Power tool wake-up

Abstract

A power tool includes a housing, a trigger, a motor coupled to an output member, and a motor drive circuit coupled to the motor. The power tool further includes a motor controller coupled to the motor drive circuit. The motor control circuit is configured to detect an input received from the sensor indicating that a wake-up operation is required. The motor control circuit is further configured to determine whether the power tool is in a sleep state and initiate a wake-up operation in response to receiving the input and determining that the power tool is in the sleep state.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 314,732, filed February 28, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments described herein relate to waking a powered tool from a sleep or standby state based on detected motion of the powered tool. Utility Model Content

[0004] Battery-powered vehicles can enter sleep or standby mode when not in use for a period of time in an effort to extend battery life. Normally, the vehicle is awakened or exits sleep / standby mode when the user takes a positive action (such as pressing a trigger). However, the time required to exit sleep / standby can cause a delay between the user pressing the trigger and the motor starting to operate.

[0005] The embodiments described herein provide a reduction in the "downtime" from trigger activation to activation of the power tool.

[0006] The power tool described herein includes a housing, a trigger, a sensor, a motor coupled to an output component, a motor drive circuit coupled to the motor, and a motor controller coupled to the motor drive circuit. The motor controller is configured to detect an input received from the sensor indicating a need for a wake-up operation. The motor controller is also configured to determine whether the power tool is in a sleep state and, in response to detecting the input and determining that the power tool is in a sleep state, initiate a wake-up operation.

[0007] On one hand, the motor controller is further configured to start a timer when the wake-up operation is initiated, determine whether an interrupt signal is received at the motor controller, and determine that the timer has expired. The motor controller is also configured to resume operation in sleep mode in response to the timer expiring and no interrupt signal being received.

[0008] On the other hand, the interrupt signal is actuated by a trigger.

[0009] On the other hand, the sensor is selected from at least one of the following: accelerometer, piezoelectric sensor, and capacitive wake-up sensor.

[0010] On the other hand, the wake-up operation prepares the motor to operate immediately upon receiving input from the trigger.

[0011] On the other hand, the sensor is configured to detect the pressure of the user gripping the power tool.

[0012] In another aspect, the sensor is an ultrasonic sensor configured to detect a user's hand on the power tool.

[0013] The processes described herein include a method for initiating a wake-up operation in a power tool. The method includes detecting an input received from a sensor of the power tool indicating that a wake-up operation is needed. The method also includes determining whether the power tool is in a sleep state and initiating the wake-up operation in response to detecting the input and determining that the power tool is in the sleep state.

[0014] In an aspect, the interrupt signal is generated by a user input received at a user interface of the power tool.

[0015] In another aspect, the wake-up operation initializes a motor of the power tool to operate immediately upon receiving an input from a trigger.

[0016] In another aspect, the sensor is at least one selected from the group consisting of a capacitive sensor, a piezoelectric sensor, and an accelerometer.

[0017] In another aspect, the sensor is a pressure sensor configured to detect a user's grip on the power tool.

[0018] In another aspect, the sensor is an ultrasonic sensor configured to detect a user's hand on the power tool.

[0019] The power tools described herein include a housing, a user interface, a sensor, a motor coupled to an output member, a motor drive circuit connected to the motor and configured to drive the motor in response to a drive signal received from the user interface, and a motor controller connected to the motor drive circuit, the motor controller configured to receive an input from the sensor, determine whether the input received from the sensor exceeds a predetermined value, determine whether the power tool is in a sleep state, and initiate a wake-up operation in response to determining that the input received from the sensor exceeds the predetermined value and that the power tool is in the sleep state.

[0020] In an aspect, the motor controller is further configured to start a timer upon initiating the wake-up operation, determine whether an interrupt signal is received, determine that the timer has expired, and resume the sleep state in response to the timer expiring and no interrupt signal being received.

[0021] In another aspect, the interrupt is a user input received from the user interface.

[0022] In another aspect, the sensor is a piezoelectric sensor.

[0023] In another aspect, the sensor is a capacitive sensor.

