U.S. patent application number 16/662897 was filed with the patent office on 2021-04-29 for organic light emitting diode display compensation tool.
This patent application is currently assigned to Dell Products L.P.. The applicant listed for this patent is Dell Products L.P.. Invention is credited to Deeder M. Aurongzeb, Jong Seo Lee, Asim M. Siddiqui.
Application Number | 20210125538 16/662897 |
Document ID | / |
Family ID | 1000004440522 |
Filed Date | 2021-04-29 |
United States Patent
Application |
20210125538 |
Kind Code |
A1 |
Lee; Jong Seo ; et
al. |
April 29, 2021 |
ORGANIC LIGHT EMITTING DIODE DISPLAY COMPENSATION TOOL
Abstract
A portable information handling system integrated organic light
emitting diode (OLED) display presents a compensation image having
pixels illuminated at predetermined color and luminance settings.
The compensation image is captured by a external camera as a
calibration image and analyzed to compare pixel color and luminance
provided by the OLED display with expected color and luminance to
determine pixel compensation values that correct the OLED display
for presentation of a uniform visual image that reproduces an
intended visual image when the compensation values are applied at
presentation of visual images by the OLED display.
Inventors: |
Lee; Jong Seo; (Austin,
TX) ; Aurongzeb; Deeder M.; (Austin, TX) ;
Siddiqui; Asim M.; (Cedar Park, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dell Products L.P. |
Round Rock |
TX |
US |
|
|
Assignee: |
Dell Products L.P.
Round Rock
TX
|
Family ID: |
1000004440522 |
Appl. No.: |
16/662897 |
Filed: |
October 24, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G 3/2003 20130101;
G09G 2320/0666 20130101; G09G 3/3225 20130101; H04N 17/02 20130101;
G09G 2320/0693 20130101; H04N 9/44 20130101; G09G 2320/068
20130101; G09G 2380/02 20130101 |
International
Class: |
G09G 3/20 20060101
G09G003/20; G09G 3/3225 20060101 G09G003/3225; H04N 17/02 20060101
H04N017/02; H04N 9/44 20060101 H04N009/44 |
Claims
1. An information handling system comprising: a housing having
first and second housing portions rotationally coupled by a hinge;
a processor disposed in the housing and operable to execute
instructions to process information; a memory disposed in the
housing and interfaced with the processor, the memory operable to
store the instructions and information; a display integrated in the
housing and having plural organic light emitting diode (OLED)
pixels, the display operable to present visual images by
illuminating the OLED pixels based upon a pixel value; a graphics
processor interfaced with the processor and display, the graphics
processor operable to process the information to generate pixel
values that define visual images for presentation at the display; a
compensation image generator operable to present a compensation
image at the display having a predetermined luminance and color;
and a compensation engine stored in non-transitory memory and
having instructions that execute on the processor to receive a
camera image taken by an external camera, the camera image
capturing the display presenting the compensation image, the
instructions further comparing the camera image and the
compensation image to calibrate color and luminance presented at
the OLED pixels .
2. The information handling system of claim 1 wherein: the external
camera interfaces with the compensation image generator and the
compensation engine to coordinate the presentation of the
compensation image and capture of the camera image.
3. The information handling system of claim 2 wherein the
compensation image comprises alternating illumination of pixels
spaced between one or more pixels in an off state and the camera
image comprises a video captured over a predetermined time
period.
4. The information handling system of claim 3 wherein the
compensation image and video each include time stamps applied by
the compensation engine to associate pixel location and pixel
illumination.
5. The information handling system of claim 1 wherein the
compensation engine applies compensation values to pixel values
generated by the graphics processor to apply compensated pixel
values to the display that compensate for degradation at the
pixels.
6. The information handling system of claim 5 wherein the
compensation image generator provides pixel values to the display
without compensation by the compensation values and the
compensation engine determines a compensation to adjust the pixel
color and luminance to a predetermined value.
7. The information handling system of claim 5 wherein the
compensation image generator provides pixel values to the display
with compensation by the compensation values and the compensation
engine determines a compensation to adjust pixel color and
luminance based at least in part upon the compensation values.
8. The information handling system of claim 1 wherein each OLED
pixel includes a red, a green and a blue OLED material and the
compensation image generator presents compensation images having
only red OLED material illuminated, only green OLED material
illuminated and only blue OLED material illuminated.
9. The information handling system of claim 1 wherein the display
comprises a folded OLED film extending over opposing sides of the
first housing portion.
10. A method for compensating an information handling system
display presentation of visual images, the method comprising:
generating a compensation image at the display having a
predetermined luminance and color at each of plural organic light
emitting diode (OLED) pixels of the display; capturing a camera
image of the display presenting the compensation image, the
capturing performed by an external camera; comparing the
compensation image and the camera image to determine calibration
information that calibrates color and luminance presented at the
OLED pixels; and applying the calibration information to adjust the
color and luminance of the OLED pixels for presentation of content
as visual images.
11. The method of claim 10 further comprising: interfacing the
information handling system and the external camera; changing the
compensation image over time; and storing synchronizing information
with the camera image indicating the changing of the compensation
image.
12. The method of claim 10 wherein: the compensation image is
generated without application of the calibration information; and
the comparing determines a full difference between color and
luminance available from degraded pixels and color and luminance
available from compensated pixels.
