Patent Grant
11217153
This disclosure relates generally to light emitting diodes (LEDs) and LED driver circuitry for a display, and more specifically to a display architecture with distributed driver circuits.
LEDs are used in many electronic display devices, such as televisions, computer monitors, laptop computers, tablets, smartphones, projection systems, and head-mounted devices. Modern displays may include well over ten million individual LEDs that may be arranged in rows and columns in a display area. In order to drive each LED, current methods employ driver circuitry that requires significant amounts of external chip area that impacts the size of the display device.
In a first aspect, a display device comprises an array of light emitting diode zones, a control circuit, a group of driver circuits distributed in the display area of the display device, a readback line, and a multi-wire shared command interface. The one or more light emitting diodes generate light in response to respective driver currents. The control circuit generates driver control signals and command signals. The group of driver circuits each drive a respective light emitting diode zone by controlling the respective driver currents in response to the driver control signals. The driver circuits furthermore generate readback data to the control circuit responsive to the command signals. The readback line communicates the readback data from the group of driver circuits to the control circuit. The multi-wire shared command interface is coupled between the control circuit and each of the driver circuits in the group of driver circuits and provides the driver control signals to the group of driver circuits.
In another aspect, a driver circuit for a display device includes control logic, and a set of pins including at least one LED driving output pin, a data input pin, a serial data output pin, a multi-pin command interface, a power pin, and a ground pin. The control logic operates in at least an addressing mode and an operational mode. In the operational mode, the control logic obtains a driver control signal and controls a driver current to an LED zone based on the driver control signal. The control logic further receives commands and outputs readback data responsive to the commands. In the addressing mode, the control logic obtains an incoming addressing signal, stores an address for the driver circuit based on the incoming addressing signal, and generates an outgoing addressing signal based on the incoming addressing signal. The LED driving output pin sinks the driver current during the operational mode. The data input pin receives the incoming addressing signal during the addressing mode and facilitates communication of the readback data via a serial communication chain during the operational mode. The serial data output pin outputs the outgoing addressing signal during the addressing mode and facilitates communication of the readback data via the serial communication chain during the operational mode. The multi-pin command interface receives the driver control signals from a control circuit via a multi-wire shared command interface. The power pin provides a supply voltage to the driver circuit and the ground pin to provide a path to ground.
In another aspect, a driver circuit for a display device includes control logic, at least one LED driving output pin, a data input pin, a serial data output pin, a parallel data output pin, a multi-pin command interface, a power pin, and a ground pin. The control logic operates in at least an addressing mode and an operational mode. In the operational mode, the control logic obtains a driver control signal and controls a driver current to an LED zone based on the driver control signal. The control logic further receives commands and outputs readback data responsive to the commands. In the addressing mode, the control logic obtains an incoming addressing signal, stores an address for the driver circuit based on the incoming addressing signal, and generates an outgoing addressing signal based on the incoming addressing signal. The LED driving output pin sinks the driver current during the operational mode. The data input pin receives the incoming addressing signal during the addressing mode. The serial data output pin outputs the outgoing addressing signal during the addressing mode. The parallel data output pin outputs the readback data to a readback line. The multi-pin command interface receives the driver control signals from a control circuit via a multi-wire shared command interface. The power pin provides a supply voltage. The ground pin provides a path to ground.
In another aspect, a driver circuit for a display device includes control logic, a dual-purpose output pin, a data input pin, a parallel data output pin, a multi-pin command interface, a power pin, and a ground pin. The control logic operates in at least an addressing mode and an operational mode. In the operational mode, the control logic obtains a driver control signal and controls a driver current to an LED zone based on the driver control signal. The control logic further receives commands and outputs readback data responsive to the commands. In the addressing mode, the control logic obtains an incoming addressing signal, stores an address for the driver circuit based on the incoming addressing signal, and generates an outgoing addressing signal based on the incoming addressing signal. The dual-purpose output pin sinks the driver current during the operational mode and outputs the outgoing addressing signal during the addressing mode. The data input pin receives the incoming addressing signal during the addressing mod. The parallel data output pin outputs the readback data to a readback line. The multi-pin command interface receives the driver control signals from a control circuit via a multi-wire shared command interface. The power pin provides a supply voltage. The ground pin provides a path to ground.
The teachings of the embodiments of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings.
The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive aspect matter.