[0024] In another aspect, the sensor is a mechanical accelerometer.

[0025] Before any embodiments are explained in detail, it is to be understood that the embodiments are 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 accompanying drawings. The embodiments are capable of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled," and variations thereof, are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings.

[0026] In addition, it should be appreciated that embodiments can include hardware, software, and electronic components or modules that, for purposes of discussion, can be illustrated and described as if the majority of the components were implemented solely in hardware. However, those skilled in the art will appreciate that the embodiments described herein are merely examples and not necessarily the only way in which such methods can be implemented. In fact, one of ordinary skill in the art can appreciate that some of the acts rendered by the electronic-based aspects can be implemented in software in response to being executed by one or more processing unit(s) such as a microprocessor and / or application specific integrated circuits ("ASIC"). As such, it should be noted that embodiments can be implemented with a multitude of hardware and software configurations, to achieve the stated functionality, and that the choice of the hardware and software can depend on the particular application and on only a single software-based or hardware-based implementation can be utilized. Additionally, the disclosure can be implemented as a UEFI firmware, BIOS, or other type of firmware.

[0027] Relative terms, such as "about," "approximately," "substantially" and variations thereof, when used in connection with a quantity or condition, are understood to encompass the absolute value and to have the meaning dictated by the context (e.g., the term encompasses at least a degree of error associated with the measurement accuracy, tolerances [e.g., of manufacturing, assembly, use, etc.] associated with a particular value, etc.). Such terms are also to be construed to disclose a range defined by the absolute values of two endpoints. For example, the expression "from about 2 to about 4" also discloses the range "from 2 to 4." Relative terms can refer to a positive or negative percentage (e.g., 1%, 5%, 10%, or more) of the indicated value.

[0028] It should be appreciated that while certain diagrams are shown depicting hardware and software within a particular device, these depictions are for illustration only. Functions described herein as being performed by one component can be performed by multiple components in a distributed manner. Likewise, functions performed by multiple components can be consolidated and performed by a single component. In some embodiments, the depicted components can be combined or divided into separate software, firmware, and / or hardware. For example, logic and processing can be distributed among more than one electronic processor, rather than being located within a single electronic processor. Whether hardware components and software components are combined or divided, these hardware and software components can be located on the same computing device or can be distributed among different computing devices connected through one or more networks or other suitable communication links. Similarly, a component described as performing particular functionality can also perform additional functionality that is not described herein. For example, a device or structure "configured" in a certain way is configured in at least that way but can also be configured in ways that are not explicitly listed.

[0029] Other aspects of these embodiments will become apparent by consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a perspective view of a power tool including a trigger in accordance with some embodiments.

[0031] Figure 2 is a block diagram of a power tool control system in accordance with some embodiments.

[0032] Figure 3 is a circuit diagram of a power switch network in accordance with some embodiments.

[0033] Figures 4A-4B is a circuit diagram illustrating a piezoelectric wake-up sensor in accordance with some embodiments.

[0034] Figures 5A-5B is a circuit diagram illustrating a capacitive wake-up sensor in accordance with some embodiments.

[0035] Figures 6A-6B is a circuit diagram illustrating a mechanical wake-up sensor in accordance with some embodiments.

[0036] Figure 7 is a flowchart illustrating a process for initiating a wake-up operation in accordance with some embodiments. DETAILED DESCRIPTION

[0037] Figure 1An example power tool 100 according to some embodiments is shown. The power tool 100 includes a housing 105, a battery pack interface 110, a driver 115 (e.g., a chuck or bit holder), and an input such as a trigger assembly 120. The power tool 100 can further have a forward-reverse selector 122 that can allow a user to control the direction of a rotating portion of the tool. The power tool 100 can also have a mode selector input or other user interface element such as a clutch ring, gear selector, speed selector, etc. In other embodiments, the power tool 100 can further include various sensors 124 such as motion sensors (e.g., gyroscopes and / or accelerometers) to provide information related to the orientation (e.g., up, level, down, etc.) or movement of the power tool 100 to a controller of the power tool 100 (described below). The controller can use the movement information to determine that the tool is in motion and initiate a wake-up operation as described in more detail below.