13. The method of claim 10 wherein: the compensation image is
generated with application of the calibration information; and the
comparing determines a partial difference between color and
luminance as calibrated at the degraded pixels.
14. The method of claim 10 wherein the compensation image comprises
a video having alternating colors presented at the plural OLED
pixels and changing at a predetermined periodic interval.
15. The method of claim 10 wherein the comparing is performed at
the information handling system by communicating the camera image
from the external camera to the information handling system.
16. The method of claim 10 wherein the comparing is performed at
the external camera by communicating the compensation image from
the information handling system to the external camera.
17. The method of claim 10 wherein the calibration image comprises
a video having every other of the plural pixels illuminated in a
periodic manner.
18. The method of claim 10 wherein the calibration image comprises
a video having alternating red, green and blue pixel
illumination.
19. A portable information handling system comprising: a processor
operable to execute instructions to process information; memory
operable to store the information and instructions; a camera
interfaced with the processor and operable to capture an image of
an information handling system having an integrated organic light
emitting diode (OLED) display presenting a compensation image; a
communication medium operable to communicate with the information
handling system having the integrated OLED display; and a
non-transitory memory operable to store instructions that execute
on the processor to: retrieve through the communication medium a
compensation visual image presented at the OLED display; capture a
calibration picture of the OLED display with the camera; compare
color and luminance of the OLED pixels detected in the calibration
picture with color and luminance of the compensation visual image
to determine calibration information defining adjustments to pixel
values applied to the OLED display; and communicate the calibration
information through the communication medium.
20. The portable information handling system of claim 19 wherein
the compensation visual image comprises pixel luminance and color
at a greatest available setting.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] U.S. Patent Application No. ______, entitled "Organic Light
Emitting Diode Display Power Management Based on Usage Scaling" by
inventors Asim M. Siddiqui, Deeder M. Aurongzeb, and Jong Seo Lee,
Attorney Docket No. DC-116159.01, filed on even date herewith,
describes exemplary methods and systems and is incorporated by
reference in its entirety.
[0002] U.S. Patent Application No. ______, entitled "Organic Light
Emitting Diode Display Thermal Management" by inventors Jong Seo
Lee, Deeder M. Aurongzeb, and Asim M. Siddiqui, Attorney Docket No.
DC-116163.01, filed on even date herewith, describes exemplary
methods and systems and is incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0003] The present invention relates in general to the field of
portable information handling systems, and more particularly to an
information handling system organic light emitting diode display
compensation tool.
Description of the Related Art
[0004] As the value and use of information continues to increase,
individuals and businesses seek additional ways to process and
store information. One option available to users is information
handling systems. An information handling system generally
processes, compiles, stores, and/or communicates information or
data for business, personal, or other purposes thereby allowing
users to take advantage of the value of the information. Because
technology and information handling needs and requirements vary
between different users or applications, information handling
systems may also vary regarding what information is handled, how
the information is handled, how much information is processed,
stored, or communicated, and how quickly and efficiently the
information may be processed, stored, or communicated. The
variations in information handling systems allow for information
handling systems to be general or configured for a specific user or
specific use such as financial transaction processing, airline
reservations, enterprise data storage, or global communications. In
addition, information handling systems may include a variety of
hardware and software components that may be configured to process,
store, and communicate information and may include one or more
computer systems, data storage systems, and networking systems.
[0005] Portable information handling systems integrate processing
components, a display and a power source in a portable housing to
support mobile operations. Portable information handling systems
allow end users to carry a system between meetings, during travel,
and between home and office locations so that an end user has
access to processing capabilities while mobile. Tablet
configurations typically expose a touchscreen display on a planar
housing that both outputs information as visual images and accepts
inputs as touches. Convertible configurations typically include
multiple separate housing portions that rotationally couple to each
other so that the system converts between closed and open
positions. For example, a main housing portion integrates
processing components and a keyboard and rotationally couples with
hinges to a lid housing portion that integrates a display. In a
clamshell configuration, the lid housing portion rotates
approximately ninety degrees to a raised position above the main
housing portion so that an end user can type inputs while viewing
the display. In a tablet configuration, the housing portions rotate
360 degrees relative to each other to expose the display for touch
inputs while the keyboard is hidden at the bottom of the system.
After usage, convertible information handling systems rotate the
lid housing portion over the main housing portion to protect the
keyboard and display, thus reducing the system footprint for
improved storage and mobility.
[0006] Recently, portable information handling systems have begun
transitioning from integrating liquid crystal displays (LCDs) to
instead integrate organic light emitting diode (OLED) displays.
LCDs generate visual images by passing illumination from a
backlight through an array of pixels that filter red, green and
blue light. In contrast, OLED displays generate visual images by
creating illumination with direct current applied to red, green and
blue OLED material of each pixel. One advantage of OLED displays is
that generating visual images without a backlight tends to decrease
the thickness of the display panel. Another advantage of OLED
displays is that the display material integrates in a flexible film
that can fold over housing structures. One example system has an
OLED display film folded over a housing portion so that a display
surface presents visual images at opposing sides of the housing
portion. Another way that an OLED foldable display film integrates
in an information handling system is to fold at a hinge location so
that the display can present a flat tablet appearance with a
relatively large surface area or can fold in a clamshell position
to hold part of the display in a raised viewing position.
[0007] Although OLED display films offer increased flexibility for
integration of a display in a portable information handling system,
OLED display operations tend to introduce thermal and power
management challenges. Generally, OLED material creates greater
illumination by increasing current applied to the OLED material.
