Reference / Paper · 2024
US Patent 12,005,347 B2 — Brown et al., In or Relating to Gaming Controllers (2024)
Sinden's solenoid-recoil patent, read against the D13 regulated recoil stage.
- sinden
- recoil
- solenoid
- gaming controller
Reference / Paper · 2024
Sinden's solenoid-recoil patent, read against the D13 regulated recoil stage.
a2) United States Patent Brown et al. US012005347B2 a0) Patent No.: US 12,005,347 B2 (45) Date of Patent: Jun. 11, 2024 (54) IN OR RELATING TO GAMING CONTROLLERS (71) Applicant: SINDEN TECHNOLOGY LTD, Coventry (GB) (72) Inventors: Garry Brown, Coventry (GB); Andrew James Sinden, Coventry (GB) (73) Assignee: SINDEN TECHNOLOGY LTD, Coventry (GB) (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days. (21) Appl. No.: — 18/258,363 (22) PCT Filed: Dec. 17, 2021 (86) PCT No.: PCT/GB2021/053347 § 371 (¢)(), (2) Date: Jun. 20, 2023 (87) PCT Pub. No.: WO2022/129934 PCT Pub. Date: Jun. 23, 2022 (65) Prior Publication Data US 2023/0398440 Al Dec. 14, 2023 (30) Foreign Application Priority Data Dec. 17, 2020 (GB) wesc cseeeceeseneteeee 2020069 (51) Int. Cl. A63F 13/24 (2014.01) A63F 13/219 (2014.01) (Continued) (52) U.S. Cl. CPC wee A63F 13/245 (2014.09); A63F 13/219 (2014.09); A63F 13/285 (2014.09); (Continued) Bobbin (58) Field of Classification Search CPC .... A63F 13/245; A63F 13/219; A63F 13/285; A63F 13/837; A63F 13/23; HO1F 7/081 See application file for complete search history. (56) References Cited U.S. PATENT DOCUMENTS 6,509,896 BI* 1/2003 Saikawa oi GO6T 19/00 345/419 6,545,661 BI* 4/2003 Goschy ....... A63F 13/211 345/158 (Continued) FOREIGN PATENT DOCUMENTS CN 206342925 U 7/2017 EP 3224125 Al 10/2017 TW 201307791 A 2/2013 OTHER PUBLICATIONS International Search Report and Written Opinion dated Feb. 28, 2022 in corresponding International Application No. PCT/GB2021/ 053347; 10 pages. (Continued) Primary Examiner — Justin L Myhr Assistant Examiner — Carl V Larsen (74) Attorney, Agent, or Firm — Maier & Maier, PLLC (57) ABSTRACT An electronic device for discharging a pulse of current includes an energy storage medium for receiving and storing electric energy supplied from a power source, a solenoid and a control switch connectable with the energy storage medium and the power source and configured to discharge a pulse of current for energising the solenoid when the control switch is activated, whereby the solenoid moves from a first position when the solenoid is not energised, into a second position when the solenoid is energised, and the energised solenoid generates and supplies a current back to the energy storage medium, a processor configured to pro- cess the time taken to energise the solenoid, monitor the (Continued) tet Armature End Cap") Steel Chassis Striker Plate US 12,005,347 B2 Page 2 current drawn by the solenoid from the energy storage medium, and control at least one parameter of a discharged pulse; and an output module to control the discharge of the current from the energy storage medium to the solenoid. 17 Claims, 4 Drawing Sheets (51) Int. Cl. A63F 13/245 (2014.01) A63F 13/285 (2014.01) A63F 13/837 (2014.01) HOI 7/08 (2006.01) A63F 13/23 (2014.01) (52) U.S. CL CPC wee A63F 13/837 (2014.09); HOLF 7/081 (2013.01); A63F 13/23 (2014.09) (56) References Cited U.S. PATENT DOCUMENTS 9,810,502 B2* 11/2017 Monti oe F41A 33/06 10,852,093 B2* 12/2020 Monti ... . A63F 13/837 11,194,396 B1* 12/2021 Wang .... ... GO6F 3/016 11,314,339 B2* 4/2022 Sinden .. .. A63F 13/426 2003/0155444 A1* 8/2003 Lawes oo... F02M 51/04 239/585.1 2007/0117628 Al* 5/2007 Stanley ..........0... A63F 13/212 463/36 2010/0167820 Al* 7/2010 Barakat .......0..0... A63F 13/212 463/40 2012/0302348 Al* 11/2012 Karacal «0.0.0.0... A63F 13/837 463/38 2014/0287806 Al* 9/2014 Balachandreswaran ...........c8 A63F 13/428 463/7 2016/0018185 Al* 1/2016 Makohon ............... F41C 27/00 42/90 2016/0292924 Al* 10/2016 Balachandreswaran uu... GO6F 3/012 2019/0278369 AL* 9/2019 Ballard oo... A63F 13/285 2019/0351297 A1* 11/2019 Wolfe... A63B 71/0619 2020/0064922 AL* 2/2020 Nocon oo... GO6F 3/016 2021/0164751 AL* 6/2021 Monti on. F41A 33/06 2022/0387724 A1* 12/2022 Helmer ............. A61M 5/31578 OTHER PUBLICATIONS Search Report dated Jun. 2, 2021, in corresponding British Appli- cation No. GB2020069.7, 2 pages. Examination Report dated Jul. 13, 2021, in corresponding British Application No. GB2020069.7, 2 pages. Sinden Technology., “The Sinden Lightgun”, Kickstarter.com, 2021, 12 pages. Notification of Grant dated Apr. 18, 2023, in corresponding British Application No. GB2020069.7, 2 pages. Sinden Technology, “First look at Sinden lightgun Recoil unit!”, https://www.youtube.com/watch?v=YZxbNMy 114M; 1 page. * cited by examiner U.S. Patent Jun. 11, 2024 Sheet 1 of 4 US 12,005,347 B2 16 42 24 20 6 Figure 4 First Trough during guise i i i } i } } Seat DE Palse } } } } } } Figure 2 U.S. Patent Jun. 11, 2024 Sheet 2 of 4 US 12,005,347 B2 LISEAR URAL RESDLATION DEVICE VOLTAGE, A “TEssrER SISTEM. CONTEDL UPRENT