CN100495128C - Gamma reference voltage generation circuit - Google Patents
Gamma reference voltage generation circuit Download PDFInfo
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- CN100495128C CN100495128C CNB2006100786575A CN200610078657A CN100495128C CN 100495128 C CN100495128 C CN 100495128C CN B2006100786575 A CNB2006100786575 A CN B2006100786575A CN 200610078657 A CN200610078657 A CN 200610078657A CN 100495128 C CN100495128 C CN 100495128C
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- 239000004973 liquid crystal related substance Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- 238000002834 transmittance Methods 0.000 claims description 6
- 239000010409 thin film Substances 0.000 description 11
- 239000003990 capacitor Substances 0.000 description 9
- 230000005540 biological transmission Effects 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 241001270131 Agaricus moelleri Species 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
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Abstract
This invention discloses one Gamma reference voltage generation circuit for film transistor LCD, which comprises direct stable voltage, positive gamma reference voltage generation circuit and is characterized by the following: the said reference voltage generate circuit output end is connected with switch and reverse charge pump circuit to form negative Gamma reference generation circuit; according to LCD symmetric voltage to transparence property curve by simple circuit and positive Gamma reference voltage to Gamma reference voltage.
Description
Technical field
The present invention relates to a kind of Thin Film Transistor-LCD (TFT-LCD), relate in particular to gamma (GAMMA) generating circuit from reference voltage of Thin Film Transistor-LCD.
Background technology
Lcd technology develops very soon, because it is in light weight, liquid crystal display device is widely used in various demonstrations field.
Gamma reference voltage generation circuit is as an important component part of Thin Film Transistor-LCD module, the gray scale of Thin Film Transistor-LCD regulated playing crucial effects.The effect of gamma reference voltage generation circuit is according to desired gamma curve, sets gamma reference voltage GMA1, GMA2 or the like, carries out the reference voltage that gray scale shows as Thin Film Transistor-LCD.For example, the gamma reference voltage of zone of positive pressure be GMA1 to GMA5, the gamma reference voltage of negative pressuren zone be GMA6 to GMA10, set a gamma reference voltage every 16 gray scales.Each gamma reference voltage is input in the signal drive circuit of Thin Film Transistor-LCD, the digital to analog converter through signal drive circuit produces all grayscale voltages.Thereby make the gray scale of Thin Film Transistor-LCD module and the gamma curve that transmittance curve simulates requirement.
According to the voltage-transmittance curve of liquid crystal material, by calculating each gamma reference voltage value, use gamma reference voltage generation circuit to produce these gamma reference voltages then, offer signal drive circuit.Existing gamma reference voltage generation circuit as shown in Figure 1.
The direct-flow steady voltage VDD that provides by power supply, time branch hydraulic circuit on Fig. 1 right side is by gamma resistance string R0, a R1 ... R5-1, R5-2 ... R9, R10 produce each gamma reference voltage, and the main hydraulic circuit that divides in Fig. 1 left side is a mu balanced circuit with feeding back operational amplification circuit, GMA3, the GMA5.5 of stable time bleeder circuit and the magnitude of voltage of GMA8.
The major defect of prior art is: determining of gamma resistance value is very loaded down with trivial details, different LCD panel of thin-film transistor need be regulated with different gamma resistance values with different liquid crystal material characteristics, so needing has influenced engineering technical personnel's work efficiency greatly by a large amount of calculating and debugging work.And each gamma reference voltage value will be input on the pin of respective signal driving circuit respectively, and often in order to improve the gray scale display characteristic, can increase the number of gamma reference voltage, prior art need increase the signal drive circuit input pin of respective number, therefore be unfavorable for the integrated of signal drive circuit, display resolution is restricted.
Summary of the invention
The objective of the invention is defective at prior art, and fringe field switching type (FFS) waits the employed liquid crystal material of this class Thin Film Transistor-LCD to have the characteristics of symmetry voltage-transmittance curve as shown in Figure 2, a kind of new gamma reference voltage generation circuit is provided, significantly reduce the workload of gamma resistance debugging, reduce the gamma reference voltage input pin number of signal drive circuit.
