System and method for reducing afterglow effect of light emitting diodes

Abstract

The present disclosure provides a system comprising: a light emitting diode (LED); a switching circuit configured to: when in a first state, connect an anode of the LED to a positive potential and a cathode of the LED to a ground potential, thereby enabling current to flow through the LED in a first direction; and when in a second state, perform one of: connecting the ground potential to the anode of the LED; connecting a negative potential to the anode of the LED; and connecting the cathode of the LED to the positive potential and the anode of the LED to the ground potential, thereby enabling current to flow through the LED in a second direction, wherein the second direction is opposite to the first direction; and a driver module configured to selectively transition the switching circuit from the first state to the second state and from the second state to the first state.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 16 / 919,200, filed July 2, 2020. The entire disclosure of the above application is incorporated herein by reference. Technical Field

[0003] This disclosure relates to light-emitting diodes (LEDs), and more specifically to systems and methods for reducing the afterglow effect of LEDs. Background Technology

[0004] The information provided in this section is intended to provide a general overview of the background of this disclosure. The work of the currently named inventors (to the extent described in this section) and aspects of the specification that may not otherwise be prior art at the time of filing are neither expressly nor implicitly acknowledged as prior art to this disclosure.

[0005] This disclosure relates to light-emitting diodes (LEDs), and more specifically to systems and methods for reducing the afterglow effect of LEDs.

[0006] A light-emitting diode (LED) is a semiconductor-based light source. When an electric current flows through an LED, it emits light. Electrons and electron holes in the semiconductor recombine to release energy in the form of photons. The color of the light emitted by an LED corresponds to the energy of the photons.

[0007] LEDs are used in a wide variety of industries. For example, some LEDs emit low-intensity infrared (IR) light and are used in remote control circuits, such as for controlling televisions. As another example, LEDs can be used as visual indicators and in place of light bulbs. LEDs can also be used as other light sources, such as in residential and commercial lighting. As yet another example, LEDs can be used in seven-segment displays and other types of displays. LEDs have advantages over incandescent light sources (e.g., light bulbs), such as lower energy consumption, lower heat generation, and longer lifespan. Summary of the Invention

[0008] In one feature, a system includes: a light-emitting diode (LED) having an anode and a cathode; a switching circuit configured to: when in a first state, connect the anode of the LED to a positive reference potential and connect the cathode of the LED to a ground reference potential, thereby enabling current to flow through the LED in a first direction; and when in a second state, perform one of the following operations: connect the ground reference potential to the anode of the LED; connect a negative reference potential to the anode of the LED; and connect the cathode of the LED to a positive reference potential and connect the anode of the LED to a ground reference potential, thereby enabling current to flow through the LED in a second direction, wherein the second direction is opposite to the first direction; and a driver module configured to selectively switch the switching circuit from the first state to the second state and from the second state to the first state.

[0009] In a further feature, when in the second state, the switching circuit is configured to connect a ground reference potential to the anode of the LED.

[0010] In a further feature: the switching circuit includes: a first switch having a first terminal connected to a positive reference potential and a second terminal connected to a first node; a second switch having a first terminal connected to the first node and a second terminal connected to a second node; an anode of an LED connected to the first node; a cathode of an LED connected to the second node; and a ground reference potential connected to the second node.

[0011] In a further feature, the driver module is configured to: close the first switch and open the second switch to operate the switch circuit in a first state; and open the first switch and close the second switch to operate the switch circuit in a second state.

[0012] In a further feature, when in the second state, the switching circuit is configured to connect a negative reference potential to the anode of the LED.

[0013] In a further feature: the switching circuit includes: a first switch having a first terminal connected to a positive reference potential and a second terminal connected to a first node; a second switch having a first terminal connected to a negative reference potential and a second terminal connected to the first node; and a second node connected to the cathode of the LED; and the anode of the LED connected to the first node.

[0014] In a further feature, the driver module is configured to: operate the switching circuit in a first state by closing the first switch and opening the second switch; and operate the switching circuit in a second state by opening the first switch and closing the second switch.

