GAMMA CURVE COMPENSATING DEVICE AND METHOD USING THE SAME

Abstract

The present invention provides a gamma curve compensating device and method using the same. The gamma curve compensating device includes an amplifier module, a signal corrector, and an attenuating unit. The amplifier module receives and amplifies a signal, and couples to a first impedance element and a second impedance element. The signal corrector includes a third impedance element which serially connects to a first transistor and couples to the amplifier module. When the voltage difference between an output terminal of the amplifier module and a control terminal of the first transistor is larger than a startup voltage of the first transistor, the signal corrector changes the signal output by the amplifier module and generates a compensated video signal. The attenuating unit connects with the output terminal of the amplifier module to attenuate the signal at the output terminal of the amplifier module, thereby outputting the gamma compensated video signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a gamma curve voltage diagram of a conventional liquid crystal display (LCD).

FIG. 2 is a circuit diagram of a conventional grayscale display reference voltage generation circuit 21.

FIG. 3 is a circuit diagram of a conventional gamma correction and adjustment circuit 22.

FIG. 4 is a circuit diagram of a gamma curve compensating device according to one embodiment of the present invention.

FIG. 5A is a voltage-to-time diagram of an input video signal according to one embodiment of the present invention.

FIG. 5B is a voltage-to-time diagram of the video signal output by a signal output/input terminal B1 through the amplifier module 401 according to one embodiment of the present invention.

FIG. 5C is a voltage-to-time diagram of the video signal before compensated by the signal corrector 402 according to one embodiment of the present invention.

FIG. 5D is a voltage-to-time diagram of the video signal after compensated by the signal corrector 402 according to one embodiment of the present invention.

FIG. 5E is a voltage-to-time diagram of the compensated video signal output by the attenuating unit 403 and the follower impedance matching element 404 according to one embodiment of the present invention.

FIG. 6A is a voltage-to-time measuring diagram of the video signal before compensated by the gamma curve compensating device according to one embodiment of the present invention.

FIG. 6B is a voltage-to-time measuring diagram of the video signal after compensated by the gamma curve compensating device according to one embodiment of the present invention.

FIG. 7 is a flow chart of a gamma curve compensating method according to one embodiment of the present invention.

Claims

1. A gamma curve compensating device, comprising: a first impedance element;a second impedance element;an amplifier module with a first end coupled to the first impedance element and a second end coupled to the second impedance element, wherein the amplifier module receives a video signal and amplifies the video signal to provide an amplified signal via the second end;a signal corrector with a third impedance element and a first transistor, wherein a first end of the third impedance element is coupled to the second end of the amplifier module; a second end of the third impedance element is connected with the first transistor in series;and when the voltage difference between the voltage of the second end of the amplifier module and that of the control terminal of the first transistor is larger than a startup voltage of the first transistor, the signal corrector is used to receive the amplified signal to change the signal at the second end to generate a compensated video signal; andan attenuating unit connected with the second end for receiving the signal at the second end and attenuating the signal at the second end to output a gamma compensated video signal.

2. The gamma curve compensating device as claimed in claim 1, wherein the amplifier module comprises: a transistor with a control terminal and two signal input/output terminals, wherein the control terminal is used to receive the video signal.

3. The gamma curve compensating device as claimed in claim 2, wherein one end of the second impedance element is electrically coupled to a predetermined voltage, and the other end is electrically coupled to one signal input/output terminal of the transistor to output the amplified signal.

4. The gamma curve compensating device as claimed in claim 3, wherein one end of the first impedance element is electrically coupled to a ground voltage, and the other end is electrically coupled to the other signal input/output terminal of the transistor.

5. The gamma curve compensating device as claimed in claim 1, wherein each of the first and second impedance elements respectively comprises a resistor.

6. The gamma curve compensating device as claimed in claim 1, wherein the attenuating unit comprises: a transistor with a control terminal and two signal input/output terminals, wherein the control terminal is used to receive the compensated video signal;a fourth impedance element with one end electrically coupled to a predetermined voltage and the other end electrically coupled to one signal input/output terminal of the transistor; anda fifth impedance element with one end electrically coupled to a ground voltage and the other end electrically coupled to the other signal input/output terminal of the transistor to output the gamma compensated video signal.

7. The gamma curve compensating device as claimed in claim 6, wherein each of the fourth and fifth impedance elements comprises a resistor.

8. The gamma curve compensating device as claimed in claim 1 further comprising a follower impedance matching element, wherein one end of the follower impedance matching element receives the gamma compensated video signal and the other end is electrically coupled to a predetermined voltage.

9. A gamma curve compensating method, comprising: configuring a first impedance element to be electrically coupled to a second impedance element through an amplifier module;configuring a signal corrector with a third impedance element and a first transistor, wherein one end of the third impedance element is coupled to the amplifier module and the second impedance element;enabling the amplifier module to receive a video signal and to amplify the video signal, thereby generating an amplified signal;enabling the signal corrector to receive the amplified signal; andwhen the voltage difference between the voltage of the amplified signal and that of the control terminal of the first transistor is larger than a startup voltage of the first transistor, enabling the signal corrector to receive the amplified signal and to correct the amplified signal so as to generate a compensated video signal according to an impedance ratio obtained by comparing the impedance of the third impedance element and the second impedance element connected in parallel with that of the first impedance element.

10. The gamma curve compensating method as claimed in claim 9 further comprising: configuring an attenuating unit to be coupled to the coupling point between the third impedance element and the amplifier module, wherein the attenuating unit attenuates the signal at the coupling point between the third impedance element and the amplifier module, thereby outputting a gamma compensated video signal.