CN106373536B - Liquid crystal capacitance driving circuit and method - Google Patents
Liquid crystal capacitance driving circuit and method Download PDFInfo
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- CN106373536B CN106373536B CN201610811636.3A CN201610811636A CN106373536B CN 106373536 B CN106373536 B CN 106373536B CN 201610811636 A CN201610811636 A CN 201610811636A CN 106373536 B CN106373536 B CN 106373536B
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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
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3696—Generation of voltages supplied to electrode drivers
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Abstract
A kind of liquid crystal capacitance driving circuit, is suitable for one liquid crystal capacitance of electrical connection, which includes a transmission unit, a converting unit, an output unit and a judging unit；The transmission unit receives the pixel data of multiple numbers and transmits in order；The converting unit receives each pixel data and generates a corresponding driving voltage；The output unit includes an operational amplifier, which has a prime control group, a first switch group and a second switch group；Judging unit generates a comparison result according to two pixel datas that the transmission unit successively transmits, the prime control group controls the first switch group and exports first electric current to the liquid crystal capacitance, and controls whether the second switch group exports second electric current to the liquid crystal capacitance according to comparison result.
Description
Technical field
The invention relates to a kind of driving circuits, particularly relate to a kind of liquid crystal capacitance driving electricity for LCD screen
Road.
The prior art
The picture of LCD screen is made of multiple pixels (pixel) arranged in arrays, the quantity definition of these pixels
The resolution ratio of the LCD screen, for example, resolution ratio 1920x1080, that is, Full HD (Full High
It is Definition, also referred to as full HD) LCD screen of specification, the quantity of its pixel is about 2,000,000, in another example
Resolution ratio is 3840x2160, that is, the liquid crystal of Ultra HD (Ultra High Definition, also referred to as ultra high-definition) specification
Screen, the quantity of its pixel is about 8,200,000, and wherein each pixel requires to be driven by driving circuit
It is dynamic, and drive each time all and need consumption electric energy, that is to say, that the resolution ratio of LCD screen is higher, represents driving all pixels institute
The electric energy needed is also bigger.
Refering to fig. 1, the liquid crystal capacitance driving circuit 9 of the prior art is suitable for being electrically connected the liquid crystal that a control pixel is shown
Capacitor Cs, the liquid crystal capacitance driving circuit 9 include 91, digital analog converters 92 of a latch group and an operation
Amplifier 93.The latch group 91 receives a digital pixel data (pixel data) and is sent to the digital simulation
The pixel data is converted to a corresponding analog drive voltage and is transmitted by converter 92, the digital analog converter 92
To the operational amplifier 93, which drives liquid crystal capacitance Cs again with the analog drive voltage, to provide electric current
To liquid crystal capacitance Cs charge or discharge, the pixel energy is made to show correct brightness according to the voltage that liquid crystal capacitance Cs is provided.
In order to cooperate refering to Fig. 2 and Fig. 3, the inside of existing operational amplifier 93 has to liquid crystal capacitance Cs charge/discharge
One AB class (Class AB) amplifier, the class ab ammplifier have multiple (indicate with M=8, the multiple crystalline substances being connected in parallel to each other of M table
The quantity of body pipe, M are natural number, M >=1) P-type transistor and multiple (being indicated with M=4) N-type transistors.For example, In
When first time t1 shown in Fig. 3, according to some pixel data, if the output voltage Vout at the both ends liquid crystal capacitance Cs needs
Maximum voltage Vmax is charged to from minimum voltage Vmin, then operational amplifier 93 can be by these P-type transistors and N-type transistor
It simultaneously turns on, flows through these P-type transistors to form charging current I+ and charge to liquid crystal capacitance Cs, and it is shown in Fig. 3
When the second time t2, according to one other pixel data, if output voltage Vout needs are discharged to most from maximum voltage Vmax
Small voltage Vmin, similarly, the operational amplifier 93 can simultaneously turn on these P-type transistors and N-type transistor, to form one
A discharge current I- is flowed to these N-type transistors by liquid crystal capacitance Cs and is discharged.Supplementary explanation: when these P-type crystals
When pipe and N-type transistor simultaneously turn on, a fixed current Istd is had by these P-type transistors and flows through these N-type transistors,
Therefore, according to Kirchhoff's current law (KCL) (Kirchhoff's Current Law, KCL), when liquid crystal capacitance Cs is charging
When, the total current Iin for flowing through these P-type transistors is the sum of charging current I+ and fixed current Istd, and works as the liquid crystal
When capacitor Cs is discharging, the total current Iout for flowing through these N-type transistors is discharge current I- and fixed current Istd
Sum.Specifically, when the range that the voltage Vout of liquid crystal capacitance Cs changes very greatly when it is (such as shown in Fig. 3 by minimum electricity
Pressure Vmin charges to maximum voltage Vmax, or is discharged to minimum voltage Vmin by maximum voltage Vmax), that is, need biggish fill
Electric current I+ or discharge current I- just can make the response speed of voltage Vout sufficiently fast liquid crystal capacitance Cs charge or discharge
Speed, however, not needing too big charging current I+/discharge current I- if the range of voltage Vout variation is smaller, can making
Liquid crystal capacitance Cs charge/discharge within the time limit is completed, and charging current I+/discharge current I- is bigger, represents to the liquid crystal capacitance
Power consumption when Cs charge/discharge is bigger, along with LCD screen constantly develops toward high-resolution, therefore, in order to save the energy,
Really need it is a set of may achieve energy conservation do not influence but drive efficiency mechanism.