Applying different amounts of current to red, green and blue OLED
material of a pixel generates a unique color and luminance with
varied brightness of red, green and blue light resulting from each
OLED material. The different currents are scanned across OLED
pixels at a refresh rate applied by a timing controller (TCON) of
the display. The TCON sets the current levels based upon pixel
values defined by a graphics controller, which creates the pixel
values to define a visual image across the array of OLED pixels.
However, OLED material tends to degrade over time so that, as the
OLED pixels are used, different levels of current are needed to
create a desired illumination. To achieve a desired presentation of
visual images at an OLED display, a compensation table is typically
maintained that adjusts the amount of current applied at each pixel
for the degradation at each pixel. Degradation of OLED material in
each pixel is estimated based upon the type of visual images
presented by each pixel over time, such as the color and luminance
at each pixel. As a result of variations in current applied to
pixels to obtain desired illumination at each pixel, irregularities
in thermal distribution and power consumption can result. In
addition, degradation of OLED material can result in ghosting of
visual images at the display where compensation estimated over time
does not match the actual impact of OLED material degradation on
visual image creation.
[0008] Integration of OLED display films into a convertible
information handling system introduces additional challenges,
especially where the OLED display film is disposed on opposing
faces of the housing. For instance, the angle at which an end user
views the display may vary based upon the rotational orientation of
the rotationally coupled portable housing portions. In some
rotational orientations, some parts of the display surface may have
more prominent end user interactions than other parts. Further, as
the portable housing moves to varying lighting conditions, such as
with different ambient light characteristics, display color and
luminance may have to change to maintain a consistent appearance of
presented visual images for the end user. As display pixels respond
to varying conditions, thermal and power management difficulties
tend to arise, especially where display pixel compensation is less
accurate. In addition, image ghosting may become more distinct and
variable since thermal and power variations impact illumination
from OLED material in a variable manner as the OLED material
degrades.
SUMMARY OF THE INVENTION
[0009] Therefore, a need has arisen for a system and method which
manages power and thermal conditions at an organic light emitting
diode (OLED) display.
[0010] A further need exists for a system and method that adapts
compensation at an OLED display over time with measurements of
degradation at the OLED material.
[0011] In accordance with the present invention, a system and
method are provided which substantially reduce the disadvantages
and problems associated with previous methods and systems for
management of OLED display power, thermal and degradation
constraints. An OLED display is divided into plural zones of plural
pixels to present visual images in each zone with adjustments to
color and brightness that achieve desired power, thermal and
degradation constraints. Based upon various predetermined
conditions, pixels in different display zones may present visual
images with full or partial pixel density, base commanded or
reduced brightness, base commanded scan rate or reduced scan rate,
or other display zone individualized presentation parameters.
[0012] More specifically, an information handling system processes
information with a processor that executes instructions in
cooperation with a memory that stores the information and
instructions. A graphical processing unit further processes the
information to define visual images with pixel values that command
the color and luminance generated by application of current to OLED
material of each pixel. A display zone manager executing on the
information handling system, such as with embedded code stored in
non-transitory memory to execute on an embedded controller or
graphics processor, defines plural display zones of plural
contiguous OLED pixels at the display based upon one or more
predetermined conditions, such as power constraints, thermal
constraints and/or OLED material preservation. Based upon the
detected condition, pixels of a display zone have illumination
adjusted to achieve power, thermal and/or OLED material
preservation goals. As an example, a display zone that presents
passive or background content is adjusted to generate visual images
with a partial pixel density while a display zone with active
content is presented with full pixel density. For instance, partial
pixel density places at least some OLED pixels in the display zone
in an off state to reduce power consumption and thermal energy
generation without undue impact on visual image presentation while
full pixel density presents visual images at a base commanded color
and luminance. As another example, a pixel refresh rate is reduced
in a display zone having a static or passive content to reduce
power consumption and thermal energy release. In one embodiment,
compensation values that adjust current applied to OLED material in
pixels are validated by comparing a compensation image presented by
the OLED display against a camera picture image captured of the
display.
[0013] The present invention provides a number of important
technical advantages. One example of an important technical
advantage is that an OLED display adapts to present visual images
at different display zones to achieve power, thermal and OLED
material preservation objectives. By adjusting pixel density,
refresh rate and other visual image presentation parameters in
passive content display zones, power consumption, thermal energy
release and OLED material degradation may be reduced. Graduated
adjustments at passive content display zones provide adjustments
that have minimal impact on the end user experience and in an
imperceptible manner. Visual image compensation, which impacts
power and thermal constraints as well as image ghosting, is updated
by capturing a picture with an external camera of a defined
compensation image to compare the base commanded visual image
applied to the display with the actual illumination presented by
the display so that compensation values adjust to present more
accurate representations of based commanded visual images without
ghosting effects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention may be better understood, and its
numerous objects, features and advantages made apparent to those
skilled in the art by referencing the accompanying drawings. The
use of the same reference number throughout the several figures
designates a like or similar element.
