PATENT DOCUMENT

Publication Number: US-9785007-B2
Application Number: US-201414249237-A
Country: US
Kind Code: B2

Title: Display with localized backlight dimming

Abstract:
A display may have an array of display pixels for displaying images for a user. A backlight unit may provide backlight for the display pixels. The backlight unit may have a substrate such as a printed circuit substrate. An array of locally dimmable backlight elements may be mounted on the substrate. The substrate may be mounted against an inner surface of a metal electronic device housing or other support structure in an electronic device. Each backlight element may have a semiconductor package containing a semiconductor die. The semiconductor die may have a light-emitting diode and a light-emitting-diode control circuit. The light-emitting-diode control circuit may have a pair of transistors and a capacitor. One of the transistors may be connected in series with the light-emitting diode. The light-emitting diode control circuit may receive control signals on a gate line terminal and a source line terminal.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 an array of display pixels; and 
 a backlight that provides backlight illumination for the array of display pixels, wherein the backlight comprises an array of backlight elements, wherein each backlight element includes a light-emitting diode and a light-emitting-diode control circuit that controls how much backlight is emitted by the light-emitting diode, wherein each light-emitting diode in the backlight is independently controlled by a respective one of the light-emitting-diode control circuits, wherein each backlight element has a plastic semiconductor package, wherein the light-emitting-diode control circuit of each backlight element comprises first and second transistors and a capacitor coupled between the first and second transistors, and wherein the first and second transistors, the capacitor, and the light-emitting diode of each backlight element are part of a common semiconductor die that is packaged in the plastic semiconductor package. 
 
     
     
       2. The display defined in  claim 1  wherein the light-emitting diode of each backlight element is connected in series with the second transistor of that backlight element. 
     
     
       3. The display defined in  claim 1  wherein the plastic semiconductor package for each backlight element also contains the light-emitting diode of another one of the backlight elements. 
     
     
       4. The display defined in  claim 1  wherein the plastic semiconductor package for each of the backlight elements contains four of the backlight elements. 
     
     
       5. The display defined in  claim 1  further comprising a substrate on which the array of backlight elements is mounted. 
     
     
       6. The display defined in  claim 5  further comprising metal structures, wherein the substrate is mounted on the metal structures to dissipate heat from the backlight elements through the metal structures. 
     
     
       7. The display defined in  claim 6  wherein the metal structures comprise electronic device housing structures. 
     
     
       8. The display defined in  claim 6  wherein the array of display pixels comprises an array of liquid crystal display pixels. 
     
     
       9. An electronic device, comprising:
 an electronic device housing; 
 display layers that display images; and 
 a backlight with an array of locally dimmed backlight elements that provide backlight illumination for the display layers, each backlight element including a light-emitting diode and a light-emitting-diode control circuit, wherein each light-emitting diode in the backlight is independently controlled by a respective one of the light-emitting-diode control circuits, wherein the light-emitting-diode control circuit comprises first and second transistors and a capacitor coupled between the first and second transistors, wherein the light-emitting diode, the first transistor, the second transistor, and the capacitor of each backlight element are formed as part of a common semiconductor die. 
 
     
     
       10. The electronic device defined in  claim 9  wherein the backlight is mounted on an interior surface of the electronic device housing and wherein the electronic device housing comprises metal. 
     
     
       11. A display, comprising:
 liquid crystal display layers that display images; and 
 a backlight unit with an array of locally dimmed backlight elements that provide backlight for the liquid crystal display layers, each backlight element including a light-emitting diode and a light-emitting-diode control circuit, wherein the light-emitting-diode control circuit comprises first and second transistors and a capacitor coupled between the first and second transistors, wherein the light-emitting diode, the first transistor, the second transistor, and the capacitor are formed as part of a common semiconductor die in a plastic semiconductor package, and wherein each light-emitting diode in the backlight is independently controlled by a respective one of the light-emitting-diode control circuits. 
 