[0015] In a further feature, the driver module is configured to: keep the first switch open and the second switch closed for a predetermined afterglow period; and once the predetermined afterglow period has passed, open the second switch.

[0016] In a further feature, when in the second state, the switching circuit is configured to connect the cathode of the LED to a positive reference potential and the anode of the LED to a ground reference potential, thereby allowing current to flow through the LED in the second direction.

[0017] In a further feature: the switching circuit includes: a first switch having a first terminal connected to a positive reference potential and a second terminal connected to a first node; a second switch having a first terminal connected to a positive reference potential and a second terminal connected to a second node; a third switch having a first terminal connected to the first node and a second terminal connected to a ground reference potential; and a fourth switch having a first terminal connected to the second node and a second terminal connected to a ground reference potential; the anode of the LED is connected to the first node; and the cathode of the LED is connected to the second node.

[0018] In a further feature, the driver module is configured to operate the switching circuit in a first state by closing the first and fourth switches and opening the second and third switches; and to operate the switching circuit in a second state by opening the first and fourth switches and closing the second and third switches.

[0019] In a further feature, the driver module is configured to: keep the first and fourth switches open and the second and third switches closed for a predetermined afterglow period; and once the predetermined afterglow period has passed, disconnect the second and third switches.

[0020] In a further feature, the driver module is further configured to close the fourth switch once the predetermined afterglow period has passed.

[0021] In a further feature, the LED is configured to emit light with wavelengths between 700 nanometers (nm) and 1 millimeter (mm).

[0022] In further features: a camera; and an imaging module configured to: actuate the camera and capture a first image using the camera when the switching circuit is in a first state; and actuate the camera and capture a second image using the camera when the switching circuit is in a second state.

[0023] In a further feature, the imaging module is configured to actuate a camera and capture images at a predetermined frequency, wherein the predetermined frequency is at least 10 Hz.

[0024] In a further feature, the driver module is configured to switch the switching circuit from a second state to a first state at a predetermined frequency.

[0025] In a further feature, the imaging module is configured to adjust the first image using the second image.

[0026] In a further feature, the camera is an infrared (IR) camera and is configured to capture images of the passenger compartment of the vehicle.

[0027] In one feature, a method includes: selectively operating a switching circuit in a first state such that: the anode of a light-emitting diode (LED) is connected to a positive reference potential; the cathode of the LED is connected to a ground reference potential; and current is allowed to flow through the LED in a first direction; and selectively operating the switching circuit in a second state such that: the ground reference potential is connected to the anode of the LED; a negative reference potential is connected to the anode of the LED; the cathode of the LED is connected to a positive reference potential, the anode of the LED is connected to a ground reference potential, and current is allowed to flow through the LED in a second direction, wherein the second direction is opposite to the first direction; and selectively switching the switching circuit from the first state to the second state and from the second state to the first state.

[0028] Further areas of applicability of this disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0029] This disclosure will be more fully understood in light of the specific embodiments and accompanying drawings, wherein:

[0030] Figure 1 This is a functional block diagram of an exemplary vehicle system;

[0031] Figures 2 to 4 This is a schematic diagram of an exemplary circuit for minimizing the afterglow of a light-emitting diode; and

[0032] Figure 5 This is a flowchart depicting an exemplary method for turning on and off a light-emitting diode (LED) while minimizing its afterglow.

[0033] In the accompanying drawings, reference numerals may be used repeatedly to identify similar and / or identical elements. Detailed Implementation

[0034] Light-emitting diodes (LEDs) can be used for lighting, such as in the passenger compartment of a vehicle. When a camera is used, the LEDs can be turned on, illuminating the environment in an image captured by the camera. This type of image can be called a content image. Background images can also be captured with the LEDs off. Characteristics of the background image (e.g., background lighting) can be used to adjust the characteristics of the content image.

