Patent Description:
Embodiments described herein relate to a trigger or other user input for electronic power tools.

<CIT> discloses a switching module for switching control current paths, in particular in vehicles. The actuating unit actuates a switching arm arranged in the switching module housing from a defined switching position into another defined switching position The switching element is arranged on the switching arm and the switching element switches the control current path without contact.

Input devices, such as a trigger on a power tool, may be physically coupled to one or more electronic components, such as variable resistors, relays, and the like. Physical connections on input devices, including triggers, may wear over time, thereby reducing the operational life of the tool. Thus, it would be advantageous to utilize contactless sensing device to reduce wear and increase life of the input devices and/or the power tool.

The invention provides a trigger assembly for a power tool according to claim <NUM>.

The sensor of the above trigger assembly may be configured to be in electronically coupled to a controller of the power tool, and the controller may be configured to control an output of the power tool.

The sensor of the above trigger assembly may also be configured to output a signal to the controller based on the sensed magnetic field.

The output of the sensor in the above trigger assembly may be a voltage indicative of a position of the trigger shoe.

According to the invention the magnet is an annular magnet configured to rotate based on movement of the arm.

The above trigger assembly, wherein the sensor may be configured to sense a change in the magnetic field of the annular magnet in response to the annular magnet rotating.

The above trigger assembly may further include a selector disposed on a surface of the housing. The trigger assembly may further include a pin including a first end that is engageable with the selector and a second end that is coupled to the selector magnet, and a selector sensor configured to sense a magnetic field of the selector magnet. The axial motion of the selector may be configured to rotate the selector magnet, thereby altering the magnetic field sensed by the sensor.

The above trigger assembly, wherein the selector sensor may be configured to sense a polarity of the selector magnet, and output a digital signal to the controller based on the sensed polarity.

The above trigger assembly, wherein the controller may be configured to execute an operating mode selected from a number of operating modes of the power tool based on the digital signal received from the selector sensor.

The above trigger assembly, wherein operating modes of the power tool may include a forward operating mode and a reverse operating mode.

In an additional embodiment, a method for controlling an output of an electric power tool is described, according to some embodiments. The method includes actuating a trigger shoe of the electric power tool in a first linear direction, wherein the actuation of the trigger shoe moves a movable plunger in the first linear direction. The method further includes converting the linear movement of the movable plunger into a rotation movement of a movable arm in a first rotational direction, and rotating an annular magnet coupled to the movable arm in the first rotational direction. The method also includes sensing a parameter of a magnetic field generated by the annular magnet at a first magnetic sensor and converting the parameter of the rotating magnetic field to an output voltage. The method also includes receiving, at a controller of the electric power tool, the output voltage, and controlling the output of the electric power tool based on the received output voltage.

The above method may also include the output of the electric power tool being a rotational speed.

The above method may also include the sensed parameter being a magnetic flux density vector component.

The above method may also include the first magnetic sensor being an analog rotational magnetic field sensor.

The above method may also include sensing a parameter of the magnetic field generated by the annular magnet at a second magnetic sensor, wherein the second magnetic sensor is a digital magnetic sensor.

The above method may also include initiating a wake-up process for the controller based on the controller receiving an output of the second magnetic sensor.

In another embodiment, a power tool is described. The power tool includes a trigger assembly. The trigger assembly includes a trigger shoe configured to be actuated in a first linear direction, wherein the actuation of the trigger shoe moves a movable plunger in the first linear direction. The trigger assembly further includes a movable arm configured to convert the linear movement of the movable plunger into a rotational movement of a movable arm in a first rotational direction, the movable arm further configured to rotate an annular magnet coupled to the movable arm in the first rotational direction. The trigger assembly also includes a magnetic sensor configured to sense a first parameter of a magnetic field generated by the annular magnet, wherein the magnetic sensor is configured to convert the magnetic field to an output voltage representative of a position of the trigger shoe. The power tool also includes a controller configured to receive the output voltage from the magnetic sensor and control the output of the power tool based on the received output voltage.

The above described power tool, wherein the output of the power tool may be a rotational speed.

The above described power tool may also include a second magnetic sensor configured to sense a second parameter of the annular magnet and transmit an output of the controller, wherein the second magnetic sensor is a digital magnetic sensor, and the second parameter is a polarity of the annular magnet.

The above described power tool, wherein the controller is further configured to initiate a wake-up process for the controller based on the controller receiving the output of the second magnetic sensor.

Other aspects of the embodiments will become apparent by consideration of the detailed description and accompanying drawings.

<FIG> illustrates an example power tool <NUM>, according to one embodiment. The power tool includes a housing <NUM>, a battery pack interface <NUM>, a driver <NUM> (e.g., a chuck or bit holder), and a contactless trigger assembly <NUM>. The power tool <NUM> may further have a mode selection device. For example, the mode selection device may be a forward-reverse selector <NUM>, which can allow a user to control the direction of a rotating portion of the tool. While <FIG> shows a specific power tool with a rotational output, it is contemplated that the herein described contactless trigger designs may be used with multiple types of power tools, such as drills, drivers, impact drivers, impulse drivers, saws (e.g. band saws, circular saws, miter saws, and the like), lights, hammer drills, nail guns, staple guns, liquid dispenser (e.g. caulk guns), crimping and/or clamping devices, or another type of power tool that uses a brushless DC motor that is controlled via a user input (e.g. a trigger).

