Cross-Reference to Related Applications

[0001] This application claims priority from US application No. 62/322874 filed

15 April 2016. For purposes of the United States, this application claims the benefit under 35 U.S.C. §119 of US application No. 62/322874 filed 15 April 2016 and entitled

MAINTAINING ALIGNMENT WHILE TURNING OVER A PANEL which is hereby incorporated herein by reference for all purposes.

Field

[0002] This invention relates to apparatus and methods for performing operations in register on opposing sides of a panel. The invention has example application to making two-sided and multi-layer circuit boards.

Background

[0003] There are various applications in which it is desirable to form aligned patterns on opposing faces of a panel. An example of such an application is forming conductive patterns on opposing sides of a panel of a circuit board.

[0004] Electronic devices often include electrical circuits made up of circuit boards populated with electronic components. A typical circuit board comprises an electrically- insulating substrate, such as fiberglass, having a pattern of electrical conductors on one or both faces. Some circuit boards are made by bonding together two or more panels which each comprise a substrate having electrical conductors patterned on one or both faces of the panel. It is often useful to make circuit boards in which one or more substrates has patterned electrical conductors on both of its faces. For example, some circuit boards are made by laminating together several two-sided panels with electrically-insulating layers of adhesive (e.g. a suitable fiber-reinforced epoxy) separating adjacent panels. [0005] Patterned layers of electrical conductors may be formed in various ways. One approach is to use an etching process. For example, a copper clad double-sided panel may be coated with a resist material that changes properties when exposed. Exposure may, for example involve exposure to light, heat, an electron beam or the like. Some parts of the resist material are exposed and other parts are left unexposed, a process sometimes called 'imaging'. After imaging either the exposed portions of the resist material or the unexposed portions of the resist material are removed (depending on the type of resist). [0006] In an example case, exposure to light hardens exposed portions of the resist and unexposed portions of the resist are subsequently washed off to leave the underlying copper bare. A chemical or physical etching process can then be used to remove the copper from the areas in which the resist has been removed, to leave a desired pattern. The light-hardened resist material prevents the copper from being etched away in the exposed areas.

[0007] Exposing the resist material for imaging may be achieved, for example, by using a film to mask the areas where the copper must be removed or by using a digital imaging machine in which a computer directs one or more beams of light to image the resist.

[0008] Regardless of the precise process used to pattern opposing sides of a panel, it is necessary that the patterns formed on each side of the panel are accurately aligned to each other. One way to achieve such alignment is to make marks at known locations on opposing faces of the panel and to align the image made on each face of the panel to the marks. Such marks may be created, for example, by making two or more registration holes in the panel. A first side of the panel may be imaged then the panel may be removed from the imaging device, flipped over, and then replaced on the imaging device to image the second side of the panel. The registration holes or marks are used to align the second image to the first image.

[0009] Removal and flipping of the panel may be manual or automatic. With current technology, if a panel is to be flipped automatically it typically is taken from the imaging table using a vacuum pickup, transferred to a second vacuum pickup and then placed back on the original or another imaging table. This requires three transfers.

[0010] Imaging a panel often involves holding the panel flat during imaging. Typically, this is achieved by placing the panel on a flat surface called an imaging table that is typically, but not necessarily, a vacuum table. With the panel held on the imaging table the first side is imaged by exposing it to radiation (such as visible or nonvisible light).

Clamping is sometimes required for thick (assembled) panels because such panels may be warped, and a vacuum may be insufficient to hold or flatten the panel.

[0011] There is a need for alternative methods for imaging panels, such as panels for circuit boards. There is a particular need for methods and apparatus that are cost effective in comparison to the current state of the art.

Summary

[0012] This invention has a number of aspects. These include without limitation:

• Apparatus useful for imaging opposing faces of panels such as, for example, circuit boards or layers for circuit boards; and

• Methods for imaging opposing faces of panels such as circuit boards or layers for circuit boards.

[0013] In a non-limiting example aspect, an apparatus for imaging panels includes an imaging device and first and second tables each capable of holding a panel. Actuator mechanisms are provided to move each table among a panel pickup position, an imaging position and a transfer position. The actuator mechanisms are not required to position the tables to a high degree of accuracy. The apparatus includes registration features associated with each of the tables and the imaging device. The registration features are operable to repeatably guide either one of the tables into a corresponding predetermined imaging position relative to the imaging device in which the imaging device is operable to image one face of a panel supported on the table and to repeatably guide the tables into a predetermined face-to-face transfer position relative to one another. The tables may comprise vacuum tables.

[0014] In operation, a panel may be imaged on both sides (faces) such that a first side image and a second side image are accurately registered relative to one another. A panel is placed on the first table which is moved to the imaging position and a first image is imaged on a first face of the panel by the imaging device. The first and second tables are moved to the transfer position and the panel is transferred from the first table to the second table. The first image is now at a known position relative to the second table. The second table is then moved to its imaging position and a second image is imaged onto a second face of the panel by the imaging device. The second image may be accurately registered to the first image even if the panel is not positioned particularly accurately onto the first table and even if the mechanisms that move the tables among the different positions are not capable of controlling positions of the tables to high accuracy.

[0015] In some embodiments panels are marked, perforated, punched, drilled, shaped or the like with indicia, apertures, holes, patterns or the like that are registered to the first and second images. This may be done, for example, by providing a device operable to form such indicia, apertures or the like and using the registration features to align a table carrying the panel with the device before operating the device to form the indicia, aperture etc.

[0016] Further aspects and example embodiments are illustrated in the accompanying drawings and/or described in the following description.

Brief Description of the Drawings [0017] The accompanying drawings illustrate non-limiting example embodiments of the invention.

[0018] Figure 1 shows a panel perforated by holes.

[0019] Figure 1A shows a circuit board having patterns of conductive traces on first and second opposing faces of the circuit board. [0020] Figure 2 shows panel imaging apparatus according to an example embodiment with two imaging tables in a transfer configuration.

[0021] Figure 3 is an isometric drawing of apparatus like that of Figure 2 with the two imaging tables in a transfer configuration.

[0022] Figure 4 shows apparatus like that of Figure 2 with one imaging table in a load configuration and a second imaging table in an imaging configuration.

[0023] Figure 5 is a schematic diagram showing apparatus according to an example embodiment and illustrating possible positions for two imaging tables.

[0024] Figure 6A shows an example alignment mechanism operable to align two imaging tables.

[0025] Figure 6B shows an example alignment mechanism operable to align an imaging table and an imaging device.

[0026] Figures 7A through 7C are partially schematic perspective views of a panel imaging machine according to another example embodiment of the invention in different stages of imaging a panel.