[0035] Even after the current flowing through an LED is stopped, the LED will continue to emit light for a period of time. This phenomenon is known as LED afterglow. LED afterglow can affect one or more characteristics of the background image. The background image (captured during the afterglow period) can influence the adjustment of the content image.

[0036] This application relates to minimizing LED afterglow. For example, an LED driver module can shunt the LED anode to ground to minimize the LED afterglow (duration). As another example, the driver module can apply a negative reference potential to the LED anode or apply power to the LED in the opposite direction to its normal orientation to minimize the LED afterglow (duration). This can improve the background image.

[0037] Figure 1 A functional block diagram of an exemplary vehicle 100 is included. While a vehicle example is provided, this application is also applicable to non-vehicle-specific implementations including LEDs (e.g., machine vision, optical inspection, lighting) and other uses of LEDs in vehicles.

[0038] Vehicle 100 includes a passenger compartment comprising one or more seats, such as seat 104. When the vehicle is in motion, vehicle occupants can sit in the seats within the passenger compartment. Vehicle 100 can be an autonomous vehicle (driving without user input), a semi-autonomous vehicle (driving without user input in some situations and based on user input in others), or a non-autonomous vehicle (driving by a user). While an example of two seats is provided, vehicle 100 may include more than two seats or only one seat. Seatbelts are provided in each seat.

[0039] Camera 108 is configured and arranged to capture images inside the crew compartment. Camera 108 may be, for example, an infrared (IR) camera or another suitable type of camera.

[0040] Imaging module 112 triggers camera 108 to capture images at a predetermined frequency (such as 20 Hz to 110 Hz or another suitable frequency). Thus, camera 108 captures one image at predetermined time intervals, where the predetermined time interval corresponds to 1 divided by the predetermined frequency. Images alternate between content images and background images. In other words, one image captured by camera 108 is a content image, the next image captured by camera 108 is a background image, the image after that is a content image, the image after that is a background image, and so on.

[0041] When camera 108 captures a content image, light-emitting diode (LED) 116 is turned on. When camera 108 captures a background image, LED 116 is turned off. Although an example of a single LED 116 is provided and discussed for simplicity, LED 116 may include more than one LED connected in series, parallel, or a combination of series and parallel. LED 116 may be, for example, an IR LED (which emits light in the IR range between 700 nanometers and 1 millimeter) or another suitable type of LED.

[0042] Driver module 120 controls the switching of LED 116 by controlling the switching of switch circuit 124 to control the application of power to LED 116 from one or more power sources, such as power source 128. Power source 128 may include direct current (DC) voltage. Power source 128 may include a battery or be battery-based, such as a 12-volt vehicle battery or another suitable type of battery. In various specific embodiments, the power source may include a voltage converter that converts the voltage from another power source (e.g., a vehicle battery) into a voltage suitable for application to LED 116. Driver module 120 turns LED 116 on for content images and turns LED 116 off for background images. Driver module 120 thus turns LED 116 on and off at a predetermined LED frequency (e.g., corresponding to 10-55 times per second).

[0043] Imaging module 112 can perform one or more image processing functions based on the image captured by camera 108. For example, imaging module 112 can use a background image captured subsequently after the content image is captured to remove background illumination from the content image. Imaging module 112 can perform one or more functions based on the obtained content image. For example, imaging module 112 can determine whether an occupant is seated based on the obtained content image.

[0044] However, after LED 116 is powered off, it will continue to emit light naturally for a period of time. In other words, when the current flowing through LED 116 stops, LED 116 does not immediately turn off (and stop emitting light). This can be referred to as the afterglow of LED 116. If a background image is captured while LED 116 is still on (due to the afterglow), LED 116 may (artificially) enhance background illumination. This could affect image processing functions performed by imaging module 112, such as removing background illumination from the content image.

