Light emission circuit and method for a handheld tool

Abstract

A rotary tool includes a light-emitting element and a control circuit for the light-emitting element. The light-emitting element may comprise one or more light-emitting diodes arranged at least partially within a nose cap of the rotary tool. The illumination of the light-emitting element may be controlled by a method for operating the control circuit.

Description

Field of TechnologyThe present disclosure relates to power tools and, more particularly, to hand-held rotary tools.Prior ArtRotary tools provide users with an effective means of performing detail work. However, it may occur that the working environments of these tools are not always optimal in view of the vision conditions for observing the work. For example, lighting conditions may be anything other than ideal, or work may be required at a location where traditional and overhead lighting is difficult.What is desired is a rotary tool having an ergonomic working light mounted on the tool for direct light output to the workpiece under any desired condition. Even more advantageous would be a rotary tool having a light with additional controllable features to create the conditions desired for the user.SummaryOne aspect of this disclosure is directed to a light emitting circuit for a handheld tool, the circuit comprising at least three nodes. The first node provides a first input voltage reference. The second node provides a second input voltage reference, the second node being separated from the first node by a capacitor. The third node is separated from the first node by a diode that restricts the current flow between the first node and the third node, and the third node is also separated from the second node by a capacitor parallel to a light emitting branch. The light emission branch comprises a first sub-branch with a light emitting element and a second sub-branch with a transistor arrangement. The light emitting element may include one or more light emitting diodes (LEDs). The transistor arrangement may include one or more bipolar transistors (BJTs).Another aspect of this disclosure is directed to a light emitting circuit for a handheld tool, the circuit including 4 nodes, a first input voltage reference, a second input voltage reference, a light emitting diode (LED) arrangement, and a transistor arrangement. The first node is connected to the first input voltage reference. The second node is connected to the second input voltage reference and separated from the first node by a first capacitor. The third node is separated from the first node by a zener diode that limits current flow between the first node and the third node. The third node is further separated from the second node by a second capacitor and a light emission branch including the LED array and the transistor array. The capacitor and the light emission branch are parallel. The fourth node is disposed in the light emission branch, wherein the fourth node is separated from the third node by the LED array and is separated from the second node by a sub-path of the transistor array. The transistor arrangement includes a pair of bipolar transistors (BJTs), wherein the collector of a first BJT is connected to the fourth node, the base of the first BJT is connected to the collector of a second BJT, and the emitter of the first BJT is connected to the base of the second BJT and is separated from the second node by a resistor. The collector of the second BJT is separated from the third node by a resistor, and the emitter of the second BJT is connected to the second node.Another aspect of this disclosure is directed to a rotary tool comprising: a body; an electric motor disposed at least partially within the body; a rotating shaft coupled to the electric motor; a nose cap having electrical contacts and at least partially surrounding the rotating shaft during operation of the rotary tool; and a switch in electrical communication with the electrical contacts of the nose cap. The electric motor is configured to rotationally drive the rotating shaft. The switch activates and deactivates the electric motor. The nose cap further includes a light emitting diode (LED) disposed thereon, the LED illuminating when the electric motor is activated, the LED configured to project light toward a working end of the rotating shaft when illuminated.Another aspect of this disclosure is directed to a method of controlling a light emitting diode (LED) disposed on a rotary tool. The method includes steps of applying a voltage to a control circuit in response to activation of an electric motor of the rotary tool, using the voltage to illuminate the LED, and lighting the LED after the control circuit detects a turn-on condition until the control circuit detects a turn-off condition. The activation of the electric motor is controlled via a switch. The control circuit comprises a transistor arrangement.The above aspects of this disclosure and other aspects will be described in more detail below with reference to the attached drawings.Brief Description of the DrawingsFIG. 