CN210443247U - LED drive circuit and liquid crystal display device - Google Patents
LED drive circuit and liquid crystal display device Download PDFInfo
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- CN210443247U CN210443247U CN201921634259.6U CN201921634259U CN210443247U CN 210443247 U CN210443247 U CN 210443247U CN 201921634259 U CN201921634259 U CN 201921634259U CN 210443247 U CN210443247 U CN 210443247U
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Abstract
The utility model provides a LED drive circuit and liquid crystal display device, LED drive circuit's constant current drive module includes a plurality of sub constant current drive modules, and every sub constant current drive module includes that resistance selects module, current mirror module and adjusts luminance controllable module. The resistance selection module is used for receiving the visual angle mode signal and providing different impedances; the first end of the current mirror module is connected with the resistance selection module to obtain reference current according to the impedance, and the second end of the current mirror module generates bias current according to the reference current and generates bias voltage through a bias resistor; the input control end of the dimming controllable module is connected with the second end of the current mirror module, and the access connection end of the dimming controllable module is connected with a corresponding current channel in the plurality of current channels and provides a channel current. The utility model discloses a plurality of sub constant current drive module of accessible provide corresponding a set of channel current according to visual angle mode signal, have the advantage of saving the cost, raising the efficiency.
Description
Technical Field
The utility model belongs to the technical field of the display, a LED drive circuit and liquid crystal display device is related to.
Background
For the liquid crystal display device with wide and narrow viewing angles, the currently used backlight may be, for example, that the brightness of the middle longitudinal region is high and the brightness is gradually reduced towards the two sides to achieve the display effect with narrow viewing angles, then the LED driving circuit needs to provide two sets of channel currents for the LED lamp set to emit light and correspondingly switch according to the viewing angle mode, and the magnitudes of the channel currents of each set of channel currents are different. However, the conventional LED driving circuit can only provide one set of channel currents without the switching function, and the magnitude of each channel current of the set of channel currents is the same. Fig. 1 is a circuit diagram of a constant current driving module of a conventional LED driving circuit. As shown in fig. 1, the constant current driving module includes a current mirror module and a plurality of dimming controllable modules connected to the current mirror module, the current mirror module is grounded at a first end through a resistor and outputs a bias voltage at a second end, and the plurality of dimming controllable modules provide a set of channel currents to the LED lamp set according to the bias voltage.
Therefore, in order to adapt to a wide and narrow viewing angle lcd, the LED driving circuit needs to be improved, for example, a control chip (MCU), a single-stage boost chip and a programmable LED driving chip are disposed on a circuit board, and a plurality of peripheral circuits are collocated, which may result in higher manufacturing cost; moreover, after the circuit board is manufactured, the control chip code needs to be written, and the collocation of software and hardware needs to be verified, but a lot of time is consumed.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present invention is directed to an LED driving circuit and a liquid crystal display device to solve the problems of high cost and time consumption of the above improved technical solution.
An embodiment of the utility model provides a LED drive circuit, LED drive circuit includes constant current drive module, constant current drive module includes a plurality of sub-constant current drive modules, a plurality of sub-constant current drive modules link to each other one by one with a plurality of current channels and be used for providing a plurality of channel currents that the current value is not identical for the LED banks, each sub-constant current drive module of a plurality of sub-constant current drive modules includes a resistance selection module, a current mirror module and a controllable module of adjusting luminance, the resistance selection module is used for receiving visual angle mode signal, and provides different impedances according to visual angle mode signal; the current mirror module comprises a first end and a second end, the first end of the current mirror module is connected with the resistance selection module to obtain reference current according to the impedance, and the second end of the current mirror module generates bias current according to the reference current and generates bias voltage through a bias resistor; the dimming controllable module comprises an input control end and a path connecting end, the input control end of the dimming controllable module is connected with the second end of the current mirror module, the path connecting end of the dimming controllable module is connected with a corresponding current channel in the plurality of current channels, and the dimming controllable module is used for providing a channel current at the path connecting end of the dimming controllable module according to the bias voltage.
Further, the impedances provided by the plurality of resistance selection modules of the plurality of sub constant current driving modules according to the viewing angle mode signals are not completely the same.
Furthermore, the current mirror module and the dimming controllable module are both arranged on a chip, the chip comprises a plurality of current setting ends, and the resistance selection module is connected with the first end of the current mirror module through the corresponding current setting end.
Further, the resistance selection module includes a first resistance, a first switch element and a second resistance, a first end of the first resistance is connected to the current setting end, a second end of the first resistance is grounded, the first switch element includes a first control end, a first path end and a second path end, the first control end of the first switch element receives the view mode signal, the first path end of the first switch element is connected to the first end of the first resistance, the second path end of the first switch element is connected to the first end of the second resistance, and the second end of the second resistance is grounded.