[0045] According to this application, driver module 120 minimizes or reduces the afterglow of LED 116. For example, driver module 120 may shunt the anode of LED 116 to a ground reference potential after power to LED 116 is disconnected. Additionally or alternatively, driver module 120 may connect the anode of LED 116 to a negative power supply after power to LED 116 is disconnected. Additionally or alternatively, driver module 120 may reverse power supply to LED 116 after power to LED 116 is disconnected (e.g., applying a positive reference potential to the cathode and applying a negative reference potential or ground to the anode).

[0046] Figure 2 This is a schematic diagram of an exemplary circuit for minimizing the afterglow of LED 116. Figure 2 In the example, the switching circuit 124 includes a first switch 204 (A) and a second switch 208 (B), and the driver module 120 minimizes afterglow by shunting the anode of the LED 116 to ground.

[0047] The first terminal 212 of the first switch 204 is connected to a positive (+) reference potential (e.g., +12 volts DC) from the power supply 128. The second terminal 216 of the first switch 204 is connected to node 220. The first switch 204 may be, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET) or another suitable type of switch.

[0048] The first terminal 224 of the second switch 208 is connected to node 220. The second terminal 228 of the second switch 208 is connected to node 232. The second switch 208 can be, for example, a MOSFET or another suitable type of switch. Node 232 is connected to a ground reference potential, such as the chassis ground of a vehicle. The negative reference potential of power supply 128 can also be connected to a ground reference potential.

[0049] The anode 236 of LED 116 is connected to node 220. The cathode 240 of LED 116 is connected to node 232.

[0050] Driver module 120 controls first switch 204 and second switch 208 to control LED 116. To turn on LED 116, driver module 120 closes first switch 204 (e.g., turns on first switch 204) and simultaneously opens second switch 208 (e.g., turns off second switch 208). To turn off LED 116 and minimize LED 116's afterglow, driver module 120 closes second switch 208 (e.g., turns on second switch 208) and simultaneously opens first switch 204 (e.g., turns off first switch 204). Below is an exemplary table illustrating the states of first switch 204 and second switch 208 for turning LED 116 on and off.

[0051]

[0052] Figure 3 This is a schematic diagram of an exemplary circuit for minimizing the afterglow of LED 116. Figure 3 In the example, the switching circuit 124 includes a first switch 304 (A) and a second switch 308 (B), and the driver module 120 minimizes afterglow by applying a negative reference potential to the LED 116.

[0053] The first terminal 312 of the first switch 204 is connected to a positive (+) reference potential (e.g., +12 volts DC) from the power supply 314. The second terminal 316 of the first switch 304 is connected to node 320. The first switch 304 may be, for example, a MOSFET or another suitable type of switch.

[0054] The first terminal 324 of the second switch 308 is connected to node 320. The second terminal 328 of the second switch 208 is connected to the negative reference potential of the power supply 306. The second switch 308 can be, for example, a MOSFET or another suitable type of switch.

[0055] The negative reference potential of power supply 314 is connected to node 332. The positive reference potential of power supply 306 (e.g., +12V DC) is also connected to node 332. In this example, power supply 128 includes power supply 306 and power supply 314.

[0056] The anode 336 of LED 116 is connected to node 320. The cathode 340 of LED 116 is connected to node 332.

[0057] Driver module 120 controls first switch 304 and second switch 308 to control LED 116. To turn on LED 116, driver module 120 closes first switch 304 (e.g., turns on first switch 304) and simultaneously opens second switch 308 (e.g., turns off second switch 308). To turn off LED 116 and minimize its afterglow, driver module 120 closes second switch 308 (e.g., turns on second switch 308) and simultaneously opens first switch 304 (e.g., turns off first switch 304). Driver module 120 maintains second switch 308 closed and first switch 304 open for a predetermined afterglow period. LED 116 is completely turned off after the predetermined afterglow period. Once the predetermined afterglow period has passed, driver module 120 turns second switch 308 off and keeps first switch 304 open.

[0058] Below is an exemplary table showing the states of the first switch 304 and the second switch 308 for turning LED 116 on and off.

