CN111429852B - Control circuit and control method of liquid crystal display and display device - Google Patents
Control circuit and control method of liquid crystal display and display device Download PDFInfo
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- 239000004973 liquid crystal related substance Substances 0.000 title claims abstract description 77
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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
- G09G3/3406—Control of illumination source
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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
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Abstract
The invention relates to the technical field of display, and discloses a control circuit, a control method and a display device of a liquid crystal display, wherein the liquid crystal display comprises a liquid crystal display panel, a backlight driver and a waveform oscillator, and the control circuit comprises: the detection module receives the switch control signal and the backlight driving signal, responds to the switch control signal, detects the backlight driving signal and outputs a detection signal; the counting module is provided with a third input end for receiving the detection signal, counts according to the detection signal and outputs a counting value; and the memory is connected with the counting module and used for acquiring a voltage signal according to the counting value, wherein the waveform oscillator is connected with the memory and used for generating a periodic square wave signal with corresponding amplitude according to the voltage signal. Therefore, under the condition that the switch control signal is triggered before the backlight driving signal when the liquid crystal display is started, the influence of the waveform mutation of the driving signal on the picture dithering caused by the human vision is avoided, and the product stability is improved.
Description
Technical Field
The invention relates to the technical field of display, in particular to a control circuit, a control method and a display device of a liquid crystal display.
Background
In recent years, with the rapid development of semiconductor technology, portable electronic products and flat panel display products have been developed. Among the types of flat panel displays, Liquid Crystal Displays (LCDs) have become the mainstream of Display products due to their advantages of low voltage operation, no radiation scattering, light weight, and small size.
Generally, when the lcd is initially turned on (initial power on), power is usually supplied to the backlight module and the driving circuit of the lcd panel at the same time. However, the Low Voltage Differential Signaling (LVDS) is unstable when the lcd is just turned on, and the clock signals in the LVDS are disordered, so that the driving circuit of the lcd cannot work normally if the LVDS is directly sent to the driving board of the lcd without being processed. When the driving circuit of the lcd panel cannot work normally, the lcd panel cannot receive normal and ordered data signals, which may cause the shaking phenomenon at the initial start-up moment of the lcd, i.e. the whole screen is various color vertical bars and does not disappear, and thus image signals cannot be displayed normally.
One solution in the prior art is shown in fig. 1, a Power Integrated Chip (PIC) 110 is used to supply control signals (positive voltage signal VS + and negative voltage signal VS-) to a waveform oscillator 120 (waveform generator, which generates a periodic square wave signal Vo for controlling a source driver to output image data), and then the waveform oscillator 120 supplies a periodic square wave signal Vo (e.g. clock signal) generated for controlling the source driver to output image data to a liquid crystal display panel 130, the stable periodic square wave signal Vo stabilizes the performance of the display, the waveform of the generated periodic square wave signal Vo is shown in fig. 2, but since the waveform of the periodic square wave signal Vo generated by the waveform oscillator 120 cannot be flexibly changed, if the switching control signal of the liquid crystal display panel is started before the backlight driving signal BL _ EN of the backlight module VIN during Power-on, obvious visual jitter is generated, so the current scheme cannot avoid the visual jitter caused when the switch control signal VIN of the liquid crystal display panel is started before the backlight driving signal BL _ EN of the backlight module when the backlight module is started.
Disclosure of Invention
In order to solve the above technical problems, the present invention provides a control circuit, a control method and a display device for a liquid crystal display, which can improve the influence of the waveform mutation of a driving signal on the visual sensation of human eyes when the liquid crystal display is turned on in a backlight off state, and improve the stability of the product.
In one aspect, the present invention provides a control circuit of a liquid crystal display, where the liquid crystal display includes a liquid crystal display panel, a backlight driver, and a waveform oscillator electrically connected to the liquid crystal display panel, the control circuit is connected to the waveform oscillator and the backlight driver, respectively, and the control circuit includes:
the detection module is provided with a first input end for receiving a switch control signal and a second input end for receiving a backlight driving signal, and the detection module responds to the received switch control signal, detects the backlight driving signal and outputs a detection signal;
the counting module is provided with a third input end for receiving the detection signal, counts according to the detection signal and outputs a counting value;
a memory connected with the output end of the counting module and used for obtaining a voltage signal according to the counting value,
the waveform oscillator is connected with the output end of the memory and generates periodic square wave signals with corresponding amplitudes according to the voltage signals.