Embodiments relate to a display device that includes a control circuit, an array of light emitting diode (LED) zones, and an array of driver circuits that are distributed in the display area. The driver circuits are arranged in groups that are coupled to each other and to the control circuit in a serial communication chain via serial communication lines. The group of driver circuits are also coupled in parallel to a shared multi-wire command line that provides a high-speed interface for providing the driver control signals from the control circuit. The control circuit may issue readback commands to the driver circuits via the shared multi-wire command line or the serial communication chain. In response to the commands, the driver circuits provide readback data via a readback line through the serial communication chain or via parallel connections from the driver circuits.
Figure (
The driver circuit 120 and corresponding LED zone 130 may be embodied in an integrated package such that the LED zone 130 is stacked over the driver circuits 120 on a substrate as further described in
The display device 100 may comprise a liquid crystal display (LCD) device or an LED display device. In an LCD display device, LEDs provide white light backlighting that passes through liquid crystal color filters that control the color of individual pixels of the display. Each LED zone 130 may include LEDs corresponding to a one-dimensional or two-dimensional array of pixels. In an LED display device, LEDs are directly controlled to emit colored light corresponding to each pixel of the display device 100. Here, each LED zone 130 may comprise one or more LEDs corresponding to a single pixel or may comprise a one-dimensional array or two-dimensional array of LEDs corresponding to an array of pixels (e.g., one or more columns or rows). For example, in one embodiment, the LED zone 130 may comprise one or more groups of red, green, and blue LEDs that each correspond to a sub-pixel of a pixel. In another embodiment, the LED zone 130 may comprise one or more groups of red, green, and blue LED strings that correspond to a column or partial column of sub-pixels or a row or partial row of sub-pixels. For example, an LED zone 130 may comprise a set of red sub-pixels, a set of green sub-pixels, or a set of blue sub-pixels.
The LEDs of each LED zone 130 may be organic light emitting diodes (OLEDs), inorganic light emitting diodes (ILEDs), mini light emitting diodes (mini-LEDs) (e.g., having a size range between 100 to 300 micrometers), micro light emitting diodes (micro-LEDs) (e.g., having a size of less than 100 micrometers), white light emitting diodes (WLEDs), active-matrix OLEDs (AMOLEDs), transparent OLEDs (TOLEDs), or some other type of LEDs.
The driver circuits 120 are distributed in the display area 105 and drive corresponding LED zones 130 by controlling a drive current through the LED zones 130 based on driver control signals received from the control circuit 110. For example, the driver circuits 120 may adjust a current level and/or duty cycle of the drive current to achieve a desired brightness of the LEDs in the LED zone 130. In an embodiment, the driver circuits 120 may each control two or more color channels of an LED zone 130 (e.g., red, green, and blue color channels) via independently controllable drive currents for each channel.
In an embodiment, the driver circuits 120 may furthermore include integrated sensors. For example, the driver circuits 120 may include integrated temperature sensors, light sensors, voltage sensors, image sensors, or other sensing devices. In response to readback commands from the control circuit 110, the driver circuits 120 output requested sensor data to the control circuit 110 that may be utilized by the control circuit 110 to adjust operation of display device 100 (e.g., adjusting the driver control signals). In alternative embodiments, the display area 105 may include dedicated sensor devices (not shown) external to the driver circuits 120 that provide one or more sensing functions. The dedicated sensor device may similarly provide readback data to the control circuit 110 for adjusting operation of the display device 100.
The driver circuits 120 may be arranged in groups (e.g., rows) that share common power supply lines (including driver circuit supply lines Pwr and LED zone supply lines VLED) and control lines 115. For example, the driver circuits 120 in a group may be coupled in parallel to a shared command interface 165. Serial communication lines 155 also couple the driver circuits 120 of a group in series to each other and to the control circuit 110 to enable communications between the driver circuits 120 and the control circuit 110 via a serial communication chain. The serial communication lines 155 may be configured for unidirectional or bidirectional communication in different embodiments. In the case of unidirectional serial communication lines 155, a readback line 125 may couple the driver circuit 120 in each group to the control circuit 110. In the case of bidirectional serial communication lines 155, the readback line 125 may be optionally omitted.
