TWI259991B - Discharge device and discharge method and liquid crystal display using thereof - Google Patents

Abstract

A discharge device and discharge method for a LCD is provided. The discharge device includes a first discharge circuit connected to a first capacitor, a second discharge circuit connected to a second capacitor, and a switch circuit connected to the first and the second capacitor. When the power of the LCD driver is turned off suddenly, a discharge signal is provided to activate the switch circuit, thus the switch circuit is open, then the first capacitor is discharged by the first discharge circuit, and the second capacitor is discharged by the second discharge circuit. When the power of the LCD driver is turned on, the switch circuit is inactivated and closed, thus the first and the second capacitor are short. Accordingly, when the power of LCD driver is turned off suddenly, the charge stored in any one of the scan lines of the LCD can be discharged rapidly, and the black line phenomenon can be avoided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge line and method, and more particularly to a discharge line and method for a liquid crystal display (nLCD). Display devices for electronic devices, such as computer screens, televisions, etc., have undergone significant development. Compared with conventional cathode ray tubes (Cathode Ray Tubes, nCRTn), liquid crystal display panels are light in weight, thin in size, and available in area. The advantages of large size, low operating voltage, power saving, and no radiation have become the mainstream of display panels in recent years. In recent years, popular portable electronic products, such as the screen of notebook computer, mobile phone screen, The display screen of the Personal Digital Assistance (nPDAn), etc., only the LCD screen can meet the portable requirements of light weight, small size, small area, etc. Traditionally, a liquid crystal display panel is suddenly powered by its power supply. When it is turned off, it will be caused by the integrated circuit (nICn). The scanning voltage of the liquid crystal display panel remains on one of the scanning lines of the COM scanning line in the X direction or the SEG scanning line in the Y direction. However, since the voltage stabilizing capacitance of the liquid crystal display panel voltage is still maintained at some At a potential, the voltage remaining on the scan line of the C 0 terminal or the SEG terminal is maintained for a relatively long period of time. Basically, the voltage of the liquid crystal display panel is not to be lost due to leakage or passing through a certain discharge path. 〇 In general, a large enough root mean square (Root Mean Square, nRMSn) has accumulated on the LCD panel during the period of residual voltage maintenance.

11549twf.ptd Page 8 1259991 V. Description of the invention (2) Voltage, which produces an observable black line. Please refer to FIG. 1A and FIG. 1B, which are schematic diagrams showing a black line generated by residual voltage on a conventional liquid crystal display panel. In order to solve the above problem, a conventional liquid crystal display panel needs to be provided with a discharge circuit, and when the power source is turned off, the charge on the capacitor in the liquid crystal display panel can be quickly discharged, and the black line generation phenomenon can be eliminated. . Referring to Figure 2, there is shown a circuit diagram of a conventional discharge line of a liquid crystal display panel. In an LCD driver 1C 203, a switching transistor 2 0 6 and a resistor 2 0 8 are included. The switching transistor 2 0 6 is connected to all of the capacitors in a liquid crystal display panel 2 0 1 through a driving switch 204. In addition, the switching transistor 206 is further connected to an external capacitor 4 2 1 0. The purpose of connecting the liquid crystal display panel 2 0 1 to the external capacitor 2 1 0 is to stabilize the scanning voltages of the scanning lines C Ο Μ and SEG, etc. Therefore, the capacitance of the external capacitor is usually quite large, basically liquid crystal. The capacitance in the display panel 201 is 1000 times or more. When the power of the liquid crystal display panel 2 0 1 in FIG. 2 is turned off, the switching transistor 206 is turned on and the liquid crystal display panel 2 0 1 and the external capacitor 2 1 0 are connected to the resistor 2 0 8 to display the liquid crystal display. The capacitor in the panel 2 0 1 and the charge on the external capacitor 2 10 0 are discharged, and the phenomenon of the above black line can be eliminated. However, since the current of the discharge is basically not too large and needs to be limited, and since the capacitance of the external capacitor is relatively large, the time required for the discharge process is long, so that the phenomenon of the above black line cannot be quickly smashed. eliminate. Therefore, a device and method that can shorten the discharge time and quickly eliminate the black line are necessary.

