CN114373422A - Light emitting diode driving circuit and light emitting diode driving circuit configuration - Google Patents
Light emitting diode driving circuit and light emitting diode driving circuit configuration Download PDFInfo
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- CN114373422A CN114373422A CN202210115718.XA CN202210115718A CN114373422A CN 114373422 A CN114373422 A CN 114373422A CN 202210115718 A CN202210115718 A CN 202210115718A CN 114373422 A CN114373422 A CN 114373422A
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0264—Details of driving circuits
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0233—Improving the luminance or brightness uniformity across the screen
Abstract
The invention discloses a light-emitting diode driving circuit and a light-emitting diode driving circuit configuration. The control transistor is coupled to the data line, the first node and the first signal line. The driving transistor is coupled to the first voltage source, the second node and the first node. The capacitor is coupled to the first node and the first end of the driving transistor. The light emitting diode is coupled to the second node and a second voltage source. The shunt transistor is coupled to the second node, the third voltage source and the second signal line.
Description
Technical Field
The present invention relates to a light emitting diode driving circuit and a light emitting diode driving circuit configuration, and more particularly, to a light emitting diode driving circuit including a shunt circuit for reducing a luminance difference between a bright area and a dark area during local dimming, and a circuit configuration design of the light emitting diode driving circuit.
Background
In the past display devices, backlight is generally provided in a side-in or direct-out manner, and all backlight sources are turned on or off by Global dimming (Global dimming), but with the development of Light Emitting Diodes (LEDs), a single backlight module is divided into a plurality of independently controlled backlight areas, and the lighting or turning of different areas is controlled by Local dimming in coordination with a picture, so that the picture presented by the display device is more detailed, and a display effect with higher contrast is provided.
In order to control local dimming, the led must be provided with a driving circuit to turn on or off the led, but in the actual operation of the switch, the brightness of the led is changed by the characteristics of the circuit elements in the conventional driving circuit, so that the bright area to be turned on and the dark area to be turned off generate a significant brightness difference in the full frame, thereby affecting the display quality of the device.
In view of the foregoing, the present inventors have devised and designed a light emitting diode driving circuit and a light emitting diode driving circuit configuration to solve the problems of the prior art and further enhance the industrial application.
Disclosure of Invention
In view of the problems of the prior art, an object of the present invention is to provide a light emitting diode driving circuit and a light emitting diode driving circuit configuration, which solve the problem of brightness difference between a display area and a dark area when a display panel performs local dimming.
In view of the above, the present invention provides a light emitting diode driving circuit, which includes a control transistor, a driving transistor, a capacitor, a light emitting diode, and a shunt transistor. The first end of the control transistor is coupled to the data line, the second end of the control transistor is coupled to the first node, and the control end of the control transistor is coupled to the first signal line. The first terminal of the driving transistor is coupled to the first voltage source, the second terminal of the driving transistor is coupled to the second node, and the control terminal of the driving transistor is coupled to the first node. The first end of the capacitor is coupled to the first node, and the second end of the capacitor is coupled to the first end of the driving transistor. The first end of the light emitting diode is coupled to the second node, and the second end of the light emitting diode is coupled to the second voltage source. The first end of the shunt transistor is coupled to the second node, the second end of the shunt transistor is coupled to the third voltage source, and the control end of the shunt transistor is coupled to the second signal line.
In the embodiment of the invention, when the light emitting diode driving circuit is in a bright area, the first signal line transmits a control signal to turn on the control transistor, so that a data signal of the data line is transmitted to the control end of the driving transistor, and a current flows through the light emitting diode, and the second signal line turns off the shunt transistor.
In the embodiment of the invention, when the light emitting diode driving circuit is in a dark region, the first signal line turns off the control transistor, and the second signal line transmits the shunt signal to turn on the shunt transistor, so that the passing current flows from the second node to the shunt transistor.
In an embodiment of the present invention, the operating voltage of the second node is less than the threshold voltage of the light emitting diode.
In an embodiment of the present invention, the channel width of the driving transistor is about 2 times the channel width of the shunt transistor.