Preferably, the memory stores a lookup table corresponding to the count value, the lookup table can select a voltage signal corresponding to a set amplitude value to be output according to the count value, and the voltage amplitude value of the periodic square wave signal follows the amplitude value of the voltage signal.
Preferably, the counting module is a counter.
Preferably, when detecting that the switch control signal is at a high level and the backlight driving signal is not at the high level, the control circuit sequentially outputs a plurality of voltage signals with gradually increasing amplitudes; when the switch control signal is detected to be at a high level and the backlight driving signal is detected to be at a high level, the memory outputs a voltage signal at a constant high level.
Preferably, when detecting that the backlight driving signal is at a low level and the switch control signal is at a high level, the control circuit sequentially outputs a plurality of voltage signals with gradually decreasing amplitudes; when the backlight driving signal is detected to be at a low level and the switch control signal is at a low level, the memory outputs a voltage signal at a constant low level.
In another aspect, the present invention provides a method for controlling a liquid crystal display, the liquid crystal display including a liquid crystal display panel, a backlight driver, and a waveform oscillator electrically connected to the liquid crystal display panel, wherein the liquid crystal display is controlled using a control circuit of the liquid crystal display as described above, the method comprising:
detecting whether the backlight driving signal is at a high level in response to the received switch control signal being at the high level;
if not, starting forward counting, and outputting a count value;
selecting a voltage signal corresponding to a set amplitude value according to the count value and outputting the voltage signal;
detecting that the backlight driving signal is at a high level, and outputting the constant voltage signal;
and the waveform oscillator generates periodic square wave signals with corresponding amplitudes according to the voltage signals.
Preferably, the control method further includes:
detecting whether the switch control signal is at a high level in response to the received backlight driving signal being at a low level;
if so, starting to count reversely, and outputting a count value;
selecting a voltage signal corresponding to a set amplitude value according to the count value and outputting the voltage signal;
detecting that the switch control signal is at a low level, and outputting the constant voltage signal;
and the waveform oscillator generates periodic square wave signals with corresponding amplitudes according to the voltage signals.
Preferably, in the detecting that the backlight driving signal is at a high level and outputting the constant voltage signal, the voltage signal is a high level signal.
Preferably, in the step of detecting that the switch control signal is at a low level and outputting the constant voltage signal, the voltage signal is a low level signal or a ground level signal.
In another aspect, the present invention provides a display device, including:
the liquid crystal display comprises a liquid crystal display panel, a backlight driver and a waveform oscillator electrically connected with the liquid crystal display panel;
as described in the control circuit of the liquid crystal display device in the above,
the control circuit is connected with the waveform oscillator and controls the waveform oscillator to generate periodic square wave signals with corresponding amplitudes.
The invention has the beneficial effects that: the invention provides a control circuit, a control method and a display device of a liquid crystal display, wherein the control circuit detects a backlight driving signal by responding to a received switch control signal, outputs a detection signal, counts according to the detection signal and outputs a counting value, and then outputs a voltage signal with adjustable amplitude according to the counting value, wherein the voltage signal is used for limiting the amplitude of a periodic square wave signal output by a waveform oscillator, so that the amplitude of the periodic square wave signal received by a liquid crystal display panel is adjustable under the condition that the switch control signal is triggered before the backlight driving signal when the display is started, thereby improving the influence of the waveform mutation of the driving signal on the picture jitter of human eyes under the condition that the switch control signal is triggered before the backlight driving signal when the display is started, and improving the product stability.
