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    • 专利摘要:
    led backlight system. the invention relates to a method and system for modifying the pulse width modulation frequency to control the backlight illumination intensity of a liquid crystal display (14). the modified pulse width modulation frequency can be selected to reduce distortion on the display (14) while allowing a wide range of dimming settings for the display (14). a pulse width modulation signal (95) can also be shifted in phase so that a chain of light sources (110-115) can be sequentially activated to generate an effective frequency greater than that of the frequency of the modulation signal pulse width (95).
    公开号:BR112012016743B1
    申请号:R112012016743-0
    申请日:2010-08-31
    公开日:2021-04-06
    发明作者:Paul M. Thompson；Floriano Kim；Mark A. Yoshimoto
    申请人:Apple Inc.；
    IPC主号:
    专利说明:

    [0001] [0001] This description generically refers to controlling the backlight illumination source of a liquid crystal display.
    [0002] [0002] This section intends to introduce the reader to various aspects of the technique that may be related to various aspects of the present description, which are described and / or claimed below. This discussion is believed to be useful in providing the reader with fundamental information to facilitate a better understanding of the various aspects of this description. Consequently, it must be understood that these statements should be read in this light, and not as admissions to the prior art.
    [0003] [0003] Electronic devices increasingly include display screens as part of the device's user interface. As can be appreciated, display screens can be employed in a wide device network, including desktop computer systems, notebook computers, and portable computing devices, as well as various consumer products such as cell phones and portable media players. Liquid crystal display (LCD) panels have become increasingly popular for use on display screens. This popularity can be attributed to its light weight and slim profile, as well as the relatively low energy it consumes to operate the LCD pixels.
    [0004] [0004] The LCD typically makes use of backlighting because the LCD does not emit light by itself. Backlight illumination typically involves supplying the LCD with light from a fluorescent cathode lamp or light emitting diodes (LEDs). To reduce energy consumption, LED clusters can be used so that the clusters are activated individually. However, this setting can lead to reduced resolution, distortion or artifacts, and / or limited brightness adjustment ranges. Therefore, there is a need to control the LEDs on an LCD using techniques that minimize loss of resolution, reduce distortion or artifacts as well as allow wide ranges of dimming for the LCD. SUMMARY
    [0005] [0005] A summary of certain modalities described here is presented below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain modalities and that these aspects are not intended to limit the scope of this description. Indeed, this description can cover a variety of aspects that may not be presented below.
    [0006] [0006] The present description generally refers to a backlight unit for a display device, such as an LCD display. In one embodiment, a backlit unit illuminated at the edge can include an LED chain architecture, each with a number of light sources per chain. For example, a group of six LED chains each with 3 LEDs in it can be used. The control of the activation and deactivation of the chains can be generated through a pulse width modulator (a pulse width modulation device). The chains can be activated in such a way that the first chain is activated, followed by the second chain, and so on. The activation of these chains can cause the LEDs on them to emit light. Furthermore, the strings can be activated at a relatively high frequency, such as 8 kHz. The frequency of 8 kHz of the strings combined with a total number of strings used, such as 6 strings, can generate an effective frequency (or equivalent) of 48 kHz on the display. BRIEF DESCRIPTION OF THE DRAWINGS
    [0007] [0007] Several aspects of this description can be better understood when reading the following detailed description and with reference to the drawings in which:
    [0008] [0008] Figure 1 is a perspective view illustrating an electronic device, according to an embodiment of the present invention;
    [0009] [0009] Figure 2 is an exploded perspective view of an LCD, according to an embodiment of the present invention;
    [0010] [00010] Figure 3 is a perspective view illustrating an LCD that can be used in the electronic device of Figure 1, according to an embodiment of the present invention;
    [0011] [00011] Figure 4 is a simplified block diagram illustrating the components of the electronic device of Figure 1, according to an embodiment of the present invention;
    [0012] [00012] Figure 5 is a block diagram illustrating the components for controlling the backlight intensity of the LCD of Figure 3, according to an embodiment of the present invention;
    [0013] [00013] Figure 6 is a first time sequence that can be applied to an LCD light source of Figure 3, according to an embodiment of the present invention;
    [0014] [00014] Figure 7 is a second time sequence that can be applied to an LCD light source of Figure 3, according to an embodiment of the present invention;
    [0015] [00015] Figure 8 is a flow chart illustrating the operation of the components of Figure 5, according to an embodiment of the present invention;
    [0016] [00016] Figure 9 is an additional time sequence that can be applied to an LCD light source of Figure 3, according to an embodiment of the present invention;
    [0017] [00017] Figure 10 is another time sequence that can be applied to an LCD light source of Figure 3, according to an embodiment of the present invention; and
    [0018] [00018] Figure 11 is a front view of the LCD display of Figure 3, according to an embodiment of the present invention;
    [0019] [00019] Figure 12 is a top view of a light source of Figure 3, according to an embodiment of the present invention; and
    [0020] [00020] Figure 13 is a top view of the light source of Figure 3, according to an embodiment of the present invention. DETAILED DESCRIPTION OF SPECIFIC MODALITIES
    [0021] [00021] One or more specific modalities will be described below. In an effort to provide a concise description of these modalities, not all of the characteristics of an actual implementation are described in the specification. It should be appreciated that in the development of any such real implementation, as in any engineering or design project, numerous specific implementation decisions must be made to achieve the specific objectives of the developers, such as compliance with system and relative constraints. to businesses, which may vary from one implementation to another. Furthermore, it should be appreciated that such a development effort can be complex and time-consuming, but it would nonetheless be a routine design, manufacturing, and manufacturing obligation for those skilled in the art having the benefit of this description.
    [0022] [00022] The order is generally directed at a method and system for controlling the backlight of a display. A pulse width modulator (PWM) signal can be transmitted to a display. By controlling the duty cycle of the PWM signal, the display brightness can be adjusted. Furthermore, the PWM signal can be provided for each of a group of LED chains, each with a series of LEDs on it. The PWM signal can be provided for the LED chains, for example, in a sequential mode. The frequency at which the PWM signal can be transmitted to each of the LED chains can be a relatively high frequency, for example, 8 kHz. Quickly transmitting the PWM signal to the LED chains in this way can reduce the visual artifacts on the display while maintaining a reduced total power consumption of the display, since less than all chains can be activated at any given time. Furthermore, the PWM signal can be lagged to allow the generation of an effective frequency on the display at a higher rate than the frequency of the PWM signal.
