CN102857780A - Control method and device for improving light transmittance of 3D (three-dimensional) television - Google Patents

Abstract

The embodiment of the invention discloses a control method and device for improving a light transmittance of a 3D (three-dimensional) television. The control method comprises the steps of receiving a 3D image signal; carrying out field scanning on a displayed last image frame for displaying a current image frame of the 3D signal by a liquid crystal display device, extracting a field synchronizing signal from the current image frame; generating a PWM (Pulse Width Modulation) control signal according to the field synchronizing signal; and when liquid crystal molecules rapidly reach a preset reversal rate due to rapid reversal in a process of displaying the current image frame, enabling light rays generated by a backlight module under the control of the PWM control signal to transmit through the liquid crystal molecules. According to the scheme provided by the embodiment of the invention, when the liquid crystal molecules rapidly reach the presser reversal rate due to rapid reversal in the process of displaying the current image frame, the light rays generated by the backlight module under the control of the PWM control signal transmit through the liquid crystal molecules, thus the 3D crosstalk is lowered.

Description

Improve control method and the device of 3D TV light transmittance

Technical field

The present invention relates to 3D(three-dimensional, three-dimensional) TV domain, relate in particular to a kind of control method and device of the 3D of raising TV light transmittance.

Background technology

The basic principle that the 3D TV shows is to utilize binocular parallax, allows right and left eyes watch respectively the slightly different image of two width of cloth, produces three-dimensional sensation through corticocerebral combined reaction.Flat-panel screens realizes that the condition of 3D effect has: the image that provides two-way to separate fully for right and left eyes; Correct parallax is set between the two-way image.

On the index of 3D effect is mainly manifested in brightness and crosstalks.Crosstalking is human eye when watching the 3D image, and right and left eyes is seen the ratio of wrong image brilliance and correct image brilliance.Take left eye as example, when left eye sees that the image that right eye should be seen namely is wrong image.

Affect the 3D liquid crystal response speed that a topmost factor is panel of crosstalking, it is too high that response time long will directly cause crosstalking, thereby affect subjective effect.

Shutter type 3 D spectacles is present main way.There is aforesaid crosstalk phenomenon defective.

Summary of the invention

For the problems referred to above, the purpose of the embodiment of the invention is to provide and reduces method and the device that method that method that 3D TV left eye crosstalks and device, reduction 3D TV right eye crosstalk and device, reduction 3D TV are crosstalked.

First aspect, the embodiment of the invention provide a kind of control method of the 3D of raising TV light transmittance, and described method comprises: receive the 3D rendering signal; Liquid crystal indicator carries out the current image frame that field scan shows described 3D signal from a upper picture frame that shows, and extracts field sync signal from described current image frame; Generate PWM(Pulse Width Modulation, pulse width modulation according to described field sync signal) control signal; When liquid crystal molecule in showing the process of current image frame because quick counter-rotating reaches rapidly when presetting the counter-rotating rate, backlight module under the control of described pwm control signal the luminous light that produces from described liquid crystal molecule transmission.

Second aspect, the embodiment of the invention provide a kind of control device of the 3D of raising TV light transmittance, and described device comprises: receiving element is used for receiving the 3D rendering signal; Display unit is used for liquid crystal indicator and carries out the current image frame that field scan shows described 3D signal from a upper picture frame that shows, and extract field sync signal from described current image frame; Generation unit is used for generating pwm control signal according to described field sync signal; Transmission units is used for reaching rapidly because reversing fast when presetting the counter-rotating rate in the process that shows current image frame when liquid crystal molecule, backlight module under the control of described pwm control signal the luminous light that produces from described liquid crystal molecule transmission.

The scheme of the embodiment of the invention, by reaching rapidly when presetting the counter-rotating rate because of quick counter-rotating in showing the process of current image frame when liquid crystal molecule, backlight module luminous light that produces under the control of described pwm control signal has reduced crosstalking of 3D from described liquid crystal molecule transmission.