[0038] While Figure 1 A particular power tool with a rotary output is shown, but it is contemplated that the wake-up operations described herein can be used for a variety of types of power tools such as drills, drivers, impact drivers, impulse drivers, saws (e.g., band saws, circular saws, miter saws, etc.), lights, hammer drills, nail guns, nail guns, liquid dispensers (e.g., caulk guns), crimping and / or clamping devices, and / or another type of power tool that uses a brushless DC motor controlled via a user input (e.g., a trigger).

[0039] Figure 2 Is Figure 1 A block diagram of an example power tool 100. The power tool 100 includes a power source 202, a motor drive circuit 204 (such as a field effect transistor (FET)), a motor 206, an output unit 208 (e.g., the driver 115), a Hall effect sensor 210, a motor controller 212, a trigger 214 (such as the trigger assembly 120), one or more accelerometers 216, one or more wake-up sensors 218, and a user interface 220. While described herein as a trigger 214, other input types (such as a button, a slider, a pressure sensor, etc.) are also contemplated as suitable for a given application. The Hall effect sensor 210 provides motor information feedback to the motor controller 212 such as motor rotational position information that the motor controller 212 can use to determine the position, speed, and / or acceleration of the motor 206. In some embodiments, other sensing techniques such as back-EMF sensing can allow determination of motor speed without the need for a Hall effect sensor 210.

[0040] One or more accelerometers 216 are configured to detect motion of the tool 100 and provide data to the controller 212 indicative of the tool 100 being in motion. In some examples, the accelerometers 216 can generate an output to the controller 212 when the detected motion exceeds a predetermined value, thereby indicating that the tool 100 is in motion. In other embodiments, data is provided by the accelerometers 216 to the controller 212 when any motion is detected. The controller 212 can then determine that the tool 100 is in motion and that the wake-up operation is required. One or more wake-up sensors 218 are configured to provide other indications to the motor controller 212 that the tool 100 is being manipulated by a user (e.g., gripped, carried, etc.). Various sensors, such as photoelectric sensors, pressure sensors, etc., can be used as the wake-up sensors 218, as will be described in greater detail below.

[0041] The motor controller 212 includes an electronic processor and a memory storing instructions that, when executed by the electronic processor, cause the motor controller 212 to perform the functions of the controller described herein. For example, the memory of the motor controller 212 can include a wake-up application 222 that can include instructions configured to perform the various wake-up functions described herein. The motor controller 212 is configured to receive input from the wake-up sensors 218 indicative that the power tool 100 should wake-up. The motor controller 212 is also configured to receive input from the user interface 220, such as a trigger mapping profile, etc.

[0042] The user interface 220 can be configured to receive input from or provide feedback to one or more users. For example, the user interface 220 can be a display configured to provide information to a user regarding the status or mode of operation of the power tool 100. For example, the user interface 220 can be a series of LEDs or other indicators, a touch screen, a display screen, or other visual device.

[0043] In some embodiments, the motor 206 is electronically controlled, rather than controlled using a gear box or mechanical controls. In response to motor information feedback from the Hall effect sensor 210 and user control input from the trigger 214, the motor controller 212 transmits control signals to accurately control the motor drive circuit 204 to drive the motor 206. By selectively enabling and disabling the motor drive circuit 204, power received from the power source 202 is selectively applied to the motor 206 to cause the rotor of the motor 206 to rotate. The rotating rotor of the motor 206 drives the output unit 208. In some embodiments, the motor speed indicated by the output of the Hall effect sensor 210 enables the motor controller 212 to implement closed loop speed control. As the load on the motor 206 varies during operation, the closed loop speed control enables the motor controller 212 to adjust the motor power to maintain the RPM selected by the trigger 214. For example, using closed loop speed control, the motor controller 212 can increase the motor power to maintain the selected maximum RPM as the load increases. The control signals sent by the motor controller 212 to the motor drive circuit 204 can include pulse width modulation (PWM) signals that drive the speed of the motor 206 based on the duty cycle of the PWM signals.

