CN108682403B - Gamma voltage switching device and liquid crystal display device - Google Patents
Gamma voltage switching device and liquid crystal display device Download PDFInfo
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3648—Control of matrices with row and column drivers using an active matrix
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3696—Generation of voltages supplied to electrode drivers
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0235—Field-sequential colour display
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0242—Compensation of deficiencies in the appearance of colours
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0271—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
- G09G2320/0276—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0285—Improving the quality of display appearance using tables for spatial correction of display data
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/06—Adjustment of display parameters
- G09G2320/0673—Adjustment of display parameters for control of gamma adjustment, e.g. selecting another gamma curve
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/06—Adjustment of display parameters
- G09G2320/0693—Calibration of display systems
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- Engineering & Computer Science (AREA)
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- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
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- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Liquid Crystal Display Device Control (AREA)
Abstract
The invention provides a gamma voltage switching device, which comprises a switching control circuit and a voltage output circuit, wherein the switching control circuit is used for outputting a switching signal according to a received first switching control signal and a received second switching control signal; the voltage output circuit comprises a first resistor string, a plurality of first switch elements, a second switch element and a gamma voltage chip, wherein the gamma voltage chip respectively outputs a second group of gamma voltages or a third group of gamma voltages according to the level of a first switching control signal, when the switching signal is at an effective level, the gamma voltage chip stops outputting the second group of gamma voltages or the third group of gamma voltages, and each first switch element is conducted, so that the first resistor string outputs the first group of gamma voltages to the source electrode driving circuit. The invention also provides a liquid crystal display device. The gamma voltage switching device and the liquid crystal display device can provide three groups of gamma voltages to the source electrode driving circuit and switch the three groups of gamma voltages in real time, thereby improving gray scale inversion.
Description
Technical Field
The present invention relates to the field of liquid crystal display, and more particularly, to a gamma voltage switching device and a liquid crystal display device.
Background
Liquid Crystal Display devices (L liquid Crystal Display, L CD) have the advantages of good picture quality, small size, light weight, low driving voltage, low power consumption, no radiation, relatively low manufacturing cost, and the like, and currently dominate the flat panel Display field.
At present, the demand for the picture quality of the liquid crystal display device is increasing. However, the source driving circuit of the prior art liquid crystal display device can only switch two sets of gamma voltages, and the gray scale inversion occurs in the image.
Disclosure of Invention
In view of the above, the present invention is directed to a gamma voltage switching device, which can solve the problem of gray scale inversion of a display screen caused by only providing two sets of gamma voltages.
Specifically, the invention provides a gamma voltage switching device, which comprises a switching control circuit and a voltage output circuit, wherein the switching control circuit is used for outputting a switching signal according to a received first switching control signal and a received second switching control signal. The voltage output circuit includes a first resistor string, a plurality of first switching elements, a second switching element, and a gamma voltage chip. The first resistor string is used for generating a first group of gamma voltages and comprises a plurality of first resistors, a first end of the first resistor string receives a first power supply voltage, and a second end of the first resistor string is grounded. Each first switch element comprises a first control end, a first path end and a second path end, the first control end of each first switch element receives the switching signal, the first path end of each first switch element is respectively connected with the common end of every two adjacent first resistors in the first resistor string, and the second path end of each first switch element is connected with the source electrode driving circuit. The second switch element comprises a second control end, a third path end and a fourth path end, the second control end of the second switch element receives the switching signal, and the third path end of the second switch element receives the first power voltage. The gamma voltage chip comprises an enabling end and a plurality of voltage output ends, the enabling end of the gamma voltage chip is connected with the fourth path end of the second switch element, and the output ends of the plurality of voltage output ends of the gamma voltage chip are respectively connected with the second path end of each first switch element in a one-to-one correspondence mode. When the switching signal is at an inactive level, the gamma voltage chip outputs a second set of gamma voltages or a third set of gamma voltages according to the level of the first switching control signal, and when the switching signal is at an active level, the gamma voltage chip stops outputting the second set of gamma voltages or the third set of gamma voltages, and each first switch element is turned on, so that the first resistor string outputs the first set of gamma voltages to the source driving circuit through the plurality of first switch elements.
Preferably, the active level of the switching signal is a high level.
