Reduce the method and the circuit of liquid crystal display panel flicker
Technical field
The present invention relates to LCD (LCD, liquid crystal display), especially a kind of method and circuit that reduces liquid crystal display panel flicker adjusted the phenomenon of circuit (modulation circuit) to panel of LCD and then reduction LCD generation panel flash (flicker) by increasing.
Background technology
LCD is more and more welcome in recent years, not only saves the space and also saves energy.The LCD of large scale, high-res is in order to substitute traditional display, for example, and cathode-ray tube display (CRT display).Yet large-sized LCD has a problem, and size is bigger, and the panel flash problem of LCD is more serious.
Because liquid crystal cells (liquid crystal) can produce along with long bias voltage and electrically dissociate, the type of drive of therefore general LCD is to exchange (AC) to drive, and promptly data signal (datasignal) drives contact variation between (negative region) in forward drive (positive region) and negative sense.Fig. 1 a is the method for the reverse drive of general LCD."+" expression forward drive, "-" expression negative sense drives.The AC driving of LCD can be divided into four kinds of modes: the width of cloth is reverse oppositely (columninversion) and the point oppositely (dot inversion) of (row inversion), row of (frame inversion), row oppositely.In addition, the voltage quasi position of sweep signal also has the state more than two.For example, the voltage quasi position of sweep signal is ternary, is respectively the accurate position of high voltage Vhigh, low-voltage accurate position Vlow and the accurate position of bucking voltage Vgc, and the accurate position of its low-voltage Vlow is between accurate Vhigh of high voltage and the accurate Vgc of bucking voltage.
Fig. 1 b is the summary construction diagram of known LCD.LCD is made of scanner driver 10, data driver 22 and display panels.Wherein, display panels comprises crisscross data line and sweep trace, and staggered data line and the sweep trace of each group can be used for controlling a display unit (display unit).Wherein, if an end of display unit is linked to the common voltage source that the accurate position of common voltage Vcom is provided in addition, this structure is called capacitive coupling common source (CS onCommon) structure; If an end of display unit is linked to another sweep trace in addition, provide voltage quasi position by another sweep trace, this structure is called capacitive coupling grid (CS on Gate) structure, and this figure is an example with the capacitive coupling grid structure.For example, data line 18a and sweep trace 20b can be used for controlling display unit 13, and wherein, the circuit of display unit 13 comprises transistor 12ba, electric capacity 14ba and liquid crystal cells (liquid crystal) 16ba.The grid of transistor 12ba is connected sweep trace 20b and data line 18a respectively with drain electrode, by the On/Off state of the sweep signal oxide-semiconductor control transistors 12ba on the sweep trace 20b, in the electric capacity 14ba and 16ba that will write display unit 13 at the data signal on the data line 18a.Electric capacity is with store data signal and drive liquid crystal cells 16ba with this data signal of voltage quasi position.The other end of electric capacity 14ba is coupled to sweep trace 20a, and when activation sweep trace 20b, sweep trace 20a is provided a voltage quasi position.Scanner driver (scan driver) 10 is sent each sweep trace 20a, 20b in regular turn ... sweep signal on the 20m makes and is only opening a certain transistor that lists all display units together in a flash, and closes the transistor that other list all display units.When the transistor of all display units of row was all opened, 22 of data drivers (data driver) were according to image data to be shown, via data line 18a, 18b ... 18n sends corresponding data signal to the display unit of these row.Therefore, each sweep trace of multiple scanning and send data signal just can reach the purpose of show image.Yet each sweep trace is all electric wire with impedance and a plurality of electric capacity by a plurality of transistor couplings so far in the sweep trace.Therefore, sweep signal will be subjected to that resistance capacitance effect (R-Ceffect) influences and the waveform that changes sweep signal.For example, originally the sweep signal on sweep trace 20b is come On/Off transistor 12ba with normal waveform, but comes On/Off transistor 12bn with the distorted waveform that is subjected to the resistance capacitance effect and is influenced.Though normal waveform and distorted waveform can provide similar function, are not just the same.Therefore, electric capacity 16ba stores normal data signal, but electric capacity 16bn stores the data signal of distortion, so, the correct data signal and the data signal of distortion are in the difference that produces on the LCD on brightness or the color, and the difference on this brightness or the color can cause the user to produce the illusion of liquid crystal display panel flicker because of the variation of positive negative cycle.Along with the large-size LCD is operated under the higher frequency of operation, it is more serious that the panel flash problem of LCD also will show.