Summary of the invention
Therefore, purpose of the present invention is to provide a kind of more energy efficient liquid crystal capacitance driving circuits.
Then, liquid crystal capacitance driving circuit of the present invention is suitable for being electrically connected a liquid crystal capacitance of a LCD screen, the liquid
Brilliant capacitor drive circuit includes a transmission unit, a converting unit, an output unit and a judging unit；The biography
It send unit to receive the pixel data of multiple numbers and transmits in order；The converting unit is electrically connected the transmission unit and is come from receiving
Each pixel data of the transmission unit, and it is electric according to the driving that each pixel data generates the corresponding pixel data
Pressure；The output unit is electrically connected the converting unit and the liquid crystal capacitance, and including an operational amplifier, the operation amplifier utensil
There are a prime control group, a first switch group being electrically connected between the prime control group and the liquid crystal capacitance and one
The second switch group being electrically connected between the prime control group and the liquid crystal capacitance；Judging unit be electrically connected to the transmission unit and
Between the output unit, and a comparison result signal is generated according to two pixel datas that the transmission unit successively transmits；When
The transmission unit transmits each pixel data to the converting unit, and the prime control group of the operational amplifier, which receives, comes from this turn
The driving voltage of unit and the corresponding pixel data is changed, and controls the first switch group and exports first electric current to the liquid crystal
Capacitor, so that the liquid crystal capacitance is charged or discharged to the driving voltage, the prime control group and according to comparison result signal control
Make whether the second switch group exports second electric current to the liquid crystal capacitance.
In some embodiments, each pixel data is binary data, and judging unit includes one and is electrically connected the biography
The memory of unit and the comparator of an electrical connection transmission unit and memory, memory is sent to receive and store transmission unit
The place value for judging position in this pixel data first transmitted in two pixel datas successively transmitted, the comparator receive the biography
This pixel data transmitted after in two pixel datas for sending unit successively to transmit, and judge the pixel data transmitted after this
In the place value that stores of the place value for judging position and memory it is whether identical, and generate comparison result signal.
In some embodiments, which is a latch.
In some embodiments, which is an XOR gate.
In some embodiments, liquid crystal capacitance driving circuit is also electrically connected a control unit；Wherein, judging unit also wraps
The buffer of an electrical connection comparator, control unit and output unit is included, buffer receives the comparison result from comparator
Signal, and export comparison result signal to the prime control of output unit according to a driving signal from the control unit
Group.
In some embodiments, which is one and door.
In some embodiments, each pixel data judges the position for the most significant bit of the pixel data.
Liquid crystal capacitance driving method of the present invention is executed by a liquid crystal capacitance driving circuit, the liquid crystal capacitance driving circuit electricity
The liquid crystal capacitance of LCD screen is connected, and includes transmission unit, converting unit, judging unit and output unit, the output unit
Including operational amplifier, the operational amplifier have prime control group, be electrically connected to the prime control group and the liquid crystal capacitance it
Between first switch group, and the second switch group being electrically connected between the prime control group and the liquid crystal capacitance, the liquid crystal capacitance
Driving method includes:
(A) transmission unit receives and transmits the first pixel data to converting unit；
(B) transmission unit receives and transmits the second pixel data to converting unit, and the second pixel data is sequence the
After one pixel data；
(C) judging unit generates a comparison result signal according to the first pixel data and the second pixel data；And
(D) the prime control group of the operational amplifier receives one from the converting unit and is relevant to second pixel
The driving voltage of data, and control the first switch group and export the first electric current to the liquid crystal capacitance, so that the liquid crystal capacitance is filled
Electricity is discharged to the driving voltage, and prime control group controls whether second switch group exports the second electric current according to comparison result signal
To the liquid crystal capacitance.