    [0023] [00023] An electronic device 10 is illustrated in Figure 1 according to an embodiment of the present invention. In some embodiments, including the presently illustrated embodiment, device 10 may be a portable electronic device, such as a laptop computer. Other electronic devices may also include an assistive media player, a cell phone, a personal data organizer, or the like. Indeed, in such embodiments, a portable electronic device may include a combination of the functionalities of such devices. In addition, electronic device 10 may allow a user to connect and communicate over the Internet or over other networks, such as local or wide area networks. For example, the portable electronic device 10 may allow a user to access the Internet and communicate using e-mail, text message, or other forms of electronic communication. As an example, electronic device 10 may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. of Cupertino, California. In other modalities, the electronic device may include other models and / or types of electronic devices that employ LED backlights, available from any manufacturer.
    [0024] [00024] In certain embodiments, the electronic device 10 can be powered by one or more rechargeable and / or replaceable batteries. Such modes can be highly portable, allowing a user to charge the electronic device 10 while traveling, working and so on. Although certain embodiments of the present invention are described with respect to a portable electronic device, it should be noted that the techniques presently described may be applicable to a wide network of other electronic devices and systems that are configured to render graphic data, such as a computer. desktop.
    [0025] [00025] In the modality presently illustrated, the electronic device 10 includes a wrap or housing 12, a display 14, input structures 16, and input / output (I / O) ports or connectors 18. The wrap 12 can be formed from plastic, metal, composite materials, or other suitable materials, or any combination thereof. The wrapper 12 can protect the internal components of the electronic device 10, such as processors, circuits, and controllers, among others, from physical damage, and can also shield the internal components from electromagnetic interference (EMI).
    [0026] [00026] Display 14 can be a liquid crystal display (LCD). The LCD can be a display based on a light emitting diode (LED) or some other suitable display. As noted above, electronic device 10 can also include input structures 16. In one embodiment, one or more of the input structures 16 are configured to control device 10, such as controlling an operating mode, an output level, a output type, etc. For example, the input structures 16 can include a button to turn the device 10 on or off. Furthermore, the input structures 16 can allow a user to increase or decrease the brightness of the display 14. The modalities of the portable electronic device 10 can include any number of input structures 16, including buttons, computers, a control panel, a keyboard, or any other suitable input structure that can be used to interact with the electronic device 10. These input structures 16 can operate to control the functions of the electronic device 10 and / or any interfaces or devices connected to or used by electronic device 10. For example, input structures 16 may allow a user to navigate through a displayed user interface, such as a graphical user interface (GUI) , and / or other applications that run on the electronic device 10.
    [0027] [00027] Device 10 can also include multiple I / O ports 18 to allow additional devices to be connected. For example, device 10 can include any number of input and / or output ports 18, such as headphone and headphone connectors, universal serial bus (USB) ports, IEEE-1394 ports, Ethernet ports, and modem, AC and / or DC power connectors. In addition, electronic device 10 can use I / O ports 18 to connect and send or receive data with any other device, such as a modem, networked computers, printers, or the like. For example, in one embodiment, electronic device 10 can connect to an iPod via a USB connection to send and receive data files, such as media files.
    [0028] [00028] The additional details of the display 14 can be better understood by reference to Figure 2, which is an exploded perspective view of an example of the LCD type display 14. The display 14 includes a top cover 20. The cover upper 20 may be formed of plastic, metal, composite materials, or other suitable materials, or any combination thereof. In one embodiment, the top cover 20 is a frame. The upper cover 20 can also be formed in such a way as to combine with the lower cover 38 to provide a support structure for the remaining elements illustrated in Figure 2. A liquid crystal display panel (LCD) 22 is also illustrated. The LCD panel 22 can be arranged below the top cover 20. The LCD panel 22 can be used to display an image using a liquid crystal substance typically arranged between two substrates. For example, a voltage can be applied to electrodes, which reside on or on or within the substrates, creating an electric field through liquid crystals. The liquid crystals change alignment in response to the electric field, thereby modifying the amount of light that can be transmitted through the liquid crystal substance and viewed at a specified pixel. In such a way, and through the use of several color filters to create the colored sub-pixels, the color images can be represented through individual pixels of the display 14 in a pixelated mode.
    [0029] [00029] The LCD panel 22 may include a group of individually addressable pixels. In one embodiment, the LCD panel 22 may include one million pixels, divided into lines of pixels each including a thousand pixels. The LCD panel 22 may also include a passive or active display matrix or grid used to control the electric field associated with each individual pixel. In one embodiment, the LCD panel 22 may include an active matrix that uses thin film transistors arranged along pixel intersections of a grid. Through switching actions of thin film transistors, the pixel luminance of the LCD panel 22 can be controlled. The LCD panel 22 may also include several additional components, such as polarization films and anti-glare films.
    [0030] [00030] The display 14 can also include optical plates 24, the optical plates 24 can be arranged below the LCD panel 22 and can condense the light that passes to the LCD panel 22. In one embodiment, the optical plates 24 can be prism plates which can act to angularly shape the light that passes through the LCD panel 22. Optical plates 24 can include or one or more plates. The display 14 can also include a diffuser plate or plate 26. The diffuser plate 26 can be arranged below the LCD panel 22 and can also be arranged or above or below the optical plates 24. The diffuser plate 26 can diffuse the light that is being passed to LCD panel 22. Diffuser plate 26 can also reduce glare and non-uniform illumination over LCD panel 22. A guide plate 28 can also help to reduce non-uniform illumination over LCD panel 22 In one embodiment, the guide plate 28 is part of an edge-type backlight assembly. In an edge type backlight assembly, a light source 30 can be arranged along one side of the guide plate 28, such as the bottom edge 32 of the guide plate 28. The guide plate 28 can act to channel the light emanating from the light source 30 upwards towards the LCD panel 22.
    [0031] [00031] Light source 30 can include light emitting diodes (LEDs) 34. LEDs 34 can be a combination of red, blue, and green LEDs, or LEDs 34 can be white LEDs. In one embodiment, LEDs 34 may be arranged on a printed circuit board (PCB) 36 adjacent to an edge of the guide plate 28, such as the bottom edge 32, as part of an edge-type backlight assembly . In another embodiment, the LEDs 34 can be arranged on one or more PCBs 36 along the inner surface of the bottom cover 38. For example, the one or more PCBs 36 can be aligned along an inner side 40 of the bottom cover 38. The LEDs 34 can be arranged in one or more chains, whereby a number of the LEDs 34 are coupled in series with each other in each chain. For example, LEDs 34 can be grouped into six chains, whereby each chain includes three LEDs 34 connected in series. However, it should be noted that as few as one or two LEDs 34 can be connected on each chain or more than three LEDs 34, such as six LEDs, can be connected on each chain. Furthermore, the chains can be positioned in an end-to-end configuration, a side-by-side configuration, and / or any other suitable configuration.
