CN213904905U - Common electrode discharge unit of display array and liquid crystal display device - Google Patents
Common electrode discharge unit of display array and liquid crystal display device Download PDFInfo
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- CN213904905U CN213904905U CN202023279948.5U CN202023279948U CN213904905U CN 213904905 U CN213904905 U CN 213904905U CN 202023279948 U CN202023279948 U CN 202023279948U CN 213904905 U CN213904905 U CN 213904905U
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Abstract
The utility model discloses a display array's common electrode discharge unit and liquid crystal display device, include: the comparator has a non-inverting input end for receiving the threshold voltage, an inverting input end for receiving the shutdown control signal, a positive power supply end for receiving the backlight output signal, and a negative power supply end grounded; the first end of the first resistor is connected with the output end of the comparator; the control end of the discharge circuit is connected with the second end of the first resistor, the first end of the discharge circuit is connected with the common electrode of the display array, and the second end of the discharge circuit is grounded; when the low level was received to discharge circuit's control end, discharge circuit turned off the current path between common electrode and the ground, the utility model provides a display array's common electrode discharge unit and liquid crystal display device can accelerate the speed of discharging of display array's common electrode when shutting down to effectively improve shutdown ghost phenomenon.
Description
Technical Field
The utility model relates to a display device technical field, in particular to display array's common electrode discharge unit and liquid crystal display device.
Background
A Liquid Crystal Display (LCD) is a Display device that changes the light transmittance of a light source by utilizing the phenomenon that the alignment direction of Liquid Crystal molecules changes under the action of an electric field. Due to the advantages of good display quality, small size and low power consumption, liquid crystal display devices have been widely used in electronic devices such as high definition digital televisions, desktop computers, notebook computers, tablet computers, mobile phones, digital cameras, and the like.
The liquid crystal display device includes a display array, a driving circuit, and a backlight unit. The display array comprises a plurality of grid scanning lines and a plurality of source data lines which are intersected with each other, a pixel unit is formed at the intersection position of the grid scanning lines and the source data lines, and each pixel unit at least comprises a Thin Film Transistor (TFT). The driving circuit comprises a gate driving unit and a source driving unit, wherein in each frame period, the gate driving unit sequentially scans a plurality of gate scanning lines, the thin film transistors are gated through the gate scanning lines, then the source driving unit applies voltages corresponding to gray scales to the pixel units through the source data lines, so that the orientation of liquid crystal molecules is changed, and the light transmittance of the pixel units is correspondingly changed due to the orientation change of the liquid crystal molecules. The backlight unit is used for generating backlight and includes a plurality of LEDs (Light Emitting diodes) as Light Emitting sources.
Fig. 1 shows a schematic configuration diagram of a related art liquid crystal display device. The liquid crystal display device 100 includes a display array 110, a timing controller 120, a gate driving unit 130, a source driving unit 140, and a power unit 150.
Referring to fig. 2, fig. 2 shows a circuit schematic of a pixel cell of the display array of fig. 1. The display array 110 includes a plurality of pixel units 111 arranged in an array, and each pixel unit 111 mainly includes a thin film transistor T, a storage capacitor CS, a liquid crystal capacitor CLC, and a common electrode VCOM. Each pixel unit 111 is connected to the gate driving unit 130 through a gate line and connected to the source driving unit 140 through a source line. In response to a gate driving signal supplied through the gate line, the pixel unit 111 may receive a data signal through the data line, store the data signal in the storage capacitor, and control light emitted from a backlight unit (not shown) corresponding to the data signal, thereby displaying luminance corresponding to the data signal.
The timing controller 120 is used to control the gate driving unit 130 and the source driving unit 140. The timing controller 120 may receive an externally provided control signal (e.g., a control signal including a clock signal), and generate a gate control signal and a data control signal based on the control signal.
The gate driving unit 130 is connected to the timing controller 120, receives the gate control signal from the timing controller 120, generates a gate driving signal based on the gate control signal, and supplies the gate driving signal to a corresponding gate line.
The source driving unit 140 is connected to the timing controller 120, receives the source control signal and the frame data from the timing controller 140, generates a data signal corresponding to the frame data, and supplies the data signal to the corresponding data line.
The power unit 150 is connected to the timing controller 120 to generate a shutdown control signal XON, and the gate driving unit 130 is controlled to increase the voltage of the gate terminal of the thin film transistor T, so that the thin film transistor T is completely turned on, and the residual charges in the liquid crystal capacitor CLC can be rapidly discharged by the turned-on thin film transistor T and the data line electrically connected to the thin film transistor T, thereby shortening the complete discharge time of the residual charges and eliminating the shutdown afterimage to a certain extent.