1 is a schematic illustration of a rotary tool. FIG. 2 is a close-up view of particular elements of the rotary tool of FIG. 1. FIG. 3 is a circuit diagram of a lighting control circuit for a rotary tool. FIG. 4 is a circuit diagram of a lighting control circuit for a rotary tool and shows particular features thereof. FIG. 5 is an illustration of a physical configuration of the circuit board of FIG. 4 on a circuit board for placement in the nose cap of a rotary tool. FIG. 6 is a flow chart illustrating a method of use for controlling tool-unique illumination features of a rotary tool. FIG. 7 is a flow chart illustrating a method of use for controlling tool-unique illumination features of a rotary tool. FIG. 8 is a first timing diagram illustrating an operating method for the tool's own illumination features of a rotary tool. FIG. 9 is a second timing diagram illustrating an operating method for the tool's own illumination features of a rotary tool.DETAILED DESCRIPTIONThe illustrated embodiments are disclosed with reference to the drawings. It should be understood, however, that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of the particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art to practice the disclosed concepts.FIG. 1 is a schematic illustration of a rotary tool 100 according to an embodiment of the teachings disclosed herein. The rotary tool 100 comprises a body 101 which houses an electric motor 103. The electric motor 103 simplifies the primary operation of the rotary tool 100 by using energy from an energy source 105. In the depicted embodiment, the power source 105 includes an electrical cable connected to an external electrical power source, such as a power outlet or a power transformer, but other embodiments may include other configurations without departing from the teachings disclosed herein. Other embodiments may include a cordless configuration with a battery without departing from the teachings disclosed herein. In the depicted embodiment, a user may grasp the rotary tool 100 on the body 101 or may grasp it on the neck 111 (with so-called "pencil grip") for finer motor control during operation.FIG. 2 shows a close-up view of additional features of the operating elements of the rotary tool 100. In this figure, a tool bit 201 is rotated by a rotating shaft 203 rotationally driven by the electric motor 103 (not shown, see FIG. 1 ). In the depicted embodiment, the tool bit 201 includes a cutting disk, but other embodiments may include any other rotary tool bit known to those skilled in the art without departing from the teachings disclosed herein. The tool bit 201 is held in position with respect to the rotating shaft 203 via a holder 211. The rotating shaft 203 and the holder 211 project out of the body 100 through a nose cap 213 defining an end of the body 101 closest to the tool bit 201 during operation of the rotating tool 100.In the depicted embodiment, power to the electric motor 103 is controlled via a switch 215. Other functions may be controlled via the switch 215 or other switches or controls (not shown) of the rotary tool 100 without departing from the teachings disclosed herein.In the depicted embodiment, the nose cap 213 additionally includes a number of light emitting diodes (LEDs) 223 disposed at least partially thereon. The LEDs 223 are configured to illuminate with power provided by a power source 105 (see FIG. 1 ) during operation of the rotary tool 100. The lighting of the LEDs 223 is directed to the tool attachment 201 to provide light to a user while operating the rotary tool 100. In the depicted embodiment, the LEDs 223 are disposed on the nose cap 213 at regular angular distances from the rotating shaft 203, but other embodiments may include different arrangements without departing from the teachings disclosed herein. In the depicted embodiment, the rotary tool 100 includes a plurality of 4 LEDs 223, but other embodiments may include a different number of LEDs 223 without departing from the teachings disclosed herein.While the depicted embodiment includes a plurality of light emitting diodes, other embodiments may include other light emitting elements without departing from the teachings disclosed herein. In such embodiments, the rotary tool 100 may include incandescent lamps, point lasers, rotary lasers, compact fluorescent light, compact neon light, or other light emitting elements known to those of ordinary skill in the art without departing from the teachings disclosed herein.In the depicted embodiment, the LEDs 223 are each controlled by a control circuit (not shown; see FIGS. 3-5 ) and may be illuminated in response to detection of an enable condition until detection of a disable condition. For example, and not limited to, an activation condition may include activation of the electric motor 103, and a deactivation condition may include deactivation of the electric motor 103. In such embodiments, one or more of the LEDs 223 may / may be extinguished (i.e., cease emitting light) in response to deactivation of the electric motor 103.Some users would instead perhaps prefer separate control over the operation of the rotary tool 100 and also over the lighting state of the one or more LEDs 223. In the depicted embodiment, the lighting state of the LEDs 223 may be controlled based on the user's operation behavior upon operation of the switch 215. For example, and not limited to, the switch 215 may include a push switch, and the LEDs 223 only light when the electric motor 103 is activated with "long press" of the switch 215, such as when the user presses the switch 215 for a minimum time threshold. In such embodiments, activation of the electric motor 103 with "short pressure" would include activation of the switch 215 for a time less than a predetermined amount of time. In response to a short press, the electric motor 103 may turn on, but the