Preferably, the detection module starts to detect the backlight driving signal by responding to the received switch control signal being at a high level, starts to count in a forward direction and outputs a count value by the counting module when the backlight driving signal is at a low level or a rising edge is met, the memory selects a voltage signal corresponding to a set amplitude value to output according to the count value, the control circuit outputs a voltage signal of a constant high level until the backlight driving signal is detected to be at the high level, and the waveform oscillator generates a periodic square wave signal of a fixed amplitude value according to the voltage signal.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a control circuit of a liquid crystal display in the prior art;
FIG. 2 is a schematic diagram showing waveforms of signals when the LCD shown in FIG. 1 is turned on and off;
FIG. 3 is a schematic diagram of a control circuit of a liquid crystal display according to an embodiment of the present invention;
fig. 4 is a flowchart illustrating a control method for turning on a liquid crystal display according to an embodiment of the invention;
fig. 5 is a flowchart illustrating a control method for turning off a liquid crystal display according to an embodiment of the present invention;
fig. 6 is a schematic diagram showing signal waveforms when the lcd shown in fig. 3 is turned on and off.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The present invention will be described in detail below with reference to the accompanying drawings.
Fig. 3 is a schematic structural diagram of a control circuit of a liquid crystal display according to an embodiment of the present invention.
Referring to fig. 3, an embodiment of the present invention provides a control circuit 210 of a liquid crystal display, the liquid crystal display includes a liquid crystal display panel 230, a backlight driver 240, and a waveform oscillator 220 electrically connected to the liquid crystal display panel 230, the control circuit 210 is respectively connected to the waveform oscillator 220 and the backlight driver 240, the control circuit 210 includes but is not limited to: a detection module 201, a counting module 202 and a memory 203. The detection module 201 has a first input end for receiving a switch control signal VIN and a second input end for receiving a backlight driving signal BL _ EN, when the computer is powered on, the detection module 201 responds to the received high-level switch control signal VIN to detect the backlight driving signal BL _ EN and output a detection signal, the counting module 202 has a third input end for receiving the detection signal, the counting module 202 counts according to the detection signal and outputs a count value, the memory 203 is connected with an output end of the counting module 202, and selects a voltage signal VS corresponding to a set amplitude according to the count value. The waveform oscillator 220 is connected to the output end of the memory 203, and generates a periodic square wave signal Vo with a corresponding amplitude according to the received positive voltage signal VS + and the negative voltage signal VS-, wherein the amplitude of the voltage of the periodic square wave signal Vo follows the amplitude of the voltage signal VS.
In a preferred embodiment, the memory 203 stores a look-up table corresponding to the count values, the look-up table (LUT) stores a plurality of count values and a plurality of voltage signals VS with different amplitudes corresponding to the plurality of count values, and the voltage signals corresponding to the set amplitudes can be selected according to the count values for output.
In a preferred embodiment, the counting module 202 is a counter.
In a preferred embodiment, the detecting module 201 may be, but is not limited to, a voltage detecting circuit, and is configured to detect the switch control signal VIN and the backlight driving signal BL _ EN, start to detect the backlight driving signal BL _ EN when detecting that the switch control signal VIN is at a high level, and output a detection signal to the counting module 202 when detecting that the backlight driving signal BL _ EN is at a low level or a rising edge, so that the counting module 202 starts to count in a forward direction.
In this embodiment, when the lcd is turned on, the control circuit 210 first detects the switch control signal VIN, and detects the backlight driving signal BL _ EN in response to that the received switch control signal VIN is at a high level, and when a rising edge (or a high level) of the backlight driving signal is not detected, that is, the switch control signal VIN is started before the backlight driving signal BL _ EN, at this time, the detection module 201 outputs a detection signal to the counting module 202, the counting module 202 starts counting in a forward direction, for example, from 1 to 2 to 3, the counting module 202 outputs count values to the memory 203, each count value corresponds to a voltage signal VS with an amplitude, the count value gradually increases, and the amplitude of the corresponding voltage signal VS also gradually increases. Then, the lookup table in the memory 203 selects a voltage signal VS corresponding to a set amplitude to output to the waveform oscillator 220, wherein the absolute values of the amplitudes of the output positive voltage signal VS + and the negative voltage signal VS-are equal, the amplitude of the generated positive voltage signal VS + is gradually increased from small to large along with the positive increase of the count value, the waveform oscillator 220 generates a periodic square wave signal Vo with a corresponding amplitude according to the voltage signal VS, and the voltage signal VS is used for limiting the voltage amplitude of the periodic square wave signal Vo output by the waveform oscillator 220, so that the voltage amplitude of the periodic square wave signal Vo is gradually increased along with the amplitude of the voltage signal VS. Therefore, the amplitude of the periodic square wave signal Vo and the value of the voltage signal VS change synchronously and gradually increase from small to large until the high level of the backlight driving signal BL _ EN is detected, the counting is stopped, the voltage signal VS is output as a set threshold, that is, a constant high level voltage signal VS is output through a lookup table in the memory 203, and the waveform oscillator 220 generates the periodic square wave signal Vo with a constant amplitude according to the constant high level voltage signal VS, wherein the set threshold and the detection frequency of the counter can be set or modified according to the working requirements of the actual circuit, which is not limited herein.
