Stencil printer cover having movable door with closing feature

Abstract

To provide a stencil printer and a method of presenting a stencil or items within a stencil printer.SOLUTION: A cover of a stencil printer is hingedly mounted to a frame, and movable between a closed position and an open position. The cover includes an elongate opening formed therein and a movable door configured to selectively close the elongate opening. The elongate opening is sized to enable the stencil and / or a tooling tray to pass through. A controller is configured to control movement of the movable door between a closed position and an open position. A sensor assembly is proximate the elongate opening. The sensor assembly is coupled to the controller and configured to detect an object within the elongate opening when moving the movable door to the closed position. The sensor is configured to generate a signal to the controller when detecting an object within the elongate opening. The controller, upon receiving the signal from the sensor, is configured to move the movable door to the open position.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This application relates generally to stencil printers and related methods for printing viscous materials, such as solder paste, onto electronic substrates, such as printed circuit boards (PCBs), and more particularly to systems and methods for replacing items in stencil printers. [Background technology]

[0002] In manufacturing surface mount printed circuit boards, a stencil printer can be used to print solder paste onto the circuit board. Typically, a circuit board having a pattern of pads or some other conductive surface onto which the solder paste will be deposited is automatically fed into the stencil printer, and one or more small holes or marks (known as "fiducials") on the circuit board are used to properly align the circuit board with the stencil printer's stencil or screen before printing the solder paste onto the circuit board. In some systems, an optical alignment system embodying a vision system is used to align the circuit board with the stencil.

[0003] In such printers, once the circuit board is properly aligned with the stencil, it is raised up to the stencil and solder paste is dispensed onto the stencil. A wiper blade (i.e., squeegee) traverses the stencil, forcing the solder paste through multiple holes (openings) in the stencil and onto the circuit board. As the squeegee moves across the stencil, the solder paste tends to spread out in front of the blade. This desirably mixes and shears the solder paste to achieve the desired viscosity to facilitate filling the screen or stencil holes. The solder paste is typically dispensed onto the stencil from a standard cartridge. The stencil is then separated from the circuit board, and the majority of the material remains on the circuit board due to the adhesion between the circuit board and the solder paste. The material remaining on the stencil surface is removed in a cleaning process before additional circuit boards are printed.

[0004] Another process in printing circuit boards involves inspecting the circuit board after the solder paste has been deposited on the surface of the circuit board. Inspecting the circuit board is important to determine whether a clean electrical connection can be made. Too much solder paste can cause a short circuit, while too little solder paste in the right location can prevent electrical contact. Typically, a visual inspection system is also utilized to provide two-dimensional or three-dimensional inspection of the solder paste on the circuit board.

[0005] Modern stencil printers require manual intervention to perform routine operations. For example, during changeover, an operator must perform many manual tasks, such as changing stencils, replacing solder paste cartridges, replacing squeegee blades, and replacing support tooling. Each of these tasks requires the operator to perform the task manually. For example, in most stencil printers, the operator must open the stencil printer cover, unlock the stencil, remove the stencil, properly insert the replacement stencil, and lock the replacement stencil in place. Other items, such as squeegee blades, support tooling, and solder paste cartridges, are also subject to replacement. Changeover operations can take as long as 30 minutes, during which the stencil printer is not operational, potentially resulting in an idle PCB production line. Summary of the Invention

[0006] One aspect of the present disclosure relates to a stencil printer for printing assembly material onto an electronic substrate. In one embodiment, the stencil printer includes a frame, a stencil coupled to the frame, the stencil having a hole formed therein, a support assembly coupled to the frame configured to support the electronic substrate in a printing position below the stencil, a printhead gantry coupled to the frame, and a printhead assembly supported by the printhead gantry such that the printhead assembly traverses the stencil during a printing stroke. The printhead assembly includes a printhead having a squeegee blade assembly configured to spread solder paste along the stencil. The stencil printer further includes a cover coupled to the frame to enclose operating components of the stencil printer, including the stencil, support assembly, printhead gantry, and printhead assembly. The cover is hingedly attached to the frame of the stencil printer and movable between a closed position and an open position. The cover includes an elongated opening formed therein and a movable door configured to selectively close the elongated opening. The elongated opening is sized to allow a stencil and / or tooling tray to pass therethrough. The stencil printer further includes a controller coupled to the movable door, the controller configured to control movement of the movable door between a closed position and an open position, and a sensor assembly proximate to the elongated opening. The sensor assembly is coupled to the controller and configured to detect an object within the elongated opening when the movable door is moved to the closed position. The sensor is configured to generate a signal to the controller upon detecting an object within the elongated opening. The controller is configured to move the movable door to the open position upon receiving a signal from the sensor.