Preferably, each of the first switching elements is a TFT transistor and is integrated on the source driving board.
Preferably, the second switching control signal is an alternating current signal which is alternately high and low in switching every frame.
Preferably, the switching control circuit includes a third switching element, a fourth switching element, a second resistor, and a third resistor. The third switching element includes a third control terminal, a fifth path terminal, and a sixth path terminal, the third control terminal of the third switching element receives the first switching control signal, and the sixth path terminal of the third switching element is grounded. The fourth switching element comprises a fourth control end, a seventh path end and an eighth path end, the fourth control end of the fourth switching element is connected with the fifth path end of the third switching element, the seventh path end of the fourth switching element receives the second switching control signal, and the eighth path end of the fourth switching element outputs the switching signal. A first end of the second resistor is connected to a seventh path end of the fourth switching element, and a second end of the second resistor is connected to a fifth path end of the third switching element. A first end of the third resistor is connected to the eighth path end of the fourth switching element, and a second end of the third resistor is grounded.
Preferably, each first switching element is an N-type TFT transistor, the second switching element and the fourth switching element are PMOS transistors, and the third switching element is an NMOS transistor.
Preferably, the switching control circuit includes a fifth switching element, a sixth switching element, a seventh switching element, a fourth resistor, and a fifth resistor. The fifth switch element comprises a fifth control end, a ninth path end and a tenth path end, the fifth control end of the fifth switch element receives the first switching control signal, and the tenth path end of the fifth switch element is grounded. The sixth switching element includes a sixth control end, an eleventh path end, and a tenth path end, the sixth control end of the sixth switching element receives the second switching control signal, and the tenth path end of the sixth switching element is connected to the ninth path end of the fifth switching element. The seventh switching element comprises a seventh control end, a tenth path end and a tenth path end, the seventh control end of the seventh switching element is connected with the eleventh path end of the sixth switching element, the thirteenth path end of the seventh switching element outputs the switching signal, and the tenth path end of the seventh switching element is grounded. A first end of the fourth resistor receives a second power supply voltage, and a second end of the fourth resistor is connected to the eleventh path terminal of the sixth switching element. A fifth resistor, a first end of which receives the second power supply voltage, and a second end of which is connected to a tenth path end of the seventh switching element.
Preferably, each of the first switching elements is an N-type TFT transistor, the second switching element is a PMOS transistor, and the fifth switching element, the sixth switching element and the seventh switching element are NMOS transistors.
The invention also provides a liquid crystal display device which comprises the gamma voltage switching device.
The gamma voltage switching device and the liquid crystal display device can provide three groups of gamma voltages to the source electrode driving circuit and can switch the three groups of gamma voltages in real time, thereby improving the phenomenon of gray scale inversion. In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a circuit diagram of a gamma voltage switching device according to a first embodiment.
FIG. 2 is a circuit diagram of a gamma voltage switching device according to a second embodiment.
Detailed Description
To further illustrate the technical means and effects of the present invention for achieving the intended purpose, the following detailed description is given to specific embodiments, methods, steps, structures, features and effects of the gamma voltage switching device and the liquid crystal display device according to the present invention with reference to the accompanying drawings and preferred embodiments.
The foregoing and other aspects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings. While the invention has been described in connection with specific embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.
First embodiment
Referring to fig. 1, fig. 1 is a circuit connection diagram of a gamma voltage switching device according to a first embodiment. As shown in fig. 1, the gamma voltage switching device of the present embodiment includes a switching control circuit 100 and a voltage output circuit 200. The switching control circuit 100 of the present embodiment is configured to output a switching signal according to the received first switching control signal S1 and second switching control signal S2. The switching control circuit 100 of the present embodiment includes a third switching element T3, a fourth switching element T4, a second resistor R2, and a third resistor R3. The third switching element T3 includes a third control terminal, a fifth path terminal and a sixth path terminal, the third control terminal of the third switching element T3 receives the first switching control signal S1, and the sixth path terminal of the third switching element T3 is grounded. The fourth switching element T4 includes a fourth control terminal, a seventh path terminal and an eighth path terminal, the fourth control terminal of the fourth switching element T4 is connected to the fifth path terminal of the third switching element T3, the seventh path terminal of the fourth switching element T4 receives the second switching control signal S2, and the eighth path terminal of the fourth switching element T4 outputs the switching signal. A first terminal of the second resistor R2 is connected to the seventh path terminal of the fourth switching element T4, and a second terminal of the second resistor R2 is connected to the fifth path terminal of the third switching element T3. A first terminal of the third resistor R3 is connected to the eighth path terminal of the fourth switching element T4, and a second terminal of the third resistor R3 is grounded.