Based on the embodiment, under the condition that the switch control signal is triggered before the backlight driving signal when the liquid crystal display is started, the influence of the waveform mutation of the driving signal on the picture shaking caused by the vision of human eyes is avoided, the product stability is improved, and meanwhile, the user experience is improved.
In another embodiment of this embodiment, when the lcd is turned off, the control circuit 210 first detects whether the backlight driving signal BL _ EN of the backlight driver 240 is at a low level, detects the switch control signal VIN when detecting that the backlight driving signal BL _ EN is at a low level or a falling edge, and when not detecting the falling edge (or the low level) of the switch control signal VIN, it indicates that the switch control signal VIN is turned off after the backlight driving signal BL _ EN, at this time, the detection module 201 outputs the detection signal to the counting module 202, the counting module 202 starts to count in reverse, for example, from 3 to 2 to 1, where the gradually decreased count value corresponds to the gradually increased count value exactly one to one during the turn-on process. The memory 203 outputs voltage signals VS having different amplitudes according to each count value, and the amplitudes of the output voltage signals VS are sequentially decreased in response to the count value being gradually decreased. The look-up table in the memory 203 then selects the voltage signal VS corresponding to the set amplitude to be output to the waveform oscillator 220, wherein, the absolute value of the amplitude of the output positive voltage signal VS + is equal to that of the negative voltage signal VS-, the amplitude of the generated positive voltage signal VS + is gradually decreased from large to small with the inverse decrease of the counting value, the waveform oscillator 220 generates the periodic square wave signal Vo with the same amplitude according to the voltage signal VS, so that the amplitude of the periodic square wave signal Vo is synchronously changed with the value of the voltage signal VS and is gradually decreased from large to small until the counting is stopped when the low level of the switch control signal VIN is detected, the voltage signal VS is output with the set threshold value, i.e. a constant low level voltage signal VS is output via a look-up table in the memory 203, and the waveform oscillator 220 generates a periodic square wave signal Vo of constant amplitude from this constant low level voltage signal VS. Further, the constant low level voltage signal VS is a low level signal or a zero level signal connected to the ground.
Based on the above embodiment, when the liquid crystal display is turned off, the backlight driving signal is triggered before the on-off control signal, so that the influence of image ghost on the vision of human eyes due to the residual image of part of image data or noise signals before turning off is avoided, and the user experience is improved while the product stability is improved.
In a preferred embodiment, the control circuit 210 may be integrated on the same chip. The chip is, for example, a Power Integrated Chip (PIC), which can effectively reduce the circuit wiring space and save the area.
Fig. 4 is a schematic flow chart illustrating a control method for turning on a liquid crystal display according to an embodiment of the present invention, fig. 5 is a schematic flow chart illustrating a control method for turning off a liquid crystal display according to an embodiment of the present invention, and fig. 6 is a schematic signal waveform illustrating the liquid crystal display shown in fig. 3 when turning on and turning off the liquid crystal display.
Further, the present embodiment also provides a method for controlling a liquid crystal display, where the liquid crystal display includes a liquid crystal display panel, a backlight driver, and a waveform oscillator electrically connected to the liquid crystal display panel. Referring to fig. 4 and 6, at the time of booting, the control method includes:
step S110: and (6) powering up.
Step S120: the switch control signal VIN is detected to be high.
In step S120, when the lcd is powered on, it is detected whether the switch control signal VIN is at a high level, and when the switch control signal VIN is detected as at the high level, the received backlight driving signal BL _ EN is detected, and step S130 is executed.
Step S130: it is detected whether the backlight driving signal BL _ EN is at a high level.