Furthermore, the current mirror module and the dimming controllable module are both arranged on a chip, and the chip comprises a plurality of current setting ends and a view angle mode control end for receiving the view angle mode signal; the resistance selection module comprises a first resistor, a first switch element and a second resistor, wherein the first resistor is arranged outside the chip, the first switch element and the second resistor are arranged on the chip, the first end of the first resistor is connected with the first end of the current mirror module through a corresponding current setting end, the second end of the first resistor is grounded, the first switch element comprises a first control end, a first path end and a second path end, the first control end of the first switch element is connected with the view angle mode control end, the first path end of the first switch element is connected with the first end of the current mirror module, the second path end of the first switch element is connected with the first end of the second resistor, and the second end of the second resistor is grounded.
Further, the current mirror module includes a second switching element, a third switching element, a fourth switching element, and a first amplifier; the second switch element comprises a second control end, a third path end and a fourth path end, the second control end of the second switch element is connected with the fourth path end of the second switch element, and the third path end of the second switch element receives a first voltage; the third switching element comprises a third control end, a fifth pass end and a sixth pass end, the third control end of the third switching element is connected with the second control end of the second switching element, the fifth pass end of the third switching element is connected with the third end of the second switching element, and the sixth pass end of the third switching element is the second end of the current mirror module; the fourth switching element comprises a fourth control end, a seventh path end and an eighth path end, the seventh path end of the fourth switching element is connected with the fourth path end of the second switching element, and the eighth path end of the fourth switching element is the first end of the current mirror module; the first amplifier comprises a first positive phase input end, a first negative phase input end and a first output end, the first positive phase input end of the first amplifier receives a second voltage, the first negative phase input end of the first amplifier is connected with the eighth path end of the fourth switching element, and the first output end of the first amplifier is connected with the fourth control end of the fourth switching element.
Further, the second switching element and the third switching element are both PMOS transistors, and the fourth switching element is an NMOS transistor.
Further, the dimming controllable module comprises a second amplifier, a fifth switching element and a third resistor, the second amplifier comprises a second positive phase input terminal, a second negative phase input terminal and a second output terminal, and the second positive phase input terminal of the second amplifier is an input control terminal of the dimming controllable module; the fifth switching element comprises a fifth control end, a ninth path end and a tenth path end, the fifth control end of the fifth switching element is connected with the second output end of the second amplifier, the ninth path end of the fifth switching element is a path connection end of the dimming controllable module, and the tenth path end of the fifth switching element is connected with the second inverting input end of the second amplifier; a first end of the third resistor is connected to the tenth path end of the fifth switching element, and a second end of the third resistor is grounded.
Further, the LED driving circuit includes a PWM control module, the second amplifier includes a power supply terminal, and the power supply terminal of the second amplifier is connected to the PWM control module to receive the PWM signal.
The embodiment of the utility model provides a still provide a liquid crystal display device, a serial communication port, including foretell LED drive circuit for it is backlight that the drive LED banks produces.
The utility model provides a LED drive circuit and liquid crystal display device, a plurality of sub constant current drive module of accessible provide corresponding a set of channel current according to visual angle mode signal, applicable in the many visual angle mode for example the demonstration of wide and narrow visual angle mode, have the advantage of saving the cost, raising the efficiency to the competitiveness of product has been promoted and customer satisfaction has been increased.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a circuit diagram of a constant current driving module of a conventional LED driving circuit.
Fig. 2 is a circuit connection diagram of an LED driving circuit according to a first embodiment of the present invention.
Fig. 3 is a circuit diagram of an LED driving circuit according to a second embodiment of the present invention.
Fig. 4 is a circuit diagram of an LED driving circuit according to a third embodiment of the present invention.
Fig. 5 is a circuit diagram of an LED driving circuit according to a fourth embodiment of the present invention.
Fig. 6 is a circuit connection diagram of an LED driving circuit according to a fifth embodiment of the present invention.
Detailed Description
To further illustrate the technical means and effects of the present invention adopted to achieve the intended purpose, the following detailed description will be given to specific embodiments, methods, steps, structures, features and effects of the LED driving circuit and the liquid crystal display device according to the present invention, with reference to the accompanying drawings and preferred embodiments.
The foregoing and other features, aspects and utilities of the present invention will be apparent from the following more particular description of the preferred embodiments, as illustrated in the accompanying drawings. While the present invention has been described with reference to the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
First embodiment
Fig. 2 is a circuit connection diagram of an LED driving circuit according to a first embodiment of the present invention. The present embodiment provides an LED driving circuit, as shown in fig. 2, the LED driving circuit includes a constant current driving module, the constant current driving module includes a plurality of sub-constant current driving modules, the plurality of sub-constant current driving modules are connected to a plurality of current channels (as shown by LED1.. LEDn in fig. 2) one by one to provide a plurality of channel currents with different current values for an LED lamp set, each sub-constant current driving module of the plurality of sub-constant current driving modules includes a resistor selecting module 100, a current mirror module 200 and a dimming controllable module 300, the resistor selecting module 100 is configured to receive a viewing angle mode signal Vk and provide different impedances according to the viewing angle mode signal Vk; the current mirror module 200 includes a first terminal and a second terminal, the first terminal of the current mirror module 200 is connected to the resistance selection module 100 to obtain a reference current according to the impedance, and the second terminal of the current mirror module 200 generates a bias current according to the reference current and generates a bias voltage through a bias resistor Rf; the dimming controllable module 300 comprises an input control terminal and a path connection terminal, the input control terminal of the dimming controllable module 300 is connected to the second terminal of the current mirror module 200, the path connection terminal of the dimming controllable module 300 is connected to a corresponding current channel of the plurality of current channels, and the dimming controllable module 300 is configured to provide a channel current at the path connection terminal of the dimming controllable module 300 according to the bias voltage.