[0027] Figure 7D is a partially schematic illustration of an example drive system for a carriage in an imaging machine

[0028] Figure 7E is a schematic side view showing positions for a panel support in different phases of an imaging operation.

[0029] Figure 7F is a block diagram of an example control system.

[0030] Figure 8 is a flow chart illustrating an example method for two-sided imaging of a panel.

Detailed Description

[0031] Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive sense.

[0032] One aspect of this invention provides apparatus and methods for patterning opposed faces of a panel in aligned relationship. This may be done using an apparatus which provides first and second holding tables (e.g. vacuum tables) each capable of holding the panel. A holding table is an example of a panel support. [0033] An example method applies patterning (imaging) to a first face of the panel while the panel is held to the first holding table; bringing the first holding table face-to-face with the second holding table, such that the first and second holding tables are in a known relative alignment; transferring the panel to the second holding table by holding the panel to the second holding table and releasing the panel from the first holding table; and imaging a second face of the panel while the panel is held to the second holding table. In some embodiments, the same imaging apparatus is used to image both faces of the panel and the first and second tables each has a repeatable imaging position relative to the imaging apparatus. Figure 1 A shows an example of a panel P having first patterning 5 A on one face 6A and second patterning 5B on a second face 6B.

[0034] Figure 2 shows apparatus 10 according to an example embodiment. Apparatus 10 includes first and second imaging tables 12A and 12B (collectively or generally imaging tables 12). Imaging tables 12 may, for example, comprise vacuum tables. Imaging tables 12A and 12B are respectively movably supported by actuation mechanisms 14A and 14B (collectively or generally actuation mechanisms 14).

[0035] An imaging apparatus 16 is provided to image panels P. Imaging apparatus 16 may have any suitable mode of operation. Suitable imaging apparatuses are commercially available. Imaging apparatus 16 may for example, expose a face of a panel P by scanning one or more beams of light (visible or invisible) or a particle beam (e.g. an electron beam) across the face of the panel P or exposing the face of the panel P to light (visible or invisible) that has passed through a mask. Non-limiting examples of light that may be used to expose a resist on a panel include ultraviolet (UV) light and infrared light. Imaging apparatus 16 may, for example comprise a system of a type commonly described as digital imaging or maskless lithography or laser direct imaging. In another example, imaging apparatus 16 may comprise an imaging machine of the type that directly deposits a mask material such as an inkjet type imaging machine. Imaging apparatus 16 may also comprise an imaging machine of the type that deposits a conductor or a material that is convertible to a conductor (e.g. via heat or chemical conversion). For example, an inkjet imaging machine may print a partem in ink that is conductive or can be converted to be conductive in a subsequent processing step. [0036] In some embodiments, an imaging machine 16 has one or more imaging heads that are scanned relative to a panel. For example, imaging may involve scanning an imaging head in a raster pattern to image the entire panel or moving the imaging head to sequentially image distinct blocks of the panel etc. There are a wide range of possible configurations for imaging machine 16. In embodiments where imaging involves moving an imaging head relative to a panel P, either or both of the panel P and the imaging head may be moved to attain the desired relative motion. For example, an imaging head may be moved in one dimension (e.g. width-wise) and the panel may be moved in another direction (e.g. lengthwise). [0037] Figure 5 shows possible configurations for actuation mechanisms 14 and tables 12. Actuation mechanism 14A is operative to move imaging table 12A between a loading position 18-1 where a panel may be received onto table 12A, an imaging position 18-2 where table 12A holds a panel P in a position where a first face P-l of the panel P can be imaged by imaging device 16 and a transfer position 18-3 where the panel P can be transferred to second table 12B. Actuation mechanism 14B is operative to move imaging table 12B between a transfer position 19-1 at which a panel P can be received from first table 12A, an imaging position 19-2 where the second face P-2 of the panel P can be imaged by imaging device 16 and a discharge position 19-3 from which the panel P can be removed for further processing. [0038] When table 12A is in its transfer position 18-3 and table 12B is in its transfer position 19-1 tables 12A and 12B are face-to-face and a panel P is sandwiched between the faces of imaging tables 12A and 12B. Front faces of imaging tables 12 may be resiliently mounted (e.g. spring loaded) to accommodate panels P of different thicknesses.

[0039] When tables 12A and 12B are in this transfer configuration, an alignment mechanism 20 holds table 12B in a position relative to table 12A that is precisely repeatable. In preferred embodiments alignment mechanism 20 consistently fixes the relative positions of imaging tables 12A and 12B to within ± 25 μιτι in both of two perpendicular directions in the plane of imaging tables 12 (e.g. X and Y directions).

[0040] Alignment mechanism 20 may take any of a wide variety of forms. For example, alignment mechanism 20 may comprise: • One or more pins or other projections that engages in a corresponding aperture when imaging tables 12A and 12B are brought together into their transfer configuration (in some embodiments the projections comprise tapered registration pins);

· One or more steps, faces or other abutment surfaces that engages a corresponding step, face, edge or other abutment surface when imaging tables 12A and 12B are brought together into their transfer configuration;

• One or more sensors mounted to one of imaging tables 12A and 12B that detects one or more targets on the other one of imaging tables 12A and 12B and an actuation system that automatically moves tables 12A and 12B relative to one another to achieve alignment of each sensor with the corresponding target (targets may, for example comprise optically-detected surfaces, optical elements or markings or magnets or surfaces detected by a displacement probe etc.); and/or

• Any combinations of the above. [0041] Elements of alignment mechanism 20 (or another alignment mechanism) are also operable to repeatably align first imaging table 12A to imaging device 16 when first imaging table 12A is in its imaging position 18-2.

[0042] Elements of alignment mechanism 20 (or another alignment mechanism) are also operable to repeatably align second imaging table 12B to imaging device 16 when second imaging table 12B is in its imaging position 19-2.

[0043] As shown in Figure 6A, alignment mechanism 20 may include tapered pins 20A which project from first imaging table 12A and tapered pins 20B which project from second imaging table 12B. When imaging tables 12A and 12B are in the transfer configuration described above, tapered pins 20A may be received in corresponding mating recesses 21B in second imaging table 12B and tapered pins 20B are received in corresponding mating recesses 21A in first imaging table 12A. In some embodiments some of recesses 21A or 21B are oversize for the corresponding pin to avoid binding as tables 12 are brought together into their transfer configuration.

[0044] Pins 20A may be operative to align first imaging table 12A in position 18-2 to imaging device 16 (e.g. by being received into corresponding mating recesses 21 C positioned on or in a fixed relationship to imaging device 16). Pins 20B may be operative to align second imaging table 12B in position 19-2 to imaging device 16 (e.g. by being received into corresponding mating recesses 21D positioned on or in a fixed relationship to imaging device 16). [0045] In other embodiments, tapered pins 20A and 20B may be equally spaced, and imaging device 16 may have one set of mating recesses for receiving both sets of pins 20.

