Mitigation of electrical discharge transients in a printhead

Abstract

A method includes, at a controller of an apparatus, obtaining a delay setting corresponding to an effector head configured to interface with the apparatus, the effector head having (i) an array of effector elements, (ii) a first switch assembly controllable to deliver power to a first subset of the effector elements, and (iii) a second switch assembly configured to deliver power to a second subset of the effector elements; at the controller, activating the array of effector elements by controlling the first switch assembly to deliver power to the first subset during a first time period and controlling the second switch assembly to deliver power to the second subset during a second time period, the second time period being offset relative to the first time period according to the delay setting.

Description

Background Technology

[0001] Printheads in media handling devices such as desktop printers may include or be connected to inductive components. The operation of the printhead can cause induced discharges from these components, which can damage the printhead. Attached Figure Description

[0002] The accompanying drawings (in which the same reference numerals refer to the same or functionally similar elements in the respective individual views) are incorporated in and form part of the specification together with the following detailed description and are used to further illustrate embodiments of the concept of the claimed invention and to explain the various principles and advantages of these embodiments.

[0003] Figure 1 It's a picture of a printer.

[0004] Figure 2 yes Figure 1 A simplified cross-section of the printer, showing some of its internal components.

[0005] Figure 3 yes Figure 1 A diagram of the printer head.

[0006] Figure 4 This is a flowchart of a method to mitigate transient induced discharge.

[0007] Figure 5A It is shown Figure 4 A diagram illustrating an exemplary execution of the method in block 405.

[0008] Figure 5B It is shown Figure 4 Another exemplary implementation of the method in block 405 is shown in the diagram.

[0009] Figure 5C It is shown Figure 4 Another exemplary implementation of the method in block 405 is shown in the diagram.

[0010] Figure 6 This is a diagram showing the transient inductive discharge of the simultaneously activated printhead switching assembly.

[0011] Figure 7 It shows the basis Figure 4 The diagram shows the transient state of induced discharge in the printhead switching assembly controlled by the method.

[0012] Those skilled in the art will understand that the elements in the accompanying drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be enlarged relative to other elements to aid in understanding embodiments of the invention.

[0013] In the accompanying drawings, device and method components have been indicated by conventional symbols where appropriate, and only those specific details relevant to understanding embodiments of the invention are shown so as not to obscure this disclosure by means of details that would be obvious to those of ordinary skill in the art who would benefit from the description herein. Detailed Implementation

[0014] The examples disclosed herein relate to a method comprising: at a controller of a device, obtaining a delay setting corresponding to an actuator head configured to engage with the device, the actuator head having (i) an array of actuator elements, (ii) a first switching assembly controllable to deliver power to a first subset of the actuator elements, and (iii) a second switching assembly configured to deliver power to a second subset of the actuator elements; at the controller, activating the actuator element array by controlling the first switching assembly to deliver power to the first subset during a first time period, and controlling the second switching assembly to deliver power to the second subset during a second time period, the second time period being offset relative to the first time period according to the delay setting.

[0015] Another example disclosed herein relates to a device comprising: a power supply; an interface configured to engage with an actuator head having (i) an array of actuator elements, (ii) a first switching assembly controllable to deliver power from the power supply to a first subset of the actuator elements, and (iii) a second switching assembly configured to deliver power from the power supply to a second subset of the actuator elements; and a controller configured to: acquire a delay setting corresponding to the actuator head; and, in order to activate the array of actuator elements: control the first switching assembly to deliver power to the first subset during a first time period, and control the second switching assembly to deliver power to the second subset during a second time period, the second time period being offset relative to the first time period according to the delay setting.

[0016] Figure 1 An example device in the form of a media handling device 100, such as a label printer (also referred to herein as printer 100), is shown. As shown, printer 100 can be implemented as a desktop printer. Printer 100 can also be implemented in a variety of other shape factors, including mobile, desktop, industrial shape factors, etc. Printer 100 includes various components configured to apply markings to media, such as discrete labels, continuous paper tapes, ID cards, etc. For example, markings can be applied by direct thermal printing, thermal transfer, etc. In other examples, media handling device 100 may include a radio frequency identification (RFID) component configured to write data to RFID tags embedded in labels or other media to supplement or replace the application of markings to the media.