In the present embodiment, the viewing angle mode signal Vk includes the first viewing angle mode signal Vk1 and the second viewing angle mode signal Vk2, but the present embodiment is not limited thereto, and the viewing angle mode signal Vk may further include, for example, the third viewing angle mode signal Vk3, and the like.
Specifically, the constant current driving module of this embodiment includes a plurality of sub constant current driving modules, and when the constant current driving module receives the view mode signal Vk, each sub constant current driving module receives the view mode signal Vk and drives according to the view mode signal Vk. Each sub constant current driving module is described below by taking the first sub constant current driving module as an example, the resistance selection module 100 in the first sub constant current driving module provides different impedances according to the received viewing angle mode signal Vk, for example, the resistance selection module 100 may provide a corresponding first impedance when the viewing angle mode signal Vk is the first viewing angle mode signal Vk1, and the resistance selection module 100 may provide a corresponding second impedance when the viewing angle mode signal Vk is the second viewing angle mode signal Vk 2.
Meanwhile, the current mirror module 200 is a standard component commonly existing in analog integrated circuits, and in the design of a conventional voltage mode operational amplifier, the current mirror module 200 is usually used for generating a bias current and serving as an active load, and may be composed of two or more parallel-connected related current branches, and the current of each branch is proportional according to a certain device proportion relation. In this embodiment, the current mirror module 200 is configured to generate a reference current according to the impedance connected to the first terminal thereof, generate a bias current having a fixed proportional relationship with the reference current at the second terminal thereof, and generate a bias voltage through a bias resistor Rf (for example, the first terminal of the bias resistor Rf is connected to the second terminal of the current mirror module 200, and the second terminal of the bias resistor Rf is grounded). In this embodiment, the resistance values of the bias resistors Rf in each sub constant current driving module are not limited, and may be set to be the same or different, for example. Therefore, the current mirror module 200 in each sub constant current driving module of the present embodiment may generate a corresponding bias voltage according to the impedance provided by the connected resistance selection module 100. For example, in the nth sub constant current driving module, when the view mode signal Vk is the first view mode signal Vk1, the first terminal of the current mirror module 200 may generate a reference current according to the first impedance provided by the connected resistor selection module 100 to be set as an nth 1 reference current, enable the second terminal to generate a bias current to be set as an nth 1 bias current, and obtain a bias voltage through the bias resistor Rf to be set as an nth 1 bias voltage; when the view mode signal Vk is the second view mode signal Vk2, the first terminal of the current mirror module 200 may generate a reference current according to the second impedance provided by the connected resistor selection module 100 to be set as the n-th 2 reference current, cause the second terminal to generate a bias current to be set as the n-th 2 bias current, and obtain a bias voltage through the bias resistor Rf to be set as the n-th 2 bias voltage.
Then, the second terminal of the current mirror module 200 is connected to the input control terminal of the dimming controllable module 300, and the dimming controllable module 300 can adjust the channel current at the path connection terminal connected to the current channel according to the voltage of the bias voltage at the input control terminal. For example, in the nth sub constant current driving module, when the view mode signal Vk is the first view mode signal Vk1, the second terminal of the current mirror module 200 obtains the bias voltage to be the nth 1 bias voltage, and the dimming controllable module 300 may adjust the channel current at the channel connection terminal connected to the current channel LEDn according to the voltage of the nth 1 bias voltage at the input control terminal; when the view mode signal Vk is the second view mode signal Vk2, the second terminal of the current mirror module 200 obtains the bias voltage to be the n2 th bias voltage, and the dimming controllable module 300 can adjust the channel current at the channel connection terminal connected to the current channel according to the voltage of the n2 th bias voltage at the input control terminal.
Therefore, each sub-constant current driving module of the embodiment can provide corresponding channel current according to a view angle mode signal Vk, and then transmits the channel current to the LED lamp set through the channel circuit. And because the resistance selection module 100 provides different impedances according to the view mode signal Vk, that is, the impedances received by the current mirror modules 200 at the first ends thereof in the same sub constant current driving module in different view modes are different, the reference currents generated at the first terminals of the current mirror modules 200 are different, so that the bias currents at the second terminals thereof are different to obtain two bias voltages, and accordingly the dimming controllable module 300 outputs channel currents with different current magnitudes, a corresponding set of channel currents may be provided by the plurality of sub constant current driving modules according to the view angle mode signal Vk, for example, when the view mode signal Vk is the first view mode signal Vk1, the plurality of sub constant current driving modules provide a first set of channel currents, when the view mode signal Vk is the second view mode signal Vk2, the plurality of sub constant current driving modules provide a second set of channel currents. Thus, the LED driving circuit of the present embodiment can be applied to display in a multi-view mode, for example, display in a wide view angle mode and display in a narrow view angle mode.