In some embodiments, judging unit has a memory, and the first pixel data and the second pixel data are
Numerical data with multidigit, liquid crystal capacitance driving method also include one between step (A) and step (B) the step of (E):
Memory receives and stores M place values of the first pixel data.
In some embodiments, judging unit also has comparator, and in step (C), comparator is received from memory
Place value, and the second pixel data from transmission unit, and judge place value and the second pixel data from the memory
Whether M place values are identical and generate comparison result signal.
In some embodiments, the first pixel data and the second pixel data are respectively one eight binary data, and
M of M of first pixel data and the second pixel data are respectively first pixel data and second pixel data
Most significant bit.
In some embodiments, liquid crystal capacitance driving circuit is also electrically connected a control unit, and judging unit also has one
A buffer, in step (C), buffer receives the comparison result signal from comparator, and comes from control unit according to one
Driving signal comparison result signal is exported to the prime control group of output unit.
In some embodiments, in step (D), the second pixel data is converted to corresponding second pixel data by converting unit
Driving voltage and be supplied to the prime control group of operational amplifier.
The effect of of the invention, is: generating one according to two pixel datas that transmission unit successively transmits by judging unit
Whether comparison result signal, the prime control group of operational amplifier export the further according to comparison result signal control second switch group
Two electric currents enable liquid crystal capacitance driving circuit that can adjust second switch group according to the voltage change degree of liquid crystal capacitance to liquid crystal capacitance
Whether conducting, and then the size to the electric current of liquid crystal capacitance charge/discharge is adjusted, and reaches effect of energy conservation.
Detailed description of the invention
The others feature and effect of volume of the present invention will be clearly presented in the embodiment referring to schema, in which:
Fig. 1 is circuit block diagram, illustrates that prior art liquid crystal capacitance driving circuit is electrically connected a liquid crystal capacitance；
Fig. 2 is circuit diagram, illustrates the internal circuit of the operational amplifier of prior art liquid crystal capacitance driving circuit；
Fig. 3 is waveform diagram, illustrate voltage of the prior art liquid crystal capacitance driving circuit to the liquid crystal capacitance charge/discharge when and
Current relationship；
Fig. 4 is circuit block diagram, illustrates that one embodiment of liquid crystal capacitance driving circuit of the present invention is electrically connected a liquid crystal
Capacitor；
Fig. 5 is the circuit diagram inside the operational amplifier of embodiment；
Fig. 6 is the action timing diagram of embodiment；
Fig. 7 is waveform diagram, when illustrating the second switch group conducting of embodiment, which fills the liquid crystal capacitance/
The voltage and current relationship of electric discharge；
Fig. 8 is waveform diagram, and when illustrating that the second switch group of embodiment is not turned on, operational amplifier is to liquid crystal capacitance discharge/charge
The voltage and current relationship of electricity；
Fig. 9 is schematic diagram, illustrates the relationship between the most significant digit of two contextual pixel datas of embodiment；
And
Figure 10 is schematic diagram, is illustrated between the most significant digit of other two contextual pixel data of the embodiment
Relationship.
Accompanying drawings symbol description
1 transmission unit
2 converting units
3 output units
31 operational amplifiers
311 prime control groups
312 first switch groups
313 second switch groups
4 judging units
41 reservoirs
42 comparators
43 buffers
9 liquid crystal capacitance driving circuits
91 bolt lock device groups
92 digital analog converters
93 operational amplifiers
100 control units
D0~Dn pixel data
V0~V255 driving voltage
Vout voltage
Vmin minimum voltage
Vmax maximum voltage
Vsync synchronization signal
Rn comparison result signal
The first driving signal of EN1
The second driving signal of EN2
EN3 third driving signal
I+ charging current
I- discharge current
Iin electric current
Iout electric current
Ip1 electric current
Ip2 electric current
In1 electric current
In2 electric current
Istd fixed current
Vcc power end
GND ground terminal
T1 is at the first time
Second time of t2
The t3 third time
The 4th time of t4
The 5th time of t5
The 6th time of t6
The 7th time of t7
The 8th time of t8
T_charge charge cycle
T_discharge discharge cycle
Cs liquid crystal capacitance
Specific embodiment
Refering to Fig. 4, one embodiment of liquid crystal capacitance driving circuit of the present invention is suitable for an electrical connections such as liquid crystal display
One liquid crystal capacitance Cs of curtain, and, for example, be the control unit 100 of central processing unit, liquid crystal capacitance Cs may actually be liquid
Brilliant equivalent capacity, or can also be additional actual capacitance, but be not limited thereto, which includes to pass
Send unit 1, converting unit 2, output unit 3 and judging unit 4.