To achieve these goals, the invention provides a kind of gamma reference voltage generation circuit, comprise: direct-flow steady voltage, the zone of positive pressure gamma reference voltage generation circuit, it is characterized in that: described zone of positive pressure gamma reference voltage generation circuit output terminal is connected with the negative pressuren zone gamma reference voltage generation circuit that is made of switch and reversed charge pump circuit, described switch is the binary states switch by high-frequency square-wave signal control, when square wave is positioned at first level state, and switch connection zone of positive pressure gamma reference voltage; When square wave is positioned at second level state, switch ground connection; Described reversed charge pump circuit is made of two electric capacity and two diodes; Wherein an end of first electric capacity is connected with described binary states switch, and the other end is connected with the P utmost point of the PN junction of first diode, and the N utmost point of while with the PN junction of second diode is connected; The N utmost point of first diode is connected to reference voltage; The P utmost point of second diode is connected with second electric capacity one end; The other end of second electric capacity is connected to reference voltage.The frequency of described high-frequency square-wave signal is more than or equal to 50kHz.Described high-frequency square-wave signal is produced by the clock control device of driving circuit.
Gamma reference voltage generation circuit of the present invention only need be regulated the gamma resistance value that is used to produce symmetrical voltage-transmittance curve zone of positive pressure gamma reference voltage, and the circuit that constitutes by above-mentioned switch and reversed charge pump circuit automatically produces the corresponding gamma reference voltage of negative pressuren zone, the workload of gamma resistance debugging is reduced to half of prior art workload.
In addition, circuit by zone of positive pressure gamma reference voltage generation negative pressuren zone gamma reference voltage of the present invention can be built in the signal drive circuit, the input end of signal drive circuit just only need provide zone of positive pressure gamma reference voltage pin to get final product like this, so the gamma reference voltage input pin number of signal drive circuit has also reduced accordingly.
Gamma reference voltage generation circuit among the present invention is made of switch and reversed charge pump circuit, and more existing homogeneous circuit is greatly simplified, and this has reduced the area and the power consumption of circuit.Circuit owing to employing is simple in addition, and does not rely on circuit element parameter, and the circuit precision is improved.
Various advantage of the present invention will more clearly embody in specific embodiment.
Description of drawings
Fig. 1 is previous a kind of gamma reference voltage generation circuit;
Fig. 2 is a kind of symmetry voltage-light transmission rate curve of liquid crystal material;
Fig. 3 is the synoptic diagram of gamma reference voltage generation circuit of the present invention;
Fig. 4 is in the gamma reference voltage generation circuit of the present invention, utilizes the zone of positive pressure gamma reference voltage to produce the structural drawing of the circuit part of negative pressuren zone gamma reference voltage;
Signal schematic representation when Fig. 5 is a circuit working in the embodiment of the invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is further elaborated.
A kind of liquid crystal material that is used for Thin Film Transistor-LCD has symmetry voltage-light transmission rate curve as shown in Figure 2.Determine each gamma reference voltage value according to described family curve and desired gray scale.Be followed successively by GMA1, GMA2, GMA3, GMA4, GMA5 if determine the gamma reference voltage value of zone of positive pressure, so because symmetric voltage-light transmission rate curve, negative pressuren zone gamma reference voltage value GMA6, GMA7, GMA8, GMA9, GMA10 and zone of positive pressure gamma reference voltage value GMA1, GMA2, GMA3, GMA4, GMA5, with respect to the symcenter voltage VCNETER of voltage-light transmission rate curve, mirror image each other.That is:
GMA1+GMA10＝2VCNETER
GMA2+GMA9＝2VCNETER
GMA3+GMA8＝2VCNETER
GMA4+GMA7＝2VCNETER
GMA5+GMA6＝2VCNETER
So, utilize the left-hand component circuit of Fig. 3 to determine that the gamma reference voltage value of zone of positive pressure is followed successively by after GMA1, GMA2, GMA3, GMA4, the GMA5, can produce corresponding negative pressuren zone gamma reference voltage GMA6, GMA7, GMA8, GMA9, GMA10 by circuit 101 by the negative pressuren zone gamma reference voltage on Fig. 3 the right.