[0044] The motor controller 212 and other components of the power tool 100 are electrically coupled to and receive power from the power source 202. In some embodiments, the power source 202 includes one or more lithium ion battery packs. In one example, the power source 202 includes an 18 V lithium ion battery pack. However, lithium ion battery packs greater than 18 V or less than 18 V are also contemplated. In other embodiments, the power source 202 can be other energy storage devices, such as alkaline batteries, lead acid batteries, nickel metal hydride batteries, etc. In still further embodiments, the power source 202 can be an AC power source, such as provided by a utility.

[0045] Figure 3A circuit diagram of the motor drive circuit 300 is illustrated. The motor drive circuit 300 is described with respect to the power tool 100 and includes the power source 202, the motor drive circuit 204, and the motor 206. The power source 202 is coupled to the power tool 100 via the power source connection 302. In one embodiment, the power source connection 302 is the battery pack interface 110 described above. The motor drive circuit 204 includes a plurality of high-side power switching elements 304 (e.g., field effect transistors [FETs]) and a plurality of low-side power switching elements 306 (e.g., FETs), for example. The motor controller 212 provides control signals to control the high-side power switching elements 304 and the low-side power switching elements 306 to drive the motor 206 based on the motor feedback information and the user controls as described above. For example, in response to detecting a pull of the trigger 214, the motor controller 212 provides control signals to selectively (e.g., sequentially, in pairs) enable and disable the power switching elements 304 and 306 such that power from the power source 202 is selectively applied to the stator coils of the motor 206 to cause rotation of the rotor. More particularly, to drive the motor 206, the motor controller 212 enables a first pair of a high-side power switching element 304 and a low-side power switching element 306 (e.g., by providing a voltage at the gate terminal of the power switching elements) for a first time period. In response to determining that the rotor of the motor 206 has rotated based on a pulse from the Hall effect sensor 210, the motor controller 212 disables the first pair of power switching elements and enables a second pair of a high-side power switching element 304 and a low-side power switching element 306. In response to determining that the rotor of the motor 206 has rotated based on a pulse(s) from the Hall effect sensor 210, the motor controller 212 disables the second pair of power switching elements and enables a third pair of a high-side power switching element 304 and a low-side power switching element 306. This sequence of cyclically enabling pairs of high-side power switching elements 304 and low-side power switching elements 306 repeats to drive the motor 206. Further, in some embodiments, the control signals include pulse width modulation (PWM) signals having a duty cycle that is set according to an amount of a trigger pull of the trigger 214 (as indicated by an output of the trigger 214) to control a speed or torque of the motor 206.

[0046] Generally, battery-powered power tools, such as power tool 100, can enter a standby or sleep mode when not in use for a period of time to reduce power consumption. Existing power tools can rely on active user interaction (e.g., trigger press, manual actuation input, etc.) to exit the standby or sleep mode and "wake up." This requirement for a positive action by the user can result in a delay or require the user to first remember to perform the required operation. The concepts described herein allow the power tool to recognize general user interaction (e.g., the user manipulating and / or moving the power tool) and automatically wake up the tool to allow the user to continue using the tool without having to first turn the tool on or perform some other type of positive action to exit the sleep mode. As described in more detail below, controller 212 can initiate a wake-up operation based on receiving input or other data from one or more accelerometers 216 and / or other wake-up sensors 218. In some embodiments, when acceleration above an acceleration threshold is detected using the accelerometer, power tool 100 enters a wake-up mode. In other embodiments, when the detected acceleration is sufficient to require a wake-up operation, accelerometer 216 will output a signal to controller 212.