     
     
       12. The display defined in  claim 11  wherein the light-emitting-diode control circuit of each backlight element receives control signals from a gate line and a source line.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with displays. 
     Electronic devices often include displays. For example, cellular telephones and computers have displays. 
     Displays such as liquid crystal displays have arrays of display pixels. Display driver circuitry is used to display images on a display by loading image data into an array of display pixels. To enhance visibility of the images on a display, the display may be provided with a backlight unit. The backlight unit emits backlight that passes through the array of display pixels and illuminates the images that are being displayed. 
     The dynamic range of a display may be enhanced by using a backlight unit that is capable of localized dimming. This type of backlight unit has an array of light-emitting diodes spread across the display. In portions of the display in which bright image content is being displayed, the light-emitting diodes are driven and supply backlight. In portions of the display in which black image content is being displayed, the light-emitting diodes can be turned off to ensure that the display appears completely black. 
     It can be challenging to implement a backlight unit with local dimming capabilities in a display. If care is not taken, the circuitry used to drive the array of light-emitting diodes can be overly complex. Drive circuit complexity can be reduced by using fewer light-emitting diodes in the display, but the lowered backlight resolution that results from this type of approach can give rise to undesired visible artifacts such as halos around bright portions of an image that are set against dark backgrounds. 
     It would therefore be desirable to be able to provide improved backlighting for a display. 
     SUMMARY 
     A display may be provided with liquid crystal display layers. The display layers may have an array of display pixels for displaying images for a user. 
     A backlight unit may provide backlight for the display layers. The backlight unit may have a substrate such as a printed circuit substrate. An array of locally dimmable backlight elements may be mounted on the substrate. The substrate may be mounted against an inner surface of a metal electronic device housing or other support structure in an electronic device. 
     Each backlight element in the array of backlight elements may have a semiconductor package containing a semiconductor die. The semiconductor die may include a light-emitting diode and a light-emitting diode control circuit. The light-emitting diode control circuit may have a pair of transistors and a capacitor coupled between the transistors. One of the transistors may be connected in series with the light-emitting diode and may serve as a voltage controlled current source. The other transistor may serve to control the application of control signals to the voltage controlled current source transistor. The light-emitting diode control circuit may receive control signals on a gate line terminal and a source line terminal. 
     If desired, the light-emitting diode of each backlight element may be provided as a discrete device and the light-emitting diode control circuitry of that backlight element may be implemented using a semiconductor die that is separate from the discrete device. Arrangements in which two or four backlight elements are mounted in a common semiconductor package may also be used. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer with a display in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device with a display in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer with a display in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative electronic device such as a display for a computer or other electronic device in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an illustrative display in accordance with an embodiment. 
         FIG. 6  is a circuit diagram of an illustrative backlight unit having an array of light-emitting diodes in accordance with an embodiment. 
         FIG. 7  is a circuit diagram of an illustrative light-emitting diode circuit that may be used in implementing a backlight element in an array of backlight elements for a backlight unit in accordance with an embodiment. 
         FIG. 8  is a perspective view of an illustrative packaged integrated circuit die containing a light-emitting diode and drive circuitry of the type shown in  FIG. 7  in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative display having a backlight formed from backlight elements mounted on a printed circuit substrate supported by an interior surface of an electronic device housing in accordance with an embodiment. 
         FIG. 10  is a diagram of an illustrative semiconductor package that contains two circuits of the type shown in  FIG. 7  in accordance with an embodiment. 
         FIG. 11  is a diagram of an illustrative semiconductor package that contains four circuits of the type shown in  FIG. 7  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with displays such as liquid crystal displays. A backlight unit (sometimes referred to as a backlight) can be used to provide backlight illumination to a liquid crystal display. The dynamic range of the display can be enhanced by using a backlight unit that supports localized dimming. Illustrative electronic devices of the types that may be provided with a backlight unit that supports localized dimming are shown in  FIGS. 1, 2, 3, and 4 . 
