TWI793797B - Source driver of reducing interpolation error of channel operational amplifier circuit - Google Patents

Abstract

A source driver including a gamma circuit, a timing controller and a channel operational amplifier circuit is disclosed. The gamma circuit and the timing controller are coupled to the channel operational amplifier circuit. The timing controller provides display data to the channel operational amplifier circuit. The display data includes odd-numbered frames and plural-numbered frames. When the display data is an odd frame, the gamma circuit provides the first and second reference voltages to the channel operational amplifier circuit for the channel operational amplifier circuit to output the first interpolated voltage curve accordingly. When the display data is an even-numbered frame, the gamma circuit provides the first and second average voltages for the channel operational amplifier circuit to output the second interpolated voltage curve accordingly. The gamma circuit subtracts/adds the first and second reference voltages and then averages them to obtain the first/second average voltages respectively.

Description

Source Drivers to Reduce Interpolation Errors in Channel Operational Amplifier Circuits

The present invention relates to operational amplifiers, in particular to a source driver including a channel operational amplifier (CHOP) circuit capable of effectively eliminating the interpolation error of its output voltage curve.

Generally speaking, the traditional current controlled interpolation channel operational amplifier circuit applied to the source driver has an interpolation error caused by poor tail current (Tail current) accuracy during actual operation.

Please refer to FIG. 1 . FIG. 1 is a schematic diagram showing the interpolation error between the traditional actual voltage curve and the ideal voltage curve. As shown in Figure 1, assuming that the interpolation area IPA is located between the first reference voltage VA and the second reference voltage VB, then between the first reference voltage VA and the average voltage (VA+VB)/2, due to the actual voltage The curve CU has an interpolation error ER which is larger than the ideal voltage curve ID; between the average voltage (VA+VB)/2 and the second reference voltage VB, since the actual voltage curve CU has an interpolation error ER which is smaller than the ideal voltage curve ID, As a result, deviations may occur in the display images of the display panel, and further improvement is urgently needed.

Therefore, the present invention proposes a source driver including a channel operational amplifier circuit capable of effectively eliminating the interpolation error of its output voltage curve, so as to solve the problems encountered in the prior art.

A preferred embodiment of the present invention is a source driver. In this embodiment, the source driver includes a channel operational amplifier circuit, a timing controller and a gamma circuit. The timing controller is coupled to the channel operational amplifier circuit for providing display data to the channel operational amplifier circuit, wherein the display data includes odd frames and even frames. The gamma circuit is coupled to the channel operational amplifier circuit. When the display data is an odd frame, the gamma circuit provides the first reference voltage and the second reference voltage to the channel operational amplifier circuit for the channel operational amplifier circuit to output the first voltage curve; when the display data is an even frame, the gamma circuit The Ma circuit provides a first average voltage and a second average voltage channel operational amplifier circuit for the channel operational amplifier circuit to output a second voltage curve, wherein the Gamma circuit subtracts the first reference voltage from the second reference voltage respectively After adding / and averaging, the first average voltage and the second average voltage are obtained.

In one embodiment, if the first reference voltage is VA and the second reference voltage is VB, the gamma circuit subtracts the first reference voltage VA from the second reference voltage VB and averages them to obtain the first average voltage as ( VA-VB)/2, and the first average voltage (VA-VB)/2 is less than the first reference voltage VA.

In one embodiment, if the first reference voltage is VA and the second reference voltage is VB, then the gamma circuit adds the first reference voltage VA and the second reference voltage VB and averages them to obtain the second average voltage as ( VA+VB)/2, and the second average voltage (VA+VB)/2 is greater than the first reference voltage VA and less than the second reference voltage VB.

In one embodiment, the first voltage curve corresponds to the first interpolation area and the first interpolation area is located between the first reference voltage and the second reference voltage, and the second voltage curve is Affected by the displacement signal, it corresponds to the second interpolation area and the second interpolation area is located between the first average voltage and the second average voltage.

In one embodiment, the first interpolation area and the second interpolation area overlap each other between the first reference voltage and the second average voltage.

In one embodiment, between the first reference voltage and the second average voltage, the first voltage curve when the pixel displays odd frames and the second voltage curve when the pixel displays even frames are symmetrical to the ideal voltage curve.