The invention provides a light-emitting diode driving circuit configuration which is arranged in a circuit block, wherein the side edge of the circuit block comprises a first signal line, a data line, a first voltage source and a second voltage source, and the light-emitting diode driving circuit configuration comprises a first transistor, a second transistor, a capacitor, a first light-emitting diode, a second light-emitting diode, a third light-emitting diode and a fourth light-emitting diode. The first side of the first transistor is coupled to the data line, and the second side of the first transistor, which is adjacent to the first side, is coupled to the first signal line. The first side of the second transistor is coupled to the first voltage source, the second side of the second transistor opposite to the first side is coupled to the transmission line, the transmission line extends to the third side and the fourth side of the second transistor opposite to the second transistor, and the transmission line is coupled to the second voltage source. The capacitor is arranged between the first transistor and the second transistor. The first light emitting diode and the second light emitting diode are arranged in series on the transmission line on the third side of the second transistor, and the third transistor and the fourth transistor are arranged in series on the transmission line on the fourth side of the second transistor.
In an embodiment of the invention, a channel width of the second transistor is 1 to 10 times of a channel width of the first transistor.
In the embodiment of the invention, the channel width of the first transistor is 3 w-30 w, and the channel width of the second transistor is 30 w-300 w.
In an embodiment of the invention, the led driving circuit arrangement further includes a third transistor disposed between the second transistor and the transmission line on a third side of the second transistor, a first side of the third transistor is coupled to the second signal line and a third voltage source, and a second side of the third transistor opposite to the first side is coupled to the transmission line.
In an embodiment of the present invention, the channel width of the second transistor is about 2 times the channel width of the third transistor.
In view of the above, the led driving circuit and the led driving circuit configuration of the present invention can pass the current through the driving transistor in the dark region by setting the shunt transistor, so as to reduce the problem of the negative drift of the voltage characteristic of the transistor, and avoid the display quality from being affected by the too large brightness difference between the bright region and the dark region in the full picture. The circuit configuration of the led driving circuit designs the arrangement positions of the transistors and the width of the channel between the transistors, so that the transistor device can achieve the desired driving and shunting effects, and the problem of the brightness difference can be solved.
Drawings
In order to make the technical features, contents and advantages of the present invention, and the effects achieved thereby, more apparent, the present invention will now be described with reference to the accompanying drawings in which:
fig. 1 is a schematic diagram of a light emitting diode driving circuit according to an embodiment of the invention.
Fig. 2A and 2B are schematic diagrams illustrating an operation of the led driving circuit in a bright area according to the embodiment of the invention.
Fig. 3A and fig. 3B are schematic diagrams illustrating an operation of the led driving circuit in a dark area according to the embodiment of the invention.
Fig. 4 is a circuit configuration diagram of an led driving circuit according to an embodiment of the invention.
Fig. 5A and 5B are schematic diagrams of transistors in a light emitting diode driving circuit according to an embodiment of the invention.
Fig. 6 is a circuit configuration diagram of an led driving circuit according to another embodiment of the invention.
[ notation ] to show
10, 11, 12, 20, 30 LED drive circuit
21 circuit block
A: transistor structure
C, C1, C2 capacitor
D is drain electrode
Data line
G is grid
I1, I2 passing current
L, L1 transmission line
L2 branch line
LED-light emitting diode
LED1 first light emitting diode
LED2 second light emitting diode
LED3 third light emitting diode
LED4 fourth light emitting diode
N1 first node
N2 second node
OVDD the first voltage source
OVSS secondary voltage source
OVSS2 third Voltage Source
S is source electrode
Scan1 first Signal line
Scan2 second Signal line
T1 control transistor
T2 Driving transistor
T3 shunt transistor
T11, T21 first transistor
T12, T22 second transistor
T23 third transistor
U: transistor unit
Detailed Description
In order to facilitate understanding of the technical features, contents, advantages and effects achieved by the present invention, the present invention will now be described in detail by way of embodiments in conjunction with the accompanying drawings, wherein the drawings are provided for illustration and supplementary description, and are not necessarily to be construed as being true to scale and precise in arrangement after the present invention is implemented, and therefore, the drawings should not be construed as limiting the scope of the present invention in practical application, in view of the relationship between the drawings and the arrangement.
