CN218996330U - LED display effect improving circuit, LED driving chip and display device - Google Patents

Abstract

The application belongs to the technical field of display, and provides an LED display effect lifting circuit, an LED driving chip and a display device. The LED display effect improving circuit comprises a switch module and a selection module. One end of the switch module is electrically connected between the column driving circuit of the LED driving chip and the column scanning line of the LED array. The selection module is electrically connected with the other end of the switch module. The selection module outputs a clamp voltage signal or a pre-drive voltage signal to the switching module. When the column driving circuit of the LED driving chip is disconnected with the column scanning lines of the LED array, the selection module outputs clamping voltage signals or pre-driving voltage signals to the column scanning lines of the LED array through the switch module so as to perform shadow elimination, clamping or pre-driving on the column scanning lines of the LED array. The LED display effect improving circuit provided by the embodiment of the application can complete the shadow eliminating (clamping) and pre-driving functions, simplifies the circuit structure, saves the chip area and reduces the chip cost.

Description

LED display effect improving circuit, LED driving chip and display device

Technical Field

The application belongs to the technical field of display, and particularly relates to an LED display effect lifting circuit, an LED driving chip and a display device.

Background

In the current LED (Light-Emitting Diode) driving scheme, the switching of the corresponding LEDs is controlled by controlling the voltages of the positive and negative electrodes of the LEDs in the LED array, and the brightness of the LEDs is controlled by controlling the magnitude of the current flowing through the LEDs and the time of turning on. In an LED driving chip, in order to improve the display effect of an LED, a shadow eliminating circuit, a pre-driving circuit and a clamping circuit are usually disposed inside the chip, but these three circuits occupy a large chip area, resulting in waste of chip cost.

Disclosure of Invention

The embodiment of the application provides an LED display effect lifting circuit, an LED driving chip and a display device, which can solve the problem that the inside of the LED driving chip is provided with a shadow eliminating circuit, a pre-driving circuit and a clamping circuit which occupy a large chip area to cause chip cost waste.

In a first aspect, an embodiment of the present application provides an LED display effect enhancing circuit, including:

one end of the switch module is electrically connected between a column driving circuit of the LED driving chip and a column scanning line of the LED array;

the selection module is electrically connected with the other end of the switch module;

the selection module is used for outputting a clamping voltage signal or a pre-driving voltage signal to the switch module; when the column driving circuit of the LED driving chip is disconnected with the column scanning line of the LED array, the selecting module is used for outputting the clamping voltage signal or the pre-driving voltage signal to the column scanning line of the LED array through the switching module so as to perform shadow elimination, clamping or pre-driving on the column scanning line of the LED array.

Specifically, when the selection module is used for outputting a clamping voltage signal to the column scanning lines of the LED array through the switching module, a clamping (deghosting) mode is entered at this time to carry out deghosting and clamping on the column scanning lines of the LED array. The method and the device have the advantages that the shadow eliminating function is completed through the clamping voltage signal, and clamping is directly performed after the shadow eliminating function is completed. When the selection module is used for outputting a pre-driving voltage signal to the column scanning lines of the LED array through the switch module, the pre-driving mode is entered at the moment, and the column scanning lines of the LED array are pre-driven. The pre-driving function is completed through the pre-driving voltage signal.

The LED display effect lifting circuit provided by the embodiment of the application can complete three functions of shadow elimination (clamping) and pre-driving, simplifies a circuit structure, saves the area of an LED driving chip, and further reduces the cost of the LED driving chip.

In a possible implementation manner of the first aspect, the selection module includes a selection unit and a voltage follower unit; the voltage following unit is respectively and electrically connected with the other end of the switch module and the selection unit; the selection unit is used for outputting the clamping voltage signal or the pre-driving voltage signal to the voltage following unit; the voltage follower unit is used for providing driving capability of the clamping voltage signal or the pre-driving voltage signal;

the switch module is used for receiving a first control signal, and is used for being conducted according to the first control signal when the column driving circuit of the LED driving chip is disconnected with the column scanning line of the LED array;

the selection unit is used for receiving a second control signal, the clamping voltage signal and the pre-driving voltage signal, and outputting the clamping voltage signal to the column scanning line of the LED array through the voltage following unit when the second control signal is a first level signal so as to perform shadow elimination and clamping on the column scanning line of the LED array; when the second control signal is a second level signal, the selection unit is configured to output the pre-driving voltage signal to the column scanning line of the LED array through the voltage follower unit, so as to pre-drive the column scanning line of the LED array.