Summary of the invention
In view of this, the present invention proposes a kind of method and circuit that reduces liquid crystal display panel flicker, to reduce the flicker problem of panel of LCD panel.
For reaching the purpose of the invention described above, the present invention proposes a kind of adjustment circuit, in order to reduce the flicker of display panels, comprising: a variable resistor; And a plurality of transistors, be coupled to an end of the multi-strip scanning line same side of above-mentioned display panels one to one, each above-mentioned transistor has a power end that is coupled to a control end of a voltage source and is coupled to a common voltage source by above-mentioned variable resistor; Wherein, by changing above-mentioned variable-resistance resistance, with each above-mentioned transistorized impedance of modulation.
For reaching another object of the present invention, the present invention proposes a kind of display panels, comprising: multi-strip scanning line and many data lines, and the formation array is staggered; A plurality of display units are arranged at each staggered place of above-mentioned sweep trace and above-mentioned data line; The data driver couples above-mentioned data line; Scanner driver couples first end of each above-mentioned sweep trace; One variable resistor; And a plurality of transistors, being coupled to second end of above-mentioned sweep trace one to one, each above-mentioned transistor has a power end that is coupled to a control end of a voltage source and is coupled to a common voltage source by above-mentioned variable resistor; Wherein, by changing above-mentioned variable-resistance resistance, with each above-mentioned transistorized impedance of modulation.
The present invention also proposes a kind of method that reduces the display panels flicker, and it comprises the following step: first end that a plurality of transistors is coupled to one to one the multi-strip scanning line of above-mentioned panel; By a variable resistor each above-mentioned transistorized control end is coupled to a direct current voltage source; An above-mentioned transistorized voltage end is coupled to a common voltage source; And change above-mentioned variable-resistance resistance, with each above-mentioned transistorized impedance of modulation, to reduce the flicker of above-mentioned panel.
The present invention reduces the situation that produces panel flash because of the delay of sweep signal by increasing by an adjustment circuit, makes LCD can be operated in upper frequency.
Description of drawings
Fig. 1 a is the method for the AC driving of general LCD;
Fig. 1 b is the summary construction diagram of known LCD;
Fig. 2 is the summary construction diagram of preferred embodiment LCD; And
Fig. 3 reduces the panel flash method flow diagram of LCD for preferred embodiment.
