The disclosure relates in general to control methods of a channel setting module applied to a display panel, and more particularly to control methods of a channel setting module applied to a display panel capable of depressing coupling effects between source lines.
In the specification, different capital variables are utilized to represent the number of components. These variables (for example, X, Y, M, J) are positive integers, and their lowercase letters are utilized to represent the generalized item. The signal lines and the signals being transmitted by the signal lines are represented as the same symbols. For example, the source lines and the signals being transmitted through the source lines are represented as SL.
The display panel 11 includes pixels 11a being arranged in a matrix, X source lines SL[1]˜SL[X], and Y gate lines GL[1]˜GL[Y]. Colors and types of the pixels 11a are not limited. For example, the pixels 11a can be red pixels, green pixels, or blue pixels, and the pixels 11a can be OLED pixels, LCD pixels, and so forth.
The pixels 11a disposed at the same column are electrically connected to the same source line SL, and the pixels 11a disposed at the same row are electrically connected to the same gate line GL. For example, the pixels 11a disposed at the first column are electrically connected to the source line DL[1], and the pixels 11a disposed at the X-th column are electrically connected to the source line SL[X]. Similarly, the pixels 11a disposed at the first row are electrically connected to the gate line GL[1], and the pixels disposed at the Y-th row are electrically connected to the gate line GL[Y]. For the sake of illustration, the pixels 11a disposed at the y-th row are described.
The timing controller 12 alternately controls the pixels 11a in a row-by-row manner. In the horizontal line duration T_pln(y) (wherein y=1˜Y), the timing controller 12 transmits source control signals Ssrc_ctl, corresponding to the X pixels 11a disposed at the y-th row, to the source driver 13.
The de-multiplexing technique is adopted to reduce the manufacturing cost of the source driver 13. As shown in
Once the de-multiplexing technique is utilized, the timing controller 12 does not need to control all the source lines SL[1]˜SL[X] simultaneously. Instead, the timing controller 12 sends the source control signals Ssrc_ctl in a time-division approach. That is, for the J source lines being electrically connected to the m-th channel setting module setMDL_m, only the j-th source line (SLmj) receives the output voltage from the m-th channel setting module setMD_m in the j-th de-multiplexed duration. The mapping between the source line SL[1]˜SL[X] and the channel setting modules setMDL_1˜setMDL_M can be summarized in Table 1.
Between time point t2 and time point t3, the source line SL[x](wherein x=1˜X) is biased by the output voltage so that the potential of the source line SL[x] rises to the predefined pixel voltage Vpxl. The predefined pixel voltage Vpxl corresponds to the luminous intensity of the pixel 11a disposed at the x-th column and the y-th row.
Between time point t3 and time point t4, the source line SL[x] becomes floating. In this duration, the potential of the source line SL[x] might be affected by the potential of its adjacent source line (for example, the source line SL[x+1]), which is biased in the meanwhile.
The use of the de-multiplexing technique implies that the source lines connected to the same channel setting module are biased alternately. Due to the coupling effects between the source lines, the potential of the source line, which has been biased previously, might be affected by the source line being biased later.
For example, an overshoot of the source line SL[x] occurs soon after time point t3. The overshoot results in that the potential of the x-th source line SL[x] becomes slightly higher than the predefined pixel voltage Vpxl, with a pixel voltage error ΔV. Consequently, the luminous intensity of the pixel 11a disposed at the x-th column and the y-th row deviates. Therefore, the coupling effects between the driven (biased) source lines and the floating source lines become an issue.
Please note that the coupling effects between source lines might result in undershoot as well. The types and amplitudes of the phenomenon caused by coupling are determined by the polarity and values of the neighboring source line being driven.
The disclosure is directed to control methods of a channel setting module applied to a display panel. The channel setting module dynamically provides output voltages to source lines of the display panel as channel inputs. The voltages of the source lines may suffer unexpected change when de-multiplexer switching circuits are adopted for saving cost, and the control methods proposed in the present disclosure are capable of depressing such unexpected variation of the floating channels.
According to one embodiment, a control method of a channel setting module applied to a display panel is provided. The channel setting module includes a first operational amplifier and a second operational amplifier. The control method includes the following steps. In a first de-multiplexed duration, an output voltage of the first operational amplifier is supplied to a first source line of the display panel, and an output voltage of the second operational amplifier is supplied to a second source line of the display panel. In a second de-multiplexed duration, the output voltage of the first operational amplifier is supplied to a third source line of the display panel, and the output voltage of the second operational amplifier is supplied to the second source line of the display panel. Ina third de-multiplexed duration, the output voltage of the first operational amplifier is supplied to the third source line of the display panel, and the output voltage of the second operational amplifier is supplied to a fourth source line of the display panel. The first de-multiplexed duration is before the second de-multiplexed duration, and the second de-multiplexed duration is before the third de-multiplexed duration.