In step S130, if it is detected that the backlight driving signal BL _ EN is at a high level, it represents that the backlight driving signal is simultaneously activated with the switch control signal VIN, and step S170 is executed; if the backlight driving signal BL _ EN is detected to be at a low level, which represents that the backlight driving signal BL _ EN is later than the on time of the switch control signal VIN, step S140 is executed.
Step S140: the counting module 202 counts.
In step S140, the counting module 202 detects the backlight driving signal BL _ EN according to the detection signal, starts to count in the forward direction when the rising edge (or high level) is not detected, outputs count values one by one, and then performs step S150.
Step S150: the corresponding voltage signal VS is selected in a look-up table in the memory 203.
In step S150, a voltage signal VS corresponding to a set amplitude is selected from a look-up table in the memory 203 according to the count value output one by one.
Step S160: a periodic square wave signal Vo is generated.
In step S160, a plurality of voltage signals VS with sequentially increasing voltage amplitudes are sequentially output to the waveform oscillator 220 according to the selection result of step S150, wherein the voltage signals VS include a positive voltage signal VS + and a negative voltage signal VS-, the absolute values of the amplitudes of the output positive voltage signal VS + and negative voltage signal VS-are equal, the value of the generated positive voltage signal VS + is gradually increased from small to large as the count value is increased in the positive direction, the waveform oscillator 220 generates a periodic square wave signal Vo with corresponding amplitude according to the voltage signal VS, so that the amplitude of the periodic square wave signal Vo is synchronously changed with the amplitude of the voltage signal VS and is gradually increased from small to large until the high level of the backlight driving signal BL _ EN is detected, and step S170 is executed again.
Step S170: a periodic square wave signal Vo of constant amplitude is generated.
In step S170, when it is detected that the switching control signal VIN is at a high level and the backlight driving signal BL _ EN reaches the high level, the counting is stopped, the voltage signal VS is output as a set threshold, i.e., a constant high-level voltage signal VS is output through a lookup table in a memory, and the waveform oscillator generates a periodic square wave signal Vo with a constant amplitude according to the constant high-level voltage signal VS, wherein the set threshold and the detection frequency of the counter can be set or modified according to the working requirements of the actual circuit.
Based on the embodiment, under the condition that the switch control signal is triggered before the backlight driving signal when the liquid crystal display is started, the influence of the waveform mutation of the driving signal on the picture shaking caused by the vision of human eyes is avoided, the product stability is improved, and meanwhile, the user experience is improved.
In a preferred embodiment, referring to fig. 5 and 6, the control method further includes, at the time of shutdown:
step S210: the backlight driving signal BL _ EN is detected to be low level.
In step S210, when the power is turned off, first, whether the backlight driving signal BL _ EN of the backlight driver is at a low level is detected, and when the backlight driving signal BL _ EN is detected to be at the low level, step S220 is executed; if the backlight driving signal BL _ EN of the backlight driver is still detected to be at the high level, indicating that the liquid crystal display has not entered the shutdown process, this step is executed in a loop until the backlight driving signal BL _ EN is detected to be at the low level, and step S220 is executed.
Step S220: it is detected whether the switch control signal VIN is high.
In step S220, it starts to detect whether the switch control signal VIN is at a high level, and if it is detected that the switch control signal VIN is at a low level, it indicates that the switch control signal VIN and the backlight driving signal BL _ EN are synchronously turned off, and step S260 is directly executed; if the switch control signal VIN is detected to be at a high level, it indicates that the backlight driving is prior to the turning off of the liquid crystal display panel, and then step S230 is executed.
Step S230: the counting module 202 counts.
In step S230, the counting module 202 detects the backlight driving signal BL _ EN according to the detection signal, starts to count in reverse when the falling edge (or low level) thereof is not detected, outputs a count value, and then performs step S240.
Step S240: the corresponding voltage signal VS is selected in a look-up table in the memory 203.
In step S240, the voltage signal VS corresponding to the set amplitude is selected according to the look-up table in the count value corresponding memory 203, and step S250 is executed.
Step S250: a periodic square wave signal Vo is generated.
