News Column

Patent Application Titled "Circuit to Adjust Backlighting for a Display Device" Published Online

May 8, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventor Bork, Stephan (Murphy, TX), filed on October 14, 2012, was made available online on April 24, 2014.

No assignee for this patent application has been made.

Reporters obtained the following quote from the background information supplied by the inventors: "Today electronic devices like smartphones or tablet computers leverage a dedicated sensor to measure ambient light. The output of such ambient light sensors (ALS) is often used to adjust the back light of the display to save power (when there is a lot of ambient light the backlight has to be increased, where there is little ambient light the back light can be tuned down a bit).

"An ambient light sensor is a sensor used to detect the amount of ambient light available for a given purpose. Small display devices 100 usually have a desired goal of saving power, and if there is adequate ambient light available for the user to see the display, power may be saved by cutting back or eliminating the amount of backlighting used for these display devices 100. However, when the ambient light is low, the amount of backlighting should he increased in order to allow the user to easily view the screen. However, the direction of the ambient light is also important. One of the best directions for ambient light is where the ambient light from the light source 103 (as seen in FIG. 2) is directed over the shoulder of the user directly onto the display device. Under these circumstances, the ambient light is directly shining on the display device 100, and the ambient light does not interfere with the user. One of the worst directions for the ambient light from a light source 103 (as shown in FIG. 1) is behind the display device 100 which may cast a shadow preventing the user from adequately seeing the display device

"Under these circumstances, the ambient light does interfere with the user. Under both circumstances, the amount of ambient light may be the same, but the need for backlighting of the display device may be totally different. As a consequence, there is a need for a more accurate way to measure the need for backlighting of the display device.

"Ambient-light sensor (ALS) ICs are increasingly used in a variety of display and lighting applications to save power and improve the user experience. With ALS solutions, system designers can automatically adjust display brightness based on the amount of ambient light, Since backlighting accounts for a significant portion of the system's power budget, dynamic brightness control can translate into substantial power savings. It can also improve the user experience, allowing screen brightness to be optimized based on ambient-light conditions.

"Implementing such a system as shown in FIG. 3 requires three sections: a light sensor 105 to monitor the amount of ambient light, a device 107 (usually a microcontroller) to process the data, and an actuator 109 to control the current through the backlight 111.

"The second part of this control scheme involves actuating changes in backlighting on the screen. This can be done in many ways, depending upon the screen module used in the application. Two of the simplest ways are directly via a pulse-width modulation (PWM) scheme or indirectly by using a screen controller chip.

"Many display modules now have an integrated controller, which allows the user to directly set brightness by sending serial commands to the device. If this is not available, however, a simple backlight control actuator can be implemented by controlling the power delivered to a series of white LEDs behind the screen, which provide backlighting. One crude way of implementing this is by directly placing a FET in series with the LEDs and switching it on and off quickly using a PWM signal (FIG. 5).

"It is best not to jump directly from one setting to another: rather, the backlight brightness should be ramped up and down smoothly to ensure a seamless transition between levels

"This is best done by using timed interrupts with either a fixed or variable brightness step size to gradually shift either the PWM value used to control the current through the LEDs or the serial command sent to the display controller chip. FIG. 8 provides an example of such an algorithm. The prior art is limited since the ambient light sensor senses the light falling on the sensor, not the ambient light that shines in the users eye. Also the prior art requires a dedicated sensor hardware that adds cost to the electronic device.

"U.S. Pat. No. 7,796,784 discloses a plurality of iris codes being registered for each registrant in an iris database together with pupil diameter-iris diameter ratio R. At the time of authentication, an iris code is obtained from a captured iris image by feature extraction while pupil diameter-iris diameter ratio R is obtained. Ratio R obtained at the time of registration and ratio R obtained at the time of authentication are compared to specify an appropriate iris code from the iris database as an item to be collated before authentication.

"U.S. Pat. No. 7,076,087 discloses that both a forehead and a cheek are made in close contact to an eye position fixing portion, and a space defined between a left eye and a pinhole is shielded from extraneous light. When light derived from a room lighting device is entered into a right eye, a diameter of a pupil of the left eye is defined in a self-definition manner due to an interlocking characteristic of a living body, and then, a width of an iris 3 may be secured under stable condition. While infrared light is illuminated from a button lighting device onto this left eye, this illuminated left eye is photographed by an image pick up unit, and then, feature information as to the photographed left eye is compared with registered feature information in an individual identifying unit so as to execute an individual identification operation.

"US patent application 20030012413 discloses iris identification apparatus for performing personal identification by way of a shot iris image, and a plurality of images are shot by using a camera whose quantity of a visible light included in an illuminating light irradiated onto a person to be shot differs from each other. The presence of a variation in the pupil diameter in the plurality of iris images is determined by a pupil size comparison processor. In case a variation in the pupil diameter is determined, personal identification by an iris identification processor based on any one of the plurality of iris images. Preferably, light emitting diodes for emitting a green light as a source of a visible light are used.

"US patent application 20030002714 discloses a forehead and a cheek being made in close contact to an eye position fixing portion, and a space defined between an eye and a pinhole is shielded from extraneous light, and an iris is illuminated by infrared light of a lighting device. At this time, since a pupil diameter is defined in a self-control manner by receiving visible light of another lighting device, and also, a width of the iris is secured under stable condition, this iris is focused via the pinhole onto an image pick up element so that the iris can be photographed. Then, the acquired feature information of the iris is compared with registered feature information in order to execute the individual identifying operation.

"The above patents and patent applications are incorporated by reference in their entirety."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventor's summary information for this patent application: "A display device to measure ambient light brightness may include a camera to provide an image, a controller to detect a face from the image and to measure brightness from a ratio of the iris diameter to the pupil diameter D.sub.I/D.sub.P, and an actuator to stepwise change the backlighting of the display device based upon the measured brightness.

"The controller may turn off the display device if a face is not detected.

"The measured brightness may be compared with respect to a predetermined brightness.

"The actuator may change the backlighting of the display device if the measured brightness is more than two increments from the predetermined brightness.

BRIEF DESCRIPTION OF THE DRAWINGS

"The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which, like reference numerals identify like elements, and in which:

"FIG. 1 illustrates a user of the present invention and a light source;

"FIG. 2 illustrates a user of the present invention and a light source;

"FIG. 3 illustrates a circuit diagram of the present invention;

"FIG. 4 illustrates a display device with a front facing camera of the present invention;

"FIG. 5 illustrates a circuit diagram of the present invention;

"FIG. 6 illustrates a diagram of the operating system of the present invention;

"FIG. 7 illustrates a graph of ambient light versus screen brightness;

"FIG. 8 illustrates the measurement of ratio of the iris diameter to the pupil diameter D.sub.I/D.sub.P under low light conditions;

"FIG. 9 illustrates the measurement of ratio of the iris diameter to the pupil diameter D.sub.I/D.sub.P under bright light conditions;

"FIG. 10 illustrates a flowchart to turn on and turn off the screen of the display device of the present invention;

"FIG. 11 illustrates a flowchart to adjust the brightness level of the display device of the present invention;

"FIG. 12 illustrates a graph showing the relationship between the ratio of the iris diameter to the pupil diameter D.sub.I/D.sub.P and the desired brightness of the display device 100."

For more information, see this patent application: Bork, Stephan. Circuit to Adjust Backlighting for a Display Device. Filed October 14, 2012 and posted April 24, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4843&p=97&f=G&l=50&d=PG01&S1=20140417.PD.&OS=PD/20140417&RS=PD/20140417

Keywords for this news article include: Patents, Legal Issues.

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Source: Politics & Government Week


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