The shared command interface 165 comprise a high-speed interface for communicating with the driver circuits 120. In an embodiment, the shared command interface comprises a two-wire interface including a single-ended data line providing a data signal and a single-ended clock line providing a clock signal. Data on the signal line may be synchronized with the clock signal. For example, data may be read on every rising edge, every falling edge, or both. In another embodiment, the shared command interface comprises a two-wire interface including differential data lines for transmitting a differential data signal. In this embodiment, the driver circuits 120 may include a clock recovery circuit to recover a clock providing timing of the differential data signal. In yet another embodiment, a “clockless” encoding method such as Bit Phase Mark encoding may be used to encode the differential data signal so that the data can be decoded without requiring a clock recovery circuit to recover a clock. In yet another embodiment, the shared command interface comprises a three-wire interface including differential data lines providing a differential data signal and a single-ended clock line providing a clock signal. In yet another embodiment, the shared command interface 165 may comprise a four-wire interface including differential data lines providing a differential data signal and differential clock lines providing a differential clock signal. In an embodiment, terminations are included on the shared command interface 165 at the end of each group of driver circuits 120 and compensating impedances are included along the signal path to minimize reflections. Furthermore, if the shared command interface 165 utilizes differential clock and/or data signal lines, the different lines may be flanked on both sides by an opposite polarity signal to reduce electromagnetic interference.
The driver circuits 120 include control logic that may operate in various modes including at least an addressing mode, a configuration mode, and an operational mode. During the addressing mode, the control circuit 110 initiates an addressing procedure to cause assignment of addresses to each of the driver circuits 120. During the configuration and operational modes, the control circuit 110 transmits commands and data that may be targeted to specific driver circuits 120 based on their addresses. In the configuration mode, the control circuit 110 configures driver circuits 120 with one or more operating parameters (e.g., overcurrent thresholds, overvoltage thresholds, clock division ratios, and/or slew rate control). During the operational mode, the control circuit 110 provides control data to the driver circuits 120 that causes the driver circuits to control the respective driver currents to the LED zones 130, thereby controlling brightness. The control circuit 110 may also issue commands to the driver circuits 120 during the operational mode to request readback data (e.g., sensor data), and the driver circuits 120 provide the requested readback data to the control circuit 110 in response to the commands.
The serial communication lines 155 may be utilized in the addressing mode to facilitate assignment of addresses. Here, an addressing signal is sent from the control circuit 110 via the serial communication lines 155 to the first driver circuit 120 in a group of driver circuits 120. The first driver circuit 120 stores an address based on the incoming addressing signal and generates an outgoing addressing signal for outputting to the next driver circuit 120 via the serial communication line 155. The second driver circuit 120 similarly receives the addressing signal from the first driver circuit 120, stores an address based on the incoming addressing signal, and outputs an outgoing addressing signal to the next driver circuit 120. This process continues through the chain of driver circuits 120. The last driver circuit 120 may optionally send its assigned address back to the control circuit 110 to enable the control circuit 110 to confirm that addresses have been properly assigned. The addressing process may be performed in parallel or sequentially for each group (e.g., each row) of driver circuits 120.
In an example addressing scheme, each driver circuit 120 may receive an address, store the address, increment the address by 1 or by another fixed amount, and send the incremented address as an outgoing addressing signal to the next driver circuit 120 in the group. Alternatively, each driver circuit 120 may receive the address of the prior driver circuit 120, increment the address, store the incremented address, and send the incremented address to the next driver circuit 120. In other embodiments, the driver circuit 120 may generate an address based on the incoming address signal according to a different function (e.g., decrementing).
After addressing, commands may be sent to the driver circuits 120 based on the addresses. The commands may include dimming commands to control dimming of the LED zones 130 or readback commands that request readback data from a driver circuit 120. For dimming commands, the driver circuits 120 receive the dimming data and adjust the driving currents to the corresponding LED zone 130 to achieve the desired brightness. The feedback commands may request information such as channel voltage information, temperature information, light sensing information, status information, fault information, or other data. In response to these commands, the driver circuits 120 may obtain the data from integrated sensors and send the readback data to the control circuit 110.
Commands may be sent to the driver circuits 120 via the shared command interface 165, via the serial communication lines 155 and serially connected driver circuits 120, or a combination of both. For example, in one embodiment, driver control signals for controlling dimming are sent via the shared command interface 165 while readback commands are sent via the serial communication lines 155. Alternatively, both readback commands and the driver control signals are sent via the shared command interface 165 and the serial communication lines 155 are used only for addressing and to transmit the readback data back to the control circuit 110. If commands are sent via the shared command interface 165, the targeted driver circuits 120 having the specified address processes the command while the other driver circuits 120 may ignore the command. If the commands are sent via the serial communication lines 155, the driver circuits 120 that are not targeted by the command may propagate the command to an adjacent driver circuit 120 via the serial communication lines 155 until it reaches the targeted driver circuit 120, which processes the command.
