is illustrated as a sinusoidal mark 101 disposed along the longitudinal axis 102 of the web 100 in
In some embodiments, the fiducial marks may comprise piecewise continuous marks as illustrated in
Substantially continuous fiducial marks such as those illustrated in
In some implementations, lateral web motion is determined using the web edge or fiducial marks disposed on the web. For example, a web edge or horizontal line disposed on the web may provide lateral position information. The lateral position reference may be used in addition to the one or more continuous fiducial marks that provide longitudinal position information.
The fiducial marks comprise patterns made on the web or applied to the web. In optical configurations, the fiducial marks modulate either transmitted or reflected light. The marks may be made or applied to the web by contact direct printing, ink jet printing, laser printing, laser marking, ablation, microreplication, scribing, embossing, casting, coating and/or other methods.
As illustrated in
The output of the camera 212 is directed to image data acquisition circuitry 214 that acquires and digitizes the image of the fiducial marks 204-206 from the camera 212. The digital image of the fiducial marks from the image data acquisition circuitry 214 is directed to a digital image processing system 216. The digital image processing system 216 analyzes the image to generate signals corresponding to the sensed fiducial marks. The signals generated by the digital image processing system 216 may be output to a longitudinal position detector 218 and optionally to a lateral position detector 220. Information from the lateral web position detector 220 may be used by the longitudinal web position detector 218 to enhance interpolation of the longitudinal web position. The longitudinal and lateral position determined by the longitudinal web position detector 218 and the lateral web position detector 220, respectively, may be output to a movement control system configured to control the longitudinal and lateral position of the web. Using substantially continuous fiducial marks for longitudinal web positioning, the position of the web may be determined to an accuracy of better than 1 micron. The accuracy and resolution are determined by several factors. One factor is the level of contrast in the fiducial marks produced by the marking process and available to the sensor. The higher the contrast, the greater resolution that will be possible. Another factor affecting accuracy and resolution is how small the repetitive cycle (period) can be made. Yet another factor affecting accuracy and resolution is the resolution of the sensor. For example, with a sinusoid fiducial having a 1 mm period and 12 bit sensor resolution, a resolution of about 0.25 microns or even about 0.1 micron is attainable.
The substantially horizontal fiducial mark 206 may be used for lateral position sensing. Additionally or alternatively, the horizontal fiducial mark 206 may be used as a reference fiducial to determine the amplitudes of the fiducial marks 204, 205.
In
The sine and cosine marks 204, 205 may be scaled to achieve maximum resolution. For example, the amplitudes of the marks may be made as large as possible to maximize the marks 204, 205 within the image view 270, 280, 290 of the sensor, with some margin to allow for lateral position errors. The longitudinal scaling may be selected based on expected speed of operation. Using a sharper pitch of the sine and cosine marks 204, 205 (higher frequency and smaller peak to peak distance) provides steeper slopes, and more resolution in the longitudinal direction. An excessively high pitch can reduce signal to noise ratio and also increases the required sampling rate. The minimum sampling rate requires that no more than ½ cycle passes between samples. However, operation is enhanced when a sampling rate at least 3 to 4 times the minimum sampling rate is used. The achievable sampling rate varies with the type of sensor used, but rates in excess of 1 kHz are possible with camera sensors.
The diagram of
Periodic fiducial marks, such as sine and/or cosine marks contain information that may be used to determine coarse and fine position of the web. The coarse position may be determined from periodically recurring features of the periodic fiducial marks. In the case of sine or cosine fiducial marks, the periodically recurring features used to determine coarse longitudinal position of the web may include peaks or zero crossings, for example.
In one embodiment using sine and cosine fiducial marks, zero crossings of each cycle are counted to determine coarse position. By taking the arctan2 function, with proper sign handling of the sine and cosine signals, the fine position within any cycle may be determined. The diagram of
The sine and cosine signals are digitized and may be filtered or otherwise processed. The system searches 440 for a zero crossing of the sine mark. When the zero crossing is located, the zero crossing is counted and the coarse web position is determined 450. The arctan-2 function of the sine and cosine signal values is calculated 460. The angle and quadrant determined from the arctan2 calculation provides 460 the fine position of the web referenced from the closest zero crossing.
The photograph of
In some embodiments, improvements in the sensor signals may be achieved by linear or non-linear filtering. For example, if a current web speed is known or estimated, bounds can be placed on the next estimated position update. Any value outside these bounds may be assumed to be noise. In particular, recursive filtering, such as through the use of a Kalman filter, may be used to improve the estimated web position. A Kalman filter uses two or more sources of information and combines them to form the best estimated value based on knowledge of the signals' statistics. The statistics may be generated in real time, or for stationary processes may be generated offline to reduce the computational burden.