In an embodiment, the impedances provided by the plurality of resistor selection modules 100 of the plurality of sub-constant current driving modules according to the view mode signal Vk may not be completely the same, for example, the nth resistor selection module 100 in the nth sub-constant current driving module in fig. 2 may select a corresponding impedance in a group of resistors in trapezoidal symmetrical distribution according to a view mode signal Vk (e.g., the narrow view mode signal Vk), that is, the resistance of the middle impedance is the smallest, and the resistances of the front and rear sides of the resistor selection module increase as the distance from the middle impedance increases, so that the channel current on the channel connection terminal of the dimming controllable module 300 connected to the current channel LEDn is distributed in a corresponding trapezoidal shape, thereby driving the LED lamp group to emit backlight in a trapezoidal symmetrical distribution, and improving the display effect of the corresponding view mode (e.g., the narrow view mode).
The LED driving circuit of this embodiment can provide a corresponding set of channel currents according to the view angle mode signal Vk through the plurality of sub constant current driving modules, and is applicable to display in a multi-view angle mode, such as a wide-and-narrow-view angle mode, and has the advantages of saving cost and improving efficiency, and improves competitiveness and customer satisfaction of products.
Second embodiment
Fig. 3 is a circuit connection diagram of an LED driving circuit according to a second embodiment of the present invention. The LED driving circuit shown in fig. 3 has substantially the same structure as the LED driving circuit shown in fig. 2, except that: the current mirror module 200 and the dimming controllable module 300 are both disposed on a chip, the chip includes a plurality of current setting terminals (see, e.g., iset1.. ISETn in fig. 3), and the resistance selection module 100 is connected to the first terminal of the current mirror module 200 through the corresponding current setting terminals (IEST1, …, ISETn, …).
In one embodiment, the resistance selection module 100 includes a first resistor R1, a first switch element T1, and a second resistor R2, a first terminal of the first resistor R1 is connected to a current setting terminal (IEST1, …, ISETn, …), a second terminal of the first resistor R1 is connected to ground, the first switch element T1 includes a first control terminal, a first pass terminal, and a second pass terminal, the first control terminal of the first switch element T1 is connected to the viewing angle mode signal Vk, the first pass terminal of the first switch element T1 is connected to a first terminal of the first resistor R1, the second pass terminal of the first switch element T1 is connected to a first terminal of the second resistor R2, and the second terminal of the second resistor R2 is connected to ground.
In one embodiment, the first switching element T1 may be, but is not limited to, an NMOS transistor, an N-type transistor, a PMOS transistor, a P-type transistor, or the like.
The operation of the resistor selection module 100 is illustrated below with the first view mode signal Vk1 being low and the second view mode signal Vk2 being high, the first switch element T1 being an NMOS transistor. When the viewing angle mode signal Vk is the first viewing angle mode signal Vk1, the control terminal of the first switch element T1 receives the viewing angle mode signal Vk and is at a low level, the first switch element T1 is in an off state, such that the first terminal of the second resistor R2 cannot be connected to the first terminal of the first resistor R1 through the first switch, and the first terminal of the first resistor R1 can be connected to the first terminal of the current mirror module 200 through the current setting terminal (IEST1, …, ISETn, …), such that the first terminal of the current mirror module 200 is electrically connected to only the first resistor R1, i.e., the resistance provided by the resistance selection module 100 is only the first resistor R1, such that the first terminal of the current mirror outputs the first reference current according to the electrically connected resistance, i.e., the first resistor R1. When the view mode signal Vk is the second view mode signal Vk2, the control terminal of the first switch element T1 receives the second view mode signal Vk2 and is at a high level, the first switch element T1 is in a conducting state, such that the first terminal of the second resistor R2 can be electrically connected to the first terminal of the first resistor R1 through the first switch, and the first terminal of the first resistor R1 is electrically connected to the first terminal of the current mirror module 200 through the current setting terminal (IEST1, …, ISETn, …), such that the first terminal of the current mirror module 200 is electrically connected to the first resistor R1 and the second resistor R2, respectively, i.e., the resistance provided by the resistance selection module 100 is the parallel connection of the first resistor R1 and the second resistor R2, such that the first terminal of the current mirror outputs the second reference current according to the electrically connected resistance, i.e., the parallel connection of the first resistor R1 and the second resistor R2.
In an embodiment, the impedances provided by the plurality of resistor selection modules 100 of the plurality of sub constant current driving modules according to the view mode signal Vk may not be completely the same, for example, the corresponding first resistors R1 in the plurality of sub constant current driving modules in fig. 3 may select the same resistance value or different resistance values according to the requirement of the corresponding view mode, and similarly, the corresponding second resistors R2 in the plurality of sub constant current driving modules may also select the same resistance value or different resistance values according to the requirement of the corresponding view mode.
