Display device with feedback via serial connections between distributed driver circuits

Embodiments relate to a display device that includes a control circuit, an array of light emitting diode (LED) zones, and an array of zone integrated circuits that are distributed in the display area. The zone integrated circuits may comprise integrated LED and driver circuits and may include sensor circuits. The zone integrated 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 control circuit provides control signals that control the driver circuits to drive the LED zones and may provide commands to request readback data from the zone integrated circuits. Responsive to the commands, the zone integrated circuits output readback data to the control circuit via the serial communication chain.

BACKGROUND

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.

SUMMARY

In a first aspect, a display device comprises an array of light emitting diode zones, a group of driver circuits distributed in the display area, a control circuit, and a set of serial communication lines coupled between adjacent driver circuits in the group and to the control circuit in a serial communication chain. 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 light emitting diode zones each comprise one or more light emitting diodes that generate light in response to respective driver currents. Furthermore, responsive to a target driver circuit in the group of driver circuits receiving a command signal from the control circuit, the target driver circuit outputs a readback signal and the group of driver circuits propagates the readback signal from the target driver circuit through the serial communication chain to the control circuit.

In a second aspect, a driver circuit comprises control logic, and a set of external pins including at least an LED driving output pin, a data input pin, a data output 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. 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 controls the driver current during the operational mode. The data input pin receives the incoming addressing signal during the addressing mode and receives commands or data from a previous driver circuit in a serial communication chain during the operational mode. The data output pin outputs the outgoing addressing signal during the addressing mode and outputs the commands or data to a next driver circuit in the serial communication chain during the operational mode. The ground pin provides a path to ground.

In a third aspect, a zone integrated circuit for a display device comprises one or more LEDs of an LED zone and a driver circuit stacked under the one or more LEDs on a substrate in an integrated package. The driver circuit may comprise the features described above.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments relate to a display device that includes a control circuit, an array of light emitting diode (LED) zones, and an array of zone integrated circuits that are distributed in the display area. The zone integrated circuits may comprise integrated LED and driver circuits and may include sensor circuits. The zone integrated 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 control circuit provides control signals that control the driver circuits to drive the LED zones and may provide commands to request readback data from the zone integrated circuits. Responsive to the commands, the zone integrated circuits output readback data to the control circuit via the serial communication chain.

Figure (FIG. 1is a circuit diagram of an electronic device100. In one example embodiment, the electronic device100can be a display device for displaying images or video. In various embodiments, the electronic device100may be implemented in any suitable form-factor, including a display screen for a computer display panel, a television, a mobile device, a billboard, etc. The electronic device100may 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. In an LED display device, LEDs are directly controlled to emit colored light corresponding to each pixel of the display. In other embodiments, the electronic device100may comprise an array of sensors (e.g., temperature sensors, light sensors, voltage sensors) that may be utilized in conjunction with a display device or other device.

The electronic device100may include a device array105and a control circuit110. The device array105comprises an array of zone integrated circuits (ICs)150(e.g., a two-dimensional array comprising rows and columns). In a display device, at least some of the zone ICs150may each include an LED zone130comprising one or more LEDs and an associated driver circuit120that drives the LED zone130. The driver circuit120and corresponding LED zone130may be embodied in an integrated package such that the LED zone130is stacked over the driver circuits120on a substrate as further described inFIGS. 10-12. Alternatively, a zone IC150may comprise a driver circuit120coupled to an external LED zone that is not necessarily integrated with the driver circuit120.

In an LCD display, an LED zone130can includes one or more LEDs that provides backlighting for a backlighting zone, which may include a one-dimensional or two-dimensional array of pixels. In an LED display, the LED zone130may 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 zone130may 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 zone130may 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 zone130may 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 zone130may 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 zone ICs150may furthermore include integrated sensors. For example, the driver circuit120may include one or more integrated sensors such as integrated temperature sensors, light sensors, voltage sensors, image sensors, or other sensing devices. In other instances, a zone IC150may comprise a dedicated sensor device that does not drive an LED zone130and instead performs one or more sensing functions.

The zone ICs150may be arranged in groups (e.g., rows) that share common power supply lines (including driver circuit supply lines and LED zone supply lines) and/or communication lines. For example, the zone ICs150in a group may be coupled in parallel to a shared command line165. In an embodiment, the shared command line165may comprise a power communication line that supplies both power and data to the zone IC150as a supply voltage modulated with digital data. Alternatively, the shared command line165may comprise a dedicated signal line and power may be supplied to the zone ICs150via a separate dedicated supply line (not shown).

Serial communication lines155also couple the zone ICs150of a group in series to each other and to the control circuit110to enable communications between the zone ICs150and the control circuit110via a serial chain. The serial communication lines155may be configured for unidirectional or bidirectional communication in different embodiments. In the case of unidirectional serial communication lines155, a readback line125may couple the last zone IC150-N in each group to the control circuit110. In the case of bidirectional serial communication lines155, the readback line125may be optionally omitted.