When the pixel unit 111 is selected from the amorphous silicon thin film transistor, the common electrode VCOM is naturally powered off after the liquid crystal display device 100 is turned off, and the shutdown ghost phenomenon does not occur. However, when the pixel unit 111 is selected from an Oxide-derived thin film transistor, such as an IGZO (Indium Gallium Zinc Oxide) thin film transistor, if the common electrode VCOM discharges slowly, the shutdown ghost phenomenon may be more serious. Some of the power cells have a function of discharging the common electrode VCOM, but most of the power cells do not have the function, which results in higher development cost of the liquid crystal display device of the oxide-derived thin film transistor, and also reduces the selection range of the power cells.
SUMMERY OF THE UTILITY MODEL
In view of the above problems, an object of the present invention is to provide a common electrode discharge unit of a display array, which accelerates the discharge speed of the common electrode of the display array when a liquid crystal display device is turned off, thereby effectively improving the image sticking phenomenon when the liquid crystal display device is turned off.
According to an aspect of the present invention, there is provided a common electrode discharge unit of a display array, wherein, including: the comparator is characterized in that a non-inverting input end of the comparator receives a threshold voltage, an inverting input end of the comparator receives a shutdown control signal, a positive power supply end receives a backlight output signal, and a negative power supply end is grounded; a first resistor, a first end of the first resistor being connected to an output end of the comparator; and a control end of the discharge circuit is connected with a second end of the first resistor, a first end of the discharge circuit is connected with a common electrode of the display array, and a second end of the discharge circuit is grounded, wherein when the control end of the discharge circuit receives a high level, the discharge circuit conducts a current path between the common electrode and the ground, and when the control end receives a low level, the discharge circuit shuts off the current path between the common electrode and the ground.
Optionally, the discharge circuit comprises: a fourth resistor, a first end of the fourth resistor being connected to the common electrode; and the control end of the third switching tube is connected with the second end of the first resistor, the first end of the third switching tube is connected with the second end of the fourth resistor, and the second end of the third switching tube is grounded.
Optionally, the common electrode discharge unit of the display array further includes, connected between the second terminal of the first resistor and the control terminal of the third switching tube: the control end of the first switch tube is connected with the second end of the first resistor, and the second end of the first switch tube is grounded; a first end of the second resistor is connected with a positive power supply end of the comparator, and a second end of the second resistor is connected with an output end of the comparator; a first end of the third resistor is connected with a first end of the second resistor, and a second end of the third resistor is connected with a first end of the first switch tube; a control end of the second switching tube is connected with a second end of the third resistor, a first end of the second switching tube is connected with a first end of the third resistor, a second end of the second switching tube is connected with a control end of the third switching tube, and the first end of the second switching tube receives the backlight output signal; the timer is connected with the second switching tube, receives the power-off control signal and the backlight input signal, and generates the backlight output signal according to the power-off control signal and the backlight input signal; and a first end of the fifth resistor is connected with the second switch tube, and a second end of the fifth resistor is grounded.
Optionally, the timer is configured to output the backlight output signal as a high level when the shutdown control signal is inverted from a high level to a low level, and output the backlight output signal as a low level after a delay of a first predetermined time, wherein a voltage value of the backlight output signal at the high level is equal to a voltage value of the backlight input signal.
Optionally, the length of the first predetermined time of the timer may be set by a code.
Optionally, the common electrode discharge unit of the display array further includes a D flip-flop connected between the second end of the second switch tube and the control end of the discharge circuit, a data input end of the D flip-flop is connected to the second end of the second switch tube, a temporary storage data output end is connected to the control end of the third switch tube, and a clock pulse input end of the D flip-flop receives a gate turn-off signal.
Optionally, when the device is turned off, the gate turn-off signal is turned from a low level to a high level.
Optionally, after a second predetermined time when the shutdown control signal is inverted from the high level to the low level, the gate turn-off signal is inverted from the low level to the high level.
According to the utility model discloses an on the other hand still provides a liquid crystal display device, include: the display device comprises a display array, a grid driving unit for providing grid driving signals for the display array, a source driving unit for providing source signals for the display array, a time schedule controller for controlling the grid driving unit and the source driving unit, and a power unit, wherein the power unit is connected with the time schedule controller and provides shutdown control signals for the time schedule controller when the power unit is shut down; the display device is characterized by further comprising the common electrode discharging unit, wherein the common electrode discharging unit is connected with the power unit and the display array, receives the shutdown control signal and the threshold voltage, and discharges the common electrode of the display array according to the shutdown control signal and the threshold voltage.
Optionally, the display array comprises oxide thin film transistors.
The utility model provides a public electrode of display array discharge unit is with public electrode ground connection when shutting down for public electrode's the speed of discharging to effectively improve liquid crystal display device's shutdown ghost phenomenon.
Furthermore, the common electrode discharge unit of the display array further comprises a timer, and only when the liquid crystal display device is turned off and the power-off control signal is switched to the low level, the backlight output signal of the timer is switched to the high level, so that the common electrode discharge unit normally works, and the power consumption of the common electrode discharge unit is reduced.
