U.S. patent application number 17/498672 was filed with the patent office on 2022-01-27 for display device with feedback via serial connections between distributed driver circuits.
The applicant listed for this patent is Huayuan Semiconductor (Shenzhen) Limited Company. Invention is credited to Yung-Ting Chen, Lilun Chi, Richard Landry Gray, Chih-Chang Wei, Junjie Zheng.
Application Number | 20220028337 17/498672 |
Document ID | / |
Family ID | 1000005897986 |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220028337 |
Kind Code |
A1 |
Wei; Chih-Chang ; et
al. |
January 27, 2022 |
DISPLAY DEVICE WITH FEEDBACK VIA SERIAL CONNECTIONS BETWEEN
DISTRIBUTED DRIVER CIRCUITS
Abstract
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.
Inventors: |
Wei; Chih-Chang; (Taoyuan
City, TW) ; Zheng; Junjie; (Cupertino, CA) ;
Gray; Richard Landry; (Taipei City, TW) ; Chen;
Yung-Ting; (Changhua County, TW) ; Chi; Lilun;
(Taipei City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huayuan Semiconductor (Shenzhen) Limited Company |
Shenzhen |
|
CN |
|
|
Family ID: |
1000005897986 |
Appl. No.: |
17/498672 |
Filed: |
October 11, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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17067427 |
Oct 9, 2020 |
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17498672 |
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63029389 |
May 22, 2020 |
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63042548 |
Jun 22, 2020 |
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63059737 |
Jul 31, 2020 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G 2320/0693 20130101;
G09G 2310/0243 20130101; G09G 2320/041 20130101; G09G 2310/0286
20130101; G09G 2320/0626 20130101; G09G 2300/0804 20130101; G09G
3/3233 20130101; G09G 2330/12 20130101; G09G 2330/02 20130101; G09G
2370/00 20130101; G09G 2330/08 20130101; G09G 3/3426 20130101 |
International
Class: |
G09G 3/3233 20160101
G09G003/3233; G09G 3/34 20060101 G09G003/34 |
Claims
1. A driver circuit for a display device comprising: control logic
to operate in an operational mode during which the control logic
obtains a driver control signal and controls a driver current to an
LED zone based on the driver control signal; an LED driving output
pin to drive the driver current during the operational mode; and a
data input pin to receive commands or data from a previous driver
circuit in a serial communication chain during the operational
mode; a data output pin to output readback data to a next driver
circuit in the serial communication chain during the operational
mode responsive to the commands including a readback command for
the driver circuit, the readback data propagated through the serial
communication chain back to a control circuit; and a ground pin to
provide a path to ground.
2. The driver circuit of claim 1, wherein the control logic is
further configured to operate in at least an addressing mode during
which 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 for
another driver circuit based on the incoming addressing signal.
3. The driver circuit of claim 2, wherein the data input pin is
further configured to receive the incoming addressing signal from
the previous driver circuit in the serial communication chain
during the addressing mode.
4. The driver circuit of claim 1, further comprising: a power line
communication pin coupled to a power communication line, the power
line communication pin configured to provide a supply voltage to
the driver circuit and the driver control signal, wherein the
driver control signal is digital data modulated on the supply
voltage.
5. The driver circuit of claim 1, further comprising: a shared
command line input pin to receive the driver control signals; and a
power pin to receive a supply voltage.
6. The driver circuit of claim 1, wherein the control logic is
configured to operate as a serial shift register to obtain an
incoming driver control signal via the data input pin and to output
an outgoing driver control signal via the data output pin.
7. The driver circuit of claim 6, wherein the outgoing driver
control signal outputted via the data output pin is for another
driver circuit connected to the driver circuit via the serial
communication chain.
8. The driver circuit of claim 1, wherein the LED driving output
pin is configured to drive the driver current by sinking the driver
current during the operational mode.
9. The driver circuit of claim 1, wherein the data input pin is
further configured to propagate the readback signal in a forward
direction to the previous driver circuit in the serial
communication chain.
10. The driver circuit of claim 2, wherein the LED driving output
pin and the data output pin are configured as a single pin
configured to drive the driver current during the operational mode
and output the outgoing addressing signal during the addressing
mode.
11. A zone integrated circuit for a display device comprising: one
or more LEDs of an LED zone; a driver circuit stacked under the one
or more LEDs on a substrate in an integrated package, the driver
circuit comprising: control logic to operate in an operational mode
during which the control logic obtains a driver control signal and
controls a driver current to an LED zone based on the driver
control signal; an LED driving output pin to drive the driver
current during the operational mode; a data input pin to receive
commands or data from a previous driver circuit in a serial
communication chain during the operational mode; a data output pin
to output readback data to a next driver circuit in the serial
communication chain during the operational mode responsive to the
commands including a readback command for the driver circuit, the
readback data propagated through the serial communication chain
back to a control circuit; and a ground pin to provide a path to
ground.
12. The zone integrated circuit of claim 11, wherein the control
logic is further configured to operate in at least an addressing
mode during which 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 for another driver circuit based on the incoming addressing
signal.
13. The zone integrated circuit of claim 12, wherein the data input
pin is further configured to receive the incoming addressing signal
during the addressing mode from the previous driver circuit in the
serial communication chain during the addressing mode.
14. The zone integrated circuit of claim 11, further comprising: a
power line communication pin coupled to a power communication line,
the power line communication pin configured to provide a supply
voltage to the driver circuit and the driver control signal,
wherein the driver control signal is digital data modulated on the
supply voltage.
15. The zone integrated circuit of claim 11, further comprising: a
shared command line input pin to receive the driver control
signals; and a power pin to receive a supply voltage.