The zone ICs150may operate in various modes including at least an addressing mode, a configuration mode, and an operational mode. During the addressing mode, the control circuit110initiates an addressing procedure to cause assignment of addresses to each of the zone ICs150. During the configuration and operational modes, the control circuit110transmits commands and data that may be targeted to specific zone ICs150based on their addresses. In the configuration mode, the control circuit110configures driver circuits120with 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 circuit110provides control data to the driver circuits120that causes the driver circuits to control the respective driver currents to the LED zones130, thereby controlling brightness. The control circuit110may also issue commands to the zone ICs150during the operational mode to request readback data (e.g., sensor data), and the zone ICs150provide the requested readback data to the control circuit110in response to the commands.

The serial communication lines155may be utilized in the addressing mode to facilitate assignment of addresses. Here, an addressing signal is sent from the control circuit110via the serial communication lines155to the first zone IC150-1in a group of zone ICs150. The first zone IC150-1stores an address based on the incoming addressing signal and generates an outgoing addressing signal for outputting to the next zone IC150-2via the serial communication line155. The second zone IC150-2similarly receives the addressing signal from the first zone IC150-1, stores an address based on the incoming addressing signal, and outputs an outgoing addressing signal to the next zone IC150-3. This process continues through the chain of zone ICs150. The last zone IC150-N may optionally send its assigned address back to the control circuit110to enable the control circuit110to confirm that addresses have been properly assigned. The addressing process may be performed in parallel or sequentially for each group of zone ICs150.

In an example addressing scheme, each zone IC150may 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 zone IC150in the group. Alternatively, each zone IC150may receive the address of the prior zone IC150, increment the address, store the incremented address, and send the incremented address to the next zone IC150. In other embodiments, the zone IC150may 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 zone ICs150based on the addresses. The commands may include dimming commands to control dimming of the LED zones130or readback commands that request readback data from a zone IC150. For dimming commands, the driver circuits120receive the dimming data and adjust the driving currents to the corresponding LED zone130to 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 zone ICs150may obtain the data from integrated sensors and send the readback data to the control circuit110.

Commands may be sent to the zone ICs150via the shared command line165or via the serial communication lines155and serially connected zone ICs150. If commands are sent via the shared command line165, the targeted zone IC150having the specified address processes the command while the other zone ICs150may ignore the command. If the commands are sent via the serial communication lines155, the zone ICs150that are not targeted by the command may propagate the command to an adjacent zone IC150via the serial communication lines155until it reaches the targeted zone IC150, which processes the command.

In response to a readback command, the targeted zone IC150transmit the requested readback data to the control circuit150via the serial communication lines155. For example, upon receiving a command, a targeted zone IC150outputs the readback data to an adjacent zone IC150via the serial communication lines155. Each subsequent zone IC150receives the readback data and propagates it to the next zone IC150in the serial chain until it reaches the control circuit110. Readback data can propagate through the chain in either direction. For example, the group of driver circuits110may propagate the readback data in a forward direction in which each zone IC150outputs the readback data to an adjacent zone IC150at increasing distance from the control circuit110until it reaches the last zone IC150, which then returns the readback data via the readback line125. Alternatively, the group of driver circuits110may propagate the readback data in a backward direction in which each zone IC150outputs the readback data to an adjacent zone IC150at decreasing distance from the control circuit110until it reaches the control circuit110. In an embodiment, responses to readback commands may include the address of the targeted zone IC150to enable the control circuit110to confirm which zone IC150provided the response.

In other embodiments, the control circuit110may issue a group command that is targeted to the group of zone ICs150instead of targeting an individual zone IC150. In this case, data may be combined by each zone IC150as the command and data propagates through the chain to provide a single result to the control circuit110. For example, in one embodiment, the control circuit110may issue a channel sensing command through the serial communication line155. The first zone IC150-1receives the channel voltage sensing command and outputs the command together with its sensed channel voltage to the next zone IC150-2. The next zone IC150-2receives the command and the incoming channel voltage value from the previous zone IC150-2, 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 line155. Here, the function may comprise a minimum function such that the zone IC150-2compares the received channel voltage with its sensed channel voltage, and outputs via the serial communication line155, the lower of the received channel voltage from the prior zone IC150-2and the sensed channel voltage from the current driver circuit220. Alternatively, the function may comprise, for example, a max function, an average function, or other function. This process repeats throughout the chain of zone ICs150so that each zone IC150outputs a resulting value (e.g., a min, max, or average value) based on the sensed channel voltages detected among the current zone ICs150and all prior zone ICs150. The resulting readback data received by the control circuit110represents a function (e.g., a min, max, or average) of each of the detected channel voltages in the group of zone ICs150. The control circuit110can then set a shared supply voltage for the LED zones130in 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 circuit110can set the supply voltage for the LED zones130to a minimum level sufficient to drive the LED zone230with the lowest sensed channel voltage.