    [0032] [00032] The display 14 can also include a reflective plate or plate 42. The reflective plate 42 is generally disposed below the guide plate 28. The reflective plate 42 acts to reflect the light that has passed down through the guide plate 28 of back towards the LCD panel 22. In addition, the display includes a lower opening 38, as previously discussed. The bottom cover 38 can be formed in such a way as to combine with the top cover 20 to provide a support structure for the remaining elements illustrated in Figure 2. The bottom cover 38 can also be used in a backlight type set. direct light, whereby one or more light sources 30 are located on a lower edge 43 of the lower cover 38. In this configuration, instead of using a light source 30 positioned adjacent to the diffuser plate 26 and / or guide plate 28, the reflective plate 42 can be omitted and one or more light sources (not shown on the bottom edge 43 of the bottom cover 38 can emit light directly towards the LCD panel 22.
    [0033] [00033] Figure 3 shows a display modality 14 that uses a backlight illuminated at the edge. The display 14 includes the LCD panel 22 held in place, as illustrated, by the top cover 20. As described above, the display 14 can use a backlight assembly so that a light source 30 can include the LEDs 34 mounted on, for example, a Metallic Core Printed Circuit Board (MCPCB), or other suitable type of support located on a network tray 44 in the display 14. This network tray 44 can be attached to the top cover 20 so that the light source 30 is positioned inside the display 14 for the generation of light, which can be used to generate the images on the LCD panel 22.
    [0034] [00034] The light source 30 may also include a circuit required to translate an input voltage into an LED voltage usable to power the LEDs 34 of the light source 30. As the light source 30 can be used in a portable device , it is desirable to use as little energy as possible to increase the battery life of the electronic device 10. To conserve energy, the light source 30, that is, the LEDs 34 on it, can be switched on and off. In this way, the energy in the system can be conserved because the light source 30 does not need to be energized continuously. Furthermore, this switching will appear to create constant images for an observer if the switching frequency is maintained above at least one scintillation fusion frequency of the human eye, approximately 30 Hz.
    [0035] [00035] In addition to conserving energy by adjusting the duty cycle (the ratio of time that the light source 30 is on in relation to the amount of time that the light source 30 is on and off) of the switched light source 30, the total brightness of the LCD panel 22 can be controlled. For example, a 50% duty cycle would result in an image being displayed at approximately half the brightness of constant backlight illumination. In another example, a 20% duty cycle results in an image being displayed at approximately 20% of the brightness that a constant backlight illumination would provide. Thus, by adjusting the duty cycle of a switched signal, the brightness of a displayed image can be adjusted with the additional benefit of reducing the energy consumed in the electronic device 10.
    [0036] [00036] The internal components of the electronic device 10 can be used to perform the switching of the light source 30 on the LCD panel 22. Figure 4 is a block diagram illustrating the components that can be used to perform the switching procedure described above. Those skilled in the art will appreciate that the various function blocks shown in Figure 4 can include hardware elements (including circuits), software elements (including a computer code stored in a machine-readable medium) or a combination of both hardware and hardware elements. software. It should also be noted that Figure 4 is merely an example of a specific implementation, other examples could include components used in Apple products such as an iPod®, MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro®, iPhone®, or other electronic device that uses an LCD.
    [0037] [00037] In the presently illustrated modality of the electronic device 10, the components may include the display 14, the input structures 16, the I / O ports 18, one or more processors 46, a memory device 48, a non-volatile storage 50, expansion card (s) 52, a network device 54, a power source 56, and a display control logic 58. With reference to each of these components, it is first noted that display 14 can be used to display multiple images generated by the device 10 and can be provided together with a touch sensitive element, such as a touch screen, which can be used as part of the control interface for the device 10.
    [0038] [00038] Input structures 16 can include various devices, circuits, and paths through which user input or feedback is provided to processor (s) 46. Such input structures 16 can be configured to control a function of the electronic device 10, the applications running on the device 10, and / or any interfaces or devices connected to or used by the device 10. For example, input structures 16 may allow a user to navigate a user interface or interface displayed application. Non-limiting examples of input structures 16 include buttons, sliders, switches, control keypad, key, rotary buttons, navigation wheels, keyboards, mice, touch keyboards, and so on. User interaction with input structures 16, in order to interact with a user or application interface shown on display 12, can generate electrical signals indicative of user input. These input signals can be routed through suitable paths, such as an input hub or bus, to processor (s) 46 for further processing.
    [0039] [00039] In addition, in certain embodiments, one or more input structures 16 can be provided together with the display 14, such as in the case of a touch screen, in which a touch-sensitive mechanism is provided together with the display 14. In such modalities, the user can select or interact with the interface elements displayed through the touch-sensitive mechanism. In this way, the displayed interface can provide interactive functionality, which allows a user to navigate the displayed interface by touching the display 14.
    [0040] [00040] As noted above, I / O ports 18 may include ports configured to connect to a variety of external devices, such as a power source, headset or headset, or other electronic devices (such as devices laptops and / or computers, printers, projectors, external displays, modems, docking stations, and so on). I / O ports 18 can support any type of interface, such as a universal serial bus (USB) port, a video port, a serial connection port, an IEEE-1394 port, an Ethernet or modem port, and / or an AC / DC power connection port.
    [0041] [00041] Processor (s) 46 may provide the processing power to execute the operating system, the programs, the user and application interfaces, and any other functions of the electronic device 10. O ( s) processor (s) 46 may include one or more microprocessors, such as one or more "general purpose" microprocessors, one or more special use microprocessors and / or ASICS, or some combination of such processing components. For example, processor (s) 46 may (46) may include one or more reduced instruction set (RISC) processors, as well as graphics processors, video processors, audio processors, and the like. As it will be appreciated, the processor (s) 46 may be communicatively coupled to one or more data buses or chip sets to transfer the data and instructions between various components of the electronic device 10.
    [0042] [00042] The programs or instructions executed by the processor (s) 46 may be stored in any suitable manufacture that includes one or more tangible means, computer-readable at least collectively storing the executed instructions or routines, such as , but not limited to, the memory devices and storage devices described below. Also, these programs (for example, an operating system, encoded in such a computer program product, may also include instructions that can be executed by processor (s) 46 to allow device 10 to provide various functionalities, including those described here.
    [0043] [00043] Instructions or data to be processed by processor (s) 46 may be stored in a computer-readable medium, such as memory 48. Memory 48 may include volatile memory, such as a random access memory (RAM), and / or a non-volatile memory, such as a read-only memory (ROM). Memory 48 can store a variety of information and can be used for a variety of purposes. For example, memory 48 can store firmware for electronic device 10 (such as a basic input / output system (BIOS)), an operating system, and various other programs, applications, or routines that can be run on the device electronic 10. In addition, memory 48 can be used to store or cache during the operation of the electronic device 10.