In this embodiment, the third switching element T3 is an NMOS transistor, and certainly, the third switching element T3 may also be an NPN transistor, etc.; the fourth switching element T4 of the present embodiment is a PMOS transistor, and of course, the fourth switching element T4 may also be a PNP transistor, etc.
The voltage output circuit 200 of the present embodiment includes a first resistor string 210, a plurality of first switching elements T1, a second switching element T2, and a Gamma voltage chip 220(P-Gamma IC).
The first resistor string 210 is configured to generate a first set of Gamma voltages Gamma1, the first resistor string 210 includes a plurality of first resistors R1 (15 resistors are shown in the figure), a first terminal of the first resistor string 210 receives a first power voltage AVDD1, and a second terminal of the first resistor string 210 is grounded. The first power voltage AVDD1 provides a reference voltage for the first resistor string 210, so that the first resistor string 210 divides the voltage by the first resistors R1 to obtain a corresponding Gamma voltage, and further generates a first set of Gamma voltages Gamma 1. It can be understood by those skilled in the art that the number of the first resistors R1 included in the first resistor string 210 can be set as required to set the number of the Gamma voltages of the first group Gamma1, and the voltage value of each Gamma voltage of the first group Gamma1 can be set by setting the resistance value of the first resistor R1. Each of the first switch elements T1, T1 includes a first control end, a first pass end and a second pass end, the first control end of each of the first switch elements T1 receives a switching signal, the first pass end of each of the first switch elements T1 is respectively connected to a common end of every two adjacent first resistors R1 in the first resistor string 210, and the second pass end of each of the first switch elements T1 is connected to a source driver circuit (not shown in the figure).
In one embodiment, the first switching elements T1 may be TFT transistors, and are integrated on the source driving board. The first switching element T1 of this embodiment may be an N-type TFT, but this embodiment is not limited thereto, and may also be an NMOS transistor, an NPN transistor, or the like. In other embodiments, the first switching element T1 may also be a P-type TFT transistor, a PMOS transistor, a PNP transistor, or the like.
Wherein the second switching element T2 includes a second control terminal, a third path terminal and a fourth path terminal. The second control terminal of the second switching element T2 receives the switching signal, the third path terminal of the second switching element T2 receives the first power voltage AVDD1, and the fourth path terminal of the second switching element T2 is connected to the enable terminal of the gamma voltage chip 220. The second switch element T2 of the present embodiment may be a PMOS transistor, which can achieve the effect of fast switching voltage and avoid the display effect being affected at the moment of switching; and it is possible to prevent voltage back-flowing between the first resistor string 210 outputting the first group Gamma voltage Gamma1 and the Gamma voltage chip 220 outputting the second group Gamma voltage Gamma 2. However, the embodiment is not limited thereto, and the second switching element T2 may also be a PNP transistor or the like. In other embodiments, the second switching element T2 may also be an NMOS transistor, an NPN transistor, or the like.
The gamma voltage chip 220 includes an enable terminal and a plurality of voltage output terminals. The enable terminal of the gamma voltage chip 220 is connected to the fourth pass terminal of the second switching element T2, and a plurality of voltage output terminals of the gamma voltage chip 220 are respectively connected to the second pass terminals of each of the first switching elements T1 in a one-to-one correspondence. When the switching signal is at the inactive level, the Gamma voltage chip 220 outputs the second Gamma voltage Gamma2 or the third Gamma voltage Gamma3 according to the level of the first switching control signal S1, and when the switching signal is at the active level, the Gamma voltage chip 220 stops outputting the second Gamma voltage Gamma2 or the third Gamma voltage Gamma3, and each of the first switch elements T1 is turned on, so that the first resistor string 210 outputs the first Gamma voltage Gamma1 to the source driving circuit through the first switch elements.