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 zone ICs150as described above. At each step, a zone IC150receives a temperature from an adjacent zone IC150, 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 zone IC150. Thus, the control circuit110can obtain a function of the sensed temperatures associated with each of the zone ICs150in the group. Here, the function may comprise, for example, summing or averaging, or detecting a minimum or maximum value. The control circuit110can then adjust the operation of the driver circuits110to account for temperature-dependent variations in the outputs of the LED zones130.

In another example, a group command may be utilized for fault detection. Here, each zone IC150may 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 circuit110to enable the control circuit110to detect the faulty zone IC150and adjust operation of the driver circuits110accordingly. In an embodiment, an address of the faulty zone IC150may be sent together with the fault status flag to enable the control circuit120to detect the faulty zone IC150.

The described serial communication protocol can be utilized to calibrate a display device100. For example, the control circuit110can change both the LED current and the on/off duty cycle of the driver circuits120in order to change the effective brightness of each LED zone130based on received feedback from the zone ICs150. More specifically, the control circuit110may calibrate the driver circuits120so that LED zones130each 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 device array105. The calibration process may be repeated over time (e.g., as the electronic device100heats up during operation).

In other embodiments, a group of zone ICs150do not necessarily correspond to a row of the device array105. In alternative embodiments, a group of serially connected zone ICs150coupled via serial communication lines155may instead correspond to a partial row of the device array105or a full or partial column of the device array105. In another embodiment, a group of zone ICs150may correspond to a block of adjacent or non-adjacent zone ICs150that may span multiple rows and columns.

In different configurations, each group of zone ICs150may include some number of circuits with an integrated driver circuit120and LED zone130and some number of sensing circuits. For example, the last zone IC150-N in each row may correspond to a sensing circuit, or various sensor circuits may be interleaved with driver and LED circuits in each group of zone ICs150.

FIG. 2is a circuit diagram of a display device200for displaying images or video utilizing the communication protocol described above. A display area205comprises an array of pixels for displaying images based on data received from the control circuit210. In various embodiments, the display area205may include LED zones230, a set of distributed driver circuits220, power supply lines including VLED lines (e.g., VLED_1, . . . VLED_M) and ground (GND) lines, and various signaling lines including serial communication lines255that serially couple the driver circuits220to each other and to the control circuit210, power communication lines265, and an optional readback line225. The VLED lines provide power to the LED zones230(e.g., by supplying power to the anode of the LEDs in the LED zones230). The GND lines provide a path to ground for the LED zones230and the driver circuits220. The driver circuits220may include one or more integrated sensors. Furthermore, the display device200may optionally include one or more dedicated sensor circuits in a serial chain with the driver circuits220and that shares the same power communication lines265and ground lines225of the driver circuits220.

The driver circuit220may include a four-pin configuration. In the four-pin configuration, the driver circuit220may include a data input pin (Di)222, a power line communication input pin (PLCi)224, one or more output pins (Out)226, and a ground pin (Gnd)228. In an embodiment, the output226may comprise a set of multiple pins to control multiple channels of the LED zone230. For example, the output226may include 3 pins to control red, green, and blue channels of the LED zones230.

The ground pin228is configured to provide a path to a ground line for the driver circuit220, which may be common to the corresponding LED zone230.

The power line communication input pin224is configured to receive a power line communication signal from the control circuit210via the common power communication lines265(e.g., Pwr1, Pwr2, . . . PwrM) for each group. The power line communication signal includes a supply voltage that may be modulated to encode the driver control signal or other control information as digital data. For example, the power line communication signal may encode operating parameter information or control data information for operating the driver circuit220and controlling brightness of the LED zones230. The power communication line265may also be utilized to send commands to the driver circuits220during the operational mode to request status information such as channel voltage information, temperature information, fault information, or other data. In some embodiments, the power line communication signal supplies a direct current voltage between 3 and 12 volts for the supply voltage. In one embodiment, the power line communication signal may provide a power supply voltage of more than 4.5 volts with a digital data signal having a maximum data rate of up to 2 megahertz (MHz) with a 0.5 peak-to-peak voltage signal.

The data input pin222and the output pin226are coupled to the serial communication lines255to facilitate serial communication to and from the driver circuits220. The serial communication lines255may be used, for example, to assign addresses to the driver circuits220or provide readback data to the control circuit210in response to commands as described above. As described above, in some embodiments, the data input pin222and output pin226may facilitate bidirectional communication, in which case data may propagate in the reverse direction from the input pin222of one driver circuit220to an output pin226of an adjacent driver circuit220. If bidirectional communication is used, the readback line225may be optionally omitted. Optionally, the serial communication lines255can furthermore be used to provide commands to the driver circuits220during the operational mode, instead of or in addition to utilizing the power communication lines265for this purpose.

The output pin226serves a dual-purpose dependent on the mode of operation. In the addressing mode and during readback operations, the output pin226facilitates communications on the serial communication lines255as described above. In the operational mode of the display device200, the output pin226is coupled to sink current from a corresponding LED zone230to control supply of the driver current235.