LEDs 223 would not illuminate. In such embodiments, activation of the electric motor 103 with "long pressure" would result in both the electric motor 103 and one or more of the LEDs 223 being turned on.Other embodiments may exhibit the reverse behavior without deviating from the teachings disclosed herein. In such embodiments, a user may illuminate one or more of the LEDs 223 via a "short press" while a "long press" may activate the electric motor 103 without illuminating any of the LEDs 223. In some such embodiments, one or more of the LEDs 223 may light up with "long press" in response to an initial activation and then may light up at the end of the long press (i.e., upon reaching the time threshold for the continuous operation of the switch 215).The time threshold for delimiting a "short press" from a "long press" may be predetermined constructively. In the depicted embodiment, a threshold of 3 seconds is used, but other embodiments may include other thresholds without deviating from the teachings disclosed herein. The time threshold may be preselected as any value between 1 and 5 seconds, for example, and not limited thereto, without departing from the teachings disclosed herein.Other embodiments may include other configurations of the LEDs 223 without departing from the teachings disclosed herein. For example, and not limited to, additional behaviors of the LEDs 223, such as changes in the level of brightness, activation of only a portion of the plurality of LEDs, blinking or flashing patterns, or other known lighting behaviors, may be realized without departing from the teachings disclosed herein. In some embodiments, different behaviors may be realized in response to a predetermined number of press operations of the switch 215 according to a preprogrammed sequence. In such embodiments, the behavior of each LED may be determined based on how many actuations of the switch 215 a user is making, and the behaviors may be rotationally proceeding according to a preprogrammed sequence. In such embodiments, in response to the same number of actuations of the switch 215, all of the LEDs 223 may behave independently, or two or more LEDs 223 may behave identically without departing from the teachings disclosed herein.The switch 215 may include a toggle switch, potentiometer, step potentiometer, or a transmitter for a microcontroller without departing from the teachings disclosed herein. Specifically, although the switch 215 selectively controls the behavior of the LEDs 223, the electric motor 103 of the rotary tool 100 should operate regardless of the state of the LEDs 223. In some embodiments, such as using a passive toggle switch configuration of the switch 215, the illumination of one or more LEDs 223 may depend on the state of activation of the electric motor 103 without deviating from the teachings disclosed herein. In some embodiments, a control mechanism other than switch 215, such as a second switch, a button, a body heat activated thermal switch, or other known mechanism, may be used to control LEDs 223 without departing from the teachings disclosed herein. In some embodiments having a second control mechanism for LEDs, the second control mechanism may be at least partially disposed within the nose cap 213 without departing from the teachings disclosed herein.The control of the behavior of the LEDs 223 relies on a control circuit (not shown). FIG. 3 is an illustration of a particular embodiment of a control circuit for LEDs in a hand-held tool (as in rotary tool 100; see FIGS. 1, 2 ). The control circuit comprises a first input voltage reference 301 and a second input voltage frequency 303. The first input voltage reference 301 may also be referred to as a "high input voltage reference" or simply a "high input voltage". The second input voltage reference 303 may also be referred to as a "low input voltage reference" or simply a "low input voltage". In the depicted embodiment, the circuit includes a first node 305, a second node 307, a third node 309, and a fourth node 311. The nodes each provide a reference point for a particular voltage value for electrical junctions associated with the node and are introduced herein for purposes of simplified discussion of the circuit.Functionally, the light emitting functions of the circuit are achieved by elements of a light emitting branch 321 comprising a first sub-branch 323 consisting of light emitting elements (hereinafter "light emitting" (LE) arrangement 323) and a second sub-branch 325 consisting of a transistor arrangement (hereinafter "transistor arrangement" 325) suitable for controlling the lighting behaviour of the LE arrangement 323. The LE arrangement 323 comprises a first high-side terminal (high pin) 333 (hereinafter "high-side LE terminal" 333) connected to the third node 309 and a first low-side terminal (low pin) 335 (hereinafter "low-side LE terminal" 335) connected to the fourth node 311. The transistor arrangement 325 comprises a second low-side terminal 337 (hereinafter "low-side TA terminal" 341) connected to the second node 307. The transistor array 325 also includes a plurality of second high-side terminals (hereinafter "high-side TA terminals"). In the depicted embodiment, these comprise a high-side TA terminal 339 and a high-side TA terminal 341. The high-side TA terminal 339 is connected to the third node 309, and the high-side TA terminal 341 is connected to the fourth node 311.The control circuit includes additional elements to control