16. The zone integrated circuit of claim 11, wherein the control
logic is configured to operate as a serial shift register to obtain
an incoming driver control signal via the data input pin and to
output an outgoing driver control signal via the data output
pin.
17. The zone integrated circuit of claim 16, wherein the outgoing
driver control signal outputted via the data output pin is for
another driver circuit connected to the driver circuit via the
serial communication chain.
18. The zone integrated circuit of claim 11, wherein the LED
driving output pin is configured to drive the driver current by
sinking the driver current during the operational mode.
19. The zone integrated circuit of claim 11, wherein the data input
pin is further configured to propagate the readback signal in a
forward direction to the previous driver circuit in the serial
communication chain.
20. The zone integrated circuit of claim 12, wherein the LED
driving output pin and the data output pin are configured as a
single pin to drive the driver current during the operational mode
and output the outgoing addressing signal during the addressing
mode.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 17/067,427 filed on Oct. 9, 2020, which claims
the benefit of U.S. Provisional Application No. 63/029,389 filed on
May 22, 2020, U.S. Provisional Application No. 63/042,548 filed on
Jun. 22, 2020, and U.S. Provisional Application No. 63/059,737
filed on Jul. 31, 2020, each of which are hereby incorporated by
reference in its entirety.
BACKGROUND
[0002] 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.
[0003] 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
[0004] 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.
[0005] 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.
[0006] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] 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.
[0008] Figure (FIG. 1 is a circuit diagram of a display device
including distributed driver circuits that provide feedback via a
serial communication chain, according to one embodiment.
[0009] FIG. 2 is a circuit diagram of a display device including a
4-pin architecture for groups of distributed driver circuits that
provide feedback via a serial communication chain, according to one
embodiment.
[0010] FIG. 3 is a circuit diagram of a 4-pin architecture of a
driver circuit for a display device, according to one
embodiment.
[0011] FIG. 4 is a circuit diagram of a display device including a
first embodiment of a 5-pin architecture for groups of distributed
driver circuits that provide feedback via a serial communication
chain, according to one embodiment.
[0012] FIG. 5 is a circuit diagram of the first embodiment of the
5-pin architecture of a driver circuit for a display device,
according to one embodiment.
[0013] FIG. 6 is a circuit diagram of a display device including a
second embodiment of a 5-pin architecture for groups of distributed
driver circuits that provide feedback via a serial communication
chain, according to one embodiment.
[0014] FIG. 7 is a circuit diagram of a display device including a
6-pin architecture for distributed driver circuits that provide
feedback via a serial communication chain, according to one
embodiment.
[0015] FIG. 8 is a circuit diagram of a 6-pin architecture of a
driver circuit for a display device, according to one
embodiment.
[0016] FIG. 9 is a block diagram of a control circuit for a display
device, according to one embodiment.
[0017] FIG. 10A is a cross sectional view of a first embodiment of
an LED and driver circuit that may be utilized in a display
device.
[0018] FIG. 10B is a cross sectional view of a second embodiment of
an LED and driver circuit that may be utilized in a display
device.
[0019] FIG. 10C is a cross sectional view of a third embodiment of
an LED and driver circuit that may be utilized in a display
device.
[0020] FIG. 11 is a top down view of a display device using an LED
and driver circuit, according to one embodiment.
[0021] FIG. 12 illustrates a schematic view of several layers of an
LED and driver circuit for a display device, according to one
embodiment.
[0022] 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 or 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.
DETAILED DESCRIPTION OF EMBODIMENTS
[0023] 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.
[0024] Figure (FIG. 1 is a circuit diagram of an electronic device
100. In one example embodiment, the electronic device 100 can be a
display device for displaying images or video. In various
embodiments, the electronic device 100 may 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 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. 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 device 100 may 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.
[0025] The electronic device 100 may include a device array 105 and
a control circuit 110. The device array 105 comprises 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 ICs 150 may each include an LED zone 130 comprising one or
more LEDs and an associated driver circuit 120 that drives the LED
zone 130. 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 FIGS. 10-12. Alternatively, a zone IC 150 may comprise
a driver circuit 120 coupled to an external LED zone that is not
necessarily integrated with the driver circuit 120.
[0026] In an LCD display, an LED zone 130 can 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 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.
[0027] 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.
[0028] The zone ICs 150 may furthermore include integrated sensors.
For example, the driver circuit 120 may 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 IC 150 may comprise a dedicated sensor
device that does not drive an LED zone 130 and instead performs one
or more sensing functions.
[0029] The zone ICs 150 may 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 ICs 150 in a group may be coupled in parallel to
a shared command line 165. In an embodiment, the shared command
line 165 may comprise a power communication line that supplies both
power and data to the zone IC 150 as a supply voltage modulated
with digital data. Alternatively, the shared command line 165 may
comprise a dedicated signal line and power may be supplied to the
zone ICs 150 via a separate dedicated supply line (not shown).
[0030] Serial communication lines 155 also couple the zone ICs 150
of a group in series to each other and to the control circuit 110
to enable communications between the zone ICs 150 and the control
circuit 110 via a serial 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 last
zone IC 150-N 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.
[0031] The zone ICs 150 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 zone ICs 150. During the configuration and operational modes,
the control circuit 110 transmits commands and data that may be
targeted to specific zone ICs 150 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
zone ICs 150 during the operational mode to request readback data
(e.g., sensor data), and the zone ICs 150 provide the requested
readback data to the control circuit 110 in response to the
commands.