[0007] An embodiment of the stencil printer may further include slidably coupling a movable door to the cover frame to allow movement of the movable door relative to the cover between a closed position and an open position. The sensor assembly may include a linear resistive pressure sensor configured to detect a force exerted by an object when engaged with the linear resistive pressure sensor. The sensor assembly may further include a foam laminate or a flexible laminate disposed on the linear resistive pressure sensor. The linear resistive pressure sensor may be coupled to a conversion PCB and configured to generate a pressure sensor feedback interrupt signal when a force exerted by an object is detected. The conversion PCB may be coupled to an automation machine personal computer (PC), a pneumatic control, and a servo / stepper motor controller associated with the movable door. The conversion PCB may be configured to generate signals to the automation machine PC and to the servo / stepper motor controller. A CAN BUS may be provided to enable bidirectional communication between the automation machine PC and the servo / stepper motor controller. The movable door may include a movable door frame and at least one panel secured to the movable door frame. The cover may further include two linear slides attached to a cover frame of the cover. The movable door may further include a mounting bracket secured to the movable door frame of the movable door. The cover may further include a first linear slide secured to the cover frame of the cover on one side of the movable door and a second linear slide secured to the cover frame of the cover on the other side of the movable door. The movable door may further include at least one first mounting bracket secured to the movable door frame of the movable door on one side of the movable door and at least one second mounting bracket secured to the movable door frame of the movable door on the other side of the movable door. The cover may further include a pneumatic interlock assembly for locking the position of the movable door in a closed position. The pneumatic interlock assembly may include a switch for ensuring that the movable door is in the closed position prior to operating the stencil printer.The movable door may be configured to be moved by at least one lift bracket attached to the movable cart. The movable door may include an access panel hingedly attached to a frame of the movable door. The access panel may be configured to be manually operated between an open position and a closed position. The movable door may include an assembly configured to provide resistance to downward movement of the movable door.

[0008] Another aspect of the present disclosure relates to a method of providing a stencil or item in a stencil printer. In one embodiment, the method includes inserting a stencil into an elongated opening in a cover of the stencil printer and / or removing a tooling tray from the elongated opening, closing a movable door configured to close the elongated opening, detecting an object in the elongated opening when the movable door is moved to a closed position, and opening the movable door upon detecting the object.

[0009] An embodiment of the method may further include detecting an object within the elongated opening by generating a signal to a controller of the stencil printer, the controller configured to move the movable door to an open position. Detecting the object within the elongated opening may be performed by a sensor assembly coupled to the controller. The sensor assembly may include a linear resistive pressure sensor configured to detect a force exerted by the object when engaging the linear resistive pressure sensor. The method may further include cushioning the object. The object may be cushioned by a foam laminate disposed on the linear resistive pressure sensor. The linear resistive pressure sensor may be coupled to a converter PCB and configured to generate a pressure sensor feedback interrupt signal upon detecting a force exerted by the object. The converter PCB may be coupled to an automation machine personal computer (PC), a pneumatic control associated with the movable door, and a servo / stepper motor controller associated with the movable door. The converter PCB may be configured to generate a signal to the automation machine PC and a signal to the servo / stepper motor controller. A CAN BUS may be provided to enable bidirectional communication between the automation machine PC and the servo / stepper motor controller.

[0010] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures is represented by a like reference numeral. For clarity, not every component may be labeled in every drawing. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a front view of the stencil printer. [Figure 2] FIG. 2 is a front perspective view of the stencil printer. [Figure 3] FIG. 3 is a top view, with portions removed, of the stencil printer shown in FIG. 2. [Figure 4]1 is a perspective view of a portion of a cover of a stencil printer according to an embodiment of the present disclosure, the cover having a movable door configured to surround a slot, the movable door shown in an open position. [Figure 5] FIG. 5 is a perspective view of a portion of the cover of the stencil printer shown in FIG. 4 with an operator presenting an item to the stencil printer. [Figure 6] FIG. 1 is a perspective view of a portion of the cover of a stencil printer, with the movable door shown in a closed position. [Figure 7] FIG. 7 is a perspective view of a portion of the cover of the stencil printer shown in FIG. 6 with an operator standing in front of the movable door. [Figure 8] FIG. 2 is a perspective view of a stencil printer and a movable cart. [Figure 9] FIG. 9 is a cross-sectional view of the stencil printer and movable cart shown in FIG. 8. [Figure 10] FIG. 1 is a perspective view of a stencil printer. [Figure 11] FIG. 1 is a perspective view of a cover according to an embodiment of the present disclosure. [Figure 12] FIG. 12 is a perspective view of a movable door of the cover shown in FIG. [Figure 13] FIG. 10 is an enlarged perspective view of the movable door interlock assembly, with the movable door shown in the open position. [Figure 14] FIG. 10 is an enlarged perspective view of the movable door interlock assembly, with the movable door shown in the closed position. [Figure 15] FIG. 10 is a perspective view of a mobile cart according to an embodiment of the present disclosure, wherein the mobile cart has a bracket configured to interact with a movable door of a cover. [Figure 16] FIG. 10 is a perspective view of a portion of a movable door of a cover of a stencil printer. [Figure 17] FIG. 10 is an enlarged perspective view of a portion of the movable door of the cover, the movable door being shown in an open position. [Figure 18] FIG. 10 is an enlarged perspective view of a portion of the movable door of the cover, the movable door being shown in a closed position. [Figure 19]FIG. 2 is a perspective view of the movable door showing a handle provided on the movable door. [Figure 20] FIG. 10 is a perspective view of a movable door according to another embodiment of the present disclosure, the movable door being shown in a closed position. [Figure 21] 21 is a perspective view of the movable door of FIG. 20, the movable door being shown in an open position. [Figure 22] 23 is another perspective view of the movable door of FIGS. 20 and 22 from the opposite side of the movable door, with the movable door shown in the open position. FIG. [Figure 23] FIG. 1 is a front perspective view of the stencil printer cover showing the movable door in the closed position. [Figure 24] FIG. 25 is an enlarged rear perspective view of the stencil printer cover and movable door shown in FIG. 24. [Figure 25] FIG. 10 is an enlarged cross-sectional view of a portion of a movable door and an elongated opening with a linear resistive pressure sensor and a foam laminate positioned at the bottom end. [Figure 26] FIG. 10 is a diagram showing a control system for a movable door. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure relates generally to material dispensing machines (referred to herein as "stencil printers," "screen printers," "printers," or "printers") and other equipment utilized in surface mount technology (SMT) process lines and configured to dispense assembly materials (e.g., solder paste, conductive ink, or encapsulant) onto substrates (e.g., referred to herein as "electronic substrates," "circuit boards," "boards," "PCBs," "PCB boards," "substrates," or "PCB plates") or to perform other operations such as inspection, rework, or placement of electronic components onto substrates. Specifically, embodiments of the present disclosure are described below with reference to stencil printers used to fabricate printed circuit boards.

