Liquid crystal display systems
Technical field
The present invention relates to a kind of liquid crystal display systems, particularly a kind of liquid crystal display systems of taking precautions against the ripples line.
Background technology
LCD (LCD) is to utilize the variation that is added in electric field intensity on the liquid crystal molecule, and the power that changes the orientation control printing opacity of liquid crystal molecule is come display image.At present, LCD since its have in light weight, volume is little, the thin thickness characteristics, be used in widely in the terminal presentation facility of various sizes.In general, a complete display panels as shown in Figure 1, by drives module 11, backlight module 12, the layer of liquid crystal molecule 15 of filling in polaroid 13, TFT (thin film transistor (TFT)) infrabasal plate 14, the box formed by two substrates down, CF (color filter) upper substrate 16 and on formation such as polaroid 17.Backlight module plays the effect that backlight is provided in display panels, be light emitting source with CCFL (cold-cathode fluorescence lamp) fluorescent tube usually.
When display panels is used as the video display terminal (VDT), because the TV modulation signal TSC-system that the U.S. and Japan and other countries are used, field frequency is 60HZ, and the TV modulation signal PAL-system that China and most of European countries use, field frequency is 50HZ, so when display panels when country variant uses, can receive two kinds of different field frequencies, be respectively two kinds of 60HZ and 50HZ.In addition, owing to use the interleave technology at present on display panels, the actual frame frequency that uses of display panels can be exported as the frequency-doubled signal of radix with 50HZ or 60HZ usually.Because display panels uses progressive scanning technology usually; (Horizontal Frequency) is different with frame frequency according to resolution for its horizontal frequency; usually can be between several KHZ and hundreds of KHZ; and the CCFL fluorescent tube is the high-voltage alternating driven for emitting lights; when the horizontal frequency that shows when display panels is close with the a-c cycle of CCFL lamp works; the vision of human eye can be commonly called as the ripples line because the cause that both frequencies relate to is mutually seen the band scintillation easily in display frame.
Summary of the invention
The technical matters that the present invention solves is taken precautions against owing to field frequency changes the liquid crystal display systems that the ripples line occurs for providing a kind of.
For addressing the above problem, the invention provides a kind of liquid crystal display systems, comprise drives module, backlight module, described drives module comprises time schedule controller, described drives module comprises the lamp works frequency control unit, the lamp works frequency of described backlight module is controlled, and is controlled by described lamp works frequency control unit, and described lamp works frequency control unit is controlled by described time schedule controller.
Described lamp works frequency control unit is a kind of step-by-step counting comparison means, comprises one road pulse input signal, counter, default fixed frequency, one tunnel output control signal at least.
Described lamp works frequency control unit presets fixed frequency, and the STV signal of input NTSC or pal mode is then exported corresponding standard signal and given described backlight module.
Described lamp works frequency control unit presets fixed frequency, when the STH signal of importing is higher or lower than default fixed frequency, exports control signal corresponding and gives described backlight module.
When the present invention uses different horizontal frequencies to show at display panels, owing to can correspondingly adjust the lamp works frequency in the backlight module, thereby reach the purpose of taking precautions against the ripples line.Particularly for LCD TV, adopt in the time of can avoiding watching TV programme behind the liquid crystal display systems of the present invention in the area of TSC-system or PAL-system, water ripple phenomenon appears owing to the input field frequency changes.
Description of drawings
Fig. 1 is the structure of liquid crystal display panel synoptic diagram of prior art;
Fig. 2 is that the display panels of prior art drives synoptic diagram;
Fig. 3 is for using liquid crystal panel structure synoptic diagram of the present invention;
Fig. 4 realizes block diagram for using system of the present invention;
Fig. 5 is the system chart of the embodiment of the invention one;
Fig. 6 is the system chart of the embodiment of the invention two.
Among the figure:
11 drives modules; 12 backlight modules; 13 times polaroids;
The 14TFT infrabasal plate; 15 layer of liquid crystal molecule; The 16CF upper substrate;
Polaroid on 17; 21 LCDs; 22 time schedule controllers;
23 source drive IC; 24 gate driving IC; 31 lamp works frequency control units;
Embodiment
The present invention will be further described below in conjunction with accompanying drawing and exemplary embodiments.