Because the 4-pin driver circuits220ofFIG. 2utilize a shared output pin226that is used for both serial communication and for driving the LED zones230, the driver circuits220time the serial communications to occur when the LED zones230are not actively being driven to avoid interference with the operation of the LED zones230. Thus, in one embodiment, serial communication is performed only during times when the duty cycles of the driver circuits220are not driving the LED zones230.

In an embodiment, since each of the driver circuits220in a group are coupled to the same power communication line265providing the brightness control signals, each driver circuit220can detect and process the brightness control signals associated with adjacent driver circuits220to determine their drive timing. This allows a particular driver circuit220, k, to determine if the adjacent driver circuit220(e.g., k−1 or k+1) is driving its LED zone230and the end time of the duty cycle. This enables the driver circuit220kto provide data on the serial communication lines255during its own off times and the off time of the adjacent driver circuit220to which it is communicating.

For example, a data transfer operation is initiated for a driver circuit220kvia a PLC command on the PLC input pin224, via a command from the data input pin222, or via logic internal to the driver circuit220(e.g., in response to a detected fault condition or a periodic condition). The data transfer operation may be utilized to read data from the driver circuit220kin response to a command, or to enable the driver circuit220kto pass a command or data to an adjacent driver circuit (e.g., driver circuit k−1 or k+1). The driver circuit220kdetects when an adjacent serial communication line225is available. For example, if transmitting in the forward direction, the driver circuit220kdetects when the serial communication line255to the driver circuit220k+1 is available. In this case, the serial communication line255is generally available when the driver circuit220kis not driving its corresponding LED zone230via its output pin226. If transmitting in the reverse direction, the driver circuit220kdetects when the serial communication line255to the driver circuit220k−1 is available. In this case, the serial communication line255to the driver circuit220k−1 is available when the driver circuit220k−1 is not driving its corresponding LED zone230via the output pin226of the driver circuit220k−1. The driver circuit220kmay determine the timing of when the output pin226of the driver circuit220k−1 is available based on the brightness data for the driver circuit220k−1 sent via a shared line accessible to the driver circuit220k(e.g., via the PLC line265). The driver circuit220kthen performs the transfer operation during these detected off times. In an embodiment, the driver circuit220kmay perform a data transfer over multiple cycles (e.g., multiple periods when the serial communication line is available255in between driving the LED zone230) if there is insufficient time to perform the entire transfer during one cycle. A similar process may be performed by each driver circuit220in a chain to serially transfer data to or from the control circuit210.

In alternative architectures, one or more of the sensor circuits (not shown) may be coupled in series in between adjacent driver circuits220. The sensing circuits may include similar pin configurations and external connections as the driver circuits220except that the output pins226of sensor circuits are not coupled to drive an LED zone230. The sensor circuits may furthermore provide similar capabilities for facilitating serial communications within the group. In a specific example, the last element in each row may comprise a sensor circuit. In some embodiments where the readback line225is omitted, the last element in each row may comprise a 3-pin sensor device instead of a 4-pin device because separate input and output pins are not needed.

FIG. 3is an example circuit diagram of the driver circuit220, according to one embodiment. The driver circuit220may include a voltage pre-regulation circuit310, an Rx_PHY320, a low-dropout regulator LDO_D330, an oscillator OSC340, control logic350, an output driver360, a pulse width modulation (PWM) dimming circuit370, a transistor375, and a brightness control circuit380. In various embodiments, the driver circuit220may include additional, fewer, or different components.

The Rx_PHY320is a physical layer that demodulates the PLC data from the PLC signal and provides the corresponding digital data to the control logic350. In an example embodiment, the Rx_PHY320provides a connection with a maximum bandwidth of 2 MHz with a cascade of 36 stages.

The voltage pre-regulation circuit310performs pre-regulation of the power line communication signal. In one embodiment, the voltage pre-regulation circuit310comprises a first order RC filter followed by a source follower. The voltage pre-regulator310may optionally be omitted and the PLC signal may instead pass directly to the LDO-D330. The power line communication signal is also provided to the Rx_PHY320. The pre-regulated supply voltage is provided to the LDO_D330. The LDO_D330converts the pre-regulated supply voltage into a steady direct current voltage (which may be lower than the pre-regulated supply voltage) used to power the oscillator OSC340and control logic350. In an example embodiment, the steady direct current voltage may be 1.8 volts. The oscillator OSC340provides a clock signal to the control logic350.

The control logic350receives the driver control signal from the Rx_PHY320, the direct current voltage from the LDO_D330, and the clock signal from the oscillator OSC340. The control logic350may also receive digital data from the data input pin222and output an enable signal352, a data output signal354, a PWM clock selection signal PWMCLK_sel356, and a maximum current signal Max. Current358. During the addressing mode or when the driver circuit220outputs or receives command or data signals during the operational mode, the control logic350activates the enable signal352to enable the output driver360. The output driver360buffers the output signal354to the output pin226when the enable signal352is activated. When the output driver360is active, the control logic350may control the PWM dimming circuit370to turn off the transistor375to effectively block the current path from the LEDs.