MEAHMEMERT Figure 3 Bobbin Armature Steel Chassis Cail Figure 4 U.S. Patent Jun. 11, 2024 Sheet 3 of 4 US 12,005,347 B2 Bobbin Armature Steel Chassis Striker Plate Figure 5 Magnetic Path Figure 6 “SOLENOID_POS_ TERMINAL » SE COW “R Solenoid - Coil Resistance ‘Y APPLIED VOLTAGE ps ’ Induced Voltage “SOLENOID_NEG TERMINAL - Figure 7 U.S. Patent Jun. 11, 2024 Sheet 4 of 4 US 12,005,347 B2 Current {A} Figure 9 US 12,005,347 B2 1 IN OR RELATING TO GAMING CONTROLLERS FIELD The present invention relates to a gaming controller for use in computer games played on modern displays and, in particular, a gaming controller provided with a recoil fea- ture. A gaming controller is a physical device used to control a computer game or computer simulator. As such, a gaming controller includes, but is not limited to lightguns, game- pads, driving steering wheels, flight yokes, virtual pinball buttons and joysticks. BACKGROUND Lightguns are gaming or simulator controllers where a user points a controller device at a display and shoots or otherwise interacts with targets displayed on the screen. Solenoids are used in many applications such as haptic feedback in video games, pinball machines, opening elec- tronic locks, controlling valves on sprinkler systems and many more. It is common to drive these solenoids directly from an available power supply. However, the issues with current solenoid integration in existing devices are that they require a very powerful power supply to provide enough current to directly energise the solenoid which is expensive and inefficient. Additionally in this type of integration the solenoid generates a lot of heat which interferes with the functionality and creates more wear and tear on the solenoid so it can break sooner. Therefore, there is a requirement to provide a device comprising an advanced circuit to control and monitor a solenoid in order to give more flexibility in controlling the solenoid as well as reducing power supply requirements, reducing heat, removing the requirement for additional sensors (such as a temperature sensor) and increase the usable lifetime of a solenoid. SUMMARY It is against this background that the present invention has arisen. In an aspect of the present invention, there is provided an electronic device for discharging a pulse of current, the device comprising an energy storage medium for receiving and storing electric energy supplied from a power source, a solenoid and a control switch connectable in series with the energy storage medium and the power source, the energy storage medium is configured to discharge a pulse of current for energising the solenoid when the control switch is activated, whereby the solenoid moves from a first position in which the solenoid is not energised, into a second position in which the solenoid is energised, wherein the energised solenoid is able to generate and supply a current back to the energy storage medium, a circuitry unit comprising a processor configured to process the time taken to energise the solenoid; wherein the processor is further configured to monitor the current drawn by the solenoid from the energy storage medium; wherein the processor is further configured to control at least one parameter of a discharged pulse; and an output module associated with the processor, wherein the output module is configured to be operable by an 10 15 20 25 30 35 40 45 50 55 60 65 2 operator to control the discharge of the current from the energy storage medium to the solenoid. In some embodiments, the energy storage medium can be a capacitor. There are several advantageous to the present invention as disclosed herein. The present invention can be used for driving the solenoid from the energy storage medium instead of directly from the power supply. This provides an advan- tage that the energy of the pulse can be greater than the energy a power source or supply can provide in the same amount of time. Therefore, this can drive a more powerful solenoid from the same power supply or use a smaller power supply for the same strength solenoid. A smaller power supply provides a cost saving in manufacturing cost and uses less power such as electricity during normal use, which saves money and can be environmental friendly. In another advantage, the processor of device of the present invention can be used for monitoring the current drawn by the solenoid and it can be possible for the processor to obtain or record a dataset. The processor can be further configured to use the information obtained during the monitoring phase to control the duration and strength of the pulse. In some embodiments, the processor can be a microcon- troller. In some embodiments, the device comprising an advanced circuit can be used to monitor the current that is drawn by the solenoid as it is firing. In some embodiments the current measurement device is realised by placing a small resistor in the path of the current. A microcontroller (or other voltage measuring