[0032] 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 zone IC 150-1 in a
group of zone ICs 150. The first zone IC 150-1 stores an address
based on the incoming addressing signal and generates an outgoing
addressing signal for outputting to the next zone IC 150-2 via the
serial communication line 155. The second zone IC 150-2 similarly
receives the addressing signal from the first zone IC 150-1, stores
an address based on the incoming addressing signal, and outputs an
outgoing addressing signal to the next zone IC 150-3. This process
continues through the chain of zone ICs 150. The last zone IC 150-N
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 of zone ICs
150.
[0033] In an example addressing scheme, each zone IC 150 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 zone IC 150 in the group.
Alternatively, each zone IC 150 may receive the address of the
prior zone IC 150, increment the address, store the incremented
address, and send the incremented address to the next zone IC 150.
In other embodiments, the zone IC 150 may generate an address based
on the incoming address signal according to a different function
(e.g., decrementing).
[0034] After addressing, commands may be sent to the zone ICs 150
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 zone IC 150. 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 zone ICs 150 may obtain the data
from integrated sensors and send the readback data to the control
circuit 110.
[0035] Commands may be sent to the zone ICs 150 via the shared
command line 165 or via the serial communication lines 155 and
serially connected zone ICs 150. If commands are sent via the
shared command line 165, the targeted zone IC 150 having the
specified address processes the command while the other zone ICs
150 may ignore the command. If the commands are sent via the serial
communication lines 155, the zone ICs 150 that are not targeted by
the command may propagate the command to an adjacent zone IC 150
via the serial communication lines 155 until it reaches the
targeted zone IC 150, which processes the command.
[0036] In response to a readback command, the targeted zone IC 150
transmit the requested readback data to the control circuit 150 via
the serial communication lines 155. For example, upon receiving a
command, a targeted zone IC 150 outputs the readback data to an
adjacent zone IC 150 via the serial communication lines 155. Each
subsequent zone IC 150 receives the readback data and propagates it
to the next zone IC 150 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 zone IC 150 outputs the readback data to an adjacent zone IC
150 at increasing distance from the control circuit 110 until it
reaches the last zone IC 150, which then returns the readback data
via the readback line 125. Alternatively, the group of driver
circuits 110 may propagate the readback data in a backward
direction in which each zone IC 150 outputs the readback data to an
adjacent zone IC 150 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 zone IC 150 to enable the control circuit 110 to
confirm which zone IC 150 provided the response.
[0037] In other embodiments, the control circuit 110 may issue a
group command that is targeted to the group of zone ICs 150 instead
of targeting an individual zone IC 150. In this case, data may be
combined by each zone IC 150 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 zone IC 150-1 receives the channel voltage
sensing command and outputs the command together with its sensed
channel voltage to the next zone IC 150-2. The next zone IC 150-2
receives the command and the incoming channel voltage value from
the previous zone IC 150-2, 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 line 155. Here,
the function may comprise a minimum function such that the zone IC
150-2 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 zone IC 150-2
and the sensed channel voltage from the current driver circuit 220.
Alternatively, the function may comprise, for example, a max
function, an average function, or other function. This process
repeats throughout the chain of zone ICs 150 so that each zone IC
150 outputs a resulting value (e.g., a min, max, or average value)
based on the sensed channel voltages detected among the current
zone ICs 150 and all prior zone ICs 150. 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 zone ICs 150. The control circuit 110 can
then set a shared supply voltage 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 for the LED zones 130 to a minimum level sufficient
to drive the LED zone 230 with the lowest sensed channel
voltage.
[0038] 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 ICs
150 as described above. At each step, a zone IC 150 receives a
temperature from an adjacent zone IC 150, 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 IC 150. Thus, the control circuit 110 can obtain a
function of the sensed temperatures associated with each of the
zone ICs 150 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.
[0039] In another example, a group command may be utilized for
fault detection. Here, each zone IC 150 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 zone IC 150 and adjust operation of the
driver circuits 110 accordingly. In an embodiment, an address of
the faulty zone IC 150 may be sent together with the fault status
flag to enable the control circuit 120 to detect the faulty zone IC
150.
[0040] 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 zone ICs
150. 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 device array 105. The calibration process may be
repeated over time (e.g., as the electronic device 100 heats up
during operation).
[0041] In other embodiments, a group of zone ICs 150 do not
necessarily correspond to a row of the device array 105. In
alternative embodiments, a group of serially connected zone ICs 150
coupled via serial communication lines 155 may instead correspond
to a partial row of the device array 105 or a full or partial
column of the device array 105. In another embodiment, a group of
zone ICs 150 may correspond to a block of adjacent or non-adjacent
zone ICs 150 that may span multiple rows and columns.
[0042] In different configurations, each group of zone ICs 150 may
include some number of circuits with an integrated driver circuit
120 and LED zone 130 and some number of sensing circuits. For
example, the last zone IC 150-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 ICs 150.
[0043] FIG. 2 is a circuit diagram of a display device 200 for
displaying images or video utilizing the communication protocol
described above. A display area 205 comprises an array of pixels
for displaying images based on data received from the control
circuit 210. In various embodiments, the display area 205 may
include LED zones 230, a set of distributed driver circuits 220,
power supply lines including VLED lines (e.g., VLED_1, . . .
VLED_M) and ground (GND) lines, and various signaling lines
including serial communication lines 255 that serially couple the
driver circuits 220 to each other and to the control circuit 210,
power communication lines 265, and an optional readback line 225.
The VLED lines provide power to the LED zones 230 (e.g., by
supplying power to the anode of the LEDs in the LED zones 230). The
GND lines provide a path to ground for the LED zones 230 and the
driver circuits 220. The driver circuits 220 may include one or
more integrated sensors. Furthermore, the display device 200 may
optionally include one or more dedicated sensor circuits in a
serial chain with the driver circuits 220 and that shares the same
power communication lines 265 and ground lines 225 of the driver
circuits 220.