[0047] Turning now to Figures 4A-4B According to one embodiment, a piezoelectric sensor 400 (e.g., a piezoelectric motion sensor, a piezoelectric accelerometer, etc.) is shown. In one embodiment, piezoelectric sensor 400 is used to determine when a wake-up operation is required, as described in more detail below. Further, while described as a single piezoelectric sensor, certain implementations of power tool 100 can include more than one piezoelectric sensor 400. Piezoelectric sensor 400 includes a spring-biased mass 402 and a crystal 404. Spring-biased mass 402 is in contact with crystal 404. When generally at rest (e.g., when power tool 100 is not in motion), the force that mass 402 exerts on crystal 404 is constant and minimal. In one embodiment, crystal 404 is a piezoelectric crystal such that when pressure is applied to the crystal by mass 402, a voltage is generated at output 406. Mass 402 is configured such that movement of the associated power tool 100 (such as in direction A) causes the mass to press against crystal 404, as Figure 4BAs shown, an output voltage is thereby generated due to the pressure applied to the crystal 404. In some embodiments, the output 406 is provided to the controller 212. The controller 212 can be configured to determine whether the voltage exceeds a predetermined value indicative that the power tool 100 has moved, thereby indicating that the user intends to use the power tool 100. In other embodiments, the piezoelectric sensor 400 can include circuitry for outputting a signal to the controller 212 to initiate a wake-up operation only when the amplitude of the signal (i.e., the amount of movement of the power tool 100) exceeds a predetermined value or threshold. As will be described in greater detail below, the controller 212 can initiate a wake-up operation based on the output of the piezoelectric sensor 400. In some examples, the power tool 100 can include multiple piezoelectric sensors 400 to allow for detection of movement in various directions and provide as input to the controller 212.

[0048] Turning now to Figures 5A-5B , according to some embodiments, a capacitive sensor 500 (e.g., a capacitive motion sensor, a capacitive accelerometer, etc.) is shown. In some embodiments, the capacitive sensor 500 is used to determine when a wake-up operation is needed, as described in greater detail below. The capacitive sensor 500 can include a spring-biased mass 502, where a spring 504 is oriented in a plane parallel to a desired direction of motion of the power tool 100. Thus, in some examples, multiple capacitive sensors 500 can be used to detect motion in one or more of the x-axis, y-axis, and z-axis of the power tool 100. The mass 502 can also be connected to a conductive plate 506. The capacitive sensor 500 is configured such that when the power tool 100 moves in a direction B parallel to the spring 504, the mass 502 pushes the plate 506 closer to a corresponding plate 508 in a fixed position, as shown in Figure 5B . The plates 506 and 508 form a parallel plate capacitor such that as the positions of the plates 506, 508 move relative to each other, the capacitance at the output 510 changes. This capacitance (or a subsequent current or voltage generated by the changing capacitance) can be provided to the controller 212. As described above, the controller 212 can be configured to determine whether the change in capacitance exceeds a predetermined value indicative that the power tool 100 has moved, thereby indicating that the user intends to use the power tool 100. In other embodiments, the capacitive sensor 500 can include circuitry for outputting a signal to the controller 212 to initiate a wake-up operation only when the amplitude of the signal (i.e., the amount of movement of the power tool 100) exceeds a predetermined value or threshold. As will be described in greater detail below, the controller 212 can initiate a wake-up operation based on the output of the capacitive sensor 500.

[0049] Turning now to Figures 6A-6BAccording to some embodiments, a mechanical sensor 600 (e.g., a mechanical motion sensor, a mechanical accelerometer, etc.) is shown. In some embodiments, the mechanical sensor 600 is used to determine when a wake-up operation is needed, as described in more detail below. The mechanical sensor 600 includes a spring-biased mass 602, with a spring 604 coupled to the spring-biased mass 602 oriented in a plane parallel to a desired direction of motion of the power tool 100 (e.g., the direction of motion to be detected). Thus, in some examples, multiple mechanical sensors 600 can be used to detect motion in one or more of the x-axis, y-axis, and z-axis of the power tool 100. The mass 602 can also be connected to a first conductive plate 606 or other conductive member. The mechanical sensor 600 is configured such that when the power tool 100 moves in a direction C parallel to the spring 604, the mass 602 moves the first conductive plate 606, which in turn causes the conductive plate to contact a second conductive plate 608, as shown in FIG. 6B, thereby generating an output indicative of movement of the power tool 100. For example, a voltage can be present on the first conductive plate 606 that can be passed via the second conductive plate 608 to the controller 212. In other examples, the contact between the first conductive plate 606 and the second conductive plate 608 can complete a circuit that generates a voltage or current value that can be input to the controller 212. In comparison to the piezoelectric sensor 400 and / or the capacitive sensor 500, the output of the mechanical sensor 600 is binary (e.g., the output is either on or off). Figure 6B