[0013] By way of example only and not limitation, the present disclosure will now be described in detail with reference to the accompanying drawings. The present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The principles described in this disclosure may be used in other embodiments and may be practiced or carried out in various ways. Furthermore, the phraseology and terminology used herein are for purposes of description and should not be considered limiting. Any reference to system and method examples, embodiments, components, elements, or operations referred to in the singular herein can also encompass embodiments that include the plural, and any reference to any embodiment, component, element, or operation referred to in the plural herein can also encompass embodiments that include only the singular. References in the singular or plural are not intended to limit the systems or methods, their components, operations, or elements disclosed herein. The use of the terms "including," "comprising," "having," "containing," "with," and variations thereof herein is meant to encompass the items listed thereafter, as well as equivalents thereof and additional items. References to "or / or" may be construed as inclusive such that any term described with "or / or" may refer to any of one, more than one, and all of the described terms. Additionally, in the event of inconsistencies in the usage of terms between this specification and any document incorporated by reference, the usage of the term in the document incorporated by reference is supplementary to the usage of the specification, and in the event of an inconsistency, the usage of the term in this specification shall control.

[0014] For illustrative purposes, the following embodiments of the present disclosure will be described with reference to a stencil printer used to print assembly materials, such as solder paste, onto circuit boards. However, those skilled in the art will appreciate that the present disclosure is not limited to stencil printers that print solder paste onto circuit boards, but can also be used in other applications requiring the dispensing of other viscous assembly materials, such as adhesives and encapsulants. For example, the device can be used to print epoxies used as underfill for chip-scale packages. Furthermore, the stencil printers of the present disclosure are not limited to those that print assembly materials onto circuit boards, but also include those used to print other materials onto various substrates, such as semiconductor wafers. Additionally, the terms screen and stencil are used interchangeably herein to describe devices within the printer that define the pattern printed on the substrate. In certain embodiments, the stencil printer may include a Momentum™ or Edison™ series stencil printer platform offered by ITW Electronic Assembly Equipment of Hopkinton, Massachusetts. An exemplary stencil printer is generally designated 5 in FIG. 1 . In this embodiment, the stencil printer 5 is a Momentum™ series stencil printer platform offered by ITW Electronic Assembly Equipment of Hopkinton, Massachusetts.

[0015] 2, a stencil printer according to an embodiment of the present disclosure is generally indicated at 10. As shown, the stencil printer 10 has a frame 12 that supports the stencil printer's components, which may include, in part, a controller 14, a display 16, a stencil 18, and a printhead or printhead assembly. The printhead or printhead assembly is generally indicated at 20 and is configured to apply solder paste in a manner described in more detail below.

[0016] As shown in FIG. 2 and described below, the stencil and printhead assembly can be coupled or otherwise connected to frame 12, as appropriate. In one embodiment, printhead assembly 20 can be mounted on printhead assembly gantry 22, which can be mounted on frame 12. Printhead assembly gantry 22 allows printhead assembly 20 to move in the y-axis direction under the control of controller 14 and to engage stencil 18 to apply pressure to the printhead assembly. In one particular embodiment, printhead assembly 20 can rest above stencil 18 and can be lowered in the z-axis direction to contact and sealingly engage the stencil.

[0017] Stencil printer 10 may also have a conveyor system having rails (not shown) for transporting printed circuit boards (sometimes referred to herein as "printed wiring boards," "boards," or "electronic boards") to a printing position within the stencil printer. The rails may be referred to herein as a "tractor feed mechanism." The tractor feed mechanism is configured to feed, load, or otherwise deliver circuit boards to and from a work area of ​​the stencil printer, sometimes referred to herein as a "print nest."

[0018] 3 , the stencil printer 10 includes a support assembly 28 that supports a circuit board 29 (shown in dashed lines). The support assembly 28 elevates and secures the circuit board so that it is stable during printing operations. In certain embodiments, the substrate support assembly 28 can further include a specific substrate support system, such as a rigid support, multiple pins, or flexible tooling, that is positioned below the circuit board when it is in the printing position. The substrate support system can be used in part to support an interior region of the circuit board to prevent bending or warping of the circuit board during printing operations.

[0019] In one embodiment, the printhead assembly 20 can be configured to receive solder paste from a supply source, such as a dispenser, e.g., a solder paste cartridge, that provides the solder paste to the printhead assembly during printing operations. Instead of cartridges, other methods of supplying solder paste can be utilized. For example, the solder paste can be manually deposited between blades or from an external source. Additionally, in certain embodiments, the controller 14 can be configured to control the operation of the stencil printer 10 using application-specific software using a personal computer having a suitable operating system, such as the Microsoft Windows® operating system provided by Microsoft Corporation. The controller 14 can be networked with a master controller used to control a production line for fabricating circuit boards.