11549 twf.ptd Page 9 1259991 V. SUMMARY OF THE INVENTION (3) SUMMARY OF THE INVENTION In view of the limitations of the above conventional techniques, a first object of the present invention is to provide a discharge line and discharge method which can shorten the discharge time and eliminate the generation of black lines. A second object of the present invention is to provide a discharge line and method for a liquid crystal display panel which can shorten the discharge time of the liquid crystal display panel and eliminate black line generation. Therefore, in order to achieve a certain part of the above object, the present invention provides a discharge line comprising a first discharge circuit connected to a first capacitor, a second discharge circuit connected to a second capacitor, and a switching circuit connected to The first capacitor and the second capacitor; and a discharge signal for starting or turning off the discharge line; wherein when the discharge signal starts the discharge line, the switching circuit is opened, and the first discharge circuit is activated, so that Discharging the first capacitor through the first discharge circuit, and starting the second discharge circuit, so that the second capacitor is discharged via the second discharge circuit; when the discharge line is turned off, the switching circuit is closed, and the first is turned off The discharge circuit and the second discharge circuit short-circuit the first capacitor and the second capacitor. More preferably, the first discharge circuit includes a first switching circuit and a first resistor, and the second discharging circuit includes a second switching circuit and a second resistor. The present invention provides a discharge method including: generating a discharge signal for a first capacitor and a second capacitor; and when the discharge signal is an active signal, the first capacitor and the second capacitor put

11549twf.ptd Page 10 1259991 V. INSTRUCTION DESCRIPTION (4) Electricity; and when the discharge signal is an off signal (i n a c t i v e ), the first capacitor is shorted with the second capacitor. In order to achieve a certain part of the above object, the present invention provides a discharge line for a liquid crystal display panel, comprising a liquid crystal display panel having a first capacitor; a first discharge circuit 'connecting to the first capacitor in the liquid crystal display panel a second discharge circuit connected to a second capacitor; a switching device coupled to the first capacitor and the second capacitor; and a discharge signal for activating or deactivating the discharge line; wherein when the discharge signal is activated In the discharging circuit, the switching circuit is opened, the first discharging circuit is activated, the first capacitor is discharged through the first discharging circuit, and the second discharging circuit is activated, so that the second capacitor is discharged via the second discharging The circuit discharges; when the discharge line is closed, the switching circuit is closed, and the first discharge circuit and the second discharge circuit are closed, so that the first capacitor and the second capacitor are short-circuited together. Preferably, the first capacitor includes at least one of a parasitic capacitance or an external capacitor of the liquid crystal display panel. Preferably, the discharge line of the liquid crystal display panel as described above further includes a set of power detecting means for detecting a power supply of the liquid crystal display panel, and generating the discharge signal when the power source changes. More preferably, the first discharge circuit includes a first switching circuit and a first electrical resistance, and the second discharging circuit includes a second switching circuit and a Second resistance.

11549twf.ptd Page 11 1259991 V. Description of the Invention (5) In order to achieve a certain part of the above object, the present invention provides a discharge method for a liquid crystal display panel, comprising generating a discharge signal for liquid crystal display having a first capacitance a first capacitor and a second capacitor when the discharge signal is a start signal; and the first capacitor and the second capacitor when the discharge signal is a turn-off signal Shorted together. In summary, the discharge circuit and method provided by the present invention, and the discharge line and method of the liquid crystal display panel can provide a discharge circuit when the power of one of the liquid crystal display panels is suddenly turned off, thereby shortening the discharge time of the liquid crystal display panel. And eliminate the black line. The above and other objects, features, and advantages of the present invention will become more apparent from the aspects of the invention. A circuit diagram showing a discharge line is in accordance with a preferred embodiment of the present invention. Referring to FIG. 3A, a discharge line 310 is provided, including a first discharge circuit 310 connected to a first capacitor 312 and a second discharge circuit 320, connected to a second capacitor 322, and A switch circuit 330 is coupled to the first capacitor 312 and the second capacitor 322. In Figure 3A, a discharge signal is provided for activating (a c t i v e ) or inactive discharge line 302. The switching circuit 330 includes a main a (a c t i v e ) switching element or a passive (p a s s i v e ) switching element. In an embodiment of the invention, more preferably, as in Figure 3A