[0017] Printer 100 includes: a body 104 that houses a media supply source, an actuator head (such as a printhead), and other components; and a cover or door 108 configured to open (e.g., in direction 112) to provide access to the interior of printer 100. Printer 100 also includes an outlet 116 from which processed media (e.g., a marked label applied within the body 104 of printer 100) is dispensed.

[0018] Figure 2 It shows in Figure 1 The simplified cross-section of printer 100 taken at plane 120 is shown. Figure 2 As shown, body 104 and cover 108 define a chamber 200 for receiving one or more media supply sources, such as a media cartridge 204 (also referred to herein as supply source 204) containing paper rolls, label rolls, or the like 208. In other examples, the media supply source housed in chamber 200 may include a boxed fan-fold label, ID card, or the like. In still other examples, printer 100 may include an inlet in body 104 for receiving media from an external supply source, such as through chamber 200 for processing.

[0019] Media 212 from supply source 204 (e.g., from roll 208 in the illustrated example) travels along a media path from supply source 204 to the impression zone formed by printhead 216 and pressure roller 220. The media path may be defined by surfaces, rollers, etc., such as guide roller 218 (e.g., a passive or non-driven roller). Pressure roller 220 may be driven, for example, to pull media 212 along the media path and through the impression zone, where printhead 216 applies a mark to media 212. The processed media (e.g., carrying the mark applied by printhead 216) is then distributed at exit 116.

[0020] The markings applied to the medium 212 by the printhead 216 can be provided to the printhead 216 by a controller 228 contained within the body 104 of the printer 100. The controller 228 can be implemented, for example, as a field-programmable gate array (FPGA) implementing firmware logic, or as another suitable controller, such as a processor or other logic circuit, that executes stored computer-readable instructions to implement firmware logic. Such instructions, and / or configuration data used during the execution of such instructions, can be stored in the controller 228 and / or in a non-transitory computer-readable medium, such as a memory 232 connected to the controller 228.

[0021] For example, controller 228 can receive print data, such as text or images, to be applied to medium 212 from a host computing device (e.g., a desktop computer, smartphone, server, etc.) via a communication interface connected to controller 228 and supported within body 104. Controller 228 can be configured to control printhead 216 to apply markings corresponding to the print data to medium 212 in response to receiving print data (e.g., in the form of print instructions from the aforementioned host computing device).

[0022] Printhead 216 includes an array of actuator elements, such as discrete thermal elements (e.g., resistive elements), also referred to as dots. For example, the array could be a linear array (e.g., a row of dots, one dot wide) extending across the media path along which media 212 travels. The actuator elements can be individually activated to apply heat to corresponding portions of media 212. As will be understood, for direct thermal printers, such as… Figure 2 As shown, applying heat to a portion of the medium 212 can activate the thermochromic pigment in the medium 212. In a thermal transfer printer, the ribbon can pass through the printing zone with the medium 212, and applying heat to a portion of the medium 212 and the ribbon can cause the pigment to transfer from the ribbon to the medium 212.

[0023] To control the printhead 216 in applying markings to the media 212, the controller 228 can transmit a sequence of instructions to the printhead 216, each instruction defining the activation state of a row at each point on the printhead 216. The activation state can be a binary state indicating whether each point is to be activated (e.g., powered on to generate heat that can be used to print onto the corresponding area of ​​the media 212, so that the corresponding area has ink) or remain inactive (e.g., powered off so that no heat is generated and the corresponding area of ​​the media 212 remains uncolored).