[0046] In another example embodiment an alignment mechanism 20 includes elements projecting forwardly along one or more edges of one table (e.g. a border, flange, set of fingers, pins, and/or the like). These elements may engage an edge of another table or device such that the elements help to bring the one table into alignment with the other table or device.

[0047] In some embodiments one or more parts of an alignment mechanism fix alignment relative to one axis while allowing some motion relative to another axis. A set of two or more such alignment mechanisms may fix the relative locations of a table and another table or device while providing some accommodation for relative movements due to differential thermal expansion between two tables or between a table and apparatus such as imaging device 16 or an aperture forming apparatus. In some embodiments, alignment features comprise slots that receive mating projections. The projections (e.g. pins) may be free to slide longitudinally along the slots while engaged in the slots but may prevent relative motion in a direction perpendicular to the slots. Another example of an alignment feature that can accommodate relative motion along one axis while preventing motion in another direction is a step against which a second member can abut.

[0048] In an example embodiment one or more alignment mechanisms comprises a pin in the form of a spherical ball supported by a column smaller in diameter than the ball. Such a pin may engage in a corresponding hole or slot. The hole or slot may have a tapered entrance to receive the ball. This embodiment is advantageous in that the pin can enter the corresponding hole or slot even if the pin is somewhat angularly misaligned with the hole or slot. The hole or slot may be deep enough to allow the ball to position itself at depths that accommodate different thicknesses of panel P. [0049] For example, such a pin may be provided on one table 12 and a corresponding hole or slot may be provided on another table 12. Actuation mechanisms may bring the tables 12 together into their transfer configuration in such a way that surfaces of the tables 12 are not quite parallel when the ball engages the hole or slot. [0050] In a more specific embodiment the alignment mechanism comprises two pins, each comprising a ball supported by a column as described above. One of the pins engages a hole in the other table that is dimensioned to receive the ball with a fit tight enough to provide a desired accuracy of relative positioning. The other one of the pins may engage another hole or slot dimensioned to snugly receive the ball of the other pin. Both pins may be provided on one of the tables or one pin may be provided on each of the tables.

[0051] Some or all of the same features provided on tables 12 for the purpose of aligning tables 12 with one another in the transfer configuration may also be used to align tables 12 with imaging device 16 or another device. In the alternative, different features may be provided for aligning one or more of tables 12 with imaging device 16 or other devices. [0052] In some embodiments, imaging device 16 is configured with different patterns to be applied to different faces of a panel P and offsets which allow the placement of each partem to be fine-tuned.

[0053] In some embodiments, in addition to or as an alternative to an alignment mechanism as described above, apparatus as described herein includes a system for measuring any misalignment between two tables 12 and/or between a table 12 and c 16. The output of such a misalignment detection system may be used to control imaging machine 16 such that an image is applied at a desired location on a panel P. As an example of such a system, one or more sensors may be mounted to one of imaging tables 12A and 12B. Each sensor may detect the relative position of one or more targets on the other one of imaging tables 12A and 12B. An image position adjustment system may use the sensor output(s) to automatically adjust and or align the position of the second image to be recorded on a panel P to be in suitable alignment with the first image. An image position adjustment mechanism may take various forms such as physical position adjustment of an imaging head, physical position adjustment of the table relative to the imaging machine, physical position adjustment of optics (e.g. optics that adjustably aim or zoom), physical position adjustment of a mask and/or software adjustment or alignment of the image position. Such adjustment may include any or all of X or Y position, X or Y scaling or non-linear mapping.

[0054] Since one or more alignment mechanisms are provided which have the effect of repeatably and precisely guiding imaging tables 12A and 12B into alignment with imaging machine 16 in their respective imaging positions 18-2 and 19-2 and into alignment with one another in the transfer configuration (where first and second imaging tables 12A and 12B are respectively in positions 18-3 and 19-1) it is not necessary for actuation mechanisms 14A or 14B to be highly rigid or highly accurate. [0055] Actuation mechanisms 14A and 14B may take a wide variety of forms. The main requirements for actuation mechanism 14A are that actuation mechanism 14A is operable to position first imaging table 12A to any of positions 18-1, 18-2 and 18-3 and to carry imaging table 12A between those positions at a desired speed. The main requirements for actuation mechanism 14B are that actuation mechanism 14B is operable to position second imaging table 12B to any of positions 19-1, 19-2 and 19-3 and to carry imaging table 12B between those positions at a desired speed.

[0056] In the illustrated embodiment, actuation mechanism 14A is supported by a post 24A and comprises an arm 25 A. Arm 25A is pivotally mounted to post 24A and to first imaging table 12A. As a result, the configuration of actuation mechanism 14A is determined by angles of rotation of the two pivotal joints 27 A, and 28A. These angles of rotation may be controlled by a controller by way of suitable rotary and/or linear actuators (e.g. servo motors, stepper motors, hydraulic or pneumatic cylinders or motors, electrical actuators, etc.). In some embodiments actuation mechanisms 14 allow for a more than 360° rotation of arm 25A relative to post 24A, and/or of imaging table 12A relative to arm 25A through an angle of 360 degrees or more.

[0057] Second actuation mechanism 14B may be the same as or different from first actuation mechanism 14 A. In the illustrated embodiment, second actuation mechanism 14B is a mirror image of first actuation mechanism 14A and has post 24B and arm 25B connected to one another at rotary joint 27B, and second imaging table 12B connected to arm 25B at rotary joint 28B. This embodiment of second actuation mechanism 14B may operate in the general manner described above for first actuation mechanism 14A.

[0058] In an example embodiment:

• Arms 25 A and 25B can rotate 360° or more around corresponding pivot points 27 and 28

· Imaging tables 12A and 12B are connected to arms 25 A and 25B at pivot points

28A and 28B.

• Imaging tables 12A and 12B can rotate 360° or more around pivot points 28A and 28B.

• The rotation of the arms and imaging tables is independently controlled by motors (not shown in the diagram).

[0059] Panels P may be presented to the first imaging table 12A at its loading position 18- 1 in any of various ways. In the embodiment illustrated in Figure 2 panels P are presented in a horizontal orientation. In alternative embodiments panels P are presented in other orientations (e.g. panels P may be presented in a vertical orientation or at an angle that is neither horizontal nor vertical).

[0060] In the embodiment illustrated in Figure 2, panels P are presented in a stack and first imaging table 12A may be operated to pick panels P off of the stack one-by-one. In an alternative embodiment, panels P may be presented to first imaging table 12A at its loading position one-by-one. For example, panels P may be brought to the loading position by a suitable conveyor or robot (not shown).