Description of drawings

Below in conjunction with accompanying drawing, specific embodiments of the present invention is described in further detail, in the accompanying drawing:

Fig. 1 is the scene schematic diagram of the liquid crystal scan mode of the embodiment of the invention;

Fig. 2 is the backlight lightening sequential of the embodiment of the invention and the synchronous schematic diagram that cooperates of liquid crystal display response, 3D glasses;

Fig. 3 is the upset curve synoptic diagram of the liquid crystal response of the embodiment of the invention;

Fig. 4 is the crosstalk schematic diagram of test pattern of the 3D of the embodiment of the invention;

Fig. 5 is the schematic diagram that the liquid crystal response of the embodiment of the invention rises, changes fall time contrast;

Fig. 6 is that liquid crystal input voltage and the liquid crystal reaction (brightness change) of the embodiment of the invention concerns schematic diagram;

Fig. 7 is the cumulative effect schematic diagram of the liquid crystal of the embodiment of the invention;

Fig. 8 is the optical response time schematic diagram of the LCD of the embodiment of the invention;

Fig. 9 is the OD debugging principle schematic diagram of the embodiment of the invention;

Figure 10 is the crosstalk schematic diagram of measurement point of the GB of the embodiment of the invention;

Figure 11 is a kind of control method schematic flow sheet that improves 3D TV light transmittance of the embodiment of the invention;

Figure 12 is a kind of control device schematic diagram that improves 3D TV light transmittance of the embodiment of the invention.

Embodiment

The main concrete liquid crystal response curve of setting forth of the embodiment of the invention is on crosstalking with the impact of brightness and to its improvement measures.

Because liquid crystal scanning is carried out line by line, and remain to after having scanned when next field signal sends over always and just change simple schematic diagram such as Fig. 1.More than the hypothesis liquid crystal begins up to scan line by line from the bottom of screen, because deflecting into the angle of demonstration correct images from receiving signal, liquid crystal molecule needs the regular hour, screen take refresh rate as 120Hz is example, probably there is the time of 3-4ms this time, and the time that keeps stable has the time of general 4-5ms equally.

Fig. 1 is the scene schematic diagram of the liquid crystal scan mode of the embodiment of the invention; Wherein, subgraph A was illustrated in time of one, and the liquid crystal molecule of bottom at first reaches the image (the bottom oblique line represents) that stable state shows this.Subgraph B was illustrated in time of one, and middle liquid crystal molecule also reaches stable state, and at this moment, the liquid crystal molecule of bottom still remains on this stable state.Subgraph C was illustrated in time of one, and the liquid crystal molecule at top reaches stable state, and at this moment, the liquid crystal molecule of bottom has received the signal of next and reached stable state.

Therefore, if do not add control to backlight, get some time points, the image that we see be that a upper field picture and next field picture are seen simultaneously all the time, and 3D requires some time points, can only see one image, left eye or right eye.So we need to be controlled backlight, backlight by turn-offing in some time, make eyes can only see a complete image.

As known from the above, using in the situation of 120Hz screen at present, so-called adjusting 3D display effect, it is at all namely according to the scanning of liquid crystal molecule, get certain some time point, open or close backlight, make human eye can see the right and left eyes image of separation, and the scanning of the liquid crystal molecule here refers to liquid crystal deflecting element to stable state, shows correct image.

Fig. 2 is the backlight lightening sequential of the embodiment of the invention and the synchronous schematic diagram that cooperates of liquid crystal display response, 3D glasses; As shown in Figure 2, under the 3D, the 3D rendering signal carries out the liquid crystal addressing after arriving the liquid crystal display screen end, makes the liquid crystal molecule of respective regions be turned to certain angle, and this angle remains to a next two field picture addressing should the zone liquid crystal; The corresponding liquid crystal molecule that should be controlled at correspondence backlight is in rollover states (hold state).The sequential of opening backlight generally is with decoding 3D_vsync(3D_Vertical SYNChronization out from the 3D rendering signal, the 3D field synchronization) signal (every two field picture sends once) is benchmark, send PWM (Pulse Width Modulation, pulse width modulating technology) signaling point expose should the zone backlight, should consider the zone that delegation's LED-backlit illuminates separately simultaneously; And glasses are to open left and right sides eyeglass after receiving the Glass_vsync signal, and two two field pictures send once the Glass_vsync signal take the 3D_vsync signal as benchmark.In theory should be in certain zone the liquid crystal molecule in (zone that delegation's LED-backlit illuminates separately) open the backlight of this zone when being in Hold state (non-Hold state all is considered as non-frame image information), should be in the opening time of left eyeglass all sweep times backlight (the first row is to last column opening time backlight) of corresponding left-eye image simultaneously, should be in the opening time of right eyeglass all sweep times backlight (the first row is to last column opening time backlight) of corresponding eye image, just accomplished at last LED-backlit light sequential and liquid crystal display responds, the synchronous cooperation of 3D glasses.

