Systems and methods for vibration reduction in encoder-based galvometer

Abstract

An encoder-based galvanometer system is adapted for reducing vibrations within a galvanometer by placing structural elements and a vibration reducing damping material within an encoder. The disclosed systems and methods provide positioning error reduction and improved dynamic performance for encoder-based galvanometer systems.

Description

[0001] priority

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 544,542, filed October 17, 2023, the entirety of which is incorporated herein by reference for all purposes. Background Technology

[0003] This invention relates generally to galvanometers, and more particularly to encoder-based galvanometers.

[0004] Encoder-based galvanometer applications are becoming increasingly demanding, particularly for through-hole drilling applications. In through-hole drilling, printed circuit board assemblies (PCBAs) can have thousands of holes per workpiece. The workload for such laser drilling applications typically exceeds 1000 holes per second. Therefore, the time taken for each hole to reach its target position, or the settling time, has become a crucial metric for galvanometer performance.

[0005] Therefore, state-of-the-art galvanometers must be able to rapidly accelerate the mirror to the indicated position and stabilize within a specified accuracy before a laser can be fired to drill. The stabilization time depends on numerous resonant frequencies of the mechanical system, whose response to acceleration of the indication can cause positioning errors outside the desired time window.

[0006] While some existing galvanometer systems can use damping within the galvanometer to dampen vibrations, it is equally important not to negatively impact the stiffness required for rapid acceleration.

[0007] Therefore, there is still a need for a more efficient and economical encoder-based galvanometer system that provides improved stabilization time without negatively impacting other aspects of the galvanometer and encoder system performance, including, for example, rotor responsiveness, inertial constraints, and encoder accuracy. Summary of the Invention

[0008] According to one aspect, the present invention provides an encoder system for a galvanometer, the encoder system comprising: a transmitter system including at least one transmitter for providing light; a detector system including at least one detector for detecting light; an encoder disk coupled to a rotor of the galvanometer; a rigid structure positioned between the transmitter system and the detector system such that light can pass through the rigid structure; and a damping system comprising at least a polymer material positioned to contact either the transmitter system or the detector system.

[0009] According to another aspect, the present invention provides a galvanometer system comprising: a stator system; a rotor within the stator system; and an encoder system comprising: a transmitter system including at least one transmitter for providing light; a detector system including at least one detector for detecting light; an encoder disk coupled to the rotor of the galvanometer; and a damping system comprising at least one polymer material positioned to contact either the transmitter system or the detector system.

[0010] According to another aspect, the present invention provides a method for operating a galvanometer, the method comprising the steps of: causing a rotor to rotate within a stator; causing an encoder disk of an encoder system to rotate with the rotor, the encoder disk being coupled to the rotor and housed within the encoder system, the encoder system including a transmitter system, a detector system, and the encoder disk; and damping vibrations generated within the encoder system using at least a polymer material positioned to contact either the transmitter system or the detector system. Attached Figure Description

[0011] The following description can be further understood with reference to the accompanying drawings, in which: Figure 1 An illustrative cross-sectional view of a system according to one aspect of the invention is shown; Figure 2 It shows that according to Figure 1 An illustrative cross-sectional view of the system under operating configuration; Figure 3 An illustrative isometric exploded view of a sub-component of the encoder of the present invention is shown; Figure 4 An illustrative isometric view of one aspect of the invention is shown; Figure 5 An illustrative isometric view of another aspect of the invention is shown; Figure 6A and Figure 6B Isometric view ( Figure 6A ) and top view ( Figure 6B This shows an illustrative schematic view of an installation spacer according to one aspect of the invention; Figure 7A and Figure 7B Isometric view ( Figure 7A ) and top view ( Figure 7B This shows an illustrative schematic view of a mounting spacer according to another aspect of the invention; Figure 8A and Figure 8B From above ( Figure 8A ) and from below ( Figure 8BThe isometric view depicts an illustrative schematic view of a galvanometer rotor subassembly according to one aspect of the invention; Figure 9 An illustrative partially exploded view of one aspect of the invention is shown, depicting an encoder subassembly with an encoder disk mounted to a rotor.

[0012] The accompanying drawings are shown for illustrative purposes only. Detailed Implementation

[0013] According to various aspects, the present invention provides systems and methods for more efficient and economical encoder-based galvanometer systems that provide improved stabilization time without negatively impacting the performance of the galvanometer system and encoder system, including, for example, rotor responsiveness, inertial constraints, and encoder accuracy.

