The disclosure relates to a light-emitting diode (LED) display device, and in particular, to a driver device of an LED display panel and an operation method thereof.
The transistor of a sub-pixel circuit of an organic light-emitting display (OLED) panel exhibits the diode property, such that the gate voltage of the transistor may experience voltage overcharging in the data scanning period. When voltage overcharging occurs in the gate voltage of the transistor of the sub-pixel circuit, the voltage of the storage capacitor of the sub-pixel circuit may not follow an output voltage of an output buffer to the target level, leading to abnormal display of the OLED panel.
It should be noted that the contents disclosed in the “Description of Related Art” section is used for enhancement of understanding of the disclosure. A part of the contents (or all of the contents) disclosed in the “Description of Related Art” section may not pertain to the conventional technology known to people having ordinary skill in the art. The information disclosed in the “Description of Related Art” section does not mean that the content is known to people having ordinary skill in the art before the filing of the disclosure.
The disclosure provides a driver device and an operation method thereof to prevent an overcharging phenomenon caused by an equalization operation.
In an embodiment of the disclosure, the driver device is adapted to drive a light-emitting diode display panel. The driver device includes a source driver circuit, an output switching circuit, and an equalization control circuit. A first input end and a second input end of the output switching circuit are respectively coupled to a first output end and a second output end of the source driver circuit. A first output end and a second output end of the output switching circuit are adapted to be coupled to a first data line and a second data line of the light-emitting diode display panel. The output switching circuit is capable of performing an equalization operation on the first data line and the second data line. The equalization control circuit is configured to check whether sub-pixel data of the first data line and sub-pixel data of the second data line meet a predetermined condition. The equalization control circuit determines whether to control the output switching circuit to perform the equalization operation on the first data line and the second data line in a data scanning period according to the checking result after a reset period. In the reset period, a plurality of sub-pixels of the light-emitting diode display panel located on a current display line of the light-emitting diode display panel are reset.
An operation method provided by an embodiment of the disclosure includes the following steps. An equalization operation is performed on a first data line and a second data line of a light-emitting diode display panel by an output switching circuit of a driver device. Whether sub-pixel data of the first data line and sub-pixel data of the second data line meet a predetermined condition is checked by an equalization control circuit of the driver device. A plurality of sub-pixels of the light-emitting diode display panel located on a current display line of the light-emitting diode display panel are reset in a reset period. Whether to control the output switching circuit to perform the equalization operation on the first data line and the second data line in a data scanning period according to the checking result after the reset period is determined by the equalization control circuit.
To sum up, in the driver device and the operation method thereof provided by the embodiments of the disclosure, the driver device may check whether the sub-pixel data of the first data line and the sub-pixel data of the second data line meet the predetermined condition, so as to further determine whether to perform the equalization operation on the first data line and the second data line according to the checking result. For instance, when the predetermined condition is met, the output switching circuit may perform the equalization operation to reduce the voltage swing caused by the charging and discharging operations performed on the data lines. When the predetermined condition is not met, the output switching circuit does not perform the equalization operation to prevent the overcharging phenomenon from occurring. Therefore, the driver device may prevent the overcharging phenomenon caused by the equalization operation from occurring.
To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows.
The term “coupled to (or connected to)” used in the entire disclosure (including claims) refers to any direct or indirect connecting means. For example, if the disclosure describes a first apparatus is coupled to (or connected to) a second apparatus, the description should be explained as the first apparatus that is connected directly to the second apparatus, or the first apparatus, through connecting other apparatus or using certain connecting means, is connected indirectly to the second apparatus. In addition, terms such as “first” and “second” in the entire specification (including claims) are used only to name the elements or to distinguish different embodiments or scopes and should not be construed as the upper limit or lower limit of the number of any element and should not be construed to limit the order of the elements. Moreover, elements/components/steps with the same reference numerals represent the same or similar parts in the figures and embodiments where appropriate. Descriptions of the elements/components/steps with the same reference numerals or terms in different embodiments may be references for one another.