undesired behaviors of voltage and current in the circuit. The second node 307 is separated from the first node 305 and the third node 309 by capacitors 351. The capacitors 351 aid in dissipation of high frequency currents away from the light emission branch 321, which may reduce unwanted flickering or flashing of the LE array 323. The capacitors 351 may have different capacitance values or identical values without departing from the teachings disclosed herein.In addition, the first node 305 is separated from the third node 309 by a diode 353 to protect the light emitting branch 321 from an undesired current flow. In the illustrated embodiment, diode 353 includes a zener diode that allows current to flow only from first node 305 to third node 309, which in turn protects the elements of LE array 323 and transistor array 325, as well as prevents unwanted behaviors of the sub-branches of light emission branch 321 that may be caused by current flow in an unwanted direction. In the depicted embodiment, diode 353 may comprise a zener diode, but other embodiments may comprise other configurations without departing from the teachings disclosed herein.The circuit of Figure 3 provides a generalized structure for the light control functions. FIG. 4 is a circuit diagram for a similar control circuit having particular configurations for the LE array 323 and transistor array 325.In the depicted embodiment, the LE array 323 includes a plurality of LEDs 223 (see also FIG. 2 ). In this embodiment, the LE array 323 includes 4 LEDs 223 arranged such that two series-connected LEDs 223 include one sub-path of the array in parallel with another identical sub-path. Other embodiments may include other arrangements, including arrangements with a different number of LEDs 223, without departing from the teachings disclosed herein. Other embodiments may include light emitting elements in addition to or different from LEDs 223 without departing from the teachings disclosed herein. Such embodiments may also include incandescent lamps, point lasers, rotary lasers, compact fluorescent light, compact neon light, or other light emitting elements known to those of ordinary skill in the art, instead of or in addition to light emitting diodes, without departing from the teachings disclosed herein.In the depicted embodiment of FIG. 4, the TA array 325 includes a plurality of transistors 425. In the depicted embodiment, each of the transistors 425 includes a bipolar transistor (BJT), but other embodiments may include other configurations without departing from the teachings disclosed herein. Transistor array 325 also includes a number of impedances 427 to provide control over the voltage dropped across various elements of transistors 425. The impedances 427 comprise resistors in the depicted embodiment, but other embodiments may use other reactance impedances without deviating from the teachings disclosed herein.In the illustrated embodiment, a first bipolar transistor (BJT) 425 ais connected to the fourth node 311 at the collector terminal via the high-side TA terminal 341. The base terminal of the first BJT 425 ais connected to the collector terminal of the second BJT 425 band separated from the third node 309 by the resistor 427 a. The emitter terminal of the first BJT 425 ais connected to the base terminal of the second BJT 425 band separated from the second node 307 by the resistor 427 b. The emitter terminal of the BJT 425 bis connected to the second node 307 via the low-side TA terminal 337. This configuration of the transistor arrangement 325 results in a controlled and continuous current consumption via the transistor arrangement 325. Due to this continuous current consumption, a continuous voltage is applied to the LED array 323, and there is continuous current consumption over the entire light emitting arm 321. This continuous current consumption advantageously leads to a steady illumination of the LEDs 223 and ensures ergonomic and reliable light emission.The circuit diagrams of FIGS. 3 and 4 are shown to provide a better understanding of the electrical connections, node voltage analysis, and current flow analysis, but do not limit the structure or topology of the circuit. FIG. 5 shows an illustration of a circuit board 501 suitable for implementation with a rotary tool (such as rotary tool 100; see FIG. 1 ). The circuit board 501 includes the same topology of electrical connections as shown in the circuit diagram of FIG. 4, but is constructed in a manner suitable for use in an associated rotary tool. The view of FIG. 5 includes a plan view of the layout of the circuit board 501 with the elements mounted thereon. In the depicted embodiment, the circuit board 501 includes a printed circuit board (PCB) with the electrical connections routed on both sides of the circuit board (not shown), but other embodiments may include other configurations without departing from the teachings disclosed herein. In the depicted embodiment, the circuit board 501 is configured to be disposed in a nose cap of a rotary tool (such as in the nose cap 213; see FIG. 2 ). In such embodiments, the associated nose cap may include a retaining member (not shown) to securely retain the placed circuit board 501 in position within the nose cap. This holder advantageously protects the internal elements of the rotary tool 501, including the circuit elements of the circuit board 501. The circuit board 501 is also constructed with a void 503 configured to receive a rotating