[0044] The driver circuit 220 may include a four-pin configuration.
In the four-pin configuration, the driver circuit 220 may 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 output 226 may comprise a set of
multiple pins to control multiple channels of the LED zone 230. For
example, the output 226 may include 3 pins to control red, green,
and blue channels of the LED zones 230.
[0045] The ground pin 228 is configured to provide a path to a
ground line for the driver circuit 220, which may be common to the
corresponding LED zone 230.
[0046] The power line communication input pin 224 is configured to
receive a power line communication signal from the control circuit
210 via the common power communication lines 265 (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 circuit 220 and controlling brightness of the
LED zones 230. The power communication line 265 may also be
utilized to send commands to the driver circuits 220 during 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.
[0047] The data input pin 222 and the output pin 226 are coupled to
the serial communication lines 255 to facilitate serial
communication to and from the driver circuits 220. The serial
communication lines 255 may be used, for example, to assign
addresses to the driver circuits 220 or provide readback data to
the control circuit 210 in response to commands as described above.
As described above, in some embodiments, the data input pin 222 and
output pin 226 may facilitate bidirectional communication, in which
case data may propagate in the reverse direction from the input pin
222 of one driver circuit 220 to an output pin 226 of an adjacent
driver circuit 220. If bidirectional communication is used, the
readback line 225 may be optionally omitted. Optionally, the serial
communication lines 255 can furthermore be used to provide commands
to the driver circuits 220 during the operational mode, instead of
or in addition to utilizing the power communication lines 265 for
this purpose.
[0048] The output pin 226 serves a dual-purpose dependent on the
mode of operation. In the addressing mode and during readback
operations, the output pin 226 facilitates communications on the
serial communication lines 255 as described above. In the
operational mode of the display device 200, the output pin 226 is
coupled to sink current from a corresponding LED zone 230 to
control supply of the driver current 235.
[0049] Because the 4-pin driver circuits 220 of FIG. 2 utilize a
shared output pin 226 that is used for both serial communication
and for driving the LED zones 230, the driver circuits 220 time the
serial communications to occur when the LED zones 230 are not
actively being driven to avoid interference with the operation of
the LED zones 230. Thus, in one embodiment, serial communication is
performed only during times when the duty cycles of the driver
circuits 220 are not driving the LED zones 230.
[0050] In an embodiment, since each of the driver circuits 220 in a
group are coupled to the same power communication line 265
providing the brightness control signals, each driver circuit 220
can detect and process the brightness control signals associated
with adjacent driver circuits 220 to determine their drive timing.
This allows a particular driver circuit 220, k, to determine if the
adjacent driver circuit 220 (e.g., k-1 or k+1) is driving its LED
zone 230 and the end time of the duty cycle. This enables the
driver circuit 220 k to provide data on the serial communication
lines 255 during its own off times and the off time of the adjacent
driver circuit 220 to which it is communicating.
[0051] For example, a data transfer operation is initiated for a
driver circuit 220 k via a PLC command on the PLC input pin 224,
via a command from the data input pin 222, or via logic internal to
the driver circuit 220 (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 circuit 220 k in response
to a command, or to enable the driver circuit 220 k to pass a
command or data to an adjacent driver circuit (e.g., driver circuit
k-1 or k+1). The driver circuit 220 k detects when an adjacent
serial communication line 225 is available. For example, if
transmitting in the forward direction, the driver circuit 220 k
detects when the serial communication line 255 to the driver
circuit 220 k+1 is available. In this case, the serial
communication line 255 is generally available when the driver
circuit 220 k is not driving its corresponding LED zone 230 via its
output pin 226. If transmitting in the reverse direction, the
driver circuit 220 k detects when the serial communication line 255
to the driver circuit 220 k-1 is available. In this case, the
serial communication line 255 to the driver circuit 220 k-1 is
available when the driver circuit 220 k-1 is not driving its
corresponding LED zone 230 via the output pin 226 of the driver
circuit 220 k-1. The driver circuit 220 k may determine the timing
of when the output pin 226 of the driver circuit 220 k-1 is
available based on the brightness data for the driver circuit 220
k-1 sent via a shared line accessible to the driver circuit 220 k
(e.g., via the PLC line 265). The driver circuit 220 k then
performs the transfer operation during these detected off times. In
an embodiment, the driver circuit 220 k may perform a data transfer
over multiple cycles (e.g., multiple periods when the serial
communication line is available 255 in between driving the LED zone
230) if there is insufficient time to perform the entire transfer
during one cycle. A similar process may be performed by each driver
circuit 220 in a chain to serially transfer data to or from the
control circuit 210.
[0052] In alternative architectures, one or more of the sensor
circuits (not shown) may be coupled in series in between adjacent
driver circuits 220. The sensing circuits may include similar pin
configurations and external connections as the driver circuits 220
except that the output pins 226 of sensor circuits are not coupled
to drive an LED zone 230. 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 line 225 is 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.
[0053] FIG. 3 is an example circuit diagram of the driver circuit
220, according to one embodiment. The driver circuit 220 may
include a voltage pre-regulation circuit 310, an Rx_PHY 320, a
low-dropout regulator LDO_D 330, an oscillator OSC 340, control
logic 350, an output driver 360, a pulse width modulation (PWM)
dimming circuit 370, a transistor 375, and a brightness control
circuit 380. In various embodiments, the driver circuit 220 may
include additional, fewer, or different components.
[0054] The Rx_PHY 320 is a physical layer that demodulates the PLC
data from the PLC signal and provides the corresponding digital
data to the control logic 350. In an example embodiment, the Rx_PHY
320 provides a connection with a maximum bandwidth of 2 MHz with a
cascade of 36 stages.