<FIG> illustrates a cross-sectioned view of the power tool <NUM>, according to some embodiments. The contactless trigger assembly <NUM> (also referred as the trigger <NUM>) and the forward-reverse selector <NUM> (also referred to as the selector <NUM>) are types of user inputs to a controller associated with the tool <NUM>, as will be described below. For example, the trigger <NUM> may produce an analog signal indicative of a desired speed or torque that varies based on the travel distance of a trigger shoe <NUM>. For example, an analog magnetic sensor may be in communication with a magnet within the contactless trigger assembly <NUM>. The forward-reverse selector <NUM>, which may be considered part of the contactless trigger assembly, may be able to be moved from a first discrete position to a second discrete position. Similar to above, the forward-reverse selector <NUM> may include a magnet that is in communication with a magnetic sensor, such as a digital magnetic sensor, thereby outputting a signal to a controller of the tool <NUM> based on the position of the forward-reverse selector <NUM>. An example of such a controller is described further below (see motor controller <NUM> in <FIG>).

<FIG> and <FIG> illustrate a detailed view of the contactless trigger assembly <NUM>, according to some embodiments. The contactless trigger assembly <NUM> includes a housing <NUM> with a first housing section <NUM> and a second housing section <NUM> that are removably couplable to one another. The first housing section <NUM> includes rails <NUM> extending from a first surface <NUM> of the housing <NUM>. The first surface <NUM> of the housing <NUM> is defined by both the first housing section <NUM> and the second housing section <NUM> when the first and second housing sections <NUM>, <NUM> are coupled. The rails <NUM> are positioned to allow the trigger shoe <NUM> to slide along a length of the rails <NUM>, such that the travel distance of the trigger shoe <NUM> may be actualized. The first surface <NUM> of the housing <NUM> further includes a moveable plunger <NUM> extending therefrom. The moveable plunger <NUM> includes a first end <NUM> that is sized to be received by a circular recessed portion <NUM> of the trigger shoe <NUM>, such that the trigger shoe <NUM> and the moveable plunger <NUM> are coupled, providing in sync movement between the trigger shoe <NUM> and the moveable plunger <NUM>. The diameter of the circular recessed portion <NUM> is not significantly larger than the diameter of the moveable plunger <NUM>, allowing a tight fitting between the moveable plunger <NUM> and the trigger shoe <NUM>. In alternate embodiments, the moveable plunger <NUM> and the trigger shoe <NUM> may be coupled via alternate means such as fasteners, adhesive, or the like. In some examples, the housing <NUM> may be omitted, and the above components may be installed directly within the housing <NUM> of the tool <NUM>.

A second end <NUM> of the moveable plunger <NUM>, opposite the first end <NUM> of the moveable plunger <NUM>, is disposed in an internal portion <NUM> of the housing <NUM>. The first surface <NUM> includes a hole <NUM>, with an opening member <NUM> disposed in the hole <NUM>. The moveable plunger <NUM> is disposed in the opening member <NUM> such that the moveable plunger <NUM> slides on an annular surface <NUM> of the opening member <NUM>, with the first end <NUM> of the moveable plunger <NUM> being disposed externally of the housing <NUM> and the second end <NUM> of the moveable plunger <NUM> being disposed internally of the housing <NUM>. The second end <NUM> of the moveable plunger <NUM> includes a recessed portion <NUM> (see <FIG>) sized to receive a stationary rod <NUM> that is coupled to an internal surface <NUM> of the housing <NUM> that is opposite that of the first surface <NUM> of the housing <NUM>. As shown in <FIG>, the recessed portion <NUM> of the moveable plunger <NUM> includes a length that is sized to allow the moveable plunger <NUM> to move the travel distance, such that the trigger shoe <NUM> moves the travel distance.

With reference to <FIG> and <FIG>, a spring <NUM> is disposed on the stationary rod <NUM> and an external surface of the second end <NUM> of the moveable plunger <NUM>, with the spring <NUM> being disposed between a plate <NUM> of the stationary rod <NUM> and a cam <NUM> of the moveable plunger <NUM>. The plate <NUM> of the stationary rod <NUM> is directly coupled to the internal surface <NUM> of the housing <NUM>. The cam <NUM> of the moveable plunger <NUM> includes a diameter that is larger than the diameter of the spring <NUM>, such that the spring <NUM> biases a first surface <NUM> of the cam <NUM>. The cam <NUM> prevents the second end <NUM> of the moveable plunger <NUM> from exiting the internal portion <NUM> of the housing <NUM> due to the cam <NUM> having a larger diameter than that of the opening member <NUM>. The spring <NUM> biases the first surface <NUM> of the moveable plunger <NUM> along an axis A, such that a second surface of the moveable plunger <NUM> interfaces with the opening member <NUM>.