    [0044] [00044] The components of the device 10 may further include other forms of computer-readable media, such as non-volatile storage 50 for persistent storage of data and / or instructions. Non-volatile storage 50 may include, for example, an instant memory, a hard disk or any other optical, magnetic, and / or solid state storage media. Non-volatile storage 50 can also be used to store firmware, data files, software programs, wireless information, and any other suitable data.
    [0045] [00045] The modality illustrated in Figure 4 can also include one or more card or expansion connectors. The card connectors can be configured to receive one or more expansion cards 52 that can be used to add functionality, such as additional memory, I / O functionality, or network capability, to the electronic device 10. Such cards expansion cards 52 can connect to device 10 via any type of suitable connector and can be accessed internally or externally to the housing of electronic device 10. For example, in one embodiment, expansion cards 52 may include an instant memory card, such as a SecureDigital (SD) card, mini or microSD, CompactFlash card, Multimedia card (MMC), or similar. In addition, expansion cards 52 may include one or more processor (s) 46 from device 10, such as a graphics video card that has a GPU to facilitate graphical rendering by device 10.
    [0046] [00046] The components shown in Figure 4 also include a network device 54, such as a network controller or a network interface card (NIC), internal to device 10. In one embodiment, network device 54 can be a wireless NIC that provides wireless connectivity over any 802.11 standard or any other suitable wireless network standard. Network device 54 may allow electronic device 10 to communicate over a network, such as a personal area network (PAN), a local area network (LAN), a wide area network (WAN), or the Internet. In addition, electronic device 10 can connect and send or receive data with any device on the network, such as portable electronic devices, personal computers, printers, and so on via network device 54. Alternatively, in some embodiments, the electronic device 10 may not include a network device 54. In such an embodiment, a NIC can be added as an expansion card 52 to provide similar network capability as described above.
    [0047] [00047] In addition, device 10 may also include a power source 56. In one embodiment, power source 56 may be one or more batteries, such as a lithium-ion polymer battery or other suitable type of battery. The battery can be removable by the user or it can be secured inside the housing of the electronic device 10, and it can be rechargeable. In addition, power source 56 may include AC power, as provided by an electrical outlet, and electronic device 10 may be connected to power source 56 via a power adapter. This power adapter can also be used to recharge one or more batteries of device 10. In addition, as shown in Figure 4, power source 56 can transmit power to display 14 via path 57. The use of this energy by the display 14 can be regulated by the display control logic 58, as discussed below.
    [0048] [00048] The display control logic 58 can be coupled to display 14 and can be used to control light source 30 from display 14. Alternatively, the display control logic can be internal to display 14. In one mode, the display control logic 58 can act to switch the light source 30 on and off. This switching, for example, can be used to decrease the total brightness of the display 14 when power source 56, such as a battery, is being used. In addition or alternatively, when the power source 56 is an AC power source, the total brightness of the display 14 can be modified simply by raising and / or lowering the constant voltage level supplied to the light source 30.
    [0049] [00049] In one embodiment, the control of the brightness level of the display 14 can be adjusted by changing the duty cycle of an activation signal transmitted to the light source 30. For example, if the duty cycle of the signal activation was 0%, then light source 30 would remain off and display 14 would be dark. On the contrary, if the duty cycle of the activation signal was 100%, then the display 14 would be in full brightness because the light source 30 would always be active (however, as much energy would be consumed as was used in the example of energy source CA above). In another example, if the duty cycle of the activation signal was 50%, the display 14 would be at half the brightness of the display 14 being always on, however, the energy consumption of the display could be reduced as much as 50% versus the light source 30 being continuously and fully powered.
    [0050] [00050] In addition, in one mode, the control of the brightness level of the display 14 can be adjusted by changing the duty cycle of an activation signal transmitted to the light source 30 together with an adjustment of the amount of current transmitted to the light source 30. This adjustment of the transmitted current to, for example, the LED chains of the light source, can occur when the duty cycle of an activation signal (such as a PWM signal) must be adjusted below a threshold level. For example, if desired, the brightness of display 14 would require the duty cycle of the activation signal to be less than, for example, 20%, then the duty cycle can be adjusted to 20% and the current transmitted to the chains. active LEDs of the light source 30 can be reduced. In this way, the brightness of the display can be adjusted by controlling both the duty cycle of an activation signal and by controlling the current transmitted to the light source 30.
    [0051] [00051] In one embodiment, a pulse width modulator (PWM) 60 can provide the activation signal for light source 30 as a PWM signal. Furthermore, the duty cycle of the PWM signal can be adjusted in response to the user initiating changes in the brightness of the display 14 through, for example, inputs 16. In another mode, as described above, the display control logic 58 can be used to automatically adjust the brightness of the display 14 by varying the duty cycle of the PWM signal when the power source 56 is a battery. For example, the duty cycle of the PWM signal can be adjusted based on the amount of internal energy remaining in the battery.
    [0052] [00052] In one embodiment, the display control logic 58 can be coupled to the pulse width modulator (PWM) 60, which can generate a PWM signal. Alternatively, in one embodiment, the PWM 60 can be internal to the display control logic 58. The PWM signal generated by the PWM 60 can be an oscillating signal used to switch the light source 30 on and off. Furthermore, the duty cycle of the PWM signal can be selectable and can vary anywhere from 0-100%. As previously described, the duty cycle of the PWM signal can determine the total brightness of the display 14. In this way, the PWM signal can also reduce the total power consumption of the display 14 by controlling the amount of time that the LEDs 34 of the source of light 30 are "on" for any period of time. The PWM signal can also provide a high brightness resolution (i.e., at least a 10-bit resolution) on device 10. That is, the PWM signal can allow 1024 different levels of light to be achieved by the light source 30 .
    [0053] [00053] Figure 5 is a block diagram illustrating the components that control the backlight illumination intensity of the display 14. As noted above, the display control logic 58 can operate to control the time ratio that LEDs 34 of the light source 30 are on and off. In one embodiment, LEDs 34 can be activated in a sequential mode to control the total output of the light source 30. To perform this control of the light source 30, the display control logic 58 can include a sequencer 62. The sequencer 62 may, for example, be a microprocessor, one or more microprocessors for special use and / or ASICS, a controller, or some combination of such components. The sequencer can operate to receive a PWM signal generated by PWM 60 and received along path 64. In one embodiment, the PWM signal received from path 64 can be filtered, for example, by a low-pass filter 66 that includes a resistor 68 and a capacitor 70. Resistor 68 and capacitor 70 can be selected in such a way as to control the amount of uniformity of the PWM signal by the low-pass filter 66.