[0024] As discussed in more detail below, in response to transmitting an instruction to printhead 216 defining a line activation state, controller 228 can be configured to provide power to the actuator elements of printhead 216, for example, from power supply 236 of printer 100. Power supply 236 may include suitable circuitry for providing power to components of printer 100 from a source such as a battery, external power outlet, etc. In some examples, power supply 236 may include power conduit 240, such as a cable, for connection to printhead 216.

[0025] refer to Figure 3A schematic diagram of an example printhead 216 that can be mounted in printer 100 is shown. A controller 228, a power supply 236, and a conduit 240 are also shown, along with an interface 300 of printer 100 configured to connect the controller 228 to the printhead 216. Interface 300 may include a physical connector, for example, a physical connector having multiple pins or other structures configured to engage with a corresponding structure of the printhead 216. In some examples, the conduit 240 may also be connected to the printhead 216 via interface 300.

[0026] Figure 3 The dashed lines indicate connections used for exchanging control data, while the solid lines indicate connections used for power delivery. In other examples, control data and power delivery may be carried over the same physical connection. Figure 3 The simplified layout shown is for illustrative purposes only.

[0027] Printhead 216 includes an array of actuator elements 304. While in the illustrated example, printhead 216 includes sixteen elements, other printheads may include arrays with a variety of different dot counts. For example, a printer configured to process four-inch wide labels may accept a printhead with an array of approximately eight hundred dots (e.g., approximately two hundred dots per inch for the resolution on the label). The number of dots in array 304 can be selected based on the size of the media (e.g., width), the desired print quality (e.g., for a given media size, a larger number of dots typically corresponds to higher print quality), printhead cost (e.g., for a given media size, a smaller number of dots typically corresponds to lower printhead cost), and so on.

[0028] Printhead 216 includes a data port configured to receive instructions from controller 228 defining the activation state of each actuator (e.g., dot) in array 304. Each instruction may include, for example, a string of bits defining whether each actuator element in array 304 is activated. For example, a value "1" in the instruction activates the corresponding dot to apply heat to medium 212, while a value "0" keeps the corresponding dot inactive (no heat applied).

[0029] Instructions received from controller 228 can be stored in a buffer or other memory 308. In this example, memory 308 is implemented as a shift register 308a and a latch register 308b. Shift register 308a can be configured to receive data serially from controller 228 and can provide one bit of storage for each point in array 304. Shift register 308a can controllably transfer data (e.g., the active state of a row in array 304) to latch register 308b, which can also include one bit of storage for each point in array 304. The stored value in latch register 308b can define the active state of a point in array 304. However, various other implementations of memory 308 are also possible. For example, instructions received from controller 228 can each include sixteen bits corresponding to a point in array 304. The bits of a given instruction are stored in memory 308 at the location corresponding to the corresponding point in array 304.

[0030] To activate the elements of array 304 according to instructions stored in memory 308, printhead 216 includes controllable switching components to supply power from power supply 236 to the points that are active in memory 308. In the illustrated example, printhead 216 includes a first switching component 312-1 configured to deliver power to a first subset of the actuator elements, specifically to seven of the sixteen points of array 304. Printhead 216 also includes a second switching component 312-2 configured to deliver power to a second subset of the actuator elements, specifically to the remaining nine points of array 304. The subset of points to which each switching component 312 can deliver power is mutually exclusive (i.e., no point is powered by both switching components 312), and each subset represents approximately half the size of array 304 (but not necessarily exactly half). In other examples, printhead 216 may include more than two switching components 312. The corresponding portions of the elements of array 304 activated by each switching component 312 are approximately equal. For example, in the illustrated embodiment, each switching component 312 can supply power to approximately half of the array 304. In the example with three switching components, each switching component supplies power to approximately one-third of the array 304. The approximately equal portions of the actuator elements supplied with power by each switching component, relative to unequal portions, allow for more effective mitigation of induced discharges caused by the activation of each switching component.