[0020] In one configuration, the stencil printer 10 operates as follows: A circuit board 29 is loaded into the stencil printer 10 using conveyor rails. The support assembly 28 raises and secures the circuit board 29 in the printing position. The printhead assembly 20 is then lowered in the z-axis direction until the printhead assembly blade contacts the stencil 18 with the desired pressure. The printhead assembly 20 is then moved in the y-axis direction across the stencil 18 by the printhead assembly gantry 22. The printhead assembly 20 deposits solder paste onto the circuit board 29 through the holes in the stencil 18. Once the printhead assembly has completely traversed the stencil 18 across the holes, the printhead assembly is lifted from the stencil, and the circuit board 29 is lowered back onto the conveyor rails. The circuit board 29 is then released and transported from the stencil printer 10, allowing a second circuit board to be loaded into the stencil printer. To print on the second circuit board 29, the printhead assembly is lowered in the z-axis direction into contact with the stencil and moved across the stencil 18 in the opposite direction to that used for the first circuit board.

[0021] An imaging system 30 can be provided for the purposes of aligning the stencil 18 with respect to the circuit board 29 before printing and inspecting the circuit board after printing. In one embodiment, the imaging system 30 can be disposed between the stencil 18 and the support assembly 28 on which the circuit board is supported. The imaging system 30 is coupled to an imaging gantry 32 for moving the imaging system. In one embodiment, the imaging gantry 32 can be coupled to the frame 12 and have a beam extending between the side rails of the frame 12, providing back and forth movement of the imaging system 30 above the circuit board 29 in the y-axis direction. The imaging gantry 32 can further include a carriage device that houses the imaging system 30 and is configured to move along the length of the beam in the x-axis direction. The structure of the imaging gantry 32 used to move the imaging system 30 is known in the art of solder paste printing. The imaging system 30 is configured to be positioned anywhere below the stencil 18 and above the circuit board 29 to capture images of predetermined areas of the circuit board or stencil, respectively.

[0022] After one or more applications of solder paste to the circuit board, excess solder paste may accumulate on the bottom of the stencil 18, and a stencil wiper assembly, generally indicated at 34, may travel underneath the stencil to remove the excess solder paste. In other embodiments, the stencil 18 may travel above the stencil wiper assembly.

[0023] As mentioned above, stencil printers require manual intervention to replace and / or replenish certain parts. For example, a typical stencil requires replacement after a certain period of time, e.g., four hours. Stencils also require replacement for separate production runs. Additionally, solder paste cartridges, which supply temperature-controlled solder paste to stencil printers, require replacement over time, e.g., within four hours. Separate production runs may require different solder paste materials. Another item requiring periodic replacement is the squeegee blade, which wears out with use. And finally, tooling used to support the substrate at the printing station is replaced when changing from one production run to another.

[0024] In one embodiment, a method for replacing stencils and / or items located on a tooling tray can include providing clean stencils and / or items on a movable cart when a request for new stencils and / or items on the tooling tray is made for a new production run or due to wear on an existing stencil. In the production line, "dirty" or used stencils and / or items are removed from the stencil printer, and "clean" or new stencils and / or items are inserted from the movable cart into the stencil printer and secured for use. The dirty stencils and / or items can then be transported to a cleaning station where the stencils and / or items are cleaned and prepared for reuse. Once cleaned, the stencils and / or items can be transported back to the stencil printer or storage room, where the stencils and / or items can be reused in the same or a different production run.

[0025] An embodiment of the present disclosure relates to a delivery system configured to automate the changeover process for a stencil printer and to perform one or more of the methods described herein. In one embodiment, the delivery system includes a mobile cart configured to engage with the stencil printer and supply and receive replacement and replenishment parts and materials to the stencil printer. For example, the stencil printer can include a docking station configured to receive the mobile cart. The docking station can include an interface that allows the mobile cart to communicate with the stencil printer. A single mobile cart can be configured to include changeover stencils and / or replacement stencils. During changeover, for example, the stencil printer must be reconfigured to produce a different item. Thus, a new stencil can be utilized within the stencil printer to produce a different product.

[0026] The changeover process described herein can be accomplished with a single mobile cart configured to replace and / or replenish each item. In other embodiments, two or more mobile carts can be provided. For example, for stencil changeover, a mobile cart can be configured to support a predetermined number of stencils. The mobile cart and / or stencil printer can be configured to identify stencils, store stencils, transport stencils to and from the stencil printer, inspect stencils, and interface with the stencil printer. The mobile cart can also be configured to remove used parts, such as stencils, from the stencil printer.

[0027] Embodiments of the present disclosure further relate to a delivery system configured to automate the replenishment process for a stencil printer. In one embodiment, the delivery system includes a movable cart configured to engage with the stencil printer and supply and receive replacement and replenishment parts and materials to the stencil printer. For example, the stencil printer can include a docking station configured to receive the movable cart. The docking station can include an interface that allows the movable cart to communicate with the stencil printer. A single movable cart can be configured to carry a changeover stencil and a replacement stencil.

[0028] 4, the stencil printer, generally designated 100, is substantially identical to the stencil printer 10 described above, unless otherwise noted. Stencil printer 100 includes a cover, generally designated 102, hinged to the frame of the stencil printer so as to move from an open position, in which the interior of the stencil printer is accessible, to the illustrated closed position, in which the operating components of the stencil printer described above are enclosed. In one particular embodiment, cover 102 of stencil printer 100 is made from a metal frame 104, each having panels, generally designated 106, embodying a see-through material, such as plexiglass, to allow an operator to view the working components of stencil printer 100 during operation.

