US 5,847,511 AGranted

Automatic image rotation compensation circuit and method

AssigneeSamsung Electronics Co., Ltd.

InventorJoo-Hyoung Lee

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Abstract

An automatic image rotation compensation circuit includes: a terrestrial magnetic field detecting unit for detecting horizontal and vertical terrestrial magnetic fields of a place where a display device is installed; an amplifying unit for amplifying the horizontal and vertical terrestrial magnetic field values detected by the terrestrial magnetic field detecting unit; an analog-to-digital converting unit for converting the analog terrestrial magnetic field values amplified by the amplifying unit into digital signals; a memory for storing image compensation reference values corresponding to various terrestrial magnetic field values; a microcomputer for receiving the digital terrestrial magnetic field values from the analog-to-digital converting unit and reading compensation values corresponding to the terrestrial magnetic field values; a digital-to-analog converting unit for converting the digital signals from the microcomputer into analog signals; and a deflection controller for performing a differential amplification on the signals transmitted from the digital-to-analog converting unit and changing a current flowing through rotation coils to control a tilt.

Claims11

Dependent claims

An automatic image rotation compensation circuit, comprising:

a terrestrial magnetic field detector for generating horizontal and vertical terrestrial magnetic field values by detecting horizontal and vertical terrestrial magnetic fields of a location where a display device is installed;
an amplifier for producing amplified field values by amplifying said horizontal and vertical terrestrial magnetic field values;
an analog-to-digital converter for converting the amplified field values into digital signals;
a memory for storing a plurality of magnetic field values and a plurality of terrestrial magnetic field reference values corresponding to said plurality magnetic field values;
a microcomputer for comparing said digital values to said plurality of magnetic field values and, based on a comparison result, selecting for output as a terrestrial magnetic field compensation value one of said terrestrial magnetic field reference values;
a digital-to-analog converting unit for converting said terrestrial magnetic field compensation value from said microcomputer into an analog signal;
a deflection controller for generating a control voltage by differentially amplifying said analog signal;
and
a rotation coil wrapped around a portion of said display device responsive to said control voltage for generating a compensating current to cancel said horizontal and vertical terrestrial magnetic fields, wherein said deflection controller comprises:
first and second resistors connected in series between a voltage source and a ground terminal;
a first operational amplifier having one input terminal connected to receive said analog signal via a third resistor;
a fourth resistor commonly connected to said first and second resistors for providing a reference voltage to another input terminal of said first operational amplifier;
a fifth resistor connected between said one input terminal and an output terminal of said first operational amplifier;
a second operational amplifier having a first input terminal connected to said output terminal of said first operational amplifier, an output terminal connected to a first end of said rotation coil, and a second input terminal connected to a second end of said rotation coil via a sixth resistor;
and
a seventh resistor connected between said second end of said rotation coil and said ground terminal.

13 more elements

An automatic image rotation compensation method for a display device, said method comprising the steps of:

generating a detected terrestrial magnetic field value by detecting a terrestrial magnetic field corresponding to a present location of said display device;
generating a terrestrial magnetic field compensation value by comparing said detected terrestrial magnetic field value to a plurality of stored values;
amplifying said terrestrial magnetic field value compensation value to produce a compensation voltage;
and
applying said compensation voltage to rotation coils wrapped around a portion of said display device to generate a compensating current to cancel said terrestrial magnetic field;
said step of generating a detected terrestrial magnetic field value comprises:
generating horizontal and vertical terrestrial magnetic field values by detecting horizontal and vertical terrestrial magnetic fields corresponding to said present location;
producing amplified field values by amplifying said horizontal and vertical terrestrial magnetic field values;
converting the amplified field values into digital signals;
and
combining said digital signals to produce said detected terrestrial magnetic field value;
and
said step of generating a terrestrial magnetic field compensation value comprises:
storing said detected terrestrial magnetic field value as a first variable;
comparing said first variable to a plurality of values stored in a memory;
reading out from said memory a terrestrial magnetic field reference value based on a result of said comparing step;
storing said terrestrial magnetic field reference value as a second variable;
and
outputting said second variable as said terrestrial magnetic field compensation value.

16 more elements

Dependencies are inferred from the claim text.