Some embodiments of the invention involve calculating web position error which may be used in a feedback loop to improve the accuracy of the web position determination. The web position error may be determined by comparing the phase of one or more web movement signals generated by an encoder on a web transport roller, for example, with the phase of one or more signals generated by sensing the fiducials on the web. The web movement signal, e.g., the encoder signal, provides an estimated web position. The phase difference between the web movement signal and the fiducial sensor signal represents the web position error. In some implementations, the web position error signal is used to adjust the web movement signal so that the web movement signal is phase-locked to the fiducial sensor signal. As described in more detail below, phase locking the web movement signal with the fiducial sensor signal increases the accuracy of the web position determination.
The error detection system of
The error signal 850 can be used to improve the accuracy of the encoder signals 821.
The adjusted web position signal 825 provides enhanced web position determination at least in part because the adjusted web position signal 825 is “cleaner” (less noisy) than the sensed fiducial signals 811. The feedback approach described in
The multiplication circuitry 940, 942 calculates the product of the sine sensor signal and the cosine encoder signal and the product of the cosine sensor signal and the sine encoder signal. Based on the trigonometric identity, the sine of the phase difference sin(u±v) is calculated as follows:
sin(u±v)=sin(u)cos(v)∓cos(u)sin(v) Equation 1
where sin(u) is the sine sensor signal; cos(v) is the cosine movement signal; cos(u) is the cosine fiducial signal; and sin(v) is the sine movement signal. The products sin(u) cos(v) and cos(u) sin(v) are input to the summation block 960. The output 961 of the summation block 960 is the sine of the phase error between the fiducial sensor signals and the encoder signals. As illustrated in
Circuitry 962 takes the arcsin of the phase error signal 961, generating the web position error in radians. The error signal is applied to control circuitry 970, such as a proportional-integral-derivative (PID) controller, or other type of controller. The output of the controller 970 can be used to adjust the encoder signals as discussed in connection with
Web movement signals are generated 1020 based on web movement. As previously discussed, an encoder used to track web movement can provide the web movement signals. The phase difference between the fiducial sensor signals and the web movement signals is calculated 1025. An error signal is generated 1030 based on the phase difference. In one optional process, the error signal may be used to adjust 1035 the encoder signals. The web position can be determined 1040 based on the adjusted encoder signals. As another optional process, the error signal may be used 1050 to control other aspects of a fabrication process, such as web speed. In some applications, both optional processes illustrated in
Phase locking to determine an adjusted web position as described in connection with
The readjustment of the web pattern can be accomplished based on discrete fiducial marks (zero marks) disposed on the web which are used in conjunction with the continuous fiducial marks. The discrete marks are used by substrate position circuitry to determine an absolute web position corresponding to the start of a pattern and the continuous fiducials are used to determine web position within the pattern area.
As the web position is being tracked by the substrate position circuitry, a secondary sensor identifies the passing of a zero mark 1112, 1113. The output 1150 of the secondary sensor is illustrated in
The embodiments described herein involving continuous fiducial marks provide for continuous tracking of the longitudinal position of a moving web. Simple approaches may be used to apply the web fiducials to general purpose webs such as webs made of paper, fiber, woven or nonwoven material. The webs may comprise polyester, polycarbonate, PET, or other polymeric webs. The redundancy available through the use of sine and cosine marks provides high noise immunity and allows accurate web positioning. The approaches are particularly useful when used in conjunction with flexible webs.
The foregoing description of the various embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.
This application is a divisional filing of U.S. application Ser. No. 13/130,592, filed May 23, 2011, which is a national stage filing under 35 U.S.C. 371 of PCT/US2009/066945, filed Dec. 7, 2009, which claims priority to Provisional Application No. 61/141,128, filed Dec. 29, 2008, the disclosure of which is incorporated by reference in its/their entirety herein.