     Electronic device  10  of  FIG. 1  has the shape of a laptop computer and has upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  has hinge structures  20  (sometimes referred to as a clutch barrel) to allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  is mounted in housing  12 A. Upper housing  12 A, which may sometimes be referred to as a display housing or lid, is placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows an illustrative configuration for electronic device  10  based on a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device  10 , housing  12  has opposing front and rear surfaces. Display  14  is mounted on a front face of housing  12 . Display  14  may have an exterior layer that includes openings for components such as button  26  and speaker port  28 . Device  10  may, if desired, be a compact device such as a wrist-mounted device or pendant device (as examples). 
     In the example of  FIG. 3 , electronic device  10  is a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  has opposing planar front and rear surfaces. Display  14  is mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  has an opening to accommodate button  26 . 
       FIG. 4  shows an illustrative configuration for electronic device  10  in which device  10  is a computer display, a computer that has an integrated computer display, a stand-alone display for other equipment, or other electronic device that includes a display. Display  14  is mounted on a front face of housing  12 . With this type of arrangement, housing  12  for device  10  may be mounted on a wall or may have an optional structure such as support stand  30  to support device  10  on a flat surface such as a tabletop or desk. 
     Display  14  may be a liquid crystal display or a display that includes display structures formed using other display technologies. A cross-sectional side view of an illustrative configuration for display  14  of device  10  (e.g., a liquid crystal display for the devices of  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4  or other suitable electronic devices) is shown in  FIG. 5 . As shown in  FIG. 5 , display  14  may include display layers  46  that include an array of display pixels P for displaying images for a user and may include backlight structures such as backlight unit  42  for producing backlight  44 . During operation, backlight  44  travels outwards (vertically upwards in dimension Z in the orientation of  FIG. 5 ) and passes through the array of display pixels P in display layers  46 . This illuminates any images that are being produced by the array of display pixels for viewing by a user. For example, backlight  44  may illuminate images on display layers  46  that are being viewed by viewer  48  in direction  50 . 
     Display layers  46  may be mounted in chassis structures such as a plastic chassis structure and/or a metal chassis structure to form a display module for mounting in housing  12  or display layers  46  may be mounted directly in housing  12  (e.g., by stacking display layers  46  into a recessed portion in housing  12 ). 
     Display layers  46  may include a liquid crystal layer such a liquid crystal layer  52 . Liquid crystal layer  52  may be sandwiched between display layers such as display layers  58  and  56 . Layers  56  and  58  may be interposed between lower (innermost) polarizer layer  60  and upper (outermost) polarizer layer  54 . 
     Layers  58  and  56  may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers  56  and  58  may be layers such as a thin-film transistor layer and/or a color filter layer. Conductive traces, color filter elements, transistors, and other circuits and structures may be formed on the substrates of layers  58  and  56  (e.g., to form a thin-film transistor layer and/or a color filter layer). Touch sensor electrodes may also be incorporated into layers such as layers  58  and  56  and/or touch sensor electrodes may be formed on other substrates. 
     With one illustrative configuration, layer  58  may be a thin-film transistor layer that includes an array of thin-film transistors and associated electrodes (display pixel electrodes) for applying electric fields to liquid crystal layer  52  and thereby displaying images on display  14 . Layer  56  may be a color filter layer that includes an array of color filter elements for providing display  14  with the ability to display color images. If desired, layer  58  may be a color filter layer and layer  56  may be a thin-film transistor layer. 
     During operation of display  14  in device  10 , control circuitry (e.g., one or more integrated circuits on a printed circuit such as integrated circuits  68  on printed circuit  64 ) may be used to generate information to be displayed on display  14  (e.g., display data). The information to be displayed may be conveyed to display driver circuitry  62  using signal path  64 . Display driver circuitry  62  may include one or more integrated circuits such as column driver integrated circuits for driving data signals onto corresponding data lines in display  14 , gate driver circuitry for supplying gate signals to gate lines in display  14 , and a timing controller (TCON) integrated circuit that supplies image data to the column drivers and gate driver controls signals to the gate driver circuitry. Display driver circuitry  62  may also include circuitry for controlling the application of backlight control signals to backlight unit  42 . If desired, display driver circuitry for the display pixels of display  14  may be implemented using thin-film transistor circuitry (e.g., gate drivers or other driver circuitry on a thin-film transistor layer, etc.). 
     Backlight unit  42  may include a substrate such as a printed circuit substrate. An array of backlight elements may be mounted on the substrate. The backlight elements include light-emitting diodes and light-emitting-diode control circuits for controlling operation of the light-emitting diodes. Light from the light-emitting diodes may serve as backlight  44  for display  14 . The intensity of the light emitted from each of the light-emitting diodes is preferably individually controllable to implement localized backlight dimming for display  14 . 