The transmission unit 1 receives the pixel data of multiple numbers and transmits in order, in the present embodiment, each pixel
The binary data that data are eight, and first of each pixel data is the most significant digit of this pixel data
(Most Significant Bit,MSB)。
The converting unit 2 is electrically connected the transmission unit 1 to receive each pixel data from the transmission unit 1, and
The driving voltage of a corresponding pixel data is generated according to each pixel data, it more specifically, in the present embodiment, should
Converting unit 2 is a digital analog converter (Digital to Analog Converter, DAC), and can be by each picture
Prime number is converted to the driving voltage of an analog form according to the form by number.
Refering to Fig. 5, output unit 3 is electrically connected converting unit 2 and liquid crystal capacitance Cs, and including an operational amplifier 31.
The operational amplifier 31 has one prime control group 311, one and is electrically connected between prime control group 311 and liquid crystal capacitance Cs
First switch group 312 and a second switch group 313 being electrically connected between the prime control group 311 and liquid crystal capacitance Cs.
Specifically, in the present embodiment, as shown in figure 5, the tool of first switch group 312 there are two (being indicated in Fig. 5 with M=2) each other
P-type MOSFET (being indicated in Fig. 5 with P-MOS) that is in parallel and being electrically connected between a power end Vcc and liquid crystal capacitance Cs, and
One N-type MOSFET (In being electrically connected to (being indicated in Fig. 5 with M=1) between liquid crystal capacitance Cs and a ground terminal GND
Indicated in Fig. 5 with N-MOS), the tool of second switch group 313 is connected in parallel to each other there are six (being indicated with M=6) and is electrically connected to power end
P-type MOSFET between Vcc and liquid crystal capacitance Cs and three (being indicated with M=3) are electrically connected to liquid crystal capacitance Cs and ground terminal
N-type MOSFET between GND.
Judging unit 4 is electrically connected between transmission unit 1 and output unit 3, and two successively transmitted according to transmission unit 1
A pixel data generates a comparison result signal Rn.Judging unit 4 includes one and is electrically connected the transmission unit 1 and the control list
Member 100 41, comparators 42 for being electrically connected the transmission unit 1 and the memory 41 of memory and one be electrically connected the ratio
Compared with the buffer 43 of device 42, control unit 100 and output unit 3.In the present embodiment, which is a latch,
Comparator 42 is an XOR gate (XOR Gate), and buffer 43 is then one and door (AND Gate).Supplementary explanation: it passes
Sending unit 1 includes multiple latch (not shown)s, therefore also has the ability of storage numerical data.
Specifically, comparison result signal Rn caused by judging unit 4 is to represent transmission unit 1 to be sent to converting unit
Difference size between adjacent corresponding two driving voltages of pixel data in 2 two front and backs, for the present embodiment,
The binary data that each pixel data is eight, the voltage range segmentation that will also simulate are 256 (2 8 powers) a ranks
Layer, and each pixel data then represents the one of which of 256 kinds of driving voltages, for convenience of description, defines a minimum herein
A driving voltage V0 and maximum drive voltage V255.
In each cycle, which is sent to after a pixel data being changed into corresponding driving voltage
Output unit 3, output unit 3 drives liquid crystal capacitance Cs again with driving voltage, and constantly repeats this process, therefore, at each
In period, the voltage Vout on liquid crystal capacitance Cs can change between V0 to V255.
For example, refering to Fig. 9, the pixel data of minimum driving voltage V0 is corresponded to as [00000000], and its highest
Significance bit is 0, and the pixel data for corresponding to maximum drive voltage V255 is [11111111], and its most significant bit is 1, is taken
With refering to Fig. 4, if the voltage of liquid crystal capacitance Cs is originally used for minimum driving voltage V0 in some period, and next
In period, liquid crystal capacitance Cs need to be charged to maximum drive voltage V255, then the converting unit 2 is within two periods
The most significant digit of received two pixel datas will be different from each other respectively.