11549 twf.ptd page 12 1259991 V. Description of the Invention (6) The discharge circuit 3〇2, wherein the first discharge circuit 310 includes a first switching circuit 314 and a first resistor 316, and the second discharging circuit 320 includes a The second switching circuit 3 2 4 and a second resistor 3 26 . The first switching circuit 3 1 4 includes an active switching element or a passive switching element. The second switching circuit 3 2 4 includes an active switching element or a passive switching element. More preferably, the switching circuit 303, the first switching circuit 314, and the second switching circuit 314 may include a metal oxide semiconductor (nome), and a bipolar junction (Bipolar Junction). Transistor, MBJ τM) and so on. Figure 3B is a circuit diagram showing a discharge line/system in accordance with another embodiment of the present invention. In FIG. 3B, unlike FIG. 3A, in the first discharge circuit 310, the first switching circuit 314 is located between the first resistor 316 and the ground, and in the second discharge circuit "o" A switching circuit 3 2 4 is located between the second resistor 3 26 and the ground. The circuit configuration of the 3b ^ and 3A diagrams is different, but the result can be obtained from the date of the present invention. In one embodiment of the present invention, the first resistor 316 or the second resistor 326 of FIG. 3B or FIG. 3A may be, for example, a parasitic resistance in a circuit or an actually configured resistor. Hereinafter, FIG. 4A and FIG. 4B The figure is a schematic diagram of the operation of the discharge line of Fig. 3A according to a preferred embodiment of the present invention. The operation of the discharge line of Fig. 3B can also be referred to the description of Fig. 4A and Fig. 4B. 4 A, when the discharge signal is the start discharge line 3 〇 2, the switching circuit 3 3 0 will switch to open (open), and open the first discharge circuit

Page 13 1259991 V. Description of the Invention (7) 3 1 0 , that is, the first switching circuit 3 1 4 of the first discharging circuit 3 1 0 is closed, and thus connected to the first resistor 316, so that the first capacitor 312 is The charge is discharged via the first discharge circuit 310. And the second discharge circuit 320 is turned on, that is, the second switching circuit 324 of the second discharge circuit 320 is closed, and thus connected to the second resistor 3 26 so that the charge in the second capacitor 32 2 passes through the second discharge circuit. 320 discharge. Referring to FIG. 4B, when the discharge signal is off the discharge line 3 0 2, the switching circuit 310 will switch to the closed circuit (c 1 〇se ), so that the first capacitor and the second capacitor are shorted (short) together. The first discharge circuit 310 and the second discharge circuit 320 are turned off, that is, the first switching circuit 314 of the first discharge circuit 31 is opened, and the second switching circuit 3 24 of the second discharge circuit 320 is opened. In summary, in accordance with a preferred embodiment of the present invention, the present invention provides a method of discharging comprising first generating a discharge signal for a first capacitor 312 and a second capacitor 3 22. When the discharge signal is an active signal, the first capacitor 312 and the second capacitor 322 are discharged. When the discharge signal is an inactive signal, the first valley 312 is shorted to the second valley 322. In the following, a schematic diagram of the operation of a discharge line applied to a liquid crystal display panel according to Figs. 5A and 5B is a preferred embodiment of the present invention. Referring to Figure 5A, the present invention provides a discharge line 5 〇 2 suitable for an LCD driver 1C 5〇3. The discharge line 5〇2 includes a first discharge circuit φ 510, a second discharge circuit 520, and a switching circuit 53A. The first discharge circuit 5 10 is connected to a liquid crystal display through a driving switch 5 〇 4