[0050] ​The above examples of sensors are exemplary in nature and are not intended to be limiting. Other sensor types can also be contemplated, such as electromechanical servo accelerometers, magnetic induction accelerometers, zero-balance accelerometers, optical accelerometers, pendulous integrating gyroscope accelerometers, resonant accelerometers, surface micromachined capacitive (MEMS) accelerometers, three-axis accelerometers, and / or other accelerometers as appropriate for a given application. Additionally, other sensors (such as wake-up sensors 218) can also be used in place of or in conjunction with accelerometers 216 to indicate that a wake-up operation is needed. Wake-up sensor 218 types can include pressure-based sensors, mechanical-based sensors, capacitive sensors, inductive sensors, other sensors as appropriate to indicate user manipulation of power tool 100. For example, in one embodiment, wake-up sensor 218 is an infrared sensor or an ultrasonic sensor configured to determine that a user's hand has covered wake-up sensor 218, thereby indicating that power tool 100 has been picked up or otherwise manipulated or handled. In other examples, wake-up sensor 218 can be a pressure sensor configured to generate an output to controller 212 based on detecting pressure provided by a user on power tool 100. For example, wake-up sensor 218 can be located in a handle or other portion of power tool 100 configured to be grasped by a user. As described below, the output of wake-up sensor 218 is configured to initiate a wake-up operation of power tool 100.

[0051] Turning to Figure 7 , a flowchart is described in accordance with some embodiments, illustrating a process 700 for performing a wake-up operation in power tool 100. In one embodiment, process 700 is performed by controller 212. At process block 702, controller 212 monitors input signals from one or more sensors, such as accelerometers 216 and / or wake-up sensor(s) 218. In some examples, controller 212 can be in a reduced power or standby operation (e.g., sleep) such that only minimal operations are performed, such as monitoring for user input via trigger 214 and / or wake-up sensor 218. At process block 704, controller 212 determines whether input has been received from accelerometers 216 and / or wake-up sensor 218 indicating that a wake-up operation is needed. In some examples, accelerometers 216 and / or wake-up sensor 218 can be configured to send a signal to controller 212 only when the value exceeds a predetermined threshold indicating sufficient movement. In other examples, controller 212 can receive direct input from accelerometers 216 and / or wake-up sensor 218 and determine whether the magnitude of the signal indicates that a wake-up operation is needed. For example, controller 212 can compare data received from accelerometers 216 and / or wake-up sensor 218 to a predetermined threshold.

[0052] In response to the controller 212 not receiving an input indicating that a wake-up operation is needed at process block 704, the controller 212 continues to monitor input signals from the accelerometer 216 and / or the wake-up sensor 218 at process block 702. In response to the controller 212 determining that an input has been received from the accelerometer 216 and / or the wake-up sensor 218 indicating that a wake-up operation is needed, the controller 212 determines whether the power tool 100 is currently in a standby or sleep mode at process block 706. In response to the controller 212 determining that the power tool 100 is not in a standby or sleep mode at process block 706, the controller 212 operates the power tool 100 in a normal operating mode. In response to the controller 212 determining that the power tool 100 is currently in a standby or sleep mode at process block 706, the controller 212 initiates a wake-up operation at process block 710. The wake-up operation can include various functions such as having the motor 206 ready to operate immediately or substantially immediately (e.g., within a millisecond, within two milliseconds, within five milliseconds, within 10 milliseconds, within 20 milliseconds, within 30 milliseconds, within 50 milliseconds, or other similar timeframe) upon receiving an input via the trigger 214, powering up a user interface and providing data to a user via the user interface, activating all circuits and programs associated with normal operation of the power tool, or other operations as needed for a given application. In one example, the controller 212 can initialize the power supply 202 and / or the motor drive circuit 204 such that there is no delay between a user actuating the trigger and motor rotation occurring. Initializing the power supply 202 can include closing one or more main power supply switches within the power supply to supply power to the motor drive circuit 204.