device) can then be used to measure the voltage across the resistor. In a standard use of a solenoid, for example providing haptic feedback in an arcade video game system, the sole- noid can be powered directly from the available power supply. The power supply feed to the solenoid can be controlled by a basic electronic circuit that can use a transistor to switch the power on and off to the solenoid. As the user plays the video game and performs an action that requires haptic feedback such as pulling a trigger on a gun shaped computer games controller, the games software can send an electronic signal to the device to provide an output such as toggling the transistor and allowing the power to go through to the solenoid. Typically, this can fire for a pre-determined pulse dura- tion. The firing of the solenoid and a plunger (the centre bolt of the solenoid) can be pulled into the centre of the solenoid. This action movement and impact provides a recoil effect to the user. When that pulse is complete the plunger can then be returned to its original position using a spring. In some embodiments, at least one parameter of the discharged pulse comprises duration, voltage or current. In some embodiments, the power source is a USB port. In some embodiments the device includes a means for increasing or decreasing the voltage available from the power source, for the purposes of being able to set the voltage that is most efficient to power the solenoid. In some embodiments, the electronic device may further comprise a de-surging means configured to prevent a current surge from being drawn from the power source. In some embodiments, the de-surging means is an inrush control circuit. Providing an inrush control circuit can be advantageous because it can be used to stop a user from blowing the power source for example by taking too much current from USB Moreover, the inrush control circuit may also be used to stop pushing energy back to power source (usb). For US 12,005,347 B2 3 example, a switch can be provided that passes runs the input current through a resistor until the circuit is ready and will therefore not draw excessive current. In some embodiments, the electronic device may further comprise a decoupling capacitor configured to prevent excessive ripple in the current drawn from the power source and/or to prevent the voltage supply the remainder of the circuitry from dipping in the event that surges of current are drawn by said circuitry. The decoupling capacitor can also be used for smoothing the input current, reducing pulsating effect. In some embodiments, the electronic device may further comprising a decoupling capacitor configured to prevent excessive ripple in the current drawn from the power source and/or to prevent damage to the power supply in the event that surges of current are drawn by the electronic device. In some embodiments, a capacitor may be provided including a pre-charge circuit to charge the decoupling capacitor with a limited current and a switch to connect it to the supply once charged. In some embodiments, the decoupling capacitor can be charged with the circuit as disclosed herein and it can stop a current spike when first connected to a power supply. In some embodiments, the electronic device may further comprise an interruption means configured to interrupt the current drawn from the power source. The interruption means can be a transistor. Preferably the interruption means takes the form of a switching device in series with the supply current. A transistor can be used to disconnect the electronic device from the power source. In some embodiments, the device has a means of inter- rupting the current incoming to the device to provide a means of preventing a current surge on initial connection. In some embodiments, the means of interrupting the current provides a means of preventing the remainder of the circuitry from operating prior to the decoupling capacitor being switched into the circuit. In some embodiments, the means of interrupting the current provides a means of placing the circuit into a non-operational state drawing minimal current from the power source. In some embodiments, there is provided a means of series regulation of current flow from the preceding circuitry into the energy storage device. This can be advantageous as it blocks the current to energy storage medium until circuit in the device hits the minimum required voltage. In some embodiments, there is provided a means of controlling the voltage supplied to the energy storage device. This allows us to control the amount of energy stored. In some embodiments, a control switch exists to control the flow of current from the energy storage module to the load solenoid in order to control the current to energize the solenoid. In some embodiments a transistor may be used as a control switch. In some embodiments, the control switch is further con- figured to route the power from the solenoid into the energy storage medium. This