    [0054] [00054] Once the PWM signal is received by sequencer 62, a determination can be made as to which port control line 72-77 the PWM signal will be transmitted. It should be noted that although six port control lines 72-77 are illustrated, more or less than six port control lines can be used. As will be described in more detail below, each door control line 72-77 can control a dedicated door coupled to an individual LED chain used in the light source 30. That is, there may be a door control line and a door dedicated for each LED chain in the light source 30.
    [0055] [00055] Each of the 72-77 port control lines can be coupled to an individual port 78-83. Gates 78-83 can each be, for example, a field effect transistor (FET) such as a metal oxide semiconductor field effect transistor (MOSFET). Alternatively, the ports can include other types of switches, transistors, or other components that can connect and interrupt an electrical circuit. In the present mode, each port 78-83 can be activated by the signal transmitted along its corresponding port control line 72-77. For example, if the voltage is transmitted through the port control line 72, port 78 can be activated. That is, the voltage applied to port 78 can cause port 78 to operate as a closed switch allowing current to flow through port 78 along current path 84 to earth 86. Conversely, if no voltage is transmitted through from the port control line 72, port 78 can be disabled, causing port 78 to operate as an open switch, thereby preventing current from flowing along current path 84 through port 78 to earth 86.
    [0056] [00056] In addition, sequencer 62 may include a delay circuit 88. In one embodiment, delay circuit 88 may operate to maintain the PWM signal received along path 64 until sequencer 62 selects a control line from port 72-77 for PWM signal transmission. In this way, the sequencer can allow a lag of the PWM signal received along the path 64. In one embodiment, the amount of lag performed by the sequencer 62 can be equivalent to the period of the PWM signal divided by the total number of control lines of port 77-83 (that is, the total number of LED strings in the light source 30). For example, where six port control lines 77-83 exist, sequencer 62 can transmit the PWM signal unchanged to port control line 72. Subsequently, the sequencer can receive the lagged (delayed) PWM signal from the circuit delay time 88 equivalent to the period of the PWM signal delayed by 1/6 of the total period of the PWM signal and can transmit this lagged PWM signal to port control line 73. This process can continue for each of the control lines 74-77 port numbers, whereby each of the 74-77 port control lines receives a delayed PWM signal delayed by an additional 1/6 of the total period of the PWM signal, relative to the signal transmitted to the line previous door control 73-76. This process can be illustrated in Figure 6.
    [0057] [00057] Figure 6 illustrates a time sequence 90 that sequencer 62 can emit when used with delay circuit 88 to delay a received PWM signal, as described above. A pulse waveform 92 can represent the PWM signal received by sequencer 62 from path 64. In one embodiment, pulse waveform 92 can have a frequency of 8 kHz and a duty cycle of 50%. To phase pulse waveform 92, sequencer 62 can first transmit PWM waveform 92 along port control line 72 as pulse waveform 93. Next, sequencer 62 can transmit the pulse waveform 94 along port control line 73. As can be seen, pulse waveform 94 can be lagged by 1/6 (ie, 60 degrees) relative to the pulse waveform 92 (ie, the PWM signal). As noted above, this lag can be performed by delay circuit 88. Subsequently, sequencer 62 can transmit pulse waveform 95 along port control line 74. As can be seen, the pulse waveform 95 can be lagged by 1/6 (ie, 60 degrees) in relation to pulse waveform 94 and by 1/3 (ie, 120 degrees) in relation to pulse waveform 92 (ie, the PWM signal). This process can continue for the 96-98 pulse waveforms, transmitted along the 75-77 port control lines, respectively. That is, each of the 96-98 pulse waveforms can be lagged 60 degrees from the previous 95-97 waveform and the lag can be performed through delay circuit 88. The total lag effect with respect to to the 93-98 pulse waveforms can be such that the 8 kHz PWM 92 waveform can lead to an effective rate frequency (that is, the product of the frequency of the 93-98 pulse waveforms by the number total port control lines 72-77) of 48 kHz on display 14.
    [0058] [00058] Figure 7 illustrates a time sequence 100 and the sequencer 62 can emit when used with delay circuit 88 to delay a received PWM signal. Pulse waveform 102 may represent the PWM signal received by sequencer 62 from path 64. In one embodiment, pulse waveform 102 may have a frequency of 8 kHz and a duty cycle of 25%. To offset pulse waveform 102, sequencer 62 can first transmit PWM waveform 102 along port control line 72 as pulse waveform 103. Next, sequencer 62 can transmit the pulse waveform 104 along port control line 73. As can be seen, pulse waveform 104 can be lagged by 1/6 (ie, 60 degrees) relative to the pulse waveform 102 (that is, the PWM signal). As noted above, this lag can be performed by delay circuit 88. Subsequently, sequencer 62 can transmit pulse waveform 105 along port control line 74. As can be seen, the pulse waveform 105 can be lagged by 1/6 (ie, 60 degrees) in relation to pulse waveform 104 and by 1/3 (ie, 120 degrees) in relation to pulse waveform 102 (ie, the PWM signal). This process can continue for the 106-108 pulse waveforms, transmitted along the 75-77 port control lines, respectively. That is, each of the 106-108 pulse waveforms can be lagged 60 degrees from the previous 105-107 waveform and the lag can be performed through delay circuit 88. The total lag effect with respect to to the 103-108 pulse waveforms can be such that the 8 kHz PWM 102 waveform can lead to an effective rate frequency (that is, the product of the frequency of the 103-108 pulse waveforms by the number total port control lines 72-77, also the total number of LED strings in the light source 30) of 48 kHz on the display 14.
    [0059] [00059] Returning to Figure 5, if the sequencer 62, selects the port control line 72, the PWM signal received from the path 64 (which can be delayed through the delay circuit 88) can be transmitted along the line from port 72 to port 78. Since the PWM signal is an oscillating signal that fluctuates between no voltage and a high voltage (Vdc), port 78 will be activated and deactivated in conjunction with the PWM signal pulses. As will be discussed in more detail below, the alternate activation and deactivation of port 78 will cause an LED chain (for example, LED chain 110) to be activated and deactivated in a mode synchronized with port 78. That is, as port 78 is activated, the current can flow along the current path 84.
    [0060] [00060] This current can be supplied by the power source 56 and can pass through, for example, the LED chain 110. Furthermore, to ensure that the current flows only in one direction of the power source 56, through any given LED chain 110-115 and through port 78-83 selected, and for ground 86, diode 116 can be placed between power source 56 and LED chains 110-115. This diode can generally prevent current flow from the LED chains 110-115 back towards the power source 56. Furthermore, at least one inductor 118 can be placed in series with diode 116 in order to resist abrupt changes in current from the power source 56, thus operating to standardize the current transmitted to the LED chains 110-115, as well as providing an intensification functionality for a display backlight controller 14. That is, the input voltage can be increased in relation to the number of LEDs present on each LED chain 110-115 to properly polarize the LEDs. In addition, resistors can be present in Figure 5. These resistors can be illustrated as resistors 120A-120F. The 120A-120F resistors can, for example, represent the internal resistance of the various lines on which the 120A-120F resistors are illustrated. In another embodiment, specific resistance values can be selected for resistors 120A-120F as required to change the performance characteristics of, for example, display 14 (for example, for debugging).