The left-hand component circuit of Fig. 3, be to produce corresponding zone of positive pressure gamma reference voltage GMA1 to GMA5 by time branch hydraulic circuit of forming by resistance string R0, R1, R2, R3, R4, R5 with direct-flow steady voltage VDD, simultaneously by the main pressure stabilization function that divides hydraulic circuit and feedback operational amplification circuit, the zone of positive pressure gamma reference voltage GMA2 and the GMA4 of stable time bleeder circuit.To Fig. 3 right-hand component circuit, promptly negative pressuren zone gamma reference voltage generation circuit 101 is described in detail below.
As shown in Figure 4, the negative pressuren zone gamma reference voltage generation circuit is by binary states switch T1 and T1, and the reversed charge pump circuit constitutes.
Wherein, binary states switch T1 and T1 are controlled by high-frequency square-wave signal, and the frequency of high-frequency square-wave signal is more than or equal to 50kHz, and can be easily produced by the control devices such as clock controller of driving circuit.When high-frequency square-wave signal is positioned at as shown in Figure 5 high level state, switch T1 conducting, switch T1 ends, and on-off circuit is connected the zone of positive pressure gamma reference voltage; When high-frequency square-wave signal is positioned at as shown in Figure 5 low level state, switch T1 conducting, switch T1 ends, on-off circuit ground connection.The reversed charge pump circuit is made of two electric capacity and two diodes; Wherein an end of capacitor C 1 is connected with T1 with binary states switch T1, and the other end is connected with the P utmost point of diode D1, is connected with the N utmost point of diode D2 simultaneously; The N utmost point of the D1 of diode is connected to reference voltage; The P utmost point of diode D2 is connected with an end of capacitor C 2; The other end of capacitor C 2 is connected to reference voltage.The T1 input of zone of positive pressure gamma reference voltage from the binary states switch, corresponding negative pressuren zone gamma reference voltage is from the P utmost point one end output of the D2 of anti-phase charge pump.Wherein, the time constant of reversed charge pump circuit is much larger than the cycle of high-frequency square-wave signal.
Below in conjunction with the principle of work of reversed charge pump circuit, be described further by the detailed operation principle that the zone of positive pressure gamma reference voltage obtains the negative pressuren zone gamma reference voltage utilizing negative pressuren zone gamma reference voltage generation circuit 101 in this specific embodiment.
Reversed charge pump ultimate principle is that the bias state of diode keeps partially anti-, to realize the maintenance of electric charge on the electric capacity.Because the state of high-frequency square-wave signal control binary states switch T1 and T1, the current potential Va that a is ordered among Fig. 4 is with the frequency change identical with high-frequency square-wave signal, as shown in Figure 5.When circuit is in first cycle that T1 closure and T1 disconnect, the current potential Va=GMA1 that a order considers that diode D1 need keep anti-inclined to one side, C1 could keep electric charge, therefore the b current potential of ordering is no more than Vb=V1-VD, and wherein V1 is a reference voltage, and VD is the threshold voltage of diode.Because what the C1 charging utilized is the reverse leakage current of diode D1, so charging rate is slow, still experiences first cycle that a plurality of T1 closures and T1 disconnect, the current potential that last b is ordered always can be charged to V1-VD.After finishing above-mentioned charging process, the voltage difference at C1 two ends can reach V1-VD-GMA1 in first cycle.At this moment enter second cycle of T1 closure and T1 disconnection when circuit, the current potential Va=0 that a is ordered, because the time constant of reversed charge pump circuit is much larger than the cycle of high-frequency square-wave signal, the voltage difference at C1 two ends still is V1-VD-GMA1, the b current potential of ordering is pulled low to Vb=V1-VD-GMA1＜V1-VD so, capacitor C 1 will continue charging like this, it is same because what utilize is that the reverse leakage current of diode D1 charges, charging rate is slow, in this time half period, C1 both end voltage difference only increases Δ V in a small amount, and the voltage difference at capacitor C 1 two ends becomes V1-VD-GMA1+ Δ V.Half period in ensuing T1 closure and T1 disconnection, the current potential Vb=V1-VD+ Δ V that the current potential Va=GMA1 that a is ordered, b are ordered〉V1-VD, so capacitor C 1 meeting discharge, the current potential that b is ordered is got back to Vb=V1-VD.If ignore a small amount of fluctuation Δ V of above-mentioned voltage difference, the voltage difference at capacitor C 1 two ends is basicly stable to be V1-VD-GMA1, does not change in time, so the current potential that b is ordered is followed the current potential that a is ordered, with the frequency identical, on Vb=V1-VD and two level of V1-VD-GMA1, change with high-frequency square-wave signal.