[0061] Similarly, panels P may be received from second imaging table 12B at the discharge position 19-3 in any of various ways. For example, panels P may be placed or dropped onto a stack as shown in Figure 2, transferred to a conveyor system or robot (not shown) or the like. Second imaging table 12B may be horizontal or nearly horizontal at discharge position 19-3 as shown in Figure 5 or may have another suitable orientation. For example, at discharge position 19-3 second imaging table 12B may be vertical or nearly vertical or at some angle between horizontal and vertical.

[0062] Apparatus 10 may be operated by a suitable controller (e.g. a programmable controller such as a PLC or computer and/or a hardware controller suitably interfaced to control actuator mechanisms 12A and 12B and imaging device 16). The controller may coordinate the movements of tables 12 and the imaging of panels by imaging device 16.

[0063] Some embodiments may include an interface to imaging device 16. Imaging device 16 may be configured to select various imaging patterns to be used to image panels P in response to signals received by way of the interface. The interface may be manual or electronic. An electronic interface may allow for automated control of the imaging device. Automated control of the imaging device may be combined with automated control of the arms and tables to allow for a fully automated panel imaging system.

[0064] In operation, first imaging table 12A may be placed into its position 18-1 to receive a panel. In the illustrated embodiment, first imaging table 12A is placed face down on top of a stack of panels P. Then, first imaging table 12A is attached to the top panel P. This may involve, for example applying a vacuum at the surface of first imaging table 12A so that the panel P is held against first imaging table 12A by ambient atmospheric pressure.

[0065] First imaging table 12A may then be moved to its imaging position 18-2. As first imaging table 12A reaches imaging position 18-2 alignment mechanism 20 brings first imaging table 12A into alignment with imaging device 16. At this point imaging device 16 may image the proximate first face of the panel P to provide a desired first pattern.

[0066] In some embodiments, imaging imaging device 16 involves moving first imaging table 12A in coordination with the imaging operation. In such embodiments, part of alignment mechanism 20 may be moved together with first imaging table 12 A. For example, alignment features such as pins on table 12A may engage corresponding alignment features associated with imaging position 18-2. The corresponding alignment features may be carried on a translatable table which is controlled to provide the desired movement during imaging. [0067] First imaging table 12A and second imaging table 12B may then be moved to the transfer configuration described above. In the transfer configuration, holding of the panel P to the first imaging table 12A may be discontinued and holding of the panel P to the second imaging table 12B may be initiated. This may be done, for example, by applying a vacuum to the surface of second imaging table 12B and then discontinuing the vacuum at the surface of first imaging table 12 A. Panel P is now held to second imaging panel 12B with the already -imaged face of panel P against the surface of second imaging table 12B. Since alignment mechanism 20 holds first and second imaging tables 12A and 12B in a fixed relationship the patterning previously-applied to the first face of panel P has a known position relative to second imaging table 12B.

[0068] Second imaging table 12B can then be moved to its imaging position 19-2. As second imaging table 12B reaches imaging position 19-2 alignment mechanism 20 brings second imaging table 12B into alignment with imaging device 16. At this point imaging device 16 may image the proximate second face of the panel P to provide a desired second partem.

[0069] In some embodiments, imaging the second face of panel P involves moving second imaging table 12B in coordination with the imaging operation. This may be done in the same manner described above for first imaging table 12A.

[0070] The first and second patterns applied to either face of panel P are accurately registered to one another. While the second face of panel P is being imaged the first imaging table may be returning to pick up another panel P.

[0071] After the second face of panel P has been imaged, second imaging table may be moved to its discharge position 19-3 at which point the panel P may be released (e.g. by discontinuing vacuum at the surface of second imaging table 12B). Downstream processing (e.g. washing and etching etc.) may then be performed on the fully imaged panel P.

[0072] In an example embodiment, a normal operation cycle of the machine is as follows:

1. Imaging table 12A fetches a panel from the stack of panels for imaging.

2. Imaging table 12A moves the new panel to the imaging location using the

alignment mechanism.

3. The first side of the panel is imaged.

4. Imaging tables 12A and 12B move to the transfer position and are aligned using the alignment mechanism.

5. The panel is transferred from imaging table 12A to imaging table 12B. 6. Imaging table 12B moves to the imaging location.

7. The second side of the panel is imaged.

8. Imaging table 12A moves to pick up a new panel from the stack of panels for loading.

9. Following imaging of the second side of the panel, imaging table 12B moves to the offload stack to deposit the imaged panel.

10. Imaging table 12A moves a new panel to the image location.

Note: Many of the steps above can occur in parallel.

[0073] It is not mandatory that the panels are automatically loaded onto and off-loaded from imaging table 12A, 12B respectively. As one alternative, panels may be manually loaded onto imaging table 12A and/or manually offloaded from imaging table 12B.

[0074] In some cases it is desirable to form apertures in a panel P such that the apertures have a known relationship to the patterning on panel P. Such apertures may, for example, be used to position panel P for downstream operations such as installation of components or be used to align the multiple layers of panel P prior to laminating the assembled panels P together to form a multilayer board. Figure 1 shows an example panel P with a number of apertures formed in it. In some embodiments apparatus 10 includes a mechanism for forming apertures in panel P while the panel P is on the first or second imaging table 12 or on a separate aperture-making table. In either case alignment mechanism 20 or another alignment mechanism may be used to preserve a desired alignment of the apertures so- formed with the patterning on panel P. For example, apertures may be formed by one or more hole punches, drills, water jets, plasma cutters, chemical etching processes, solvent cutting, heat cutting , lasers or the like. Apertures may be made before imaging, after imaging or between imaging first and second faces of panel P. It is thought beneficial to perform imaging first and to form any apertures after imaging to avoid detritus from the aperture-making from fouling the imaging area.

[0075] In Figure 4, imaging table 12A is positioned to fetch a new panel from the stack of panels for loading while imaging table 12B is in the imaging location, positioned to image the second side of a panel. [0076] In some embodiments, the positions of imaging tables 12 and/or one or more components of actuation mechanisms 14 are monitored by one or more sensors. The sensors may be mounted, for example, on the tables, arms, pivot joints, and/or any other part of the apparatus. The sensors may measure rotation, distance, and/or acceleration. Output signals from the sensors may be provided to a controller configured to control the actuation mechanisms and to coordinate operation of the apparatus. For example, sensors such as micro switches, proximity switches, pressure sensors or the like may be mounted within mating recesses 21 to determine when alignment mechanisms 20 are properly engaged with the recesses, and the tables are properly aligned. Outputs from such sensors may be applied to trigger transferring a panel between tables. Similar measurements can be used to determine when table 12A is aligned to receive a panel from the loading stack, when table 12B is aligned to deposit a panel in the offloading stack, and/or when a panel is in position to be imaged.