    [0061] [00061] As the current passes from the power source 56 through diode 116 and, for example, to the LED chain 110 (when port 78 was activated), the current will cause the LEDs 122A-122C located on the chain 110 LEDs generate light. It should be noted that LEDs 122A122C can all be identical to LEDs 34 discussed above. In the present embodiment, three LEDs (for example, LEDs 122A-122C) can be placed in series as part of a respective LED chain (for example, LED chain 110); however, it should be noted that more or less than three LEDs, such as six LEDs, can be used in conjunction with a given LED chain (for example, the 110 LED chain).
    [0062] [00062] In operation, the activation and deactivation of the various ports 78-83 through a PWM signal transmitted along the control lines 72-77, can thus control the activation and deactivation of the LED chains 110-115. The activation and deactivation of LED chains 110-115 can, in turn, control the activation of LEDs 122A-127C on them. As such, sequencer 62 can, by providing the PWM signal for the various port control lines 72-77, control the operation of the various LED chains 110-115 in the light source 30.
    [0063] [00063] Furthermore, the sequencer 62 can actively select which of the 110-115 LED chains will generate light at a given time. As illustrated in flow chart 128 of Figure 8, sequencer 62 can receive a PWM signal generated by PWM 60 in step 130. In step 132, sequencer 62 can determine the sequence to be started. Step 132 may include determining the order of transmission of the PWM signal for port control lines 72-77, the use of delay circuit 88 to initiate a lag of the PWM signal received prior to transmission to the control lines of port 72-77, and / or other steps as required to control the light source 30.
    [0064] [00064] In step 134, the sequencer can determine whether the current level to be transmitted to the LED chains 110-115 should be reduced. As previously noted, the control of the brightness level of the display 14 can be adjusted by changing the duty cycle of the PWM signal together with an adjustment of the amount of current transmitted to the light source 30. This adjustment of the current transmitted to the LED chains 110-115, selected in the sequencing step 132, can occur when the brightness level of the display 14 must be adjusted below a threshold. For example, if the desired brightness of display 14 would otherwise require the duty cycle of the PWM signal to be less than, for example, 20%, then the duty cycle of the PWM signal can be adjusted to 20% and the current to be transmitted to the active LED chains 110-115 of the light source 30 can be reduced. This reduction can, for example, be adjusted by the display controller 58. If, however, the duty cycle of the PWM signal must be adjusted above a threshold level, for example, 20%, then the brightness level of the display 14 could be controlled by the duty cycle of the PWM signal without modifying the current that passes through the activated LED chains 110-115.
    [0065] [00065] Subsequent to step 134, sequencer 62, in step 136, can route the PWM signal (which can be lagged) to LED chains 110-115. This routing can be performed in a sequential mode. That is, the PWM signal can be sequentially transmitted to the port control line 72 for a given cycle of the PWM signal. Sequencer 62 can then transmit the PWM signal for a subsequent cycle to port control line 73. This procedure can continue in sequence for each port control line until sequencer 62 transmits a PWM signal to the control line. port control 77. Once the PWM signal has been transmitted to port control line 77, the sequencer can restart the process of transmitting the PWM signal to port control line 72. In this way, each of the LED chains 110-115 can be enabled sequentially. This sequential activation can be performed as previously discussed with respect to Figures 6 and 7, that is, with a lag. Additionally or alternatively, sequential activation can be performed without using the delay circuit 88, and without lag, as shown in Figures 9 and 10.
    [0066] [00066] Figure 9 illustrates a time sequence 138 that sequencer 62 can employ in one embodiment. Pulse waveform 140 may represent the PWM signal received by sequencer 62 from path 64. Pulse waveform 140 may have a frequency of at least approximately 1 kHz and a duty cycle of 100%. To activate the various LED chains 110-115, sequencer 62 can first transmit the PWM waveform 140 along port control line 72 as pulse waveform 141. Subsequently pulse waveform 140 can be transmitted to port control line 73 and so on until pulse waveform 140 is transmitted to port control line 77 as pulse waveform 146. Consequently, waveforms of pulse 141-146 can correspond to the pulses transmitted for each of the port control lines 72-77. Since each pulse is received on each of the ports 78-83 associated with the port control lines 72-77, the pulse can allow current to flow through the respective LED chain (for example, LED chain 110) thus generating light for use on display 14. It should be noted that in the illustrated mode the PWM 140 pulse waveform transmitted to each one of the breadth control lines rta 72-77 can have a 100% duty cycle. That is, at least one of the 110-115 LED chains is always activated.
    [0067] [00067] Figure 10 illustrates a time sequence 148 that sequencer 62 can employ in a modality whereby the PWM signal is in a 50% duty cycle. Pulse waveform 149 may represent the PWM signal received by sequencer 62 from path 64. Pulse waveform 149 may have a frequency of at least approximately 1 kHz and a duty cycle of 50%. To activate the various LED chains 110-115, sequencer 62 can first transmit the PWM waveform 149 along port control line 72 as pulse waveform 150. Subsequently, pulse waveform 149 can be transmitted to port control line 73 and so on until pulse waveform 149 is transmitted to port control line 77 as pulse waveform 155. Consequently, waveforms of pulse 150-155 can correspond to the pulses transmitted for each of the 72-77 port control lines. As each pulse is received at each of ports 78-83 associated with port control lines 72-77, the pulse can allow current to flow through the respective LED chain (for example, LED chain 110) thus generating light for use on the display 14. It should be noted that in the illustrated mode the PWM 149 pulse waveform transmitted to each of the port control lines 72-77 can have a duty cycle of 50%. Thus, each of the 150-155 pulse waveforms has a time interval 156 in which none of the LED chains 110-115 is active. Furthermore, each of the time intervals 156 can be equivalent to the time the voltage is triggered for ports 78-83, activating each of the 110-115 LED chains. Thus, taken as a whole, the light source 30 may be transmitting light in a 50% duty cycle. This can, for example, cause the display 14 to be at 50% of the luminosity as generated by the time sequence 138 (which, in turn, is darker than that provided by the time sequences 90 and 100, above ).