In actual debug process, generally according to the lamp bar liquid crystal horizontal direction is divided into six sections, namely control 3D effect with the mode of six sections scannings backlight.Fig. 3 is the upset curve synoptic diagram of the liquid crystal response of the embodiment of the invention; In Fig. 3, ascent stage is that image is from black the reaction time to white field.Take ascent stage as example, be the time 8.3ms of a two field picture from the minimum point to the peak.Wherein, t1 is that liquid crystal has overturn and 10% overturn time of 90% to liquid crystal, is the key factor that affects the image display speed during this period of time.When the t1 time more hour, the liquid crystal upset is also fast, the performance of liquid crystal is better.T2 is the stability region after the liquid crystal upset, and luminous energy well passes through liquid crystal in this section zone, therefore, and backlight should in this section zone, opening.In like manner analyze the decline stage.

Fig. 4 is the crosstalk schematic diagram of test pattern of the 3D of the embodiment of the invention.The method of testing that present 3D crosstalks is to measure respectively the 3D pattern right and left eyes brightness of four pictures at screen center's point.Test pattern is: left white right white, left white right black, left black right white, left black right black.Respectively corresponding subgraph a), b), c), d).Table one is the right and left eyes record sheet of crosstalking.

Table one

Brightness according to record in the table one can obtain right and left eyes and crosstalk:

Crosstalking of left eye passage: CTL=(LLbw-LLbb)/(LLwb-LLbb)

Crosstalking of right eye passage: CTL=(LRwb-LRbb)/(LRbw – LRbb)

Crosstalk formula as example take left eye, molecule is that the left eyeglass lens measurement brightness (the actual black field brightness of seeing of left eye) of the black right white graph card in a left side deducts the left eyeglass lens measurement brightness (the black field brightness that left eye is seen) that right black graph card is deceived on a left side, and the meaning of its representative is that left eye is seen the brightness that is crosstalked into the black field of left eye when deceiving the field from the white field of right eye.Denominator deducts left black right left eyeglass lens measurement brightness (the black field brightness that left eye is seen) of deceiving graph card for the left eyeglass lens measurement brightness (the actual white brightness of seeing of left eye) of the black graph card in the left white right side, and the meaning of its representative is the pure white field brightness that left eye is seen.Therefore, the left eye formula of crosstalking can be drawn divided by denominator (correct brightness that left eye is seen) by molecule (the wrong brightness that left eye is seen).In like manner analyze the right eye formula of crosstalking.

Can find out from the above formula of crosstalking, if can reduce molecule numerical value, increase denominator numerical value, can effectively reduce the index of crosstalking, have good 3D effect.Can draw from a large amount of measurement results, the general brightness of black field brightness of left black right black graph card only has 0.01nit, because numerical value is minimum, the formula so left eye is crosstalked (crosstalking as example take left eye) can be approximated to be CTL=LLbw/LLwb.

Fig. 5 is the schematic diagram that the liquid crystal response of the embodiment of the invention rises, changes fall time contrast.The curve of Fig. 5 the first half is the liquid crystal response curve of the embodiment of the invention, and the curve of Fig. 5 the latter half is liquid crystal response curve in the prior art.Compare the curve of described top and the bottom as can be known, the rising edge of the liquid crystal response curve of the embodiment of the invention is steep, trailing edge is more slow, and in other words, the rise time is short, fall time is longer.When the rise time of liquid crystal, t1` was reduced to t1 since time of a field picture be (8.3ms) that fixes, so hold t2` zone time of liquid crystal will be increased to t2(Fig. 5).Under the constant prerequisite of opening time backlight, a white luminous intensity that sees through liquid crystal will increase, and is embodied in that the LLwb white brightness increases in the formula; When in like manner increased the fall time of liquid crystal, under the constant prerequisite of opening time backlight, a black luminous intensity that sees through liquid crystal can reduce, and was embodied in that the black field brightness of LLbw reduces in the formula.Like this, the left eye CTL that crosstalks will reduce.In like manner analyzing right eye crosstalks.