In the drawings, the thickness or width of the substrate, panel, region, line, etc. is exaggerated for clarity. Like reference numerals refer to like elements throughout the specification. It will be understood that when an element such as a substrate, panel, region or line is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connected," may refer to physical and/or electrical connections. Further, "electrically connected" or "coupled" may mean that there are additional elements between the elements. Further, it will be understood that, although the terms "first," "second," "third" and/or the like may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should be used to distinguish one element, component, region, layer and/or section from another element, component, region, layer and/or section. Therefore, they are used for descriptive purposes only and not to be construed as indicating or implying relative importance or order relationships thereof.
Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present invention and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Please refer to fig. 1, which is a schematic diagram of a light emitting diode driving circuit according to an embodiment of the invention. As shown, the light emitting diode driving circuit 10 includes a control transistor T1, a driving transistor T2, a capacitor C, a light emitting diode LED, and a shunt transistor T3. The first terminal of the control transistor T1 is coupled to the Data line Data, the second terminal of the control transistor T1 is coupled to the first node N1, and the control terminal of the control transistor T1 is coupled to the first signal line Scan 1. The first terminal of the driving transistor T2 is coupled to the first voltage source OVDD, the second terminal of the driving transistor T2 is coupled to the second node N2, and the control terminal of the driving transistor T2 is coupled to the first node N1. A first terminal of the capacitor C is coupled to the first node N1, and a second terminal of the capacitor C is coupled to a first terminal of the driving transistor T2. The first terminal of the light emitting diode LED is coupled to the second node N2, and the second terminal of the light emitting diode LED is coupled to the second voltage source OVSS. A first terminal of the shunt transistor T3 is coupled to the second node N2, a second terminal of the shunt transistor T3 is coupled to the third voltage source OVSS2, and a control terminal of the shunt transistor T3 is coupled to the second signal line Scan 2.
When the first signal line Scan1 transmits a control signal to the control terminal of the control transistor T1, the control transistor T1 is turned on, and a Data signal transmitted from the Data line Data is transmitted to the control terminal of the driving transistor T2, thereby controlling the gate operating voltage of the driving transistor T2. Since the first terminal of the driving transistor T2 is connected to the first voltage source OVDD with a high voltage and the second terminal is connected to the second voltage source OVSS with a low voltage, the gate operating voltage can determine the passing current flowing from the high voltage terminal (e.g. 20V) to the low voltage terminal (e.g. 0V), by which the LED is lit. The light emitting diode LED can be used as a backlight (back light) in the display panel, and when the display panel performs local dimming (local dimming), the display effect of the panel can be improved by dividing the display panel into a bright area and a dark area, the light emitting diode LED in the bright area is lit by the driving circuit, and the dark area is unlit without current passing through the light emitting diode LED.
In the dark region, in order to prevent the current from passing through the light emitting diode LED, the Data signal of the Data line Data may be maintained at a low potential to turn off the driving transistor T2, so that the current cannot pass through the light emitting diode LED. However, when no current flows through the driving transistor T2, the threshold voltage of the transistor will drift in the negative direction, and the magnitude of the drift is larger than that of the threshold voltage drifting in the positive direction when the current flows through, so that the dark region and the bright region are greatly different. When the display panel displays a full screen with the same data setting, the above difference will cause the brightness difference between the bright area and the dark area on the display, which affects the display effect.
In the present embodiment, the shunt transistor T3 is coupled to the second node between the driving transistor T2 and the light emitting diode LED, and when the light emitting diode driving circuit 10 is in the dark region, the Data line Data still transmits the Data signal to turn on the driving transistor T2, so that the current continues to pass through the driving transistor T2. At this time, the shunt signal transmitted by the second signal line Scan2 turns on the shunt transistor T3, so that the potential of the second node N2 is higher than the threshold voltage of the LED, and the passing current is shunted by the second node N2, flows to the third voltage source OVSS2 through the shunt transistor T3, and does not flow through the LED to maintain the dark setting. The third voltage source OVSS2 may be a low voltage source similar to the second voltage source OVSS, and in another embodiment, the third voltage source OVSS2 and the second voltage source OVSS may be the same low voltage source.