In one embodiment, the first voltage curve has a first interpolation error larger than the ideal voltage curve and the second voltage curve has a second interpolation error smaller than the ideal voltage curve, the difference between the first interpolation error and the second interpolation error equal in size.

In one embodiment, an ideal voltage curve is obtained after the first voltage curve and the second voltage curve are averaged in the time domain.

In one embodiment, when the display data is an odd number of frames, the first code, the second code and the third code from small to large correspond to the first reference voltage, the second average voltage and the second reference voltage respectively.

In one embodiment, when the display data is an even frame, the first code, the second code and the third code from small to large correspond to the first average voltage, the first reference voltage and the second average voltage respectively.

Compared with the prior art, the present invention proposes a source driver including a channel operational amplifier circuit, and its gamma circuit provides different reference voltages to the channel operational amplifier circuit when the pixels of the display panel display odd frames and even frames, so that the channel The first voltage curve and the second voltage curve respectively output by the operational amplifier circuit when displaying odd frames and even frames can be averaged in the time domain in the interpolation area to effectively eliminate the interpolation of the first voltage curve and the second voltage curve error to get the ideal voltage curve.

ID: ideal voltage curve

CU: actual voltage curve

ER: Interpolation Error

IPA: Interpolation Area

2: Source driver

20: Gamma (Gamma) circuit

21: Timing controller

22: Channel operational amplifier circuit

F1: first frame

F2: second frame

F3: third frame

F4: the fourth frame

F5: fifth frame

F6: sixth frame

DATA: display data

SH: displacement signal

+: addition unit

VA: the first reference voltage

VB: Second reference voltage

(VA-VB)/2: first average voltage

(VA+VB)/2: Second average voltage

XX0000: encoding

XX1000: Coding

XX1111: Coding

CU1: first voltage curve

CU2: Second voltage curve

IPA1: first interpolation area

IPA2: the second interpolation area

ER1: First interpolation error

ER2: second interpolation error

FIG. 1 is a schematic diagram illustrating that a conventional actual voltage curve has an interpolation error and deviates from an ideal voltage curve.

2A and FIG. 2B respectively illustrate schematic diagrams of a source driver including a channel operational amplifier circuit operating when the display data is an odd frame and an even frame in a specific embodiment of the present invention.

FIG. 3 shows a schematic diagram of the present invention approaching an ideal voltage curve by averaging different actual voltage curves when displaying odd frames and even frames in the time domain to effectively eliminate interpolation errors.

A preferred embodiment of the present invention is a source driver including a channel operational amplifier circuit. In this embodiment, the source driver including the channel operational amplifier circuit can be applied to the display device and the channel operational amplifier circuit can be coupled to the display panel through the data line, but not limited thereto.

Please refer to FIG. 2A and FIG. 2B . FIG. 2A and FIG. 2B respectively illustrate schematic diagrams of the operation of the source driver 2 including the channel operational amplifier circuit 22 in this embodiment when the display data is an odd frame and an even frame.

As shown in FIG. 2A , the source driver 2 includes a gamma circuit 20 , a timing controller 21 and a channel operational amplifier circuit 22 . The timing controller 21 is coupled to the channel operational amplifier circuit 22 for providing display data DATA to the channel operational amplifier circuit 22 , wherein the display data DATA includes odd frames and even frames. The gamma circuit 20 is coupled to the channel operational amplifier circuit 22 .

When the display data DATA provided by the timing controller 21 is an odd frame (such as During the first frame F1, the third frame F3, the fifth frame F5...), the gamma circuit 20 provides the first reference voltage VA and the second reference voltage VB to the channel operational amplifier circuit 22 for the channel operational amplifier circuit 22 according to the first frame A reference voltage VA and a second reference voltage VB output the first voltage, and the curve corresponding to the first voltage is the first voltage curve CU1 shown in FIG. 3 .

As shown in FIG. 2B, when the display data DATA provided by the timing controller 21 is an even frame (such as the second frame F2, the fourth frame F4, the sixth frame F6...), it is set between the timing controller 21 and the channel operational amplifier. The addition unit + between the circuits 22 adds the shift signal SH to the even frames of the display data DATA (such as the second frame F2 , the fourth frame F4 , the sixth frame F6 . . . ) and provides it to the channel operational amplifier circuit 22 .