[0053] After initiating the wake-up operation at process block 710, the controller 212 starts a timer at process block 712. The timer can have a predefined value such as 30 seconds. However, values greater than 30 seconds or less than 30 seconds are also contemplated depending on the needs of a given application. At process block 714, the controller 212 determines whether an interrupt has been received. The interrupt can be an input from the trigger 214 such as a trigger actuation. The interrupt can also be a signal received via the user interface 220 such as a mode selection or other user input. Upon receiving an interrupt, the power tool 100 begins normal operation at process block 708.

[0054] In response to not receiving an interrupt, the controller 212 determines whether the timer has expired at process block 716. In response to the timer not expiring, the controller continues to determine whether an interrupt has been received at process block 714. In response to determining that the timer has expired, the controller 212 resumes the standby and / or sleep mode to conserve energy at process block 718. This can prevent accidental movement such as a user simply placing the power tool down from keeping the power tool in an operational state (e.g., wake-up mode).

[0055] Accordingly, the embodiments described herein provide, among other things, a wake-up sensor for a power tool. Various features and advantages will be set forth in the following claims.

Claims

1. A power tool characterized by comprising: comprising: a housing; a trigger; a sensor; a motor coupled to an output member; a motor drive circuit connected to the motor; and a motor controller connected to the motor drive circuit, the motor controller configured to: detect an input received from the sensor indicating that a wake-up operation is needed, determine whether the power tool is in a sleep state, and initiate the wake-up operation in response to detecting the input and determining that the power tool is in the sleep state.

2. The power tool of claim 1, wherein, the motor controller is further configured to: start a timer when initiating the wake-up operation; determine whether an interrupt signal is received at the motor controller; determine that the timer has expired; and resume the sleep state in response to the timer having expired and no interrupt signal being received.

3. The power tool of claim 2, wherein, the interrupt signal is actuation of the trigger.

4. The power tool of claim 1, wherein, the sensor is at least one selected from the group consisting of: an accelerometer, a piezoelectric sensor, and a capacitive sensor.

5. The power tool of claim 1, wherein, the wake-up operation is configured to prepare the motor for operation substantially immediately upon receiving a user input from the trigger.

6. The power tool of claim 1, wherein, the sensor is a pressure sensor configured to detect a user gripping the power tool.

7. The power tool of claim 1, wherein, the sensor is an ultrasonic sensor configured to detect a user's hand on the power tool.

8. A power tool characterized by comprising: a housing; a user interface; a sensor; a motor coupled to an output member; a motor drive circuit connected to the motor and configured to drive the motor in response to a drive signal received from the user interface; and a motor controller connected to the motor drive circuit, the motor controller configured to: receive an input from the sensor, determine whether the input received from the sensor exceeds a predetermined value, determine whether the power tool is in a sleep state, and initiate a wake-up operation in response to determining that the input received from the sensor exceeds the predetermined value and that the power tool is in the sleep state.

9. The power tool of claim 8, wherein, the motor controller is further configured to: start a timer when initiating the wake-up operation; determine whether an interrupt signal is received; determine that the timer has expired; and resume the sleep state in response to the timer expiring and no interrupt signal being received.

10. The power tool of claim 9, wherein, the interrupt is a user input received from the user interface.

11. The power tool of claim 8, wherein, the sensor is a piezoelectric sensor.

12. The power tool of claim 8, wherein, the sensor is a capacitive sensor.

13. The power tool of claim 8, wherein, the sensor is a mechanical accelerometer.

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