    [0068] [00068] Consequently, the pulse waveforms 93-98, 103-108, 141-146, and 150-155 can correspond to the pulses transmitted to each of the 72-77 port control lines, depending on the frequency and the desired duty cycle of display 14. Furthermore, in one embodiment, the amount that the duty cycle of the PWM signal is varied can directly correspond to the amount that the display 14 is darkened. That is, it is anticipated that the duty cycle of the PWM signals transmitted along path 64 can be varied from 0-100%. In addition, as discussed above, sequencer 62 can sequentially rotate the pulses received from the PWM signal between port control lines 72-77 at a high frequency, for example, at an effective rate of 48 kHz in order to minimize distortion and artifacts on the display 14.
    [0069] [00069] In one embodiment, the sequencer 62 can activate each of the 110-115 LED chains at a high frequency. The activation of the 110-115 LED chains at a high frequency can be beneficial since the artifacts that could typically be seen from using only one LED chain (for example, the 110 LED chain) can be reduced if the chains of LEDs LED 110-115 are activated and deactivated at a high rate. In one embodiment, each of the 110-115 LED chains can be selected by sequencer 62 at a rate of approximately 8 kHz. Thus, in the mode where six LED chains 110-115 are used, with a lag as shown in each of Figures 6 and 7, the effective frequency for display 14 would be 48 kHz (that is, the product of the selection frequency of each of the LED chains 110-115 by the sequencer 62 and the total number of LED chains 110-115). In another embodiment, each of the 110-115 LED chains can be selected by sequencer 62 at a higher or lower rate, such as a rate of approximately at least 1 kHz, 2 kHz, 3 kHz, 4 kHz, 5 kHz, 6 kHz, 7 kHz, 8 kHz, 9 kHz, or 10 kHz. This can lead to an effective rate of approximately at least 6 kHz, 12 kHz, 18 kHz, 24 kHz, 30 kHz, 36 kHz, 42 kHz, 48 kHz, 54 kHz, or 60 kHz. Regardless of the frequency selected by the sequencer 62 through the use of high frequency activation and deactivation, as well as through the use of a PWM signal and / or through the lag of the PWM signal to activate the LED chains 110-115, a large dimming range for display 14 as well as the removal of visual artifacts on display 14 can be concurrently performed.
    [0070] [00070] Figure 11 illustrates a front view of display 14 in which the duty cycle of a lagged PWM signal is applied to port control lines 74 and 75, causing LED chains 112 and 113 to activate. As illustrated , display 14 includes LCD panel 22 and light source 30. Light source 30 includes LEDs 122A-127C, which can be arranged in LED chains 110-115. Display 14 is shown, for example, as the outdated PWM signal is being transmitted to port control lines 74 and 75, thus activating ports 80 and 81. As ports 80 and 81 are activated, the current is free to pass through LED chains 112 and 113, which in turn activates LEDs 124A-124C and 125A-125C. Consequently, light can be generated by LEDs 124A-125C, resulting in light transmitted to LCD panel 22. This transmitted light is represented by light cones 158. As illustrated, these light cones 158 can overlap in such a way that reduce optical beat or other artifacts. That is, the overlapping of the light cones 158 generated by the LEDs 112A-127C allows a more complete coverage of the display 14. This overlap, together with the high frequency of effective PWM dimming (ie equal to the product of the PWM frequency base times the number of lagged LED chains), it can reduce the optical beat (or other artifacts) that might otherwise occur as a result of interference between the dimming frequency and the display regeneration frequency, for example.
    [0071] [00071] In a lag mode, as pulse waveform 95 is being transmitted to port control line 74, port 80 is activated. As port 80 is activated, the current is free to pass through LED chain 112, which in turn activates LEDs 124A-124C. Consequently, light can be generated by LEDs 124A-124C, resulting in the light transmitted to the LCD panel 22. This can be illustrated in Figure 12, which shows a top view of the light source 30. As illustrated in Figure 12 , LEDs 124A124C are activated as pulse waveform 96 becomes high. However, as can be seen in Figure 6, as pulse waveform 95 becomes high, pulse waveforms 93 and 94 are also high. Consequently, each of the LEDs 122A-122C and 123A-123C can be active as the pulse waveform 95 becomes high.
    [0072] [00072] In addition, Figure 13 shows a top view of the light source 30 as pulse waveform 95 is about to transition from high to low. As shown in Figure 13, LEDs 124A-124C are active as pulse waveform 95 is about to transition from high to low. However, as can be seen in Figure 6, as pulse waveform 95 approaches its transition downward, pulse waveforms 96 and 99 remain high. Consequently, each of the LEDs 125A-125C and 126A-126C can be active as pulse waveform 95 approaches the high to low transition. Thus, Figures 12 and 13 taken together, illustrate the lag activation of LED chains 110, 111, 113, and 114 as LED chain 112 is sequentially activated and deactivated.
    [0073] [00073] The specific modalities described above have been shown as an example, and it should be understood that these modalities may be susceptible to various modifications and alternative forms. It should be further understood that the embodiments are not intended to be limited to the specific forms described, but rather to cover all modifications, equivalents, and alternatives that fall within the spirit and scope of this description.
    权利要求:
    Claims (19)
    [0001]
    Electronic device (10) comprising: a display panel (14) comprising a plurality of pixels; a light source (30) comprising a plurality of light emitting diode, LED chains, adapted to generate light to illuminate the plurality of pixels; a sequencer (62) configured to receive a PWM signal and to phase the PWM signal to create an effective frequency for controlling the LED chains, in which an amount of lag applied to each LED chain based on a number of chains LED, and where a pulse of a first LED chain of the plurality of LED chains overlaps at least one pulse of a different LED chain from the plurality of LED chains; and a display control logic (58) adapted to activate and deactivate each LED chain of the plurality of LED chains at the effective frequency of at least 1 kHz, where the effective frequency is greater than a PWM frequency (60), characterized by the fact that each LED of the plurality of LED chains produces a light cone (158) that overlaps light cones (158) of other LEDs of the plurality of LED chains, and in which the light cones (158) that are overlap and the higher effective frequency reduces or eliminates optical beats or other artifacts that result from interference between the frequency of the pulse width modulation signal and a regeneration frequency of the display panel (14).
    [0002]
    Electronic device (10), according to claim 1, characterized by the fact that it comprises a pulse width modulator, PWM (60), configured to generate a pulsed signal and transmit the pulsed signal to the display control logic ( 58).
    [0003]
    Electronic device (10), according to claim 2, characterized by the fact that the display control logic (58) is adapted to receive the pulsed signal and use the pulsed signal to sequentially activate and deactivate the plurality of LED chains .
    [0004]
    Electronic device (10), according to claim 1, characterized by the fact that the display control logic (58) is adapted to sequentially activate and deactivate each LED chain at a frequency of at least 8 kHz.