In response to a readback command, the targeted driver circuit 120 transmits the requested readback data to the control circuit 110 via the serial communication lines 155. For example, upon receiving a command, a targeted driver circuit 120 outputs the readback data to an adjacent driver circuit 120 via the serial communication lines 155. Each subsequent driver circuit 120 receives the readback data and propagates it to the next driver circuit 120 in the serial chain until it reaches the control circuit 110. Readback data can propagate through the chain in either direction. For example, the group of driver circuits 110 may propagate the readback data in a forward direction in which each driver circuit 120 outputs the readback data to an adjacent driver circuit 120 at increasing distance from the control circuit 110 until it reaches the last driver circuit 120, which then returns the readback data via the readback line 125. Alternatively, the group of driver circuits 120 may propagate the readback data in a backward direction in which each driver circuit 120 outputs the readback data to an adjacent driver circuit 120 at decreasing distance from the control circuit 110 until it reaches the control circuit 110. In an embodiment, responses to readback commands may include the address of the targeted driver circuit 120 to enable the control circuit 110 to confirm which driver circuit 120 provided the response.
In other embodiments, the control circuit 110 may issue a group command that is targeted to the group of driver circuits 120 instead of targeting an individual driver circuit 120. In this case, data may be processed by each driver circuit 120 as the command and data propagates through the chain to provide a single result to the control circuit 110. For example, in one embodiment, the control circuit 110 may issue a channel sensing command through the serial communication line 155. The first driver circuit 120 receives the channel voltage sensing command and outputs the command together with its sensed channel voltage to the next driver circuit 120. The next driver circuit 120 receives the command and the incoming channel voltage value from the previous driver circuit 120, senses its own channel voltage, and applies a function to the incoming channel voltage value and the sensed channel voltage to generate an outgoing channel voltage value that it outputs via the serial communication line 155. Here, the function may comprise a minimum function such that the driver circuit 120 compares the received channel voltage with its sensed channel voltage, and outputs via the serial communication line 155, the lower of the received channel voltage from the prior driver circuit 120 and the sensed channel voltage from the current driver circuit 120. Alternatively, the function may comprise, for example, a maximum function, an average function, or other function. This process repeats throughout the chain of driver circuits 120 so that each driver circuit 120 outputs a resulting value (e.g., a min, max, or average value) based on the sensed channel voltages detected among the current driver circuits 120 and all prior driver circuits 120. The resulting readback data received by the control circuit 110 represents a function (e.g., a min, max, or average) of each of the detected channel voltages in the group of driver circuits 120. The control circuit 110 can then set a shared supply voltage VLED for the LED zones 130 in each group or another control parameter according to the readback data. For example, by applying a minimum function to obtain the lowest channel voltage in the group, the control circuit 110 can set the supply voltage VLED for the LED zones 130 to a level sufficient to drive the LED zone 130 with the lowest sensed channel voltage to a predetermined level.
In another example, a group command may be utilized for temperature sensing. Here, the command and data are propagated through the serial communication chain in each group of driver circuit 120 as described above. At each step, a driver circuit 120 receives a temperature from an adjacent driver circuit 120, applies a function to the received temperature and its own sensed temperature to generate an outgoing temperature value, and outputs the outgoing temperature to the next driver circuit 120. Thus, the control circuit 110 can obtain a function of the sensed temperatures associated with each of the driver circuits 120 in the group. Here, the function may comprise, for example, summing or averaging, or detecting a minimum or maximum value. The control circuit 110 can then adjust the operation of the driver circuits 110 to account for temperature-dependent variations in the outputs of the LED zones 130.
In another example, a group command may be utilized for fault detection. Here, each driver circuit 120 may propagate a fault status request command through the chain and set a fault status flag if a fault is detected. The fault status flag may then be propagated to the control circuit 110 to enable the control circuit 110 to detect the faulty driver circuit 120 and adjust operation of the driver circuits 120 accordingly. In an embodiment, an address of the faulty driver circuit 120 may be sent together with the fault status flag to enable the control circuit 110 to detect the faulty driver circuit 120.