Again by way of further example for, while refering to Fig. 4 and Figure 10, if in some period, the voltage of liquid crystal capacitance Cs
It is originally used for the driving voltage V192 for being closer to maximum drive voltage V255, and in next cycle, liquid crystal capacitance Cs
Maximum drive voltage V255 need to be charged to, the pixel data of corresponding driving voltage V192 is [11000000], most significant bit
It is 1, and the pixel data for corresponding to maximum drive voltage V255 is [11111111], most significant bit is also 1, therefore the conversion
The most significant digit that unit 2 distinguishes received two pixel datas within two periods will be mutually the same.
In summary known to two: in the adjacent period of two front and backs, if two pictures of 2 received in sequence of converting unit
The most significant digit of prime number evidence is different, then the voltage Vout amplitude of variation for representing liquid crystal capacitance Cs is larger, conversely, if converting unit
The most significant digit of two pixel datas of 2 received in sequence is identical, then represents the voltage Vout amplitude of variation of liquid crystal capacitance Cs
It is smaller, more specifically, for eight binary data, 7 powers that weight representated by most significant digit is 2,
It is exactly 128, if the pressure difference between driving voltage representated by two pixel datas is more than 128 stratum, that is, is more than most therefore
The half of big mobility scale, then the most significant digit of two pixel datas must be different, therefore, before the present embodiment can be by comparing
Whether the most significant digit of latter two pixel data is identical and generates comparison result signal Rn, to judge the voltage of liquid crystal capacitance Cs
Vout variation degree is smaller or larger.
Belong to those skilled in the art of the present technique to know: if with a fixed current to a capacitor charge/discharge, the electricity
The size of voltage variety on container is the time being positively correlated with to its charge/discharge, that is to say, that if the capacitor is made to exist
Charge/discharge is completed in the shorter time, just driving capability need to be improved with biggish electric current, however, with biggish electric current to electricity
Container charge/discharge can consume biggish electric energy, therefore driving capability and the real difficult the two of energy conservation are taken into account, and the core function of the present embodiment
Effect is just: before liquid crystal capacitance Cs starts by charge/discharge, can judge the electricity of its current voltage Vout and target in advance
Whether the second switch group 313 pressed the difference size between Vout, and control output unit 3 is connected, by adjust output unit 3
To the charging current I+ or discharge current I- of liquid crystal capacitance Cs, and balance is obtained between driving capability and energy conservation consider.
It is described in detail below for the process of the present embodiment.Simultaneously refering to Fig. 4,
Fig. 5 and Fig. 6, firstly, when first time t1 shown in Fig. 6, the synchronization signal from the control unit 100
Vsync becomes 0 from 1, represents the starting of a cycle, meanwhile, the transmission unit 1 is according to first from the control unit 100
The the first pixel data D1 received and stored in advance is transmitted to the converting unit 2 by driving signal EN1, and the converting unit 2 will
First pixel data D1 is converted to corresponding first driving voltage and transmits it to the output unit 3.In Fig. 4, n is nature
Number, n are more than or equal to 1.
Then, in the second time t2, the prime control group 311 of the operational amplifier 31 receives first driving voltage,
And the first switch group 312 is controlled according to the second driving signal EN2 from the control unit 100 and exports the first electric current to the liquid
Brilliant capacitor Cs, so that liquid crystal capacitance Cs is charged or discharged before a third time t3 to first driving voltage.It adds
It is bright: to be to be electrically charged or be discharged according to liquid crystal capacitance Cs, which can be charging current I+ or the electric discharge
Electric current I-.
Then, in the 4th time t4, the memory 41 of judging unit 4 is according to the third driving from the control unit 100
Signal EN3 stores the place value of the most significant digit of first pixel data D1.
Then, as shown in FIG. 6 in the 5th time t5, synchronization signal Vsync becomes 0 from 1 again, represents another
The starting in period, meanwhile, the second pixel which receives and stores according to the first driving signal EN1 by one in advance
Data D2 is transmitted to the converting unit 2, and second pixel data D2 is converted to corresponding second driving electricity by the converting unit 2
It presses and transmits it to the output unit 3.
Then, it should be noted that: between the 5th time t5 and the 6th time t6, the comparator 42 of judging unit 4
The place value and the memory 41 for receiving the most significant digit of second pixel data D2 stored in upper a cycle first
The place value of the most significant digit of pixel data D1, and whether identical and generate a comparison result signal Rn both compare.Specifically
For, since the comparator 42 is an XOR gate, if the first pixel data D1 and second pixel data D2 most
The place value of big significance bit is identical, then comparison result signal Rn is 0, if it is different, then the comparison result signal Rn is 1.