[0031] Despite Figure 3In this diagram, the switching component 312 is shown as a different hardware element from the memory 308, but the switching component 312 and the memory 308 can be implemented via shared hardware elements, such as one or more integrated circuits (ICs) implementing the memory 308 connected to or integrated with one or more semiconductor devices implementing the switching component 312 (e.g., one or more metal-oxide-semiconductor field-effect transistors, or MOSFETs). Furthermore, although the switching component 312 is shown as being disposed between a point and ground, the switching component 312 can be disposed between the power supply 236 and their respective points in the array 304.

[0032] In addition to providing instruction data to the printhead 216 for storage in the memory 308, the controller 228 also sends control signals, also known as strobe signals, to each switch assembly 312. For example, to apply a row of markers to the medium 212, the controller 228 may send instruction data to the memory 308 and then activate switch assemblies 312-1 and 312-2 to allow current to flow from the power conduit 240 through the array 304 according to the activation state defined in the memory 308. When the switch assembly 312 has been activated for a predetermined period of time, sufficient to heat the points of the array 304 that are in an active state in the memory 308, thereby applying heat to the medium 212, the controller 228 may deactivate switch assemblies 312-1 and 312-2 and clear the memory 308 for the next row of instruction data. The above process (loading instruction data to set the activation state, triggering strobes to heat the corresponding elements, disabling strobes, and clearing instruction data) can be repeated as needed to apply a continuous row of markers to the medium 212 as it passes through the printhead 216.

[0033] Certain components of printer 100 and / or printhead 216 (e.g., power conduit 240) may function as inductors during printer 100 operation. It will be apparent to those skilled in the art that the degree of inductance exhibited by power conduit 240 and / or other cables in device 100 may depend on cable length, stranding configuration, number of wires within the cable, etc. For example, power conduit 240 may have an inductance between approximately 100 nH and 500 nH (but various other power conduit inductors may also be applicable depending on the construction of printhead 216 and printer 100). Therefore, enabling switching components 312-1 and 312-2 may result in magnetic energy being stored in power conduit 240, while disabling switching components 312-1 and 312-2 may result in the stored energy being discharged from conduit 240 into printhead 216. This inductive discharge can cause transient voltages applied to array 304 and / or switching assembly 312 (voltages that could be sufficient to damage these components), and can also cause current surges at various components of printhead 216, creating thermal stress on these components (e.g., dots and switching assembly 312 in array 304).

[0034] For example, in printhead 216 powered at 24V from conduit 240, voltage transients caused by induced discharge may exceed + / - 10V. During gating triggering, the current supplying the array 304 with the instruction data to set most of the array 304 to an active state (e.g., all points of array 304 are activated to apply a colored line extending completely across medium 212) may be approximately 45A, and current surges caused by induced discharge may exceed an additional 40A. It will be apparent to those skilled in the art that the above values ​​are provided for illustrative purposes only, and a wide variety of voltage transients and current surges can be observed for various printhead configurations. The aforementioned voltage transients and / or current surges may shorten the lifespan of printhead 216 and / or cause malfunctions.

[0035] To mitigate the potential effects of induced discharge from conduit 240, printhead 216 may include one or more capacitors 316 configured to store energy generated by induced discharge. However, providing sufficient capacitance to mitigate damage to array 304 and / or switching assembly 312 may increase the cost and complexity of printhead 216.

[0036] Therefore, controller 228 implements certain additional functions to mitigate transients caused by induced discharge. As discussed in more detail below, controller 228 is configured to enable and disable switching components 312-1 and 312-2 at different times (rather than simultaneously). The delay between enabling and disabling switching components 312-1 and 312-2 is selected to mitigate transients caused by induced discharge via destructive interference of the transient signals. In devices implementing the functions discussed below, the capacitance provided at printhead 216 for absorbing induced discharge can be reduced. For example, the size of capacitor 316 can be reduced compared to devices that do not implement the mitigation functions discussed herein.

[0037] refer to Figure 4 This illustrates a method 400 for mitigating transients caused by induced discharge. The method 400 is described below in conjunction with exemplary execution of the controller 228. It should be understood that the method 400 can also be executed in various other printers 100 and other devices having actuator components (e.g., other arrays of thermal elements).