According to another embodiment, a control method of a channel setting module applied to a display panel is provided. The channel setting module includes a first and a second operational amplifiers. The control method includes the following steps. In a first de-multiplexed duration, an output voltage of the first operational amplifier is supplied to a first source line of the display panel, and an output voltage of the second operational amplifier is supplied to a second source line of the display panel. In a second de-multiplexed duration, the output voltage of the first operational amplifier is supplied to a third source line of the display panel, and the output voltage of the second operational amplifier is supplied to a fourth source line of the display panel. Ina third de-multiplexed duration, the output voltage of the first operational amplifier is supplied to the first source line, and the output voltage of the second operational amplifier is supplied to the second source line. The first de-multiplexed duration is before the second de-multiplexed duration, and the second de-multiplexed duration is before the third de-multiplexed duration.
According to an alternative embodiment, a control method of a channel setting module applied to a display panel is provided. The display panel includes a first, a second, a third, and a fourth source lines, and the channel setting module includes a first and a second operational amplifiers. The control method includes the following steps. Firstly, a first, a second, a third, and a fourth converted signals are received from a first, a second, a third, and a fourth converting circuits, respectively. Then, the first converted signal is amplified, by the first operational amplifier, to generate an output voltage of the first operational amplifier, and the second converted signal is amplified, by the second operational amplifier, to generate an output voltage of the second operational amplifier. In a first de-multiplexed duration, the output voltage of the first operational amplifier is supplied to one of the third source line and the fourth source line, and the output voltage of the second operational amplifier is supplied to the other of the third source line and the fourth source line. In a second de-multiplexed duration, the output voltage of the first operational amplifier is supplied to one of the first source line and the second source line, the output voltage of the second operational amplifier is supplied to the other of the first source line and the second source line, the third converted signal is conducted to the one of the third source line and the fourth source line, and the fourth converted signal is conducted to the other of the third source line and the fourth source line. The first de-multiplexed duration is before the second de-multiplexed duration.
In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
To suppress the unexpected potential changes of the floating source lines SL, different embodiments are illustrated below. In the following embodiments, the channel setting modules setMDL_m are assumed to correspond to J=4 source lines (SLm1, SLm2, SLm3, SLm4). Nevertheless, with appropriate modifications, the control methods described below can also be applied to the channel setting modules setMDL_m corresponding to the different number of source lines SL.
The source control modules srcMDL_m includes first stage latches L1a, L1b, second stage latches L2a, L2b, level shifters pLVSHT, nLVSHT, and converting circuits pDAC, nDAC. The converting circuits pDAC, nDAC are digital-to-analog converters used for converting digital video data (hereinafter, driving signals Sdrv1, Sdrv2) into analog data voltages (hereinafter, converted signals Scnv1, Scnv2).
The second stage latch L2a is electrically connected to the first stage latch L1a and the level shifter pLVSHT. The second stage latch L2b is electrically connected to the first stage latch L1b and the level shifter nLVSHT. The converting circuit pDAC is electrically connected to the level shifter pLVSHT and the channel setting module setMDL_m, and the converting circuit nDAC is electrically connected to the level shifter nLVSHT and the channel setting module setMDL_m.
In the first and the second embodiments, the source control signals Ssrc_ctl include video signals for the first stage latches L1a, L1b, the loading signal LD for the second stage latches L2a, L2b, and the switch-setting signals for controlling de-mux switches in the buffer 30a. The first stage latches L1a, L1b receive video signals from the timing controller. Then, the first stage latches L1a, L1b respectively generate pre-data Spre1, Spre2 to the second stage latches L2a, L2b. Later, the second stage latches L2a, L2b generate and transmit the latched data Slat1, Slat2 to the level shifters pLVSHT, nLVSHT, in response to the loading pulse of the loading signal LD. The level shifters pLVSHT, nLVSHT respectively generate the driving signals Sdrv1, Sdrv2 based on the latched data Slat1, Slat2. The converting circuits pDAC, nDAC respectively receive the driving signals Sdrv1, Sdrv2 from the level shifters pLVSHT, nLVSHT, convert the driving signals Sdrv1, Sdrv2 to the converted signals Scnv1, Scnv2, and transmit the converted signals Scnv1, Scnv2 to the channel setting module setMDL_m.