[0077] Methods according to some non-limiting embodiments have one or more of the following characteristics:

• an imaging table moves to pick up a panel;

• an imaging table moves to offload a panel;.

• two imaging tables are used to turn over a panel to expose the second side, where the first imaging table transfers the panel to a second imaging table.

• misalignment between two tables is detected where a panel is being transferred between the tables and a degree of the misalignment is used to adjust the position of the image on the second side of a panel to align the first image to the second image.

• the imaging tables are aligned to each other and/or to the imaging location using physical, optical, magnetic, electrically conductive, inductive or capacitive features on the table.

• shaped surfaces engage to align imaging tables to each other to facilitate accurate transfer of a panel from one imaging table to another.

• shaped surfaces engage to align imaging tables to an imaging location to facilitate alignment for imaging.

• more than one imaging radiation or light source are used to image both sides in series while maintaining alignment between the sides.

• shaped surfaces engage to align imaging tables to a hole punch apparatus to

facilitate alignment of holes relative to the image on the panel.

[0078] Various embodiments of the illustrated actuation mechanism are possible. For example:

• In some embodiments, arms 25 are substantially the same length as each other, and substantially the same length as or longer than posts 24. This allows panels being carried by tables 12 to abut imaging device 16 when arms 25 are in position 18-2 or 19-2.

• In some embodiments, arms 25 have substantially equal lengths and shorter than posts 24. Additionally, arms 25 may be mounted on the interior of posts 24. This allows arms 25 full 360° movement around pivot points 27.

• In some embodiments, tables 12 have substantially equal lengths and are shorter than the combined length of arms 25 and posts 24. Additionally, tables 12 may be mounted on the interior of arms 25. This allows tables 12 full 360° movement around pivot points 28.

• In another embodiment, posts 24 are mounted a distance D from each other, where the length of arms 25 is greater than D/2. This allows tables 25 to abut one another when arms 25 are in positions 18-3 and 19-1.

• Apparatus according to some embodiments provides more than two tables. Each of the tables may be equipped with alignment feature(s) that facilitate repeatable alignment of the table with another one of the tables and with processing equipment (such as, for example, an imaging machine, aperture-making machine or the like). Any embodiment described herein may be modified to provide one or more additional table(s).

[0079] Figures 7A to 7D illustrate an imaging machine 70 according to another example embodiment. Machine 70 comprises first and second carriages 72A and 72B (collectively carriages 72) that are mounted to travel along a track 74. Track 74 constrains motion of carriages 72A and 72B to follow paths defined by track 74. Track 74 may, for example, be provided by one or more high-accuracy linear rail shafts or rail guideways. Carriages 72A and 72B may be coupled to such shafts or guideways with suitable linear bearings. [0080] As another example, carriages 72A and 72B may be supported on track 74 by air bearings. For example, track 74 may be provided by one or more dimensionally-stable precision rails (e.g. granite rails) that provide air-bearing surfaces for carriages 72A and 72B to ride on. Compressed air may be injected between air bearing surfaces on carriages 72A and 72B and such rails to allow carriages 72A and 72B to be moved along the rail or rails with very low friction along a path defined by the rails. Air bearings may be provided that constrain the carriage in all directions relative to the rail or rails. Advantageously such air bearings can constrain carriages 72A and 72B to repeatably follow the same path with very little deviation from the path in a transverse direction. [0081] The way in which carriages 72A and 72B are mounted for motion along respective paths may be varied. For example, separate tracks could be provided for carriages 72A and 72B.In Figures 7A to 7C track 74 comprises a pair of parallel linear members 74A and 74B that each comprise air-bearing surfaces. Each of carriages 72A and 72B is supported by air bearings on rails 74A and 74B. [0082] Carriages 72A and 72B respectively carry panel supports 76A and 76B

(collectively panel supports 76). Each panel support 76 is dimensioned to receive and support a panel to be imaged. Panel supports 76 are operative to hold a panel for imaging. For example, each of panel supports 76 may comprise a vacuum table. In a non-limiting example embodiment each of panel supports 76 comprises a vacuum table having a size sufficient to receive and support a panel having a size of about 24 inches by 32 inches (approximately 61 cm by 81 cm). The sizes of panel supports 76 may be selected to suit the sizes of panels to be imaged.

[0083] Panel supports 76 are each pivotally attached to the corresponding carriage 72 and are rotatable between an imaging position and a transfer position. In the illustrated embodiment, panel supports 76 comprise axles 77A supported in bearings 77B for rotation about an axis 77C that is transverse to (typically perpendicular to) track 74. Bearings 77B may be precision bearings which constrain panel support 76 to pivot about axis 77C. In Figure 7A, panel support 76A is in its imaging position and panel support 76B is in its transfer position. [0084] In the illustrated embodiment, pivot axis 77C crosses panel support 76 at or near the center of a panel support 76. This is advantageous for self-alignment of panel support s76 as discussed elsewhere herein and also for reducing the clearance to adjacent structures required to allow panel supports 76 to pivot. In some embodiments pivot axis 77C is located on a side of a panel being supported that is opposite to imaging machine 16. [0085] Actuators (not shown in Figures 7A to 7C) are provided to pivot panel supports 76 between their imaging and transfer positions and to move carriages 72A and 72B to desired positions along track 74.

[0086] When panel supports 76 are both in their transfer positions panel support 76A is parallel to panel support 76B when carriages 72A and 72B are brought together. Carriages 72 may be moved toward one another until a panel supported on panel support 76 A contacts panel support 76B. Carriages 72 may optionally be driven together so that a panel being transferred is compressed between panel supports 76A and 76B with a desired force of compression for at least some period during the transfer of the panel. In some embodiments the carriages are brought together with a force on the order of 1000 N. In some embodiments the carriages are brought together with a force on the order of about 0.1 to 0.5 N/cm ² times the area of the panel being imaged.

[0087] One or both of panel supports 76 may comprise a surface for supporting panels P that is resiliently mounted such that upon bringing panel supports 66 together the surfaces on which a panel P is supported are self- aligning to be parallel to one another. [0088] Because carriages 72 are constrained to follow track 74 panel supports 76A and

76B will always have the same alignment to one another when they are brought together in their transfer positions. Relative positioning of panel supports 76A and 76B in both directions transverse to track 74 (e.g. in vertical and horizontal directions) are fixed by track 74. Parallelism of panel supports 76 is fixed by stops 77D. For example in a case where both carriages 12 run on air bearings on the same pair of granite rails 74 A, 74B the alignment of panel supports 76A and 76B may be repeatable in a transfer to an accuracy of Ι Ομιτι or better.

[0089] Panel supports 76 may optionally comprise alignment features that facilitate repeatable alignment of panel supports 76A and 76B with one another. The alignment features may comprise tapered pins that engage corresponding sockets and/or any of the other alignment features described herein.