The design of the liquid crystal response curve of the embodiment of the invention has utilized OD(over drive) be the overvoltage drive technology.The embodiment of the invention by look-up table (look-up) function, in conjunction with corresponding optical instrument, is carried out overvoltage drive by the pressure reduction of increasing action on liquid crystal molecule by improving the response time between GTG and GTG, realizes the significantly lifting of liquid crystal response time.For explaining visually the mode of the embodiment of the invention, the example of changing into gray scale to gray scale is described in detail by Fig. 6.Fig. 6 is liquid crystal input voltage and liquid crystal reaction (brightness change) graph of a relation.Fig. 6 upper curve input A and B are input voltage; Output A and B are the liquid crystal reaction.Can find out, poor when large when input voltage, in the reaction time fast (output A), when poor hour of input voltage, react slack-off (exporting B).With the angle of liquid crystal drive, the difference of the charging voltage that the voltage on the upper display frame liquid crystal and present display frame liquid crystal will arrive, it is poor to be input voltage.Accordingly, the embodiment of the invention is accelerated the reaction speed of liquid crystal by improving described voltage difference.

The embodiment of the invention is also considered the cumulative effect of liquid crystal, and as shown in Figure 7, liquid crystal display must behind a lot of picture cycles, just can reach its target gray scale.Its liquid crystal capacitance value also can change according to this cumulative effect in the meantime, if use general type of drive, its target display brightness also can't reach at a picture cycle.So the embodiment of the invention is improved this situation with aforesaid overvoltage drive technology.Such as Fig. 8, when a higher OD signal voltage was provided, the upset of liquid crystal can speed, and simultaneously brightness can reach the target display brightness in can another picture cycle and need not through cumulative effect.The benefit of the embodiment of the invention is only to need to add an overvoltage drive function in time schedule controller, does not need liquid crystal panel change, the time that just can improve liquid crystal response.

Being the explanation adjustment method, can be that OD principle internal frame diagram framework is described referring to Fig. 9.Can find out, utilize look-up table, act on the voltage that hold in the source (source) on the liquid crystal molecule by change, change the response speed of liquid crystal molecule.Concrete debug process is as follows: the lookup table data that ideal gray level brightness is corresponding are kept among the external EEPROM; Identify the grey exponent number Gn corresponding to each pixel (pixel) of current demonstration (N frame); The grey exponent number Gn-1 corresponding with the previous frame of frame memory (memory) preservation compares, and the OD strength grade according to setting utilizes look-up table, obtains new grey exponent number, and the data that new grey exponent number is corresponding are written to Source drive (source driver) inside again; During to the N+1 frame, the data of corresponding pixel return to data corresponding to N frame again; Preserve GTG corresponding to N frame and count to the frame mnemonic; Measure the response time, as not satisfying entreat, adjust look-up table, repeat above action.Thus, can effectively reduce the rise time of liquid crystal, thus crosstalk reduction.

In sum, for the LED-backlit of determining, if can reduce the rise time of liquid crystal response curve, increase simultaneously the fall time of liquid crystal response curve, according to the formula of crosstalking, the index of crosstalking will reduce to some extent, simultaneously corresponding white brightness will increase, and black field brightness can reduce.With the 3D liquid crystal display screen of certain 32 inches single minor face light inlet modes, utilize the liquid crystal panel (same model, different batches only are to change to some extent the liquid crystal response time) of different batches, the LED-backlit of determining, test result is as shown in Table 2.Like this, 3D effect can improve significantly aspect the subjectivity and objectivity index.Specific embodiments can realize by OD debugging or additive method the change of liquid crystal response curve.

Table two

	Batch one	Batches two
			Rise time (ms)	4.08	2.75
Fall time (ms)	4.52	5.5
			3D brightness (nits)	42.2	52
3D crosstalks	3.5%	2.9%

Figure 10 is the crosstalk schematic diagram of measurement point of the GB of the embodiment of the invention.Consider method of measurement and formula that GB is crosstalked.