At this time, the gamma circuit 20 no longer provides the first reference voltage VA and the second reference voltage VB to the channel operational amplifier circuit 22, but instead provides the first average voltage (VA-VB)/2 and the second average voltage ( VA+VB)/2 to the channel operational amplifier circuit 22, for the channel operational amplifier circuit 22 to output the second voltage according to the first average voltage (VA-VB)/2 and the second average voltage (VA+VB)/2 and the second The curve of the two voltages corresponding to the code is the second voltage curve CU2 shown in FIG. 3 .

It should be noted that, the gamma circuit 20 respectively subtracts/adds the first reference voltage VA and the second reference voltage VB and averages them to obtain the first average voltage (VA−VB)/2 and the second average voltage ( VA+VB)/2, but not limited thereto.

Next, please refer to FIG. 3 . FIG. 3 shows a schematic diagram of the present invention approaching an ideal voltage curve by averaging different actual voltage curves when displaying odd frames and even frames in the time domain to effectively eliminate interpolation errors.

As shown in FIG. 3, when the display data DATA is an odd frame (such as the first frame F1, the third frame F3, the fifth frame F5...), the first voltage output by the channel operational amplifier circuit 22 is The first voltage curve CU1 corresponding to encoding corresponds to the first interpolation area IPA1 and the first interpolation area IPA1 is located between the first reference voltage VA and the second reference voltage VB.

Since the first voltage curve CU1 is greater than the ideal voltage curve ID between the first reference voltage VA and the second average voltage (VA+VB)/2, and the first voltage curve CU1 is between the second average voltage (VA+VB)/2 The distance between the second reference voltage VB and the ideal voltage curve ID is smaller than the ideal voltage curve ID. Therefore, there will be three intersection points between the first voltage curve CU1 and the ideal voltage curve ID: the first intersection point corresponds to the first reference voltage VA and the first code XX0000, and the first intersection point corresponds to the first code XX0000. The two intersections correspond to the second average voltage (VA+VB)/2 and the second code XX1000, and the third intersection corresponds to the second reference voltage VB and the third code XX1111.

When the display data DATA is an even-numbered frame (such as the second frame F2, the fourth frame F4, the sixth frame F6...), the second voltage output by the channel operational amplifier circuit 22 corresponds to the code because the shift signal SH is added to it. The second voltage curve CU2 is shifted to correspond to a second interpolation area IPA2 different from the first interpolation area IPA1. The second interpolation area IPA2 is located between the first average voltage (VA-VB)/2 and the second average voltage (VA+VB)/2.

Since the second voltage curve CU2 is greater than the ideal voltage curve ID between the first average voltage (VA-VB)/2 and the first reference voltage VA and the second voltage curve CU2 is between the first reference voltage VA and the second average voltage ( VA+VB)/2 is smaller than the ideal voltage curve ID, therefore, the second voltage curve CU2 and the ideal voltage curve ID will have three intersections: the first intersection corresponds to the first average voltage (VA-VB)/2 and The first code XX0000, the second intersection point correspond to the first reference voltage VA and the second code XX1000, and the third intersection point corresponds to the second average voltage (VA+VB)/2 and the third code XX1111.

The first interpolation area IPA1 corresponding to the first voltage curve CU1 at the odd frame and the second interpolation area IPA2 corresponding to the second voltage curve CU2 at the even frame overlap each other between the first reference voltage VA and the first reference voltage VA. Between two average voltages (VA+VB)/2. at first Between the reference voltage VA and the second average voltage (VA+VB)/2, the first voltage curve CU1 at odd frames and the second voltage curve CU2 at even frames are symmetrical to the ideal voltage curve ID. The first voltage curve CU1 has a first interpolation error ER1 which is larger than the ideal voltage curve ID and the second voltage curve CU2 has a second interpolation error ER2 which is smaller than the ideal voltage curve ID. The first interpolation error ER1 and the second interpolation error ER2 is equal in size. Therefore, when the pixels of the display panel sequentially display odd frames (such as the first frame F1) and even frames (such as the second frame F2), the first reference voltage VA and the second average voltage (VA+VB)/2 Between the first voltage curve CU1 of the odd frame (such as the first frame F1) and the second voltage curve CU2 of the even frame (such as the second frame F2) are averaged in the time domain, so that the first voltage curve CU1 of the first voltage curve CU1 An interpolation error ER1 and a second interpolation error ER2 of the second voltage curve CU2 cancel each other to obtain an ideal voltage curve ID.