[0015] FIG. 1 depicts an exploded view of a convertible information
handling system having a folded organic light emitting diode (OLED)
display disposed over a housing portion to present visual images at
opposing sides of the housing portion;
[0016] FIG. 2 depicts a block diagram of an information handling
system configured to manage power and thermal constraints related
to OLED display presentation of visual images;
[0017] FIG. 3 depicts a flow diagram of a process for adjusting
visual image presentation to achieve power and thermal management
objectives;
[0018] FIG. 4 depicts a flow diagram of a control process for
adjusting power applied for presentation of visual images based
upon housing rotational orientations;
[0019] FIG. 5 depicts an example of an OLED display with display
zones having content and power management configurations;
[0020] FIG. 6 depicts a flow diagram of a process for managing
information handling system skin temperature by adjusting display
zone pixel illumination;
[0021] FIG. 7 depicts a flow diagram of a process for managing
presentation of ghost images at an OLED display by adjusting color
presented at the display; and
[0022] FIG. 8 depicts a flow diagram of a process for adjusting
thermal and or power constraints associated with an OLED display by
adjusting perceived brightness at the display.
DETAILED DESCRIPTION
[0023] An organic light emitting diode (OLED) display in a portable
information handling system adapts power and thermal management to
operating conditions with measured adjustments to OLED material
degradation over time. For purposes of this disclosure, an
information handling system may include any instrumentality or
aggregate of instrumentalities operable to compute, classify,
process, transmit, receive, retrieve, originate, switch, store,
display, manifest, detect, record, reproduce, handle, or utilize
any form of information, intelligence, or data for business,
scientific, control, or other purposes. For example, an information
handling system may be a personal computer, a network storage
device, or any other suitable device and may vary in size, shape,
performance, functionality, and price. The information handling
system may include random access memory (RAM), one or more
processing resources such as a central processing unit (CPU) or
hardware or software control logic, ROM, and/or other types of
nonvolatile memory. Additional components of the information
handling system may include one or more disk drives, one or more
network ports for communicating with external devices as well as
various input and output (I/O) devices, such as a keyboard, a
mouse, and a video display. The information handling system may
also include one or more buses operable to transmit communications
between the various hardware components.
[0024] Referring now to FIG. 1, an exploded view of a convertible
information handling system 10 depicts a folded organic light
emitting diode (OLED) display 36 disposed over a housing portion 16
to present visual images at opposing sides of the housing portion.
In the example embodiment, convertible information handling system
10 is built into a portable housing 12 having a main housing
portion 14 and lid housing portion 16 rotationally coupled with a
hinge 18. For instance, housing 12 rotates from a closed position
having lid housing portion 16 proximate to main housing portion 14
to a clamshell position having lid housing portion 16 raised
substantially perpendicular to main housing portion 14. In one
embodiment, housing 12 rotates to a tent position having
approximately 270 degrees of rotation and a tablet position having
a full 360 degrees of rotation. At the varied rotational
orientations, folded OLED display film 36 has different display
surfaces exposed at different orientations relative to the end user
and varied ambient conditions, such as external lighting and the
external environment for thermal rejection. That is, as lid housing
portion 16 raises away from main housing portion 14, greater
surface exposure to external conditions improves thermal rejection
for folded OLED display 36. In one alternative embodiment, a second
folded OLED display film 36 may be disposed over main housing
portion 14 to act as a display and input/output device, such as by
presenting a virtual keyboard to accept key input values.
[0025] Information handling system 10 processes information with
processing components disposed in main housing portion 14. The
example embodiment depicts a motherboard 20 coupled to main housing
portion 14 to support and interface the processing components, such
as through wirelines of a printed circuit board. A central
processing unit (CPU) 22 couples to motherboard 20 and interfaces
with random access memory (RAM) 24 to execute instructions that
process information, with the instructions and information stored
in RAM 24. A chipset 26 interfaces with CPU 22 to manage CPU clock
and communication functions. A graphics processor unit (GPU) 28
interfaces with CPU 22 to accept information for presentation at
folded OLED display 36 and process the information into pixel
values that define color and luminance of pixels of folded OLED
display film 36, as is described in greater detail below. An
embedded controller (EC) 30 manages operation of physical
components on motherboard 20, such as for application of power and
thermal transfer systems. A solid state drive (SSD) 32 stores
information in non-transitory flash memory or other persistent
storage to retain the information during periods of no power. For
example, SSD 32 stores an operating system and applications that
execute on CPU 22 to process information that generates visual
images at folded OLED display film 36. A wireless network interface
card (WNIC) 34 interfaces with CPU 22 to support network
communications, such as wireless local area network (WLAN)
communications like WiFi and wireless personal area network (WPAN)
communications like Bluetooth. In some example embodiments, WNIC 34
may support wired communications as may a USB or similar cable
port.
[0026] Folded OLED display film 36 interfaces with GPU 28 to accept
pixel values for presentation as visual images. In the example
embodiment, folded OLED display film 36 folds over top of lid
housing portion 16 to expose a display surface on opposing sides of
lid housing portion 16. A camera 39 is aligned to capture pictures
of visual images facing the display surfaces, such as to support
video conferencing. In various embodiments, folded OLED display
film 36 presents various types of visual images, typically based
upon end user selections and preferences. An active content window
38 presents information selected by the end user to interact with
inputs made by the end user, such as through a keyboard or mouse.
In alternative embodiments, the end user may select active content
window 38 to expand for presentation of visual information across
the entire display surface. In the example embodiment, a passive
content window 40 presents other visual images that are not
actively associated with end user inputs. In a typical use
environment, passive content window 40 presents information of an
application instance as a background under active content window 38
that an end user may select with a mouse click to bring the
information into focus to accept inputs so that the end user can
rapidly change between applications and/or application instances. A
background visual image 42 presents a default image where other
content is not selected, such as a screensaver, wallpaper or
default color. A tool bar 44 with a variety of tool icons 46 are
presented along the bottom edge of OLED display film 36, such as
quick start icons for applications and operating system
functions.