Specifically, when the first switching control signal S1 is at a low level, the first control terminal of the third switching element T3 receives the first switching control signal S1 at a low level, the third switching element T3 is turned off, so that the fifth switch terminal of the third switching element T3 may not be grounded through the turned-off third switching element T3, at this time, the fourth control terminal of the fourth switching element T4 may receive the second switching control signal S2 through the second resistor R2, and the seventh switch terminal of the fourth switching element T4 receives the second switching control signal S2, so that the fourth switching element T4 is turned off, so that the eighth switch terminal of the fourth switching element T4 may be at a low level, when the voltage at the fourth control terminal of the fourth switching element T4 is equal to the voltage at the seventh switch terminal of the fourth switching element T4, and the negative voltage at the eighth switch terminal of the fourth switching element T4 is at a low level, that is, the switching signal output from the eighth path terminal of the fourth switching element T4 is at the low level.
When the first switching control signal S1 is at a high level, the first control terminal of the third switching element T3 receiving the first switching control signal S1 is at a high level, the third switching element T3 is turned on, so that the fifth terminal of the third switching element T3 is grounded at a low level through the turned-on third switching element T3, and at this time, the fourth control terminal of the fourth switching element T4 is connected to the fifth terminal of the third switching element T3 at a low level. When the second switching control signal S2 is at a low level, the seventh path terminal of the fourth switching element T4 receives the second switching control signal S2 as a low level, and then the voltages at the fourth control terminal of the fourth switching element T4 and the seventh path terminal of the fourth switching element T4 do not reach the negative voltage turn-on condition of the fourth switching element T4, then the fourth switching element T4 is turned off, so that the eighth path terminal of the fourth switching element T4 is grounded as a low level through the third resistor R3, that is, the switching signal output by the eighth path terminal of the fourth switching element T4 is at a low level. When the second switching control signal S2 is at a high level, the seventh path terminal of the fourth switching element T4 receives the second switching control signal S2 as a high level, the voltages at the fourth control terminal of the fourth switching element T4 and the seventh path terminal of the fourth switching element T4 can reach the negative voltage turn-on condition of the fourth switching element T4, and the fourth switching element T4 is turned on, so that the eighth path terminal of the fourth switching element T4 receives the second switching control signal S2 as a high level through the turned-on fourth switching element T4, that is, the switching signal output by the eighth path terminal of the fourth switching element T4 is at a high level.
Therefore, the switching signal is at a high level only when both the first switching control signal S1 and the second switching control signal S2 are at a high level, and the switching signal is at a low level when either one of the first switching control signal S1 and the second switching control signal S2 is at a low level. While the active level of the switching signal of the present embodiment is high level. In other embodiments, the active level of the switching signal may also be a low level for turning on the corresponding plurality of first switching elements T1 and turning off the second switching element T2.
The Gamma voltage chip 220 receives the first switching control signal S1, and outputs the second Gamma voltage Gamma2 or the third Gamma voltage Gamma3 according to the level of the first switching control signal S1 when the switching signal is at the inactive level, i.e. when the first switching control signal S1 is at the high level, the Gamma voltage chip 220 outputs the second Gamma voltage Gamma2, and when the first switching control signal S1 is at the low level, the Gamma voltage chip 220 outputs the third Gamma voltage Gamma 3. When the switching signal is at the active level, the Gamma voltage chip 220 stops outputting the second group of Gamma voltages Gamma2 or the third group of Gamma voltages Gamma3, specifically, the second control terminal of the second switch element T2 of the embodiment receives the active level to turn off the second switch element T2, the enable terminal of the Gamma voltage chip 220 may not receive the first power voltage AVDD1 through the turned-off second switch element T2, and the enable terminal of the Gamma voltage chip 220 is at the low level to stop outputting the second group of Gamma voltages Gamma2 or the third group of Gamma voltages Gamma3 by the Gamma voltage chip 220; in another embodiment, the second control terminal of the second switch element receives an active level to turn on the second switch element T2, and the enable terminal of the Gamma voltage chip 220 can receive the first power voltage AVDD1 through the turned-on second switch element T2, so that the enable terminal of the Gamma voltage chip 220 is at a high level, and the Gamma voltage chip 220 stops outputting the second Gamma voltage Gamma2 or the third Gamma voltage Gamma 3. Meanwhile, when each first switching element T1 receives the active level of the switching signal, each first switching element T1 is turned on, so that the voltage (V1, V2.. V13, V14) between every two adjacent first resistors R1 in the first resistor string 210 can be output to a source driving circuit (not shown in the figure) through the turned-on first switching elements T1, and the voltages V1 to V14 are the first group Gamma voltages Gamma1, that is, the first resistor string 210 outputs the first group Gamma voltages Gamma1 to the source driving circuit through the turned-on first switching elements T1.