In step S250, a voltage signal VS is output according to the selection result of step S240, wherein the absolute values of the output positive voltage signal VS + and the output negative voltage signal VS-are equal, the value of the generated positive voltage signal VS + is gradually decreased from large to small with the inverse decrease of the count value, the voltage signal VS generates a periodic square wave signal Vo with a corresponding amplitude by the waveform oscillator 220, so that the amplitude of the periodic square wave signal Vo is changed synchronously with the value of the voltage signal VS and is also gradually decreased from large to small until the low level of the switching control signal VIN is detected, and step 260 is executed.
Step S260: a periodic square wave signal Vo of constant amplitude is generated.
In step S260, when it is detected that the backlight driving signal BL _ EN is at a low level and the switch control signal VIN reaches a low level, the counting is stopped, the voltage signal VS is output as a set threshold, i.e., a constant low-level voltage signal VS is output through a lookup table in the memory, and the waveform oscillator generates a periodic square wave signal Vo with a constant amplitude according to the constant low-level voltage signal VS.
Based on the above embodiment, when the liquid crystal display is turned off, the backlight driving signal is triggered before the on-off control signal, so that the influence of image ghost on the vision of human eyes due to the residual image of part of image data or noise signals before turning off is avoided, and the user experience is improved while the product stability is improved.
In this embodiment, referring to fig. 6, the waveform of the periodic square wave signal Vo generated in the control method shown in fig. 4 is changed from the time t1 to the time t2, wherein as the count value is increased in the positive direction, the amplitude of the periodic square wave signal Vo is also increased gradually from small to large along with the value of the positive voltage signal VS +, for example, the amplitude is increased from VS1+ to VS2+ and then increased to VS3+, and the amplitude of the constant high-level positive voltage signal VS3+ is the amplitude of the periodic square wave signal Vo required when the liquid crystal display panel normally operates (i.e., a set threshold), and the change of the correspondingly generated negative voltage signal VS-is the same as that of the periodic square wave signal Vo, which is not described herein again. Therefore, the amplitude of the periodic square wave signal Vo when the liquid crystal display panel is started up under the backlight driving off state is gradually increased from zero to the required amplitude.
From time t2 to time t3, the liquid crystal display is in a normal operating state, and the control circuit of the liquid crystal display in this embodiment provides a periodic square wave signal Vo of constant amplitude.
The periodic square wave signal Vo generated in the control method shown in fig. 5 changes from the time t3 to the time t4, wherein, as the count value is inversely decreased, the amplitude of the periodic square wave signal Vo is also gradually decreased from large to small along with the value of the positive voltage signal VS +, for example, decreased from VS3+ to VS2+ and then decreased to VS1+, and finally decreased to a zero level signal, while the voltage signal VS with a constant low level is a zero level signal that is grounded, and the change of the correspondingly generated negative voltage signal VS-is the same as that of the zero level signal, which is not described herein again. Therefore, the amplitude of the periodic square wave signal Vo gradually changes to zero when the liquid crystal display panel is turned off under the backlight driving off state.
Further, the present invention also provides a display device, comprising:
the liquid crystal display comprises a liquid crystal display panel, a backlight driver and a waveform oscillator electrically connected with the liquid crystal display panel;
as in the control circuit of the liquid crystal display in the above,
the control circuit is connected with the waveform oscillator, and controls the waveform oscillator to generate periodic square wave signals with corresponding amplitudes.
In summary, according to the control circuit, the control method and the display device of the liquid crystal display provided by the invention, the backlight driving signal is started to be detected by responding to the fact that the received switch control signal is greater than or equal to the first preset threshold value, the counting module starts to count in the forward direction and output the count value when the backlight driving signal is smaller than the second preset threshold value, the voltage signal corresponding to the set amplitude value is selected according to the count value to be output, the control circuit outputs the voltage signal with the constant high level until the backlight driving signal is detected to be equal to or greater than the second preset threshold value, and the waveform oscillator generates the periodic square wave signal with the corresponding amplitude value according to the voltage signal. On one hand, the influence of the waveform mutation of the driving signal on the picture dithering caused by the human eye vision can be avoided under the condition that the on-off control signal is triggered prior to the backlight driving signal when the liquid crystal display is started, on the other hand, the influence of the picture ghost image caused by the partial image picture data or the noise signal before the shutdown can be avoided under the condition that the backlight driving signal is triggered prior to the on-off control signal when the liquid crystal display is shut down, the product stability is improved, and meanwhile, the user experience is also improved.