shaft of a rotating tool (such as the rotating shaft 203; see FIG. 2 ). The void 503 houses a mechanical connection between a rotating shaft of a rotary tool and a driving member (such as the electric motor 103; see FIG. 1 ). Other embodiments may include other arrangements without departing from the teachings disclosed herein.FIG. 6 is a flow chart showing a method of utilizing the light emission functions of a rotary tool (such as rotary tool 100; see FIG. 1 ) with a control circuit (such as the circuit of FIG. 3 ). The method begins in step 600 with the detection of an activation condition. In the depicted embodiment, the engagement condition may include activation of the motor of the rotary tool, actuation of a switch, or a combination of both. In the depicted embodiment, the motor of the associated rotary tool may be an electric motor powered via an electrical power source, and the power source may also provide the required electrical signal to a control circuit of the rotary tool. After the activation condition has been detected, a light emission branch of the control circuit is activated and the associated light emitting elements are activated, i.e. illuminated. The light emitting elements include light emitting diodes (LEDs) in this embodiment, but other embodiments may include other configurations without departing from the teachings disclosed herein.After illumination, the method proceeds to step 604, where the circuit monitors the process for a shutdown condition. In the depicted embodiment, the shutdown condition may include deactivation of the electric motor or the switch. The shutdown condition may also include a "long press" of the switch, which is interpreted to cause the LEDs to be extinguished without deactivating the electric motor of the rotary tool. A "long press" is achieved by continuously actuating the associated switch beyond a predetermined time threshold. In the depicted embodiment, the predetermined time threshold may be 3 seconds, but other embodiments may include other configurations without departing from the teachings disclosed herein. This behavior of the control circuit may be effected by a transistor arrangement, such as the transistor arrangement 325 (see FIGS. 3 ; 4 ), but other embodiments may include other configurations without departing from the teachings disclosed herein.Once a shutdown condition has been detected, the method proceeds to step 606 where the LEDs are turned off, i.e., extinguished, and the method ends. In some embodiments, the method may loop back to step 600 to again identify an enable condition upon completion, such as when a user continues to actively use the rotary tool without illumination.FIG. 6 illustrates a first embodiment of lighting behavior, but more sophisticated functions may be desired. FIG. 7 shows an illustration of an illumination method with additional features.The method begins with step 700 in which an activation condition has been detected. In the depicted embodiment, the power-on condition includes applying a voltage to the circuit in substep 700 aand activating a switch in substep 700 b. Other embodiments may include a different set of engagement conditions or an alternative configuration of engagement conditions. An alternative embodiment may, for example and not limited to, initiate the method in response to only one of substeps 700a, 700b, respectively, without departing from the teachings disclosed herein.After the activation condition is detected, a timer is triggered in step 702, and the method waits for a first-time threshold value to be reached in step 704. If the threshold has not yet been reached, the method continues with step 706 to determine whether the switch is still activated. If the switch is not activated, the method ends, but if the switch is still activated, the method returns to step 704 to remeter the timer. After the first threshold is reached, the method proceeds to step 708 to illuminate a light emitting element of the rotary tool, a light emitting diode (LED) in this embodiment. Other embodiments may include other light emitting elements without departing from the teachings disclosed herein. In the depicted embodiment, the first threshold may comprise a time window of 1-5 seconds, such as 3 seconds, but other embodiments may comprise other values for the first threshold without deviating from the teachings disclosed herein.After the LED is illuminated, an intensity loop 710 sub-process is initiated to adjust the intensity or visual brightness of the illumination. The thread first checks in step 711 whether the switch is still activated, and if not, the thread 710 is ended and the method moves on to the next step. However, as long as the switch is still activated, the sub-process continues with substep 713 to check whether the timer has exceeded a next threshold. In the depicted embodiment, thresholds may be exceeded at regular time intervals, such as every 1-5 seconds. Each next threshold beyond the first threshold (of step 704) may include, for example, and not limited to, a 1 second time window, but other embodiments may include other configurations without departing from the teachings disclosed herein. If the switch remains activated beyond the next threshold, the sub-process continues to substep 715 where it is determined whether the LED is already lighting at maximum intensity. If not, the luminous intensity is increased in substep 717. If the maximum intensity is reached, the sub-process instead