As illustrated in <FIG>, the internal portion <NUM> of the housing <NUM> further includes an annular magnet <NUM> coupled to the cam <NUM> of the moveable plunger <NUM> via an arm <NUM>. The arm <NUM> is moveably coupled to the cam <NUM> via a first pin <NUM> of the arm <NUM>. The arm <NUM> is also permanently coupled to the annular magnet <NUM> via a projection <NUM>. Accordingly, as the moveable plunger <NUM> moves along the axis A, the arm <NUM> is rotated about an axis B, which intersects the center of the annular magnet <NUM>, in a direction C. As the arm <NUM> rotates in the direction C, the annular magnet <NUM> also rotates in the direction C. Rotation of the annular magnet <NUM> alters the magnetic field detected by an analog magnetic sensor on a printed circuit board (PCB) <NUM> (see <FIG>). In some embodiments, the analog magnetic sensor is an analog rotational magnetic field sensor. The analog rotational magnetic field sensor may be configured to output a linear voltage to a controller of the tool <NUM> (see, e.g., motor controller <NUM> of <FIG>). The linear voltage may be indicative of a position of the trigger shoe <NUM>, and may be used to control an associated parameter of the tool <NUM>, such as the rotational speed of a motor. In other embodiments, the annular magnet <NUM> may also be in communication with a digital magnetic sensor. The digital magnetic sensor may be configured to transition from a first state to a second state based on detecting a change of the magnetic field produced by the annular magnet <NUM> in response to rotating as the trigger shoe <NUM> is depressed.

In other embodiments, the digital magnetic sensor outputs a first value when the rotation magnet produces a magnetic field indicative of the magnet being in a first predefined position (e.g. associated with a fully released trigger shoe <NUM>). The rotational magnetic sensor may then be configured to provide a second value when the magnet transitions away from the first predefined position. The transitional output of the digital magnetic sensor may provide an input to a controller of the tool <NUM> (see, e.g., motor controller <NUM> of <FIG>), which indicates that the controller should turn on (e.g., a wake-up signal). In still further embodiments, the annular magnet <NUM> may be in communication with only a digital magnetic sensor. For example, in some embodiments, where the tool <NUM> operates at a single speed or includes a separate speed adjusting mechanism (e.g., a speed dial), only a digital magnetic sensor is included to detect the annular magnet <NUM>.

Turning to <FIG>, when the trigger shoe <NUM> is in a relaxed state, the spring <NUM> biases the moveable plunger <NUM> and, thus, the trigger shoe <NUM>, to an extended position relative to the first surface <NUM> of the housing <NUM>. At this time, the annular magnet <NUM> is in a first position, with a first magnetic field relative to the PCB <NUM>, which the analog rotational magnetic field sensor detects. The first magnetic field detected by the analog rotational magnetic field sensor is then converted to a first output value, which is then received by a controller of the tool <NUM>.

Turning to <FIG>, when the trigger shoe <NUM> is depressed, the trigger shoe <NUM> moves the moveable plunger <NUM> along the axis A, such that the trigger shoe <NUM> moves toward the first surface <NUM> of the housing <NUM>. Movement of the moveable plunger <NUM> biases the spring <NUM> toward the plate <NUM> of the stationary rod <NUM>, thereby, also moving the cam <NUM> toward the plate <NUM>. This, in turn, causes the arm <NUM> to pivot about the axis B, rotating the annular magnet <NUM> about the axis B in the direction C. At this time, the annular magnet <NUM> is in a second position, with a second magnetic field relative to the PCB <NUM>, which the analog rotational magnetic field sensor detects. The second magnetic field detected by the analog rotational magnetic field sensor is then converted to a second output voltage that is distinct from the first output voltage, which is then received by the controller of the tool <NUM>.

With reference to <FIG>, when the force depressing the trigger shoe <NUM> is removed, the spring <NUM> biases the cam <NUM>, which moves the moveable plunger <NUM> and, thus, the trigger shoe <NUM>, along the axis A in a direction away from the first surface <NUM> of the housing <NUM>. Movement of the cam <NUM> causes the arm <NUM> to pivot about the axis B in a direction opposite to that of the direction C. The annular magnet <NUM> is therefore rotated in the opposite direction to that of the direction C until movement of the cam <NUM> is inhibited by the opening member <NUM>. At this time, the annular magnet <NUM> is in the first position, with the first magnetic field, which the analog rotational magnetic field sensor detects. The first magnetic field detected by the analog rotational magnetic field sensor is then converted to the first output voltage, which is then received by the controller of the tool <NUM>.

As illustrated in <FIG>, the contactless trigger <NUM> includes the forward-reverse selector <NUM>, as described above. A camming assembly <NUM> communicates with recessed portion walls <NUM> of the selector <NUM> via a selector arm <NUM> (see also <FIG>) that has a portion extending through an opening <NUM> (see also <FIG>) of the housing <NUM>. The opening <NUM> is defined by both the first housing section <NUM> and the second housing section <NUM>, on a second surface <NUM> of the housing <NUM> that is perpendicular to the first surface <NUM> of the housing <NUM>.

With reference to <FIG>, the selector arm <NUM> includes a center pin portion <NUM>, an intermediate portion <NUM>, and an upwardly extending portion <NUM>. The center pin portion <NUM> extends through the opening <NUM> of the housing <NUM>, such that the center pin portion <NUM> is positioned both in the internal portion <NUM> of the housing <NUM> and externally from the housing <NUM>. An end of the center pin portion <NUM> that is in the internal portion <NUM> of the housing <NUM> is coupled to a magnet <NUM>. The intermediate portion <NUM> is disposed externally of the housing <NUM> and is integrally connected to the center pin portion <NUM>. The intermediate portion <NUM> extends away from the opening <NUM> of the housing <NUM>, along the second surface <NUM>. The upwardly extending portion <NUM> is integrally connected to the intermediate portion <NUM> and is perpendicular to the intermediate portion <NUM>, such that the upwardly extending portion <NUM> extends away from the second surface <NUM>. The upwardly extending portion <NUM> includes a first side <NUM> and a second side <NUM> opposite the first side <NUM>, the first side <NUM> and the second side <NUM> are curved (shown in <FIG>).