[0029] As shown, the cover 102 includes an elongated slot 108 that allows items positioned in the stencil and tooling tray to be inserted and removed from the stencil printer 100. The cover 102 further includes a movable door, generally designated 110, that is slidably mounted along opposite ends of the elongated slot 108 and is sized to surround the elongated slot when in a closed position. The movable door 110 is configured to move up and down relative to the cover. In one embodiment, the movable door 110 includes an access panel 111 hinged to the cover's frame 104 that allows an operator to manually insert and remove items from the stencil printer 100 through the elongated slot 108.

[0030] FIG. 4 shows the access panel 111 of the movable door 110 shown in the open position, allowing items on a tooling tray, such as stencils or squeegee blades and tooling, to be inserted into and removed from the stencil printer. Specifically, when the access panel 111 of the movable door 110 is in the open position, the elongated slot 108 functions as a mail slot, allowing for partially automated exchange of items including stencils, squeegee blades, and tooling. An operator can pass a stencil and / or tooling tray through the elongated slot, and an end effector or tooling loading / unloading mechanism attached to the printhead of the stencil printer 100 retrieves the stencil and / or tooling tray and returns it to the operator. FIG. 5 shows an operator passing an item into the stencil printer 100 through the elongated slot 108, with the access panel 111 shown in the open position.

[0031] During a product changeover, software associated with the stencil printer 100 controller prompts the operator to load or replace the required item(s) and walks the operator through the process step by step. Once loaded and ready to resume production, the stencil printer 100 scans each new item added to verify that the correct item for the print job has been loaded before continuing.

[0032] Figure 6 shows the access panel 111 of the movable door 110 shown in a closed position to enclose the working components of the stencil printer. As described in more detail below, the movable door 110 of the cover 102 may be configured to be lifted by a movable cart (described below) to allow the movable cart to interface with the stencil printer 100 to allow the stencil printer to place or remove printed circuit board (PCB) support tooling, squeegee blades, and / or stencils while maintaining inaccessibility to the interior of the stencil printer from any operator interface. Figure 7 shows an operator standing in front of the movable door 110, with the access panel 111 and movable door shown in a closed position.

[0033] 8 and 9, a mobile cart, generally designated 200, is shown in a docked position relative to the stencil printer 100. As described in more detail below, the mobile cart 200 includes a lift bracket on the front of the mobile cart for lifting the movable door 110 of the cover 102 of the stencil printer 100 to open the movable door. The mobile cart 200 is docked to the stencil printer 100, and the lift bracket on the front of the mobile cart is configured to engage the underside of the movable door 110 of the cover 102. The mobile cart 200 is now powered on, and the door interlock assembly associated with the movable door 110 is disabled. Based on items being added to or removed from the stencil printer 100, the stencil printer's controller determines, for example, which shelf in the mobile cart 200 will align with the stencil shelf in the stencil printer. The mobile cart 200 passively lifts the mobile door 110 in the z-axis direction to the required height, and once in position, the mobile cart is prompted to prepare to receive one or more items to be loaded into or unloaded from the stencil printer 100. For example, when prompted to unload a stencil, the stencil is unloaded in the y-axis direction from the stencil printer 100 directly onto the mobile cart 200, which stores the stencil and then indexes directly in the z-axis to load or unload the next item(s). The next item may be another stencil and / or items such as tooling and / or squeegee blades on a tooling tray, or an empty tooling tray.

[0034] FIG. 10 shows the movable door 110 of the cover 102 of the stencil printer 100 in a maximum or fully open position. In this position, the elongated slot 108 can accommodate up to four shelves of the movable cart 200. Depending on the requirements of the stencil printer, stencil and / or tooling trays can be transferred in or out of the y-axis from the stencil printer 100 to the movable cart 200 or from the movable cart to the stencil printer. The movable cart 200 may be configured to index the shelves of the movable cart in the z-axis to perform the next required operation until the changeover sequence is complete. Once complete, the movable cart 200 is configured to move the shelves supporting the stencil and / or tooling trays in the y-axis to a home position. The movable cart 200 is then configured to move the shelves in the z-axis to the home position to allow the stencil printer 100 to resume production. At this point, the movable door 110 of the cover 102 of the stencil printer 100 is interlocked to protect the operator when the movable door is closed.

[0035] The mobile cart 200 may remain docked to the stencil printer 100 or may be removed once loading or unloading is complete.

[0036] 11 and 12, the cover 102 of the stencil printer 100 is shown being removed from the stencil printer 100. As described and illustrated above, the cover 102 includes an L-shaped frame 104 having ends hingedly attached to the frame of the stencil printer 100 by hinges 112. One portion of the L-shaped frame 104 has a first solid panel 106a, and another portion of the L-shaped frame has a second transparent panel 106b that extends vertically when the cover 102 is in the closed position. In one embodiment, the hinge 112 is mounted at the top rear of the frame of the stencil printer 100 and is attached to a cross member of the frame 104 of the cover 102.

[0037] Referring to FIG. 12 , the movable door 110 is configured to move up and down inside the cover 102. In one embodiment, the movable door 110 includes a rectangular frame 110a having a see-through panel 110b and an access panel 111. As described above, the access panel 111 is hingedly connected to the frame 110a along the bottom edge of the access panel. The cover 102 includes two linear slides, each indicated at 114, one slide attached to the frame 104 of the cover 102 on the inside left-hand side of the cover and the other slide attached to the frame on the inside right-hand side of the cover. The linear slides 114 are attached to the movable door 110 using four mounting brackets, each indicated at 116, allowing the movable door to move vertically up and down inside the cover 102. Specifically, two mounting brackets 116 are secured to the movable door frame 110b on one side thereof and two mounting brackets are secured to the movable door frame on the other side thereof. Each mounting bracket 116 is configured to slide along a linear slide 114 to allow up and down movement of the movable door 110 relative to the cover frame 104.