[0055] The voltage pre-regulation circuit 310 performs
pre-regulation of the power line communication signal. In one
embodiment, the voltage pre-regulation circuit 310 comprises a
first order RC filter followed by a source follower. The voltage
pre-regulator 310 may optionally be omitted and the PLC signal may
instead pass directly to the LDO-D 330. The power line
communication signal is also provided to the Rx_PHY 320. The
pre-regulated supply voltage is provided to the LDO_D 330. The
LDO_D 330 converts 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 OSC 340 and control
logic 350. In an example embodiment, the steady direct current
voltage may be 1.8 volts. The oscillator OSC 340 provides a clock
signal to the control logic 350.
[0056] The control logic 350 receives the driver control signal
from the Rx_PHY 320, the direct current voltage from the LDO_D 330,
and the clock signal from the oscillator OSC 340. The control logic
350 may also receive digital data from the data input pin 222 and
output an enable signal 352, a data output signal 354, a PWM clock
selection signal PWMCLK_sel 356, and a maximum current signal Max.
Current 358. During the addressing mode or when the driver circuit
220 outputs or receives command or data signals during the
operational mode, the control logic 350 activates the enable signal
352 to enable the output driver 360. The output driver 360 buffers
the output signal 354 to the output pin 226 when the enable signal
352 is activated. When the output driver 360 is active, the control
logic 350 may control the PWM dimming circuit 370 to turn off the
transistor 375 to effectively block the current path from the
LEDs.
[0057] When driving the LED zones 230, the control logic
deactivates the enable signal 352 and the driver 360 is tri-stated
to effectively decouple it from the output pin 226. The PWM clock
selection signal PWMCLK_sel 356 specifies a duty cycle for
controlling PWM dimming by the PWM dimming circuit 370. Based on
the selected duty cycle, the PWM dimming circuit 370 controls
timing of an on-state and an off-state of the transistor 375.
During the on-state of the transistor 375, a current path is
established from the output pin 226 (coupled to the LED zones 230)
to the ground pin 228 through the transistor 375 and the brightness
control circuit 380 to sink the driver current through the LEDs of
the LEDs zones 230. During an off-state of the transistor 375, the
current path is interrupted to block current from flowing through
the LED zones 230. The brightness control circuit 380 receives the
maximum current signal Max. Current 358 from the control logic 350
and controls the current level that flows through the LEDs (from
the output pin 226 to the ground pin 228) when the transistor 375
is in the on-state. During the operational mode, the control logic
350 controls the duty cycle of the PWM dimming circuit 370 and the
maximum current Max. Current 358 of the brightness control circuit
380 to set the LED zones 230 to the desired brightness.
[0058] As described above, the data input pin 222 and the output
pin 226 may optionally be bidirectional. In this case, the output
driver 360 may be a bidirectional driver that can also receive data
or commands from the output pin 226 when the driver is not driving
the LED zone 230 and the control logic 350 may output data or
commands to the data input pin 222.
[0059] As described above, alternative embodiments may include
multiple output pins 226 for driving multiple channels of the LED
zones 230 (e.g., 3 output pins 226 to drive three channels of
LEDs). In this case, the driver circuit 220 may include parallel
transistors 375 and associated control lines for driving each
channel.
[0060] FIG. 4 illustrates an alternative embodiment of a display
device 400 including a control circuit 410, a set of control lines
415, and a display area 405. The display area 405 includes an array
of driver circuits 420 for driving respective LED zones 430 via a
driver current 435. The driver circuits 420 each include a PLC pin
424, a data input pin 422, an LED driving output pin 426, a data
output pin 432, and a ground pin 428. Serial communication lines
455 couple the control circuit 410 to a data input pin 422 of the
first driver circuit 420 in a group of driver circuits 420 and
couple serially between the data output pin 432 and the data input
pin 432 of adjacent driver circuits 420. A readback line 425
optionally couples the data output pin 432 of the last driver
circuit 420 in the group to the control circuit 410. A power
communication line 465 couples to a power communication pin 424 of
each driver circuit 420 in a group. Furthermore, a ground line
couples to ground pins 428 of each driver circuit 420 in the
group.
[0061] The display device 400 is similar to the display device 200
of FIG. 2, but the driver circuits 420 include separate LED driving
output pins 426 and data output pins (Do) 432 instead of a shared
output pin 226. This embodiment enables the Di/Do pins 422/432 to
be used as dedicated data transfer pins and enable a driver circuit
420 to perform data transfers concurrently with the driver circuit
420 actively driving an LED zone 430. Thus, the driver circuits 420
of FIG. 4 can continuously transfer data using the serial chain
independently of the LED dimming cycles. Furthermore, the serial
communication lines 455 can be used to send commands from the
control circuit 410 (instead of relying on the power communication
line 465). For example, in one communication scheme, the power
communication line 465 is used to send brightness data to the
driver circuits 420 for driving the LED zones 430 while other
commands for obtaining various readback data (e.g., sensor data) is
sent via the serial communication lines 455.
[0062] In this implementation, the control circuit 410 can send
various commands to the driver circuits 420 via a serial
communication line 455 coupled to the data input (Di) pin of the
first driver circuit 420 in the chain. If the command is a targeted
command, the first driver circuit 420 in the chain determines if
the target address matches its address. If it does not match, the
driver circuit 420 passes the command to the next driver circuit
via the serial communication lines 455. Otherwise, the driver
circuit 420 sends the readback data via the serial communication
lines 455. The command and/or feedback data may then similarly
propagate through the chain of driver circuits 420, with the final
driver circuit 420 in the chain providing feedback data back to the
control circuit 410 via the readback line 425. Alternatively, data
may be propagated backwards through the chain (from the Di pin 422
of one driver circuit 420 to the Do pin 432 of the previous driver
circuit 420). In this case, the display device 400 does not
necessarily include the readback line 425. 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 circuit 420 may combine a received
temperature with its own sensed temperature and a combined
temperature value as described above. Or each driver circuit 420
may compare a received channel voltage with its own sensed channel
voltage and send the lower channel voltage through the serial chain
as described above.