Furthermore, after the timer delays for the first preset time, the backlight output signal is switched to the low level again, the third switching tube is turned off, and the connection between the common electrode and the ground is disconnected, so that the phenomenon that the common electrode of the display array is always grounded due to voltage fluctuation of a shutdown control signal and false operation of a common electrode discharge unit, and the phenomenon of locking due to false operation is avoided, the stability of the liquid crystal display device is effectively improved, and meanwhile, the power consumption is further reduced.
Furthermore, the common electrode discharge unit of the display array further comprises a D trigger, when the liquid crystal display device is shut down, the grid electrode closing signal is switched from low level to high level, the temporary storage data output end Q of the D trigger outputs high level, if the voltage value of the shutdown control signal fluctuates, the comparator and the timer work, the data input end of the D trigger receives the high level, the data output end of the D trigger still maintains the low level because the grid electrode closing signal is not switched from the low level to the high level, the third switch tube is turned off, the common electrode is not grounded, false operation of the common electrode discharge unit caused by voltage fluctuation of the shutdown control signal is avoided, and the stability of the liquid crystal display device is effectively improved.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:
fig. 1 is a schematic view showing a structure of a related art liquid crystal display device;
FIG. 2 shows a circuit schematic of a pixel cell of the display array of FIG. 1;
fig. 3 is a schematic structural diagram of a liquid crystal display device according to an embodiment of the present invention;
fig. 4 shows a common electrode discharge cell of a display array of a first embodiment of the present invention;
fig. 5 shows a common electrode discharge cell of a display array of a second embodiment of the present invention;
FIG. 6 is a schematic diagram of the timer of FIG. 5;
fig. 7 shows a common electrode discharge cell of a display array of a third embodiment of the present invention;
fig. 8 is a timing chart showing shutdown of the liquid crystal display device according to the embodiment of the present invention;
fig. 9 is a flowchart illustrating the operation of the liquid crystal display device according to the embodiment of the present invention when the liquid crystal display device is turned off.
Detailed Description
Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In the various figures, the same elements or modules are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale.
It should be understood that in the following description, "circuitry" may comprise singly or in combination hardware circuitry, programmable circuitry, state machine circuitry, and/or elements capable of storing instructions executed by programmable circuitry. When an element or circuit is referred to as being "connected to" another element or circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.
Also, certain terms are used throughout the description and claims to refer to particular components. As one of ordinary skill in the art will appreciate, manufacturers may refer to a component by different names. This patent specification and claims do not intend to distinguish between components that differ in name but not function.
Moreover, it is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In the present application, the switching transistor is a transistor operating in a switching mode to provide a current path, and includes one selected from a bipolar transistor or a field effect transistor. The first end and the second end of the switching tube are respectively a high potential end and a low potential end on a current path, and the control end is used for receiving a driving signal to control the switching tube to be switched on and off. A MOSFET (Metal-Oxide-semiconductor field-Effect Transistor) includes a first terminal, a second terminal, and a control terminal, and a current flows from the first terminal to the second terminal in an on state of the MOSFET. The first end, the second end and the control end of the P-type MOSFET are respectively a source electrode, a drain electrode and a grid electrode, and the first end, the second end and the control end of the N-type MOSFET are respectively a drain electrode, a source electrode and a grid electrode.
Fig. 3 is a schematic structural diagram of a liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device 200 includes a display array 210, a timing controller 220, a gate driving unit 230, a source driving unit 240, a power unit 250, and a common electrode discharging unit 260.
The display array 210 includes a plurality of pixel units arranged in an array, and each pixel unit mainly includes a thin film transistor, a storage capacitor, a liquid crystal capacitor, and a common electrode. Each pixel unit is connected to the gate driving unit 230 through a gate line and connected to the source driving unit 240 through a source line. In response to a gate driving signal supplied through the gate line, the pixel unit may receive a data signal through the data line, store the data signal in the storage capacitor, and control light emitted from a backlight unit (not shown) corresponding to the data signal, thereby displaying luminance corresponding to the data signal.
Specifically, the thin film transistor in the present embodiment is an Oxide thin film transistor, such as an IGZO (Indium Gallium Zinc Oxide) thin film transistor.
The timing controller 220 is used to control the gate driving unit 230 and the source driving unit 240. The timing controller 220 may receive an externally provided control signal (e.g., a control signal including a clock signal), and generate a gate control signal and a data control signal based on the control signal.
The gate driving unit 230 is connected to the timing controller 220, receives the gate control signal from the timing controller 220, generates a gate driving signal based on the gate control signal, and supplies the gate driving signal to a corresponding gate line.
The source driving unit 240 is connected to the timing controller 220, receives the source control signal and the frame data from the timing controller 240, generates a data signal corresponding to the frame data, and supplies the data signal to the corresponding data line.
The power unit 250 is connected to the timing controller 220 to generate a shutdown control signal XON, so that the tft is turned on completely by increasing the voltage at the gate terminal of the tft, and the residual charges in the liquid crystal capacitor can be discharged quickly by the tft in the on state and the data line electrically connected to the tft, thereby shortening the complete discharge time of the residual charges and eliminating the shutdown ghost to a certain extent.