[0090] Apparatus 70 may include various design features which facilitate accurate pivoting of panel supports 76 between positions for: panel loading/unloading; panel transfer; and/or panel imaging. By way of non-limiting example a carriage 72 may provide stops that positively define the loading/unloading position, transfer position and/or imaging position.

[0091] Figure 7E schematically shows a carriage 72 with a stop 77D that positively defines the transfer position, a stop 77E that positively defines the imaging position and a stop 77F that positively defines the loading/unloading position. A panel support 76 may be placed in the transfer position by rotating the panel support 76 about axis 77C until the panel support 76 is against positive stop 77D. A panel support 76 may be placed in the imaging position by rotating the panel support 76 about axis 77C until the panel support 76 is against positive stop 77E. A panel support 76 may be placed in the

loading/unloading position by rotating the panel support 76 about axis 77C until the panel support 76 is against positive stop 77F. One or more of the stops may be moved out of the way to allow panel support 76 to pivot past the position defined by the stop to another position.

[0092] Another alternative is to engage a registration pin in a recess to hold a panel support 76 at a desired pivot angle for a particular operation.

[0093] As an alternative to providing positive stops or registration pins for some or all positions of a panel support 76 actuators for pivoting panel supports 76 may have sufficiently precise control over the angle of tilt of panel support 76 to position panel support 76 in the imaging and/or transfer and/or loading position with a desired level of accuracy.

[0094] The transfer of a panel P from panel support 76A to panel support 76B may comprise bringing panel supports 76A and 76B together as described above, so that the panel P is sandwiched between panel supports 76A and 76B with the panel P held to panel support 76A by a vacuum or other panel holding mechanism, turning on a vacuum or other panel holding mechanism on panel support 76B, turning off the vacuum (or other panel holding mechanism) on panel support 76A, and then moving one or both of carriages 72 to separate panel supports 76.

[0095] In some embodiments, panel supports 76A and 76B are aligned to transfer a panel by setting a first one pf panel supports 76A and 76B (the first one could be either or panel supports 76A and 76B) to its transfer position (e.g. by rotating the panel support so that the plane of the panel support is perpendicular to the direction of motion along track 74). The first one of panel supports 76 may be locked in place in the transfer position (e.g. with a locking pin, a brake, control over a positioning actuator such as a stepper motor or servo motor, or the like). The second one of panel supports 76 may then self-align as the panel supports 76 are brought together. Self-alignment may be facilitated by allowing the pivot angle of the second one of panel supports 76A and 76B to 'float' as the panel supports 76 are brought together. Floating may be achieved, for example, by depowering an actuator such as a stepper or servo motor that sets the tilt angle of the second one of the panel supports. In this manner the second one of panel supports 76 will make itself parallel to the other panel support 76 as the two panel supports are brought together to transfer a panel. With the first one of panel supports 76 in a repeatable position prior to transferring a panel any imaging on a first face of the panel will have a repeatable known location relative to the second one of panel supports 76 after the panel is transferred. [0096] In some embodiments one or both of the panel supports 76 also provide resilience which allows slight rotations of panel supports 76 (or at least the surfaces of panel supports 76 that support panel P) about a vertical axis in a plane of the panel. Such resilience may facilitate making the surfaces of panel supports 76 between which a panel P is held to be parallel to one another during transfer of the panel P. The second panel support can approach the first panel support with a small amount of angular play. As it engages with the first panel support it will self align to the angle of the first panel support.

[0097] In some embodiments one or both of the panel supports is compliantly mounted so that when panel supports 76 are driven together into the transfer configuration one or both of the panel supports is slightly displaceable against a bias force provided by one or more springs, resilient pads, gas struts or the like. Providing such a compliant mounting can help to make the force with which a panel is compressed between panel supports 76 consistent and repeatable.

[0098] Apparatus 70 includes an imaging machine 16 located at a known position relative to track 74. For example, imaging machine 16 may be supported by a rigid frame at a fixed location and in a fixed alignment relative to track 74. Imaging machine 16 may be spaced apart from track 74 by a distance such that a panel P supported on a panel support 76 of either carriage 72 can be imaged by imaging machine 16 when the carriage 72 is at a suitable position along track 74.

[0099] When a panel support is in the imaging position, a panel P supported on the panel support may be imaged by moving the corresponding carriage 72 until the panel P is in a known position adjacent to the imaging machine 16. Imaging machine 16 may then be operated to image the accessible face of the panel P. The panel P may then be transferred to the panel support 76 of the other carriage 72. In the transfer the panel is flipped over so that the face of panel P that was previously in contact with the panel support of the first carriage 72 is now accessible. The panel support of the second carriage may then be moved to its imaging position and the second carriage may be moved into position to image the accessible face of panel P using imaging machine 16.

[0100] Figure 7A shows apparatus 70 with panel P loaded on panel support 76A of carriage 72A. An upper first face of panel P has been imaged by imaging machine 16. Figure 7B shows the panel P being transferred to the panel support 76B of a second carriage 72B. Figure 7C shows apparatus 70 imaging a second face of panel P using imaging machine 16. In this process, unimaged panels may be placed onto panel support 76A at one side of apparatus 70 and panels that have been imaged on both sides may be removed from panel support 76B on an opposing side of apparatus 70. [0101] If imaging machine 16 supports imaging in either direction, a first face of a panel may be imaged while carrying the panel on carriage 72 A past imaging machine 16 in one direction and a second face of the panel may be imaged while carrying the panel on carriage 72B past imaging machine 16 in a second direction opposed to the first direction. In other embodiments both faces of the panel P are imaged while the panel is being carried in the same direction past imaging machine 16. [0102] Figure 8 is a flow chart that illustrates a method 80 according to an example embodiment. At block S 10 a panel is loaded onto a panel carrier (e.g. a vacuum table). At block S 12 the panel is moved to a position at which imaging can be commenced (if not already at a position suitable for imaging). At block S14 a first face of the panel is imaged. At block S16 the first and second panel supports are oriented to face one another. At block SI 8 the first and second panel supports are brought together face to face in registered alignment with one another. In block S20 the panel is transferred from the first panel support to the second panel support. In block S22 the panel is moved to a position at which imaging can be commenced and oriented for imaging (if necessary). In block S24 the second face of the panel is imaged. Imaging the second face of the panel may comprise imaging features on the second face of the panel so that the features have desired alignments with corresponding features on the first face of the panel. In block S26 the panel is unloaded.