is advantageous because it enable the recovery of energy from the solenoid at the end of the pulse or period of operation. This is used where the solenoid is a device which (*directly or indirectly) stores energy and can return that energy, a solenoid stores energy in 2 places, in its inductance (coils as magnetic field) and as mechanical potential (such as returning spring). In some embodiments, the magnitude of current flow in the solenoid can be regulated. This current control may be achieved by modulating the applied voltage applied to the solenoid coil. Preferably this modulation would involve 10 15 20 25 30 35 40 45 50 55 60 65 4 either applying nominally zero voltage across the solenoid coil for a period or reconfiguring the power switches so as to return a portion of the stored energy from the solenoid to the storage means. These methods minimize wasted energy and heat dissipation during the regulation of current. In some embodiments, there is provided a means of disconnecting the load from the energy source but providing a current path with minimal voltage drop across the load terminals. Preferably the means comprises electronic switches configured to route current from the solenoid to the energy storage device in such a direction as to charge the energy storage device. In some embodiments these elec- tronic switches may be diodes or transistors. Preferably the operation of these electronic switching devices is controlled directly or indirectly by the processor. By cycling between load disconnection as described here, and connection of the load to the energy storage, the magnitude of current flow in the solenoid can be regulated. In some embodiments, the processor is further configured to measure the current flow through the solenoid or a solenoid switch. In some embodiments, the electronic device may further comprise a resistor in series with the solenoid coil. By measuring the voltage drop across this resistor, the magni- tude and direction of the current flowing in the solenoid coil can be determined. In some embodiments the measurement may be carried out by an analogue to digital converter, which may be integrated into a microcontroller. There is a means provided for setting the maximum level of current drawing from the power source. The level of current drawn from the power source can be controlled be varying a parameter of the de-surging circuit or the means for increasing or reducing the voltage applied to the energy storage means, or by a combination of these methods. An example of such a control method would be varying the duty ratio of a switch mode regulator used to vary the voltage applied to the energy storage means. In some embodiments, there is provided a system for controlling the circuitry, which can be connected to a master control system, which can issue commands which may control some or all of the following: output pulse duration, output voltage, output current, maximum current drawn from the power source. In some embodiments, either, or both, of the discharged (output) pulse duration and output pulse current can be varied by an algorithm based on output voltage, output current, timing or any combination thereof in order to provide the optimum output pulse to achieve a given requirement. Solenoid performance data can be measured and stored by the device and then transmitted to the application that uses the solenoid so that it can calculate optimum settings for maximum performance. In some embodiments, the device may further comprise a temperature sensor positioned within the solenoid, wherein the temperature sensor is configured to detect a temperature value of the solenoid and transmit the detected temperature value to the processor. The data obtained can be calculated by the circuit to give more accurate results. In some embodiments, the use of device may further provide a method for measuring the current drawn by the solenoid against time and compare this performance data with known measurements of the solenoid and circuit at different temperatures. Therefore, compare to this data and able to provide an accurate calculated estimate of the sole- noid temperature. US 12,005,347 B2 5 In some embodiments, machine learning can be deployed for all the measured parameters to calculate the most effi- cient settings such as pulse duration, solenoid voltage and solenoid current. An example implementation could be while the solenoid is being used with default settings for parameters the machine learning algorithm can collect per- formance data such as how long the armature in the solenoid takes to impact the maximum and the shape of the current against time graph, the algorithm can then adjust the avail- able parameters in small increments higher and lower in different combinations and again measure the performance. It can then analyse the performance data of the solenoid to decide the optimum parameter settings. It can then continue to adjust the parameters throughout usage and