The channel setting module setMDL_m further includes a buffer 30a and a de-multiplexer switching circuit 30b. The buffer 30a includes the operational amplifiers op1, op2, and the de-mutiplexer switching circuit 30b includes de-mux switches sw11, sw22, sw13, sw24. The operational amplifier op1 amplifies the converted signal Scnv1 to generate the output voltage Sout1, and the operational amplifier op2 amplifies the converted signal Scnv2 to generate the output voltage Sout2. The de-mux switches sw11, sw22, sw13, sw24 are selectively turned on/off.
The operational amplifier op1 is electrically connected to the converting circuit pDAC, and the de-mux switches sw11, sw13. The operational amplifier op2 is electrically connected to the converting circuit nDAC, and the de-mux switches sw22, sw24. The de-mux switches sw11, sw22, sw13, sw24 are respectively electrically connected to the source lines SLm1, SLm2, SLm3, SLm4.
The pixels, which are corresponding to the channel setting module setMDL_m and disposed at the y-th row, are shown. The pixels pxlm1y, pxln2y, pxlm3y, pxlm4y are jointly electrically connected to the gate line GL[y], and the pixels pxlm1y, pxlm2y, pxlm3y, pxlm4y are respectively electrically connected to the source lines SLm1, SLm2, SLm3, SLm4. When the de-mux switch sw11 is turned on, the output voltage Sout1 of the operational amplifier op1, being equivalent to the pixel voltage Vm1y, is transmitted to the pixel pxlm1y through the de-mux switch sw11. The operations of other de-mux switches sw22, sw13, sw24 are similar.
In
The state of the channel setting module setMDL_m in
The state of the channel setting module setMDL_m in
In the specification, the switch-setting signals Ssw are labeled with symbols of their corresponding de-mux switches. For example, the switch-setting signals Ssw11, Ssw22, Ssw13, Ssw24 are respectively utilized for controlling de-mux switches sw11, sw22, sw13, sw14. The de-mux switches sw11, sw22, sw13, sw14 of the channel setting module setMDL_m in
The de-mux switches sw11, sw22, sw13, sw24 are controlled in a time-division manner. The actual control sequences of the de-mux switches sw11, sw22, sw13, sw24 are different, based on different embodiments. In the specification, the first embodiment (
To illustrate the control methods according to the present disclosure, waveforms are utilized to represent how the signals are controlled. Please note that the voltage levels, amplitudes, and polarities of the waveforms are shown for illustration purposes only, and they might be varied in practical applications.
The gate pulse of the gate line GL[y] is utilized to enable the pixels of the y-th row. In the specification, the gate pulse is assumed to be a positive pulse, but it might be a negative pulse in some applications.
In
Between time point t3 and time point t4, the loading signal LD maintains at the on-level. That is, the loading signal LD generates a loading pulse between teme point t3 and time point t4. The loading signal LD is a global signal sent to all channel setting modules setMDL_1˜setMDL_M. In response to the loading pulse, the second stage latches L2a, L2b respectively receives the pre-data Spre1, Spre2 from the first stage latches L1a, L1b. Moreover, the operational amplifiers op1, op2 starts to amplify the converted signals Scnv1, Scnv2, and generate output voltages Sout1, Sout2 accordingly. The loading signal LD transits from the on-level to the off-level at time point t4.
At time point t4, the switch-setting signal Ssw11 transits from the off-level to the on-level. The switch-setting signal Ssw11 transits from the on-level to the off-level at time point t5. Therefore, the de-mux switch sw11, being controlled by the switch-setting signal Ssw11, is turned on between time point t4 and time point t5.
At time point t4, the switch-setting signal Ssw22 transits from the off-level to the on-level. The switch-setting signal Ssw22 transits from the on-level to the off-level at time point t7. Therefore, the de-mux switch sw22, being controlled by the switch-setting signal Ssw22, is turned on between time point t4 and time point 7.
At time point t6, the switch-setting signal Ssw13 transits from the off-level to the on-level. The switch-setting signal Ssw13 transits from the on-level to the off-level at time point t10. Between time point t6 and time point t10, the switch-setting signal Ssw13 remains at the on-level. Therefore, the de-mux switch sw13, being controlled by the switch-setting signal Ssw13, is turned on between time point t6 and time point t10.