[0038] 13 and 14 , the cover 102 includes a pneumatic interlock assembly for securing the position of the movable door 110. As shown, the pneumatic interlock assembly includes an interlock latch 120 provided on the movable door 110 and an interlock cylinder 122 provided on the cover 102. The interlock cylinder 122 is configured to releasably lock the interlock latch 120 to secure the movable door 110 in a closed position. The pneumatic interlock assembly further includes a switch transmitter 124 provided on the movable door 110 and a switch receiver 126 provided on the cover 102. The switch transmitter 124 and the switch receiver 126 are provided to ensure that the movable door 110 is in a closed position prior to operating the operating components of the stencil printer 100. In another embodiment, the pneumatic interlock assembly includes a switch provided to detect that the door 110 is in a closed position. In one example, the switch may be a plunger-type switch.

[0039] 15 and 16 , as previously described, the mobile cart 200 includes two lift brackets, each designated 130, located at the front of the mobile cart and configured to engage the underside of the movable door 110 of the cover 102. Although located at the front of the mobile cart 200, the two lift brackets 130 may be positioned and / or arranged relative to the mobile cart in any desired manner that is convenient for lifting the movable door 110. When the mobile cart 200 is docked to the stencil printer 100, the two lift brackets 130 are positioned to slide under the bottom lip 132 of the frame 110 a of the movable door 110 shown in FIG. Once the mobile cart 110 is initialized and begins to move the vertical shelves on the mobile cart to align with the stencil shelves in the stencil printer 100, the two brackets 130 passively lift the mobile door 110, thereby allowing the appropriate stencil and / or tooling trays to be loaded into or loaded out of the stencil printer onto the mobile cart, as the case may be.

[0040] 17 and 18, the access panel 111 of the movable door 110 is shown open in FIG. 17 and closed in FIG. 18. A hinge 134 is provided to allow movement of the movable door access panel 111 between the open and closed positions. The hinge 134 is fixed to the frame 110a of the movable door 110 and to the access panel 111. A similar hinge is provided on the opposite side of the access panel. Further shown are operating members of the movable door 110, including the interlock latch 120 and interlock cylinder 122, as well as the switch transmitter 124 and switch receiver 126.

[0041] 19, an operator can open or close the access panel 111 of the movable door 110 by using a handle 136 provided on the outer surface of the access panel. Manual operation of the access panel 111 of the movable door 110 can only occur when switching is initiated and the pneumatic interlock assembly is disengaged. Once this task is performed, the access panel 111 of the movable door 110 can be opened, thereby disconnecting the switch. Once the access panel 111 of the movable door 110 is opened, the stencil printer 100 is effectively rendered inoperable until the switch is closed.

[0042] 20-22, in another embodiment, a stencil printer cover 150 includes an elongated slot 152 and a movable door 154 slidably attached to the cover and movable between a closed position (FIG. 20) and an open position (FIG. 21). FIG. 22 shows the opposite side of the movable door 154, with the door shown in the open position. The structure of the stencil printer cover 150 and movable door 154 is similar to the assembly of the cover 102 and movable door 110 shown and described above. The movable door 154 is configured to move up and down automatically, either by an operator or by the stencil printer's controller.

[0043] As shown in FIG. 22 , the movable door 154 is secured to the stencil printer cover 150 by a first set of anchor brackets secured to the cover, with one anchor bracket 156 secured to the cover on one side of the elongated slot 152 and the other anchor bracket 158 ​​secured to the cover on the opposite side of the elongated slot. Each bracket 156, 158 of the first set of anchor brackets includes a vertically mounted cylinder 162, 164, respectively. Each cylinder 162, 164 is guided by a vertically mounted door guide or retainer 166, 168, respectively. Attached to the movable door 154 is a second set of brackets attached to the cylinder shafts of the cylinders 162, 164 to drive the door's up and down movement, with one bracket 170 secured to the door on one side and the other bracket 172 secured to the door on the opposite side.

[0044] The movable door 154 further includes a rack and pinion damped rotating assembly 180 so that the door returns to a home (closed) position when the door is lifted. In other words, the movable door is free to move upward or in the open direction, but when moved downward or in the closed direction, the rack and pinion damped rotating assembly 180 provides resistance to the downward movement of the movable door, preventing it from slamming shut.

[0045] To open the movable door 154, an operator (or software associated with the stencil printer's controller) issues a command to open the movable door. In one embodiment, the operator can enter the command on a graphic user interface (GUI) associated with the stencil printer's display. When this occurs, the stencil printer is inhibited when the sensor / switch 174 is disengaged from the movable door 154. The movable door 154 is secured in a closed position, closing access to the elongated slot 152, by an interlock assembly 176 and the sensor / switch 174.

[0046] While systems such as light curtains or camera monitoring have been used to protect operators from engagement with pinch points attached to moving parts of stencil printers, including moving doors, such systems have drawbacks related to cost and proximity to pinch points, and accidental false triggering can disrupt normal operation of automated machinery. Embodiments of the present disclosure relate to systems used to protect operators.