[0027] Referring now to FIG. 2, a block diagram depicts an
information handling system 10 configured to manage power and
thermal constraints related to OLED display presentation of visual
images. A hardware layer 52 includes hardware components that
cooperate to process and present information as visual images. For
example, CPU 22 executes instructions that create visual
information, which GPU 28 further processes into pixel values that
define a visual image. The pixel values are provided to a timing
controller (TCON) 50, which scans the pixel values for application
at OLED display 36. The example embodiment depicts OLED display 36
as having plural pixels 60 disposed under a cover glass 58 in an
array of pixel columns 68 and pixel rows 70. Each pixel 60 includes
red OLED material 62, blue OLED material 64 and green OLED material
66. TCON 50 scans pixel values across pixel columns 68 and along
pixel rows 70 to apply current at each of red, blue and green
materials so that a color of a commanded brightness results at each
pixel. The scan of pixel values takes place at a refresh rate that
creates a visual image so that an end user cannot detect changes
over time. For instance, a scan refresh rate of approximately 60 Hz
will typically support a moving visual image without an end user
perceiving the changing pixels due to changes in pixel values, such
as can show up in ghosts of moving images. Lower scan refresh rates
of as low as 10 Hz may provide a satisfactory image quality where
movement is minimal. Thermal sensors 88 are disposed within display
36 to monitor thermal conditions related to the presentation of
visual images and report the thermal conditions to embedded
controller 30. Since OLED material generates illumination through
dissipation of power, thermal conditions may vary across display 36
depending upon the color and luminance generated at each pixel. An
angle sensor 48 detects relative rotational orientation of housing
portions of information handling system 10. Angle sensor 48 may be
a Hall sensor or other physical device that monitors hinge
position, or a set of accelerometers that measure orientation of
the housing portions relative to gravity.
[0028] Information handling system 10 includes a firmware layer 54
having embedded code stored in non-transitory flash memory to
execute on processing components of hardware layer 52. For example,
firmware embedded code is installed and managed as drivers by an
operating system 78 of a software layer 56. A power manager 72
executes on embedded controller 30 to monitor power use of hardware
layer 52. For example, power manager 72 coordinates application of
power available from a charger at variable levels demanded by CPU
22 based upon availability of battery charge and/or an external
power source. A display zone manager 74 monitors operating
conditions at information handling system 10 to define plural
display zones of contiguous pixels 60 of display 36 for management
of visual image presentation as is addressed in greater detail
below. For instance, display zone manager 74 executes on CPU 22,
GPU 28 and embedded controller 30 to define display zones based
upon presented content, environmental conditions, housing position,
power consumption and thermal conditions. A compensation table 76
stored in non-transitory memory includes compensation values for
pixels 60 that adjust pixel values based upon degradation of OLED
material over time. The compensation values are estimated based
upon the response of the OLED material to current, such as with
periodic calibration processes, and based upon tracking of images
presented at display 36 and known degradation characteristics. For
instance, blue OLED material tends to degrade more quickly than red
and green OLED material. The compensation values may be applied by
various hardware components, such as GPU 28 or TCON 50, so that
pixels 60 have current applied to generate an intended color and
brightness instead of a degraded color and brightness that would
result from application of a base uncompensated pixel value.
[0029] Software layer 56 includes an operating system 78, such as
WINDOWS, that provides logical interfaces for applications to
access resources of firmware layer 54 and hardware layer 52. For
example, operating system 78 includes a display driver 80 having
embedded code distributed as firmware to interact with GPU 28 for
control of operation of display 36. For example, display driver 80
accepts display settings 82, such as from a display control panel
of operating system 78, and applies the display settings through
GPU 28 for effect at display 36. For example, end user color,
contrast and brightness display settings are applied by display
driver 80 to determine a base value for pixels 60, such as what
would be used by a liquid crystal display that does not experience
pixel material degradation. Once GPU 28 determines the base pixel
values, each pixel value is further compensated based upon
compensation values of compensation table 76 to present the desired
image with display 36 at its degraded pixel state. In addition to
other applications, software layer 56 includes a compensation image
generator 84 and a compensation engine 86. As is described in
greater detail below, compensation image generator 84 creates a
compensation image for presentation on display 36 that presents
defined pixel values for a calibration process by compensation
engine 86 to update compensation values of compensation table
76.
[0030] In operation, display zone manager 74 monitors power,
thermal and other conditions at information handling system 10 to
adjust visual images presented at display 36 to achieve desired
presentation, power and thermal constraints. Display zone manager
74 divides display 36 into plural display zones that each have
plural contiguous pixels based upon conditions detected at display
36. As one example, display zones may be defined to include pixels
that present active content as one display zone, passive content as
another zone, background as another display zone and a tool bar as
another display zone. In another example embodiment, display zone
manager 74 defines display zones based upon rotational orientation
of housing portions and the relative position of display 36 to an
anticipated position of an end user. For instance, a display
portion folded on a housing portion that is rotated to have one
surface towards an end user and the other hidden may be divided
into first and second zones based on orientation with additional
zones defined based on content as described above. In one
alternative embodiment, display zone manager 74 defines zones based
upon thermal conditions detected by thermal sensors 88, such as by
identifying portions of display 36 that have nonuniform temperature
distributions. In another alternative embodiment, display zones may
be defined based upon degradation and associated compensation
values, such as to provide degradation leveling on a zone basis
while achieving thermal and/or power management constraints. In
various alternative embodiments, different types of display zones
of varying size and dimensions may be defined to achieve desired
control so that pixels 60 in each defined display zone are
individually managed to achieve the desired control.