At time point t8, the switch-setting signal Ssw24 transits from the off-level to the on-level. The switch-setting signal Ssw24 transits from the on-level to the off-level at time point t10. Therefore, the de-mux switch sw24, being controlled by the switch-setting signal Ssw24, is turned on between time point t8 and time point t0. The waveforms of the switch-setting signals Ssw11, Ssw22, Ssw13, Ssw24 described above result in the following potential changes of the source lines SLm1, SLm2, SLm3, SLm4.
Between time point t4 and time point t5 (the de-multiplexed duration Tdmux1), the channel setting module setMDL_m is at the setting state STa (
Between time point t5 and time point t6 (gap duration ΔTg1), the channel setting module setMDL_m is at a transition state between the setting state STa and the setting state STb. In the transition state, the de-mux switch sw11, sw13, sw24 are turned off because the switch-setting signals Ssw11, Ssw13, Ssw24 are at the off-level, and the de-mux switch sw22 is turned on because the switch-setting signal Ssw22 is at the on-level. Therefore, the source lines SLm1, SLm3, SLm4 are floating, and the source line SLm2 is biased.
Although the source line SLm1 stops receiving the output voltage Sout1 after time point t5, the potential of the source line SLm1 remains at the pixel voltage Vm1y because the potential of its adjacent source line SLm2 remains constant between time point t5 and time point t7. That is, as there is no significant change of the potential of the source line SLm2 by the time the source line SLm1 stops receiving the output voltage Sout1, the potential of the floating source line SLm1 can remain unchanged.
Between time point t6 and time point t7 (the de-multiplexed duration Tdmux2), the channel setting module setMDL_m is at the setting state STb (
Between time point t7 and time point t8 (the gap duration ΔTg2), the channel setting module setMDL_m is at a transition state between the setting state STb and the setting state STc. In the transition state, the de-mux switch sw11, sw22, sw24 are turned off because the switch-setting signals Ssw11, Ssw22, Ssw24 are at the off-level, and the de-mux switch sw13 is turned on because the switch-setting signal Ssw13 is at the on-level. Therefore, the source lines SLm1, SLm2, SLm4 are floating, and the source line SLm3 is biased.
The source line SLm2 has two adjacent source lines SLm1, SLm3. The source line SLm1 is floating by the time the source line SLm2 stops receiving the output voltage Sout2. Therefore, the potential of the source line SLm1 does not affect the potential of the source line SLm2. Although the source line SLm2 stops receiving the output voltage Sout2 after time point t7, the potential of the source line SLm2 remains at the pixel voltage Vm2y because the potential of the source line adjacent to the source line SLm2 (that is, the source line SLm3) remains unchanged between time point t7 and time point t8. That is, as there is no sudden change of the source line SLm3 by the time the source line SLm2 stops receiving the output voltage Sout2, the potential of the floating source line SLm2 can remain unchanged. Accordingly, none of the potentials of the source lines SLm1, SLm3 would affect the potential of the source line SLm2.
Between time point t8 and time point t10 (the de-multiplexed duration Tdmux3), the channel setting module setMDL_m is at the setting state STc (
As shown in
In the first embodiment, the de-multiplexed durations Tdmux1, Tdmux3 are mainly used for providing output voltages Sout1, Sout2, Sout3, Sout4 to the source lines SLm1, SLm2, SLm3, SLm4, and the de-multiplexed duration Tdmux2 is mainly used for eliminating the potential coupling effect. During the de-multiplexed duration Tdmux2, potential changes of the source lines SLm1, SLm3 are specially managed to avoid the occurrence of the coupling effects. The length of the de-multiplexed duration Tdmux1 is longer than the length of the de-multiplexed duration Tdmux2, and the de-multiplexed duration Tdmux3 is longer than the length of the de-multiplexed duration Tdmux2. In some applications, the length of the de-multiplexed duration Tdmux1 is equivalent to the length of the de-multiplexed duration Tdmux3. The state-changing sequence of the channel setting module setMDL_m in the first embodiment is summarized in Table 3.
In
Between time point t3 and time point t4, a loading pulse is generated. In response to the loading pulse, the second stage latches L2a, L2b receives the pre-data Spre1, Spre2 from the first stage latches L1a, L1b, and the level shifters pLVSHT, nLVSHT, and the converting circuits pDAC, nDAC also proceed their operations. Then, at time point t4, the operational amplifiers op1, op2 start to amplify the converted signals Scnv1, Scnv2, and generate the output voltages Sout1, Sout2 accordingly.