A ball detent <NUM> is disposed in a recess in the internal portion <NUM> of the housing <NUM>. The ball detent <NUM> is biased toward an outside surface of the end of the center pin portion <NUM> via a ball detent spring <NUM> (see <FIG>). The outside surface of the center pin portion <NUM> includes a first recession <NUM>, a second recession <NUM>, and a third recession <NUM>, each sized to receive the ball detent <NUM>.

With reference to <FIG>, the selector <NUM> may move along an axis D in a first direction and a second direction, the second direction being opposite from the first direction. When the selector <NUM> moves along the axis D in the first direction, a first wall <NUM> of the recessed portion walls <NUM> of the selector <NUM> comes into contact with the first side <NUM> of the upwardly extending portion <NUM>. Since the first side <NUM> is curved, as the first wall <NUM> biases the first side <NUM>, the upwardly extending portion <NUM> rotates the intermediate portion <NUM> and, thus, the center pin portion <NUM>, about an axis E (see <FIG>, 10A), which extends through the center of the center pin portion <NUM>, in a direction F (see <FIG>). At this time, the ball detent <NUM> is moved out of the second recession <NUM>, which acts as a neutral positon, and along the outside surface of the center pin portion <NUM>. As the first wall <NUM> continues to bias the first side <NUM>, the center pin portion <NUM> continues to rotate. Continued rotation of the center pin portion <NUM> and, thus, the magnet <NUM>, is inhibited by the ball detent <NUM> being received in the first recession <NUM>, such that the center pin portion <NUM> is locked in a first position (shown in <FIG>).

When the selector <NUM> moves along the axis D in the second direction, a second wall <NUM> of the recessed portion walls <NUM> of the selector <NUM> comes into contact with the second side <NUM> of the upwardly extending portion <NUM>. Since the second side <NUM> is curved, as the second wall <NUM> biases the second side <NUM>, the upwardly extending portion <NUM> rotates the intermediate portion <NUM> and, thus, the center pin portion <NUM>, about the axis E in a direction opposite to that of the direction F. As the second wall <NUM> continues to bias the second side <NUM>, the center pin potion <NUM> continues to rotate. Continued rotation of the center pin portion <NUM> and, thus, the magnet <NUM>, is inhibited by the ball detent <NUM> being received in the second recession <NUM>, such that the center pin portion <NUM> is locked in the neutral position (shown in <FIG>). Continued force imparted by the second wall <NUM>, moves the ball detent <NUM> out of the second recession <NUM>, along the surface of the center pin portion <NUM>, and into the third recession <NUM>, where the center pin portion <NUM> is locked in a second position.

As the camming assembly <NUM> rotates between the first position and the second positon, the magnetic field of the magnet <NUM> varies relative to stationary elements of the assembly, such as the PCB <NUM>. This variation of the magnetic field is detected by a magnetic field sensor <NUM> located on the PCB <NUM>. In one embodiment, the magnetic field sensor <NUM> is a digital magnetic field sensor configured to transition from a first digital level to a second digital level based on the digital magnetic field sensor detecting a change in the magnetic polarity of the magnet <NUM>. The change in polarity is caused by the rotation of the magnet <NUM> and its associated poles.

In one example, the PCB <NUM> may extend out of a housing <NUM> of the contactless trigger assembly <NUM>. This configuration can allow the PCB <NUM> to extend into the tool <NUM>, thereby providing additional PCB space. For example, as illustrated in <FIG> and <FIG>, a portion of the PCB <NUM> extends downward out of the housing <NUM>.

<FIG> are a functional diagram illustrating the annular magnet <NUM> in communication with an analog magnet sensor <NUM> and a digital magnetic sensor <NUM>, according to some embodiments. In some embodiments, the analog magnet sensor <NUM> and the digital magnetic sensor <NUM> are both mounted on the PCB <NUM>, described above. In <FIG>, the annular magnet <NUM> is in a position associated with the trigger shoe <NUM> being in a fully released position. As shown, the analog magnetic sensor <NUM> is detecting a magnetic field generated by the annular magnet. As shown in <FIG>, the magnetic field is a result of the magnet flux received by the analog sensor based on the analog sensor <NUM> being located at an angle of ΘA from a centerline axis <NUM> of the annular magnet <NUM>. The digital magnetic sensor <NUM> detects a magnetic field based on the digital sensor <NUM> being located at an angle of ΘB from the centerline axis <NUM>. The digital magnetic sensor <NUM> may be an omnidirectional Hall effect sensor with a normally high state that goes low as the magnet transitions to a different polarity, thereby making the digital sensor <NUM> insensitive to strong external fields. The annular magnet <NUM> is shown to have two poles (for example, a north pole and a south pole). As shown in <FIG>, the boundary between the two poles bisects the diameter of the magnet. A similar magnet design is used in regards to the forward/reverse selector <NUM>.