Embodiment
Fig. 2 is the summary construction diagram of preferred embodiment LCD.LCD is made up of scanner driver 30, data driver 48, crisscross data line 38a-38n, sweep trace 42a-42m, display unit 33 and adjustment circuit 50.Scanner driver 30 is in order to choose wherein one scan line, and data driver 48 is chosen a display unit in order to choose a wherein data line by choosing suitable data line and sweep trace.In addition, the other end of all sweep traces is linked to and adjusts circuit 50.For example, choose data line 38a and sweep trace 40b just can choose display unit 33.The circuit of display unit 33 comprises transistor 32ba, electric capacity 34ba and liquid crystal cells 36ba.The grid of transistor 32ba is connected sweep trace 40b and data line 38a respectively with drain electrode, come the On/Off state of oxide-semiconductor control transistors 32ba by the sweep signal on the sweep trace 40b, in the electric capacity 34ba and liquid crystal cells 36ba that the data signal on the data line 38a are write display unit 33.Electric capacity 34ba is with store data signal and drive liquid crystal cells 36ba with this data signal of voltage quasi position.The other end of electric capacity 34ba is coupled to sweep trace 40a.When activation sweep trace 40b, the sweep trace 40a voltage Vgc that afforded redress.Adjust circuit 50 and have variable resistor 44 and a plurality of impedance adjusting gear 42a-42m, and impedance adjusting gear 42a-42m is a transistor.The common voltage source that the control end of a plurality of impedance adjusting gear 42a-42m, scanning line end and power end are coupled respectively to variable resistor 44, sweep trace and common voltage Vcom is provided.The DC voltage that direct voltage source 46 provides through behind the variable resistor 44, provide a driving voltage in order to driving each impedance adjusting gear 42a-42m, and the impedance of each impedance adjusting gear 42a-42m is much larger than the impedance of each sweep trace.Scanner driver 30 is sent each sweep trace 40a, 40b in regular turn ... sweep signal on the 40m makes and is only opening a certain transistor that lists all display units together in a flash, and closes the transistor that other list all display units.When the transistor of all display units of row was all opened, 22 of data drivers were according to image data to be shown, via data line 18a, 18b ... 18n sends corresponding data signal to the display unit of these row.Because the impedance that the impedance adjusting gear is provided is much larger than sweep trace, therefore, the impedance that sweep trace itself is had seems small and ignores that in comparison, the resistance capacitance effect also seems small ignoring.Therefore, under identical condition, the sweep signal on the sweep trace 40b drives electric capacity 34ba and electric capacity 34bn with the sweep signal more close than known techniques.List the reference data that measures at this.When forward drive, the voltage quasi position of the data signal that the electric capacity 14ba of known techniques and electric capacity 14bn are stored differs 45 millivolts (electric capacity with voltage quasi position store data signal), and the voltage quasi position of the stored data signal of the electric capacity 34ba of embodiment and electric capacity 34bn differs 24.8 millivolts; When negative sense drove, the voltage quasi position of the data signal that the electric capacity 14ba of known techniques and electric capacity 14bn are stored differed 160 millivolts, and the voltage quasi position of the stored data signal of the electric capacity 34ba of embodiment and electric capacity 34bn differs 45 millivolts.The data signal stored owing to electric capacity is more known more close, so the difference that LCD produces on brightness or the color is small than known techniques, the liquid crystal display panel flicker problem is improved.
Fig. 3 prevents the panel flash method flow diagram of LCD for preferred embodiment, and makes correspondence with Fig. 2.And the method for embodiment comprises:
Step 100: first end that a plurality of impedance adjusting gears is coupled to one to one the multi-strip scanning line of panel.Adjust impedance adjusting gear 42a, 42b in the circuit 50 ... the scanning end of 42m is coupled to wherein one scan line.
Step 110: the control end of each impedance adjusting gear is coupled to direct voltage source by variable resistor.Adjust impedance adjusting gear 42a, 42b in the circuit 50 ... the control end of 42m is coupled to variable resistor 44, and variable resistor 44 is coupled to direct voltage source 46.
Step 120: the voltage end of impedance adjusting gear is coupled to common voltage source.Adjust impedance adjusting gear 42a, 42b in the circuit 50 ... the voltage end of 42m is coupled to the common voltage source that common voltage Vcom is provided.
Step 130: change variable-resistance resistance, with the impedance of each impedance adjusting gear of modulation, to reduce the flicker of panel.By changing the impedance of variable resistor 44, make impedance adjusting gear 42a, 42b ... the impedance of 42m is greater than the impedance of sweep trace, and the impedance that sweep trace itself is had seems small and ignores, and eliminates the resistance capacitance effect by this.
Though the present invention discloses as above with preferred embodiment; right its is not in order to qualification the present invention, any those who are familiar with this art, without departing from the spirit and scope of the invention; when can doing a little change and retouching, so the present invention's protection domain is as the criterion when looking claims scope person of defining.