The common electrode discharging unit 260 is connected to the display array 210 and the power unit 250, receives the shutdown control signal XON and the threshold voltage VREF, and discharges the common electrode Vcon of the display array 210 according to the received shutdown control signal XON and the threshold voltage VREF.
When the liquid crystal display device 200 normally operates, the voltage value of the shutdown control signal XON is greater than the threshold voltage VREF, and the common electrode discharge unit 260 does not operate.
When the liquid crystal display device 200 is turned off, the voltage value of the turn-off control signal XON decreases, and when the voltage value is smaller than the threshold voltage VREF, the common electrode discharging unit 260 grounds the common electrode VCOM, thereby accelerating the discharging speed of the common electrode VCOM, and effectively improving the turn-off ghost phenomenon of the liquid crystal display device.
Fig. 4 shows a common electrode discharge cell of a display array according to a first embodiment of the present invention.
The common electrode discharge unit 260 includes a comparator 261, a first resistor R1, and a discharge circuit 262.
The non-inverting input terminal of the comparator 261 receives the threshold voltage VREF, the inverting input terminal receives the shutdown control signal XON, the positive power terminal receives the backlight output signal VLED _ OUT, the negative power terminal is grounded, and the output terminal is connected to the first terminal of the first resistor R1.
The control terminal of the discharge circuit 262 is connected to the second terminal of the first resistor R1, the first terminal is connected to the common electrode VCOM of the display array 210, and the second terminal is grounded. When the control terminal of the discharge circuit 262 receives a high level, the discharge circuit 262 turns on the current path between the common electrode VCOM and the ground, and when the control terminal receives a low level, the discharge circuit 262 turns off the current path between the common electrode VCOM and the ground.
The discharge circuit 262 includes a fourth resistor R4 and a third switching tube Q3. A control terminal of the third switching tube Q2 is connected to the second terminal of the first resistor R1, a first terminal of the third switching tube Q3 is connected to the second terminal of the fourth resistor R4, a first terminal of the fourth resistor R4 is connected to the common electrode VCOM, and a second terminal of the third switching tube Q3 is grounded.
When the liquid crystal display device 200 normally operates, the shutdown control signal XON is at a high level, which is greater than the threshold voltage VREF, the output terminal of the comparator 261 outputs a low level, the third switching transistor Q3 is turned off, and the common electrode VCOM is not grounded.
When the liquid crystal display device 200 is turned off, the shutdown control signal XON is switched to the low level, and when the voltage value of the shutdown control signal XON is smaller than the threshold voltage VREF, the comparator 261 outputs the high level, the third switching tube Q3 is turned on, and the common electrode VCOM is grounded, so that the discharge speed of the common electrode VCOM is increased, and the shutdown ghost phenomenon of the liquid crystal display device is effectively improved.
Fig. 5 shows a common electrode discharge cell of a display array according to a second embodiment of the present invention.
The common electrode discharge unit 360 includes a comparator 361, a timer 362, a discharge circuit 363, a first resistor R1, a second resistor R2, a third resistor R3, a fifth resistor R5, a first switch tube Q1, and a second switch tube Q2.
The non-inverting input terminal of the comparator 361 receives the threshold voltage VREF, the inverting input terminal receives the shutdown control signal XON, the positive power terminal is connected to the first terminal of the second resistor R2, the negative power terminal is grounded, and the output terminal is connected to the first terminal of the first resistor R1 and the second terminal of the second resistor R2.
The first pin of the timer 362 is grounded, the fourth pin receives the input voltage VIN, the second pin receives the shutdown control signal XON, the third pin receives the backlight input signal VLED _ IN, the fifth pin is connected to the first end of the second resistor R2, and the first end of the second resistor R2 is further connected to the first end of the third resistor R3.
The control end of the first switch tube Q1 is connected to the second end of the first resistor R1, the first end of the first switch tube Q1 is connected to the second end of the third resistor R3, and the second end of the first switch tube Q1 is grounded.
The control end of the second switch tube Q2 is connected to the second end of the third resistor R3, the first end of the second switch tube Q2 is connected to the fifth pin of the timer 362, the second end of the second switch tube Q2 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 is grounded.
The control terminal of the discharge circuit 363 is connected to the first terminal of the fifth resistor R5, the first terminal is connected to the common electrode VCOM of the display array 210, and the second terminal is grounded. When the control terminal of the discharge circuit 363 receives a high level, the discharge circuit 363 turns on the current path between the common electrode VCOM and the ground, and when the control terminal receives a low level, the discharge circuit 363 turns off the current path between the common electrode VCOM and the ground.