Therefore, the gamma voltage switching device of the present embodiment can switch and output three sets of gamma voltages in real time according to the first switching control signal S1 and the second switching control signal S2 (refer to the following table specifically), so as to improve the phenomenon of gray level inversion. However, the present invention is not limited to the case where the first switching control signal S1 and the second switching control signal S2 are both at a high level, and the switching signal is at an active level, for example, in other embodiments, the switching signal may be at an active level when the first switching control signal S1 and the second switching control signal S2 are both at a low level, and accordingly, the Gamma voltage switching device outputs the second Gamma voltage Gamma2 when the first switching control signal S1 is at a low level; when the first switching control signal S1 is at a low level, the Gamma voltage switching device respectively outputs the third Gamma voltage Gamma3 or the first Gamma voltage Gamma1 according to the level of the second switching control signal S2.
The low level in this embodiment is not limited to a voltage close to 0V, but may be a positive voltage at a high level and a negative voltage at a relatively low level.
In one embodiment, the second switching control signal S2 is an ac signal that is alternately high and low when switched every frame, and may be a signal output from a shift register to a gate driving unit, for example. Therefore, when the first switching control signal S1 is at a low level, the Gamma voltage switching device outputs a third set of Gamma voltages Gamma 3; when the first switching control signal S1 is at a high level and the second switching control signal S2 is an ac signal that is alternately at a high level and a low level during each frame switching, the Gamma voltage switching device alternately outputs the first Gamma voltage Gamma1 and the second Gamma voltage Gamma2 during each frame switching, thereby better improving the phenomenon of gray scale inversion.
The gamma voltage switching device of the embodiment can provide three groups of gamma voltages to the source electrode driving circuit and can switch the three groups of gamma voltages in real time, thereby improving the phenomenon of gray scale inversion.
Second embodiment
FIG. 2 is a circuit diagram of a gamma voltage switching device according to a second embodiment. The second embodiment is substantially the same as the first embodiment except that the switching control circuit 100 includes a fifth switching element T5, a sixth switching element T6, a seventh switching element T7, a fourth resistor R4, and a fifth resistor R5. The fifth switching element T5 includes a fifth control terminal, a ninth path terminal and a tenth path terminal, the fifth control terminal of the fifth switching element T5 receives the first switching control signal S1, and the tenth path terminal of the fifth switching element T5 is grounded. The sixth switching element T6 includes a sixth control terminal, an eleventh path terminal, and a tenth path terminal, the sixth control terminal of the sixth switching element T6 receives the second switching control signal S2, and the tenth path terminal of the sixth switching element T6 is connected to the ninth path terminal of the fifth switching element T5. The seventh switching element T7 includes a seventh control terminal, a tenth path terminal and a tenth path terminal, the seventh control terminal of the seventh switching element T7 is connected to the eleventh path terminal of the sixth switching element T6, the thirteenth path terminal of the seventh switching element T7 outputs a switching signal, and the tenth path terminal of the seventh switching element T7 is grounded. A first terminal of the fourth resistor R4 receives the second power voltage AVDD2, and a second terminal of the fourth resistor R4 is connected to the eleventh path terminal of the sixth switching element T6. A first end of the fifth resistor R5 and a first end of the fifth resistor R5 receive the second power voltage AVDD2, and a second end of the fifth resistor R5 is connected to the tenth path end of the seventh switching element T7.
In this embodiment, the fifth switching element T5, the sixth switching element T6, and the seventh switching element T7 may all be NMOS transistors, but the embodiment is not limited thereto, and may also be NPN triodes and the like.