When driving the LED zones230, the control logic deactivates the enable signal352and the driver360is tri-stated to effectively decouple it from the output pin226. The PWM clock selection signal PWMCLK_sel356specifies a duty cycle for controlling PWM dimming by the PWM dimming circuit370. Based on the selected duty cycle, the PWM dimming circuit370controls timing of an on-state and an off-state of the transistor375. During the on-state of the transistor375, a current path is established from the output pin226(coupled to the LED zones230) to the ground pin228through the transistor375and the brightness control circuit380to sink the driver current through the LEDs of the LEDs zones230. During an off-state of the transistor375, the current path is interrupted to block current from flowing through the LED zones230. The brightness control circuit380receives the maximum current signal Max. Current358from the control logic350and controls the current level that flows through the LEDs (from the output pin226to the ground pin228) when the transistor375is in the on-state. During the operational mode, the control logic350controls the duty cycle of the PWM dimming circuit370and the maximum current Max. Current358of the brightness control circuit380to set the LED zones230to the desired brightness.

As described above, the data input pin222and the output pin226may optionally be bidirectional. In this case, the output driver360may be a bidirectional driver that can also receive data or commands from the output pin226when the driver is not driving the LED zone230and the control logic350may output data or commands to the data input pin222.

As described above, alternative embodiments may include multiple output pins226for driving multiple channels of the LED zones230(e.g.,3output pins226to drive three channels of LEDs). In this case, the driver circuit220may include parallel transistors375and associated control lines for driving each channel.

FIG. 4illustrates an alternative embodiment of a display device400including a control circuit410, a set of control lines415, and a display area405. The display area405includes an array of driver circuits420for driving respective LED zones430via a driver current435. The driver circuits420each include a PLC pin424, a data input pin422, an LED driving output pin426, a data output pin432, and a ground pin428. Serial communication lines455couple the control circuit410to a data input pin422of the first driver circuit420in a group of driver circuits420and couple serially between the data output pin432and the data input pin432of adjacent driver circuits420. A readback line425optionally couples the data output pin432of the last driver circuit420in the group to the control circuit410. A power communication line465couples to a power communication pin424of each driver circuit420in a group. Furthermore, a ground line couples to ground pins428of each driver circuit420in the group.

The display device400is similar to the display device200ofFIG. 2, but the driver circuits420include separate LED driving output pins426and data output pins (Do)432instead of a shared output pin226. This embodiment enables the Di/Do pins422/432to be used as dedicated data transfer pins and enable a driver circuit420to perform data transfers concurrently with the driver circuit420actively driving an LED zone430. Thus, the driver circuits420ofFIG. 4can continuously transfer data using the serial chain independently of the LED dimming cycles. Furthermore, the serial communication lines455can be used to send commands from the control circuit410(instead of relying on the power communication line465). For example, in one communication scheme, the power communication line465is used to send brightness data to the driver circuits420for driving the LED zones430while other commands for obtaining various readback data (e.g., sensor data) is sent via the serial communication lines455.

In this implementation, the control circuit410can send various commands to the driver circuits420via a serial communication line455coupled to the data input (Di) pin of the first driver circuit420in the chain. If the command is a targeted command, the first driver circuit420in the chain determines if the target address matches its address. If it does not match, the driver circuit420passes the command to the next driver circuit via the serial communication lines455. Otherwise, the driver circuit420sends the readback data via the serial communication lines455. The command and/or feedback data may then similarly propagate through the chain of driver circuits420, with the final driver circuit420in the chain providing feedback data back to the control circuit410via the readback line425. Alternatively, data may be propagated backwards through the chain (from the Di pin422of one driver circuit420to the Do pin432of the previous driver circuit420). In this case, the display device400does not necessarily include the readback line425. Commands requesting group data (e.g., the lowest channel voltage in the group or combined temperature in the group) may similarly be processed through the serial communication chain in the same manner described above. For example, each driver circuit420may combine a received temperature with its own sensed temperature and a combined temperature value as described above. Or each driver circuit420may compare a received channel voltage with its own sensed channel voltage and send the lower channel voltage through the serial chain as described above.

As described above with respect toFIG. 2, one or more sensor circuits (not shown) may be coupled in series in between adjacent driver circuits420. The sensor circuits may include similar pin configurations and external connections as the driver circuits420except that they do not drive LED zones230and the LED driving output pins426may be omitted in the sensor circuits. The sensor circuits may provide similar capabilities for facilitating serial communications within the group as described above.