When b point current potential is Vb=V1-VD-GMA1, it is partially anti-to consider that equally diode D2 needs, capacitor C 2 could keep electric charge, therefore be pulled to GMA10=V1-2VD-GMA1 when the c current potential of ordering is stablized, work as b point current potential subsequently and become Vb=V1-VD, diode is still anti-partially, so the state of charge on the capacitor C 2 do not change, and the c current potential of ordering still stabilizes to GMA10=V1-2VD-GMA1 so.The c current potential GMA10 of ordering is time-independent single level like this.
If set reference voltage V 1=2VCENTER+2VD, so GMA10=2VCNETER-GMA1.So just realized producing the function of negative pressuren zone gamma reference voltage GMA10 by zone of positive pressure gamma reference voltage GMA1.Same method can produce corresponding negative pressuren zone gamma reference voltage by other zone of positive pressure gamma reference voltages, promptly produces GMA9, GMA3 by GMA2 and produces GMA8, GMA4 generation GMA7 and GMA5 generation GMA6.
As shown in Figure 3, be used to produce the gamma resistance value R0 to R5 of symmetrical voltage-transmittance curve zone of positive pressure gamma reference voltage in the present embodiment by debugging, just distinguished the circuit 101 that constitutes by above-mentioned switch and reversed charge pump circuit behind GMA1, GMA2, GMA3, GMA4, the GMA5 and automatically produced the corresponding gamma reference voltage GMA10 of negative pressuren zone, GMA9, GMA8, GMA7, GMA6, compared with prior art, need the quantity of the gamma resistance of debugging to reduce half.
Equally, the circuit that the present invention describes can be built in the signal drive circuit, and the input end of signal drive circuit just only need provide zone of positive pressure gamma reference voltage pin to get final product like this, and compared with prior art, number of pins reduces half.In the present embodiment be 5, so the input end number of pins of signal drive circuit has also reduced 5 accordingly.
In addition, gamma reference voltage generation circuit of the present invention is greatly to be simplified by the more existing homogeneous circuit of circuit that switch and reversed charge pump circuit constitute, and this has reduced the area and the power consumption of circuit.Circuit owing to employing is simple in addition, and does not rely on circuit element parameter, and the circuit precision is improved, and the gamma reference voltage precision of generation also improves thereupon.
Present embodiment only is used to illustrate rather than limit the gamma reference voltage generation circuit of Thin Film Transistor-LCD driving circuit of the present invention.Part unless otherwise indicated, the present invention is not limited to the detail of foregoing description.As according to quantity of gray shade scale conversion gamma reference voltage etc.Under the prerequisite that does not depart from the circuit essential characteristics, the present invention also has other specific embodiment.Any modifications and variations that meet feature of the present invention, all within the scope of the present invention.