The discharge circuit 363 includes a fourth resistor R4 and a third switching tube Q3. A control terminal of the third switching tube Q3 is connected to the second terminal of the first resistor R1, a control terminal of the third switching tube Q3 is connected to the first terminal of the fifth resistor R5, a first terminal of the third switching tube Q3 is connected to the second terminal of the fourth resistor R4, a first terminal of the fourth resistor R4 is connected to the common electrode VCOM, and a second terminal of the third switching tube Q3 is grounded.
Referring to fig. 6, fig. 6 shows a schematic diagram of the timer in fig. 5. The first pin of the timer 361 is grounded, the second pin receives the shutdown control signal XON, the third pin receives the backlight input signal VLED _ IN, the fourth pin receives the operating voltage VIN, and the fifth pin outputs the backlight output signal VLED _ OUT.
The shutdown control signal XON is at a high level, and the fifth pin of the timer 362 outputs a low level, i.e., the backlight output signal VLED _ OUT is at a low level.
The shutdown control signal XON is at a low level, and the fifth pin of the timer 362 outputs a high level, that is, the backlight output signal VLED _ OUT is at a high level, and has the same voltage value as the backlight input signal VLED _ IN.
Wherein the length of the first predetermined time may be set by a code.
When the liquid crystal display device 200 normally operates, the shutdown control signal XON is at a high level, the fifth pin of the timer 362 outputs a low level, that is, the backlight output signal VLED _ OUT is at a low level, the common electrode discharging unit 360 does not operate, the first switch Q1 and the second switch Q2 are turned off, the first end of the fifth resistor R5 is at a low level, the third switch Q3 is turned off, and the common electrode VCOM is not grounded.
When the lcd device 200 is turned off, the turn-off control signal XON is at a low level, the fifth pin of the timer 362 outputs a high level, that is, the backlight output signal VLED _ OUT is at a high level, and the common electrode discharge unit 360 operates.
At this time, the shutdown control signal XON is smaller than the threshold voltage VREF, the output terminal of the comparator 361 outputs a high level, the first switch tube Q1 is turned on, the control terminal of the second switch tube Q2 is grounded, because the backlight output signal VLED _ OUT is a high level at this time, the second switch tube Q2 is turned on, the control terminal of the third switch tube Q3 is a high level, the third switch tube Q3 is turned on, and the common electrode VCOM is grounded, thereby accelerating the discharge speed of the common electrode VCOM, and effectively improving the shutdown ghost phenomenon of the liquid crystal display device 200.
After the time delay of the first predetermined time, the backlight output signal VLED _ OUT switches to the low level, the comparator 361 stops working, the first switch Q1, the second switch Q2 and the third switch Q3 are turned off, and the common electrode VCOM is disconnected from the ground.
The utility model discloses the common electrode discharge unit 360 of second embodiment is with common electrode VCOM ground connection when shutting down for common electrode VCOM's the discharge rate to effectively improve liquid crystal display device 200's shutdown ghost phenomenon.
Further, only when the liquid crystal display device 200 is turned off and the power-off control signal XON is switched to the low level, the backlight output signal VLED _ OUT is switched to the high level, so that the common electrode discharging unit 460 works normally, and the power consumption of the common electrode discharging unit 460 is reduced.
Further, after the time delay of the timer 362 for the first predetermined time, the backlight output signal VLED _ OUT is switched to the low level again, the third switching tube Q3 is turned off, and the connection between the common electrode VCOM and the ground is disconnected, so that the common electrode of the display array 210 is always grounded due to the voltage value fluctuation of the shutdown control signal XON and the false operation of the common electrode discharge unit 360, and the locking phenomenon caused by the false operation occurs, thereby effectively improving the stability of the liquid crystal display device 200.
Fig. 7 shows a common electrode discharge cell of a display array according to a third embodiment of the present invention.
The common electrode discharge unit 460 includes a comparator 461, a timer 462, a D flip-flop 463, a discharge circuit 464, a first resistor R1, a second resistor R2, a third resistor R3, a fifth resistor R5, a first switch tube Q1 and a second switch tube Q2.
The non-inverting input terminal of the comparator 461 receives the threshold voltage VREF, the inverting input terminal receives the shutdown control signal XON, the positive power terminal is connected to the first terminal of the second resistor R2, the negative power terminal is grounded, and the output terminal is connected to the first terminal of the first resistor R1 and the second terminal of the second resistor R2.
The first pin of the timer 462 is grounded, the fourth pin receives the input voltage VIN, the second pin receives the shutdown control signal XON, the third pin receives the backlight input signal VLED _ IN, the fifth pin is connected to the first end of the second resistor R2, and the first end of the second resistor R2 is further connected to the first end of the third resistor R3.
The timer 462 has the same function as the timer 362 of the common electrode discharge unit 360 according to the second embodiment of the present invention, and is not described herein again.
The control end of the first switch tube Q1 is connected to the second end of the first resistor R1, the first end of the first switch tube Q1 is connected to the second end of the third resistor R3, and the second end of the first switch tube Q1 is grounded.