Parasite capacitor on the data line of the OLED panel is considerably greater than the storage capacitor CST (approximately 100 to 200 times greater) generally. A decrease in voltage swing of charging and discharging operations performed on the data line may facilitate improvement of power consumption of the OLED panel. In any case, a charge-sharing operation applicable to a liquid crystal display (LCD) panel may not be easily transferred to the OLED panel. If the charge-sharing operation is unconditionally performed on the data line of the OLED panel, the storage capacitor CST of the sub-pixel circuit may experience voltage overcharging (excessive charging). Based on a structural property of sub-pixel circuit of the OLED panel, once voltage overcharging occurs in the storage capacitor CST, not until the storage capacitor CST is reset may a voltage of the storage capacitor CST be pulled back to a target level (a data voltage level corresponding to display data).
With reference to
In the data scanning period Pscan, the output buffer (not shown) of the DDIC may write the data voltage DATA corresponding to the display data to the storage capacitor CST. Nevertheless, as affected by a diode property of the transistor M3 connected in the form of a diode, the gate voltage Vg of the transistor M3 may experience voltage overcharging in the data scanning period Pscan. DATA1 shown in
In the following embodiments, an equalization operation of a light-emitting diode (LED) display panel is described. According to design needs, the LED display panel may be an organic light-emitting display (OLED) panel or other types of display panels. Based on a relationship between a previous line and a current line and a final value of a data line after data line EQ is completed, a driver device may determine whether to perform an equalization operation on an adjacent data line. The equalization operation refers to providing a short-circuit path between two data lines of the display panel, so that voltages of the two data lines temporarily become consistent. Generally, the time of the equalization operation is extremely short. After the equalization operation ends, the short-circuit path is cut off, and normal operation may thus be prevented from being affected. When a predetermined condition is met, the driver device may perform the equalization operation on the adjacent data line. In contrast, when the predetermined condition is not met, the driver device may not perform the equalization operation. As the equalization operation may be selectively performed, the driver device may not only reduce a voltage swing caused by charging and discharging operations performed on the data line but may also prevent an overcharging phenomenon caused by the equalization operation from occurring.
A first input end and a second input end of the output switching circuit 330 are respectively coupled to a first output end and a second output end of the source driver circuit 320. A first output end and a second output end of the output switching circuit 330 are adapted to be coupled to a first data line and a second data line of the OLED panel 10. The source driver circuit 320 may transmit the data voltage to the first data line and the second data line of the OLED panel 10 through the output switching circuit 330. In addition, the output switching circuit 330 may selectively perform the equalization operation on the first data line and the second data line of the OLED panel 10. The OLED panel 10 includes a plurality of display sub-pixels, and each of these display sub-pixels includes a storage capacitor (e.g., the storage capacitor CST shown in
The equalization control circuit 310 may check whether the sub-pixel data of the first data line and the sub-pixel data of the second data line meet the predetermined condition in the data scanning period (step S420). The predetermined condition may prevent the storage capacitors (e.g., the storage capacitor CST shown in
After the reset period, the equalization control circuit 310 may determine whether to control the output switching circuit to perform the equalization operation on the first data line and the second data line in the data scanning period according to the checking result (step S430). When the sub-pixel data of the first data line and the sub-pixel data of the second data line does not meet the predetermined condition (the determination result in step S430 is “no”), the driver device 300 performs step S450. When the sub-pixel data of the first data line and the sub-pixel data of the second data line meet the predetermined condition (the determination result in step S430 is “yes”), the driver device 300 performs step S440.
In step S440, based on control performed by the equalization control circuit 310, the output switching circuit 330 performs the equalization operation on the first data line and the second data line of the OLED panel 10. For instance, the output switching circuit 330 may set the first data line to be electrically connected to the second data line in step S440 and set the first data line not to be electrically connected to the second data line after step S440 ends. After step S440 ends, the driver device 300 performs step S450.
In step S450, the source driver circuit 320 may transmit the sub-pixel data (the data voltage) to the first data line and the second data line of the OLED panel 10 through the output switching circuit 330 to write the sub-pixel data into the sub-pixels on the current display line of the OLED panel 10. The emission period begins after the data scanning period. In the emission period, the driver device 300 sets the sub-pixels on the current display line of the OLED panel 10 to perform light emitting and displaying (that is, lighting up emission elements in the sub-pixels, step S460).