[0059]

[0060] Figure 4 This is a schematic diagram of an exemplary circuit for minimizing the afterglow of LED 116. Figure 4 In the example, the switching circuit 124 includes a first switch 404 (A), a second switch 408 (B), a third switch 412 (C), and a fourth switch 416 (D). The driver module 120 minimizes afterglow by reversing the power supply to the LED 116 (by applying a positive reference potential to the cathode and a negative reference potential to the anode or grounding).

[0061] The positive (+) reference potential of power supply 128 (e.g., +12V DC) is connected to node 420. The negative (-) reference potential of power supply 128 is connected to node 422. Node 422 is connected to a ground reference potential, such as the chassis ground of a vehicle.

[0062] The first terminal 424 of the first switch 404 is connected to node 420. The second terminal 428 of the first switch 404 is connected to node 432. The first switch 404 may be, for example, a MOSFET or another suitable type of switch.

[0063] The first terminal 436 of the third switch 412 is connected to node 432. The second terminal 440 of the third switch 412 is connected to node 422. The third switch 412 can be, for example, a MOSFET or another suitable type of switch.

[0064] The first terminal 444 of the second switch 408 is connected to node 420. The second terminal 448 of the second switch 408 is connected to node 452. The second switch 408 can be, for example, a MOSFET or another suitable type of switch.

[0065] The first terminal 456 of the fourth switch 416 is connected to node 452. The second terminal 460 of the fourth switch 416 is connected to node 422. The fourth switch 416 can be, for example, a MOSFET or another suitable type of switch.

[0066] The anode 464 of LED 116 is connected to node 432. The cathode 468 of LED 116 is connected to node 452. In this example, the first switch 404, the second switch 408, the third switch 412, and the fourth switch 416 form a bridge.

[0067] Driver module 120 controls first switch 404, second switch 408, third switch 412, and fourth switch 416 to control LED 116. To turn on LED 116, driver module 120 closes first switch 404 and fourth switch 416 (e.g., turns on first switch 404 and fourth switch 416) and simultaneously opens second switch 408 and third switch 412 (e.g., turns off second switch 408 and third switch 412). To turn off LED 116 and minimize its afterglow, driver module 120 closes second switch 408 and third switch 412 (e.g., turns on second switch 408 and third switch 412) and simultaneously opens first switch 404 and fourth switch 416 (e.g., turns off first switch 404 and fourth switch 416). Driver module 120 keeps second switch 408 and third switch 412 closed and keeps first switch 404 and fourth switch 416 open for a predetermined afterglow period. LED 116 is completely turned off after a predetermined afterglow period. Once the predetermined afterglow period has passed, driver module 120 turns the second switch 408 and the third switch 412 off and keeps the first switch 404 off. Driver module 120 can also keep the fourth switch 416 off or turn the fourth switch 416 off after the predetermined afterglow period has passed.

[0068] Below is an exemplary table illustrating the states of the first switch 404, the second switch 408, the third switch 412, and the fourth switch 416 used to turn the LED 116 on and off.

[0069]

[0070] In the table above, for LED off (after a predetermined afterglow period), driver module 120 can set both third (C) switch 412 and fourth (D) switch 416 to on or off. When first (A) switch 404 and second (B) switch 408 are both off, the states of third (C) switch 412 and fourth (D) switch 416 are irrelevant, and LED 116 will be off. Furthermore, if third (C) switch 412 and fourth (D) switch 416 are off, driver module 120 can control first (A) switch 404 and second (B) switch 408 to be on or off. In other words, if the top switch is off, LED 116 will be off regardless of the state of the bottom switch. Conversely, if the bottom switch is off, LED 116 will be off regardless of the state of the top switch.

[0071] Figure 5 This is a flowchart depicting an exemplary method of turning LED 116 on and off while minimizing the afterglow of LED 116. Control begins at 504, where driver module 120 actuates switching circuit 124, causing (positive) current to flow through LED 116, and LED 116 is turned on and illuminates. Imaging module 112 can cause driver module 120 to turn on LED 116 for capturing a content image.