[0031] Once display zone manager 74 defines display zones to
achieve a desired objective, adjustments defined by display zone
manager 74 are applied at each pixels of each display zone by GPU
28, such as with alterations to compensation table 76 that include
the adjustments. Pixels in an active display zone present visual
images at a full density, meaning that the pixels all illuminate at
a base compensated value that generates a visual image as commanded
from the operating system and corrected by the compensation values
of compensation table 76. Pixels in non-active display zones
present visual images with a partial pixel density, meaning that
some of the pixels, such as half, illuminate at the based
compensated pixel value while the rest of the pixels apply an
adjusted pixel value, such as an off state, a reduced brightness
state or a reduced refresh rate state. In one example embodiment,
power management is achieved by reducing power drawn by pixels 60
in display zones having less demanding display constraints. For
instance, in a display zone associated with a passive content or
background, power is reduced by placing at least some of the pixels
60 into an off state having no current applied. Alternatively, some
of the pixels may have a reduced brightness that uses less current
or a reduced refresh rate, which also decreases power consumption.
In an Ultra High Definition (UHD) display having 4,000 (4K) pixels,
applying an off state, reduced brightness or reduced refresh rate
at every other pixel along a scan will decrease power consumption
with minimal impact on the presentation of visual images. For
example, an active content display zone may present visual images
with all pixels at the base compensated pixel values while a
background display zone presents a background visual image with
every other pixel illuminated so that the overall presentation of
visual images has a minimal and even imperceptible impact on the
end user experience. Within the display zone, the pixels 60
selected for the off state may alternate so that degradation across
the display zone pixels has an even impact over time. In some
embodiments, the partial pixel density may include more than half
or less than half of the pixels in the display zone.
[0032] Another example of an objective associated with defined
display zones is a thermal objective. As OLED material dissipates
power to generate illumination, excess thermal energy created with
the illumination results in an increase to the skin temperature of
information handling system 10, which generally must be rejected to
the external environment to avoid excessive skin temperatures.
Within an OLED display film, the thermal energy generated at
different pixels may vary substantially depending upon the color
and brightness of each pixel. Display zone manager interfaces with
thermal sensors 88 to detect thermal conditions and adjust power
applied in display zones to achieve a desired thermal constraint,
such as a uniform thermal distribution across the display. For
instance, if a housing orientation places a display portion out of
end user view as determined by angle sensor 48, a change to the
refresh rate in the hidden display zone can increase or decrease
thermal energy released by the pixels of the display zone. Since
the current applied at a pixel, and thus the thermal energy
released, varies depending upon compensation applied to the pixel
from the compensation table, the compensated value is used to
determine thermal management. As an example, a convertible
information handling system having a folded OLED display disposed
on opposing sides of a housing portion may apply visual images on a
hidden display zone that improves the uniformity of thermal
distribution as an adjustment to thermal release at an active
display zone on the opposing side of the housing portion.
[0033] In various embodiments, partial pixel densities in a display
zone may be applied in various ways that help to minimize the
impact on an end user experience and improve the life of OLED
material. As one example, blue pixel illumination is reduced in a
passive or background content display zone by gradually
transitioning blue out of the pixels to increase the presentation
of green illumination. For instance, a timer is referenced while
the pixel values are gradually changed to remove blue OLED material
illumination and, in one example embodiment, replace blue
illumination with green illumination. For example, a color shift of
approximately 2% is applied gradually in a manner that the end user
would have difficulty perceiving. When the shift from blue to green
illumination is applied in a passive display zone, the end user
impact is negligible and may instead help to emphasize the active
display zone, which continues to present base compensated pixel
values. As an alternative, blue illumination may take place at a
lower refresh rate, which applies less wear on the blue OLED
material. In another example embodiment, a display zone may have
overall brightness diminished gradually over time, such as by
reference to a timer that gradually decreases illumination at a
rate not perceptible to an end user. In one embodiment, the gradual
change in brightness, color or refresh rate may be supported in
part with eye tracking or other sensors that determine end user
focus on content display zones and passive display zones.
[0034] Compensation image generator 84 and compensation engine 86
cooperate to provide a measured update to compensation table 76
that provides more accurate and meaningful thermal and power
management. Compensation values of compensation table 76 are
applied to adjust current applied to pixels based upon degradation
of OLED material, and the applied current relates not only to the
illumination that is created but also to the power consumed and
thermal energy released by the illumination. To provide a
measurement of actual compensation needed at display 36 to achieve
a uniform visual image presentation, compensation image generator
84 creates a visual image for presentation at display 36 with
defined compensation values. An external camera captures a picture
visual image of the compensation image at display 36 and provides
the capture picture to compensation engine 86 for a comparison of
the displayed pixel illumination against the expected illumination
of the compensation image so that a measured compensation can be
determined. For example, a camera 39 integrated within an external
information handling system, such as portable telephone, captures
the picture of the compensation image and communicates the picture
to the compensation engine. Alternatively, the external information
handling system that captures the compensation engine may retrieve
the compensation image to it to perform compensation analysis and
return compensation values to the information handling system that
presented the compensation image. Compensation image generator 84
may command a uniform full power pixel illumination and measure
compensation based upon actual illumination difference to the full
power illumination. Alternatively, compensation image generator 84
may present a compensation image having compensation values of
compensation table 76 applied so that an error that exists in the
compensation values will show as a nonuniform visual image.