FIG. 5illustrates an example embodiment of a driver circuit420that includes a dedicated data output pin432and LED driving output pin426in the 5-pin configuration described above. The driver circuit420includes a voltage pre-regulation circuit510, an Rx_Phy520, a low dropout regulator530, an oscillator540control logic550, a PWM dimming controller570, a PWM transistor575, and a brightness control circuit580. These components operate similarly to the analogous components in the driver circuit220ofFIG. 3, except the output driver360and corresponding enable logic may be omitted and the control logic550may instead output directly to the data output pin432. Based on this architecture, the control logic550can communicate via the data output pin432while the driver circuit420concurrently sinks current via the LED driving output pin426to drive the LED zones430. Like the driver circuit220ofFIG. 2, the driver circuit420may optionally provide bidirectional communication between the data input pin422and the data output pin432.

FIG. 6illustrates another embodiment of a display device600including a control circuit610, a set of control lines615, and a display area605. The display area605includes an array of driver circuits620for driving respective LED zones630via a driver current635. The driver circuits620each include a power pin624, a data input pin622, an LED driving output pin626, a data output pin632, and a ground pin628. Serial communication lines655couple the control circuit610to a data input pin622of the first driver circuit620in a group of driver circuits620and couple serially between the data output pin632and the data input pin622of adjacent driver circuits620. A readback line625optionally couples the data output pin632of the last driver circuit620in the group to the control circuit610. A power line665couples to a power pin624of each driver circuit620in a group. Furthermore, a ground line couples to ground pins628of each driver circuit620in the group.

The display device600ofFIG. 6is similar to the display device400ofFIG. 4except that it does not use power line communication and instead includes a dedicated power line665that provides power to both the driver circuits620and the LED zones630within a group, but does not provide modulated data. Thus, in this embodiment, all commands (including brightness data for driving the LED zones630and readback commands) are sent through the serial communication lines655and the serially connected driver circuits620. The driver circuits620may optionally obtain addresses during the addressing mode as described above via the serial communication lines655. In other embodiments, the driver circuits620in this embodiment are not necessarily individually addressable. In this case, the driver circuits620operate as clock-less shift registers to serially shift data through the chain of driver circuits620. In one embodiment, Bit-Phase Mark encoding is used to extract a clock and shift data into the driver circuits620. The data may also be shifted all the way through each of the driver circuits620in the serial chain and then shifted out again (e.g., in the reverse direction or in the forward direction using the readback line625) to be used for error detection. In this embodiment, data is written to all the driver circuits620each time the brightness control signal changes.

In an embodiment, each driver circuit620includes a register that holds information transferred to it from the previous driver circuit620in the chain. At the input pin622, a Bit-Phase-Mark to Binary converter converts the input signal from a Bit-Phase-Mark encoding to a binary encoding. At the data output pin632of each driver circuit620, a Binary to Bit-Phase-Mark converter converts the data back to a Bit-Phase-Mark encoding for transmission via the serial communication lines655. In other embodiments, different encodings may be used.

If addresses are individually assigned, each driver circuit620examines packets that arrive via the serial communication lines655to determine if the address matches its stored address. If the addresses match, then the driver circuit620executes the command coupled with that address. For example, if the command is a brightness setting then the driver circuit620adjusts the LED brightness. If the command is a temperature request, then the driver circuit outputs its temperature (and its corresponding address) with the proper command to indicate that the data should be passed through the remaining driver circuits620back to the control circuit610. If the incoming address does not match the address of the driver circuit620, then the command coupled with its intended address is passed onto the next driver circuit620via the serial communication lines655.

FIG. 7illustrates another alternative embodiment of a display device700including a control circuit710, a set of control lines715, and a display area705. The display area705includes an array of driver circuits720for driving respective LED zones730via a driver current735. The driver circuits720each include a power pin724, a data input pin722, an LED driving output pin726, a data output pin732, a dimming input pin734, and a ground pin728. Serial communication lines755couple the control circuit710to a data input pin722of the first driver circuit720in a group of driver circuits720and couple serially between the data output pin732and the data input pin722of adjacent driver circuits720. A readback line725optionally couples the data output pin732of the last driver circuit720in the group to the control circuit710. Each driver circuit720in a group is furthermore coupled in parallel to a shared power line765(coupled to respective power pins724of each driver circuit720), ground lines Gnd (coupled to respective ground pins728), and dimming control line775(coupled to respective dimming input pins734).

The display device700is similar to the display device400ofFIG. 4except that instead of using power line communication, a dedicated dimming control line775provides commands or data to the driver circuit720(e.g., LED driving data such as brightness information or readback commands) via respective dimming input pins734and a separate power line provides power via respective power input pins724(without modulated data). Here, the serial communication lines755may be used during the addressing phase as described above. Furthermore, the serial communication lines755may be utilized to provide readback data in response to commands received via the dimming input pins734. As described above, the serial communication lines755may be unidirectional (with data returning to the control circuit710via a readback line725) or bidirectional (with readback data returning to the control circuit710via the serial communication lines755in the reverse direction). In some embodiments, commands or data may instead be sent to the driver circuits720via the serial communication lines755instead of or in addition to the dimming control line775.