Among Figure 10, a equals W/30; B equals H/30.

The incoming level of measured signal utilizes 5 sections gray scales (0%, 25%, 50%, 75%, 100%), input white (grey) signal.Display measurement window simultaneously on 9 P0～P8 on the picture, the input luminance level about portrait switch and estimate.Survey map such as Fig. 6.

Measuring process following (positive side is left eye, and tossing about is right eye):

A) the left eyeglass with glasses is installed on the optical measurement device, and 3D display and glasses are carried out heat engine.

B) 9 of the display measurement side incoming level is the window (l is 0,25,50,75,100) of l%, and to locate input level be that m%(m is 0,25,50,75,100 tossing about 9) window

C) 2 dimensions are carried out in the brightness of each measurement point of P0～P8 and measure, record incoming level l%(measures side) and level m%(toss about) left eye of combination draws a portrait brightness L _{L0, l-m}～L _{L8, l-m}Measured value.At first, utilize the combination of measuring l%=0% and the m%=0% that tosses about to measure.

D) the toss about incoming level m of window switches to next value, and all m incoming levels are repeated c) operation.

E) the incoming level l that measures side window switches to next value, and all l intensity levels are repeated b)～d) operation.

F) glasses with 3D exchange to right eyeglass, to b)～e) right eye repeats the operation same with left eye, measures and record all L _{R0, l-m}～L _{R8, l-m}

Data analysis

A) eyes are crosstalked

And

Calculating, utilize the measured value of picture Pi, left and right sides unlike signal level is defeated

Fashionable brightness

Luminance difference during with same signal level input With, white

(brightness

And

With a black (minimum brightness

And

Poor ratio is shown below:

$X_{G_i,\mathrm{RtoL},m-l}=\frac{L_{L_i,l-m}-L_{L_i.l-l}}{L_{L_i,100\%-100\%}-L_{L_i,0\%-0\%}}$

$X_{G_i,\mathrm{LtoR},m-l}=\frac{L_{R_i,l-m}-L_{R_i,m-m}}{L_{R_i,100\%-100\%}-L_{R_i,0\%-0\%}}$

Wherein:

l--0％、25％、50％、75％、100％；

m--0％、25％、50％、75％、100％；

Little literal Gi is the middle GTG (Gray-to-Gray) at picture Pi place.

The eyes of b) calculating indivedual middle GTGs are crosstalked

And

The absolute average of (measured value of picture Pi) is recorded in the surveying record.

$X_{G_i,\mathrm{RtoL}}=\frac{1}{n}\left|\mathrm{\Σ}{X}_{G_i,\mathrm{RtoL},l-m}\right|$

$X_{G_i,\mathrm{LtoR}}=\frac{1}{n}\left|\mathrm{\Σ}{X}_{G_i,\mathrm{LtoR},l-m}\right|$

N is the number of removing the combination outside the l=m, is 20 herein.

With the value record of result of calculation in surveying record.

C) bring each measurement point Pi into following formula, calculate mean value, be the eyes result that crosstalks.

$X_{\mathrm{GLave}}=\frac{1}{9}\mathrm{\Σ}{X}_{G_i,\mathrm{RtoL}}$

$X_{\mathrm{GRave}}=\frac{1}{9}\mathrm{\Σ}{X}_{G_i,\mathrm{LtoR}}$

D) eyes of each measurement point Pi are crosstalked and are calculated standard deviation by following formula.

$X_{\mathrm{GL}}=\sqrt{\frac{1}{9}\mathrm{\Σ}{(X_{G_i,\mathrm{RtoL}}-X_{\mathrm{GLave}})}^2}$

$X_{\mathrm{GR}}=\sqrt{\frac{1}{9}\mathrm{\Σ}{(X_{G_i,\mathrm{LtoR}}-X_{\mathrm{GRave}})}^2}$

E) obtain 9 eyes maximum of crosstalk value as test result.