Based on the above, based on the checking result of “whether the sub-pixel data of the first data line and the sub-pixel data of the second data line of the OLED panel 10 meet the predetermined condition”, the driver device 300 provided by this embodiment may determine whether to perform the equalization operation on the first data line and the second data line. For instance, when the predetermined condition is met, the output switching circuit 330 may perform the equalization operation to reduce the voltage swing caused by the charging and discharging operations performed on the data lines. When the predetermined condition is not met, the output switching circuit 330 does not perform the equalization operation to prevent the overcharging phenomenon from occurring. Hence, the driver device 300 may prevent the overcharging phenomenon caused by the equalization operation from occurring. In particular, regarding a sub-pixel (e.g., the sub-pixel circuit shown in
The predetermined condition may be defined according to design needs. For instance, in some embodiments, the sub-pixel data of the first data line to be checked includes previous sub-pixel data and current sub-pixel data, and the sub-pixel data of the second data line to be checked includes previous sub-pixel data and current sub-pixel data. The predetermined condition may include a relationship among the four. The equalization control circuit 310 may check the previous sub-pixel data of the first data line, the current sub-pixel data of the first data line, the previous sub-pixel data of the second data line, and the current sub-pixel data of the second data line in step S420 to determine whether to control the output switching circuit 330 to perform the equalization operation on the first data line and the second data line. The output switching circuit 330 may perform the equalization operation on the first data line and the second data line in the data scanning period corresponding to the current display line of the OLED panel 10.
In some embodiments, the equalization control circuit 310 may check a changing direction of the sub-pixel data of the first data line and a changing direction of the sub-pixel data of the second data line (the predetermined condition) in step S420. For instance, in some embodiments, the predetermined condition includes a condition one and a condition two. The condition one is whether “a direction from a previous voltage level corresponding to the previous sub-pixel data of the first data line towards an equalized level of the first data line and the second data line” is consistent with “a direction from the previous voltage level corresponding to the previous sub-pixel data of the first data line towards a current voltage level corresponding to the current sub-pixel data of the first data line”. The condition two is whether “a direction from a previous voltage level corresponding to the previous sub-pixel data of the second data line towards the equalized level of the first data line and the second data line” is consistent with “a direction from the previous voltage level corresponding to the previous sub-pixel data of the second data line towards a current voltage level corresponding to the current sub-pixel data of the second data line”.
When the previous sub-pixel data of the first data line is greater than the previous sub-pixel data of the second data line, when the current sub-pixel data of the first data line is less than a mean of the previous sub-pixel data of the first data line and the previous sub-pixel data of the second data line, and when the current sub-pixel data of the second data line is greater than the mean, the equalization control circuit 310 may control the output switching circuit 330 to perform the equalization operation. When the previous sub-pixel data of the first data line is less than the previous sub-pixel data of the second data line, when the current sub-pixel data of the first data line is greater than the mean, and when the current sub-pixel data of the second data line is less than the mean, the equalization control circuit 310 may control the output switching circuit 330 to perform the equalization operation.
SEVEN[X][Y−1])/2 is a mean of the previous sub-pixel data SODD[X][Y−1] and the previous sub-pixel data SEVEN[X][Y−1].
When the current sub-pixel data of the first data line is less than the mean (i.e., SODD[X][Y]<(SODD[X][Y−1]+SEVEN[X][Y−1])/2) and when the current sub-pixel data of the second data line is greater than the mean (i.e., SEVEN[X][Y]>(SODD[X][Y−1]+SEVEN[X][Y−1])/2), the determination result in step S520 is “yes”, so that the driver device 300 performs step S530. In step S530, the equalization control circuit 310 may control the output switching circuit 330 to perform the equalization operation on the first data line and the second data line of the OLED panel 10. The equalization operation may set voltages of the first data line and the second data line to be equal to a voltage level corresponding to the mean (SODD[X][Y−1]+SEVEN[X][Y−1])/2). When the determination result in step S520 is “no”, the driver device 300 performs step S550. In step S550, the equalization control circuit 310 may control the output switching circuit 330 not to perform the equalization operation on the first data line and the second data line of the OLED panel 10.