The selection unit is mainly used for outputting a clamping voltage signal or a pre-driving voltage signal according to the second control signal so as to complete different functions. The voltage follower unit is mainly used for providing driving capability of a clamping voltage signal or a pre-driving voltage signal.

In a possible implementation manner of the first aspect, the selection unit includes a selector; the selector is electrically connected with the voltage follower unit. The selector is mainly used for selecting corresponding voltage signals to output according to the second control signals. When the second control signal is the first level signal, the selector is used for outputting a clamping voltage signal. The selector is used for outputting a pre-driving voltage signal when the second control signal is a second level signal.

In a possible implementation manner of the first aspect, the voltage follower unit includes an operational amplifier; the non-inverting input end of the operational amplifier is electrically connected with the selection unit, and the inverting input end of the operational amplifier is electrically connected with the output end of the operational amplifier and the other end of the switch module respectively. The operational amplifier is mainly used for providing driving capability of clamping voltage signals or pre-driving voltage signals so as to complete the functions of shadow elimination (clamping) and pre-driving.

In a possible implementation manner of the first aspect, the switch module includes a first switch; one end of the first switch is electrically connected between the column driving circuit of the LED driving chip and the column scanning line of the LED array, and the other end of the first switch is electrically connected with one end of the selection module. The first switch is mainly used for controlling the on and off of the LED display effect lifting circuit. When the driving circuit of the LED driving chip is disconnected from the column scanning line of the LED array, the first switch is conducted according to the first control signal, so that the LED display effect improving circuit acts on the column scanning line of the LED array to improve the display effect of the LEDs. When the driving circuit of the LED driving chip acts on the column scanning line of the LED array, the first switch is disconnected according to the first control signal, so that the LED display effect improving circuit does not act on the column scanning line of the LED array any more, and the normal work of the LED driving chip is not influenced.

In a second aspect, an embodiment of the present application provides an LED driving chip, including:

the row driving circuits are used for being connected with a plurality of row scanning lines of the LED array in a one-to-one correspondence manner;

the plurality of column driving circuits are used for being correspondingly connected with a plurality of column scanning lines of the LED array one by one;

and a plurality of LED display effect enhancing circuits according to any one of the first aspects, wherein a plurality of the LED display effect enhancing circuits are correspondingly and electrically connected between a plurality of the column driving circuits and a plurality of column scanning lines of the LED array.

In a possible implementation manner of the second aspect, when the LED array is a common-cathode LED array, the row driving circuit includes a row switch; one end of the row switch is used for being electrically connected with a row scanning line of the LED array, and the other end of the row switch is grounded.

In a possible implementation manner of the second aspect, the column driving circuit includes a constant current source and a column switch; the input end of the constant current source is used for being electrically connected with a power supply, the output end of the constant current source is electrically connected with one end of the column switch, and the other end of the column switch is electrically connected with the LED display effect improving circuit and the column scanning line of the LED array respectively.

In a possible implementation manner of the second aspect, when the LED array is a common-anode LED array, the row driving circuit includes a row switch; one end of the row switch is used for being electrically connected with a power supply, and the other end of the row switch is used for being electrically connected with a row scanning line of the LED array;

the column driving circuit comprises a constant current source and a column switch; one end of the column switch is electrically connected with the LED display effect lifting circuit and the column scanning line of the LED array respectively, the other end of the column switch is electrically connected with the input end of the constant current source, and the output end of the constant current source is grounded.

In a third aspect, embodiments of the present application provide a display device including the LED driving chip of any one of the second aspects.

Compared with the prior art, the embodiment of the application has the beneficial effects that:

the embodiment of the application provides an LED display effect improving circuit, which comprises a switch module and a selection module. One end of the switch module is electrically connected between the column driving circuit of the LED driving chip and the column scanning line of the LED array. The selection module is electrically connected with the other end of the switch module. The selection module is used for outputting a clamping voltage signal or a pre-driving voltage signal to the switch module.