The LED drive circuit of the embodiment can provide a corresponding group of channel currents according to the view angle mode signal Vk through the plurality of sub constant current drive modules only by building the resistor selection module 100 on the periphery of the chip, is applicable to display in a multi-view angle mode such as a wide-narrow view angle mode, has the advantages of saving cost and improving efficiency, and improves the competitiveness of products and customer satisfaction.
Third embodiment
Fig. 4 is a circuit connection diagram of an LED driving circuit according to a third embodiment of the present invention. The LED driving circuit shown in fig. 4 has substantially the same structure as the LED driving circuit shown in fig. 2, except that: the current mirror module 200 and the dimming controllable module 300 are both disposed on a chip, and the chip includes a plurality of current setting terminals (as shown in fig. 4 as iset1.. ISETn) and a view MODE control terminal MODE for receiving a view MODE signal Vk; the resistance selection module 100 includes a first resistor R1, a first switch element T1, and a second resistor R2, the first resistor R1 is disposed outside the chip, the first switch element T1 and the second resistor R2 are disposed on the chip, a first end of the first resistor R1 is connected to a first end of the current mirror module 200 through corresponding current setting terminals (IEST1, …, ISETn, …), a second end of the first resistor R1 is grounded, the first switch element T1 includes a first control terminal, a first pass terminal, and a second pass terminal, the first control terminal of the first switch element T1 is connected to the view MODE control terminal MODE, the first pass terminal of the first switch element T1 is connected to the first end of the current mirror module 200, the second pass terminal of the first switch element T1 is connected to the first terminal of the second resistor R2, and the second terminal of the second resistor R2 is grounded.
In one embodiment, the first switching element T1 may be, but is not limited to, an NMOS transistor, an N-type transistor, a PMOS transistor, a P-type transistor, or the like.
The operation of the resistor selection module 100 is illustrated below with the first view mode signal Vk1 being low and the second view mode signal Vk2 being high, the first switch element T1 being an NMOS transistor. When the view MODE signal Vk is the first view MODE signal Vk1, the control terminal of the first switch element T1 receives the first view MODE signal Vk1 through the view MODE control terminal MODE of the chip and is at a low level, the first switch element T1 is in an off state, such that the first terminal of the second resistor R2 cannot be electrically connected to the first terminal of the current mirror module 200 through the first switch, and the first terminal of the first resistor R1 can be connected to the first terminal of the current mirror module 200 through the current setting terminal (IEST1, …, ISETn, …), and the first terminal of the current mirror module 200 is electrically connected to only the first resistor R1, i.e., the resistance provided by the resistance selection module 100 is only the first resistor R1, such that the first terminal of the current mirror outputs the first reference current according to the electrically connected resistance, i.e., the first resistor R1. When the view MODE signal Vk is the second view MODE signal Vk2, the control terminal of the first switching element T1 receives the second view MODE signal Vk2 through the view MODE control terminal MODE of the chip to be at a high level, the first switch element T1 is turned on, so that the first terminal of the second resistor R2 can be electrically connected to the first terminal of the current mirror module 200 through the first switch, the first terminal of the first resistor R1 can be electrically connected to the first terminal of the current mirror module 200 through a current setting terminal (IEST1, …, ISETn, …), the first end of the current mirror module 200 is electrically connected to the first resistor R1 and the second resistor R2 respectively, that is, the resistance provided by the resistance selection module 100 is the parallel resistance of the first resistor R1 and the second resistor R2, so that the first end of the current mirror outputs the second reference current according to the electrically connected impedance, i.e. the parallel resistance of the first resistor R1 and the second resistor R2.
The LED driving circuit of this embodiment, only need to build the partial resistance of resistance selection module 100 in the periphery of the chip, just can adjust the size of this partial resistance according to the needs of visual angle mode, so as to obtain the electric current that the LED banks needs, and the chip can receive visual angle mode signal Vk, and a plurality of sub constant current driving modules of accessible provide a corresponding set of channel current according to visual angle mode signal Vk, applicable in the display of many visual angle modes such as wide and narrow visual angle mode, have the advantage of saving cost, raise the efficiency, and promoted the competitiveness of product and increased customer satisfaction.
Fourth embodiment
Fig. 5 is a circuit connection diagram of an LED driving circuit according to a fourth embodiment of the present invention. The LED driving circuit shown in fig. 5 has substantially the same structure as the LED driving circuit shown in fig. 2, except that: the current mirror module 200 includes a second switching element T2, a third switching element T3, a fourth switching element T4, and a first amplifier a 1; the second switching element T2 includes a second control terminal, a third path terminal and a fourth path terminal, the second control terminal of the second switching element T2 is connected to the fourth path terminal of the second switching element T2, and the third path terminal of the second switching element T2 receives the first voltage; the third switching element T3 includes a third control terminal, a fifth path terminal and a sixth path terminal, the third control terminal of the third switching element T3 is connected to the second control terminal of the second switching element T2, the fifth path terminal of the third switching element T3 is connected to the third terminal of the second switching element T2, and the sixth path terminal of the third switching element T3 is the second terminal of the current mirror module 200; the fourth switching element T4 includes a fourth control terminal, a seventh path terminal and an eighth path terminal, the seventh path terminal of the fourth switching element T4 is connected to the fourth path terminal of the second switching element T2, and the eighth path terminal of the fourth switching element T4 is the first terminal of the current mirror module 200; the first amplifier a1 includes a first non-inverting input terminal, a first inverting input terminal, and a first output terminal, the first non-inverting input terminal of the first amplifier a1 receives the second voltage, the first inverting input terminal of the first amplifier a1 is connected to the eighth path terminal of the fourth switching element T4, and the first output terminal of the first amplifier a1 is connected to the fourth control terminal of the fourth switching element T4.