[0063] As described above with respect to FIG. 2, one or more
sensor circuits (not shown) may be coupled in series in between
adjacent driver circuits 420. The sensor circuits may include
similar pin configurations and external connections as the driver
circuits 420 except that they do not drive LED zones 230 and the
LED driving output pins 426 may be omitted in the sensor circuits.
The sensor circuits may provide similar capabilities for
facilitating serial communications within the group as described
above.
[0064] FIG. 5 illustrates an example embodiment of a driver circuit
420 that includes a dedicated data output pin 432 and LED driving
output pin 426 in the 5-pin configuration described above. The
driver circuit 420 includes a voltage pre-regulation circuit 510,
an Rx_Phy 520, a low dropout regulator 530, an oscillator 540
control logic 550, a PWM dimming controller 570, a PWM transistor
575, and a brightness control circuit 580. These components operate
similarly to the analogous components in the driver circuit 220 of
FIG. 3, except the output driver 360 and corresponding enable logic
may be omitted and the control logic 550 may instead output
directly to the data output pin 432. Based on this architecture,
the control logic 550 can communicate via the data output pin 432
while the driver circuit 420 concurrently sinks current via the LED
driving output pin 426 to drive the LED zones 430. Like the driver
circuit 220 of FIG. 2, the driver circuit 420 may optionally
provide bidirectional communication between the data input pin 422
and the data output pin 432.
[0065] FIG. 6 illustrates another embodiment of a display device
600 including a control circuit 610, a set of control lines 615,
and a display area 605. The display area 605 includes an array of
driver circuits 620 for driving respective LED zones 630 via a
driver current 635. The driver circuits 620 each include a power
pin 624, a data input pin 622, an LED driving output pin 626, a
data output pin 632, and a ground pin 628. Serial communication
lines 655 couple the control circuit 610 to a data input pin 622 of
the first driver circuit 620 in a group of driver circuits 620 and
couple serially between the data output pin 632 and the data input
pin 622 of adjacent driver circuits 620. A readback line 625
optionally couples the data output pin 632 of the last driver
circuit 620 in the group to the control circuit 610. A power line
665 couples to a power pin 624 of each driver circuit 620 in a
group. Furthermore, a ground line couples to ground pins 628 of
each driver circuit 620 in the group.
[0066] The display device 600 of FIG. 6 is similar to the display
device 400 of FIG. 4 except that it does not use power line
communication and instead includes a dedicated power line 665 that
provides power to both the driver circuits 620 and the LED zones
630 within a group, but does not provide modulated data. Thus, in
this embodiment, all commands (including brightness data for
driving the LED zones 630 and readback commands) are sent through
the serial communication lines 655 and the serially connected
driver circuits 620. The driver circuits 620 may optionally obtain
addresses during the addressing mode as described above via the
serial communication lines 655. In other embodiments, the driver
circuits 620 in this embodiment are not necessarily individually
addressable. In this case, the driver circuits 620 operate as
clock-less shift registers to serially shift data through the chain
of driver circuits 620. In one embodiment, Bit-Phase Mark encoding
is used to extract a clock and shift data into the driver circuits
620. The data may also be shifted all the way through each of the
driver circuits 620 in the serial chain and then shifted out again
(e.g., in the reverse direction or in the forward direction using
the readback line 625) to be used for error detection. In this
embodiment, data is written to all the driver circuits 620 each
time the brightness control signal changes.
[0067] In an embodiment, each driver circuit 620 includes a
register that holds information transferred to it from the previous
driver circuit 620 in the chain. At the input pin 622, 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
pin 632 of each driver circuit 620, a Binary to Bit-Phase-Mark
converter converts the data back to a Bit-Phase-Mark encoding for
transmission via the serial communication lines 655. In other
embodiments, different encodings may be used.
[0068] If addresses are individually assigned, each driver circuit
620 examines packets that arrive via the serial communication lines
655 to determine if the address matches its stored address. If the
addresses match, then the driver circuit 620 executes the command
coupled with that address. For example, if the command is a
brightness setting then the driver circuit 620 adjusts 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 circuits 620 back to the
control circuit 610. If the incoming address does not match the
address of the driver circuit 620, then the command coupled with
its intended address is passed onto the next driver circuit 620 via
the serial communication lines 655.
[0069] FIG. 7 illustrates another alternative embodiment of a
display device 700 including a control circuit 710, a set of
control lines 715, and a display area 705. The display area 705
includes an array of driver circuits 720 for driving respective LED
zones 730 via a driver current 735. The driver circuits 720 each
include a power pin 724, a data input pin 722, an LED driving
output pin 726, a data output pin 732, a dimming input pin 734, and
a ground pin 728. Serial communication lines 755 couple the control
circuit 710 to a data input pin 722 of the first driver circuit 720
in a group of driver circuits 720 and couple serially between the
data output pin 732 and the data input pin 722 of adjacent driver
circuits 720. A readback line 725 optionally couples the data
output pin 732 of the last driver circuit 720 in the group to the
control circuit 710. Each driver circuit 720 in a group is
furthermore coupled in parallel to a shared power line 765 (coupled
to respective power pins 724 of each driver circuit 720), ground
lines Gnd (coupled to respective ground pins 728), and dimming
control line 775 (coupled to respective dimming input pins
734).