At time point t4, the switch-setting signals Ssw11, Ssw22 transit from the off-level to the on-level. The switch-setting signal Ssw11, Ssw22 transit from the on-level to the off-level at time point t5. Therefore, the de-mux switches sw11, sw22 are turned on between time point t4 and time point t5.
At time point t6, the switch-setting signals Ssw13, Ssw24 transit from the off-level to the on-level. The switch-setting signals Ssw13, Ssw24 transit from the on-level to the off-level at time point t7. Therefore, the de-mux switches sw13, sw24 are turned on between time point t6 and time point t7.
At time point t8, the switch-setting signals Ssw11, Ssw22 transit from the off-level to the on-level. The switch-setting signals Ssw11, Ssw22 transit from the on-level to the off-level at time point t11. Therefore, the de-mux switches sw11, sw22 are turned on between time point t8 and time point t11. The above-described of the waveforms of the switch-setting signals Ssw11, Ssw22, Ssw13, Ssw24 result in the following potential changes of the source lines SLm1, SLm2, SLm3, SLm4, as described above.
Between time point t4 and time point t5 (the de-multiplexed duration Tdmux1), the channel setting module setMDL_m is at the setting state STa (
Between time point t5 and time point t6 (the gap duration ΔTg1), the channel setting module setMDL_m is at a transition state between the setting state STa and the setting state STc. In the transition state, the de-mux switches sw11, sw22, sw13, sw24 are all turned off because the switch-setting signals Ssw11, Ssw22, Ssw13, Ssw24 are at the off-level.
Between time point t6 and time point t7 (the de-multiplexed duration Tdmux2), the channel setting module setMDL_m is at the setting state STc (
Between time point t7 and time point t8 (the gap duration ΔTg2), the channel setting module setMDL_m is at a transition state between the setting state STc and the setting state STa. In the transition state, the de-mux switch sw11, sw22, sw13, sw24 are all turned off because the switch-setting signals Ssw11, Ssw22, Ssw13, Ssw24 are at the off-level. During the gap duration ΔTg2, the potential of the source line SLm1 is slightly higher than or equivalent to the pixel voltage Vm1y, the potential of the source line SLm2 is slightly higher than the pixel voltage Vm2y, the potential of the source line SLm3 is equivalent to the pixel voltage Vm3y, and the potential of the source line SLm4 is equivalent to the pixel voltage Vm4y.
Between time point t8 and time point t11 (the de-multiplexed duration Tdmux3), the channel setting module setMDL_m is at the setting state STa (
As shown in
In
When m≠1, the source line SLm1 has two adjacent source lines, including the source line SLm2 in the channel setting module setMDL_m and the source line SLm4 in the channel setting module setMDL_(m−1). As the source lines SLm1, SLm2 in the channel setting module setMDL_m receive the output voltages Sout1, Sout2 synchronously, the source line SLm2 does not affect the potential of the source line SLm1. However, the source line SLm1 might be affected by the potential of the source line SLm4 in the channel setting module setMDL_(m−1) when m≠1. Therefore, when m≠1, the potential changes of the source line SLm1 are similar to those of the source line SLm2.
In the second embodiment, the de-multiplexed duration Tdmux1, Tdmux2 is mainly used for providing pixel voltages Vm1y, Vm2y to the source lines SLm1, SLm2, the de-multiplexed duration Tdmux2 is mainly used for providing pixel voltages Vm3y, Vm4y to the source lines SLm3, SLm4, and the de-multiplexed duration Tdmux2 is mainly used for compensating the side effect of the coupling. Therefore, the potential of the source lines SLm1, SLm2 are recovered to the pixel voltages Vm1y, Vm2y in the de-multiplexed duration Tdmux3, although their potentials are affected in the de-multiplexed duration Tdmux2. The length of the de-multiplexed duration Tdmux1 is longer than the length of the de-multiplexed duration Tdmux2, and the de-multiplexed duration Tdmux2 is longer than the length of the de-multiplexed duration Tdmux3. In some applications, the length of the de-multiplexed duration Tdmux1 is equivalent to the length of the de-multiplexed duration Tdmux2. The state-changing sequence of the channel setting module setMDL_m in the second embodiment is summarized in Table 4.
The OLED display panels and the LCD panels are widely used in display devices. The LCD panels use polarity inversion, for example, dot inversion, line inversion, column inversion, frame inversion, and so forth, to prevent damages. Therefore, the polarity inversion function needs to be concerned for the source drivers of LCD panels.