11549twf.ptd Page 14 1259991 V. Description of the invention (8) In the panel 5 0 1 and all the capacitors in the drive switch 5 0 4, in the 5A diagram, the sum of one of the capacitors is a first capacitor 512 means it. The second discharge circuit 520 is connected to a second capacitor 522. The purpose of the liquid crystal display panel 510 being externally connected to the second capacitor 5 2 2 is to stabilize the scan voltage of the scan lines COM and SEG, etc., therefore, the capacitance of the second capacitor 522 is generally quite large, basically It is 1 or more times the capacitance of the liquid crystal display panel 501. In Figure 5A, a discharge signal is provided for active or inactive discharge line 502. The switching circuit 530 includes an active switching element or a passive (p a s s i v e ) switching element. In an embodiment of the present invention, more preferably, the discharge line 502 is as described in FIG. 5A, wherein the first discharge circuit 510 includes a first switching circuit 514 and a first resistor 516, and The second discharge circuit 520 includes a second switching circuit 524 and a second resistor 526. The first switching circuit 5 1 4 includes an active switching element or a passive switching element. The second switching circuit 524 includes an active switching element or a passive switching element. More preferably, the switching circuit 530, the first switching circuit 516 and the second switching circuit 524 may include a metal oxide semiconductor (Metal Oxide Semiconductor, "M0Sn), and a bipolar-connected transistor (Bipolar Junction Transistor, 丨, BJT 丨丨), etc. FIG. 5C is a schematic view showing the operation of a discharge line applied to a liquid crystal display panel according to an embodiment of the present invention. In Fig. 5C, unlike Fig. 5A, in the first discharge circuit 510, the first switching circuit 516 is located between the first resistor 516 and the ground, and at the second discharge.

11549twf.ptd Page 15 1259991 V. INSTRUCTION DESCRIPTION (9) In circuit 5 2 0, the second switching circuit 5 24 is located between the second resistor 5 26 and the ground. The circuit configuration of Fig. 5C and Fig. 5A is different, but the results of the present invention can be achieved. Furthermore, in one embodiment of the invention, the first resistor 516 or the second resistor 526 in Figures 5A through 5C may be, for example, a parasitic resistance in the circuit or an actually configured resistor. Hereinafter, Fig. 5A and Fig. 5B are schematic diagrams showing the operation of a discharge line. The operation of the discharge line of Fig. 5C can also be referred to the description of Figs. 5A and 5B. Referring to FIG. 5A, when the discharge signal is the start discharge line 5 0 2, the switching circuit 530 will switch to open, and turn on the first discharge circuit $5 1 0 , that is, the first discharge circuit 5 The first switching circuit 5 1 4 of 10 is a closed circuit, and thus is connected to the first resistor 516 such that the charge in the first capacitor 512 is discharged via the first discharging circuit 5 10 . And the second discharge circuit 520 is turned on, that is, the second switching circuit 524 of the second discharge circuit 520 is closed, and thus connected to the second resistor 5 26 such that the charge in the second capacitor 52 is via the second discharge circuit. 520 discharge. Referring to FIG. 5B, when the discharge signal is to turn off the discharge line 5 0 2, the switching circuit 530 will switch to close, so that the first capacitor and the second capacitor are shorted together. And closing the first discharge circuit 510 and the second discharge circuit 520, that is, opening the first switching circuit 51 in the first discharge circuit 510, and the second switching circuit 3 in the second discharging circuit 5 2 0 4 open the way. At this time, the liquid crystal display panel 5 0 1 is connected to the second capacitor 5 2 2 through the driving switch 5 0 4 and the switch 5 3 0 to make the scan line

11549twf.ptd Page 16 1259991 V. Description of the Invention (ίο) The scan voltage of COM and SEG can be stabilized by the second capacitor 522. This Fig. 5B shows the case where the liquid crystal display panel 501 is operating normally. In an embodiment of the present invention, it is more preferable that the discharge line 502 of the liquid crystal display panel 501 includes a set of power detecting devices 504 for detecting the liquid crystal display panel 5. 0 1 A power supply, when the power supply changes or is interrupted, the discharge signal is generated to generate one of the operations shown in Figure 5A. More preferably, the discharge line 502 of the liquid crystal display panel 501, wherein the first capacitor 512 further comprises at least one of a parasitic capacitance or an external capacitor of the liquid crystal display panel 501. In summary, according to a preferred embodiment of the present invention, the present invention provides a method for discharging a liquid crystal display panel, comprising: first, generating a discharge signal for a liquid crystal display panel having a first capacitance and a The second capacitor. When the discharge signal is an enable signal, the first capacitor and the second capacitor are discharged. And when the discharge signal is a shutdown signal, shorting the first capacitor and the second capacitor together. In summary, the discharge circuit and method provided by the present invention, and the discharge circuit and method of the liquid crystal display panel can be used to provide a discharge circuit 502 when a power supply of the liquid crystal display panel 501 is suddenly turned off. The capacitance on the broom line or other portion of the liquid crystal display panel 501, that is, the first capacitor 51 can be quickly discharged without generating black lines. Although the second capacitor 522, that is, an external capacitor, has a large capacitance value and cannot be discharged quickly, since the power supply of the liquid crystal display panel 510 is turned off, the external capacitor discharge circuit 5 2 0 and the liquid crystal Display panel 5 0 1