[0070] The display device 700 is similar to the display device 400
of FIG. 4 except that instead of using power line communication, a
dedicated dimming control line 775 provides commands or data to the
driver circuit 720 (e.g., LED driving data such as brightness
information or readback commands) via respective dimming input pins
734 and a separate power line provides power via respective power
input pins 724 (without modulated data). Here, the serial
communication lines 755 may be used during the addressing phase as
described above. Furthermore, the serial communication lines 755
may be utilized to provide readback data in response to commands
received via the dimming input pins 734. As described above, the
serial communication lines 755 may be unidirectional (with data
returning to the control circuit 710 via a readback line 725) or
bidirectional (with readback data returning to the control circuit
710 via the serial communication lines 755 in the reverse
direction). In some embodiments, commands or data may instead be
sent to the driver circuits 720 via the serial communication lines
755 instead of or in addition to the dimming control line 775.
[0071] As described for previous embodiments, one or more sensor
circuits (not shown) may be coupled in series in between adjacent
driver circuits 720. The sensor circuits may include similar pin
configurations and external connections as the driver circuits 720
except that the sensor circuits do not drive LED zones 730 and the
LED driving output pins 426 may be omitted in the sensor circuits.
In other embodiments, if readback commands are sent through the
serial communication lines 755, the dimming input pin 734 may also
be omitted in the sensing circuits. The sensing circuits may
provide similar capabilities for facilitating serial communications
within the group as described above.
[0072] FIG. 8 illustrates an example embodiment of a driver circuit
720. The driver circuit 720 includes a voltage pre-regulation
circuit 810, an Rx_Phy 820, a low dropout regulator 830, an
oscillator 840 control logic 850, a PWM dimming controller 870, a
PWM transistor 875, and a brightness control circuit 880. These
components operate similarly to the analogous components in the
driver circuit 420 of FIG. 5 except the Rx_Phy 820 is coupled to
receive commands via the dimming input pin 734 instead of via power
line communication. The power pin 724 supplies power without
modulated data.
[0073] FIG. 9 is an example circuit diagram of a control circuit
910 that may correspond to the control circuits 110, 210, 410, 610,
or 710 of any of the preceding embodiments. The control circuit 910
controls operation of the display device based on signals
communicated on control lines 915 as described above. The control
circuit 910 may include a timing controller 930 and a bridge 920.
The control circuit 910 may control the display device using either
active matrix (AM) or passive matrix (PM) driving methods.
[0074] The timing controller 930 generates an image control signal
915 indicating values for driving pixels of the display device and
timing for driving the pixels. For example, the timing controller
930 controls 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 controller 930 controls the brightness for
driving each of the LED zones during a given image or video frame.
The image control signal 915 is provided by the timing controller
930 to the bridge 920.
[0075] The bridge 920 translates the image control signal 915 to
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 bridge 920 may receive feedback
signals from the device array via the control lines 915 and adjust
operation accordingly as described in any of the preceding
embodiments.
[0076] FIG. 10A is a cross sectional view of a first embodiment of
a zone IC 1000 that includes an integrated LED and driver circuit
1005 in a single package. In the example shown in FIG. 10A, the
circuit 1000 includes a printed circuit board (PCB) 1010, a PCB
interconnect layer 1020, and the integrated LED and driver circuit
1005 which comprises a substrate 1030, a driver circuit layer 1040,
an interconnect layer 1050, a conductive redistribution layer 1060,
and an LED layer 1070. Bonded wires 1055 may be included for
connections between the PCB interconnect layer 1020 and the
integrated LED and driver circuit 1005. The PCB 1010 comprises a
support board for mounting the integrated LED and driver circuit
1005, the control circuit and various other supporting electronics.
The PCB 1010 may include internal electrical traces and/or vias
that provide electrical connections between the electronics. A PCB
interconnect layer 1020 may be formed on a surface of the PCB 1010.
The PCB interconnect layer 1020 includes pads for mounting the
various electronics and traces for connecting between them.
[0077] The integrated LED and driver circuit 1005 includes a
substrate 1030 that is mountable on a surface of the PCB
interconnect layer 1020. The substrate 1030 may be, e.g., a silicon
(Si) substrate. In other embodiments, the substrate 1030 may
include various materials, such as gallium arsenide (GaAs), indium
phosphide (InP), gallium nitride (GaN), AlN, sapphire, silicon
carbide (SiC), or the like.
[0078] A driver circuit layer 1040 may be fabricated on a surface
of the substrate 1030 using silicon transistor processes (e.g., BCD
processing) or other transistor processes. The driver circuit layer
1040 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 1050 may be formed on a surface of the driver
circuit layer 1040. The interconnect layer 1050 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 1050 may
include electrical traces to electrically connect the driver
circuits in the driver circuit layer 1040 to wire bonds 1055, which
are in turn connected to the control circuit on the PCB 1010. In an
embodiment, each wire bond 1055 provides an electrical connection
to the control circuit in accordance with the connections described
in any of the preceding embodiments.
[0079] In an embodiment, the interconnect layer 1050 is not
necessarily distinct from the driver circuit layer 1040 and these
layers 1040, 1050 may be formed in a single process in which the
interconnect layer 1050 represents a top surface of the driver
layer 1040.