As described for previous embodiments, one or more sensor circuits (not shown) may be coupled in series in between adjacent driver circuits720. The sensor circuits may include similar pin configurations and external connections as the driver circuits720except that the sensor circuits do not drive LED zones730and the LED driving output pins426may be omitted in the sensor circuits. In other embodiments, if readback commands are sent through the serial communication lines755, the dimming input pin734may also be omitted in the sensing circuits. The sensing circuits may provide similar capabilities for facilitating serial communications within the group as described above.

FIG. 8illustrates an example embodiment of a driver circuit720. The driver circuit720includes a voltage pre-regulation circuit810, an Rx_Phy820, a low dropout regulator830, an oscillator840control logic850, a PWM dimming controller870, a PWM transistor875, and a brightness control circuit880. These components operate similarly to the analogous components in the driver circuit420ofFIG. 5except the Rx_Phy820is coupled to receive commands via the dimming input pin734instead of via power line communication. The power pin724supplies power without modulated data.

FIG. 9is an example circuit diagram of a control circuit910that may correspond to the control circuits110,210,410,610, or710of any of the preceding embodiments. The control circuit910controls operation of the display device based on signals communicated on control lines915as described above. The control circuit910may include a timing controller930and a bridge920. The control circuit910may control the display device using either active matrix (AM) or passive matrix (PM) driving methods.

The timing controller930generates an image control signal915indicating values for driving pixels of the display device and timing for driving the pixels. For example, the timing controller930controls timing of image or video frames and controls timing of driving each of the LED zones within an image or video frame. Furthermore, the timing controller930controls the brightness for driving each of the LED zones during a given image or video frame. The image control signal915is provided by the timing controller930to the bridge920.

The bridge920translates the image control signal915to generate the various signals to the device array including, for example, power communication signals, dimming signals, command signals, or other signals described in any of the preceding embodiments. Furthermore, the bridge920may receive feedback signals from the device array via the control lines915and adjust operation accordingly as described in any of the preceding embodiments.

FIG. 10Ais a cross sectional view of a first embodiment of a zone IC1000that includes an integrated LED and driver circuit1005in a single package. In the example shown inFIG. 10A, the circuit1000includes a printed circuit board (PCB)1010, a PCB interconnect layer1020, and the integrated LED and driver circuit1005which comprises a substrate1030, a driver circuit layer1040, an interconnect layer1050, a conductive redistribution layer1060, and an LED layer1070. Bonded wires1055may be included for connections between the PCB interconnect layer1020and the integrated LED and driver circuit1005. The PCB1010comprises a support board for mounting the integrated LED and driver circuit1005, the control circuit and various other supporting electronics. The PCB1010may include internal electrical traces and/or vias that provide electrical connections between the electronics. A PCB interconnect layer1020may be formed on a surface of the PCB1010. The PCB interconnect layer1020includes pads for mounting the various electronics and traces for connecting between them.

The integrated LED and driver circuit1005includes a substrate1030that is mountable on a surface of the PCB interconnect layer1020. The substrate1030may be, e.g., a silicon (Si) substrate. In other embodiments, the substrate1030may 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 layer1040may be fabricated on a surface of the substrate1030using silicon transistor processes (e.g., BCD processing) or other transistor processes. The driver circuit layer1040may include one or more driver circuits (e.g., a single driver circuit or a group of driver circuits arranged in an array). An interconnect layer1050may be formed on a surface of the driver circuit layer1040. The interconnect layer1050may include one or more metal or metal alloy materials, such as Al, Ag, Au, Pt, Ti, Cu, or any combination thereof. The interconnect layer1050may include electrical traces to electrically connect the driver circuits in the driver circuit layer1040to wire bonds1055, which are in turn connected to the control circuit on the PCB1010. In an embodiment, each wire bond1055provides an electrical connection to the control circuit in accordance with the connections described in any of the preceding embodiments.

In an embodiment, the interconnect layer1050is not necessarily distinct from the driver circuit layer1040and these layers1040,1050may be formed in a single process in which the interconnect layer1050represents a top surface of the driver layer1040.

The conductive redistribution layer1060may be formed on a surface of the interconnect layer1050. The conductive redistribution layer1060may include a metallic grid made of a conductive material, such as Cu, Ag, Au, Al, or the like. An LED layer1070includes LEDs that are on a surface of the conductive redistribution layer1060. The LED layer1070may include arrays of LEDs arranged into the LED zones as described above. The conductive redistribution layer1060provides an electrical connection between the LEDs in the LED layer1070and the one or more driver circuits in the driver circuit layer1040for supplying the driver current and provides a mechanical connection securing the LEDs over the substrate1030such that the LED layer1070and the conductive redistribution layer1060are vertically stacked over the driver circuit layer1040.