measure the performance and continue to set optimum values. This way if the environment changes for example temperature or the energy storage medium performance fluctuating then the device can continue to calculate the best parameter settings and run at the optimum settings. When using a reduced duration pulse of energy to the solenoid, after the pulse is completed, if the circuit still provides some electricity to the solenoid (but a smaller amount), this will allow it to be able to measure the changing current and calculate when or if the solenoid has reached its maximum. This measurement is used in other calculations to optimise performance. The electronic device can also be used to monitor the energy stored in the energy storage medium to use this data in other calculations by the circuit. For example, if a user wants to provide a 10 ms duration high energy pulse to the solenoid but it is known there is not enough energy in the energy storage medium then the algorithm, the user can decide what course of action best suits the use of the circuit or example if opening a door lock with a solenoid, then there is no point firing the solenoid as the door won’t open, so it can be better to wait until there is enough energy, but in a recoil solenoid usage, a user might as well fire but have a reduced strength haptic feedback because the user can’t wait till more energy has built up as it will be out of sync. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further and more particularly described, by way of example only, and with reference to the accompanying drawings, in which: FIG. 1 shows the electronic device according to the present invention; FIG. 2 shows a typical solenoid current against time graph FIG. 3 show an advanced circuit according to the present invention; FIG. 4 provides a cross Section of a solenoid; FIG. 5 shows an illustration of a solenoid in a Lightgun application; FIG. 6 shows a magnetic Path in the Solenoid; FIG. 7 shows a solenoid circuit; FIG. 8 shows a solenoid current waveform; and FIG. 9 shows a current waveform processing and param- eters. DETAILED DESCRIPTION OF THE EMBODIMENTS Referring to FIG. 1, there is shown an electronic device 10. The electronic device may comprise a circuit 12 for processing, controlling, monitoring a current between a power source (not shown in the accompanying figure) and a solenoid 14. An energy storage medium such as a capacitor 10 15 20 25 30 35 40 45 50 55 60 65 6 16 is provided for receiving and storing electric energy supplied from a power source. The solenoid 14 can be connected to a control switch, which can be connectable in series with the energy storage medium 16 and the power source, the energy storage medium 16 is configured to discharge a pulse of current for energising the solenoid 14 when the control switch is activated, whereby the solenoid 14 moves from a first position in which the solenoid 14 is not energised, into a second position in which the solenoid 14 is energised, wherein the energised solenoid 14 is able to generate and supply a current back to the energy storage medium 16. A circuitry unit comprising a processor 18 i.e. the advanced solenoid control circuit shown in FIG. 1 is con- figured to process the time taken to energise the solenoid 14; where the processor 18 is further configured to monitor the current drawn by the solenoid 14 from the energy storage medium 16. The processor 18 is further configured to control at least one parameter of a discharged pulse and an output module, such as a trigger 20 as shown in FIG. 1, is associated with the processor 18, where the output module 20 is configured to be operable by an operator to control the discharge of the current from the energy storage medium 16 to the solenoid 14. Referring to FIG. 1, there is also shown a computer games lightgun that connects to a computer using a USB interface. It shows a recoil mechanism as described in this patent. The main features include: A solenoid which when energised provides a desired recoil effect, this includes: A solenoid coil 28 which becomes an electromagnet when energised and a armature/ plunger 28 which is the part of the solenoid mechanism that physically moves when attracted by the solenoid coil. FIG. 1 shows a capacitor that acts as the energy storage medium; a physical trigger which provides the event to action the recoil event; an impact plate 22 for the solenoid armature to impact with when the return spring pulls the armature back; a USB cable 24 to connect to the computer which pro- vides communication and the energy source for the circuit; an advanced solenoid control circuit 18 hereby also known as an SCC; a main lightgun board 12 which provides the lightgun functionality; and a cable 26 to send communication between the main lightgun board that provides lightgun functionality and the solenoid control circuit (SCC). A computer games lightgun with recoil effect solenoid, configured to provide a pulse duration long enough