Shown in solid lines, the polarity control switches sw_po, sw_ne are parallel to each other. The polarity control switch sw_po is electrically connected to the operational amplifier op1 and the polarity terminal Np1. The polarity control switch sw_ne is electrically connected to the operational amplifier op2 and the polarity terminal Np2. The polarity control switches sw_po, sw_ne are turned on when the polarity setting signal PL is at the on-level (PL=1), and the polarity control switches sw_po, sw_ne are turned off when the polarity setting signal PL is at the off-level (PL=0).
Shown in dotted lines, the polarity control switches sw_pe, sw_no are cross-coupled. The polarity control switch sw_pe is electrically connected to the operational amplifier op1 and the polarity terminal Np2. The polarity control switch sw_no is electrically connected to the operational amplifier op2 and the polarity terminal Np1. The polarity control switches sw_pe, sw_no are turned off when the polarity setting signal PL is at the on-level (PL=1), and the polarity control switches sw_pe, sw_no are turned on when the polarity setting signal PL is at the off-level (PL=0).
In both
The source control modules srcMDL_m includes the first stage latches L1a, L1b, the second stage latches L2a, L2b, L2c, L2d, the level shifters p1LVSHT, n1LVSHT, p2LVSHT, n2LVSHT, and the converting circuits p1DAC, n1DAC, p2DAC, n2DAC.
The second stage latches L2a, L2c are electrically connected to the first stage latch L1a, and the second stage latches L2b, L2d are electrically connected to the first stage latch L1b. The level shifters p1LVSHT, n1LVSH, p2LVSH, n2LVSH are respectively electrically connected to the second stage latches L2a, L2b, L2c, L2d. The converting circuits p1DAC, n1DAC, p2DAC, n2DAC are respectively electrically connected to the level shifters p1LVSHT, n1LVSHT, p2LVSHT, n2LVSHT.
The first stage latches L1a, L1b receive video signals from the timing controller. Then, the first stage latches L1a, L1b respectively generate pre-data Spre1, Spre2. Later, the second stage latches L2a, L2b, L2c, L2d respectively generate and transmit the latched data Slat1, Slat2, Slat3, Slat4 to the level shifters p1LVSHT, n1LVSHT, p2LVSHT, n2LVSHT.
The converting circuits p1DAC, n1DAC, p2DAC, n2DAC respectively receive the driving signals Sdrv1, Sdrv2, Sdrv3, Sdrv4 from the level shifters p1LVSHT, n1LVSHT, p2LVSHT, n2LVSHT, convert the driving signals Sdrv1, Sdrv2, Sdrv3, Sdrv4 to the converted signals Scnv1, Scnv2, Scnv3, Scnv4, and transmit the converted signals Scnv1, Scnv2, Scnv3, Scnv4 to the channel setting module setMDL_m.
The channel setting module setMDL_m (60) includes a buffer 60a and a de-multiplexer switching circuit 60b. The buffer 60a includes operational amplifiers op1, op2, and the de-multiplexer switching circuit 60b includes de-mux switches sw11, sw22, sw13, sw33, sw24, sw44.
The operational amplifier op1 is electrically connected to the converting circuit p1DAC, and the operational amplifier op2 is electrically connected to the converting circuit n1DAC. The converting circuits p1DAC, n1DAC, p2DAC, n2DAC respectively generate the converted signals Scnv1, Scnv2, Scnv3, Scnv4. After receiving the converted signals Scnv1, the operational amplifier op1 amplifies the converted signal Scnv1 to generate the output voltage Sout1. After receiving the converted signals Scnv2, the operational amplifier op2 amplifies the converted signal Scnv2 to generate the output voltage Sout2.
In
Each of the auxiliary output channels corresponds to a first stage latch, a second stage latch, a level shifter, and a converting circuit. Therefore, the first stage latch L1a, the second stage latch L2c, the level shifter p2LVSHT, and the converting circuit p2DAC jointly form an auxiliary output channel, and the first stage latch L1b, the second stage latch L2d, the level shifter n2LVSHT, and the converting circuit n2DAC jointly form the other auxiliary output channel.