causes the LED to light up in substep 719.After the intensity change in either substep 717 or 719, the substep returns to substep 711. This sub-process 710 loops through the steps iteratively advantageously as long as the user activates the switch, resulting in a continuous sequence of intensity changes including minimum intensity, maximum intensity and "OFF". The intensity changes advantageously take place at regular intervals as long as the switch is activated.In the depicted embodiment, each intensity increase may correspond to a percentage increase in light energy power. For example, and not limited to, there may be 4 intensity intervals in a rotary tool that include 4 separate LEDs, each intensity interval corresponding to turning on another one of the 4 LEDs. In another embodiment, each intensity interval may correspond to a 10% increase in light energy power without deviating from the teachings disclosed herein. In such an embodiment there may be 10 intensity levels in sequence. In other embodiments, each intensity interval may correspond to a different light emission pattern between multiple LEDs. For example, and not by way of limitation, some such embodiments may illuminate a single LED in an array of 4 LEDs before different pairings of the 4 are illuminated before ultimately all 4 LEDs are simultaneously illuminated. This configuration can advantageously provide different desirable light distributions that better illuminate a workpiece during operation of the rotary tool. Other embodiments may include programmable intensity settings without deviating from the teachings disclosed herein. The number of intensity levels, the sequence of intensity levels, or the temporal thresholds for selecting a corresponding intensity level may be virtually arbitrary in such embodiments and selected by a user or manufacturer without deviating from the teachings disclosed herein.Once it is detected in substep 711 that the switch is no longer activated, the method exits the thread of intensity loop 710 and continues to step 720, where the tool waits for a shutdown condition to be detected. In the depicted embodiment, the shutdown condition includes either removing the voltage applied to the circuit (such as disabling the power source for the rotary tool) or reactivation of the switch. In some alternative embodiments, with reactivation of the switch, a return to one of the substeps of intensity loop 710 may be made without deviating from the teachings disclosed herein. Once the shutdown condition is detected, the method causes the LED to light-off in step 722. If the LED has already extinguished (as via substep 719), this step acts as a place holder step to ensure that the LED is turned off under other conditions. Following step 722, the method ends with step 724. However, after the end of the method, in the depicted embodiment, the method may return to step 700 to again identify engagement conditions, such as when the motor of the rotary tool is being used further in the unlit state. Other embodiments may not return to the initial step 700 without departing from the teachings disclosed herein.FIG. 8 illustrates a timing diagram illustrating the behavior of a rotary tool (such as rotary tool 100; see FIG. 1 ) in accordance with an embodiment of the inventions disclosed herein. The timing diagram includes a first diagram 801 illustrating the state of a switch (such as switch 215; see FIG. 2 ). The timing diagram includes a second diagram 803 that illustrates the operating states of a motor (such as the electric motor 103; see FIG. 1 ). Finally, the timing diagram includes a third diagram 805 that illustrates the luminance (luminance) of an associated LED of the rotary tool (such as LED 223; see FIG. 2 ). In the depicted embodiment, the motor of the rotary tool immediately turns on in response to the pressure activation of a switch. If the switch remains pressed over a first time window 809, the LED remains in an "OFF" state 813 until the first time window 809 expires. In the depicted embodiment, the first time window 809 may comprise a predetermined threshold of 1-5 seconds, but other embodiments may comprise other configurations without deviating from the teachings disclosed herein. In the depicted embodiment, the first time window 809 may be 3 seconds, but other embodiments may include other configurations without departing from the teachings disclosed herein. After reaching the first time window 809, the timer is then monitored for an additional time duration at time intervals which correspond to a second time window 811. Once the first time window 809 is reached with the switch held down, the status of the LED changes from the off (OFF) state 813 to the maximum luminance 815. In particular, it should be noted that the state of the motor does not change any further with respect to the continued pressing of the switch, since a different input is required for the deactivation of the motor of the rotary tool.After each time interval following the second time window 811 when the switch is pressed continuously, the luminous state of the LED changes. The illumination changes take place according to a cycle which switches over at regular intervals of the second time window 811. In the depicted embodiment, the LED 5 undergoes lighting states starting at the maximum luminance 815. The further states correspond to changes in illumination of 20% luminance in each case after the expiration of the respectively successive