[0080] The conductive redistribution layer 1060 may be formed on a
surface of the interconnect layer 1050. The conductive
redistribution layer 1060 may include a metallic grid made of a
conductive material, such as Cu, Ag, Au, Al, or the like. An LED
layer 1070 includes LEDs that are on a surface of the conductive
redistribution layer 1060. The LED layer 1070 may include arrays of
LEDs arranged into the LED zones as described above. The conductive
redistribution layer 1060 provides an electrical connection between
the LEDs in the LED layer 1070 and the one or more driver circuits
in the driver circuit layer 1040 for supplying the driver current
and provides a mechanical connection securing the LEDs over the
substrate 1030 such that the LED layer 1070 and the conductive
redistribution layer 1060 are vertically stacked over the driver
circuit layer 1040.
[0081] Thus, in the illustrated circuit 1000, the one or more
driver circuits and the LED zones including the LEDs are integrated
in a single package including a substrate 1030 with the LEDs in an
LED layer 1070 stacked over the driver circuits in the driver
circuit layer 1040. By stacking the LED layer 1070 over the driver
circuit layer 1040 in this manner, the driver circuits can be
distributed in the display area of a display device.
[0082] FIG. 10B is a cross sectional view of a second embodiment of
a display device 1080 including an integrated LED and driver
circuit 1085, according to one embodiment. The device 1080 is
substantially similar to the device 1000 described in FIG. 10A but
utilizes vias 1032 and corresponding connected solder balls 1034 to
make electrical connections between the driver circuit layer 1040
and the PCB 1010 instead of the wires 1055. Here, the vias 1032 are
plated vertical electrical connections that pass completely through
the substrate layer 1030. In one embodiment, the substrate layer
1030 is a Si substrate and the through-chip vias 1032 are Through
Silicon Vias (TSVs). The through-chip vias 1032 are etched into and
through the substrate layer 1030 during fabrication and may be
filled with a metal, such as tungsten (W), copper (C), or other
conductive material. The solder balls 1034 comprise a conductive
material that provide an electrical and mechanical connection to
the plating of the vias 1032 and electrical traces on the PCB
interconnect layer 1020. In one embodiment, each via 1032 provides
an electrical connection for providing signals such as the driver
control signal from the control circuit on the PCB 1010 to a group
of driver circuits on the driver circuit layer 1040. The vias 1032
may 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 layer 1070, and a path to a circuit ground
(GND).
[0083] FIG. 10C is a cross sectional view of a third embodiment of
a display device 1090 including an integrated LED and driver
circuit 1095. The device 1090 is substantially similar to the
device 1080 described in FIG. 10B but includes the driver circuit
layer 1040 and interconnect layer 1050 on the opposite side of the
substrate 1030 from the conductive redistribution layer 1060 and
the LED layer 1070. In this embodiment, the interconnect layer 1050
and the driver circuit layer 1040 are electrically connected to the
PCB 1010 via a lower conductive redistribution layer 1065 and
solder balls 1034. The lower conductive redistribution layer 1065
and solder balls 1034 provide mechanical and electrical connections
(e.g., for the driver control signals) between the driver circuit
layer 1040 and the PCB interconnect layer 1020. The driver circuit
layer 1040 and interconnect layer 1050 are electrically connected
to the conductive redistribution layer 1060 and the LEDs of the LED
layer 1070 via one or more plated vias 1032 through the substrate
1030. The one or more vias 1032 seen in FIG. 10C may be utilized to
provide the driver currents from the driver circuits in the driver
circuit layer 1040 to the LEDs in the LED layer 1070 and other
signals as described above
[0084] In alternative embodiments, the integrated driver and LED
circuits 1005, 1085, 1095 may be mounted to a different base such
as a glass base instead of the PCB 1010.
[0085] FIG. 11 is a top down view of a display device using an
integrated LED and driver circuit 2300, according to one
embodiment. The circuit 1100 can correspond to a top view of any of
the integrated LED and driver circuits 1005, 1085, 1095 depicted in
FIGS. 10A-10C. A plurality of LEDs of an LED lay 1070 is arranged
in rows and columns (e.g., C1, C2, C3, . . . Cn-1, Cn). For passive
matrix architectures, each row of LEDs of the LED layer 1070 is
connected by a conductive redistribution layer 1060 to 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 layer
1070 via the conductive redistribution layer 1060.
[0086] FIG. 12 illustrates a schematic view 1200 of several layers
of a display device with an integrated LED and driver circuit,
according to one embodiment. The schematic view includes the PCB
1010, the driver circuit layer 1040, the conductive redistribution
layer 1060, and the LED layer 1070 as described in FIGS. 10A-10C.
The schematic of FIG. 12 shows circuit connections for the circuits
1005, 1085, 1095 of FIGS. 10A-10C but does not reflect the physical
layout. As described above, in the physical layout, the LED layer
1070 is positioned on top of (i.e., vertically stacked over) the
conductive redistribution layer 1060. The conductive redistribution
layer 1060 is positioned on top of the driver circuit layer 1040
and the driver circuit layer 1040 is positioned on top of the PCB
1010.
[0087] The PCB 1010 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 1040 includes a
plurality of driver circuits (e.g., DC1, DC2, . . . DCn) and a
demultiplexer DeMux. The conductive redistribution layer 1060
provides electrical connections between the driver circuits and the
demultiplexer DeMux in the driver circuit layer 1040 to the
plurality of LEDs in the LED layer 1070. The LED layer 1070
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 1060 to one
driver circuit in the driver circuit layer 1040. 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 1060 to one output (e.g., VLED_1, VLED_2, . . . VLED_M) of
the demultiplexer DeMux in the driver circuit layer 1040. The
demultiplexer DeMux in the driver circuit layer 1040 is connected
to a power supply (VLED) and a control signal from the PCB 1010.
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 1070 is
activated when power (VLED) is supplied on its associated row and
the driver current is supplied to its associated column.
[0088] 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.
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