     Optical films  70  may be interposed between backlight unit  42  and display layers  46  and/or may be incorporated elsewhere in display  14 . Optical films  70  may include diffuser layers for helping to homogenize backlight  44  and thereby reduce hotspots, compensation films for enhancing off-axis viewing, and brightness enhancement films (also sometimes referred to as turning films) for collimating backlight  44 . Optical films  70  may overlap the structures in backlight unit  42 . In configurations in which display layers  46  have a rectangular footprint in the X-Y plane of  FIG. 5 , optical films  70  and backlight unit  42  may have a matching rectangular footprint. 
     Display  14  may have an array of display pixels (e.g., a rectangular array having rows and columns) for displaying images to a viewer. Vertical signal lines called data lines may be used to carry display data to respective columns of display pixels. Horizontal signal lines called gate lines may be used to carry gate line signals (sometimes referred to as gate control signals or gate signals) to respective rows of display pixels. 
     The display pixels in display  14  may have a density of about 50-300 pixels per inch or other suitable density (e.g., a density above or below  100  pixels per inch). Backlight unit  42  preferably has individually adjustable backlight elements arranged in an array with a lower density than the array of display pixels in display  14 . For example, there may be 500,000 or more, 5 million or more, or 50 million or more display pixels in display  14 , whereas a backlight unit with the same footprint may contain one tenth of this number of backlight elements in the array of backlight elements in backlight unit  42  (or fewer than one tenth), one hundredth or fewer backlight elements, or one thousandth or fewer backlight elements in the backlight unit of display  14 . 
     The display pixels of layers  46  in a liquid crystal display generally exhibit a limited dynamic range (i.e., the black-to-white ratio of the display pixels in display  14  is not zero). To enhance the dynamic range of display  14 , the backlight elements in backlight unit  42  may be individually controlled (i.e., backlight unit  42  may use a localized dimming scheme). With this type of approach, some light-emitting diodes in backlight unit  42  are turned on and supply backlight to portions of display  14  in which bright image content is being displayed, whereas other light-emitting diodes in backlight unit  42  are turned off to ensure that black image content can be displayed properly (i.e., to ensure the sufficiently dark black levels are achieved). 
     To avoid overwhelming the control circuitry for the backlight unit, an array of actively driven backlight elements can be used in backlight unit  42 . Each actively driven backlight element includes a light-emitting component such as a light-emitting diode and integrated control circuitry for controlling the light-emitting component. 
     This type of arrangement is shown in  FIG. 6 . As shown in  FIG. 6 , backlight unit  42  may include an array of backlight elements such as backlight elements  94 . Backlight elements  94  may be organized in rows and columns and may be mounted on a substrate such as substrate  80 . Substrate  80  may be a rigid printed circuit board (e.g., a printed circuit formed from a material such as fiberglass-filled epoxy) or may be a flexible printed circuit (e.g., a printed circuit formed from a flexible polyimide layer or a substrate formed from a layer of other polymer material). Other mounting arrangements may be used for backlight elements  94  if desired. For example, backlight elements  94  may be mounted on the interior of a device housing and may be interconnected using wires or cables, backlight elements may be mounted on a plastic carrier, etc. 
     Backlight elements  94  may be based on integrated circuit die that include drive circuitry and light-emitting diode structures for emitting backlight  44 . Each backlight element drive circuit may be provided on the same die as the light-emitting diode that is being controlled by that circuit or may be provided on a separate die that is mounted in a common semiconductor package with the light-emitting diode. 
     During operation of display  14  in device  10 , backlight control information for backlight unit  42  may be generated by control circuitry  68  and/or other control circuits (e.g., backlight information may form part of the display data that is being used to control the array of display pixels in display layers  46  of display  14 ). The backlight information may specify the strength of the backlight illumination  44  to be produced by each of the backlight elements  94  in backlight unit  42 . 
     The backlight control information may be supplied to backlight control circuitry  82  in backlight unit  42  via path  84 . Backlight control circuitry  82  may include row driver circuitry for driving backlight gate line signals GL into the array of backlight elements  94  on gate lines  86  and may include column driver circuitry for driving backlight source line signals SL into the array of backlight elements  94  on source lines  88 . Power supply voltage VLED (e.g., a positive power supply voltage at a fixed voltage level) may be supplied to backlight elements  94  using power supply lines  90 . A ground power supply voltage may be supplied to backlight elements  94  on ground lines  92 . Backlight control circuitry  82  may be implemented in one or more display driver integrated circuits (e.g., a timing controller integrated circuit, a display column driver integrated circuit, other display driver integrated circuit(s)  62 , portions of circuits  68 , etc.). 