The described serial communication protocol can be utilized to calibrate a display device 100. For example, the control circuit 110 can change both the LED current and the on/off duty cycle of the driver circuits 120 in order to change the effective brightness of each LED zone 130 based on received feedback from the driver circuits 120. More specifically, the control circuit 110 may calibrate the driver circuits 120 so that LED zones 130 each output the same brightness in response to the same brightness control signal, despite process variations in the LEDs or associated circuitry that may otherwise cause variations. The calibration process may be performed by measuring light output, channel voltages, temperature, or other data that may affect performances of the LEDs using sensors in the display area 105. Alternatively, the measurements may be made by equipment outside of the display area 105, such as a separate high accuracy light meter used specifically for a calibration sequence. The calibration process may be repeated over time (e.g., as the display device 100 heats up during operation).
In other embodiments, a group of driver circuit 120 do not necessarily correspond to a row of the display area 105. In alternative embodiments, a group of serially connected driver circuit 120 coupled via serial communication lines 155 may instead correspond to a partial row of the display area 105 or a full or partial column of the display area 105. In another embodiment, a group of driver circuits 120 may correspond to a block of adjacent or non-adjacent driver circuits 120 that may span multiple rows and columns.
In different configurations, each one or more dedicated sensor circuits (not shown) may be coupled in a group of driver circuits 120. Here, the sensor circuits may have similar pin configurations and connectivity as the driver circuits 120 except they are not coupled to drive an LED zone 130. The sensor circuits may similarly facilitate addressing and readback through the serial communication chain and may similarly respond to readback commands with sensed readback data. In an example embodiment, the last element in each row may correspond to a sensor circuit. Alternatively, various sensor circuits may be interleaved with the driver circuits in a group of driver circuits 120.
The driver circuit 120 may include a power pin 124, a ground pin (Gnd) 128, one or more LED driving output pins (Out) 126, a data input pin (Di) 122, a serial data output pin 132, and a set of shared command interface pins 134.
The ground pin 128 is configured to provide a path to a ground line for the driver circuit 120, which may be common to the corresponding LED zone 130. The power pin 124 provides a connection to the driver circuit power supply line Pwr.
The data input pin 122 and the serial data output pin 132 are coupled to the serial communication lines 155 to facilitate serial communication to and from the driver circuits 120. The serial communication lines 155 may be used, for example, to assign addresses to the driver circuits 120, to send readback commands to the driver circuits 120, or to provide readback data to the control circuit 110 in response to commands as described above. As described above, in some embodiments, the data input pin 122 and serial data output pin 132 may facilitate bidirectional communication, in which case data may propagate in the reverse direction from the input pin 122 of one driver circuit 120 to a serial data output pin 132 of an adjacent driver circuit 120.
The one or more LED driving output pins 126 is coupled to the LED zone 130 to control the driver current through the LED zones 130. In an embodiment, the one or more LED driving output pins 126 may comprise a set of multiple pins to control different respective channels of the LED zone 130. For example, in an LED display device, the LED driving output 126 may include 3 pins to control red, green, and blue channels of the LED zones 130. Alternatively, in an LCD display device, the LED driving output 126 may comprise a single pin for controlling a white backlighting channel.
The set of shared command interface pins 134 facilitate communication over the shared command line interface 165. As described above, the set of shared command interface pins 134 may comprise a two-pin interface corresponding to a single-ended data line and a single-ended clock line, a two-pin interface corresponding to a pair of differential data lines, a three-pin interface corresponding to a pair of differential data lines and a single-ended clock line, or a four-pin interface corresponding to a pair of differential data lines and a pair of differential clock lines.
In another embodiment, the shared command interface 165 may comprise a bi-directional interface. In this embodiment, some or all of the readback data may be sent to the control circuit 110 via the shared command interface 165 instead of through the serial communication chain.
The display device 200 is similar to the display device 100 of
As with the embodiment of
In an embodiment, the shared command interface 265 may comprise a bi-directional interface. In this embodiment, some or all of the readback data may be sent to the control circuit 210 via the shared command interface 265 instead of through the readback line 225. In some embodiments, the readback line 225 may be omitted.
The display device 300 is similar to the display device 300 of
As with the embodiments of
In an embodiment, the shared command interface 365 may comprise a bi-directional interface. In this embodiment, some or all of the readback data may be sent to the control circuit 210 via the shared command interface 365 instead of through the readback line 325. In some embodiments, the readback line 325 may be omitted.