[0072] At 508, imaging module 112 determines whether to capture a content image. For example, imaging module 112 may determine whether a predetermined period of time has elapsed since the last (e.g., background) image was captured. If 508 is true, control continues to 512. If 508 is false, control returns to 504 and driver module 120 keeps LED 116 on.

[0073] At 512, imaging module 112 actuates camera 108 to capture a content image. At 516, after the content image has been captured, driver module 120 actuates switching circuit 124 to turn off LED 116 and minimize the afterglow of LED 116. Imaging module 112 can cause driver module 120 to turn off LED 116 to capture a background image. Driver module 120 can control switching circuit 124, as described above. Figure 2 , Figure 3 or Figure 4 The example described.

[0074] At 520, imaging module 112 determines whether to capture the background image. For example, imaging module 112 may determine whether a predetermined period of time has elapsed since the last (e.g., content) image was captured (e.g., at 512). If 520 is true, control continues to 524. If 520 is false, control returns to 516 and driver module 120 keeps LED 116 off. At 524, imaging module 112 actuates camera 108 to capture the background image. Imaging module 112 may perform one or more image processing functions on the content image (e.g., captured at 512) and the background image (e.g., captured at 524). For example, imaging module 112 may remove background illumination from the content image based on background illumination in the background image. Control may return to 504.

[0075] The foregoing description is merely illustrative in nature and is by no means intended to limit this disclosure, its application, or its use. The broad teachings of this disclosure can be implemented in many forms. Therefore, while this disclosure includes specific examples, its true scope should not be so limited, as other modifications will become apparent upon examination of the drawings, specification, and appended claims. It should be understood that one or more steps within the method may be performed in a different order (or simultaneously) without altering the principles of this disclosure. Furthermore, while each embodiment of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of this disclosure may be implemented in and / or combined with features of any other embodiment, even if such combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and substitution of one or more embodiments for each other remains within the scope of this disclosure.

[0076] Spatial and functional relationships between components (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connection,” “joint,” “coupled,” “adjacent,” “closely adjacent,” “on top of,” “above,” “below,” and “set.” Unless explicitly described as “direct,” when describing the relationship between a first component and a second component in the above disclosure, the relationship can be a direct relationship in which no other intervening component exists between the first component and the second component, or an indirect relationship in which one or more intervening components exist between the first component and the second component (spatially or functionally). As used herein, at least one of the phrases A, B, and C should be interpreted as meaning the logic of using the non-exclusive logic “OR” (A or B or C), and should not be interpreted as meaning “at least one of A, at least one of B, and at least one of C.”

[0077] In the accompanying drawings, as indicated by the arrows, the direction of the arrows generally indicates the flow of information of interest (e.g., data or instructions). For example, when components A and B exchange various information, but the information sent from component A to component B is relevant to the illustration, the arrow can point from component A to component B. This unidirectional arrow does not imply that no other information is being sent from component B to component A. Furthermore, for information sent from component A to component B, component B can send a request for or confirmation of receipt of that information to component A.

[0078] In this application, including the following definitions, the term "module" or "controller" may be replaced by the term "circuit". The term "module" may refer to, be part of, or include the following: application-specific integrated circuit (ASIC); digital, analog, or mixed-signal analog / digital discrete circuit; digital, analog, or mixed-signal analog / digital integrated circuit; combinational logic circuit; field-programmable gate array (FPGA); processor circuitry (shared, dedicated, or grouped) that executes code; memory circuitry (shared, dedicated, or grouped) that stores code executed by the processor circuitry; other suitable hardware components that provide the described functionality; or some or all of the foregoing, such as in a system-on-a-chip.

[0079] A module may include one or more interface circuits. In some examples, the interface circuit may include a wired or wireless interface for connecting to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functionality of any given module disclosed herein may be distributed across multiple modules connected via the interface circuit. For example, multiple modules may allow for load balancing. In another example, a server (also known as a remote or cloud) module may perform some functions on behalf of a client module.