[0038] In block 405, controller 228 is configured to acquire a delay setting corresponding to printhead 216 or other suitable actuator head. The delay setting defines a time period that the controller uses to separate the activation of switch assembly 312-1 from the activation of switch assembly 312-2. The length of the time period defined by the delay setting is selected to produce destructive interference between transients generated by induced discharge from power conduit 240 in response to the disabling of each switch assembly 312. That is, the delay setting shifts the time period during which switch assembly 312-1 delivers power relative to the time period during which switch assembly 312-2 delivers power, such that the transients generated by induced discharge when switch assembly 312-1 is disabled are destructive to the transients generated by induced discharge associated with the disabling of switch assembly 312-2.

[0039] The transient generated by induced discharge can have a resonant frequency, which is generated by the magnetic field collapse at power conduit 240 driving current to capacitor 316. Therefore, the voltage at capacitor 316 may rise above the power supply voltage on the power bus connecting conduit 240 and capacitor 316. Thus, capacitor 316 can drive current back into conduit 240. This cycle can repeat at the resonant frequency until capacitor 316 and / or other components in printhead 216 have dissipated the energy generated by the induced discharge. The resonant frequency can be approximated by modeling printhead 216 and conduit 240 as a resonant circuit (LC circuit). Therefore, the transient frequency when a single switching component 312 is disabled (or when both switching components are disabled simultaneously) can be approximated by Equation 1 below. Equation 1

[0040] In Equation 1, f0 is the resonant frequency, L is the inductance of the power conduit 240, and C is the estimated total capacitance of the printhead 216 (e.g., the capacitance of capacitor 316, and the estimated capacitance of other components with parasitic capacitance, such as the MOSFETs connected to the integrated circuit implementing the memory 308 and the switching components 312). For example, the resonant frequency of a power conduit with a 300 nH inductor and a 1.4 μF capacitor is approximately 245 kHz. To obtain destructive interference between transients associated with each switching component 312 being disabled, the transients associated with each switching component 312 can be offset relative to each other by approximately half the reciprocal of the aforementioned frequency, or approximately 2 μs (or 180 degrees).

[0041] The delay setting can be obtained in box 405 through various mechanisms. For example, go to Figure 5AThe printhead 216 can store the delay setting 500 in memory, such as an electrically erasable programmable read-only memory (EEPROM) or other suitable non-volatile memory. Therefore, for example, when the printer 100 is powered on, the controller 228 can retrieve the delay setting 500 from the printhead 216.

[0042] In other examples, such as Figure 5B As shown, printhead 216 may (e.g., in the memory described above) store printhead identifier 504, such as model number, etc. Controller 228 may be configured to retrieve identifier 504 when printer 100 is powered on and look up configuration data from repository 508 in memory 232. Repository 508 may include configuration data including delay settings for each of a plurality of printheads compatible with printer 100.

[0043] In other examples, such as Figure 5C As shown, controller 228 can be configured to dynamically determine the delay setting. For example, controller 228 can be configured to, for instance, test any one or both of the trigger switch assemblies 312 simultaneously when printer 100 is powered on, and measure the frequency of the "ringing" current generated by the induced discharge to printhead 216 when switch assembly 312 is disabled. For example, printhead 216 may include a shunt resistor for sensing the resonant frequency. In other examples, printhead 216 may include a Hall effect sensor to measure the resonant frequency of the ringing current. In other examples, controller 228 can be configured to measure the resonant frequency via interface 300, for example, interface 300 may include connections to implement a Kelvin 4-wire measurement circuit. Controller 228 can then determine half a cycle of the sensed resonant frequency of the induced discharge transient and determine delay setting 512 based on the resonant frequency as described above. The determined delay setting 512 can be stored in memory 232, for example, until printer 100 is powered off.