It should be noted that in the description of the present invention, it is to be understood that the terms "upper", "lower", "inner", and the like, indicate orientation or positional relationship, are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referenced components or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
Further, in this document, the contained terms "include", "contain" or any other variation thereof are intended to cover a non-exclusive inclusion, so that a process, a method, an article or an apparatus including a series of elements includes not only those elements but also other elements not explicitly listed or inherent to such process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.
Claims (10)
1. A control circuit for a liquid crystal display, the liquid crystal display comprising a liquid crystal display panel, a backlight driver, and a waveform oscillator electrically connected to the liquid crystal display panel, the control circuit being connected to the waveform oscillator and the backlight driver, respectively, the control circuit comprising:
the detection module is provided with a first input end for receiving a switch control signal and a second input end for receiving a backlight driving signal, and the detection module responds to the received switch control signal, detects the backlight driving signal and outputs a detection signal;
the counting module is provided with a third input end for receiving the detection signal, counts according to the detection signal and outputs a counting value;
a memory connected with the output end of the counting module and used for obtaining a voltage signal according to the counting value,
the waveform oscillator is connected with the output end of the memory and generates periodic square wave signals with corresponding amplitudes according to the voltage signals.
2. The control circuit of claim 1, wherein the memory stores a look-up table corresponding to the count value, the look-up table being capable of selecting a voltage signal output corresponding to a set amplitude according to the count value, the voltage amplitude of the periodic square wave signal following the amplitude of the voltage signal.
3. The control circuit of claim 1, wherein the counting module is a counter.
4. The control circuit of claim 1, wherein the control circuit sequentially outputs a plurality of voltage signals with gradually increasing amplitudes when detecting that the switch control signal is at a high level and the backlight driving signal is not at a high level; when detecting that the switch control signal is at a high level and the backlight driving signal is at a high level, the memory outputs a voltage signal of a constant high level.
5. The control circuit of claim 1, wherein the control circuit sequentially outputs a plurality of voltage signals with gradually decreasing amplitudes when detecting that the backlight driving signal is at a low level and the switch control signal is at a high level; when detecting that the backlight driving signal is at a low level and the switch control signal is at a low level, the memory outputs a voltage signal of a constant low level.
6. A control method of a liquid crystal display including a liquid crystal display panel, a backlight driver, and a waveform oscillator electrically connected to the liquid crystal display panel, wherein the liquid crystal display is controlled using a control circuit of the liquid crystal display according to any one of claims 1 to 5, the control method comprising:
detecting whether the backlight driving signal is at a high level in response to the received switch control signal being at the high level;
if not, starting forward counting, and outputting a count value;
selecting a voltage signal corresponding to a set amplitude value according to the count value and outputting the voltage signal;
detecting that the backlight driving signal is at a high level, and outputting the constant voltage signal;
and the waveform oscillator generates periodic square wave signals with corresponding amplitudes according to the voltage signals.
7. The control method according to claim 6, characterized by further comprising:
detecting whether the switch control signal is at a high level in response to the received backlight driving signal being at a low level;
if so, starting to count reversely, and outputting a count value;
selecting a voltage signal corresponding to a set amplitude value according to the count value and outputting the voltage signal;
detecting that the switch control signal is at a low level, and outputting the constant voltage signal;
and the waveform oscillator generates periodic square wave signals with corresponding amplitudes according to the voltage signals.
8. The control method according to claim 6, wherein the voltage signal is a high level signal in the step of detecting that the backlight driving signal is a high level and outputting the constant voltage signal.
9. The control method according to claim 7, wherein the voltage signal is a low level signal or a ground level signal in the detecting that the switch control signal is a low level and outputting the constant voltage signal.
10. A display device, comprising:
the liquid crystal display comprises a liquid crystal display panel, a backlight driver and a waveform oscillator electrically connected with the liquid crystal display panel;
further comprising a control circuit for the liquid crystal display according to any one of claims 1 to 5,
the control circuit is connected with the waveform oscillator and controls the waveform oscillator to generate periodic square wave signals with corresponding amplitudes.
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