$\begin{array}{cc}{X}_{\mathrm{GL}\max }=\max \left(X_{G_i,\mathrm{RtoL}}\right)& i:0^{-}9\end{array}$

$\begin{array}{cc}{X}_{\mathrm{GR}\max }=\max \left(X_{G_i,\mathrm{LtoR}}\right)& i:0^{-}9\end{array}$

The black and white graph card calculation of crosstalk formula of crosstalking in the measure equation is generalized to the 5X5 GTG, i.e. GB the crosstalking (black is equivalent to the low GTG that GB is crosstalked, and white is equivalent to the high gray that GB is crosstalked) of middle calculating gray scale to gray scale of crosstalking.Therefore, for the analytical method of the liquid crystal response curve of the black and white graph card of crosstalking, crosstalking between the height GTG in crosstalking for GB is effectively same.

Figure 11 is a kind of control method schematic flow sheet that improves 3D TV light transmittance of the embodiment of the invention.In Figure 11, described method comprises: step 1100 receives the 3D rendering signal; Step 1102, liquid crystal indicator carries out the current image frame that field scan shows described 3D signal from a upper picture frame that shows, and extracts field sync signal from described current image frame; Step 1104 generates pwm control signal according to described field sync signal; Step 1106, when liquid crystal molecule in showing the process of current image frame because quick counter-rotating reaches rapidly when presetting the counter-rotating rate, backlight module under the control of described pwm control signal the luminous light that produces from described liquid crystal molecule transmission.

Being noted that the fast counter-rotating and reach rapidly default counter-rotating rate in showing the process of current image frame of above-mentioned liquid crystal molecule, is by reducing the rise time of liquid crystal response curve, realizing the fall time that perhaps increases the liquid crystal response curve in fact.

Figure 12 is a kind of control device schematic diagram that improves 3D TV light transmittance of the embodiment of the invention.In Figure 12, described device comprises: receiving element 1200 is used for receiving the 3D rendering signal; Display unit 1202 is used for liquid crystal indicator and carries out the current image frame that field scan shows described 3D signal from a upper picture frame that shows, and extract field sync signal from described current image frame; Generation unit 1204 is used for generating pwm control signal according to described field sync signal; Transmission units 1206 is used for reaching rapidly because reversing fast when presetting the counter-rotating rate in the process that shows current image frame when liquid crystal molecule, backlight module under the control of described pwm control signal the luminous light that produces from described liquid crystal molecule transmission.

Above-described embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is the specific embodiment of the present invention; the protection range that is not intended to limit the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1. a control method that improves 3D TV light transmittance is characterized in that, described method comprises:

Receive the 3D rendering signal;

Liquid crystal indicator carries out the current image frame that field scan shows described 3D signal from a upper picture frame that shows, and extracts field sync signal from described current image frame;

Generate pwm control signal according to described field sync signal;

When liquid crystal molecule reaches default counter-rotating rate because of counter-rotating in showing the process of current image frame, backlight module under the control of described pwm control signal the luminous light that produces from described liquid crystal molecule transmission.

2. method according to claim 1 is characterized in that, described current image frame and a upper picture frame are left-eye image frame or eye image frame.

3. method according to claim 1 is characterized in that, described current image frame is the left-eye image frame, and a upper picture frame is the eye image frame; Perhaps current image frame is the eye image frame, and a upper picture frame is the left-eye image frame.

4. a control device that improves 3D TV light transmittance is characterized in that, described device comprises:

Receiving element is used for receiving the 3D rendering signal;

Display unit is used for liquid crystal indicator and carries out the current image frame that field scan shows described 3D signal from a upper picture frame that shows, and extract field sync signal from described current image frame;

Generation unit is used for generating pwm control signal according to described field sync signal;

Transmission units is used for reaching when presetting the counter-rotating rate because of counter-rotating in the process that shows current image frame when liquid crystal molecule, backlight module under the control of described pwm control signal the luminous light that produces from described liquid crystal molecule transmission.

5. device according to claim 4 is characterized in that, described current image frame and a upper picture frame are left-eye image frame or eye image frame.

6. device according to claim 5 is characterized in that, described current image frame is the left-eye image frame, and a upper picture frame is the eye image frame; Perhaps current image frame is the eye image frame, and a upper picture frame is the left-eye image frame.

Images