[0047] 23 and 24 , the stencil printer cover 150 is shown with the movable door 154 in the closed position. An embodiment of the present disclosure relates to a sensor assembly configured to detect the presence of an object in the elongated slot 152 when the movable door 154 is closed. As best shown in FIG. 24 , the elongated slot 152 has a linear resistive pressure sensor 300 mounted at a bottom end 302 of the elongated slot. In one embodiment, the linear resistive pressure sensor 300 is manufactured by Spectra Symbol and sold under the model name ThinPot™. In some embodiments, the linear resistive pressure sensor 300 may be positioned around the entire end of the elongated slot 152, rather than just at the bottom end 302 of the elongated slot. The linear resistive pressure sensor 300 is configured to detect the presence of an object, such as a human finger or hand, when the movable door 154 is closed. As described in more detail below, linear resistive pressure sensor 300 is coupled to a controller, such as controller 14, and is configured to generate a signal to the controller that an object is preventing movable door 154 from closing.

[0048] The sensor assembly further includes a foam laminate strip material 310 secured by an adhesive strip to the linear resistive pressure sensor 300 on the bottom end 302 of the elongated slot 152. In one embodiment, the foam laminate 310 is manufactured by McMaster Carr and sold under model number 93275k121. While a foam material is described, the laminate may be made from a suitable soft durometer material, such as a soft gel or rubber material. In some embodiments, the foam laminate 310 may be secured around the entire end of the elongated slot 152, rather than just the bottom end 302 of the elongated slot. The foam laminate 310 provides an additional layer of protection to protect body parts, such as a person's fingers or hand, from being crushed or otherwise injured between the engagement portion of the movable door 154 and the bottom end 302 of the elongated slot 152 when the movable door is closed. In some embodiments, the movable door 154 is a solid structure or includes a solid frame sized and configured to engage a solid frame that defines the elongated slot 152. Thus, the inclusion of the foam laminate 310 provides a buffer or space to protect a person if their hand or fingers are pinched during movement of the movable door 154 to the closed position.

[0049] 25, the movable door 154 is in a closed position, clearly showing the foam laminate 310 extending along the bottom edge 302 of the elongated slot 152. The bottom edge 302 of the movable door 154 is shown spaced apart from the foam laminate 310, with the linear resistive pressure sensor 300 positioned below the foam laminate. The thickness of the foam laminate 310 may be increased or decreased depending on the amount of force used to close the movable door 154.

[0050] Referring to FIG. 26, a simplified control scheme for the operation of linear resistive pressure sensor 300 is shown. Linear resistive pressure sensor 300 is coupled to a conversion printed circuit board or PCB 320, which is coupled to an automation machine personal computer (PC) 322 (same as controller 14), an air pressure control 324 associated with movable door 154, and a servo / stepper motor controller 326 associated with the movable door. As shown, when linear resistive pressure sensor 300 is pressed by an object such as a human hand or finger, it generates a pressure sensor feedback interrupt signal 330 to conversion PCB 320, which in turn generates a signal 332 to automation machine PC 322 and a signal 334 to servo / stepper motor controller 326, respectively. Automation machine PC 322 is configured to generate a signal 336 to air pressure control 324, and servo / stepper motor controller 326 is configured to generate another redundant signal 338 to air pressure control 324. A CAN BUS 328 is provided to allow two-way communication between the automated machine PC 322 and the servo / stepper motor controller 326 .

[0051] A method for controlling the movement of the movable door 154 is provided to ensure proper movement of tooling into and out of the stencil printer. An elongated opening 152 in the stencil printer's stencil cover is used for loading and unloading stencils and tooling on tooling trays into and out of the stencil printer. The movement of these items can create hazards such as crushing or pinch points for extremities (e.g., a person's fingers, hand, or wrist) if an unexpected or accidental command is made to close the movable door 154 with the extremities in the path of the movable door.

[0052] The sensor assembly described herein can be used to provide real-time monitoring of pinch or crush hazards attached to the movable door 154, which, when closed, eliminates access to moving parts within the stencil printer. The sensor assembly utilizes a pressure-sensitive resistive element laminated with a soft foam coating, embodying a foam laminate 310 configured to conform to the shape of a hand. This conformability helps eliminate injury, while in parallel, the linear resistive pressure sensor 300 is connected to a primary circuit that converts the resistive signal into a logic level signal with redundant monitoring by the stencil printer's controller and motion control system via CAN BUS 328, preventing any movement within the stencil printer. Additionally, the sensor assembly prevents any further commands from being issued by the stencil printer's controller until the hazard is removed. In one embodiment, the primary circuit also has an interrupt tied directly to the pneumatic controller 324 that opens the door upon detection of any object less than 1 / 2 millimeter thick with less than 3.5 ounces of force to eliminate any propagation delay in the main communication circuit. This redundant system works in parallel with the standard interlock that monitors any unwanted entry into the stencil printer.

[0053] Various controllers, such as controller 14 and / or conversion PCB 320, can perform the various operations discussed above. Using data stored in associated memory and / or storage, the controller can execute one or more instructions stored on one or more non-transitory computer-readable media that the controller may comprise and / or be coupled to, which may result in data manipulation. In some examples, the controller can include one or more processors or other types of controllers. In one example, the controller is or includes at least one processor. In another example, the controller performs at least some of the operations discussed above using application-specific integrated circuits tailored to perform specific operations in addition to or instead of a general-purpose processor. As illustrated by these examples, examples according to the present disclosure can perform the operations described herein using many specific combinations of hardware and software, and the present disclosure is not limited to any particular combination of hardware and software components. Examples of the present disclosure may include computer program products configured to perform the methods, processes, and / or operations discussed above. The computer program product may be or may include one or more controllers and / or processors configured to execute instructions for performing the methods, processes, and / or actions discussed above.

[0054] Having thus described several aspects of at least one embodiment, it will be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of this disclosure. Accordingly, the foregoing description and drawings are by way of example only.