<FIG> shows the annular magnet being in a position associated with the trigger shoe <NUM> being in a fully pulled positon. The annular magnet is now positioned such that the south pole of the magnet is positioned in proximity to the analog magnetic sensor <NUM>, such that the analog magnetic sensor <NUM> receiving a magnetic field based on the analog sensor being located at an angle of ΘA to the centerline <NUM>. Accordingly, the annular magnet is now positioned such that the north pole of the magnet is positioned in proximity to the digital magnetic sensor <NUM>, and is receiving a magnetic field based on the digital sensor <NUM> being located at an angle of ΘB to the centerline <NUM>. Both the analog sensor <NUM> and the digital sensor <NUM> may be rotational Hall effect magnetic sensors that are configured to measure a magnetic flux density vector component that enters the face of the sensor, and outputs either a linear proportional signal, or a digital signal. Thus, the magnetic sensors <NUM>, <NUM> are not being used to measure a flux based on a distance to a magnetic element. Rather, the magnetic sensors <NUM>, <NUM> measure an angle of the respective sensor to the magnet based on a received magnetic flux density vector component, thereby allowing the distance between the sensors <NUM>, <NUM> and the magnet to remain constant during operation.

<FIG> is a graph showing an example output of an analog magnetic sensor, such as magnetic sensor <NUM>, in relation to travel distance of the trigger shoe <NUM>. As shown in <FIG>, the output of the analog sensor increases in a generally linear fashion as the trigger shoe <NUM> moves from an initial relaxed position (depressed <NUM>) to a fully depressed position (depressed <NUM>), as shown by output trend line <NUM>. The particular voltage levels and travel distances are merely examples, as different levels and distances are used in other embodiments. Further, in some embodiments, the relationship between the travel distance of the trigger shoe <NUM> and the analog output of the magnetic sensor <NUM> is non-linear, such as logarithmic or exponential. In some embodiments, the output of the magnetic sensor <NUM> is a voltage. However, in other embodiments, the output is a current (e.g. <NUM>-20mA) or a digital value.

<FIG> is a graph showing an example output of a digital magnetic sensor, such as magnet sensor <NUM> and/or the digital magnetic sensor <NUM> used by the forward-reverse selector <NUM>. As shown in <FIG>, the output of the digital sensor varies between a digital high ("<NUM>"), and a digital low ("<NUM>"). As also shown in <FIG>, during a trigger pull, the digital magnetic sensor <NUM> transitions to a digital high when the trigger shoe <NUM> travel is approximately <NUM>. However, the digital magnetic sensor <NUM> may be configured to transition to a digital high when the trigger shoe <NUM> travel distance is less than <NUM> or greater than <NUM> in some embodiments. The digital sensor is further shown to transition back to a digital low during the release of the trigger shoe <NUM>. For example, the digital sensor <NUM> may transition back to a digital low when the trigger shoe <NUM> is within <NUM> of the fully released position. However, the digital magnetic sensor <NUM> may also be configured to transition to a digital low when the trigger shoe <NUM> is less than <NUM> of the fully released position, or more than <NUM> of the fully released position.

Similarly, a transition between a digital high and a digital low may also be output by the digital magnetic sensor <NUM> used by the forward-reverse selector <NUM>. For example, the digital magnetic sensor <NUM> may output a digital high when the forward-reverse selector <NUM> is in the first locked position. In other embodiments, the digital magnetic sensor <NUM> may output a digital high when the forward-reverse selector <NUM> is in the second locked position. In some embodiments, the digital magnetic sensor <NUM> may transition to a digital low signal when the forward-reverse selector <NUM> is moved out of either the first locked position or the second locked position, depending on the configuration of the tool. In other embodiments, the digital magnetic sensor <NUM> may only transition between digital states when the forward-reverse selector <NUM> is moved to one of the first or second locked positions. For example, the digital magnetic sensor <NUM> may transition to a digital high when the forward-reverse selector <NUM> is placed in the first locked position, and transition to a digital low when the forward-reverse selector is placed in the second locked position, or vice versa.

<FIG> is a graph showing an example output of a dual output digital magnetic sensor, such as the digital magnetic sensor <NUM> used by the forward-reverse selector <NUM> in some embodiments. As shown in <FIG>, the digital magnetic sensor <NUM> may be configured to output a first digital high at a first output when the forward-reverse selector <NUM> is in a first position, a second digital high at a second output when the forward-reverse selector <NUM> is in a second position, and a digital low on both the first output and the second output when the forward-reverse selector <NUM> is in a third position. For example, when the forward-reverse selector <NUM> is in the "forward" position, a first digital high <NUM> may be output via the first output of the digital magnetic sensor <NUM>. Conversely, when the forward-reverse selector <NUM> is in the "reverse" position, a second digital high <NUM> is output via the second output of the digital magnetic sensor <NUM>. Finally, if the forward-reverse selector <NUM> is in the "center" or locked position, there is a digital low at both the first output and the second output of the digital magnetic sensor <NUM>. The first and second outputs may be in communication with a controller via two or more I/O ports of the controller. As shown in <FIG>, the transitions to digital highs can be varied based on a desired amount of rotation of the magnet <NUM>. For example, a rotation of <NUM> degrees may be sufficient to cause a transition from the digital magnetic sensor <NUM>. However, rotations of more than <NUM> degrees or less than <NUM> degrees are also contemplated.