Fig. 2A and fig. 2B are schematic diagrams illustrating an operation of the led driving circuit in a bright area according to an embodiment of the present invention, wherein fig. 2A is a signal waveform diagram of the bright area operation, and fig. 2B is a corresponding current diagram of the led driving circuit. When the led driving circuit 11 operates in the bright area, the first signal line Scan1 transmits a Scan signal to the control transistor T1, for example, a high-level signal of 30V, and turns on the control transistor T1 according to the timing sequence, so that the Data signal transmitted by the Data line Data can be transmitted to the driving transistor T2, and the gate operating voltage (Vg) of the driving transistor T2 is controlled. In the embodiment, the voltage of the data signal is 16V, the first voltage source OVDD coupled to the driving transistor T2 is a high voltage terminal of 20V, the second voltage source OVSS is a low voltage terminal of 0V, the drain-source voltage (Vds) of the driving transistor T2 is 10V, the gate-source voltage (Vgs) is 6V, and the driving transistor T2 is turned on by the gate operation voltage so that a current I1 (e.g., 10mA) flows from the high voltage terminal to the low voltage terminal, and flows through the light emitting diode LED to emit light.
During the bright area operation, the second signal line Scan2 maintains a low voltage level of-9V, so that the shunt transistor T3 maintains an off state, and thus the pass current I1 only passes through the path of the light emitting diode LED, but not through the shunt path, and the light emitting diode LED emits light in the bright area according to the driving of the Scan signal and the data signal.
Fig. 3A and fig. 3B are schematic diagrams illustrating an operation of the led driving circuit in a bright area according to an embodiment of the present invention, wherein fig. 3A is a signal waveform diagram illustrating a dark area operation, and fig. 3B is a corresponding current diagram of the led driving circuit. As shown, when the led driving circuit 11 operates in the dark area, the first signal line Scan1 also transmits a Scan signal to the control transistor T1, for example, a high signal of 30V, to turn on the control transistor T1 according to the timing sequence, so that the Data signal transmitted by the Data line Data can be transmitted to the driving transistor T2, and the gate operating voltage (Vg) of the driving transistor T2 is controlled. In this embodiment, the voltage of the data signal is 7V, the first voltage source OVDD coupled to the driving transistor T2 is a high voltage terminal of 20V, and the second voltage source OVSS is a low voltage terminal of 0V. After the driving transistor T2 is turned on by the voltage of the data signal, in order to prevent the pass current I2 from flowing through the LED path, the second signal line Scan2 transmits the shunt signal to the control terminal of the shunt transistor T3, and turns on the shunt transistor T3 to perform the shunt operation. Since the first terminal of the shunt transistor T3 is coupled to the second node N2, i.e., the source terminal of the driving transistor T2, when the shunt transistor T3 is turned on, since the shunt transistor T3 is designed to have a size such that the operating voltage (Vs) of the second node N2 is less than the threshold voltage (Vth) of the light emitting diode LED, the current cannot pass through the light emitting diode LED, but passes through the shunt transistor T3 via a shunt path.
In the present embodiment, the channel width of the driving transistor T2 can be 1.5 times to 3 times that of the shunt transistor T3, for example, a preferred ratio can be about 2 times, so that the impedance of the shunt transistor T3 is not smaller than the LED itself, and the operating voltage of the second node N2, i.e. the source operating voltage of the driving transistor, can be smaller than the threshold voltage of the LED by the matching design in size, and will not pass through the LED by the current I2, but the operating voltage is still larger than the third voltage source OVSS2, so that the current I2 flows to the third voltage source OVSS2 along the shunt path through the shunt transistor T3. The shunt transistor T3 can operate in a linear region, the shunt signal received by the shunt transistor T3 is large enough to ensure that the shunt transistor T3 is turned on, and the signal transmitted by the second signal line Scan2 can be 15V.
Under the operation of the bright area and the dark area, the driving transistor T2 has current flowing through it regardless of the operation in the bright area or the dark area, so as to avoid the problem of the threshold voltage shifting toward the negative direction in the dark area caused by the driving transistor T2. When the display panel is presented in a full picture, the dark area can not greatly improve the brightness due to the rise of current, and the brightness difference with the bright area is obvious, so that the display effect is prevented from being influenced by the overlarge brightness difference between the bright area and the dark area.