When the column driving circuit of the LED driving chip is disconnected with the column scanning line of the LED array, the selection module is used for outputting a clamping voltage signal or a pre-driving voltage signal to the column scanning line of the LED array through the switching module. When the selection module is used for outputting a clamping voltage signal to the column scanning lines of the LED array through the switch module, a clamping (shadow eliminating) mode is entered at the moment, and shadow eliminating and clamping are carried out on the column scanning lines of the LED array. The method and the device have the advantages that the shadow eliminating function is completed through the clamping voltage signal, and clamping is directly performed after the shadow eliminating function is completed.

When the selection module is used for outputting a pre-driving voltage signal to the column scanning lines of the LED array through the switch module, the pre-driving mode is entered at the moment, and the column scanning lines of the LED array are pre-driven. The pre-driving function is completed through the pre-driving voltage signal.

From the above, the LED display effect improving circuit provided by the embodiment of the application can complete three functions of shadow elimination (clamping) and pre-driving, so that the circuit structure is simplified, the area of an LED driving chip is saved, and the cost of the LED driving chip is further reduced.

It will be appreciated that the advantages of the second to third aspects may be found in the relevant description of the first aspect, and are not described in detail herein.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required for the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram I of a conventional common-cathode LED driver chip;

FIG. 2 is a schematic diagram of a prior art common-anode LED driver chip;

FIG. 3 is a schematic diagram II of a conventional common-cathode LED driver chip;

FIG. 4 is a schematic diagram III of a conventional common-cathode LED driver chip;

FIG. 5 is a schematic diagram of a conventional common-cathode LED driver chip;

fig. 6 is a schematic diagram of the structure of the clamp circuit, the pre-drive circuit, and the shadow elimination circuit in the conventional common-cathode LED driving chip;

FIG. 7 is a timing diagram of the clamp, pre-drive, and deghosting circuits;

FIG. 8 is a schematic diagram of an LED display effect enhancing circuit according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of an LED display effect enhancing circuit according to another embodiment of the present disclosure;

FIG. 10 is a schematic circuit diagram of an LED display effect enhancing circuit according to an embodiment of the present disclosure;

FIG. 11 is a schematic circuit diagram of an LED display effect enhancing circuit according to another embodiment of the present disclosure;

FIG. 12 is a timing diagram of an LED display effect enhancing circuit according to an embodiment of the present disclosure;

fig. 13 is a schematic structural diagram of an LED driving chip according to an embodiment of the present disclosure;

FIG. 14 is a schematic diagram of circuit connection of an LED driver chip according to an embodiment of the present disclosure;

fig. 15 is a schematic circuit connection diagram of an LED driving chip according to another embodiment of the present application.

In the figure: 10. LED display effect improving circuit; 20. a row driving circuit; 30. a column driving circuit; 40. an LED array; 100. a switch module; 200. a selection module; 201. a selection unit; 202. and a voltage follower unit.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

As used in this specification and the appended claims, the term "if" may be interpreted in context as "when …" or "upon" or "in response to determining" or "in response to detecting". Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".

In addition, in the description of the present application and the appended claims, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and are not to be construed as indicating or implying relative importance.

Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.

Currently, the main current LED driving modes include a common-negative type LED driving chip and a common-positive type LED driving chip, and the common-negative type LED driving chip is shown in fig. 1. Common cathode means that the cathodes of all LEDs in each row (Scan) are all tied together (source of common cathode) and the cathodes are controlled by row switches to control whether they are tied to ground or not; the anode of each LED is connected to the current channel of the common cathode LED driving chip, and the switching of the channel is controlled by the column switch of the LED Channel (CHN). Since the premise of LED turn-on is that the voltage difference between the anode and the cathode of the LED reaches VF value, it can be seen from fig. 1 that taking LED11 as an example, if LED11 is desired to turn on, the row switch in Scan1 needs to be turned on first, so that the cathode of LED is grounded; in addition, the current channel above led11 needs to be turned on, so that the parasitic capacitance at the anode node of led can be charged by the current above led until the anode voltage of led11 reaches VF value, at which point led11 is turned on. If all 3 leds of the first row are in the lighting stage, i.e. the row switch in Scan1 is turned on at this time, but led11 is required to be turned off at this time, only the column switch above led11 needs to be turned off, and leds 12 and 13 are still turned on. The above is the working principle of the common cathode type LED driving chip. The principle of the common positive type LED driving chip is the same as that of the common negative type LED driving chip, and all the LED anodes of each row are connected together at the moment, and whether the LED anodes are connected to a power supply or not is controlled through a row switch in Scan.