<FIG> illustrates a simplified block diagram of a brushless power tool, such as power tool <NUM>, according to some embodiments. The power tool <NUM> is shown to include a power source <NUM>, a power switching network <NUM>, a motor <NUM>, Hall-effect sensors <NUM>, a motor controller <NUM>, user input <NUM>, and other components <NUM> (e.g., battery pack fuel gauge, work lights [LEDs], current/voltage sensors, etc.). The power source <NUM> provides DC power to the various components of the power tool <NUM> and may be a power tool battery pack that is rechargeable and uses, for instance, lithium ion cell technology. In some instances, the power source <NUM> may receive AC power (e.g., 120V/<NUM> mains power) from a tool plug that is coupled to a standard wall outlet, and then filter, condition, and rectify the received power to output DC power. Each Hall-effect sensor <NUM> outputs motor feedback information, such as an indication (e.g., a pulse) when a magnet of the rotor rotates across the face of that Hall-effect sensor <NUM>. Based on the motor feedback information from the Hall-effect sensors <NUM>, the motor controller <NUM> can determine the position, velocity, and acceleration of the rotor.

In some embodiments, the motor controller <NUM> includes a memory storing instructions and an electronic processor coupled of the memory to retrieve and execute the instructions to thereby implement the functionality of the controller <NUM> described herein. The motor controller <NUM> is also configured to receive control signals from the user inputs <NUM>, such as by depressing the trigger shoe <NUM> or actuating the forward-reverse selector <NUM>. An output associated with the operation of the user inputs <NUM> may be provided to the motor controller <NUM> via the analog and digital magnetic sensors described above, such as analog sensor <NUM>, and digital sensors <NUM> and <NUM>. Examples of the control signals provided by the user inputs <NUM> are shown in <FIG> and <FIG>, described above. In some embodiments, the digital sensor <NUM> may provide a control signal (e.g., a digital signal) to the controller indicating a position of the forward-reverse selector <NUM>, which in turn instructs the controller <NUM> to operate the motor <NUM> in either a forward or reverse direction, which may be controlled via the power switching network <NUM>, as described below.

In response to the motor feedback information the control signals received via the user inputs <NUM>, the motor controller <NUM> transmits control signals to the power switching network <NUM> to drive the motor <NUM>, as explained in further detail with respect to <FIG>. In some embodiments, the power tool <NUM> may be a sensorless power tool that does not include a Hall-effect sensor <NUM> or other position sensors to detect the position of a rotor of the motor <NUM>. Rather, the rotor position may be detected based on the inductance of the motor <NUM> or the back electromotive force (emf) generated in the motor <NUM>. Although not explicitly illustrated, the motor controller <NUM> and other components of the power tool <NUM> are electrically coupled to the power source <NUM> such that the power source <NUM> provides power thereto.

<FIG> illustrates a circuit diagram of the power switching network <NUM>. The power switching network <NUM> includes a number of high side power switching elements <NUM> (e.g., field effect transistors [FETs]) and a number of low side power switching elements <NUM> (e.g., FETs). The motor controller <NUM> provides the control signals to control the high side FETs <NUM> and the low side FETs <NUM> to drive the motor based on the motor feedback information and user controls described above. For example, in response to detecting a pull of the trigger shoe <NUM> and the input from forward-reverse selector <NUM>, the motor controller <NUM> provides the control signals to selectively enable and disable the FETs <NUM> and <NUM> (e.g., sequentially, in pairs) resulting in power from the power source <NUM> to be selectively applied to stator coils of the motor <NUM> to cause rotation of a rotor. More particularly, to drive the motor <NUM>, the motor controller <NUM> enables a first high side FET <NUM> and first low side FET <NUM> pair (e.g., by providing a voltage at a gate terminal of the FETs) for a first period of time. In response to determining that the rotor of the motor <NUM> has rotated based on a pulse from the Hall-effect sensors <NUM>, the motor controller <NUM> disables the first FET pair, and enables a second high side FET <NUM> and a second low side FET <NUM>. In response to determining that the rotor of the motor <NUM> has rotated based on pulse(s) from the Hall-effect sensors <NUM>, the motor controller <NUM> disables the second FET pair, and enables a third high side FET <NUM> and a third low side FET <NUM>. This sequence of cyclically enabling pairs of high side FET <NUM> and low side FET <NUM> repeats to drive the motor <NUM>. Further, in some embodiments, the control signals include pulse width modulated (PWM) signals having a duty cycle that is set in proportion to the amount of trigger pull of the trigger shoe <NUM> (as indicated by the output of the magnetic sensor <NUM>), to thereby control the speed or torque of the motor <NUM>.

<FIG> is a process <NUM> for controlling the output of an electric power tool, such as power tool <NUM> is described, according to some embodiments. At process block <NUM> an input trigger of the electric power tool is actuated. For example, the input trigger may be the trigger shoe <NUM> described above. However, other input triggers such as pushbuttons, levers, and the like may also be used. In some embodiments, the input trigger is actuated in a first linear direction (e.g., a linear pulling of the trigger shoe <NUM>). At process block <NUM>, the linear actuation of the input trigger is converted to a rotational movement via one or more mechanical interfaces. In some embodiments, the linear motion of the input trigger is converted to a rotational movement using the contactless trigger assembly <NUM> described above. However, other configurations for converting the linear movement of the input trigger to a rotational movement are also contemplated.