       FIG. 7  is a circuit diagram of an illustrative backlight element such as one of backlight elements  94  of backlight unit  42  of  FIG. 6 . As shown in  FIG. 7 , backlight element  94  may be a four terminal device that receives control signals on terminals  86  and  88  and power on terminals  90  and  92 . Backlight element  94  of  FIG. 7  includes light-emitting diode  96  for emitting backlight  44  and light-emitting diode control circuitry that controls the light-emitting diode  96  (i.e., transistors T 1 , T 2 , and capacitor C). 
     The amount of current that flows through light-emitting diode  96  of  FIG. 7  is controlled using transistors T 1  and T 2 . Transistor T 2 , which is connected in series with diode  96 , may serve as a voltage-controlled current source. Transistor T 1  may control the application of a controlling voltage signal from source line SL to the gate of transistor T 2 . Capacitor C serves as a data storage element that temporarily stores the backlight data that has been loaded into backlight element  94 . During operation of display  14 , control signals such as source line signal SL and gate line signal GL may be used to control transistors T 1  and T 2  and thereby control the amount of current flowing through light-emitting diode  96 . Light-emitting diode  96  and the other circuitry of element  94  may be integrated into a single semiconductor die or light-emitting diode  96  may be implemented as a discrete component while the remaining portion of circuitry  94  is implemented as a separate component (e.g., a separate integrated circuit semiconductor die mounted in a common semiconductor package). 
     With one illustrative embodiment, an analog control scheme is used to control the backlight elements. With analog control, gate line signal GL is asserted to turn on transistor T 1 . Turning on transistor T 1  applies the source line signal SL to the gate of drive transistor T 2 . Capacitor C temporarily stores source line signal SL. Source line signal SL serves as an analog control voltage. The magnitude of source line signal SL that is applied to the gate of transistor T 2  controls the magnitude of the drive current through light-emitting diode  96  gate voltage on transistor T 2 . The magnitude of the current flowing through light-emitting diode  96  controls that amount of backlight  44  that is emitted by light-emitting diode  96 . 
     With another illustrative embodiment, a digital pulse width modulation control scheme is used to control the backlight elements. With this approach, each frame of image data (e.g., each 1/60 th  of a second in a 60 Hz video stream) is divided into a set of subframes. There may be, for example, six subframes in each frame of image data being displayed on display  14 . Each subframe may have a different length. For example, the six subframes may have respective lengths proportional to 2 0 , 2 1 , 2 2 , 2 3 , 2 4 , and 2 5 . A gate line signal GL may be asserted at the beginning of each subframe. Source line signals SL in each column serve as digital control signals. The status of source line signal SL (high or low) when the gate line signal GL is asserted at the beginning of each subframe determines whether a given light-emitting diode  96  is turned on or off for the duration of that subframe. By controlling the states of source line signals SL during each frame, light-emitting diode  96  can be turned on for certain subframes and can be turned off for certain subframes, thereby controlling the overall duration for which light-emitting diode  96  is turned on in that frame. 
     If desired, the circuitry of each backlight element  94  may be packaged in a respective semiconductor package (e.g., a surface mount technology package or other suitable plastic package).  FIG. 8  is a perspective view of an illustrative packaging configuration that may be used for backlight element  94 . In the example of  FIG. 8 , backlight element  94  has plastic semiconductor package  106 . Package  106  may be formed from molded plastic and may have terminals such as metal terminals (contacts)  100 . Each of terminals  100  may be used for a respective one of the terminals of backlight element  94  of  FIG. 7 . A first of terminals  100  may be used for source line  88 , a second of terminals  100  may be coupled to gate line  86 , a third of terminals  100  may be coupled to power supply line  90 , and a fourth of terminals  100  may be coupled to ground  92 . In backlight element configurations that require more control lines, one or more additional terminals  100  may be provided. 
     Light-emitting diode  96  and the remaining components of backlight element  94  (e.g., transistor T 1 , transistor T 2 , and capacitor C) may be implemented on a single unitary integrated circuit die (see, e.g., semiconductor die  102 ) that is packaged within package  106 . If desired, light-emitting diode  96  may be implemented as a discrete semiconductor device (see, e.g., device  104 ) while the remaining components of backlight element  94  (e.g., light-emitting-diode control circuitry such as transistor T 1 , transistor T 2 , and capacitor C) may be implemented as a separate integrated circuit die (see, e.g., semiconductor die  102 ). Package  106  is preferably used to house all of the circuitry of backlight element  94 , but arrangements in which a portion of the circuitry of backlight element  94  such as the light-emitting-diode control circuit of that element is implemented in a first package and another portion of the circuitry of backlight element  94  is implemented in a second package that is mounted adjacent to the first package on substrate  80  may be used, if desired. 