[0080] The term "code" as used above can include software, firmware, and / or microcode, and can refer to programs, routines, functions, classes, data structures, and / or objects. The term "shared processor circuitry" covers a single processor circuitry that executes some or all of the code from multiple modules. The term "grouped processor circuitry" covers processor circuitry that, in combination with additional processor circuitry, executes some or all of the code from one or more modules. References to multiprocessor circuitry cover multiple processor circuitry on a discrete die, multiple processor circuitry on a single die, multiple cores of a single processor circuitry, multiple threads of a single processor circuitry, or a combination of the above. The term "shared memory circuitry" covers a single memory circuitry that stores some or all of the code from multiple modules. The term "grouped memory circuitry" covers memory circuitry that, in combination with additional memory, stores some or all of the code from one or more modules.

[0081] The term memory circuit is a subset of the term computer-readable medium. As used herein, the term computer-readable medium does not cover transient electrical or electromagnetic signals propagated through a medium (such as on a carrier wave); therefore, the term computer-readable medium can be considered tangible and non-transient. Non-limiting examples of non-transient tangible computer-readable media are non-volatile memory circuits (such as flash memory circuits, erasable programmable read-only memory circuits, or mask read-only memory circuits), volatile memory circuits (such as static random access memory circuits or dynamic random access memory circuits), magnetic storage media (such as analog or digital magnetic tape or hard disk drives), and optical storage media (such as CDs, DVDs, or Blu-ray discs).

[0082] The apparatus and methods described in this application can be implemented, in part or in whole, by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. The function blocks, flowchart components, and other elements described above serve as software specifications that can be translated into computer programs by the routine work of a skilled technician or programmer.

[0083] A computer program includes processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. A computer program may also include or depend on stored data. A computer program may encompass a basic input / output system (BIOS) that interacts with the hardware of a special-purpose computer, device drivers that interact with specific devices of the special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0084] Computer programs may include: (i) descriptive text to be parsed, such as Hypertext Markup Language (HTML), Extensible Markup Language (XML), or JavaScript Object Notation (JSON); (ii) assembly code; (iii) object code generated from source code by a compiler; (iv) source code executed by an interpreter; and (v) source code compiled and executed by a just-in-time (JIT) compiler. As an example only, source code may come from languages ​​including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, and Java. ® , Fortran, Perl, Pascal, Curl, OCaml, Javascript ® Hypertext Markup Language 5th Revision (HTML5), Ada, Dynamic Server Pages (ASP), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash ® Visual Basic ®Lua, MATLAB, SIMULINK, and Python ® It is written using the syntax of the language.

Claims

1. A system for reducing the afterglow effect of a light-emitting diode, the system comprising: A light-emitting diode (LED) having an anode and a cathode; The switching circuit is configured as follows: When in the first state, the LED is turned on by connecting the anode of the LED to a positive reference potential and the cathode of the LED to a ground reference potential, thereby allowing current to flow through the LED in the first direction; as well as When in the second state, the LED is turned off by doing one of the following: The ground reference potential is shunted to the anode of the LED; Connect a negative reference potential to the anode of the LED; as well as The cathode of the LED is connected to the positive reference potential and the anode of the LED is connected to the ground reference potential, thereby allowing current to flow through the LED in the second direction. The second direction is opposite to the first direction; and A driver module configured to selectively transition the switching circuit from the first state to the second state and from the second state back to the first state.

2. The system of claim 1, wherein when in the second state, the switching circuit is configured to connect the ground reference potential to the anode of the LED.

3. The system according to claim 2, wherein: The switching circuit includes: A first switch, the first switch having a first terminal connected to the positive reference potential and a second terminal connected to the first node; A second switch, the second switch having a first terminal connected to the first node and a second terminal connected to the second node; The anode of the LED is connected to the first node; The cathode of the LED is connected to the second node; and The grounding reference potential is connected to the second node.

4. The system of claim 3, wherein the driver module is configured to: Close the first switch and open the second switch to operate the switching circuit in the first state; and Disconnect the first switch and close the second switch to operate the switching circuit in the second state.