to last until the plunger has hit the maximum. To provide maximum haptic feedback, a large solenoid is used that in normal usage would require too much current and energy to be used via a USB power source. With the advanced solenoid circuit this large solenoid is able to be used and provide super perfor- mance including haptic feedback. A Lightgun is connected to the computer via a USB cable which also provides the power (5V and a maximum of 500 mA). The advanced solenoid circuit initiates Inrush control circuit prevents the device from drawing excessive current at the moment of connection to the USB port. A decoupling capacitor provides a low impedance source to supply short term current peaks drawn by the downstream circuitry. It then recharges when current demand falls, thus reducing ripple in the current draw from the source. US 12,005,347 B2 7 The decoupling capacitor is initially charged by a limited current, thereby preventing a current spike from being drawn. At the same time, the energy storage capacitor is pre-charged. While the capacitors are being pre-charged, the micro- controller performs initialization routines and configures control signals to the hardware, ready to begin operation. Once the decoupling capacitor has reached a suitable level of charge and the initialization is complete, the microcon- troller enables the power input circuitry. At this point, a switch connects the decoupling capacitor to the supply rail via a low resistance path. The enabling of the power circuit also causes another switch to route power to the voltage boost circuit. The current it can draw is limited to 350 mA. This is because the rest of the lightgun needs current also and it is important not to exceed the 500 mA limit of the USB power source. The user starts playing a game which has recoil effect enabled. User pulls the trigger which activates a switch which is read by the main lightgun board. Therefore the solenoid needs to fire to provide haptic feedback. The lightgun board sends a “fire” solenoid signal over a cable to the solenoid control circuit. The solenoid control circuit uses a transistor to route power from the capacitor to the solenoid. The solenoid plunger starts moving towards the centre of the coil. The solenoid control circuit from here on known as the SCC, measures the current drawn from the solenoid. It looks for a low point in the current drawn which represents the trough shown on FIG. 1. This means the solenoid plunger has reached its maximum. It then ends the pulse. This saves energy and prevents the solenoid from over- heating. The Inductance in the solenoid coil now converts to electricity which is routed by the SCC back into the capaci- tor to recover as much of the energy as it can. Additionally the moving plunger being pushed back into its starting position by the return spring moving through the magnetic field in the coil also creates electricity which is routed into the capacitor. The capacitor continues charging from the USB power during these events. The user pulls the trigger again, very quickly after the last time. As the capacitor was provided with the retrieved energy from the solenoid and it has also has a small amount of time in between firing to charge, it now has enough energy to do another pulse and fire the solenoid and the plunger reach the maximum and provide good haptic feed- back. If the SCC was not used, then there would not be enough energy to fire the solenoid so quickly again and a smaller strength solenoid would need to be used (so worse haptic feedback performance), or an external power supply pro- vided (more cost and less convenient). Additionally if the SCC was not used and an external power supply was used then there would be more heat generated due to less efficient pulses which means the solenoid would need to be deactivated when it got too hot. Which stops the haptic feedback working. A temperature sensor would need to be added to the solenoid. The extra heat would mean the solenoid was more likely to fail quicker. The device comprising an advanced circuit as disclosed herein in the present invention aims to improve the scenario described above in the following ways: 10 15 20 25 30 35 40 45 50 55 60 65 8 Driving the Solenoid from an Energy Storage Medium Instead of Directly from the Power Supply This is a known solution in electronics to use an energy storage medium such as a capacitor or a battery to charge from the power supply. Then when required use this stored energy in a pulse to activate a solenoid. This provides an advantage that the energy of the pulse can be greater than the energy a power supply can provide in the same amount of time. Therefore, this drives a more powerful solenoid from the same power supply or use a smaller power supply for the same strength solenoid. A smaller power supply provides a cost saving in manufacturing cost and will use less electric- ity in normal use which saves money and is good for the environment. Referring