The integrated LED and driver circuit 405 includes a substrate 430 that is mountable on a surface of the PCB interconnect layer 420. The substrate 430 may be, e.g., a silicon (Si) substrate. In other embodiments, the substrate 430 may include various materials, such as gallium arsenide (GaAs), indium phosphide (InP), gallium nitride (GaN), AlN, sapphire, silicon carbide (SiC), or the like.
A driver circuit layer 440 may be fabricated on a surface of the substrate 430 using silicon transistor processes (e.g., BCD processing) or other transistor processes. The driver circuit layer 440 may include one or more driver circuits (e.g., a single driver circuit or a group of driver circuits arranged in an array). An interconnect layer 450 may be formed on a surface of the driver circuit layer 440. The interconnect layer 450 may include one or more metal or metal alloy materials, such as Al, Ag, Au, Pt, Ti, Cu, or any combination thereof. The interconnect layer 450 may include electrical traces to electrically connect the driver circuits in the driver circuit layer 440 to wire bonds 455, which are in turn connected to the control circuit on the PCB 410. In an embodiment, each wire bond 455 provides an electrical connection to the control circuit in accordance with the connections described in any of the preceding embodiments.
In an embodiment, the interconnect layer 450 is not necessarily distinct from the driver circuit layer 440 and these layers 440, 450 may be formed in a single process in which the interconnect layer 450 represents a top surface of the driver layer 440.
The conductive redistribution layer 460 may be formed on a surface of the interconnect layer 450. The conductive redistribution layer 460 may include a metallic grid made of a conductive material, such as Cu, Ag, Au, Al, or the like. An LED layer 470 includes LEDs that are on a surface of the conductive redistribution layer 460. The LED layer 470 may include arrays of LEDs arranged into the LED zones as described above. The conductive redistribution layer 460 provides an electrical connection between the LEDs in the LED layer 470 and the one or more driver circuits in the driver circuit layer 440 for supplying the driver current and provides a mechanical connection securing the LEDs over the substrate 430 such that the LED layer 470 and the conductive redistribution layer 460 are vertically stacked over the driver circuit layer 440.
Thus, in the illustrated circuit 400, the one or more driver circuits and the LED zones including the LEDs are integrated in a single package including a substrate 430 with the LEDs in an LED layer 470 stacked over the driver circuits in the driver circuit layer 440. By stacking the LED layer 470 over the driver circuit layer 440 in this manner, the driver circuits can be distributed in the display area of a display device.
In alternative embodiments, the integrated driver and LED circuits 405, 485, 495 may be mounted to a different base such as a glass base instead of the PCB 410.
The PCB 410 includes a connection to a power source supplying power (e.g., VLED) to the LEDs, a control circuit for generating a control signal, generic I/O connections, and a ground (GND) connection. The driver circuit layer 440 includes a plurality of driver circuits (e.g., DC1, DC2, . . . DCn) and a demultiplexer DeMux. The conductive redistribution layer 460 provides electrical connections between the driver circuits and the demultiplexer DeMux in the driver circuit layer 440 to the plurality of LEDs in the LED layer 470. The LED layer 470 includes a plurality of LEDs arranged in rows and columns. In this example implementation, each column of LEDs is electrically connected via the conductive redistribution layer 460 to one driver circuit in the driver circuit layer 440. The electrical connection established between each driver circuit and its respective column of LEDs controls the supply of driver current from the driver circuit to the column. In this embodiment each diode shown in the LED layer corresponds to an LED zone. Each row of LEDs is electrically connected via the conductive redistribution layer 460 to one output (e.g., VLED_1, VLED_2, . . . VLED_M) of the demultiplexer DeMux in the driver circuit layer 440. The demultiplexer DeMux in the driver circuit layer 440 is connected to a power supply (VLED) and a control signal from the PCB 410. The control signal instructs the demultiplexer DeMux which row or rows of LEDs are to be enabled and supplied with power using the VLED lines. Thus, a particular LED in the LED layer 470 is activated when power (VLED) is supplied on its associated row and the driver current is supplied to its associated column.
Upon reading this disclosure, those of skill in the art will appreciate still additional alternative embodiments through the disclosed principles herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those skilled in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the scope described herein.
This application is a continuation of U.S. application Ser. No. 17/026,136, filed Sep. 18, 2020, now U.S. Pat. No. 10,909,911, which is incorporated by reference in its entirety.
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