The control end of the second switch tube Q2 is connected to the second end of the third resistor R3, the first end of the second switch tube Q2 is connected to the fifth pin of the timer 462, the second end of the second switch tube Q2 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 is grounded.
The clock pulse input terminal CLK of the D flip-flop 463 receives the gate off signal VGL, the data input terminal D is connected to the first terminal of the fifth resistor R5, the temporary storage data output terminal Q is connected to the discharge circuit 464, and the set terminal S is connected to the reset terminal R.
Optionally, D flip-flop 463 is selected from edge D flip-flops.
The control terminal of the discharge circuit 464 is connected to the temporary data output terminal Q of the D flip-flop 463, the first terminal is connected to the common electrode VCOM of the display array 210, and the second terminal is grounded. When the control terminal of the discharge circuit 464 receives a high level, the discharge circuit 464 turns on the current path between the common electrode VCOM and the ground, and when the control terminal receives a low level, the discharge circuit 464 turns off the current path between the common electrode VCOM and the ground.
The discharge circuit 464 includes a fourth resistor R4 and a third switching tube Q3. The control terminal of the third switch Q3 is connected to the temporary data output terminal Q of the D flip-flop 463, the first terminal of the third switch Q3 is connected to the second terminal of the fourth resistor R4, the first terminal of the fourth resistor R4 is connected to the common electrode VCOM, and the second terminal of the third switch Q3 is grounded.
When the lcd device 200 normally works, the shutdown control signal XON is at a high level, the fifth pin of the timer 462 outputs a low level, that is, the backlight output signal VLED _ OUT is at a low level, the comparator 461 does not work, the first switch Q1 and the second switch Q2 are turned off, the gate turn-off signal VGL is at a low level, the temporary data output terminal of the D flip-flop 463 is at a low level, the third switch Q3 is turned off, and the common electrode VCOM is not grounded.
When the lcd device 200 is turned off, the turn-off control signal XON is at a low level, the fifth pin of the timer 462 outputs a high level, i.e., the backlight output signal VLED _ OUT is at a high level, and the comparator 461 operates.
At this time, the shutdown control signal XON is smaller than the threshold voltage VREF, the output terminal of the comparator 461 outputs a high level, the first switch Q1 is turned on, the control terminal of the second switch Q2 is grounded, because the backlight output signal VLED _ OUT is at a high level at this time, the second switch Q2 is turned on, the first terminal of the fifth resistor R5 is at a high level, and the data input terminal of the D flip-flop 463 receives a high level.
Meanwhile, when the lcd device 200 is turned off, the gate turn-off signal VGL is switched from a low level to a high level to generate a rising edge, the clock pulse input terminal CLK of the D flip-flop 463 receives the rising edge, and the temporary data output terminal Q outputs a high level, which has the same voltage value as the input voltage of the data input terminal D. The control terminal of the third switch transistor Q3 is at a high level, the third switch transistor Q3 is turned on, and the common electrode VCOM is grounded, so that the discharging speed of the common electrode VCOM is increased, thereby effectively improving the shutdown afterimage phenomenon of the liquid crystal display device 200.
The third switch Q3 is turned on, and after a time delay of a first predetermined time, the backlight output signal VLED _ OUT is switched to a low level, the comparator 461 stops working, the first switch Q1, the second switch Q2 and the third switch Q3 are turned off, and the common electrode VCOM is disconnected from the ground.
If the voltage value of the shutdown control signal XON is smaller than the threshold voltage VREF due to the unstable circuit, the comparator 461 and the timer 462 operate, the first switch Q1 and the second switch Q2 are turned on, the data input end D of the D flip-flop 463 receives a high level, the gate turn-off signal is switched from a low level to a high level only when the D flip-flop is shutdown, the D flip-flop 463 keeps the low level, the temporary data output end Q still outputs the low level, the third switch Q3 is turned off, and the common electrode VCOM is not grounded.
The utility model discloses the common electrode discharge unit 460 of third embodiment is with common electrode VCOM ground connection when shutting down for common electrode VCOM's the discharge rate to effectively improve liquid crystal display device 200's shutdown afterimage phenomenon.
Further, only when the liquid crystal display device 200 is turned off and the power-off control signal XON is switched to the low level, the backlight output signal VLED _ OUT is switched to the high level, so that the common electrode discharging unit 460 works normally, and the power consumption of the common electrode discharging unit 460 is reduced.
Further, after the timer 462 delays for the first predetermined time, the backlight output signal VLED _ OUT switches to the low level again, the third switching tube Q3 is turned off, and the connection between the common electrode VCOM and the ground is disconnected, so as to avoid the common electrode of the display array 210 from being grounded all the time due to the voltage value fluctuation of the shutdown control signal XON and the false operation of the common electrode discharge unit 460, and the locking phenomenon caused by the false operation occurs, thereby effectively improving the stability of the liquid crystal display device 200, and further reducing the power consumption.