[0044] return Figure 4 In block 410, controller 228 is configured to load instruction data into memory 308 of printhead 216. For example, controller 228 may receive print data (e.g., images, text, etc.) from a host computing device as described above, and may convert the print data into a line of instruction data for supplying to printhead 216. Therefore, in block 410, controller 228 is configured to supply the next line of instruction data to printhead 216, for example, by writing that line of instruction data into memory 308.

[0045] In block 415, controller 228 is configured to activate the first switch assembly 312-1. The second switch assembly 312-2 is not activated simultaneously with the first switch assembly 312-1. Instead, controller 228 is configured to activate the second switch assembly 312-2 in block 420, such that the time at which switch assemblies 312 are activated (to deliver power to the corresponding elements of array 304) is offset by a delay setting relative to each other. The execution of block 420 is separated from the execution of block 415 by a time period 422 defined by the delay setting. For example, time period 422 can be between approximately 1 μs and approximately 10 μs. It will be apparent to those skilled in the art that time period 422 can vary for different printers.

[0046] After execution block 420, both switching components 312 are activated, thus powering array 304 and heating the points with active states according to memory 308. At block 425, controller 228 is also configured to deactivate switching component 312-1 after a predetermined time period 426 has elapsed since execution block 415. Time period 426 can vary depending on the printhead. For example, time period 426 can be between approximately 100 μs and approximately 500 μs (but shorter or longer activation time periods can also be used). In other words, delay period 422 can be shorter than approximately 10% of time period 426, and in some examples, shorter than approximately 1% of time period 426.

[0047] In block 430, controller 228 is configured to deactivate switch components 312-2 after a predetermined time period 426 has elapsed since execution block 420. Therefore, the time periods for which switch components 312 are activated are equal, but offset relative to each other by a delay time period 422.

[0048] In box 435, controller 228 is configured to determine whether the current print job is complete. When the determination at box 435 is negative, controller 228 returns to box 410. When the determination at box 435 is positive, execution of method 400 ends.

[0049] Although in the example above, switch component 312-1 is activated and deactivated earlier than switch component 312-2, in other implementations, switch component 312-2 may be activated and deactivated earlier than switch component 312-1. The time periods 426 during which switch component 312 actively provides power to array 304 overlap, but are not simultaneous (e.g., switch components 312 are not activated or deactivated within a time interval of less than 0.1 μs, which can be considered simultaneous depending on the clock frequency of controller 228).

[0050] Figure 6An example transient signal 600 generated by induced discharge is shown when the switching component 312 is simultaneously triggered (e.g., activated and deactivated). Figure 6 As shown, the voltage surge at power conduit 240 relative to the nominal 24V can exceed 10V. Similarly, as... Figure 6 As shown, time period 422 corresponds to half a cycle (or 180 degrees) of transient signal 600. Figure 7 An example transient signal 700 generated by induced discharge is shown when the switching assembly 312 is triggered within a time period offset from each other by time period 422. Figure 7 As shown, the destructive interference between transients caused by the deactivation of each switch assembly 312 may lead to a decrease in the total transient signal, reducing the energy dissipated by the capacitor 316 and / or reducing the thermal stress on the switch assembly 312, the connectors in the printhead 216, etc.

[0051] In other embodiments, mitigation of transients caused by induced discharge can be achieved in printhead 216 with a single strobe signal. This single strobe signal can control, for example, a switching component 312. Alternatively, printhead 216 can have a single switching component 312 for each point in the array, and a single strobe signal can control a single switching component 312. For example, controller 228 can be configured to preprocess each line of data given to printhead 216 into two or more distinct lines. Each line of data can be input to shift register 308a and then to latch register 308b to set the activation state of each point. Clearly, latch register 308b can store a line of data while shift register 308a receives the next line of data.