11549twf.ptd Page 17 1259991 V. Description of the invention (11) On, so it does not affect the liquid crystal display panel 5 0 1 to make black lines. In summary, the discharge circuit and method provided by the present invention, and the discharge line and method of the liquid crystal display panel can provide a discharge circuit when the power of one of the liquid crystal display panels is suddenly turned off, thereby shortening the discharge time of the liquid crystal display panel. And eliminate the black line. Although the present invention has been described above in terms of a preferred embodiment, it is not intended to limit the invention, and it is obvious to those skilled in the art that the present invention may be modified and retouched without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

11549twf.ptd Page 18 1259991 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A and FIG. 1B are diagrams showing a schematic diagram of a black line generated by a residual voltage on a conventional liquid crystal display panel; FIG. 2 is a circuit diagram showing a A discharge circuit of a conventional liquid crystal display panel; FIG. 3A is a circuit diagram showing a discharge line according to a preferred embodiment of the present invention; and FIG. 3B is a circuit diagram showing a discharge line according to a circuit diagram Another embodiment of the present invention; FIGS. 4A and 4B are schematic diagrams showing the operation of a discharge line according to a preferred embodiment of the present invention; FIGS. 5A and 5B are diagrams showing a discharge line applied to a liquid crystal display. A schematic diagram of the operation of the panel is based on a preferred embodiment of the present invention; and FIG. 5C is a schematic diagram of the operation of a discharge line for a liquid crystal display panel, in accordance with an embodiment of the present invention. Schematic description: 2 0 1 , 5 0 1 : LCD panel 203, 503 : LCD driver 1C 2 0 4, 5 0 4 ·• Drive switch 2 0 6 : Switching transistor 208, 316, 326, 516, 526 : Resistors 210, 312, 322, 512, 522: Capacitors 3 0 2, 5 0 2 : Discharge lines Ι 310, 320, 510, 520: Discharge circuits 314, 324, 330, 514, 524, 530: switching circuits

11549twf.ptd Page 19 1259991 Schematic description of the COM, SEG: Scanning line 1 11549twf.ptd Page 20

Claims (1)