The second power voltage AVDD2 is used to provide voltages for the fifth switching element T5, the sixth switching element T6 and the seventh switching element T7, and is matched with the corresponding turn-on voltages received by the corresponding control terminals of the corresponding switching elements to turn on the switching elements. In addition, the first power voltage AVDD1 and the second power voltage AVDD2 of the present embodiment may be two power voltages, but the present embodiment is not limited thereto, and the first power voltage AVDD1 and the second power voltage AVDD2 may also be the same power voltage.
Specifically, only when the first switching control signal S1 and the second switching control signal S2 are simultaneously high level, such that the fifth control terminal of the fifth switching element T5 receives the high level of the first switching control signal S1 to be turned on, and the sixth control terminal of the sixth switching element T6 receives the high level of the second switching control signal S2 to be turned on, the seventh control terminal of the seventh switching element T7 may be grounded to low level through the turned-on fifth switching element T5 and sixth switching element T6, and the seventh switching element T7 is turned off, so that the fourteenth switching terminal of the seventh switching element T7 may not be grounded through the turned-off seventh switching element T7, and the second power supply voltage AVDD2 is received through the fifth resistor R5 to be high level, that is, the fourteenth switching voltage output from the fourteenth switching terminal of the seventh switching element T7 is high voltage.
When either the first switching control signal S1 or the second switching control signal S2 is at a low level, such that the fifth control terminal of the fifth switching element T5 receives a low level of the first switching control signal S1 and is turned off, or the sixth control terminal of the sixth switching element T6 receives a low level of the second switching control signal S2 and is turned off, the seventh control terminal of the seventh switching element T7 may not be grounded through the turned-off fifth switching element T5 or the turned-off sixth switching element T6, and receives the second power voltage AVDD2 through the fourth resistor R4 and is at a high level, the seventh switching element T7 is turned on, such that the fourteenth path terminal of the seventh switching element T7 may be grounded through the turned-on seventh switching element T7, that is, the fourteenth path terminal of the seventh switching element T7 outputs a low voltage.
The Gamma voltage chip 220 receives the first switching control signal S1, and outputs the second Gamma voltage Gamma2 or the third Gamma voltage Gamma3 according to the level of the first switching control signal S1 when the switching signal is at the inactive level, i.e. when the first switching control signal S1 is at the high level, the Gamma voltage chip 220 outputs the second Gamma voltage Gamma2, and when the first switching control signal S1 is at the low level, the Gamma voltage chip 220 outputs the third Gamma voltage Gamma 3. When the switching signal is at the active level, the Gamma voltage chip 220 stops outputting the second group of Gamma voltages Gamma2 or the third group of Gamma voltages Gamma3, specifically, the second control terminal of the second switch element T2 of the embodiment receives the active level to turn off the second switch element T2, the enable terminal of the Gamma voltage chip 220 may not receive the first power voltage AVDD1 through the turned-off second switch element T2, and the enable terminal of the Gamma voltage chip 220 is at the low level, so that the Gamma voltage chip 220 stops outputting the second group of Gamma voltages Gamma2 or the third group of Gamma voltages Gamma 3; in another embodiment, the second control terminal of the second switch element T2 receives an active level to turn on the second switch element T2, the enable terminal of the Gamma voltage chip 220 can receive the first power voltage AVDD1 through the turned-on second switch element T2, and the enable terminal of the Gamma voltage chip 220 is at a high level, so that the Gamma voltage chip 220 stops outputting the second or third set of Gamma voltages Gamma2 or Gamma 3. Meanwhile, when each first switching element T1 receives the active level of the switching signal, each first switching element T1 is turned on, so that the voltage (V1, V2.. V13, V14) between every two adjacent first resistors R1 in the first resistor string 210 can be output to a source driving circuit (not shown in the figure) through the turned-on first switching elements T1, and the voltages V1 to V14 are the first group Gamma voltages Gamma1, that is, the first resistor string 210 outputs the first group Gamma voltages Gamma1 to the source driving circuit through the turned-on first switching elements T1.
