Response Time Compensation
Encyclopedia
Response time compensation is also known as "Overdrive". LCDs
moderate light flow by rotating liquid crystal
molecules to various alignments where they transmit more or less light depending on the electrical setting at each individual pixel
. The speed at which these liquid crystal molecules rotate is relatively slow, below the image refresh rate. As a consequence, when a scene is changing fast or there is a fast moving image being displayed (such as a golf ball
flying off the head of a club)the object is at best blurry and can disappear from the image entirely. Overdrive attempts to compensate for this by, instead of sending the desired voltage
to each pixel, it sends a higher initial voltage and then moderates that voltage in order to drive the rotation of the liquid crystal faster. Electrically it "steps on the gas" in order to get to the right speed quickly, then eases off as it approaches the desired performance level.
Overdrive was patent
ed by an individual inventor (Robert Hotto) whose company "Positive Technologies" owns the rights to it. The technology was copied by many of the large LCD companies and renamed to avoid paying royalties
. The ownership issues were eventually settled in a lawsuit
with the defendants agreeing to pay royalties to Positive Technologies.
Liquid crystal display
A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....
moderate light flow by rotating liquid crystal
Liquid crystal
Liquid crystals are a state of matter that have properties between those of a conventional liquid and those of a solid crystal. For instance, an LC may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of LC phases, which can be...
molecules to various alignments where they transmit more or less light depending on the electrical setting at each individual pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
. The speed at which these liquid crystal molecules rotate is relatively slow, below the image refresh rate. As a consequence, when a scene is changing fast or there is a fast moving image being displayed (such as a golf ball
Golf ball
A golf ball is a ball designed to be used in the game of golf.Under the Rules of Golf, a golf ball weighs no more than 1.620 oz , has a diameter not less than 1.680 in , and performs within specified velocity, distance, and symmetry limits...
flying off the head of a club)the object is at best blurry and can disappear from the image entirely. Overdrive attempts to compensate for this by, instead of sending the desired voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
to each pixel, it sends a higher initial voltage and then moderates that voltage in order to drive the rotation of the liquid crystal faster. Electrically it "steps on the gas" in order to get to the right speed quickly, then eases off as it approaches the desired performance level.
Overdrive was patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
ed by an individual inventor (Robert Hotto) whose company "Positive Technologies" owns the rights to it. The technology was copied by many of the large LCD companies and renamed to avoid paying royalties
Royalties
Royalties are usage-based payments made by one party to another for the right to ongoing use of an asset, sometimes an intellectual property...
. The ownership issues were eventually settled in a lawsuit
Lawsuit
A lawsuit or "suit in law" is a civil action brought in a court of law in which a plaintiff, a party who claims to have incurred loss as a result of a defendant's actions, demands a legal or equitable remedy. The defendant is required to respond to the plaintiff's complaint...
with the defendants agreeing to pay royalties to Positive Technologies.