[0103] In some embodiments panels are loaded onto panel supports 76 from below. In such embodiments panel supports 76 may have a loading/unloading position in which rotation about axis 77C is continued until the panel support 76 is inverted. A stack of unimaged panels may be provided at a suitable location in the path of carriage 72A. For example, in the embodiment of Figures 7 A to 7C the stack of unimaged panels may be provided at a suitable location between members 74 A and 74B. Members 74A and 74B may be spaced apart by a distance somewhat greater than a width of the panels. For example, a machine 70 designed to image panels having widths up to 24 inches (about 31 cm) may have members 74A and 74B spaced apart by about 26 inches (about 36 cm).

[0104] Panel support 76A may be moved to the inverted loading position and then carriage 72A may be positioned over the stack of unimaged panels. The stack may be lifted (e.g. by a suitable actuator) until an uppermost panel is close enough to the inverted panel support 76A to be held by the vacuum or other holding mechanism of panel support 76A. Panel support 76A may then be moved to the imaging position and a first side of the panel may be imaged.

[0105] Preferably the stack of panels is lifted against the inverted panel support 76A with sufficient force to flatten the uppermost panel against the panel support 76A. Vacuum or other holding mechanism may then keep the panel flat.

[0106] To prevent a carriage 72 from being lifted when loading a panel, apparatus 70 may include one or more structures or mechanisms for holding the carriage 72 to track 74. A hold-down may take any of a wide variety of forms including:

· One or more bearings (which may be, for example an air bearing, a roller bearing, a recirculating ball bearing, a pad or a combination of these that bears against a surface which prevents lifting of carriage 72 off of track 74. For example, where track 74 comprises a rail on which carriage 72 is supported by air bearings an air bearing may be provided on the underside of the rail or on an underside of one or more flanges projecting from the rail to prevent lifting of the carriage 72.

• When the carriage 72 is in a loading position a hold-down surface of apparatus 70 may block lifting of the carriage 72 away from track 74. The hold-down surface may engage a top surface of the carriage 72 or a pin or other element projecting from carriage 72 or a slot or groove in a lateral surface of carriage 72, for example. · Apparatus 70 may include an active hold-down that is actuated to hold carriage 72 from lifting off of track 74 when it is being loaded. An example of an active hold- down is an actuator that, when actuated, pushes on carriage 72 in a direction opposed to the forces with which a panel is pressed against a panel support.

Another example of an active hold down is an electromagnet or vacuum system that, when energized, resists the forces with which a panel is pressed against a panel support.

[0107] After a second side of the panel has been imaged, the imaged panel, with both sides imaged, is on panel support 76B. Carriage 72B may be moved to an unloading location along track 74 and panel support 76B moved to its inverted loading/unloading position by rotation about axis 77C. The vacuum (or other holding mechanism) may then be turned off and the panel is then free to fall onto an output stack, output conveyor or other collection area.

[0108] Many other arrangements are possible for loading panels onto panel carrier 76A and/or 76B or unloading panels from panel carriers 76A and/or 76B. For example a robot may be provided to load panels onto and/or unload panels from panel supports 76. [0109] In some embodiments, a panel is placed in position to be imaged by imaging machine 16 and is held stationary as imaging machine 16 operates to image the panel. In other embodiments the panel 16 is moved along track 74 as it is being imaged by imaging machine 16. A panel may be moved along track 74 during imaging by advancing carriage 72 along track 74.

[0110] Any of a wide range of mechanisms may be provided to move carriages 72 along track 74 in the performance of methods for panel imaging. For example:

• A separate positioning mechanism may be provided for positioning each carriage 72;

• A single positioning mechanism that can be selectively coupled to drive either one of carriages 72.

• Two or more positioning mechanisms of different types may be provided. The mechanisms may differ, for example, in speed / precision of positioning or other characteristics. For example, a first faster lower-precision positioning mechanism may be provided in combination with a second higher-precision positioning mechanism. Apparatus 70 may include means for selectively coupling and uncoupling each carriage 72 from either one of the positioning systems.

• In cases where carriages 72 can be disconnected from positioning mechanisms, brakes may be provided to prevent carriages from moving along track 74 when they are not being positioned by a positioning mechanism.

[0111] A positioning mechanism may comprise any suitable mechanism for positioning carriages 72A and/or 72B along track 74. For example, a positioning mechanism may comprise:

• a lead screw (the lead screw may be rotationally fixed and a rotating nut may drive the lead screw or the lead screw may be driven to rotate relative to a nut);

• a ball screw;

• a stepper-motor or servo motor or other rotary actuator connected to advance a carriage 12 by way of a cord or cable or gear drive or the like;

• a linear motor;

• a linear actuator such as a pneumatic cylinder or a hydraulic cylinder; [0112] In some embodiments a positioning mechanism 80 is applied to advance carriages 72 during imaging by imaging machine 16. Positioning mechanism 80 may be controlled by a controller of imaging machine 16. One positioning mechanism may be configured to be temporarily coupled to carriage 72A or carriage 72B so that the same positioning mechanism 80 may move either carriage 72A or carriage 72B along track 74. For example, apparatus 70 may include clamps that can be selectively operated to couple carriage 72A or carriage 72B to positioning mechanism 80. In some embodiments the positioning mechanism 80 is operated to move a panel P in coordination with the operation of imaging machine 16 during imaging of the panel P.

[0113] Figure 7D illustrates one example implementation in which a positioning mechanism 80 comprises lead screw 82A fixed to a frame 82B that is slidably mounted to linear rails 82C that run parallel to track 74. A nut 82D engages the threads of lead screw 82A and is driven to rotate by a motor 82E (e.g. a stepper motor or servo motor). Nut 82D is fixed in position between thrust bearings 82F. When nut 82D is rotated relative to lead screw 82A, frame 82B is driven to travel parallel to track 74.

[0114] One or more clutches may be selectively operated to couple one of carriages 72 to frame 82B so that positioning mechanism 80 may be operated to move the carriage 72 within the range of motion of positioning mechanism 80. In the illustrated embodiment a clutch is provided by a clamp 82G. Clamp 82G may, for example, comprise an electromagnetic clamp. Preferably clamp 82G comprises interlocking surfaces that cause the carriage to have a position relative to frame 82B that is fixed in the longitudinal direction when clamp 82G is engaged. In the illustrated embodiment clamp 82G includes a conical member 83A that engages a complementary recess 83B when clamp 82G is engaged. In some embodiments clamp 82G is mounted on an outrigger projecting from a carriage 72.

[0115] Where one positioning mechanism is provided brakes may be used to hold carriages 72 in position along track 74 when they are not connected to the positioning system (e.g. to positioning system 80). In such embodiments a panel may be transferred from one panel support 76 to another by applying the brake of a first carriage 72 and moving the panel support 76 of the first carriage 72 to the transfer position, coupling the other carriage 72 to positioning mechanism 80 and moving panel support 76 of the second carriage 72 to its transfer position and then operating positioning mechanism 80 to drive the panel support 76 of the second carriage 72 against the panel support 76 of the first carriage 72.