[0014] The applicant has discovered that certain errors in encoder-based galvanometer systems are caused by vibrations within and / or the encoder structure, and that these errors can be mitigated through various mechanical means to achieve optimal performance. Some of these means of mitigating vibration errors typically involve the selection of materials for the mechanical structure and the design of the geometry to isolate critical optical components from the remaining moving parts of the galvanometer that cause vibrations.

[0015] According to one aspect, the present invention provides a method for reducing vibration within an encoder-based galvanometer by means of the geometry and placement of structural elements and dampers within the encoder. Systems of various aspects of the present invention provide reduced positioning errors and improved dynamic performance for encoder-based galvanometers.

[0016] The systems of various aspects of this invention offer improved dynamic performance and have applications in markets such as via-hole drilling (VHD); this enables such systems to potentially drive faster with higher power. Mechanical innovations in certain aspects of this invention further enable forward compatibility of the galvanometer with new servo drives capable of delivering greater power. Another benefit of certain aspects of the system includes providing galvanometer designs with higher mechanical stability, achieving greater accuracy for a wider range of applications across other uses. Additionally, some of the vibration reduction methods described herein can be applied to other galvanometer designs.

[0017] According to some aspects, the present invention provides a method in which vibration errors associated with the encoder of a galvanometer are mitigated by placing a viscoelastic material at selected sites within the encoder assembly. Figure 1 and Figure 2 An example of this type of encoder is shown in the figure. Figure 1 A cross-sectional view of an encoder-based galvanometer system 100 including vibration damping according to one aspect of the invention is shown, and Figure 2 A system is illustrated where light is emitted and detected. System 100 includes a detector board (detector PCBA) 140, which includes a window 302 (e.g., Figure 2 As shown), light 310 from the transmitter board (transmitter PCBA) 120 passes through the window to reach the encoder disk 150, which rotates with the rotor 170 in the motor assembly 160 of the galvanometer system 100.

[0018] Figure 1 A cross-sectional view shows the encoder side of the galvanometer, where a cover 110 closes and protects the encoder hardware. A transmitter plate 120 is securely mounted on an integrated spacer 130 at a specific focal distance from the encoder disk 150 to prevent movement relative to both the detector plate 140 and the encoder disk 150. The encoder disk 150 is a glass disk with graduated optical marks for detecting angular positions. The motor assembly 160 includes a stator and a housing, and a rotor rotates within the stator. Damping is provided by an elastomeric disk 180 (for the encoder disk), an elastomeric disk 190 (on the top luminous side of the transmitter plate), and an elastomeric component 200 (on the bottom luminous side of the transmitter plate).

[0019] A detector plate 140 is mounted on a motor assembly 160, and an emitter plate 120 is mounted on an integrated spacer 130 within a housing cover 110. An elastomeric material 190 is located on the emitter side of the emitter plate 120 between the emitter plate 120 and the integrated spacer 130. The elastomeric material 190 includes a window 300 through which light passes, and the integrated spacer 130 also provides a window 301 through which light passes. Elastomeric material 300 is disposed on the opposite (top) side of the emitter plate 120 between the emitter plate 120 and the cover 110. An elastomeric disk material 180 is also disposed on the non-reflective side of the detector plate 140.

[0020] Light passes through the emitter plate 120 and is concentrically arranged. Above the detector plate 140 is the emitter plate 120 and has an opening, referred to herein as detector plate window 302, which receives light from LEDs 121, 122, 123, and 124 located on the emitter plate 310. Figure 3 The emitted light 310 (not visible and shown in outline) can be projected through the detector plate window onto the optically patterned encoder disk 150 on the encoder end of the galvanometer rotor 170. The light projected onto the optically patterned encoder disk 150 is then reflected back to the photodetectors 141, 142, 143, 144 of the detector plate (as shown in outline). Figure 3 (As shown), to encode the precise angular position of rotor 170.

[0021] Figure 2 The cross-sectional view shows the encoder side of the galvanometer, depicting the optical path and showing the opening 300 in the bottom elastomer 190 through which light passes from the emitter. Figure 2 An opening 301 through which light passes from the emitter in the integrated spacer 130 is also shown, as is an opening 302 through which light passes from the emitter in the detector plate 140. Figure 2 Light 310 emitted from the transmitter is also shown, which is reflected off the encoder disk and detected by the detector.

[0022] The position of the transmitter plate 120 is designed to be stationary and without any vibrational displacement relative to the detector plate 140, so as not to introduce errors in the angular position of the encoder disk 150. Therefore, this relative position between the transmitter plate and the detector plate is controlled by a rigid support between them (referred to herein as the integrated spacer 130) and elastomeric damping material fastened and compressed at the top 200 and bottom 190 of the transmitter plate 120. The elastomeric material at the top of the transmitter plate 200 is compressed against the inner top of the encoder cover 110 to secure it in place and allow the elastomeric material to absorb vibrational energy from the cover and / or the transmitter plate. The elastomeric material at the bottom of the transmitter plate 190 is compressed and fastened in place between the transmitter plate and the integrated spacer 130.