[0052] For example, the first of two rows generated by controller 228 may include the bits to be input to the first half of shift register 308a, while the remaining half of the bits in the first row may be set to zero (invalid). The second row may include the bits to be input to the second half of shift register 308a, and the first half has no value. Controller 228 can then be configured to apply the first row to shift register 308a and then to latch register 308b before activating the strobe signal. Thus, half of the points in array 304 are activated according to the state set in the original data row. Controller 228 can then apply the second row to shift register 308a. The second row does not include a value for the first half of the original data and therefore does not overwrite the value of the first half in latch register 308b when applied. Controller 228 can be configured to transfer the value of the second row to latch register 308b after the aforementioned delay period has elapsed, while continuing to apply the strobe signal. Therefore, once the delay period has elapsed, the complete row of the original data is applied via array 304. The delay between the activation of the first and second halves of array 304 can produce destructive interference between the previously described induced discharge transients. Controller 228 can also be configured to reset the first half of latch register 308b, deactivate half of array 304, and reset the second half of latch register 308b after the delay period has elapsed. In other words, the functionality of two or more switching components 312 can be achieved through a combination of switching components 312 with time-division control of shift register 308a and latch register 308b.

[0053] Specific embodiments have been described in the foregoing specification. However, those skilled in the art will understand that various modifications and changes can be made without departing from the scope of the invention as set forth in the following claims. Therefore, the specification and drawings are to be considered illustrative rather than restrictive, and all such modifications are intended to be included within the scope of the invention.

[0054] Benefits, advantages, solutions to problems, and any elements that may lead to or make any benefit, advantage, or solution occurring or more apparent shall not be construed as key, essential, or fundamental features or elements of any or all claims. The invention is defined solely by the appended claims, which include any modifications made during the pending period of this application and all equivalents of those published claims.

[0055] Furthermore, in this document, relational terms such as first and second, top and bottom may be used only to distinguish one entity or action from another, without necessarily requiring or implying any actual such relationship or order between these entities or actions. The terms “comprises,” “comprising,” “has,” “having,” “includes,” “including,” “contains,” “containing,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes, has, contains, or contains a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to such a process, method, article, or apparatus. Without further limitation, an element beginning with “comprises,” “has,” “includes,” or “contains” does not exclude the presence of additional identical elements in a process, method, article, or apparatus that includes, has, contains, or contains that element. The terms “a” and “an” are defined as one or more unless expressly stated otherwise herein. The terms “substantially,” “essentially,” “approximately,” “about,” or any other form thereof are defined to be close to the meaning understood by one of ordinary skill in the art, and in one non-limiting embodiment, the term is defined as within 10%, in another within 5%, in yet another within 1%, and in still another within 0.5%. The term “connection” as used herein is defined as a link, but not necessarily a direct link, and not necessarily a mechanical link. A device or structure “constructed” in a certain way is constructed at least in that manner, but may also be constructed in ways not listed.

[0056] Certain expressions may be used in this document to list combinations of elements. Examples of such expressions include: “at least one of A, B, and C”; “one or more of A, B, and C”; “at least one of A, B, or C”; “one or more of A, B, or C”. Unless otherwise expressly stated, the above expressions cover any combination of A and / or B and / or C.

[0057] It should be understood that some embodiments may consist of one or more dedicated processors (or "processing devices") and unique stored-program instructions (including software and firmware), such as microprocessors, digital signal processors, custom processors, and field-programmable gate arrays (FPGAs), which control the one or more processors to implement some, most, or all of the functions of the methods and / or devices described herein, together with some non-processor circuitry. Alternatively, some or all of the functions may be implemented by a state machine without stored-program instructions, or in one or more application-specific integrated circuits (ASICs), wherein each function or some combination of functions is implemented as custom logic. Of course, a combination of these two approaches may also be used.

[0058] Furthermore, embodiments can be implemented as computer-readable storage media on which computer-readable code is stored for programming a computer (e.g., including a processor) to perform the methods described and claimed herein. Examples of such computer-readable storage media include, but are not limited to, hard disks, CD-ROMs, optical storage devices, magnetic storage devices, ROMs (read-only memories), PROMs (programmable read-only memories), EPROMs (erasable programmable read-only memories), EEPROMs (electrically erasable programmable read-only memories), and flash memory. Moreover, it is conceivable that, although considerable effort may be required, for example, due to available time, current technology, and economic considerations, and many alternative designs exist, such software instructions, programs, and integrated circuits can be readily created by those skilled in the art with minimal experimentation, guided by the concepts and principles disclosed herein.