[0035] In one example embodiment, compensation engines 86 operating
on information handling system 10 and an external camera system
coordinate to aid in the accuracy of the compensation value
measurement. For instance, a difference between a presented image
pixel and a picture image pixel is used to determine the difference
between what GPU 28 commands for illumination at display 36 and
what illumination is actually produced. A typical external camera
captures 10 or more megapixels in a visual image so that each pixel
60 of a compensation engine can be analyzed across multiple pixels
of the picture captured of display 36; however, when pixels in
proximity to each other both illuminate, light may bleed between
the pixels so that the accuracy of analysis of the compensation
image. To help isolate pixels 60 during presentation of a
compensation image, compensation image generators 84 at the
presenting and capturing systems may synchronize changes to the
compensation image over time with time stamps to aid analysis with
capture images. For instance, the compensation image may include a
video having alternating pixels in an off state and transitioning
at time stamps to an on state while illuminating pixels transition
to an off state. As an alternative, each pixel color may illuminate
separately with alternating red, green and blue pixels so that each
pixel's material for each color is separately measured and the
different colors help to separate illuminated pixels for analysis.
In one embodiment, a wireless communication between the systems
provides a live feed of captured pictures to the compensation
engine so that a real time command of changes to compensation image
generator may adjust the compensation image as satisfactory visual
images for comparison are captured.
[0036] Referring now to FIG. 3, a flow diagram depicts a process
for adjusting visual image presentation to achieve power and
thermal management objectives. The process starts at step 90 with
definition of plural display zones at the display. As described
above, the display zones may be defined to achieve various
objectives based on system configuration and content presentation.
At step 92, monitoring is performed for power and thermal
conditions that are subject to management by adjustments is display
presentation of visual images. For instance, a low battery charge
might initiate a power saving constraint. Similarly, a skin
temperature nonuniform condition may initiate a thermal management
constraint. At step 94, a determination is made of whether a
thermal or power condition is detected that is associated with an
adjustment to visual image presentation at the display. If not, the
process returns to step 92 to continue monitoring for power and
thermal conditions. If a thermal or power condition is detected,
the process continues to step 96 to present visual images at the
display zones with power and/or thermal adjustments, such as are
described above or in greater detail below.
[0037] Referring now to FIG. 4, a flow diagram depicts a control
process for adjusting power applied for presentation of visual
images based upon housing rotational orientations. The process
starts at step 98 and initiates at step 100 with transition of the
information handling system from an off state or standby state
having the display idle. At step 102, the display screen
transitions to an on state to present visual information with all
display zones enabled. At step 104, the process waits for end user
selection of display zone management based upon housing rotational
orientation. In one example embodiment, display zones enable
automatically based upon detected housing rotational orientation
angles, although alternative embodiments may use other conditions
to initiate display zones, such as power or thermal states.
Alternatively, display zones may remain inactive until selected by
an end user. At step 106, a determination is made of whether
display zones are enabled and, if so, the process continues to step
108. If display zones are not enabled, the process returns to step
102 to continue monitoring conditions.
[0038] At step 108, display zones are enabled. In one embodiment,
display zones are predefined, such as by grouping predetermined
contiguous pixels based upon detected rotational orientation. In an
alternative embodiment, display zone boundaries are defined as
display zones are enabled and updated as conditions change, such as
power and thermal conditions. For instance, display zones seeking
to manage power consumption might change boundaries as selected
content changes; and display zones seeking to manage thermal
conditions might change boundaries as thermal uniformity across the
housing skin changes. At step 110, the timing controller is
provided with the display zones by the display driver through the
graphics processor, and at step 112 the variations in illumination
for each display zone are applied based upon the detected housing
rotational orientation. At step 114, the display screen
presentation of visual images is adjusted in each display zone
based upon viewing angle by using the graphics processing unit
three dimensional look up table of display compensation values. As
described above, various embodiments may enforce different display
zone logic to achieve different display objectives. In some
embodiments, the timing controller and graphics processing unit
cooperate to apply adjusted pixel values in an efficient manner
that avoids disruption of presented visual images. The process then
returns to step 108 to continue monitoring the display zone
configuration.
[0039] At step 108, if the process detects a condition or command
to cease the use of display zones, the process continues to step
116 to disable the selected display zones. At step 118, the process
retrieves the default display screen lookup table values and
applies those values to the display visual image. The process then
continues to step 114 to adjust display operations based upon
rotational orientation and the default display settings. In
alternative embodiments, adjustment of the display to default
settings may impact other power and thermal management processes.
For instance, transition to default display logic may increase
power draw and display zones having partial pixel density return to
full pixel density that has increased power consumption and thermal
release.