Embodiment one
As the video display terminal (VDT), also unrestricted as the resolution of the display panels of using present embodiment one, but for present embodiment is described better, the resolution of getting 1400*900 describes.With reference to Fig. 5, time schedule controller 22 shows for the display panels of controlling this 1400*900 resolution, can comprise the STV signal usually in the signal of sending for source IC 23 and gate driving IC24, and wherein, STV is that grid begins pulse signal.At this moment, can carry out the frame frequency counting to the STV signal, judge controller control signal output by standard then as the frame frequency counter in the lamp works frequency control unit 31.In the present embodiment, standard judges that the mode of operation of controller is as follows, the frame frequency that calculates when the frame frequency counter is greater than 55HZ, can think that display panels exporting the image of TSC-system, output control signal 1 is given backlight module, and at this moment the CCFL fluorescent tube in the backlight module uses the frequency of operation that can not occur the ripples line under TSC-system; The frame frequency that calculates when the frame frequency counter is less than 55HZ, can think that display panels exporting the image of PAL-system, and output control signal 2 is given backlight module, and at this moment the CCFL fluorescent tube in the backlight module uses the frequency of operation that can not occur the ripples line under PAL-system.The possible range of lamp works frequency is as follows, exporting the image of TSC-system when display panels, frame frequency is 60HZ, because its resolution is 1400*900, when it uses the demonstration of VESA (VESA) standard, its horizontal frequency is generally 56KHZ, and the frequency of operation that at this moment need control fluorescent tube is avoided the working range of 50K~62KHZ; Exporting the image of PAL-system when display panels, frame frequency is 50HZ, because its resolution is 1400*900, when it uses the demonstration of VESA standard, its horizontal frequency is generally 46KHZ, and the frequency of operation that at this moment need control fluorescent tube is avoided the working range of 40K~52KHZ.From the above mentioned, present embodiment is as a special example, when having of CCFL fluorescent tube just has better practicability when the frequency optimum traffic scope is 40K~62KHZ.In the present embodiment, though enumerated the operating frequency range of some recommendations, the frequency optimum traffic reference quantity when specifically using can be revised by concrete CCFL fluorescent tube characteristic.
Embodiment two
Display panels is as display terminal, when using different purposes, and the level that provides along with time schedule controller and the change of vertical control signal, the horizontal frequency that display panels shows may change in a big way.The display panels that with resolution is 1400*900 equally is an example, when frame frequency is carried out the change of 50~120HZ, the horizontal frequency that this display panels shows can change between 46K~116KHZ, at this moment, when the frequency optimum traffic scope of CCFL fluorescent tube drops on this interval, then may the ripples line appear for certain frame frequency.At this situation, as shown in Figure 6, time schedule controller output STH signal is given the lamp works frequency controller, and STH is horizontal initial pulse signal.As the horizontal frequency counter in the lamp works frequency control unit 31 the STH signal-count is calculated the horizontal frequency of display panels, export by fixed frequency comparer control signal then.In the present embodiment, when the frequency optimum traffic scope of CCFL fluorescent tube is 60K~80KHZ, getting 70KHZ compares as fixed frequency and horizontal frequency, when horizontal frequency during greater than 70KHZ, output control signal 1 is given backlight module, and the CCFL lamp works frequency in the control backlight is between 60K~64KHZ; When horizontal frequency during less than 70KHZ, output control signal 2 is given backlight module, and the CCFL lamp works frequency in the control backlight is between 76K~80KHZ.In the present embodiment, though enumerated the operating frequency range of some recommendations, the frequency optimum traffic reference quantity when specifically using can be revised by concrete CCFL fluorescent tube characteristic.
Therefore, when the present invention uses different horizontal frequencies to show at display panels, owing to can correspondingly adjust the lamp works frequency in the backlight module, thereby can reach the purpose of taking precautions against the ripples line.
Though the present invention discloses as above with preferred embodiment; right its is not in order to qualification the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; when can doing a little modification and perfect, so protection scope of the present invention is when with being as the criterion that claims were defined.