In an embodiment, the second switching element T2 and the third switching element T3 may both be PMOS transistors, the fourth switching element T4 may be NMOS transistors, and so on. However, the present invention is not limited thereto, the second switching element T2 and the third switching element T3 may both be P-type transistors, and the fourth switching element T4 may be N-type transistors, etc.
Specifically, the first non-inverting input terminal of the first amplifier a1 in the current mirror module 200 of the present embodiment receives the second voltage, the first inverting input terminal of the first amplifier a1 is connected to the eighth path terminal of the fourth switching element T4, and the first output terminal of the first amplifier a1 is connected to the fourth control terminal of the fourth switching element T4, so that the first amplifier a1 and the fourth switching element T4 are connected in a negative feedback circuit. If the impedance provided by the resistance selection module 100 according to the view mode signal Vk is connected to the first inverting input terminal of the first amplifier a1, initially, the inverting input terminal of the first amplifier a1 is connected to the impedance provided by the resistance selection module 100 and the voltage is zero, and the voltage at the non-inverting input terminal of the first amplifier a1 is the second voltage, then the voltage at the non-inverting input terminal of the first amplifier a1 is greater than the voltage at the inverting input terminal, the first amplifier a1 outputs an amplified positive voltage, so that the fourth switching element T4 is turned on, and the second control terminal of the second switching element T2 and the third control terminal of the third switching element T3 can both be connected to the impedance provided by the resistance selection module 100 through the fourth switching element T4 and be at a low level, so that the second switching element T2 and the fourth switching element T4 are both in a conductive state. Thus, the impedance provided by the resistance selection module 100 may receive the first voltage at the third path terminal of the second switching element T2 through the turned-on fourth switching element T4 and the turned-on second switching element T2, and the fourth path terminal of the second switching element T2 may output a corresponding current, and the fourth path terminal of the fourth switching element T4 may output a corresponding current, so that the voltage at the inverting input terminal of the first amplifier a1 is increased, and at the same time, the voltage difference between the non-inverting input terminal and the inverting input terminal of the first amplifier 1 is also decreased, so that the voltage at the first output terminal of the first amplifier a1 is decreased, and the current at the eighth path terminal is correspondingly decreased by the fourth switching element T4 according to the decrease of the voltage at the fourth control terminal thereof. Accordingly, the eighth path terminal of the fourth switching element T4 can stably output a reference current according to the impedance provided by the resistance selection unit. According to the operation characteristic of the current mirror, when a current is output from the fourth path terminal of the second switching element T2, a current, i.e., a bias current, is output from the sixth path terminal of the third switching element T3. Therefore, the current mirror module 200 may generate a bias voltage through a bias resistor Rf, and the dimming controllable module 300 may provide a channel current at the pass connection terminal of the dimming controllable module 300 according to the bias voltage.
In the LED driving circuit of this embodiment, the plurality of current mirror modules 200 in the plurality of sub constant current driving modules may generate different reference currents according to the resistances provided by the connected resistance selection module 100 under different viewing angle mode signals Vk, and may be used for the LED driving circuit to provide a corresponding set of channel currents according to the viewing angle mode signals Vk.
Fifth embodiment
Fig. 6 is a circuit connection diagram of an LED driving circuit according to a fifth embodiment of the present invention. The LED driving circuit shown in fig. 6 has substantially the same structure as the LED driving circuit shown in fig. 2, except that: the dimming controllable module 300 includes a second amplifier a2, a fifth switching element T5 and a third resistor R3, the second amplifier a2 includes a second non-inverting input terminal, a second inverting input terminal and a second output terminal, and the second non-inverting input terminal of the second amplifier a2 is an input control terminal of the dimming controllable module 300; the fifth switching element T5 includes a fifth control terminal, a ninth path terminal and a tenth path terminal, the fifth control terminal of the fifth switching element T5 is connected to the second output terminal of the second amplifier a2, the ninth path terminal of the fifth switching element T5 is a path connection terminal of the dimming controllable module 300, and the tenth path terminal of the fifth switching element T5 is connected to the second inverting input terminal of the second amplifier a 2; a first terminal of the third resistor R3 is connected to the tenth path terminal of the fifth switching element T5, and a second terminal of the third resistor R3 is grounded.