Please refer to fig. 4, which is a circuit configuration diagram of an led driving circuit according to an embodiment of the invention. As shown in the figure, the led driving circuit 20 is disposed in the circuit block 21, the side of the circuit block 21 includes a first signal line Scan1, a Data line Data, a first voltage source OVDD and a second voltage source OVSS, the first signal line Scan1 and the Data line Data are disposed on the right side of the circuit block 21, the first voltage source OVDD is a high voltage end and is disposed on the right side of the circuit block 21, and the second voltage source OVSS is a low voltage and is disposed on the left side of the circuit block 21. The circuit configuration of the light emitting diode driving circuit 20 includes a first transistor T11, a second transistor T12, a capacitor C1, a first light emitting diode LED1, a second light emitting diode LED2, a third light emitting diode LED3, and a fourth light emitting diode LED 4.
In the present embodiment, a first side (right side) of the first transistor T11 is coupled to the Data line Data, and a second side (upper side) of the first transistor T11 adjacent to the first side is coupled to the first signal line Scan 1. A first side (right side) of the second transistor T12 is coupled to the first voltage source OVDD, a second side (left side) of the second transistor T12 opposite to the first side is coupled to a transmission line L, the transmission line L extends to a third side (lower side) and a fourth side (upper side) of the second transistor T12 opposite to each other, and the transmission line L is coupled to the second voltage source OVSS. The capacitor C1 is disposed between the first transistor T11 and the second transistor T12. The first light emitting diode LED1 is disposed in series with the second light emitting diode LED2 on the transmission line L of the third side of the second transistor T12, and the third light emitting diode LED3 is disposed in series with the fourth light emitting diode LED4 on the transmission line L of the fourth side of the second transistor T12.
The circuit schematic of the led driving circuit 20 can refer to the foregoing embodiment, wherein the first transistor T11 corresponds to the control transistor T1, and the second transistor T12 corresponds to the driving transistor T2. When the first signal line Scan1 transmits a control signal to the control terminal of the first transistor T11, the first transistor T11 is turned on, so that the Data signal transmitted by the Data line Data can be transmitted to the control terminal of the second transistor T12 through the first transistor T11, and the gate operating voltage of the second transistor T12 is controlled. The second transistor T12 has a first terminal connected to the first voltage source OVDD with a high voltage, a second terminal connected to the second voltage source OVSS with a low voltage, and a gate operating voltage determining a passing current flowing from the high voltage terminal to the low voltage terminal, wherein the passing current passes through the transmission line L and sequentially passes through the first LED1, the second LED2, the third LED3 and the fourth LED4 to turn on the LEDs.
In designing the circuit configuration of the first transistor T11 and the second transistor T12, the area of the transistor, i.e., the width-to-length ratio (W/L) of the transistor, is determined, and for the important consideration of the configuration, the channel width of the second transistor T12 may be 1 to 10 times the channel width of the first transistor T11, for example, the channel width of the first transistor T11 may be 3W to 30W, and the channel width of the second transistor T12 may be 30W to 300W. In the present embodiment, the channel width of the first transistor T11 is 6w, and the length is 5.5; the second transistor T12 has a channel width of 60w and a length of 5.5.
Please refer to fig. 5A and 5B, which are schematic diagrams of transistors in a light emitting diode driving circuit according to an embodiment of the invention. Fig. 5A is a schematic diagram of a transistor, and fig. 5B is a schematic diagram of a transistor structure. In the first transistor T11 and the second transistor T12 in the previous figures, the transistors may be arranged in a zigzag manner in fig. 5A, in which the source S and drain D lines are alternately arranged in the same direction, and the gate G line is arranged between the source S and drain D lines in a zigzag manner. In fig. 5A, the block of the transistor structure a is further illustrated by the schematic structure of fig. 5B, wherein the transistor structure a may be composed of a source S, a drain D and a gate G at the control end, the drain D is a Y-like electrode, and the source S is an I-like electrode disposed on the line of the gate G. In each transistor unit U, the distance between the source S and the drain D is the channel length, and the channel width is the area between the source S and the drain D divided by the channel length. The first transistor T11 or the second transistor T12 of the previous embodiment can be drawn in a similar manner to achieve the desired aspect ratio.