     Packaged backlight elements such as backlight element  94  of  FIG. 8  may be mounted in an array of rows and columns on printed circuit substrate  80  ( FIG. 6 ). To enhance heat removal, it may be desirable to mount printed circuit substrate  80  on a heat sink. With one illustrative configuration, backlight elements  94  are mounted on printed circuit substrate  80  and printed circuit substrate  80  is mounted against an interior surface of housing  12 , as shown in  FIG. 9 . In this type of arrangement, housing  12  may be formed from a material that helps dissipate heat such as aluminum or other metal. A layer of adhesive may be used to attach substrate  80  to housing  12  or other attachment mechanisms may be used (e.g., screws or other fasteners, etc.). Other heat sinking arrangements may be used to dissipate heat from backlight elements  94  if desired. The arrangement of  FIG. 9  in which backlight elements are mounted against housing  12  is merely illustrative. 
     As shown in  FIG. 10 , two separate backlight elements may be packaged in a common package. In the  FIG. 10  example, first backlight element  94 A and second backlight element  94 B are mounted in a common semiconductor package such as package  106  (e.g., a surface mount technology package formed form molded plastic or other suitable electronic component package). First backlight element  94 A may include a light-emitting diode  96  that is implemented on the same integrated circuit die (i.e., semiconductor die  102 A) as the light-emitting-diode control circuit formed from transistors T 1  and T 2  and capacitor C for backlight element  94 A or may be implemented using two separate die. Similarly, second backlight element  94 B may include a light-emitting diode  96  that is implemented on the same integrated circuit die (i.e., semiconductor die  102 B) as the light-emitting-diode control circuit formed from transistors T 1  and T 2  and capacitor C for backlight element  94 B or may be implemented using two separate die. 
     If desired, four backlight elements may be packaged in a common package. As shown in  FIG. 11 , for example, backlight element  94 - 1 , backlight element  94 - 2 , backlight element  94 - 3 , and backlight element  94 - 4  may be packaged in a common semiconductor package such as package  106 . First backlight element  94 - 1  may include a light-emitting diode  96  that is implemented on the same integrated circuit die (i.e., semiconductor die  102 - 1 ) as the light-emitting-diode control circuit formed from transistors T 1  and T 2  and capacitor C for backlight element  94 - 1  or may be implemented using two separate die. Second backlight element  94 - 2  may include a light-emitting diode  96  that is implemented on the same integrated circuit die (i.e., semiconductor die  102 - 2 ) as the light-emitting-diode control circuit formed from transistors T 1  and T 2  and capacitor C for backlight element  94 - 2  or may be implemented using two separate die. Third backlight element  94 - 3  may include a light-emitting diode  96  that is implemented on the same integrated circuit die (i.e., semiconductor die  102 - 3 ) as the light-emitting-diode control circuit formed from transistors T 1  and T 2  and capacitor C for backlight element  94 - 3  or may be implemented using two separate die. Fourth backlight element  94 - 4  may include a light-emitting diode  96  that is implemented on the same integrated circuit die (i.e., semiconductor die  102 - 4 ) as the light-emitting-diode control circuit formed from transistors T 1  and T 2  and capacitor C for backlight element  94 - 4  or may be implemented using two separate die. 
     To accommodate additional control signals, packages  106  of  FIGS. 10 and 11  may be provided with additional terminals  100  (e.g., additional source line and/or gate line terminals). If, for example, package  106  of  FIG. 10  is shared between two columns in backlight unit  42 , an additional terminal  100  may be included in package  106  to accommodate an additional source line. The first source line in this scenario is used to control backlight element  94 A in a first column of backlight elements in the backlight element array and the second source line is used to control backlight element  94 B in an adjacent second column of backlight elements in the backlight element array. The gate line GL can be shared between elements  94 A and  94 B. If desired, source lines can be shared and other arrangements can be used for interconnecting the control lines of the backlight array to the terminals of backlight elements  94 . 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20140409
Publication Date: 20171010
Grant Date: 20171010
Priority Date: 20140409
Inventors: KIM BYOUNGSUK
QI JUN
YIN VICTOR H.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05B45/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3426", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133603", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0686", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3426", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B45/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0686", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133603", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133603", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0686", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05B33/086", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3426", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2001/133612", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F2001/133601", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133601", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133612", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133601", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133612", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 54266285