to FIG. 2, there is shown a graph illustrating the monitoring of the current drawn by the solenoid by the processor. From the information obtained through monitor- ing of the current, the processor can be further configured to control the duration and strength of the pulse. The advanced circuit as disclosed herein is able to moni- tor the current that is drawn by the solenoid as it is firing. A small resistor can be provided within the circuit on the path the electricity is supplied. The processor, such as a micro- controller or other voltage measuring device, can provide to measure the voltage across the resistor. Using the electronics formula: Voltage=CurrentxResistance As the resistance is a known value, when the voltage is measured and then deduce the current. A firing solenoid draws a different amount of current during its action as shown by FIG. 2 a typical solenoid current against time graph. Referring to FIG. 2, the end result is that by monitoring the current drawn, the user can work out where in the cycle the solenoid plunger is. The first peak will normally be at the point of maximum acceleration and the first trough is actually where the plunger has reached the end of its journey. A normal solenoid circuit will use a set pulse and as shown on the graph, the solenoid still uses significant amounts of current after it has reached its maximum. This wastes energy and generates heat which long term causes more wear and tear on the solenoid. The advanced circuit therefore monitors the current and looks for the trough in FIG. 2. After calculating the trough point has occurred then the circuit ends the pulse. This means the circuit is not wasting energy by supplying sig- nificant energy after the solenoid has reached its maximum. This reduces the energy required per pulse, reduces the waste heat generated and also increase the life of the solenoid. By using less energy it means with a limited amount of energy available you can fire more full strength solenoid actions in the same amount of time. Monitoring the Current to Create an Even More Efficient Pulse The last section described the most efficient way to do a full strength pulse. However there is still an opportunity to do an even more efficient lower energy pulse and still have the plunger reach its maximum within the solenoid. If you stop the pulse before the plunger has the maximum there is still a certain length of pulse where the plunger has enough momentum to still hit the maximum. This innovation uses the monitored solenoid current to calculate the point where the pulse can end early but still achieve its aim of reaching the maximum. As the simplest implementation, the circuit can perform a calibration process to work out the optimum pulse. It can fire US 12,005,347 B2 9 a normal pulse and measure where the trough as shown on the FIG. 1 graph occurs. This is the starting duration of the pulse. It can then reduce the time of the pulse to see whether the plunger still reaches the maximum. So for example on the example showed on the FIG. 1 graph the duration of pulse was 14 ms for the plunger to hit maximum. A good first estimate for an optimum duration value is on the first peak as shown in FIG. 1. This occurs after 8 ms. So the calibration routine can then try 8 ms as a pulse. After 8 ms it reduces the current or voltage on the pulse to a much smaller value. This is because some current still needs to flow to be able to measure when the plunger has reached the maximum (by measuring the trough point as shown on FIG. 1). If the trough event occurs in the measured data then the circuit knows the plunger reached the maximum, the circuit can then slowly decrease the pulse to work out the most efficient pulse duration to reach maximum. If the trough event doesn’t occur then it can slowly increase the pulse duration to work out the optimum point. In normal use when you find the optimum point you would most likely add a bit more time to the pulse to ensure there is room for error and that it still reaches the maximum. This value can change through use with changes in temperature and other factors that can affect electrical circuit performance. So in this simple circuit you need to keep monitoring that it reaches the maximum or you need to increase the pulse duration. A more advanced circuit can decide how long the pulse duration should be after it has reached the first current peak as shown on FIG. 1. This way when factors such as temperature change the peak on the graph will move posi- tion. Therefore because the pulse is set to last a duration after the peak, the circuit will dynamically adjust during use based on changing factors such as temperature. A very advanced version of the circuit could use machine learning and calculate the optimum pulse by measuring all the data values and learning what values result in a success- ful plunger reaching maximum event. It would continually measure the variables during operation to maintain the optimum