In the group of the plurality of transistor units U, the transistors may generate a huge feed-through effect (feed-through effect), and thus the effect is suppressed by providing a sufficiently large capacitor C1, in the present embodiment, the capacitor C1 is in the range of about 100 to 1000 pF.
Fig. 6 is a circuit configuration diagram of a light emitting diode driving circuit according to another embodiment of the invention. As shown in the figure, the led driving circuit 30 is disposed in the circuit block 31, the side of the circuit block 31 includes a first signal line Scan1, a second signal line Scan2, a Data line Data, a first voltage source OVDD, a second voltage source OVSS and a third voltage source OVSS2, the first signal line Scan1, the second signal line Scan2 and the Data line Data are disposed on the right side of the circuit block 31, the first voltage source OVDD is a high voltage end and is disposed on the right side of the circuit block 31, and the second voltage source OVSS and the third voltage source OVSS2 are low voltages and are disposed on the left side of the circuit block 31. The circuit configuration of the light emitting diode driving circuit 30 includes a first transistor T21, a second transistor T22, a third transistor T23, a capacitor C2, a first light emitting diode LED1, a second light emitting diode LED2, a third light emitting diode LED3, and a fourth light emitting diode LED 4.
In the present embodiment, a first side (right side) of the first transistor T21 is coupled to the Data line Data, and a second side (upper side) of the first transistor T21 adjacent to the first side is coupled to the first signal line Scan 1. A first side (right side) of the second transistor T22 is coupled to the first voltage source OVDD, a second side (left side) of the second transistor T22 opposite to the first side is coupled to the transmission line L1, the transmission line L1 extends to a third side (lower side) and a fourth side (upper side) of the second transistor T22, and the transmission line L1 is coupled to the second voltage source OVSS. The capacitor C2 is disposed between the first transistor T21 and the second transistor T22. The first light emitting diode LED1 is disposed in series with the second light emitting diode LED2 on the transfer line L1 of the third side of the second transistor T22, and the third transistor LED3 is disposed in series with the fourth transistor LED4 on the transfer line L1 of the fourth side of the second transistor T22. Unlike the previous embodiment, the led driving circuit 30 includes a third transistor T23 disposed between the lower side of the second transistor 22 and the transmission line L1, a first side (right side) of the third transistor T23 is coupled to the second signal line Scan2 and the shunting line L2, the shunting line L2 is coupled to a third voltage source OVSS2, and a second side (left side) of the third transistor T23 is coupled to the transmission line L1.
The circuit schematic of the led driving circuit 30 can refer to the foregoing embodiment, wherein the first transistor T21 corresponds to the control transistor T1, the second transistor T22 corresponds to the driving transistor T2, and the third transistor corresponds to the shunt transistor T3. When the bright region is operated, the first signal line Scan1 transmits a control signal to the control terminal of the first transistor T21, turning on the first transistor T21, so that the Data signal transmitted by the Data line Data can be transmitted to the control terminal of the second transistor T22 through the first transistor T21, and controlling the gate operating voltage of the second transistor T22. The first terminal of the second transistor T22 is connected to the first voltage source OVDD with a high voltage, the second terminal is connected to the second voltage source OVSS with a low voltage, the gate operating voltage determines the passing current flowing from the high voltage terminal to the low voltage terminal, and the passing current flows through the transmission line L1 and sequentially passes through the first LED1, the second LED2, the third LED3 and the fourth LED4, so as to turn on the LEDs.
The arrangement areas of the first transistor T21 and the second transistor T22 can refer to the foregoing embodiments, and the same contents will not be repeated, in this embodiment, the channel width of the second transistor T22 can be 2 times that of the third transistor T23, for example, the channel width of the second transistor T22 is 60w, and the length is 5.5; the third transistor T23 has a channel width of 30w and a length of 5.5. When the dark area is operated, the second signal line Scan2 transmits the shunt signal to the third transistor T23, turns on the third transistor T23, and based on the channel width design of the second transistor T22 and the third transistor T23, the current passing through the second transistor T22 will not flow through the first LED1, the second LED2, the third LED3 and the fourth LED4 on the transmission line L1, but flow from the shunt line L2 to the third voltage source OVSS2 through the third transistor T23.