Therefore, the gamma voltage switching device of the present embodiment can switch and output three sets of gamma voltages in real time according to the first switching control signal S1 and the second switching control signal S2 (refer to the following table specifically), so as to improve the phenomenon of gray level inversion. However, the present invention is not limited to the case where the first switching control signal S1 and the second switching control signal S2 are both at a high level, and the switching signal is at an active level, for example, in other embodiments, the switching signal may be at an active level when the first switching control signal S1 and the second switching control signal S2 are both at a low level, and accordingly, the Gamma voltage switching device outputs the second Gamma voltage Gamma2 when the first switching control signal S1 is at a low level; when the first switching control signal S1 is at a low level, the Gamma voltage switching device respectively outputs the third Gamma voltage Gamma3 or the first Gamma voltage Gamma1 according to the level of the second switching control signal S2.
The low level in this embodiment is not limited to a voltage close to 0V, but may be a positive voltage at a high level and a negative voltage at a relatively low level.
In one embodiment, the second switching control signal S2 is an ac signal that alternates between high and low levels when switching every frame. Therefore, when the first switching control signal S1 is at a low level, the Gamma voltage switching device outputs a third set of Gamma voltages Gamma 3; when the first switching control signal S1 is at a high level and the second switching control signal S2 is an ac signal that is alternately at a high level and a low level during each frame switching, the Gamma voltage switching device alternately outputs the first Gamma voltage Gamma1 and the second Gamma voltage Gamma2 during each frame switching, thereby better improving the phenomenon of gray scale inversion.
The gamma voltage switching device of the embodiment can provide three groups of gamma voltages to the source electrode driving circuit and can switch the three groups of gamma voltages in real time, thereby improving the phenomenon of gray scale inversion.
Third embodiment
The embodiment also provides a liquid crystal display device, which comprises the gamma voltage switching device.
The liquid crystal display device of the embodiment can provide three groups of gamma voltages to the source electrode driving circuit and can switch the three groups of gamma voltages in real time, thereby improving the phenomenon of gray scale inversion.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A gamma voltage switching apparatus comprising a switching control circuit (100) and a voltage output circuit (200), the switching control circuit (100) being configured to output a switching signal in accordance with a first switching control signal (S1) and a second switching control signal (S2) received; the voltage output circuit (200) comprises:
a first resistor string (210), the first resistor string (210) for generating a first set of gamma voltages, the first resistor string (210) comprising a plurality of first resistors (R1), a first terminal of the first resistor string (210) receiving a first supply voltage (AVDD1), a second terminal of the first resistor string (210) being connected to ground;
a plurality of first switching elements (T1), each first switching element (T1) including a first control terminal, a first pass terminal and a second pass terminal, the first control terminal of each first switching element (T1) receiving the switching signal, the first pass terminal of each first switching element (T1) being respectively connected to a common terminal of every two adjacent first resistors (R1) in the first resistor string (210), the second pass terminal of each first switching element (T1) being connected to a source driving circuit;
a second switching element (T2), the second switching element (T2) including a second control terminal, a third path terminal, and a fourth path terminal, the second control terminal of the second switching element (T2) receiving the switching signal, the third path terminal of the second switching element (T2) receiving the first power voltage (AVDD 1);
a gamma voltage chip (220), wherein the gamma voltage chip (220) includes an enable terminal and a plurality of voltage output terminals, the enable terminal of the gamma voltage chip (220) is connected to the fourth path terminal of the second switching element (T2), and the plurality of voltage output terminals of the gamma voltage chip (220) are respectively connected to the second path terminal of each first switching element (T1) in a one-to-one correspondence;
wherein, when the switching signal is at an inactive level, the gamma voltage chip (220) outputs a second set of gamma voltages or a third set of gamma voltages according to the level of the first switching control signal (S1), and when the switching signal is at an active level, the gamma voltage chip (220) stops outputting the second set of gamma voltages or the third set of gamma voltages, and each first switching element (T1) is turned on, so that the first resistor string (210) outputs the first set of gamma voltages to the source driving circuit through a plurality of first switching elements (T1).
2. The gamma voltage switching device of claim 1, wherein the active level of the switching signal is a high level.
3. The gamma voltage switching apparatus of claim 1, wherein each of the first switching elements (T1) is a TFT transistor integrated on a source driving board.
4. The gamma voltage switching apparatus of claim 1, wherein the second switching control signal (S2) is an alternating current signal alternately high and low for every frame switching.