Claims

1. 1. A stencil printer for printing assembly material onto an electronic substrate, comprising: The frame and a stencil coupled to the frame, the stencil having holes formed therein; a support assembly coupled to the frame, the support assembly configured to support the electronic substrate in a printing position below the stencil; a printhead gantry coupled to the frame; a printhead assembly supported by the printhead gantry such that the printhead assembly is configured to traverse the stencil during a printing stroke, the printhead assembly including a printhead having a squeegee blade assembly configured to spread solder paste along the stencil; a cover coupled to the frame to enclose operational members of the stencil printer, including the stencil, the support assembly, the printhead gantry, and the printhead assembly, the cover being hingedly mounted to the frame of the stencil printer and movable between a closed position and an open position, the cover including an elongated opening formed therein and a movable door configured to selectively close the elongated opening, the elongated opening being sized to allow the stencil and / or tooling tray to pass therethrough; a controller coupled to the movable door, the controller configured to control movement of the movable door between a closed position and an open position; a sensor assembly proximate the elongated opening, the sensor assembly coupled to the controller and configured to detect an object within the elongated opening when the movable door is moved to the closed position; Equipped with the sensor is configured to generate a signal to the controller upon detecting an object within the elongated opening; The controller is configured to move the movable door to the open position upon receiving the signal from the sensor. Stencil printer.

2. The stencil printer of claim 1 , wherein the movable door is slidably coupled to the cover frame to allow movement of the movable door relative to the cover between the closed position and the open position.

3. 3. The stencil printer of claim 2, wherein the sensor assembly includes a linear resistive pressure sensor configured to detect a force exerted by the object when engaging the linear resistive pressure sensor.

4. The stencil printer of claim 3 , wherein the sensor assembly further comprises a foam or soft laminate disposed over the linear resistive pressure sensor.

5. 4. The stencil printer of claim 3, wherein the linear resistive pressure sensor is coupled to a conversion PCB and configured to generate a pressure sensor feedback interrupt signal upon detecting a force exerted by the object.

6. 6. The stencil printer of claim 5, wherein the conversion PCB is coupled to an automatic machine personal computer (PC), a pneumatic control unit, and a servo / stepping motor controller attached to the movable door.

7. 7. The stencil printer of claim 6, wherein the converter PCB is configured to generate signals to the automated machine PC and to the servo / stepper motor controller.

8. 8. The stencil printer of claim 7, wherein a CAN BUS is provided to enable bidirectional communication between the automated machine PC and the servo / stepping motor controller.

9. The stencil printer of claim 2 , wherein the movable door includes a movable door frame and at least one panel secured to the movable door frame.

10. 10. The stencil printer of claim 9, wherein the cover further includes two linear slides mounted to the cover frame of the cover, and the movable door further includes a mounting bracket secured to the movable door frame of the movable door.

11. 11. The stencil printer of claim 10, wherein the cover further includes a first linear slide fixed to the cover frame of the cover on one side of the movable door, and a second linear slide fixed to the cover frame of the cover on the other side of the movable door.

12. 12. The stencil printer of claim 11, wherein the movable door further includes at least one first mounting bracket secured to the movable door frame on one side of the movable door, and at least one second mounting bracket secured to the movable door frame on the other side of the movable door.

13. The stencil printer of claim 2 , wherein the cover further includes a pneumatic interlock assembly for fixing the position of the movable door in the closed position.

14. 14. The stencil printer of claim 13, wherein the pneumatic interlock assembly includes a switch for ensuring that the movable door is in a closed position prior to operating the stencil printer.

15. 10. The stencil printer of claim 1, wherein the movable door is configured to be moved by at least one lift bracket attached to a movable cart.

16. 10. The stencil printer of claim 1, wherein the movable door includes an access panel hingedly mounted to a frame of the movable door, the access panel configured to be manually operated between an open position and a closed position.

17. The stencil printer of claim 1 , wherein the movable door includes an assembly configured to provide resistance to downward movement of the movable door.

18. 1. A method of passing stencils or items through a stencil printer, comprising: inserting the stencil into an elongated opening in a cover of the stencil printer and / or removing a tooling tray from the elongated opening; closing a movable door configured to close the elongated opening; detecting an object within the elongated opening when the movable door is moved to the closed position; upon detecting the object, opening the movable door; A method comprising:

19. 20. The method of claim 18, wherein detecting the object within the elongated opening includes generating a signal to a controller of the stencil printer, the controller configured to move the movable door to the open position.

20. 20. The method of claim 19, wherein detecting the object within the elongated opening is performed by a sensor assembly coupled to the controller.

21. 21. The method of claim 20, wherein the sensor assembly includes a linear resistive pressure sensor configured to detect a force exerted by the object when engaged with the linear resistive pressure sensor.

22. 22. The method of claim 21, further comprising buffering the object.

23. 23. The method of claim 22, wherein the object is cushioned by a foam laminate disposed over the linear resistive pressure sensor.

24. 22. The method of claim 21, wherein the linear resistive pressure sensor is coupled to a transducer PCB and configured to generate a pressure sensor feedback interrupt signal upon detecting a force exerted by the object.

25. 25. The method of claim 24, wherein the conversion PCB is coupled to an automatic machine personal computer (PC), a pneumatic control attached to the movable door, and a servo / stepper motor controller attached to the movable door.

26. 26. The method of claim 25, wherein the converter PCB is configured to generate signals to the automated machine PC and to the servo / stepper motor controller.

27. 27. The method of claim 26, wherein a CAN BUS is provided to allow bidirectional communication between the automated machine PC and the servo / stepper motor controller.

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