At process block <NUM>, the rotational movement is transferred to a magnet of the electric power tool, such as annular magnet <NUM> described above. For example, the magnet may be coupled to the rotating arm <NUM> as described above. Thus, the magnet is rotated based on the actuation of the input trigger.

At process block <NUM>, an analog sensor detects variation in a magnetic field generated by the rotating magnet. In one embodiment, the sensor is a rotational Hall-effect magnetic sensor. The analog sensor may be configured to detect a change in a magnetic flux density component, which results from the rotation of the magnet. At process block <NUM>, the analog sensor converts the sensed magnetic field to an output signal, which may be provided to a controller, such as motor controller <NUM>, as described above. In some embodiments, the output of the analog sensor is a voltage that varies linearly with the rotation of the magnet as shown in <FIG>. However, in other examples, the output may be a non-linear output, such as a stepped output, a logarithmic output, etc..

At process block <NUM>, the controller <NUM>, upon receiving the output of the analog sensor, controls an output of the electric tool based on the received analog sensor output. For example, the motor controller <NUM> receives the output from the analog sensor <NUM> and drives the motor <NUM> by controlling the power switching network <NUM> based on the output from the analog sensor <NUM>, as described above. In one example, the motor controller <NUM> drives the power switching network <NUM> to control the output power to the motor <NUM> in a non-linear operation, as shown in motor drive profile <NUM> shown in <FIG>.

As shown in <FIG>, a first region <NUM> includes lower speeds that allow for more precise control by a user (e.g., through modulating the depressed amount of the shoe <NUM>). Subsequently, the second region <NUM> allows the tool to reach full speed earlier in the output range of the sensor (e.g. earlier in the trigger pull). As shown in <FIG>, the controller <NUM> may be configured to operate the output of the tool at <NUM>% power (e.g., with a pulse width modulated signal driving the power switching network <NUM> at <NUM> % duty ratio) when the trigger pull reaches <NUM>% of full travel. This arrangement enables the output of the tool to be at <NUM> % power across the tolerance range of the trigger shoe <NUM> or other input trigger. As described above, the output of the electric tool may be a rotational output, wherein the controller controls the rotational speed of the rotational output based on the received sensor output. In some embodiments, the controller also receives a control signal from the magnetic sensor <NUM> associated with the forward-reverse selector <NUM>. The motor controller <NUM> may then control the output of the power tool based on both the received output of the analog sensor <NUM> and the control signal from the magnetic sensor <NUM> to control the output of the tool at a desired output level and also in the desired direction.

In some embodiments, in block <NUM>, a digital magnetic sensor, such as digital magnetic sensor <NUM> senses the variation in the magnetic field in addition to or instead of the analog sensor. In these embodiments, the digital magnetic sensors convert the sensed magnetic field to a digital output, such as that shown in <FIG>, at process block <NUM>. Additionally, in process block <NUM>, the digital output may be received by the controller <NUM> of the electric tool to initiate certain functions, such as instructing the controller to "wake-up" or initialize in order to operate the tool. For example, if the digital magnetic sensors output a digital high to the controller, the controller <NUM> may "wake-up" or enter a normal mode from a "sleeping" or low-power mode. For example, the controller <NUM> may enter a low-power mode after the electronic tool has been inactive for a predetermined period of time (e.g. two hours). In some embodiments, as noted above, the analog sensor <NUM> is not included and the annular magnet <NUM> is in communication with only the digital magnetic sensor <NUM>. For example, in some embodiments, where the tool <NUM> operates at a single speed, includes a separate speed adjusting mechanism (e.g., a jigsaw with a speed dial), or is a tool that includes a cyclic motor operation that is enabled upon a trigger pull (e.g., a nailer or stapler), only the digital sensor <NUM> is included to detect the annular magnet <NUM>. Thus, the control signal from the digital sensor <NUM> to the motor controller <NUM> acts as an enable signal to the controller <NUM> and, in process step <NUM>, the controller <NUM> drives the motor <NUM> in response to receiving the enable signal from the digital sensor <NUM>.

<FIG> illustrate an alternative embodiment of a contactless trigger assembly <NUM>, such as contactless trigger assembly <NUM> described above. Similar to the contactless trigger assembly <NUM>, the contactless trigger assembly <NUM> includes a printed circuit board <NUM>, and an arm <NUM>. Similar to the contactless trigger assembly <NUM>, the arm <NUM> may be moveably coupled to a cam <NUM> of a moveable plunger <NUM>. As the moveable plunger <NUM> moves along the axis A, the arm <NUM> is rotated in direction C. The contactless trigger assembly <NUM> further includes a metallic member <NUM> coupled to the arm <NUM> at a pivoting cam <NUM>, and is configured to rotate with the arm <NUM>. In one embodiment, the metallic member <NUM> is constructed out of a ferrous material. In other embodiments, the metallic member <NUM> may be constructed out of a non-ferrous material. Example metallic materials may include iron, steel, aluminum, copper, and the like. An inductive coil <NUM> is coupled to the circuit board <NUM>, and is positioned between the circuit board <NUM> and the arm <NUM>. In some embodiments, an electrical current is provided to the inductive coil to generate a magnetic field.