The internal components and their interconnections in the de-multiplexer switching circuit 60b are described. The de-mux switch sw11 is electrically connected to the operational amplifier op1 and the source line SLm1, and the de-mux switch sw22 is electrically connected to the operational amplifier op2 and the source line SLm2. The de-mux switch sw13 is electrically connected to the operational amplifier op1 and the source line SLm3, and the de-mux switch sw33 is electrically connected to the converting circuit p2DAC and the source line SLm3. The de-mux switch sw24 is electrically connected to the operational amplifier op2 and the source line SLm4, and the de-mux switch sw44 is electrically connected to the converting circuit n2DAC and the source line SLm4. In the de-multiplexer switching circuit 60b, the de-mux switches sw11, sw13 are related to the main output channel corresponding to the operational amplifier op1, the de-mux switches sw22, sw24 are related to the main output channel corresponding to the operational amplifier op2, the switch sw33 is related to the auxiliary output channel corresponding to the converting circuit p2DAC, and the switch sw44 is related to the auxiliary output channel corresponding to the converting circuit n2DAC.
The pixels, which are disposed at the y-th row and corresponding to the channel setting module setMDL_m, are shown. The pixels pxlm1y, pxlm2y, pxlm3y, pxlm4y are jointly electrically connected to the gate line GL[y], and the pixels pxlm1y, pxlm2y, pxlm3y, pxlm4y are respectively electrically connected to the source lines SLm1, SLm2, SLm3, SLm4.
In
The source lines (SLm1, SLm2, SLm3, SLm4) in
The first stage latch L1a is corresponding to a main output channel and an auxiliary output channel, and the first stage latch L1b is corresponding to the other main output channel and the other auxiliary output channel. The corresponding main output channel and the auxiliary output channel have similar components, except that the auxiliary output channel excludes an operational amplifier.
The state of the channel setting module setMDL_m in
The state of the channel setting module setMDL_m in
In
According to the third embodiment, two loading signals LD1, LD2 are adopted. The loading signal LD1 maintains at the on-level between time point t3 and time point t4, and the loading signal LD2 maintains at the on-level between time point t6 and time point t7. That is, two loading pulses are generated.
After receiving the loading pulse of the loading signal LD1, the channel setting module setMDL_m starts to enter the de-multiplexed duration Tdmux1 at time point t4. During the de-multiplexed duration Tdmux1, the second stage latches L2a, L2c simultaneously acquire the pre-data Spre1 from the first stage latch L1a, and the second stage latches L2b, L2d simultaneously acquire the pre-data Spre2 from the first stage latch L1b. Then, the second stage latches L2a, L2b, L2c, L2d respectively generate the latched data Slat1, Slat2, Slat3, Slat4, and the level shifters p1LVSHT, n1LVSHT, p2LVSHT, n2LVSHT respectively generate the driving signals Sdrv1, Sdrv2, Sdrv3, Sdrv4. The converting circuits p1DAC, n1DAC generate the converted signals Scnv1, Scnv2, and the operational amplifiers op1, op2 start to amplify the converted signals Scnv1, Scnv2 to generate the output voltages Sout1, Sout2 accordingly. Please note that the converted signals Scnv3, Scnv4 are not amplified by any of the operational amplifiers op1, op2.
In the de-multiplexed duration Tdmux1, the origins and generation paths of the converted signals Scnv1, Scnv3 are similar, so as the origins and generation paths of the converted signals Scnv2, Scnv4. Both the converted signals Scnv1, Scnv3 are generated based on the pre-data Spre1, with further processing of a second stage latch (L2a/L2c), a level shifter (p1LVSHT/p2LVSHT), and a converting circuit (p1DAC/p2DAC). Both the converted signals Scnv2, Scnv4 are generated based on the pre-data Spre2, with further processing of a second stage latch (L2b/L2d), a level shifter (n1LVSHT/n2LVSHT), and a converting circuit (n1DAC/n2DAC).
After receiving the loading pulse of the loading signal LD2, the channel setting module setMDL_m starts to enter the de-multiplexed duration Tdmux2 at time point t8. During the de-multiplexed duration Tdmux2, the second stage latches L2a, L2b respectively acquires the pre-data Spre1, Spre2 from the first stage latches L1a, L2b. Then, the second stage latches L2a, L2b respectively generate the latched data Slat1, Slat2, and the level shifters p1LVSHT, n1LVSHT respectively generate the driving signals Sdrv1, Sdrv2. The converting circuits p1DAC, n1DAC generate the converted signals Scnv1, Scnv2, and the operational amplifiers op1, op2 start to amplify the converted signals Scnv1, Scnv2 to generate the output voltages Sout1, Sout2 accordingly. Please note that the second stage latches L2c, L2d, the level shifters p2LVSHT, n2LVSHT, and the converting circuits p2DAC, n2DAC do not operate in response to the loading pulse of the loading signal LD2. Consequentially, the converted signals Scnv3, Scnv4 are not updated during the de-multiplexed duration Tdmux2.