pulse length. In the example first provided describing haptic feedback in an arcade video game system you don’t just want the plunger to make the maximum but also want it to hit the maximum with a good enough force to provide good haptic feedback. So in the algorithms described above you would likely add a set duration of pulse on top of your optimum pulse to make sure it hits with the required force. Where as in a scenario where you just need the solenoid plunger to reach the maximum then you don’t need to add on an additional length pulse. You can see as shown on FIG. 1 that if you were able to reduce the pulse starting from the first peak at 8 ms pulse duration instead of 14 ms which is when the maximum is reached, then the pulse only needs to last 57% as long which is a substantial energy saving. Recovering Energy after a Solenoid Plunger has Reached the Maximum At the point the solenoid plunger has reached the maxi- mum it has actually built up substantial energy in the solenoid. If this energy could be recovered then if the solenoid is using a power source with a limited amount of energy then it would be able to action the solenoid again with a smaller wait time in between. The solenoid has stored up energy in the inductance stored in the coil and also mechanical energy as the plunger has a return spring that will return it back to the starting position. 15 35 40 45 60 65 10 The advanced circuit is designed to route energy from both these sources back into the energy storage medium. As the inductance reduces it naturally converts into elec- tricity back into the circuit. By changing the path the energy travels in the circuit this energy is switched to travel back into the capacitor. As the plunger is returned back to its started position by the return spring it travels though the magnetised solenoid coil. This is the opposite of what it did when it was first activated and therefore it converts the magnetic energy to electrical energy instead. This electrical energy is also routed to travel back into the capacitor. By recovering energy from both of these sources it means the overall energy used during a pulse is less and therefore you can fire the solenoid with a shorter duration of waiting in between. Measuring the Temperature of a Solenoid without a Temperature Sensor It is very common for solenoids to be used in a system in a circuit with a temperature sensor to measure the tempera- ture of the solenoid. This is so the circuit can shut off solenoid functionality if the solenoid is over-heating. Too much heat can damage a solenoid and reduce its lifetime. The pattern of current against time during the action of a solenoid follows a set pattern with a known curve, however the exact parameters of the curve change against tempera- ture when all other variables are consistent. For a solenoid these can be measured against different temperatures. Then when measuring these parameters against known parameters it is possible to deduce what the temperature of the solenoid is. Therefore a temperature sensor is not required to be added to the circuit which is a cost saving. If there any other variables that might affect the param- eters other than temperature then it is possible to measure these also to remove their effect from the calculation. So for example a capacitor gets less effective over time. So if you measure the voltage across the fully charged capacitor you will be able to measure if it has reduced performance and you can use that measurement of reduced performance as a variable in your temperature calculation to get a more accurate result. EXAMPLES In computer game hardware solenoids are commonly used to provide haptic feedback to the user. The most common standard for computer games controllers such as gamepads and lightguns use a USB connection. A typical USB2 connection which is a very common standard supplies 0.5 mA of current per port. A typical solenoid that can action under that current would be very small and only supply minimal haptic feedback to the user. If the solenoid was for example trying to make the user of a lightgun feel like they were firing a real gun a small non-powerful solenoid will not give this feeling. So there is a need to use a much more powerful solenoid that has a current requirement higher than the available current on USB2. It is possible to use an external power supply but this adds cost and also additional wiring which is not desirable. It is possible to use the configuration described in the description where an energy storage medium is used to build up the energy to fire the solenoid. In this example a capacitor is used. However even with this configuration there will be a solenoid that requires too much energy and will take too long in between actions for the capacitor to charge in time for the next action. US 12,005,347 B2 11 Using the technology as described in this patent a more powerful solenoid can be used than otherwise would be possible. This is beca