Compared with the prior art, the present invention proposes a source driver including a channel operational amplifier circuit, and its gamma circuit provides different reference voltages to the channel operational amplifier circuit when the pixels of the display panel display odd frames and even frames, so that the channel The first voltage curve and the second voltage curve respectively output by the operational amplifier circuit when displaying odd frames and even frames can be averaged in the time domain in the interpolation area to effectively eliminate the interpolation of the first voltage curve and the second voltage curve error to get the ideal voltage curve.

2: Source driver

20: Gamma (Gamma) circuit

21: Timing controller

22: Channel operational amplifier circuit

F2: second frame

F4: the fourth frame

F6: sixth frame

DATA: display data

SH: displacement signal

+: addition unit

VA: the first reference voltage

VB: Second reference voltage

(VA-VB)/2: first average voltage

(VA+VB)/2: Second average voltage

Claims (10)

A source driver, comprising: a channel operational amplifier circuit; a timing controller coupled to the channel operational amplifier circuit to provide display data to the channel operational amplifier circuit, wherein the display data includes odd frames and even frames; and gamma A circuit, coupled to the channel operational amplifier circuit, when the display data is the odd frame, the gamma circuit provides the first reference voltage and the second reference voltage to the channel operational amplifier circuit for the channel operational amplifier circuit to use Output the first voltage curve; when the display data is the even frame, the gamma circuit provides the first average voltage and the second average voltage to the channel operational amplifier circuit, so that the channel operational amplifier circuit can output the second voltage accordingly curve, wherein the gamma circuit obtains the first average voltage and the second average voltage by subtracting/adding the first reference voltage and the second reference voltage respectively and then averaging. The source driver as claimed in claim 1, wherein if the first reference voltage is VA and the second reference voltage is VB, the gamma circuit subtracts the first reference voltage VA from the second reference voltage VB The first average voltage is then averaged to obtain (VA-VB)/2, and the first average voltage (VA-VB)/2 is smaller than the first reference voltage VA. The source driver as claimed in claim 1, wherein if the first reference voltage is VA and the second reference voltage is VB, the gamma circuit adds the first reference voltage VA and the second reference voltage VB After averaging, the second average voltage is (VA+VB)/2, and the second average voltage (VA+VB)/2 is greater than the first reference voltage VA and less than the second reference voltage VB. The source driver as claimed in claim 1, wherein the first voltage curve corresponds to a first interpolation region and the first interpolation region is located between the first reference voltage and the second reference voltage, the second voltage The curve is influenced by the displacement signal and corresponds to a second interpolation area, and the second interpolation area is located between the first average voltage and the second average voltage. The source driver as claimed in claim 4, wherein the first interpolation area and the second interpolation area overlap each other between the first reference voltage and the second average voltage. The source driver as described in claim 5, wherein between the first reference voltage and the second average voltage, the first voltage curve when the pixel displays the odd frame and the pixel display the even frame The second voltage curves are mutually symmetrical to the ideal voltage curves. The source driver as claimed in claim 6, wherein the first voltage curve has a first interpolation error larger than the ideal voltage curve and the second voltage curve has a second interpolation error smaller than the ideal voltage curve, the first An interpolation error is equal in magnitude to the second interpolation error. The source driver as claimed in claim 6, wherein the ideal voltage curve is obtained after time-domain averaging of the first voltage curve and the second voltage curve. The source driver according to claim 1, wherein when the display data is the odd frame, the first code, the second code, and the third code from small to large correspond to the first reference voltage, the second average voltage and the second reference voltage. The source driver as described in claim 1, wherein when the display data is the even frame, the first code, the second code and the third code from small to large are respectively corresponding to the first average voltage, the first reference voltage and the second average voltage.

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