In one embodiment, the LED driving circuit includes a PWM control module 400, the second amplifier a2 includes a power supply terminal, and the power supply terminal of the second amplifier a2 is coupled to the PWM control module 400 to receive the PWM signal. The second amplifier a2 may make the voltage output from the second output terminal of the second amplifier a2 equivalent to the product of the initial output voltage and the duty ratio of the PWM signal according to the duty ratio of the PWM signal, and the channel current at the ninth path terminal of the fifth switching element T5 equivalent to the product of the initial output current and the duty ratio of the PWM signal, so that the current drawn by the LED lamp set from the current channel is adjusted, and thus, the LED lamp set may display backlight according to the adjusted channel current.
Specifically, the non-inverting input terminal of the second amplifier a2 of the present embodiment receives the bias voltage at the second terminal of the current mirror, the inverting input terminal of the second amplifier a2 is connected to the tenth path terminal of the fifth switching element T5, and the inverting input terminal of the second amplifier a2 may be grounded through the third resistor R3, so that the second amplifier a2 may receive the feedback voltage at the first terminal of the third resistor R3. In this embodiment, the voltage amplified by the voltage difference between the non-inverting input terminal and the inverting input terminal of the second amplifier a2 may make the fifth switch element T5 turn on accordingly, so that the tenth path terminal outputs a corresponding current. When the current output from the tenth path terminal of the fifth switching element T5 increases, the feedback voltage at the first terminal of the third resistor R3 increases, so that the voltage amplified by the voltage difference between the non-inverting input terminal and the inverting input terminal of the second amplifier a2 decreases, and the current output from the tenth path terminal of the fifth switching element T5 decreases. Therefore, when the second amplifier a2 receives the bias voltage in the view mode, the tenth path of the fifth switch element T5 outputs a stable current, and the ninth path thereof can provide a stable current, i.e., the channel current.
In the LED driving circuit of this embodiment, different reference currents are generated by the plurality of dimming controllable modules 300 in the plurality of sub constant current driving modules according to the bias voltages obtained by the connected current mirror modules 200 in different viewing angle modes, so that the LED driving circuit can provide a corresponding set of channel currents according to the viewing angle mode signal Vk.
Sixth embodiment
The embodiment of the utility model provides a still based on same utility model conceive, provide a liquid crystal display device, this liquid crystal display device includes foretell LED drive circuit, and drive LED banks produces backlight. For the specific implementation of this embodiment, reference may be made to the implementation of the LED driving circuit described above, and details are not described here.
The utility model provides a liquid crystal display device, a plurality of sub constant current drive module of accessible LED drive circuit provide corresponding a set of channel current according to visual angle mode signal, applicable in the many visual angle mode for example the demonstration of wide and narrow visual angle mode, have the advantage of saving the cost, raising the efficiency to the competitiveness of product has been promoted and customer satisfaction has been increased.
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments, and although the present invention has been disclosed with the preferred embodiments, but the present invention is not limited to the above embodiments, and any person skilled in the art can make some changes or modifications to the equivalent embodiments without departing from the technical scope of the present invention.
Claims (10)
1. The LED driving circuit is characterized by comprising a constant current driving module, wherein the constant current driving module comprises a plurality of sub constant current driving modules, the plurality of sub constant current driving modules are connected with a plurality of current channels one by one and used for providing a plurality of channel currents with incompletely same current values for an LED lamp set, and each sub constant current driving module of the plurality of sub constant current driving modules comprises:
a resistance selection module (100), the resistance selection module (100) being configured to receive a view mode signal (Vk) and to provide different impedances in accordance with the view mode signal (Vk);
the current mirror module (200), the current mirror module (200) comprises a first end and a second end, the first end of the current mirror module (200) is connected with the resistance selection module (100) to obtain a reference current according to the impedance, and the second end of the current mirror module (200) generates a bias current according to the reference current and generates a bias voltage through a bias resistor (Rf);
a dimming controllable module (300), wherein the dimming controllable module (300) comprises an input control terminal and a path connection terminal, the input control terminal of the dimming controllable module (300) is connected to the second terminal of the current mirror module (200), the path connection terminal of the dimming controllable module (300) is connected to a corresponding current channel of the plurality of current channels, and the dimming controllable module (300) is configured to provide a channel current at the path connection terminal of the dimming controllable module (300) according to the bias voltage.
2. The LED driving circuit according to claim 1, wherein the impedances provided by the plurality of resistance selection modules (100) of the plurality of sub constant current driving modules according to the view angle mode signal (Vk) are not identical.
3. The LED driver circuit according to claim 1, wherein the current mirror module (200) and the dimming controllable module (300) are both arranged on a chip, the chip comprising a plurality of current setting terminals (IEST1, …, ISETn, …), the resistance selection module (100) being connected to the first terminal of the current mirror module (200) via corresponding current setting terminals (IEST1, …, ISETn, …).