1259991 VI. Patent Application Range 1. A discharge circuit comprising: a first discharge circuit connected to a first capacitor; a second discharge circuit connected to a second capacitor; a switch circuit connected to the a first capacitor and the second capacitor; and a discharge signal for actively or inactively discharging the discharge line; wherein when the discharge signal activates the discharge line, the switching circuit is opened (ο pe η ) Activating the first discharge circuit such that the first capacitor discharges through the first discharge circuit, and starting the second discharge circuit, so that the second capacitor is discharged via the second discharge circuit; when the discharge circuit is turned off The switching circuit is closed (c 1 〇se ), and the first discharging circuit and the second discharging circuit are turned off, so that the first capacitor and the second capacitor are shorted together. 2. The discharge circuit of claim 1, further comprising a set of power detecting means for generating a discharge signal when a power source changes. 3. The discharge circuit of claim 1, wherein the switching circuit comprises an active (a c t i v e ) switching element and one of a passive (p a s s i v e ) switching element. 4. The discharge circuit of claim 1, wherein the switching circuit comprises one of a metal oxide semiconductor (MOS) and a bis-carrier-connected transistor (BJT). 5 · The discharge line as described in item 1 of the patent application, wherein 11549twf.ptd Page 21 1259991 VI. Patent Application The first discharge circuit includes a first switching circuit and a first resistor, and the second discharging circuit includes a second switching circuit and a second resistor. 6. The discharge circuit of claim 5, wherein the first resistor or the second resistor comprises one of a parasitic resistance of the discharge circuit or a resistor of an actual configuration. 7. The discharge circuit of claim 5, wherein the first switching circuit comprises an active switching element, and one of the passive switching elements, and the second switching circuit comprises an active switching element, One of them with a passive switching element. 8. The discharge circuit of claim 7, wherein the first switching circuit comprises a metal oxide semiconductor (MOS), one of a bipolar carrier connected to a crystal (BJT), and the second switching The circuit includes one of a metal oxide semiconductor (MOS) and a bipolar connected transistor (BJT). A discharge method, comprising: generating a discharge signal for a first capacitor and a second capacitor; and discharging the first capacitor and the second capacitor when the discharge signal is an active signal; And when the discharge signal is an inactive signal, the first capacitor and the second capacitor are shorted together. 10. The discharge line 5 of the liquid crystal display panel comprises: a liquid crystal display panel having a first capacitance; a first discharge circuit connected to the first one of the liquid crystal display panels; and a second discharge circuit Connected to a second capacitor; 11549twf.ptd Page 22 1259991 6. Patent application scope 1 switch device connected to the first capacitor and the second capacitor; and a discharge signal for actively or inactively discharging the discharge line When the discharge signal activates the discharge line, the switching circuit is opened (ο P e η ), the first discharge circuit is activated, the first capacitor is discharged through the first discharge circuit, and the second discharge is activated. a circuit that causes the second capacitor to be discharged via the second discharge circuit; when the discharge line is closed, 'closes the switching circuit (c 1 〇se )' and turns off the first discharge circuit and the second discharge circuit, so that the circuit The first capacitor is shorted to the second capacitor. Φ 11. The discharge line of the liquid crystal display panel of claim 10, wherein the first capacitor comprises at least one of a parasitic capacitance or an external capacitor of the liquid crystal display panel. 12. The discharge circuit of the liquid crystal display panel according to claim 10, further comprising a power detecting device for detecting a power supply of the liquid crystal display panel, when the power source changes, generating The discharge signal. 13. The discharge circuit of a liquid crystal display panel according to claim 10, wherein the switching circuit comprises an active switching element and one of the passive switching elements. 14. The 放电 discharge line of a liquid crystal display panel according to claim 13 wherein the switching circuit comprises a metal oxide semiconductor (MOS) and a bipolar connected transistor (BJT). one. </ RTI> </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; And the second discharge circuit includes a second switching circuit and a second resistor. 16. The discharge line of a liquid crystal display panel according to claim 15, wherein the first resistor or the second resistor comprises one of a parasitic resistance of the discharge circuit or a resistor of an actual configuration. 17. The discharge circuit of the liquid crystal display panel of claim 15, wherein the first switching circuit comprises an active switching element, and one of the passive switching elements, and the second switching circuit includes An active switching element, and a passive switching element, wherein: - 18. The discharge circuit of the liquid crystal display panel of claim 17, wherein the first switching circuit comprises a metal oxide semiconductor (MOS), One of the bipolar-connected transistors (BJT), and the second switching circuit includes a metal oxide semiconductor (MOS), and one of the bi-carrier-connected transistors (BJT). 19. A method of discharging a liquid crystal display panel, comprising: generating a discharge signal for a liquid crystal display panel having a first capacitance and a second capacitance; when the discharge signal is an active signal, The first capacitor and the second capacitor are discharged; and when the discharge signal is an inactive signal, the first capacitor and the second capacitor are shorted together. The method of discharging a liquid crystal display panel according to claim 19, wherein the first capacitor includes at least one parasitic capacitance or an external connection of the liquid crystal display panel. One of the capacitors. 2. The method of discharging a liquid crystal display panel according to claim 19, further comprising a power detecting device for detecting a power supply of the liquid crystal display panel, when the power source changes, The discharge signal is generated. 11549twf.ptd Page 25