    [0005]
    Electronic device (10) comprising: a pulse width modulator, PWM (60), adapted to generate an oscillating PWM signal at a frequency of at least 1 kHz and at least at a 10-bit brightness resolution; and a sequencer (62) adapted to receive the oscillating PWM signal and phase the oscillating PWM signal to control an activation and deactivation of at least one light emitting diode (LED) chain, of a plurality of LED chains, in that each of the light emitting diode chains is activated and deactivated sequentially, where an amount of lag applied to each LED chain is based on a number of LED chains, and where a pulse from a first LED chain the plurality of LED chains overlaps at least one pulse of a different LED chain from the plurality of LED chains, characterized by the fact that each LED of the plurality of LED chains produces a light cone (158) which overlaps light cones (158) of other LEDs of the plurality of LED chains, and in which the overlapping light cones (158) and the higher effective frequency reduces or eliminates optical beats or other artifacts that result from interference between the frequency of the mod signal pulse width adjustment and a regeneration frequency of the display panel (14).
    [0006]
    Electronic device (10), according to claim 5, characterized by the fact that it comprises a display (14), in which the brightness of the display (14) is controlled by adjusting a duty cycle of the oscillating PWM signal.
    [0007]
    Electronic device (10), according to claim 5, characterized by the fact that the sequencer (62) defaults the oscillating PWM signal to generate an effective frequency of at least 6 kHz.
    [0008]
    Electronic device (10), according to claim 5, characterized by the fact that the sequencer (62) defaults the oscillating PWM signal to generate an effective frequency of at least 48 kHz.
    [0009]
    Electronic device (10) comprising: a display (14) having a plurality of light emitting diode, LED chains, adapted to generate light to illuminate a plurality of pixels on the display (14); a pulse width modulator, PWM (60), adapted to generate an oscillating PWM signal; and a display control logic (58) adapted to activate and deactivate the plurality of LED chains sequentially at least 1 kHz, where the display control logic (58) comprises a delay circuit (88) adapted to lag the oscillating PWM signal for activating and deactivating the LEDs at an effective frequency of 10 kHz, in which an amount of lag applied to each LED chain is based on a number of LED chains, and in which a pulse from a first chain of LEDs LED of the plurality of LED chains overlaps at least one pulse of an LED chain different from the plurality of LED chains, where the effective frequency is greater than the frequency of the PWM (60), characterized by the fact that each LED of the plurality of LED chains produces a light cone (158) that overlays light cones (158) of other LEDs of the plurality of LED chains, and in which the overlapping light cones (158) and the higher effective frequency reduces or eliminates optical beats or other art effects that result from interference between the frequency of the pulse width modulation signal and a regeneration frequency of the display panel (14).
    [0010]
    Electronic device (10) according to claim 9, characterized by the fact that each of the LED chains comprises a plurality of LEDs.
    [0011]
    Electronic device (10), according to claim 10, characterized by the fact that the display control logic (58) is adapted to activate and deactivate the plurality of LED chains in at least 8 kHz.
    [0012]
    Electronic device (10), according to claim 9, characterized by the fact that the PWM (60) modifies a duty cycle of the oscillating PWM signal to control the display brightness (14).
    [0013]
    Electronic device (10), according to claim 9, characterized by the fact that the display control logic (58) comprises a delay circuit (88) adapted to delay the oscillating PWM signal for activating and deactivating the LEDs in an effective frequency of at least 48 kHz.
    [0014]
    Method for providing lighting for a display (14) to reduce visual artifacts, comprising the steps of: generate a pulse width modulator signal, PWM, oscillating in a PWM (60); receiving the PWM signal on a sequencer (62); and phase and sequentially route the PWM signal from the sequencer (62) to a plurality of light emitting diode (LED) chains on a display (14) to activate and deactivate the LED chains at an effective frequency of at least 6 kHz to reduce the optical beat resulting from the frequency of the PWM signal and a regeneration frequency of the display (14), in which an amount of lag applied to each LED chain is based on a number of LED chains, and on that a pulse of a first LED chain of the plurality of LED chains overlaps at least one pulse of an LED chain different from the plurality of LED chains, where the effective frequency is greater than the frequency of the PWM (60), characterized by the fact that each LED of the plurality of LED chains produces a light cone (158) that overlaps light cones (158) of other LEDs of the plurality of LED chains, and in which the light cones (158) that are overlap and an effective frequency of at least 6 kHz red uz or eliminates optical beats or other artifacts that result from interference between the frequency of the pulse width modulation signal and a regeneration frequency of the display panel (14).
    [0015]
    Method according to claim 14, characterized by the fact that it comprises adjusting the brightness of the display (14) by adjusting the duty cycle of the PWM signal.
    [0016]
    Method according to claim 15, characterized by the fact that it comprises adjusting the duty cycle of the PWM signal based on user input or based on a determination of the amount of internal energy remaining in a power source (56) internal.
    [0017]
    Method for illuminating a display (14), comprising the steps of: generate a light from a light source (30); directing the light towards a plurality of pixels on a display (14); and switching light-emitting diode (LED) chains, LED, from the light source (30) by turning on and off in sequence at an effective frequency of at least 48 kHz via a lagged pulse width modulator signal, PWM, in which an amount of lag applied to each LED chain is based on a number of LED chains, and in which a pulse of a first LED chain of the plurality of LED chains overlaps at least one pulse of a different LED chain from the plurality of chains LEDs, where the effective frequency is greater than the PWM frequency (60), characterized by the fact that each LED of the plurality of LED chains produces a light cone (158) that overlaps light cones (158) of others LEDs of the plurality of LED chains, and in which the overlapping light cones (158) and an effective frequency of at least 48 kHz reduces or eliminates optical beats or other artifacts that result from interference between the frequency of the modulation signal. pulse width and a frequency regeneration rate of the display panel (14).
    [0018]
    Method, according to claim 17, characterized by the fact that it comprises adjusting a duty cycle of the PWM signal in response to changes initiated by the user of the display brightness (14).
    [0019]
    Method according to claim 17, characterized by the fact that switching the light source (30) on and off comprises sequentially activating and deactivating at least one light emitting diode, LED, chain in the light source (30) .
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    法律状态:
    2019-01-08| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-08-06| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-08-04| B07A| Application suspended after technical examination (opinion) [chapter 7.1 patent gazette]|
    2021-02-23| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-04-06| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 10 (DEZ) ANOS CONTADOS A PARTIR DE 06/04/2021, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US12/683,414|2010-01-06|
    US12/683,414|US8907884B2|2010-01-06|2010-01-06|LED backlight system|
    PCT/US2010/047311|WO2011084188A1|2010-01-06|2010-08-31|Led backlight system|
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