In order to improve the display effect of the LED, a shadow eliminating circuit, a pre-driving circuit and a clamping circuit are usually disposed in the LED driving chip, and the reason why the shadow eliminating circuit, the pre-driving circuit and the clamping circuit are disposed will be described below by taking the common-cathode LED driving chip as an example.

Because parasitic capacitance exists in the row lines and the column lines in the LED array, the parasitic capacitance is derived from the PCB wiring of the lamp panel. The capacitor has a basic characteristic, namely, the characteristic of storing charge, after the capacitor is charged for a certain time, corresponding charges are stored on two polar plates of the capacitor, if the capacitor is charged by disconnecting at the moment, the charges on the upper polar plate and the lower polar plate of the capacitor cannot disappear at the moment, namely, the voltage of the capacitor before the disconnection can be continuously maintained. These parasitic capacitances can cause the LED to ghost, i.e., the LED that is not lit will still emit light, during the LED panel display.

The mechanism of generating the ghost (column ghost) of the common-cathode LED driving chip is shown in fig. 3, assuming that when the row switch of the first row is turned on, LED11/LED12/LED13 is all turned on, at this time, since all channels have current output, and the positive electrode of LED11/LED12/LED13 is all charged and pulled high, i.e. the voltage at point a is high, after the first row display is finished, the row switch in Scan1 is turned off, and the second row display is started, at this time, the row switch in Scan2 is turned on, and the cathode of LED21/LED22/LED23 is pulled down to ground, assuming that only LED21/LED23 is turned on in this row display, and LED22 is not displayed, i.e. the column switch above LED22 is turned off. Theoretically, the positive electrode of led22 should be at a low level, led22 will not light up, but because of the parasitic capacitance of channel 2 (CHN 2), point a is already charged to a high voltage when the first row is turned on, and when the second row is turned on, since the voltage at point a will still maintain the previous high voltage, there is still a voltage difference between the positive electrode and the negative electrode of led22 at this time, and this voltage difference may cause led22 to turn on, i.e., led22 will also light up for a period of time, after a period of discharge, the voltage at point a decreases until the voltage between the voltage at point a and ground is less than the turn-on Voltage (VF) of led22, at which point led22 is turned off. As can be seen from the above analysis, led22 will still light up for a period of time at this extinction due to the parasitic capacitance of the channel, and this state of lighting up for this period of time is called ghosting, or column ghosting.

From the above analysis, it can be seen that in the LED display process, due to the influence of parasitic capacitances on the row lines and the column lines, ghosts appear in the display process, and the display effect is affected, so that a circuit is required to be designed to eliminate the ghosts, namely, a deghosting circuit.

As shown in fig. 4, the LED can be turned on only when the LED has an on voltage VF, i.e., the difference between the positive and negative voltages of the LED is greater than VF. Taking led13 as an example in fig. 4, the precondition that led13 can normally light is that the pressure difference between the AB nodes is greater than VF; when the row switch in Scan1 is turned on, the voltage at point B is 0, and when the CHN3 channel is turned on, led13 will not be turned on immediately, but it is necessary to charge point a to VF before led13 is turned on normally, and this charging time is not desirable, because this time directly affects the display time, such as when the gray level is low, the start time of led13 set by the system is very short (10 ns), if the charging time at point a is too long, led13 may not be turned on within 10ns, resulting in gray level loss. Therefore, a pre-driving circuit is needed, and the pre-driving circuit is used for pre-charging the point A to a certain voltage through the pre-charging circuit before the turn-on signal of the led13 arrives, and the voltage basically reaches the VF value required by the turn-on of the led13, so that the point A can be charged to the VF voltage in a short time after the turn-on signal of the led13 arrives, and the led13 can be quickly lightened. The pre-driving circuit is generally realized by an operational amplifier.