Further, when the liquid crystal display device 200 is turned off, the gate turn-off signal VGL is switched from a low level to a high level, the temporary storage data output end Q of the D flip-flop 463 outputs a high level, if the voltage value of the turn-off control signal XON fluctuates, the comparator 461 and the timer 462 operate, the data input end of the D flip-flop 463 receives the high level, and the data output end Q of the D flip-flop 463 still maintains the low level because the gate turn-off signal VGL is not switched from the low level to the high level, the third switch tube is turned off, and the common electrode VCOM is not grounded, so that the false operation of the common electrode discharge unit 460 caused by the fluctuation of the voltage value of the turn-off control signal XON is avoided, and the stability of the liquid crystal display device 200 is effectively improved.
Fig. 8 is a timing chart showing the shutdown of the liquid crystal display device according to the embodiment of the present invention. Take the example of the common electrode discharge unit as the common electrode discharge unit 460 in the third embodiment of the present invention in fig. 7.
As shown in fig. 8, the shutdown control signal XON, the gate-off signal VGL, and the common electrode voltage VCOM are sequentially arranged from top to bottom. When the lcd device 200 is turned off, the turn-off control signal is switched from high level to low level, the gate turn-off signal is switched from low level to high level, the common electrode discharging unit 460 works to ground the common electrode VCOM, and the voltage of the common electrode VCOM is switched from high level to low level, and it can be seen that the switching of the gate turn-off signal VGL to high level is delayed by the second predetermined time T1 than the switching of the turn-off control signal XON to low level.
Fig. 9 shows a flowchart of the operation when the liquid crystal display device according to the embodiment of the present invention is turned off, where the common electrode discharge unit in the liquid crystal display device is the discharge control unit 260 in fig. 4 as an example, and includes steps S01 to S08.
In step S01, the power unit outputs the shutdown control signal XON.
In step S02, the common electrode discharge unit receives the shutdown control signal XON.
In step S03, the common electrode discharging unit detects a voltage value of the shutdown control signal XON, and if the voltage value is greater than a threshold voltage, performs step S04; if the voltage value is smaller than the threshold voltage, step S06 is executed.
In step S04, the voltage value of the shutdown control signal XON is greater than the threshold voltage, indicating that the display is operating normally and the common electrode discharge unit is not operating.
In step S05, the common electrode VCOM of the display array is normally output.
In step S06, the voltage value of the shutdown control signal XON is smaller than the threshold voltage, indicating that the liquid crystal display device is shutdown and the common electrode discharge unit is operated.
In step S07, the common electrode VCOM is grounded. The common electrode discharge unit grounds the common electrode VCOM of the display array, accelerates the discharge speed of the common electrode VCOM, and thereby effectively improves the shutdown ghost phenomenon of the liquid crystal display device.
To sum up, the utility model provides a common electrode discharge unit is with common electrode VCOM ground connection when shutting down for common electrode VCOM's the discharge rate to effectively improve liquid crystal display device's shutdown afterimage phenomenon.
Further, only when the liquid crystal display device is turned off and the turn-off control signal XON is switched to the low level, the backlight output signal VLED _ OUT is switched to the high level, so that the common electrode discharge unit normally works, and the power consumption of the common electrode discharge unit is reduced.
Furthermore, after the timer delays for the first predetermined time, the backlight output signal VLED _ OUT switches to the low level again, the third switching tube Q3 is turned off, and the connection between the common electrode VCOM and the ground is disconnected, so that the common electrode of the display array is always grounded due to the voltage value fluctuation of the shutdown control signal XON and the false operation of the common electrode discharge unit, and the locking phenomenon caused by the false operation occurs, thereby effectively improving the stability of the liquid crystal display device, and further reducing the power consumption.
Further, when the liquid crystal display device is shut down, the gate turn-off signal VGL is switched from a low level to a high level, the temporary storage data output end Q of the D flip-flop outputs the high level, if the voltage value of the shutdown control signal XON fluctuates, the comparator and the timer work, the data input end of the D flip-flop receives the high level, the data output end Q of the D flip-flop still maintains the low level because the gate turn-off signal VGL is not switched from the low level to the high level, the third switching tube is turned off, the common electrode VCOM is not grounded, false operation of discharge of the common electrode unit caused by fluctuation of the voltage value of the shutdown control signal XON is avoided, and the stability of the liquid crystal display device is effectively improved.
It should be noted that as used herein, the words "during", "when" and "when … …" in relation to the operation of a circuit are not strict terms indicating an action that occurs immediately upon the start of a startup action, but rather there may be some small but reasonable delay or delays, such as various transmission delays, between it and the reaction action (action) initiated by the startup action. The words "about" or "substantially" are used herein to mean that the value of an element (element) has a parameter that is expected to be close to the stated value or position. However, as is well known in the art, there is always a slight deviation that makes it difficult for the value or position to be exactly the stated value. It has been well established in the art that a deviation of at least ten percent (10%) for a semiconductor doping concentration of at least twenty percent (20%) is a reasonable deviation from the exact ideal target described. When used in conjunction with a signal state, the actual voltage value or logic state (e.g., "1" or "0") of the signal depends on whether positive or negative logic is used.