5. The gamma voltage switching apparatus of claim 1, wherein the switching control circuit (100) comprises:
a third switching element (T3), the third switching element (T3) including a third control terminal, a fifth pass terminal and a sixth pass terminal, the third control terminal of the third switching element (T3) receiving the first switching control signal (S1), the sixth pass terminal of the third switching element (T3) being grounded;
a fourth switching element (T4), the fourth switching element (T4) including a fourth control terminal, a seventh path terminal, and an eighth path terminal, the fourth control terminal of the fourth switching element (T4) being connected to the fifth path terminal of the third switching element (T3), the seventh path terminal of the fourth switching element (T4) receiving the second switching control signal (S2), the eighth path terminal of the fourth switching element (T4) outputting the switching signal;
a second resistor (R2), a first terminal of the second resistor (R2) being connected to the seventh path terminal of the fourth switching element (T4), a second terminal of the second resistor (R2) being connected to the fifth path terminal of the third switching element (T3);
a third resistor (R3), a first terminal of the third resistor (R3) being connected to the eighth path terminal of the fourth switching element (T4), and a second terminal of the third resistor (R3) being grounded.
6. The gamma voltage switching device of claim 5, wherein each of the first switching elements (T1) is an N-type TFT transistor, the second switching element (T2) and the fourth switching element (T4) are PMOS transistors, and the third switching element (T3) is an NMOS transistor.
7. The gamma voltage switching apparatus of claim 1, wherein the switching control circuit (100) comprises:
a fifth switching element (T5), the fifth switching element (T5) including a fifth control terminal, a ninth path terminal and a tenth path terminal, the fifth control terminal of the fifth switching element (T5) receiving the first switching control signal (S1), the tenth path terminal of the fifth switching element (T5) being grounded;
a sixth switching element (T6), the sixth switching element (T6) including a sixth control terminal, an eleventh path terminal, and a tenth path terminal, the sixth control terminal of the sixth switching element (T6) receiving the second switching control signal (S2), the tenth path terminal of the sixth switching element (T6) being connected to the ninth path terminal of the fifth switching element (T5);
a seventh switching element (T7), the seventh switching element (T7) including a seventh control terminal, a tenth path terminal and a tenth path terminal, the seventh control terminal of the seventh switching element (T7) being connected to the eleventh path terminal of the sixth switching element (T6), the thirteenth path terminal of the seventh switching element (T7) outputting the switching signal, the tenth path terminal of the seventh switching element (T7) being grounded;
a fourth resistor (R4), a first terminal of the fourth resistor (R4) receiving a second power supply voltage (AVDD2), a second terminal of the fourth resistor (R4) being connected to an eleventh path terminal of the sixth switching element (T6);
a fifth resistor (R5), a first terminal of the fifth resistor (R5) receiving the second power supply voltage (AVDD2), a second terminal of the fifth resistor (R5) being connected to a tenth switching terminal of the seventh switching element (T7).
8. The gamma voltage switching device of claim 7, wherein each of the first switching elements (T1) is an N-type TFT transistor, the second switching element (T2) is a PMOS transistor, and the fifth switching element (T5), the sixth switching element (T6) and the seventh switching element (T7) are NMOS transistors.
9. A liquid crystal display device including a gate driver circuit, characterized in that the liquid crystal display device includes the gamma voltage switching device according to any one of claims 1 to 8.
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| TWI307075B (en) * | 2005-01-06 | 2009-03-01 | Novatek Microelectronics Corp | Method and device for the compensation of gray level luminance |
| CN1937025B (en) * | 2005-09-23 | 2011-11-23 | 奇美电子股份有限公司 | Grey-to-grey voltage generating circuit for plane display and operation method |
| TW201239845A (en) * | 2011-02-14 | 2012-10-01 | Samsung Electronics Co Ltd | Systems and methods for driving a display device |
| CN103745695B (en) * | 2013-12-02 | 2016-03-30 | 深圳市华星光电技术有限公司 | Gamma Voltag driving circuit, source drive module and liquid crystal panel |
| CN105261336B (en) * | 2014-05-30 | 2018-01-30 | 奇景光电股份有限公司 | Gamma voltage producing circuit |
| TWI527020B (en) * | 2015-01-07 | 2016-03-21 | 友達光電股份有限公司 | Circuit and method for generating gamma voltage |
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