Number | Name | Date | Kind |
---|---|---|---|
1898723 | Fuller | Feb 1933 | A |
3570735 | Kurz | Mar 1971 | A |
3615048 | Martin | Oct 1971 | A |
3667031 | Cox, Jr. | May 1972 | A |
4010463 | Kay | Mar 1977 | A |
4021031 | Meihofer | May 1977 | A |
4049213 | Hank | Sep 1977 | A |
4284221 | Nagel | Aug 1981 | A |
4363271 | Horst | Dec 1982 | A |
4401893 | Dehuysser | Aug 1983 | A |
4485982 | St. John | Dec 1984 | A |
4529922 | Ono | Jul 1985 | A |
4532430 | Ross | Jul 1985 | A |
4569584 | St. John | Feb 1986 | A |
4610739 | Jensen | Sep 1986 | A |
4697485 | Raney | Oct 1987 | A |
4731542 | Doggett | Mar 1988 | A |
4734868 | DeLacy | Mar 1988 | A |
4808832 | Doggett | Feb 1989 | A |
4893135 | Jamzadeh | Jan 1990 | A |
4924266 | Negoro | May 1990 | A |
4945252 | Lerner | Jul 1990 | A |
5300961 | Corona | Apr 1994 | A |
5355154 | Guerin | Oct 1994 | A |
5384592 | Wong | Jan 1995 | A |
5450116 | Weiselfish | Sep 1995 | A |
5579092 | Isobe | Nov 1996 | A |
5667123 | Fukuda | Sep 1997 | A |
5768776 | Pendse | Jun 1998 | A |
5778724 | Clapp | Jul 1998 | A |
5859707 | Nakagawa | Jan 1999 | A |
5870204 | Chiu | Feb 1999 | A |
5875023 | Burke | Feb 1999 | A |
5931097 | Neifert | Aug 1999 | A |
6053107 | Hertel | Apr 2000 | A |
6056180 | Crowley | May 2000 | A |
6087655 | Kobrin | Jul 2000 | A |
6164201 | Burke | Dec 2000 | A |
6199480 | Leonhardt | Mar 2001 | B1 |
6206263 | Rich | Mar 2001 | B1 |
6273313 | Noll | Aug 2001 | B1 |
6322236 | Campbell | Nov 2001 | B1 |
6336019 | Castelli | Jan 2002 | B2 |
6375870 | Visovsky | Apr 2002 | B1 |
6396073 | Taylor | May 2002 | B1 |
6495214 | Nentwich | Dec 2002 | B1 |
6505906 | Bland | Jan 2003 | B1 |
6521905 | Luxem | Feb 2003 | B1 |
6647128 | Rhoads | Nov 2003 | B1 |
7121496 | Jackson | Oct 2006 | B2 |
7133630 | Sakai | Nov 2006 | B2 |
7296717 | Swanson | Nov 2007 | B2 |
7526230 | Kudo | Apr 2009 | B2 |
7560718 | Wittmann | Jul 2009 | B2 |
7573580 | Swindal | Aug 2009 | B2 |
7826041 | Takeda | Nov 2010 | B2 |
8405831 | Carlson | Mar 2013 | B2 |
20020018220 | Aoki | Feb 2002 | A1 |
20020121131 | Mancevski | Sep 2002 | A1 |
20020122186 | Igaki | Sep 2002 | A1 |
20030218125 | Igaki | Nov 2003 | A1 |
20040022557 | Kudo | Feb 2004 | A1 |
20040197443 | Scarabelli | Oct 2004 | A1 |
20040227644 | Lin | Nov 2004 | A1 |
20040240513 | Del Puerto | Dec 2004 | A1 |
20040262505 | Atsuta | Dec 2004 | A1 |
20050218237 | Lapstun | Oct 2005 | A1 |
20050232475 | Floeder | Oct 2005 | A1 |
20050263689 | Atsuta | Dec 2005 | A1 |
20050274880 | Atsuta | Dec 2005 | A1 |
20060174992 | Brost | Aug 2006 | A1 |
20060210714 | Huizinga | Sep 2006 | A1 |
20070099396 | Hirai | May 2007 | A1 |
20070138153 | Redman | Jun 2007 | A1 |
20080039718 | Drinan | Feb 2008 | A1 |
20080073493 | Atsuta | Mar 2008 | A1 |
20080219741 | McNestry | Sep 2008 | A1 |
20100097462 | Carlson | Apr 2010 | A1 |
20100187277 | Carlson | Jul 2010 | A1 |
20100188668 | Carlson | Jul 2010 | A1 |
20100196607 | Carlson | Aug 2010 | A1 |
Number | Date | Country |
---|---|---|
2447719 | Sep 2001 | CN |
101191784 | Jun 2008 | CN |
197 54 776 | Jun 1999 | DE |
0680829 | Nov 1995 | EP |
0 838 665 | Apr 1998 | EP |
1 235 054 | Aug 2002 | EP |
1 722 021 | Nov 2006 | EP |
2 065 871 | Jul 1981 | GB |
2 195 179 | Mar 1988 | GB |
62-111860 | May 1987 | JP |
02-037963 | Aug 1990 | JP |
05-010725 | Jan 1993 | JP |
07-181032 | Jul 1995 | JP |
11-167165 | Jun 1999 | JP |
2005-049237 | Feb 2005 | JP |
2005-178962 | Jul 2005 | JP |
WO 2005106104 | Nov 2005 | WO |
WO 2006107057 | Oct 2006 | WO |
WO 2007027757 | Mar 2007 | WO |
WO 2008088650 | Jul 2008 | WO |
WO 2010077719 | Jul 2010 | WO |
Number | Date | Country | |
---|---|---|---|
20140368185 A1 | Dec 2014 | US |
Number | Date | Country | |
---|---|---|---|
61141128 | Dec 2008 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 13130592 | US | |
Child | 14469662 | US |