[0023] The integrated spacer 130 serves a dual purpose: it supports the transmitter plate at a precise optical distance from the encoder disk and, against the bottom of the transmitter plate, firmly secures and compresses the elastomeric material beneath it. To achieve the latter purpose, the integrated spacer 130 incorporates support platforms 132 or components 133 at precise heights to secure the elastomeric material in place and absorb vibrational energy from the transmitter plate. The elastomeric material at the bottom of the transmitter plate 190 also has openings or windows 300 through which light emitted from LEDs 121, 122, 123, and 124 can pass and illuminate the encoder disk 150. Similarly, the integrated spacer 130 and the detector plate 140 each have openings or windows 301 and 302 through which light emitted from LEDs 121, 122, 123, and 124 can pass and illuminate the encoder disk 150.

[0024] Figure 3The encoder sub-assemblies are shown in an exploded view, showing the relative positions of the integrated spacers with respect to the transmitter and detector boards, wherein LEDs 121, 122, 123, 124 (not visible and therefore shown in outline) are mounted to the bottom of the transmitter board 120, and photodetectors 141, 142, 143, 144 are mounted to the bottom of the detector board 140 (not visible and therefore shown in outline). Figure 4 A sub-component of the encoder is shown, illustrating the position of the bottom elastomer 190 relative to the integrated spacer. Figure 4 Also shown are a transmitter plate 120 (shown in outline for clarity) and a detector plate 140, wherein a triangular elastomer member 190 is shown having a hole in its center and is positioned at the bottom of the transmitter plate 120 within an integrated spacer 130.

[0025] Figure 5 A sub-assembly of the encoder is shown, illustrating the position of the top elastomer 200 on top of the transmitter plate 120 (again shown in outline for clarity), which is mounted on an integrated spacer opposite to the detector plate 140. Figure 6A and Figure 6B An integrated mounting spacer 130 for an encoder PCBA is shown, utilizing a single rigid component that occupies minimal volume and provides rigidity. The integrated mounting spacer 130 includes individual spacer posts 131 integrally formed with a structural member 132. Three spacer posts 131 are shown, but those skilled in the art will understand that the number and relative positions of the spacer posts 131 need not be so limited. The structural member 132 acts as a damper on which a platform can be mounted.

[0026] Figure 7A and Figure 7B An alternative integrated mounting spacer 130' is shown, which includes a single rigid member having a structural member 133' connecting a separate spacer post 131' to which a damper can be mounted. Figure 8A and Figure 8B A subassembly having a galvanometer rotor 170, an encoder disk 150, and a damper 180 is shown, wherein the damper includes an elastomeric disk damper mounted to the non-optical side of the encoder disk. Figure 9 The encoder subassemblies are shown in a partially exploded view, showing the relative positions of the encoder disk mounted to the rotor 150 with the detector plate 140 and photodetectors 141 and 142 (shown in outline, with photodetectors 143 and 144 obstructed from view).

[0027] Systems according to various aspects of the invention can dampen vibrations within an encoder-based galvanometer, thereby improving stability and / or positioning accuracy for step lengths of various indications. The dampers described herein are placed in specific areas to target vibrations within the encoder that are associated with the natural frequencies of the main components. These placement areas include the encoder cover, the transmitter PCBA, and the encoder disk mounted on the rotor.

[0028] Suitable damping materials for elastomers 190, 200, and 180 can include a variety of viscoelastic materials, which are subsets of polymers and possess both elastic and viscous properties. The elastic properties allow the material to maintain its shape after absorbing vibrational energy. Some specific material candidates for this design include, but are not limited to: neoprene, silicone, polyurethane, and Sorbothane® materials sold by Sorbothane, Inc., Kent, OH. Any number of these materials can be combined to achieve a beneficial effect. Alternatively, vibration damping can also be achieved by using a viscous fluid if it can be included. Another possible option may include the use of an expandable polymer foam that can be injected into the encoder cover; the exact placement of the damping material will require careful control.

[0029] The damping material is placed in three main areas within the encoder, areas of concern due to vibrations that cause errors. These three main areas include the encoder cover 110, the transmitter PCBA 120, and the encoder disk 150 mounted to the rotor 170. Placing material in any of these main areas can be effective if sufficient surface contact is achieved between the damping material, these components, and the relatively rigid surface mechanically grounded to the more stable part of the galvanometer. The damping material can achieve this by being a single component or separate components, distributed in any number on the surface area to be treated.