When the previous sub-pixel data SODD[X][Y−1] is not greater than the previous sub-pixel data SEVEN[X][Y−1] (the determination result in step S510 is “no”), the driver device 300 performs step S540. In step S540, the equalization control circuit 310 may determine whether the previous sub-pixel data SODD[X][Y−1] of the first data line is less than the previous sub-pixel data SEVEN[X][Y−1] of the second data line. When the previous sub-pixel data SODD[X][Y−1] is not less than the previous sub-pixel data SEVEN[X][Y−1] (the determination result in step S540 is “no”), the driver device 300 performs step S550. In step S550, the equalization control circuit 310 may control the output switching circuit 330 not to perform the equalization operation on the first data line and the second data line of the OLED panel 10.
When the previous sub-pixel data SODD[X][Y−1] is less than the previous sub-pixel data SEVEN[X][Y−1] (the determination result in step S540 is “yes”), the driver device 300 performs step S560. In step S560, the equalization control circuit 310 may compare between SODD[X][Y] and (SODD[X][Y−1]+SEVEN[X][Y−1])/2 and compares between SEVEN[X][Y] and (SODD[X][Y−1]+SEVEN[X][Y−1])/2. When the current sub-pixel data of the first data line is greater than the mean (i.e., SODD[X][Y]>(SODD[X][Y−1]+SEVEN[X][Y−1])/2) and when the current sub-pixel data of the second data line is less than the mean (i.e., SEVEN[X][Y]<(SODD[X][Y−1]+SEVEN[X][Y−1])/2, the determination result in step S560 is “yes”, so that the driver device 300 performs step S570. In step S570, the equalization control circuit 310 may control the output switching circuit 330 to perform the equalization operation on the first data line and the second data line of the OLED panel 10. When the determination result in step S560 is “no”, the driver device 300 performs step S550. In step S550, the equalization control circuit 310 may control the output switching circuit 330 not to perform the equalization operation on the first data line and the second data line of the OLED panel 10.
Determination conditions of the equalization operation include determination of whether voltages of two adjacent data lines are different and consideration of whether an overcharging problem occurs in the data lines after the equalization operation ends. The determination of the difference between two adjacent data lines is to ensure that the equalization operation provides a power saving effect. Determining whether a voltage changing direction of two adjacent data lines in the equalization operation is consistent with a target voltage direction of the data line may prevent the problem of data line overcharging from occurring. Hence, the driver device 300 may ensure that a visual effect of the OLED panel 10 is not affected after the equalization operation is completed.
Based on the timing information provided by the digital control and timing generation circuit 340, the panel control signal generation circuit 350 may generate a scan start pulse STV, a scan clock signal SCK, an emission start pulse ETV, and an emission clock signal ECK to a gate driver 11. The gate driver 11 includes a plurality of driving channels, such as driving channels GN and GN-1 shown in
The equalization control circuit 310 shown in
The shift register 312 is coupled to the data and equalization control circuit 311 to receive the equalization control signal SEQ, the clock signal CLK, sub-pixel data DATA_O, and sub-pixel data DATA_E. The data latch 313 is coupled to the shift register 312 to receive the equalization control signal SEQ, the sub-pixel data DATA_O, and the sub-pixel data DATA_E. The data latch 313 is further coupled to the data and equalization control circuit 311 to receive a latch signal LOAD, an output enabling clock SOE_PRD, and an equalization clock EQ_PRD. The logic circuit 314 is coupled to the data latch 313 to receive an equalization control signal SEQ1. The logic circuit 314 is further coupled to the data and equalization control circuit 311 through the data latch 313 to receive the output enabling clock SOE_PRD and the equalization clock EQ_PRD.