[0116] Some embodiments provide two positioning mechanisms. For example, a positioning mechanism 80 as described above may be combined with a rapid positioning mechanism. The rapid positioning mechanism may be operated to move a carriage 72 to a loading or unloading position along track 74 while positioning mechanism 80 is being used in imaging a plate being carried by the other carriage 72.

[0117] In the exemplary embodiment as illustrated in Figure 7D, a rapid-positioning mechanism 84 comprises a belt 85 driven by a rotary drive 86 (e.g. a stepper motor or servo motor). Belt 85 may comprise a toothed belt such as a timing belt. Each carriage comprises a clamp (86A or 86B) that may be selectively operated to grip belt 85. When clamp 86A is controlled to grip belt 85, motions of belt 85 drive carriage 72A. When clamp 86B is controlled to grip belt 85, motions of belt 85 drive carriage 72B. Either one of carriages 72 may be temporarily coupled to belt 85 such that the carriage 72 may be moved to a desired position along track 74 by circulating belt 85 in a desired direction. A rapid positioning mechanism 84 may be operable to translate carriages 72 along track 74 more rapidly than positioning mechanism 80. Clamps 86 may, for example be actuated electromagnetically, by pressurized fluid or by any other suitable principle of operation.

[0118] Figure 7D shows positioning mechanisms 80 and 84 on either side of carriage 72 for convenience of illustration. Positioning mechanisms may be arranged in other ways, for example,

· side-by side on the same side of track 74;

• stacked above one another on the same side of track 74

• under track 74,

• where track 74 comprises plural rails (e.g. rails 74 A and 74B) between the rails,

• built into track 74,

· etc. [0119] Figure 7F shows an example control system 90 for an imaging apparatus of the type described herein. Imaging machine 16 has access to a data store containing first face image data 17A and second face image data 17B. Data 17A and 17B respectively define patterns to be imaged on first and second faces of a panel. A controller 92 receives inputs from suitable feedback sensors 94 that indicate the state of an imaging system being controlled. Feedback sensors 94 may comprise, for example, linear position encoders, angular position encoders, motor encoders, proximity switches, limit switches, pressure sensors, load cells or the like. Controller 92 controls actuators that operate the imaging system to present faces of panels to imaging machine 16 and triggers imaging machine 16 to image panels using data 17A and 17B. The illustrated embodiment provides: actuators 96A, 96B and 96C which respectively control tilt of a first panel support, position of the first panel support and whether or not vacuum is applied to the first panel support;

actuators 97 A, 97B and 97C which respectively control tilt of a first panel support, position of the first panel support and whether or not vacuum is applied to the first panel support; and an actuator 98 that controls loading of panels onto the first panel support (e.g. by lifting a stack of panels so that a top-most panel can be taken onto a panel support. Control system 90 also includes optional brake actuators 99A and 99B which may be applied to hold a position of carriage 72A and 72B (or other actuator mechanism) respectively. Control system 90 also includes optional clutches 99C which may be operated to couple a carriage 72A and 72B (or other actuator mechanism) to any of one or more positioning mechanisms..

Interpretation of Terms

[0120] Unless the context clearly requires otherwise, throughout the description and the claims:

· "comprise", "comprising", and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of

"including, but not limited to";

• "connected", "coupled", or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof;

• "herein", "above", "below", and words of similar import, when used to describe this specification, shall refer to this specification as a whole, and not to any particular portions of this specification;

• "or", in reference to a list of two or more items, covers all of the following

interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list;

• the singular forms "a", "an", and "the" also include the meaning of any appropriate plural forms.

[0121] Words that indicate directions such as "vertical", "transverse", "horizontal", "upward", "downward", "forward", "backward", "inward", "outward", "vertical", "transverse", "left", "right", "front", "back", "top", "bottom", "below", "above", "under", and the like, used in this description and any accompanying claims (where present), depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly. [0122] Embodiments of the invention may incorporate control systems that are implemented using specifically designed hardware, configurable hardware, programmable data processors configured by the provision of software (which may optionally comprise "firmware") capable of executing on the data processors, special purpose computers or data processors that are specifically programmed, configured, or constructed to perform one or more steps in a method as explained in detail herein and/or combinations of two or more of these. Such software may, for example, be applied to cause a processor in a controller to coordinate operation of the components of an apparatus as described herein.

[0123] Examples of specifically designed hardware that may be included in a controller for apparatus as described herein are: logic circuits, application-specific integrated circuits ("ASICs"), large scale integrated circuits ("LSIs"), very large scale integrated circuits ("VLSIs"), and the like. Examples of configurable hardware are: one or more programmable logic devices such as programmable array logic ("PALs"), programmable logic arrays ("PLAs"), and field programmable gate arrays ("FPGAs")). Examples of programmable data processors are: microprocessors, digital signal processors ("DSPs"), embedded processors, graphics processors, math co-processors, general purpose computers, server computers, cloud computers, mainframe computers, computer workstations, and the like. For example, one or more data processors in a control circuit for a device may implement methods as described herein by executing software instructions in a program memory accessible to the processors. Such computing hardware may, for example, be applied to coordinate the motions of apparatus as described herein and/or to control and/or coordinate operation of an imaging device or aperture-forming device as described herein.

[0124] Processing may be centralized or distributed. Where processing is distributed, information including software and/or data may be kept centrally or distributed. Such information may be exchanged between different functional units by way of a

communications network, such as a Local Area Network (LAN), Wide Area Network (WAN), or the Intemet, wired or wireless data links, electromagnetic signals, or other data communication channel.

[0125] For example, while processes or blocks are presented in a given order, alternative examples may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or subcombinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.

[0126] The invention may also be provided in the form of a program product. The program product may comprise any non-transitory medium which carries a set of computer-readable instructions which, when executed by a data processor, cause the data processor to control apparatus to execute a method of the invention. Program products according to the invention may be in any of a wide variety of forms. The program product may comprise, for example, non-transitory media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, EPROMs, hardwired or preprogrammed chips (e.g., EEPROM semiconductor chips),

nanotechnology memory, or the like. The computer-readable signals on the program product may optionally be compressed or encrypted.

[0127] Where a component (e.g. an alignment ,mechanism, imaging device, controller, processor, conveyor, actuator, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a "means") should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.

[0128] Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions, and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by:

replacing features, elements and/or acts with equivalent features, elements and/or acts; mixing and matching of features, elements and/or acts from different embodiments; combining features, elements and/or acts from embodiments as described herein with features, elements and/or acts of other technology; and/or omitting combining features, elements and/or acts from described embodiments. [0129] It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions, and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.