Then, in the 6th time t6, the prime control group 311 of operational amplifier 31 receives the second driving voltage, and according to
The first switch group 312, which is controlled, according to second driving signal EN2 exports the first electric current to liquid crystal capacitance Cs, meanwhile, judging unit 4
Buffer 43 comparison result signal Rn is also transmitted to the prime control group of output unit 3 according to the second driving signal EN2
311, if comparison result signal Rn is 0, prime control group 311 controls second switch group 313 and is not turned on, conversely, if comparing knot
Fruit signal Rn is 1, then prime control group 311 controls second switch group 313 and is connected, to export the second electric current to liquid crystal capacitance Cs,
So that should go out unit 3 can provide bigger charging current I+ or discharge current I- and give liquid crystal capacitance Cs, make liquid crystal capacitance Cs the
It can be charged or discharged before seven time t7 to second driving voltage.
Finally, in the 8th time t8, the memory 41 of judging unit 4 according to third driving signal EN3 store this second
The place value of the most significant digit of pixel data D2, the source for comparator 42 in next cycle as comparison data.
After the 8th time t8, the as starting in another period, and judging unit 4 will be repeated continuously aforementioned step
The movement such as rapid comparison, control and storage, therefore just repeat no more.In addition, supplementary explanation: the first pixel data D1 is false
It is set as the 1 received first pixel data of institute of transmission unit in the present embodiment, therefore there is no more previous pixel data conducts
Comparison other, therefore when movement of the judging unit 4 between first time t1 and the second time t2 is in preceding description, ignores.
The movement of liquid crystal capacitance Cs charge or discharge is driven to be described in detail below for output unit 3, and respectively with liquid
Brilliant capacitor Cs is electrically charged, and the conducting of second switch group 313, liquid crystal capacitance Cs are discharged, and the conducting of second switch group 313, liquid crystal
Capacitor Cs is electrically charged, and second switch group 313 is not turned on and liquid crystal capacitance Cs is discharged, and second switch group 313 is not turned on
For four kinds of situations.
Simultaneously refering to Fig. 5 and Fig. 7, for example, in a charge cycle T_charge, if first driving voltage is
Minimum driving voltage V0, and second driving voltage be the maximum drive voltage V255 when, the second switch group 313 conducting,
Therefore the first switch group 312 and the second switch group 313 export charging current I+ to liquid crystal capacitance Cs jointly, more specifically
Say: electric current Iin is divided into electric current Ip1 and electric current Ip2 after being flowed by the power end Vcc of the operational amplifier 31, and respectively flows through this
The p-type MOSFET of the first switch group 312 and p-type MOSFET of the second switch group 313, then, electric current Ip1 and electric current Ip2 are each
There is part to flow to liquid crystal capacitance Cs and form charging current I+, and electric current Ip1 and electric current Ip2 do not flow to liquid crystal capacitance Cs
Part be then respectively defined as electric current In1 and electric current In2, and respectively flow through the first switch group 312 N-type MOSFET and should
The N-type MOSFET of second switch group 313, finally, electric current In1, electric current In2 and charging current I+ confluence are electric current Iout and flow to
The ground terminal GND of the operational amplifier 31.It should be noted that: in the present embodiment, the p-type MOSFET's of second switch group 313
Quantity is three times of first switch group 312, and the quantity of the N-type MOSFET of second switch group 313 is also first switch group 312
Three times, in other words, when second switch group 313 is connected, the electric current for flowing through second switch group 313 is also first switch group 312
Three times, more particularly: when second switch group 313 be connected when, second switch group 313 provide driving liquid crystal capacitance Cs it
The 75% of total electric energy, and first switch group 312 provides the 25% of total electric energy of driving liquid crystal capacitance Cs, therefore, electric current Ip1
Be essentially electric current Iin 25%, electric current Ip2 be essentially the 75% of electric current Iin, and electric current In2 is three times of electric current In1,
But it is not limited in other embodiments with above-mentioned.
With continued reference to Fig. 5 and Fig. 7, in discharge cycle T_discharge, if the first driving voltage is maximum drive electricity
Press V255, and the second driving voltage be the minimum driving voltage V0 when, second switch group 313 be connected, therefore one come from the liquid crystal
The discharge current I- of capacitor Cs flow to ground terminal GND via first switch group 312 and second switch group 313, more specifically: electricity
Stream Iin is divided into electric current Ip1 and electric current Ip2 after being flowed by power end Vcc, and respectively flows through the p-type of the first switch group 312
The p-type MOSFET of MOSFET and the second switch group 313, and electric current Ip1 is the 25% of electric current Iin, electric current Ip2 is electric current Iin
75%, then, the 25% of discharge current I- is electric current In1 with electric current Ip1 confluence and flows through the N-type of first switch group 312
MOSFET, the 75% of discharge current I- and electric current Ip2, which converge, to be electric current In2 and flows through the N-type MOSFET of second switch group 313,
Finally, electric current In1 and electric current In2 confluence is electric current Iout and flow to ground terminal GND.