In the present embodiment, a current flows through the second transistor T22 in both bright and dark regions, so as to avoid the problem of the threshold voltage of the second transistor T22 drifting in the negative direction in the dark region. When the display panel is presented in a full picture, the dark area can not greatly improve the brightness due to the rise of current, and the brightness difference with the bright area is obvious, so that the display effect is prevented from being influenced by the overlarge brightness difference between the bright area and the dark area.
The foregoing is by way of example only and is not limiting. It is intended that all equivalent modifications or variations without departing from the spirit and scope of the present invention shall be included in the appended claims.
Claims (10)
1. A light emitting diode driving circuit, comprising:
a control transistor, a first end of which is coupled to the data line, a second end of which is coupled to the first node, and a control end of which is coupled to the first signal line;
a driving transistor, a first terminal of which is coupled to a first voltage source, a second terminal of which is coupled to a second node, and a control terminal of which is coupled to the first node;
a capacitor, a first end of which is coupled to the first node, and a second end of which is coupled to the first end of the driving transistor;
a light emitting diode, a first end of which is coupled to the second node, and a second end of which is coupled to a second voltage source; and
and a first end of the shunt transistor is coupled to the second node, a second end of the shunt transistor is coupled to a third voltage source, and a control end of the shunt transistor is coupled to a second signal line.
2. The led driving circuit according to claim 1, wherein when the led driving circuit is in a bright area, the first signal line transmits a control signal to turn on the control transistor, so that a data signal of the data line is transmitted to the control terminal of the driving transistor, such that the current flows through the led and the second signal line turns off the shunt transistor.
3. The led driving circuit according to claim 1, wherein the first signal line turns off the control transistor and the second signal line transmits a shunt signal to turn on the shunt transistor when the led driving circuit is in a dark region, so that a pass current flows from the second node to the shunt transistor.
4. The light emitting diode driving circuit as claimed in claim 3, wherein the operating voltage of the second node is less than the threshold voltage of the light emitting diode.
5. The light emitting diode driving circuit as claimed in claim 1, wherein the channel width of the driving transistor is about 2 times the channel width of the shunting transistor.
6. An LED driving circuit arrangement is arranged in a circuit block, the circuit block is provided with a first signal line, a data line, a first voltage source and a second voltage source, the LED driving circuit arrangement comprises:
a first transistor, a first side of which is coupled to the data line, and a second side adjacent to the first side of which is coupled to the first signal line;
a second transistor, a first side of which is coupled to the first voltage source, a second side of which opposite to the first side is coupled to a transmission line, the transmission line extends to a third side and a fourth side of which opposite to the second transistor, and the transmission line is coupled to the second voltage source;
a capacitor disposed between the first transistor and the second transistor;
the first light emitting diode and the second light emitting diode are arranged on the transmission line on the third side of the second transistor in series, and the third transistor and the fourth transistor are arranged on the transmission line on the fourth side of the second transistor in series.
7. The LED driver circuit arrangement according to claim 6, wherein the channel width of the second transistor is 1-10 times the channel width of the first transistor.
8. The LED driver circuit arrangement according to claim 6, wherein the channel width of the first transistor is between 3w and 30w, and the channel width of the second transistor is between 30w and 300 w.
9. The light emitting diode driver circuit arrangement of claim 6, further comprising a third transistor disposed between the second transistor and the transmission line on the third side of the second transistor, a first side of the third transistor being coupled to a second signal line and a third voltage source, a second side of the third transistor opposite to the first side being coupled to the transmission line.
10. The led driver circuit arrangement of claim 8, wherein said second transistor has a channel width that is approximately 2 times a channel width of said third transistor.
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| Application Number | Priority Date | Filing Date | Title |
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| TW110140375A TWI776720B (en) | 2021-10-29 | 2021-10-29 | Light emitting diode driving circuit and layout of light emitting diode driving circuit |
| TW110140375 | 2021-10-29 |
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| CN114373422A true CN114373422A (en) | 2022-04-19 |
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Also Published As
| Publication number | Publication date |
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| TW202318370A (en) | 2023-05-01 |
| CN114373422B (en) | 2023-12-19 |
| TWI776720B (en) | 2022-09-01 |
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