The source driver circuit 320 includes a digital to analog converter (DAC) 321, a DAC 322, an output buffer 323, and an output buffer 324. According to design needs, the output buffer 323 and the output buffer 324 may be operational (OP) amplifiers or other gain circuits. An input end of the DAC 321 is coupled to a first output end of the data latch 313. An input end of the DAC 322 is coupled to a second output end of the data latch 313. An input end of the output buffer 323 is coupled to an output end of the DAC 321. An output end of the output buffer 323 is coupled to the output switching circuit 330. An input end of the output buffer 324 is coupled to an output end of the DAC 322. An output end of the output buffer 324 is coupled to the output switching circuit 330.
The logic circuit 314 generates switch signals SEQ1 and SOE1 according to the equalization control signal SEQ1, the output enabling clock SOE_PRD, and the equalization clock EQ_PRD to control the output switching circuit 330. The output switching circuit 330 shown in
When the equalization control circuit 310 determines to control the output switching circuit 330 to perform the equalization operation in the data scanning period Pscan[Y−1], the equalization control circuit 310 determines to control the output switch SWODD1 and the output switch SWEVEN1 to be turned off and the equalization switch SWEQ1 to be turned on in a first sub-period P1 of the data scanning period Pscan[Y−1]. Moreover, the equalization control circuit 310 determines to control the output switch SWODD1 and the output switch SWEVEN1 to be turned on and the equalization switch SWEQ1 to be turned off in a second sub-period P2 of the data scanning period Pscan[Y−1] after the first sub-period P1. For instance, when the equalization control signal SEQ1 is at a high logic level (representing that the equalization operation is determined to be performed), the logic circuit 314 turns off the output switch SWODD1 and the output switch SWEVEN1 and turns on the equalization switch SWEQ1 in the first sub-period P1 of the data scanning period Pscan[Y−1] and turns on the output switch SWODD1 and the output switch SWEVEN1 and turns off the equalization switch SWEQ1 in the second sub-period P2 of the data scanning period Pscan[Y−1].
When the equalization control circuit 310 determines not to control the output switching circuit 330 to perform the equalization operation in the data scanning period Pscan[Y−1], the equalization control circuit 310 continuously turns off the equalization switch SWEQ1 in the data scanning period Pscan[Y−1]. For instance, when the equalization control signal SEQ1 is at a low logic level (representing that the equalization operation is determined not to be performed), the logic circuit 314 may continuously turns on the output switch SWODD1 and the output switch SWEVEN1 and continuously turns off the equalization switch SWEQ1 in the data scanning period Pscan[Y−1].
In the embodiment shown in
The equalization control circuit 310 shown in
The shift register 316 is coupled to the data and equalization control circuit 315 to receive the equalization control signal SEQ_O, the equalization control signal SEQ_E, the clock signal CLK, and the sub-pixel data DATA_O/E. The data latch 317 is coupled to the shift register 316 to receive the equalization control signal SEQ_O, the equalization control signal SEQ_E, and the sub-pixel data DATA_O/E. The data latch 317 is further coupled to the data and equalization control circuit 315 to receive the latch signal LOAD, the output enabling clock SOE1_PRD, the output enabling clock SOE2_PRD, the equalization clock EQ1_PRD, and the equalization clock EQ2_PRD.
The source driver circuit 320 includes a DAC 321, a DAC 322, an output buffer 323, and an output buffer 324. Description of the DAC 321, DAC 322, the output buffer 323, and the output buffer 324 shown in
The logic circuit 318 generates switch signals SEQODD1 and SOEODD1 according to the equalization control signal SEQ_O1, the equalization control signal SEQ_E1, the output enabling clock SOE1_PRD, the output enabling clock SOE2_PRD, the equalization clock EQ1_PRD, and the equalization clock EQ2_PRD to control the output switching circuit 330. The output switching circuit 330 shown in
The gate driver 11 includes a plurality of driving channels. The gate driver 11 may generate a reset signal INIT (e.g., a reset signal INITODD[N] of a Nth odd reset line and a reset signal INITEVEN[N] of a Nth even reset line), a scan signal SCAN (e.g., a scan line SCANODD[N] of a Nth odd display line and a scan signal SCANEVEN[N] of a Nth even display line), and an emission signal EMI (e.g., an emission signal EMIODD[N] of a Nth odd emission line and an emission signal EMIEVEN[N] of a Nth even emission line) to the sub-pixels of the OLED panel 10. According to design needs, in some embodiments, description of the sub-pixels of the OLED panel 10 shown in
The equalization control circuit 310 shown in
The shift register 316 is coupled to the data and equalization control circuit 319 to receive the equalization control signal SEQ, the clock signal CLK, sub-pixel data DATA_O, and sub-pixel data DATA_E. The data latch 317 is coupled to the shift register 316 to receive the equalization control signal SEQ, the sub-pixel data DATA_O, and the sub-pixel data DATA_E. The data latch 317 is further coupled to the data and equalization control circuit 319 to receive the latch signal LOAD, the output enabling clock SOE1_PRD, the output enabling clock SOE2_PRD, the equalization clock EQ1_PRD, and the equalization clock EQ2_PRD.