Simultaneously refering to Fig. 5 and Fig. 8, in another charge cycle T_charge, if the first driving voltage is driving voltage
V192, and the second driving voltage be the maximum drive voltage V255 when, which is not turned on, therefore only first opens
Pass group 312 exports charging current I+ to liquid crystal capacitance Cs, more specifically: electric current Iin is flowed only through after being flowed by power end Vcc
The p-type MOSFET of first switch group 312, in other words, electric current Ip2 is zero, and electric current Ip1 is equal to electric current Iin, then, electric current
Ip1 has part to flow into liquid crystal capacitance Cs and form charging current I+, and electric current Ip1 does not flow into the part of liquid crystal capacitance Cs then
It is defined as electric current In1 and flows through the N-type MOSFET of the first switch group 312, finally, electric current In1 and charging current I+ confluence
For electric current Iout and it flow to ground terminal GND.
With continued reference to Fig. 5 and Fig. 8, in another discharge cycle T_discharge, if the first driving voltage is the maximum
Driving voltage V255, and the second driving voltage be driving voltage V192 when, second switch group 313 is not turned on, and from liquid crystal electricity
The discharge current I- for holding Cs only flow to ground terminal GND via first switch group 312, and more specifically: electric current Iin is by the power end
Vcc flows only through the p-type MOSFET of the first switch group 312 after flowing into, in other words, electric current Ip2 is zero, and electric current Ip1 is equal to
Electric current Iin, then, discharge current I- and electric current Ip1 confluence are electric current In1 (i.e. electric current Iout) by by first switch group 312
N-type MOSFET flow to ground terminal GND.
Compare Fig. 7 and Fig. 8 and arrange in pairs or groups refering to known to Fig. 5: the voltage Vout variation range in Fig. 7, on liquid crystal capacitance Cs
It is larger, therefore the second switch group 313 is connected, therefore the output unit 3 charging current I+ that can provide or discharge current I- is larger, and
There can be stronger driving capability, and in fig. 8, the voltage Vout variation range on liquid crystal capacitance Cs is smaller without to drive with all strength
It is dynamic, therefore second switch group 313 is not turned on, therefore other than the size in addition to reducing charging current I+ and discharge current I-, electric current Ip2 and
Electric current In2 is also zero, and reduces power consumption, reaches effect of energy conservation.
In conclusion the judging unit 4 of liquid crystal capacitance driving circuit of the present invention liquid crystal capacitance Cs start charge/discharge it
Before, the difference size between its current voltage Vout and the voltage Vout of target can be judged in advance and generates comparison result signal
Rn, whether prime control group 311 is connected further according to comparison result signal Rn control second switch group 313, to adjust to liquid crystal electricity
The size for holding the charging current I+ or discharge current I- of Cs, when so that the voltage Vout variation range on liquid crystal capacitance Cs is larger,
Output unit 3 can provide enough driving capabilities, and when the voltage Vout variation range on liquid crystal capacitance Cs is smaller, it can be reduced
The power consumption of output unit 3 and reach energy conservation, balance can be obtained between driving capability and energy conservation consider as a result, therefore really
The purpose of the present invention can be reached.
Only as described above, only embodiments of the present invention are all when the range that cannot limit implementation of the invention with this
It is the simple equivalent changes and modifications made according to scope of the present invention patent and patent specification content, all still belongs to the present invention
In the range that patent covers.