5. The system of claim 1, wherein when in the second state, the switching circuit is configured to connect the negative reference potential to the anode of the LED.

6. The system according to claim 5, wherein: The switching circuit includes: A first switch, the first switch having a first terminal connected to the positive reference potential and a second terminal connected to the first node; A second switch, the second switch having a first terminal connected to the negative reference potential and a second terminal connected to the first node; and The second node is connected to the cathode of the LED; and The anode of the LED is connected to the first node.

7. The system of claim 6, wherein the driver module is configured to: The switching circuit is operated in the first state by closing the first switch and opening the second switch; and The switching circuit is operated in the second state by disconnecting the first switch and closing the second switch.

8. The system of claim 7, wherein the driver module is configured to: Keep the first switch open and the second switch closed for a predetermined afterglow period; and Once the predetermined afterglow period has passed, disconnect the second switch.

9. The system of claim 1, wherein when in the second state, the switching circuit is configured to connect the cathode of the LED to the positive reference potential and the anode of the LED to the ground reference potential, thereby enabling current to flow through the LED in the second direction.

10. The system according to claim 9, wherein: The switching circuit includes: A first switch, the first switch having a first terminal connected to the positive reference potential and a second terminal connected to the first node; A second switch, the second switch having a first terminal connected to the positive reference potential and a second terminal connected to a second node; A third switch, the third switch having a first terminal connected to the first node and a second terminal connected to the ground reference potential; and A fourth switch, the fourth switch having a first terminal connected to the second node and a second terminal connected to the ground reference potential; The anode of the LED is connected to the first node; and The cathode of the LED is connected to the second node.

11. The system of claim 10, wherein the driver module is configured to: The switching circuit is operated in the first state by closing the first switch and the fourth switch and opening the second switch and the third switch; and The switching circuit is operated in the second state by disconnecting the first switch and the fourth switch and closing the second switch and the third switch.

12. The system of claim 11, wherein the driver module is configured to: Keep the first switch and the fourth switch open and the second switch and the third switch closed for a predetermined afterglow period; and Once the predetermined afterglow period has passed, disconnect the second switch and the third switch.

13. The system of claim 12, wherein the driver module is further configured to close the fourth switch once the predetermined afterglow period has passed.

14. The system of claim 1, wherein the LED is configured to emit light with a wavelength between 700 nanometers (nm) and 1 millimeter (mm).

15. The system according to claim 1, further comprising: camera; and Imaging module, the imaging module being configured as follows: When the switching circuit is in the first state, the camera is actuated and the first image is captured using the camera; as well as When the switching circuit is in the second state, the camera is actuated and a second image is captured using the camera.

16. The system of claim 15, wherein the imaging module is configured to actuate the camera and capture images at a predetermined frequency. The predetermined frequency is at least 10 Hz.

17. The system of claim 16, wherein the driver module is configured to switch the switching circuit from the second state to the first state at the predetermined frequency.

18. The system of claim 15, wherein the imaging module is configured to adjust the first image using the second image.

19. The system of claim 15, wherein the camera is an infrared (IR) camera and is configured to capture images of the passenger compartment of the vehicle.

20. A method for reducing the afterglow effect of a light-emitting diode, the method comprising: In the first state, the switching circuit is selectively operated to turn on the light-emitting diode (LED) by performing the following operations: Connect the anode of the LED to a positive reference potential; Connect the cathode of the LED to a ground reference potential; as well as This allows current to flow through the LED in the first direction; as well as In the second state, the switching circuit is selectively operated to turn off the LED by performing one of the following operations: The ground reference potential is shunted to the anode of the LED; Connect a negative reference potential to the anode of the LED; as well as The cathode of the LED is connected to the positive reference potential, and the anode of the LED is connected to the ground reference potential, such that current can flow through the LED in a second direction. Wherein the second direction is opposite to the first direction; and The switching circuit is selectively switched from the first state to the second state and from the second state to the first state.

Images