In the third embodiment, the video signals received by the first stage latches L1a, L1b are corresponding to different pixels, depending on the de-multiplexed durations Tdmux1, Tdmux2. In the de-multiplexed duration Tdmux1, the first stage latches L1a, L1b receive the video signals corresponding to the pixels pxlm3y, pxlm4y, respectively. In the de-multiplexed duration Tdmux2, the first stage latches L1a, L1b receive the video signals corresponding to the pixels pxlm1y, pxlm2y, respectively.
At time point t4, the switch-setting signals Ssw13, Ssw24 transit from the off-level to the on-level. The switch-setting signals Ssw13, Ssw24 transit from the on-level to the off-level at time point t5. Therefore, between time point t4 and time point t5, the channel setting module is at the setting state STa (
Between time point t5 and time point t8 (the gap duration ΔTg), the channel setting module setMDL_m is at a transition state between the setting state STα and the setting state STβ. In the transition state, the de-mux switches sw13, sw24, sw11, sw22, sw33, sw44 are all turned off because the switch-setting signals Ssw13, Ssw24, Ssw11, Ssw22, Ssw33, Ssw44 are at the off-level. During the gap duration ΔTg, the potentials of the source lines SLm1, SLm2, SLm3, SLm4 remain unchanged.
At time point t8, the switch-setting signals Ssw11, Ssw22, Ssw33, Ssw44 transit from the off-level to the on-level. Therefore, between time point t8 and time point t10, the channel setting module is at the setting state STβ (
The dotted circle C3 shows that the source line SLm3 might have overshoot at the beginning of the de-multiplexed duration Tdmux2, as the biased source line SLm2 might cause coupling effects to the source lines SLm3. Due to the overshoot, the potential of the source lines SLm3 is slightly affected and rises to a value slightly higher than the pixel voltage Vm2y at and time point t8. Whereas, the potential of the source line SLm3 drops again and transits to the pixel voltage Vm3y because the de-mux switch sw33 is turned on, and the source line SLm3 starts to receive supplement charges from the converting circuit p2DAC.
In
When m≠M, the source line SLm4 has two adjacent source lines, including the source line SLm3 in the same channel setting module setMDL_m and another source line SLm1 in the neighboring channel setting module setMDL_(m+1). The source line SLm4 is thus affected by the first source line SLm1 in the (m+1)-th channel setting module setMDL_m, and an overshoot occurs after time point t8. Please note that when m≠M, the potential changes of the source line SLm4 should be similar to those of the source line SLm3.
As shown in
In the third embodiment, the de-multiplexed duration Tdmux1 is mainly used for providing output voltages Sout3, Sout4. Moreover, the de-multiplexed duration Tdmux2 is used for simultaneously providing output voltages Sout1, Sout2 to the source lines SLm1, SLm2, and compensating the side effect of the coupling at the source lines SLm3, SLm4 at the same time. The length of the de-multiplexed duration Tdmux1 is equivalent to the length of the de-multiplexed duration Tdmux2. The state-changing sequence of the channel setting module setMDL_m in the third embodiment is summarized in Table 5.
For the application of LCD panels, the polarity inversion function needs to be concerned. Therefore,
The channel setting module setMDL_m includes operational amplifiers op1, op2, and de-mux switches swp11, swn12, swp13, swdp23, swn24, swdn24, swp12, swn11, swp14, swdp24, swn13, swdn23. The de-mux switches swp11, swn12, swp13, swdp23, swn24, Swdn24, swp12, swn11, swp14, swdp24, swn13, swdn23 in
The de-mux switches show in solid lines (swp11, swn12, swp13, swdp23, swn24, swn24, swdn24) are selectively turned on when the polarity setting signal PL is at the on-level (PL=1), and all turned off when the polarity setting signal PL is at the off-level (PL=0). The de-mux switches shown in dotted lines (swp12, swn11, swp14, swdp24, swn13, swdn23) are all turned off when the polarity setting signal PL is at the on-level, and selectively turned on when the polarity setting signal PL is at the off-level.
The channel setting module setMDL_m in
The control of the channel setting module setMDL_m in
In practical applications, the number of operational amplifiers and the number of de-mux switches in the channel setting module setMDL_m should not be limited.
Please refer to
By utilizing the control methods described in the embodiments, the channel setting module setMDL_m is capable of depressing the side effects of coupling. In consequence, potentials of the floating source lines can be maintained as the desired pixel voltages by the time the potential of the gate line GL[y] is dropped to the off-level.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.
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