4. The LED driver circuit according to claim 3, wherein the resistance selection module (100) comprises a first resistor (R1), a first switching element (T1) and a second resistor (R2), a first terminal of the first resistor (R1) is connected to the current set terminal (IEST1, …, ISETn, …), a second terminal of the first resistor (R1) is grounded, the first switching element (T1) includes a first control terminal, a first path terminal and a second path terminal, a first control terminal of the first switching element (T1) receives the view mode signal (Vk), a first path terminal of the first switching element (T1) is connected to a first terminal of the first resistor (R1), the second path terminal of the first switching element (T1) is connected to the first terminal of the second resistor (R2), and the second terminal of the second resistor (R2) is grounded.
5. The LED driving circuit according to claim 1, wherein the current mirror module (200) and the dimming controllable module (300) are both provided on a chip comprising a plurality of current setting terminals (IEST1, …, ISETn, …) and a view MODE control terminal (MODE) for receiving the view MODE signal (Vk);
the resistance selection module (100) comprises a first resistor (R1), a first switching element (T1) and a second resistor (R2), the first resistor (R1) is arranged outside the chip, the first switching element (T1) and the second resistor (R2) are arranged on the chip, a first end of the first resistor (R1) is connected to a first end of the current mirror module (200) through corresponding current setting terminals (IEST1, …, ISETn, …), a second end of the first resistor (R1) is grounded, the first switching element (T1) comprises a first control terminal, a first pass terminal and a second pass terminal, a first control terminal of the first switching element (T1) is connected to the view MODE control terminal (MODE), a first pass terminal of the first switching element (T1) is connected to a second terminal of the current mirror module (200), and a second pass terminal of the first switching element (T1) is connected to the second switch element (R2), a second terminal of the second resistor (R2) is connected to ground.
6. The LED driving circuit according to claim 1, wherein the current mirror module (200) comprises a second switching element (T2), a third switching element (T3), a fourth switching element (T4) and a first amplifier (a 1); the second switching element (T2) includes a second control terminal, a third path terminal and a fourth path terminal, the second control terminal of the second switching element (T2) is connected to the fourth path terminal of the second switching element (T2), the third path terminal of the second switching element (T2) receives a first voltage; the third switching element (T3) includes a third control terminal, a fifth pass terminal and a sixth pass terminal, the third control terminal of the third switching element (T3) is connected to the second control terminal of the second switching element (T2), the fifth pass terminal of the third switching element (T3) is connected to the third terminal of the second switching element (T2), and the sixth pass terminal of the third switching element (T3) is the second terminal of the current mirror module (200); the fourth switching element (T4) includes a fourth control terminal, a seventh path terminal and an eighth path terminal, the seventh path terminal of the fourth switching element (T4) is connected to the fourth path terminal of the second switching element (T2), the eighth path terminal of the fourth switching element (T4) is the first terminal of the current mirror module (200); the first amplifier (a1) includes a first non-inverting input terminal, a first inverting input terminal, and a first output terminal, the first non-inverting input terminal of the first amplifier (a1) receives the second voltage, the first inverting input terminal of the first amplifier (a1) is connected to the eighth pass terminal of the fourth switching element (T4), and the first output terminal of the first amplifier (a1) is connected to the fourth control terminal of the fourth switching element (T4).
7. The LED driving circuit according to claim 6, wherein the second switching element (T2) and the third switching element (T3) are both PMOS transistors, and the fourth switching element (T4) is an NMOS transistor.
8. The LED driving circuit according to claim 1, wherein the dimming controllable module (300) comprises a second amplifier (a2), a fifth switching element (T5) and a third resistor (R3), the second amplifier (a2) comprises a second non-inverting input terminal, a second inverting input terminal and a second output terminal, the second non-inverting input terminal of the second amplifier (a2) is the input control terminal of the dimming controllable module (300); the fifth switching element (T5) comprises a fifth control terminal, a ninth path terminal and a tenth path terminal, the fifth control terminal of the fifth switching element (T5) is connected to the second output terminal of the second amplifier (a2), the ninth path terminal of the fifth switching element (T5) is a path connection terminal of the dimming controllable module (300), and the tenth path terminal of the fifth switching element (T5) is connected to the second inverting input terminal of the second amplifier (a 2); a first terminal of the third resistor (R3) is connected to the tenth path terminal of the fifth switching element (T5), and a second terminal of the third resistor (R3) is grounded.
9. The LED driving circuit according to claim 8, wherein the LED driving circuit comprises a PWM control module (400), the second amplifier (A2) comprises a power supply terminal, and the power supply terminal of the second amplifier (A2) is connected to the PWM control module (400) to receive a PWM signal.
10. A liquid crystal display device comprising the LED driving circuit according to any one of claims 1 to 9 for driving the LED lamp set to generate backlight.
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| CN201921634259.6U CN210443247U (en) | 2019-09-27 | 2019-09-27 | LED drive circuit and liquid crystal display device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111654948A (en) * | 2020-06-12 | 2020-09-11 | 昆山龙腾光电股份有限公司 | LED driving circuit, driving method and display device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111654948A (en) * | 2020-06-12 | 2020-09-11 | 昆山龙腾光电股份有限公司 | LED driving circuit, driving method and display device |
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