[0059] An abstract of this disclosure is provided to allow readers to quickly identify the core of the technical disclosure. The submitted abstract should not be construed as limiting the scope or meaning of the claims. Furthermore, as can be seen from the foregoing detailed description, various features have been combined in various embodiments for the purpose of simplifying the invention. The method of the invention should not be construed as reflecting an intention to require more features than expressly recited in each claim. Rather, as reflected in the following claims, the inventive subject matter may be embodied in fewer than all the features of a single disclosed embodiment. Therefore, the following claims are hereby incorporated into the detailed description, wherein each claim independently constitutes a separately claimed subject matter.

Claims

1. A method comprising: At the device controller, a delay setting corresponding to an actuator head configured to engage with the device is obtained, the actuator head having: (i) an array of actuator elements; and (ii) a first switching assembly capable of being controlled to deliver power to a first subset of the actuator elements. and (iii) a second switching assembly configured to deliver power to a second subset of the actuator elements; The actuator element array is activated at the controller in the following manner: Control the first switching component to deliver power to the first subset during a first time period, and The second switching component is controlled to deliver power to the second subset during a second time period, which is offset relative to the first time period according to the delay setting.

2. The method according to claim 1, wherein, The first time period and the second time period have the same length.

3. The method according to claim 1, wherein, The delay setting is limited to an offset of less than 10% of the lengths of the first time period and the second time period.

4. The method according to claim 1, wherein, Obtaining the delay setting includes: Receive the identifier of the actuator head; and The delay setting is retrieved from memory based on the identifier.

5. The method according to claim 1, wherein, Obtaining the delay setting includes: The delay setting is retrieved from the memory of the actuator head via an interface.

6. The method according to claim 1, wherein, Obtaining the delay setting includes: Control the first switching assembly and the second switching assembly to simultaneously deliver power to the first subset and the second subset of the actuator elements; Measuring the frequency of induced discharge associated with the power source; and The delay setting is determined based on the frequency.

7. The method according to claim 6, wherein, The delay setting is half the reciprocal of the frequency.

8. An apparatus comprising: power supply; An interface configured to engage with an actuator head having: (i) an array of actuator elements; (ii) A first switching assembly, the first switching assembly being controllable to deliver power from the power source to a first subset of the actuator elements; and (iii) a second switching assembly configured to deliver power from the power source to a second subset of the actuator elements; as well as The controller is configured to: Obtain the delay setting corresponding to the actuator head; and To activate the actuator element array: Control the first switching component to deliver power to the first subset during a first time period, and The second switching component is controlled to deliver power to the second subset during a second time period, which is offset relative to the first time period according to the delay setting.

9. The device according to claim 8, wherein, The first time period and the second time period have the same length.

10. The device according to claim 8, wherein, The delay setting is limited to an offset of less than 10% of the lengths of the first time period and the second time period.

11. The device according to claim 8, wherein, The controller is configured to obtain the delay setting in the following manner: Receive the identifier of the actuator head; and The delay setting is retrieved from memory based on the identifier.

12. The device according to claim 8, wherein, The controller is configured to obtain the delay setting in the following manner: The delay setting is retrieved from the memory of the actuator head via the interface.

13. The device according to claim 8, wherein, The controller is configured to obtain the delay setting in the following manner: Control the first switching assembly and the second switching assembly to simultaneously deliver power to the first subset and the second subset of the actuator elements; Measure the frequency of the induced discharge associated with the power source; as well as The delay setting is determined based on the frequency.

14. The device according to claim 13, wherein, The delay setting is half the reciprocal of the frequency.

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