In accordance with the present invention, as set forth above, these embodiments do not set forth all of the details nor limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated.
Claims (10)
1. A common electrode discharge cell of a display array, comprising:
the comparator is characterized in that a non-inverting input end of the comparator receives a threshold voltage, an inverting input end of the comparator receives a shutdown control signal, a positive power supply end receives a backlight output signal, and a negative power supply end is grounded;
a first resistor, a first end of the first resistor being connected to an output end of the comparator;
a control end of the discharge circuit is connected with a second end of the first resistor, a first end of the discharge circuit is connected with a common electrode of the display array, and a second end of the discharge circuit is grounded;
when the control end of the discharge circuit receives a high level, the discharge circuit conducts a current path between the common electrode and the ground; when the control end of the discharge circuit receives a low level, the discharge circuit cuts off a current path between the common electrode and the ground.
2. The common electrode discharge cell of the display array of claim 1, wherein the discharge circuit comprises:
a fourth resistor, a first end of the fourth resistor being connected to the common electrode;
and the control end of the third switching tube is connected with the second end of the first resistor, the first end of the third switching tube is connected with the second end of the fourth resistor, and the second end of the third switching tube is grounded.
3. The common electrode discharge unit of the display array according to claim 2, further comprising, connected between the second terminal of the first resistor and the control terminal of the third switching tube:
the control end of the first switch tube is connected with the second end of the first resistor, and the second end of the first switch tube is grounded;
a first end of the second resistor is connected with a positive power supply end of the comparator, and a second end of the second resistor is connected with an output end of the comparator;
a first end of the third resistor is connected with a first end of the second resistor, and a second end of the third resistor is connected with a first end of the first switch tube;
a control end of the second switching tube is connected with a second end of the third resistor, a first end of the second switching tube is connected with a first end of the third resistor, a second end of the second switching tube is connected with a control end of the third switching tube, and the first end of the second switching tube receives the backlight output signal;
the timer is connected with the second switching tube, receives the power-off control signal and the backlight input signal, and generates the backlight output signal according to the power-off control signal and the backlight input signal;
and a first end of the fifth resistor is connected with the second switch tube, and a second end of the fifth resistor is grounded.
4. The common electrode discharge unit of the display array according to claim 3, wherein the timer is configured to output the backlight output signal as a high level when the power-off control signal is inverted from a high level to a low level, and to output the backlight output signal as a low level after a delay of a first predetermined time;
wherein a voltage value of the backlight output signal at a high level is equal to a voltage value of the backlight input signal.
5. The common electrode discharge unit of the display array according to claim 4, wherein the length of the first predetermined time of the timer is settable by a code.
6. The common electrode discharge unit of the display array according to claim 4, further comprising a D flip-flop connected between the second terminal of the second switch tube and the control terminal of the discharge circuit, wherein a data input terminal of the D flip-flop is connected to the second terminal of the second switch tube, a temporary data output terminal is connected to the control terminal of the third switch tube, and a clock input terminal of the D flip-flop receives a gate-off signal.
7. The common electrode discharge unit of the display array of claim 6, wherein the gate-off signal is inverted from a low level to a high level when the power is off.
8. The common electrode discharge unit of the display array of claim 7, wherein the gate-off signal is toggled from low level to high level after a second predetermined time when the power-off control signal is toggled from high level to low level.
9. A liquid crystal display device comprising: the display device comprises a display array, a grid driving unit for providing grid driving signals for the display array, a source driving unit for providing source signals for the display array, a time schedule controller for controlling the grid driving unit and the source driving unit, and a power unit, wherein the power unit is connected with the time schedule controller and provides shutdown control signals for the time schedule controller when the power unit is shut down; a common electrode discharge unit of the display array of any one of claims 1 to 8;
the common electrode discharge unit is connected with the power unit and the display array, receives the shutdown control signal and the threshold voltage, and discharges the common electrode of the display array according to the shutdown control signal and the threshold voltage.
10. The liquid crystal display device of claim 9, wherein the display array comprises oxide thin film transistors.
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| CN202023279948.5U CN213904905U (en) | 2020-12-30 | 2020-12-30 | Common electrode discharge unit of display array and liquid crystal display device |
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| CN202023279948.5U CN213904905U (en) | 2020-12-30 | 2020-12-30 | Common electrode discharge unit of display array and liquid crystal display device |
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| CN114005418A (en) * | 2021-10-29 | 2022-02-01 | 绵阳惠科光电科技有限公司 | Common voltage generation circuit, display panel drive circuit and display device |
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| CN114495854A (en) * | 2021-12-28 | 2022-05-13 | 绵阳惠科光电科技有限公司 | Driving circuit, driving method and display device |
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