The source driver circuit 320 shown in
The logic circuit 318 generates switch signals SEQODD1 and SOEODD1 according to the equalization control signal SEQ1, the output enabling clock SOE1_PRD, the output enabling clock SOE2_PRD, the equalization clock EQ1_PRD, and the equalization clock EQ2_PRD to control the output switching circuit 330. The output switching circuit 330 shown in
In the embodiment shown in
In the embodiments shown by
According to different design needs, the equalization control circuit 310, the data and equalization control circuit 311, and/or the digital control and timing generation circuit 340 may be implemented in the form of hardware, firmware, software (i.e., a program), or a combination of the majority of the foregoing three.
In the form of hardware, the blocks of the equalization control circuit 310, the data and equalization control circuit 311, and/or the digital control and timing generation circuit 340 may be implemented in the form of a logic circuit on an integrated circuit. Related functions of the equalization control circuit 310, the data and equalization control circuit 311, and/or the digital control and timing generation circuit 340 may be implemented as hardware through using hardware description languages (e.g., Verilog HDL or VHDL) or other suitable programming languages. For instance, the related functions of the equalization control circuit 310, the data and equalization control circuit 311, and/or the digital control and timing generation circuit 340 may be implemented in one or a plurality of controllers, a micro controller, a micro processor, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), and/or various logic blocks, modules, and circuits in other processing units.
In the form of software and/or firmware, the related functions of the equalization control circuit 310, the data and equalization control circuit 311, and/or the digital control and timing generation circuit 340 may be implemented as programming codes. For instance, the equalization control circuit 310, the data and equalization control circuit 311, and/or the digital control and timing generation circuit 340 may be implemented by using a general programming language (e.g., C, C++, or an assembly language) or other suitable programming languages. The programming code may be recorded/stored in a recording medium. In some embodiments, the recording medium includes, for example, read only memory (ROM), random access memory (RAM), and/or a storage device. The storage device includes a hard disk drive (HDD) a solid-state drive (SSD), or other storage devices. In some other embodiments, the recording medium may include a “non-transitory computer readable medium”. For instance, a tape, a disk, a card, semiconductor memory, a programmable logic circuit, etc. may be used to be implemented as the non-transitory computer readable medium. A controller, a micro controller, or a micro processor may read and execute the programming code from the recording medium to accomplish the related functions of the equalization control circuit 310, the data and equalization control circuit 311, and/or the digital control and timing generation circuit 340.
In view of the foregoing, in the embodiments, the driver device 300 may check whether the sub-pixel data of the first data line and the sub-pixel data of the second data line meet the predetermined condition, so as to further determine whether to perform the equalization operation on the first data line and the second data line according to the checking result. For instance, when the predetermined condition is met, the output switching circuit 330 may perform the equalization operation to reduce the voltage swing caused by the charging and discharging operations performed on the data lines. When the predetermined condition is not met, the output switching circuit 330 does not perform the equalization operation to prevent the overcharging phenomenon from occurring. Hence, the driver device 300 may prevent the overcharging phenomenon caused by the equalization operation from occurring.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.
This application claims the priority benefit of U.S. provisional applications Ser. No. 63/027,356, filed on May 20, 2020. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
Number | Date | Country | |
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63027356 | May 2020 | US |