[0030] Vibration damping components can be cut or molded into any number of shapes to achieve a particular benefit. They can also be shaped in such a way that the assembly becomes more reliable by avoiding interference with other critical components in the assembly. They can also be shaped or formed in such a way that assembly is facilitated. For example, some molded components may provide ridges, grooves, or press-fit features to allow for more precise placement during manual assembly, which would otherwise be displaced during the remainder of the assembly process.

[0031] The advantage of providing damping material within the encoder is that it provides a faster stabilization time for mirror positioning, and thus improves the overall dynamic performance of the galvanometer in laser steering applications. According to various aspects, the present invention provides an encoder for a limited-rotation motor, wherein a vibration damper is placed between the non-emitting side of a perforated circuit board acting as a transmitter and the inner surface of a protective cover for the encoder. The vibration damper may be made of one or more viscoelastic materials with a hardness between about 30 Shore 00 and about 90 Shore 00, and preferably between about 40 Shore 00 and about 70 Shore 00. The viscoelastic material may have a thickness between about 1.5 mm and about 4 mm, and preferably between about 2 mm and about 3 mm. The vibration damper may be provided by one, two, or more individual parts and may have an integrated feature that allows it to be attached within its assembly without dislodging. In particular, the integrated feature may include a set dimension that allows the vibration damping material to fit tightly within an opening in the receiving surface of either the transmitter printed circuit board or the detector printed circuit board. Vibration dampers can also have the same integrated feature that allows them to self-align within their components by providing a receiving surface that allows the vibration damping material to fit tightly within the receiving surface (e.g., the printed circuit board of a transmitter or detector).

[0032] According to another aspect, the present invention provides an encoder for a finite-rotation motor, wherein a vibration damper is disposed between the light-emitting side of a perforated circuit board acting as a transmitter and a surface that is part of a rigid structure intended to constrain the transmitter relative to a detector. The vibration damper may be made of one or more viscoelastic materials. The vibration damper may be formed from one or more individual parts as discussed above and may be positioned such that light can pass through, for example, a circular aperture from the light-emitting side of the perforated circuit board. The vibration damper may also include integrated features that allow it to attach within its assembly without dislodging, and may include integrated features that allow it to self-align within its assembly.

[0033] According to another aspect, the present invention provides a rigid structure, which is a single solid component placed between a transmitter and a detector and has three or more support points on which a perforated circuit board is mounted. The rigid structure can be provided as an integrated platform supporting a vibration damper, and the vibration damper can be formed of an elastomeric material. The rigid material can be machined from a single sheet of metal or cast from a single sheet of metal. The rigid material, placed between the transmitter and the detector, can include three or more perforated circuit board (PCB) spacers joined by two or more structural members between the spacers. The rigid structure may also include structural members between the two or more PCB spacers supporting the vibration damper.

[0034] According to another aspect, the present invention provides an encoder for a finite-rotation motor, wherein a vibration damper is mounted to the non-optical side of an encoder disk on which the rotor is mounted. Similarly, the vibration damper may be made of one or more viscoelastic materials and may have a geometry as a flat ring. The flat ring may be concentrically positioned relative to the rotational center of the disk, and the inner diameter of the disk is larger than the diameter of the rotor on which the disk is mounted. The vibration damper may also have integrated features that allow it to attach within its assembly without dislodging, and / or may have integrated features that allow it to self-align on the encoder disk or the motor.

[0035] According to another aspect, the present invention provides a rigid structure on which a PCBA, acting as a transmitter, is mounted, and the rigid structure reduces relative movement between the transmitter and the detector, and allows light to pass from the transmitter to the detector. The rigid structure may have apertures through which light can pass, may be optimized for minimum size and compactness, may have a natural frequency higher than 2.0 kHz, may have an integrated platform supporting a vibration damper, may be made of a single sheet of metal, or may be made of components of rigid members.

[0036] Those skilled in the art will understand that many modifications and variations can be made to the embodiments disclosed above without departing from the spirit and scope of the invention.

Claims

1. An encoder system for a galvanometer, the encoder system comprising: A transmitter system comprising at least one transmitter for providing light; A detector system comprising at least one detector for detecting light; An encoder disk is connected to the rotor of the galvanometer; A rigid structure positioned between the transmitter system and the detector system, allowing light to pass through the rigid structure; and A damping system comprising at least a polymer material positioned to contact either the transmitter system or the detector system.