second time windows 811: a second luminance 817 corresponds to 80% of the maximum brightness, a third luminance 819 corresponds to 60% of the maximum brightness, a fourth luminance 821 corresponds to 40% of the maximum brightness, and a fifth luminance 823 corresponds to 20% of the maximum brightness.Other embodiments may offer different luminance cycles, such as 10% steps, 5% steps, or even non-uniform stepwise changes (such as maximum, 80%, 50%, and 10%) without deviating from the teachings disclosed herein. In the depicted embodiment, the second time window 811 may be shorter than the first time window 809, but other embodiments may include other configurations with differing or equivalent time windows without departing from the teachings disclosed herein. In the depicted embodiment, the second time window 811 may include a threshold value up to 1 second, but other embodiments may include other values without deviating from the teachings disclosed herein. Some embodiments may include a second time window 811 in the range of 0.25-5 seconds without deviating from the teachings disclosed herein.Some embodiments may include a cycle with irregular time windows between luminance levels without departing from the teachings disclosed herein. For example, and not limited to, the 80% luminance window associated time window may be shorter than the 20% luminance window without deviating from the teachings disclosed herein.In the depicted embodiment, if the switch continues to be pressed after cycling all available luminance values 815- 823, the next iteration of the cycle returns to maximum luminance 815, but other embodiments may include returning to OFF state 813 or to other values without deviating from the teachings disclosed herein. In the depicted embodiment, the switch is enabled after 5 iterations of the second time window 811, and the setting of the luminance of the LED remains at maximum luminance 815 until another input is received at the switch. In particular, the motor remains operating regardless of the behavior of the LED.FIG. 9 illustrates a timing diagram illustrating the behavior of a rotary tool (such as rotary tool 100; see FIG. 1 ) in accordance with an alternative embodiment of the inventions disclosed herein. The timing diagram includes a first diagram 901 illustrating the state of a switch (such as switch 215; see FIG. 2 ). The timing diagram includes a second diagram 903 illustrating the operating states of a motor (such as the electric motor 103; see FIG. 1 ). Finally, the timing diagram includes a third diagram 905, which illustrates the luminance of an associated LED of the rotary tool (such as LED 223; see FIG. 2 ). In this embodiment, the first time window 809 and the second time window 811 are used as time thresholds similar to the embodiment of FIG. 8, but in contrast different functions of the LED are shown.In the depicted embodiment, the motor of the rotary tool immediately turns on in response to the pressure activation of a switch. If the switch remains pressed over the first time window 809, the LED remains in an "OFF" state 813 until the first time window 809 expires. In the depicted embodiment, the first time window 809 may comprise a predetermined threshold of 1-5 seconds, but other embodiments may comprise other configurations without deviating from the teachings disclosed herein. In the depicted embodiment, the first time window 809 may be 3 seconds, but other embodiments may include other configurations without departing from the teachings disclosed herein. After reaching the first time window 809, the timer is then monitored for an additional time duration at time intervals which correspond to a second time window 811. As soon as the first time window 809 is reached with the switch kept pressed, the status of the LED changes from the OFF state 813 to the first luminance 915, which corresponds to a brightness that has 20% of the maximum luminance. In particular, it should be noted that the state of the motor does not change any further with respect to the continued pressing of the switch, since a different input is required for the deactivation of the motor of the rotary tool.After each time interval following the second time window 811 when the switch is pressed continuously, the luminous state of the LED changes. The illumination changes take place according to a cycle which switches over at regular intervals of the second time window 811. In the depicted embodiment, the LED 5 undergoes lighting states starting at 20% luminance 915. The further states correspond to changes in illumination of 20% luminance in each case after the expiration of the respectively successive second time windows 811: a second luminance 917 corresponds to 40% of the maximum brightness, a third luminance 919 corresponds to 60% of the maximum brightness, a fourth luminance 921 corresponds to 80% of the maximum brightness, and a fifth luminance 923 corresponds to the maximum brightness.Other embodiments may offer different lighting cycles, such as 10% steps, 5% steps, or even non-uniform stepwise changes (such as maximum, 80%, 50%, and 10%) without thereby deviating from the teachings disclosed herein. In the depicted embodiment, the second time window 811 may be shorter than the first time window 809, but other embodiments may include other configurations with differing or equivalent time windows without departing from the teachings disclosed herein. In the depicted embodiment, the second time window 