Claims (12)
1. a kind of liquid crystal capacitance driving circuit, suitable for being electrically connected the liquid crystal capacitance of LCD screen, the liquid crystal capacitance driving circuit
Include:
Transmission unit receives the pixel data of multiple numbers and transmits in order, each pixel data is binary data；
Converting unit is electrically connected the transmission unit to receive each pixel data from the transmission unit, and according to each
A pixel data generates the driving voltage of a corresponding pixel data；
Output unit is electrically connected the converting unit and the liquid crystal capacitance, and including an operational amplifier, the operation amplifier utensil
There are a prime control group, a first switch group being electrically connected between the prime control group and the liquid crystal capacitance and one
The second switch group being electrically connected between the prime control group and the liquid crystal capacitance；And
Judging unit, the reservoir including being electrically connected transmission unit, and the comparator of electrical connection transmission unit and reservoir, storage
Device receives and stores the place value for judging position in the pixel data first transmitted in two pixel datas that transmission unit successively transmits,
The pixel data that comparator transmits after receiving in two pixel datas that transmission unit successively transmits, and the pixel transmitted after judging
Whether the place value for judging position in data and the place value that the reservoir stores are identical, and generate comparison result signal；
When the transmission unit transmits each pixel data to the converting unit, the prime control group of the operational amplifier, which receives, to be come
From the converting unit and the driving voltage of the corresponding pixel data, and controls first switch group and export first electric current to liquid
Brilliant capacitor, so that liquid crystal capacitance is charged or discharged to driving voltage, prime control group and according to comparison result signal control the
Whether two switching groups export the second electric current to the liquid crystal capacitance.
2. liquid crystal capacitance driving circuit as described in claim 1, wherein the reservoir is a latch.
3. liquid crystal capacitance driving circuit as described in claim 1, wherein the comparator is an XOR gate.
4. liquid crystal capacitance driving circuit as described in claim 1 is also electrically connected a control unit；Wherein, judging unit is also
Be electrically connected the buffer of comparator, control unit and output unit including one, buffer receive from comparator this compare
Consequential signal, and export comparison result signal to the prime of output unit according to a driving signal from the control unit
Control group.
5. liquid crystal capacitance driving circuit as claimed in claim 4, wherein the buffer is one and door.
6. the liquid crystal capacitance driving circuit as described in any item of claim 1 to 5, wherein each pixel data is sentenced
Disconnected position is the most significant bit of the pixel data.
7. a kind of liquid crystal capacitance driving method, is executed by a liquid crystal capacitance driving circuit, which is electrically connected
The liquid crystal capacitance of LCD screen is connect, and includes a transmission unit, a converting unit, a judging unit and an output
Unit, the output unit include an operational amplifier, which is electrically connected to a prime control group, one
First switch group between the prime control group and the liquid crystal capacitance and one are electrically connected to the prime control group and liquid crystal electricity
Second switch group between appearance, which includes:
(A) transmission unit receives and transmits first pixel data to converting unit；
(B) transmission unit receives and transmits second pixel data to converting unit, and the second pixel data is sequence the
After one pixel data；
(C) judging unit generates comparison result signal according to first pixel data and second pixel data；And
(D) the prime control group of operational amplifier receives from the converting unit and is relevant to the driving electricity of the second pixel data
Pressure, and control first switch group and export the first electric current to liquid crystal capacitance, so that the liquid crystal capacitance is charged or discharged to the driving
Voltage, prime control group simultaneously control whether second switch group exports the second electric current to the liquid crystal capacitance according to comparison result signal.
8. liquid crystal capacitance driving method as claimed in claim 7, wherein judging unit has a reservoir, and the first picture
Prime number evidence and the second pixel data are the numerical datas with multidigit, and liquid crystal capacitance driving method also includes one in step (A)
And the step of between step (B) (E): reservoir receives and stores M place values of the first pixel data.
9. liquid crystal capacitance driving method as claimed in claim 8, wherein judging unit also has a comparator, in step
(C), comparator receives the place value from reservoir, and the second pixel data from transmission unit, and judges from storage
Whether the place value of device is identical as M place values of the second pixel data and generates the comparison result signal.
10. liquid crystal capacitance driving method as claimed in claim 9, wherein the first pixel data and the second pixel data are
Eight binary data, and M of M of the first pixel data and the second pixel data are respectively the first pixel datas
And second pixel data most significant bit.
11. liquid crystal capacitance driving method as claimed in claim 9, wherein liquid crystal capacitance driving circuit is also electrically connected a control
Unit processed, judging unit also have a buffer, and in step (C), buffer receives the comparison result letter from the comparator
Number, and export comparison result signal to the prime control of the output unit according to a driving signal from the control unit
Group.
12. the liquid crystal capacitance driving method as described in any item of claim 7 to 11, in step (D), converting unit is by
Two pixel datas are converted to the driving voltage of corresponding second pixel data and are supplied to the prime control group of operational amplifier.
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| CN101320178A (en) * | 2007-06-08 | 2008-12-10 | 奇美电子股份有限公司 | LCD device, liquid crystal display panel and its driving method |
| TWI421851B (en) * | 2011-05-17 | 2014-01-01 | Au Optronics Corp | Liquid crystal display having common voltage compensation mechanism and common voltage compensation method |
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