US 7557788

Patent Summary: US 7,557,788 B1

Date of Analysis: April 26, 2026

A review of U.S. Patent 7,557,788 B1, titled "Gamma reference voltage generator," has been conducted based on information available from the U.S. Patent and Trademark Office (USPTO). A concurrent search of the 2026 dockets for the Court of Appeals for the Federal Circuit (CAFC) did not yield any results for this patent.

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Patent Overview

Title	Gamma reference voltage generator
Assignee	The assignment history for this patent is complex, with multiple reassignments. As of the latest available records, the assignee is noted as Phenix Longhorn LLC, with a security interest held by BR IP Ventures, LP. The original assignee was Alta Analog Inc.
Inventors	Richard V. Orlando, Trevor A. Blyth
Filing Date	May 1, 2007
Issue Date	July 7, 2009
Abstract	"A programmable buffer integrated circuit which can be programmed to output a set of gamma correction reference voltages to be used in LCD displays. Once programmed, the buffers will continuously output the programmed value. The device incorporates a programming interface to allow the programming of the buffer outputs to the desired values during manufacturing and test of the panel. Multiple sets of values can be programmed to provide different gamma correction curves for different user or application requirements."

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Plain-Language Summary of Independent Claims

This patent contains three independent claims (claims 1, 3, and 5). Below is a simplified explanation of the methods they describe.

Independent Claim 1: This claim outlines a method for calibrating an LCD screen to achieve a specific visual output, known as a "gamma curve." This is done to correct for small inconsistencies that occur from one display panel to another during manufacturing. The process involves:

• Using a display that has a built-in, electrically reprogrammable, and non-volatile (meaning it retains information without power) control for its gamma reference voltages.
• Testing the display's visual output using an external optical sensor.
• Adjusting the gamma voltage levels for the display's columns using an external control circuit.
• Using a separate computing device running a special algorithm to determine the optimal voltage levels based on the sensor's feedback.
• Saving these optimized voltage levels directly into the display's non-volatile gamma control system.

Independent Claim 3: This claim details a method for programming the gamma reference voltage generator chips that are attached to an LCD. The method is iterative and aims to fine-tune the display's visual output. The steps are:

• Selecting one or more columns on the LCD.
• Applying various gamma voltages to these columns.
• Storing these voltages in the reprogrammable, non-volatile cells within the gamma generator chips.
• Using a separate computing device with optimization algorithms to analyze the light coming from the selected columns.
• Modifying the applied gamma voltages based on the results from the optimization algorithms.
• Programming the new, modified voltages into the gamma generator's storage cells.
• Repeating this process of analyzing and modifying until the display's output meets the desired optimization criteria.

Independent Claim 5: This claim describes a comprehensive method for the entire lifecycle of using a liquid crystal display with this technology. It combines the calibration process with the display's normal operation:

• First, providing an LCD that has the electrically reprogrammable and non-volatile gamma control capability.
• Next, calibrating the display through a multi-step process: testing it with an external optical sensor, varying the gamma voltages, optimizing these voltages with an external algorithm based on sensor data, and storing the final voltage levels in the display's gamma control system.
• Then, during normal use, the display retrieves these stored gamma reference voltage levels from its memory.
• Finally, the display uses these retrieved voltage levels to show an image.

In essence, all independent claims describe methods to precisely and permanently tune the visual characteristics of an LCD panel during manufacturing by using external sensors and optimization algorithms, with the resulting settings being saved directly onto the display's hardware.