811 may include a threshold of up to 1 second, but other embodiments may include other values without deviating from the teachings disclosed herein. Some embodiments may include a second time window 811 in the range of 0.25-5 seconds without deviating from the teachings disclosed herein.Some embodiments may include a cycle with irregular time windows between luminance levels without departing from the teachings disclosed herein. For example, and not limited to, the 80% luminance window associated time window may be shorter than the 20% luminance window without deviating from the teachings disclosed herein.In the depicted embodiment, if the switch continues to be pressed after cycling all available luminance values 915- 923, the next iteration of the cycle returns to OFF state 813 as the next interval. If the switch remained pressed for a further duration of the second time window 811, the cycle would repeat the iterations, return to the first luminance 915, and process the established cycle as before. Other embodiments may have other values without departing from the teachings disclosed herein. In the depicted embodiment, the switch is enabled after 5 iterations of the second time window 811, and the setting of the luminance of the LED remains in the OFF state 813 until another input is received at the switch. In particular, the motor remains operating regardless of the behavior of the LED.Example embodiments are described above, but it is not to be understood that these embodiments describe all possible forms of the disclosed apparatus and method. The words used herein are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various realized embodiments may be combined to form further embodiments of the disclosed concepts.

Claims

A light emitting circuit for a hand-held tool, the circuit comprising: a first node providing a first input voltage reference; a second node providing a second input voltage reference, the second node being separated from the first node by a capacitor; a third node being separated from the first node by a diode restricting current flow between the first node and the third node and being separated from the second node by a capacitor parallel to a light emitting branch; and wherein the light emission branch comprises: a first sub-branch having a light emitting diode (LED) with a first high pin and a first low pin, a second sub-branch having a transistor arrangement with two second high pins and a second low pin, wherein the transistor arrangement is configured to regulate the current consumption of the light emission branch, wherein the first high pin and one of the two second high pins are connected to the third node and the second low pin is connected to the second node.The light emitting circuit of claim 1, wherein the transistor array comprises a plurality of bipolar transistors (BJTs), wherein the base of a first BJT is electrically connected to the collector of a second BJT, and wherein the base of the second BJT is electrically connected to the emitter of the first BJT.The light emitting circuit of claim 2, wherein the collector of the second BJT is electrically separated from the third node by a first impedance, and the emitter of the first BJT is electrically separated from the second node by a second impedance.The light emitting circuit of claim 3, wherein the first impedance and the second impedance are resistors.The light emitting circuit of claim 2, further comprising a fourth node, wherein the first low pin is electrically connected to the collector of the first BJT.The light emitting circuit of claim 1, wherein the first sub-arm comprises a plurality of LEDs.The light emitting circuit of claim 6, wherein the first sub-arm comprises 4 LEDs.The light emitting circuit of claim 6, wherein the first sub-arm comprises two sub-paths in parallel between the first high pin and the first low pin, each sub-path comprising an LED.The light emitting circuit of claim 8, wherein each sub-path comprises a plurality of LEDs in series.A light emitting circuit for a hand-held tool, the circuit having 4 nodes, a first input voltage reference, a second input voltage reference, a light emitting diode (LED) array, and a transistor array, the circuit further comprising: a first node connected to the first input voltage reference; a second node connected to the second input voltage reference and separated from the first node by a first capacitor; a third node separated from the first node by a zener diode that limits current flow between the first node and the third node, and separated from the second node by a second capacitor and a light emitting branch comprising the LED array and the transistor array, wherein the capacitor and the light emitting branch are parallel; and a fourth node in the light emission branch, the fourth node being separated from the third node by the LED array and being separated from the second node by a sub-path of the transistor array, the transistor array comprising a pair of bipolar transistors (BJTs), wherein the collector of a first BJT is connected to the fourth node, the base of the first BJT is connected to the collector of a second BJT, the emitter of the first BJT is connected to the base of the second BJT and is separated from the second node by a resistor, the collector of the second BJT is separated from the third node by a resistor, and the emitter of the second BJT is connected to the second node.

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