2. The encoder system of claim 1, wherein the transmitter system includes a transmitter printed circuit board, and the damping system includes an elastomeric material on at least one side of the printed circuit board.

3. The encoder system of claim 2, wherein the transmitter system includes a transmitter printed circuit board, and the damping system includes a first material on a first side of the transmitter printed circuit board and a second elastomeric material on a second side of the transmitter printed circuit board opposite to the first side of the printed circuit board.

4. The encoder system according to any one of claims 1 to 3, wherein the detector system includes a detector printed circuit board, and the damping system includes an elastomeric material on one side of the detector printed circuit board.

5. The encoder system according to any one of claims 1 to 4, wherein the damping system comprises an elastomeric material on the back side of the encoder disk.

6. The encoder system according to any one of claims 1 to 5, wherein the transmitter system includes a transmitter printed circuit board, and the damping system includes a first material on a first side of the transmitter printed circuit board, a second elastomeric material on a second side of the transmitter printed circuit board opposite to the first side of the printed circuit board, and a third elastomeric material on the back side of the encoder disk.

7. The encoder system of claim 6, wherein the first elastomer material, the second elastomer material and the third elastomer material each have a hardness between about 30 Shore 00 and 90 Shore 00.

8. The encoder system of claim 6, wherein the first elastomer material, the second elastomer material and the third elastomer material each have a thickness of at least about 2 mm.

9. The encoder system of claim 6, wherein at least one of the first elastomer material, the second elastomer material, and the third elastomer material is sized to fit within a recessed area of ​​a corresponding receiving surface.

10. The encoder system according to claim 1, wherein the rigid structure is integrally formed as a single unit.

11. A galvanometer system, the galvanometer system comprising: Stator assembly; The rotor within the stator assembly; as well as Encoder system, comprising: A transmitter system comprising at least one transmitter for providing light; A detector system comprising at least one detector for detecting light; An encoder disk, which is connected to the rotor of a galvanometer; and A damping system comprising at least a polymer material positioned to contact either the transmitter system or the detector system.

12. The galvanometer system of claim 11, wherein the encoder system further comprises a rigid structure positioned between the transmitter system and the detector system such that the light can pass through the rigid structure.

13. The galvanometer system according to any one of claims 11 to 12, wherein the transmitter system comprises a transmitter printed circuit board, and the damping system comprises an elastomeric material on at least one side of the printed circuit board.

14. The galvanometer system of claim 13, wherein the transmitter system includes a transmitter printed circuit board, and the damping system includes a first material on a first side of the transmitter printed circuit board and a second elastomeric material on a second side of the transmitter printed circuit board opposite to the first side of the printed circuit board.

15. The galvanometer system according to any one of claims 11 to 14, wherein the detector system includes a detector printed circuit board, and the damping system includes an elastomeric material on one side of the detector printed circuit board.

16. The galvanometer system according to any one of claims 11 to 15, wherein the damping system comprises an elastomeric material on the back side of the encoder disk.

17. The galvanometer system according to any one of claims 11 to 16, wherein the transmitter system includes a transmitter printed circuit board, and the damping system includes a first material on a first side of the transmitter printed circuit board, a second elastomeric material on a second side of the transmitter printed circuit board opposite to the first side of the printed circuit board, and a third elastomeric material on the back side of the encoder disk.

18. The galvanometer system of claim 17, wherein the first elastomer material, the second elastomer material and the third elastomer material each have a hardness between about 30 Shore 00 and 90 Shore 00.

19. The galvanometer system of claim 17, wherein the first elastomer material, the second elastomer material, and the third elastomer material each have a thickness of at least about 2 mm.

20. The galvanometer system of claim 17, wherein at least one of the first elastomer material, the second elastomer material, and the third elastomer material is sized to fit within a recessed area of ​​a corresponding receiving surface.

21. The galvanometer system according to any one of claims 11 to 20, wherein the rigid structure is integrally formed as a single unit.

22. A method of operating a galvanometer, the method comprising: This causes the rotor to rotate within the stator; The encoder disk of the encoder system rotates with the rotor, the encoder disk is connected to the rotor and housed within the encoder system, the encoder system including a transmitter system, a detector system and the encoder disk; as well as Vibrations generated within the encoder system are damped by at least a polymer material positioned to contact either the transmitter system or the detector system.

23. The method of claim 22, wherein the transmitter system includes a transmitter printed circuit board, and the damping of vibration involves providing a first material on a first side of the transmitter printed circuit board, providing a second elastomeric material on a second side of the transmitter printed circuit board opposite to the first side of the printed circuit board, and providing a third elastomeric material on the back side of the encoder disk.

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