Thus, in the illustrated circuit1000, the one or more driver circuits and the LED zones including the LEDs are integrated in a single package including a substrate1030with the LEDs in an LED layer1070stacked over the driver circuits in the driver circuit layer1040. By stacking the LED layer1070over the driver circuit layer1040in this manner, the driver circuits can be distributed in the display area of a display device.

FIG. 10Bis a cross sectional view of a second embodiment of a display device1080including an integrated LED and driver circuit1085, according to one embodiment. The device1080is substantially similar to the device1000described inFIG. 10Abut utilizes vias1032and corresponding connected solder balls1034to make electrical connections between the driver circuit layer1040and the PCB1010instead of the wires1055. Here, the vias1032are plated vertical electrical connections that pass completely through the substrate layer1030. In one embodiment, the substrate layer1030is a Si substrate and the through-chip vias1032are Through Silicon Vias (TSVs). The through-chip vias1032are etched into and through the substrate layer1030during fabrication and may be filled with a metal, such as tungsten (W), copper (C), or other conductive material. The solder balls1034comprise a conductive material that provide an electrical and mechanical connection to the plating of the vias1032and electrical traces on the PCB interconnect layer1020. In one embodiment, each via1032provides an electrical connection for providing signals such as the driver control signal from the control circuit on the PCB1010to a group of driver circuits on the driver circuit layer1040. The vias1032may also provide connections for the incoming and outgoing addressing signals, the supply voltage (e.g., VLED) to the LEDs in a LED zone on the LED layer1070, and a path to a circuit ground (GND).

FIG. 10Cis a cross sectional view of a third embodiment of a display device1090including an integrated LED and driver circuit1095. The device1090is substantially similar to the device1080described inFIG. 10Bbut includes the driver circuit layer1040and interconnect layer1050on the opposite side of the substrate1030from the conductive redistribution layer1060and the LED layer1070. In this embodiment, the interconnect layer1050and the driver circuit layer1040are electrically connected to the PCB1010via a lower conductive redistribution layer1065and solder balls1034. The lower conductive redistribution layer1065and solder balls1034provide mechanical and electrical connections (e.g., for the driver control signals) between the driver circuit layer1040and the PCB interconnect layer1020. The driver circuit layer1040and interconnect layer1050are electrically connected to the conductive redistribution layer1060and the LEDs of the LED layer1070via one or more plated vias1032through the substrate1030. The one or more vias1032seen inFIG. 10Cmay be utilized to provide the driver currents from the driver circuits in the driver circuit layer1040to the LEDs in the LED layer1070and other signals as described above

In alternative embodiments, the integrated driver and LED circuits1005,1085,1095may be mounted to a different base such as a glass base instead of the PCB1010.

FIG. 11is a top down view of a display device using an integrated LED and driver circuit2300, according to one embodiment. The circuit1100can correspond to a top view of any of the integrated LED and driver circuits1005,1085,1095depicted inFIGS. 10A-10C. A plurality of LEDs of an LED lay1070is arranged in rows and columns (e.g., C1, C2, C3, . . . Cn−1, Cn). For passive matrix architectures, each row of LEDs of the LED layer1070is connected by a conductive redistribution layer1060to a demultiplexer which outputs a plurality of VLED signals (i.e., VLED_1 . . . VLED_M). The VLED signals provide power (i.e., a supply voltage) to a corresponding row of LEDs of the LED layer1070via the conductive redistribution layer1060.

FIG. 12illustrates a schematic view1200of several layers of a display device with an integrated LED and driver circuit, according to one embodiment. The schematic view includes the PCB1010, the driver circuit layer1040, the conductive redistribution layer1060, and the LED layer1070as described inFIGS. 10A-10C. The schematic ofFIG. 12shows circuit connections for the circuits1005,1085,1095ofFIGS. 10A-10Cbut does not reflect the physical layout. As described above, in the physical layout, the LED layer1070is positioned on top of (i.e., vertically stacked over) the conductive redistribution layer1060. The conductive redistribution layer1060is positioned on top of the driver circuit layer1040and the driver circuit layer1040is positioned on top of the PCB1010.

The PCB1010includes 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 layer1040includes a plurality of driver circuits (e.g., DC1, DC2, . . . DCn) and a demultiplexer DeMux. The conductive redistribution layer1060provides electrical connections between the driver circuits and the demultiplexer DeMux in the driver circuit layer1040to the plurality of LEDs in the LED layer1070. The LED layer1070includes a plurality of LEDs arranged in rows and columns. In this example implementation, each column of LEDs is electrically connected via the conductive redistribution layer1060to one driver circuit in the driver circuit layer1040. 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 layer1060to one output (e.g., VLED_1, VLED_2, . . . VLED_M) of the demultiplexer DeMux in the driver circuit layer1040. The demultiplexer DeMux in the driver circuit layer1040is connected to a power supply (VLED) and a control signal from the PCB1010. 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 layer1070is activated when power (VLED) is supplied on its associated row and the driver current is supplied to its associated column.