Claims (4)
1, a kind of gamma reference voltage generation circuit, comprise: direct-flow steady voltage, the zone of positive pressure gamma reference voltage generation circuit, it is characterized in that: described zone of positive pressure gamma reference voltage generation circuit output terminal is connected with the negative pressuren zone gamma reference voltage generation circuit that is made of switch and reversed charge pump circuit, described switch is the binary states switch by high-frequency square-wave signal control, when square wave is positioned at first level state, switch connection zone of positive pressure gamma reference voltage; When square wave is positioned at second level state, switch ground connection; Described reversed charge pump circuit is made of two electric capacity and two diodes; Wherein an end of first electric capacity is connected with described binary states switch, and the other end is connected with the P utmost point of the PN junction of first diode, and the N utmost point of while with the PN junction of second diode is connected; The N utmost point of first diode is connected to reference voltage; The P utmost point of second diode is connected with second electric capacity one end; The other end of second electric capacity is connected to reference voltage.
2, a kind of gamma reference voltage generation circuit according to claim 1, it is characterized in that: the frequency of described high-frequency square-wave signal is more than or equal to 50kHz.
3, a kind of gamma reference voltage generation circuit according to claim 1 is characterized in that: described high-frequency square-wave signal is produced by the clock control device of driving circuit.
4, a kind of gamma reference voltage generation circuit according to claim 1 is characterized in that: described reference voltage is liquid crystal material voltage and the symcenter voltage of transmittance curve and the diode threshold voltage sum of twice of twice.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100786575A CN100495128C (en) | 2006-04-30 | 2006-04-30 | Gamma reference voltage generation circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2006100786575A CN100495128C (en) | 2006-04-30 | 2006-04-30 | Gamma reference voltage generation circuit |
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| CN101063754A CN101063754A (en) | 2007-10-31 |
| CN100495128C true CN100495128C (en) | 2009-06-03 |
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| CNB2006100786575A Expired - Fee Related CN100495128C (en) | 2006-04-30 | 2006-04-30 | Gamma reference voltage generation circuit |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101290756B (en) * | 2008-06-25 | 2010-09-29 | 昆山龙腾光电有限公司 | Gamma voltage generating device, liquid crystal display device and method for controlling gamma voltage |
| CN101882417B (en) * | 2010-07-06 | 2013-03-06 | 华映光电股份有限公司 | Display device and gamma voltage generator |
| CN103366667B (en) * | 2013-07-01 | 2016-03-30 | 北京京东方光电科技有限公司 | Gamma voltage generation circuit and control method |
| CN104036742B (en) | 2014-05-26 | 2016-07-20 | 京东方科技集团股份有限公司 | Gamma reference voltage generation circuit, V-T curve method of testing and display device |
| US10162377B2 (en) | 2015-06-15 | 2018-12-25 | Micron Technology, Inc. | Apparatuses and methods for providing reference voltages |
| US10168724B2 (en) | 2015-06-15 | 2019-01-01 | Micron Technology, Inc. | Apparatuses and methods for providing reference voltages |
| CN107492358B (en) * | 2017-09-14 | 2020-02-21 | 京东方科技集团股份有限公司 | Gamma reference voltage generation circuit and generation method thereof |
| CN110085187B (en) * | 2019-05-05 | 2022-04-01 | Tcl华星光电技术有限公司 | Method and device for selecting resistance value of Gamma circuit |
| CN110379396B (en) * | 2019-06-17 | 2022-03-25 | 北京集创北方科技股份有限公司 | Gamma voltage generation method, generation circuit, source electrode driving circuit, driving chip and display device |
| CN112669786A (en) * | 2021-01-11 | 2021-04-16 | 北京京东方技术开发有限公司 | Gamma circuit, driving method thereof and display panel |
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Effective date of registration: 20071019 Address after: No. 8 West Central Road, Beijing economic and Technological Development Zone Applicant after: BEIJING BOE OPTOELECTRONICS TECHNOLOGY Co.,Ltd. Co-applicant after: BOE TECHNOLOGY GROUP Co.,Ltd. Address before: No. 10 Jiuxianqiao Road, Beijing, Chaoyang District Applicant before: BOE TECHNOLOGY GROUP Co.,Ltd. |
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