[0040] Referring now to FIG. 5, an example of an OLED display 36
depicts display zones 120 having content window 38 and power
management configurations. In the display zone 120 having content
window 38, visual images are presented with the base compensated
pixel values provided from the graphics processor. That is, content
window 38 is presented with visual qualities selected by the end
user through display settings and adjusted by compensation values
to correct for OLED material degradation. The base compensated
visual images present content window 38 with visual characteristics
intended by the end user. In the example embodiment, power
management is provided at a display zone 120 presenting background
42 visual images. The background 42 visual image has a partial
display density with every other pixel placed in an off state to
reduce power consumption without excessive impact on visual
quality. In one example embodiment, the off state is enforced by
the timing controller by cutting off current to the off state
pixels. Periodically, the timing controller shifts the on pixels to
an off state and the off pixels to an on state to encourage level
degradation of the OLED material. In alternative embodiments, other
types of adjustments may be applied, such as using decreased pixel
brightness instead of an off state or scanning a refresh at only
the pixels in the on state. In an alternative embodiment that
addresses thermal management, pixels may be selected for the on
state and off state based upon thermal conditions at the
information handling system where the off state will reduce thermal
release by display 36 and the on state will increase thermal
release.
[0041] Referring now to FIG. 6, a flow diagram depicts a process
for managing information handling system skin temperature by
adjusting display zone pixel illumination. The process starts at
step 122 and continues to step 124 to retrieve a temperature zone
map of the information handling system housing skin temperatures,
such as based upon temperatures sensed by thermal sensors disposed
around the housing. At step 126, a determination is made of whether
any portions of the temperature zone map are too hot. The thermal
constraint may be an absolute maximum temperature or may be a
nonuniform temperature condition having too large of a thermal
gradient across the display. For instance, disparate temperature
distributions can impact the quality of illumination presented
across a visual image as OLED material responds differently at
different temperatures. If the thermal constraints are not
exceeded, the process continues to step 130 to operate the display
in a base mode, step 132 to update the time, and then to step 124
after a predetermined delay, such as 60 seconds. If at step 126 the
temperature is too high, the process continues to step 128 to
adjust the display refresh rate and update the lookup table for
compensation that will provide a uniform brightness at the detected
thermal conditions and refresh rate. In various embodiments,
refresh rate may be adjusted across the entire display or in an
individualized manner in separate display zones to target a desired
thermal state. The process returns to step 124 after a 60 second
delay to continue monitoring the thermal state until the base. In
alternative embodiments, alternative illumination of display pixels
may be applied to manage thermal conditions. For example, a partial
pixel density may be used that changes the ratio of pixels on
versus off so that a thermal state of the display is achieved.
[0042] Referring now to FIG. 7 a flow diagram depicts a process for
managing presentation of ghost images at an OLED display by
adjusting color presented at the display. In particular, some parts
of the display, such as the tool bar, tend to show the same image
for an extended time period, such as a trash or quick start icons,
so that OLED material degradation can cause the image to ghost on
the display even when not selected. To minimize the impact of
static images, a timer and estimate of end user activity level
applied to gradually transition from a base or commanded color to
an off color that offsets the ghosting. The process starts at step
134 and determines if a desktop user application programming
interface (API) is active at step 136 or a static desktop is
presented at step 138. If so, the process continues to step 140 to
rearrange pixel coloration. Generally, blue OLED material tends to
degrade at a more rapid rate than other colors so that pixel
coloration will typically bias away from blue and towards red or
green, although pixel color may bias towards blue in some
instances. At step 142, the selected color is faded in small
increments that make the changes in appearance to the visual images
imperceptible to an end user, such as increments of 10% or even 2%.
At step 144 the look up table referenced by the graphics processor
and/or timing controller is set to maintain the selected color and
the process ends at step 146. In the example embodiment, color fade
may be managed over a display as a whole, a display zone or a
particular image, such as an icon.
[0043] Referring now to FIG. 8, a flow diagram depicts a process
for adjusting thermal and or power constraints associated with an
OLED display by adjusting perceived brightness at the display. The
process seeks to enforce adjustments to presentation of visual
images for thermal, power and other considerations in a manner
imperceptible to an end user. Based upon an end user's
interactions, such as end user proximity, gaze and inputs at I/O
devices, display refresh rates, contrast settings and brightness
are adjusted gradually over time. Although contrast is typically
defined as white and black levels in a display visual image,
however, blue, red and green color mixtures also give high
contrast. Selectively allocating these colors at OLED pixels will
adapt contrast while offering reducing blue OLED material
degradation and decreasing power consumption. Based upon end user
position and selected content, as the user defocuses a low refresh
rate change to a high refresh rate adapts the visual image to the
contrast change. The process starts at step 148 with sensor
detection of the end user eye and/or pupil movement to indicate the
portion of the display in focus. At step 150, visual perception of
an end user to changes in visual image presentation are determined
as a function of time and image brightness. Applying the time and
brightness function, at step 152, pixel color allocation is
adjusted to minimize usage of blue pixels gradually over time while
the image remains static. At step 154, brightness is controlled
from a high value to a lower value gradually over time in a manner
imperceptible to the end user. In the example graph 156, the
changes to color and brightness implemented gradually over time are
depicted for an example embodiment that performs changes in
brightness and color contrast in increments over time. Generally,
adjustments to display visual image presentation as described above
with respect to power and thermal management may also be performed
in this graduated manner for display zones.
[0044] Although the present invention has been described in detail,
it should be understood that various changes, substitutions and
alterations can be made hereto without departing from the spirit
and scope of the invention as defined by the appended claims.
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