As the arm <NUM> rotates in a direction C, the metallic member <NUM> also rotates in the direction C. As shown in <FIG>, the metallic member <NUM> and the inductive coil <NUM> are not contiguous annular shapes, but rather are curved arcs that, depending on the position of the movable plunger, overlap by a certain degree. Rotation of the metallic member <NUM> causes the amount of the ferrous member <NUM> to vary, thereby altering a strength of a magnetic field generated by the inductive coil <NUM>, which is in turn detected by a sensor on the printed circuit board <NUM>. The variance in the sensed magnetic field may be correlated to a position of the trigger. Sensing the strength of a varying magnetic field eliminates the need for a rotational magnetic field sensor. In one embodiment, the sensor is an analog rotational magnetic field sensor. In other embodiments, the sensor is an inductive sensor configured to sense the strength of the magnetic field generated by the inductive coil <NUM>.

As described above, the arm <NUM> rotates in a direction C along with the ferrous member <NUM>. As the arm <NUM> rotates the portion of the inductive coil <NUM> covered by the metallic member <NUM> changes. As shown in <FIG>, the trigger (not shown) is in the relaxed position causing the arm to be in a first position. In the first position, the metallic member <NUM> is positioned such that it covers the entire length of the inductive coil <NUM>. As the arm <NUM> moves due to a movement of the trigger into a second position as shown in <FIG>, the portion of the metallic member <NUM> covering the inductive coil <NUM> is reduced by a value proportional to the movement of the arm <NUM>. As the arm <NUM> reaches the maximum travel position, as shown in <FIG>, the portion of the metallic member <NUM> covering the inductive coil <NUM> is further reduced. By reducing the amount of the inductive coil <NUM> covered by the inductive member <NUM>, a magnetic field is varied, which is detected by the sensor. The sensor is configured to provide an output to a controller, such as motor controller <NUM>, representative of the sensed inductive value, which may then be used to control an output of a power tool, such as described above.

<FIG> illustrates an alternative embodiment of the contactless trigger assembly <NUM> as contactless trigger assembly <NUM>. The components and operation of the trigger assembly <NUM> are similar to that of trigger assembly <NUM>, and it is understood that the components and operation of the contactless trigger assembly <NUM> are the same as those in contactless trigger assembly <NUM>, unless noted otherwise below. As shown in <FIG>, the inductive coil <NUM> is positioned such that no part of the metallic member <NUM> covers the inductive coil <NUM> when the trigger is in the relaxed position (e.g. not depressed). In <FIG>, the trigger (not shown) is in the relaxed (e.g. not depressed) position causing the arm to be in a first position. In the first position, the metallic member <NUM> is positioned such that it does not cover any portion (or a minimal portion) of the inductive coil <NUM>. As the arm <NUM> moves due to a movement of the trigger into a second position as shown in <FIG>,the portion of the metallic member <NUM> covering the inductive coil is increased by a value proportional to the movement of the arm <NUM>. As the arm <NUM> reaches the maximum travel position, as shown in <FIG>, the portion of the metallic member <NUM> covering the inductive coil <NUM> is further increased. By increasing the amount of the inductive coil <NUM> covered by the metallic member <NUM>, a magnetic field value is varied, which is detected by a sensor on the printed circuit board <NUM>. The sensor is configured to provide an output to a controller, such as motor controller <NUM>, representative of the sensed magnetic field value, which may then be used to control an output of a power tool, such as described above.

In some embodiments, the inductive coil <NUM> of trigger assembly <NUM> and/or trigger assembly <NUM> may be configured to include multiple receiving traces or conductors that are sinusoidal in shape, but offset by <NUM>°, so that when the metallic member <NUM> rotates, the voltage induced in one of the traces/conductors is a sine wave and the voltage in the other trace/conductor is a cosine wave. The voltage output of the two traces/conductors is sensed by a sensor, such as a TX Sine Cosine sensor, and can then be provided to a controller, such as motor controller <NUM>. The motor controller <NUM> may then determine a location (e.g. rotational angle) of the metallic member <NUM> with respect to the traces/conductors of the inductive coil <NUM>. In some embodiments, the angle is generated by the motor controller <NUM> using an arctangent function, <MAT>. In some embodiments, the sine-cosine sensor can achieve a resolution of approximately <NUM>° for detecting the position of the metallic member <NUM>, and a detection accuracy of greater than <NUM>%.

Claim 1:
A trigger assembly (<NUM>) for a power tool (<NUM>) comprising:
a housing (<NUM>);
a moveable plunger (<NUM>) extending from a surface (<NUM>) of the housing, the moveable plunger including a first end (<NUM>) disposed externally from the housing and a second end (<NUM>) disposed internally within the housing;
a trigger shoe (<NUM>) coupled to the first end of the moveable plunger;
an arm (<NUM>) including a first side that is moveably connected to the second end of the moveable plunger and a second side that is coupled to an annular magnet (<NUM>); and
a sensor (<NUM>) configured to sense a magnetic field of the annular magnet,
wherein movement of the trigger shoe rotates the annular magnet about a central axis (B) of the annular magnet and alters the magnetic field sensed by the sensor.