As shown in fig. 5, each LED has a parasitic capacitance, and when the row switch in Scan1 is turned on and the row switches in Scan2 and Scan3 are turned off, the cathodes of all the LEDs on the row lines of Scan2 and Scan3 are in a floating state, which is very susceptible to signal coupling interference. In specific operation, led11 is turned off on Scan1 line, and the anode of led11 floats. When led13 is turned on, the point a will be pulled up rapidly, and since the whole CHN3 column line is the same line, the point a will increase the row line voltage of Scan2/Scan3 through the self capacitance of led23/led33, and then increase the whole column line voltage of CHN1 through the self capacitance of led21/led31, i.e. the anode voltage of led11 will be pulled up due to the series of coupling effects, if the coupling effects are large enough, the anode voltage of led11 will be pulled up to above VF, and led11 that should be turned off at this time will be turned on by mistake. The reason for the coupling is that the row lines Scan2 and Scan3 are in a floating state when they are disconnected, and thus the interference is easily received. The solution is that when the row line is disconnected, the row line is clamped at a proper voltage value through a clamping circuit and does not change along with coupling interference of other signals, or the anode of led11 is clamped at a proper voltage value and does not change along with coupling interference of other signals. The clamping circuit is generally realized by an operational amplifier.

At present, the clamp circuit, the pre-drive circuit and the shadow eliminating circuit are all made inside the chip, as shown in fig. 6, taking the channel of the common-negative type LED driving chip as an example, in the figure, the shadow eliminating circuit, the clamp circuit and the pre-drive circuit are respectively formed by 3 different circuits, and as the three circuits are all applied to one node of the point a, different on-time needs to be set for the 3 circuits, namely, the 3 circuits cannot be simultaneously started.

Generally, for an LED driving chip, the timing sequence of shadow elimination, clamping and pre-driving on a channel is shown in fig. 7, and it can be seen from fig. 7 that in the whole display process, besides the display stage, there are three stages, namely, a shadow elimination stage, a clamping stage and a pre-driving stage, for better improving the display effect. All three of these stages consume additional display time. And because 3 different circuits are needed to complete the functions of 3 different stages, the consumption of hardware is larger, and a large chip area is occupied, so that the waste of the chip cost is caused.

In view of the above problems, taking the channel of the LED driving chip as an example, as shown in fig. 8 (the channel of the common-cathode LED driving chip) and fig. 9 (the channel of the common-anode LED driving chip), the embodiment of the present application provides an LED display effect enhancing circuit 10, which includes a switch module 100 and a selection module 200. One end of the switch module 100 is electrically connected between the column driving circuit of the LED driving chip and the column scanning line of the LED array. The selection module 200 is electrically connected to the other end of the switch module 100. The selection module 200 is used for outputting a clamp voltage signal or a pre-drive voltage signal to the switching module 100. When the column driving circuit of the LED driving chip is disconnected from the column scanning lines of the LED array, the selecting module 200 is configured to output a clamping voltage signal or a pre-driving voltage signal to the column scanning lines of the LED array through the switching module 100, so as to perform shadow elimination, clamping or pre-driving on the column scanning lines of the LED array.

Specifically, when the selection module 200 is used to output a clamp voltage signal to the column scan lines of the LED array through the switching module 100, a clamp (deghosting) mode is entered at this time to deghost and clamp the column scan lines of the LED array. The method and the device have the advantages that the shadow eliminating function is completed through the clamping voltage signal, and clamping is directly performed after the shadow eliminating function is completed.

When the selection module 200 is used to output the pre-driving voltage signal to the column scan lines of the LED array through the switching module 100, a pre-driving mode will be entered at this time to pre-drive the column scan lines of the LED array. The pre-driving function is completed through the pre-driving voltage signal.

From the above, it can be seen that the LED display effect enhancing circuit 10 provided in the embodiment of the present application can complete three functions of shadow elimination (clamping) and pre-driving, simplifying the circuit structure, saving the area of the LED driving chip, and further reducing the cost of the LED driving chip.

As shown in fig. 10 and 11, the selection module 200 includes a selection unit 201 and a voltage follower unit 202. The voltage follower unit 202 is electrically connected to the other end of the switch module 100 and the selection unit 201, respectively. The selection unit 201 is configured to output a clamp voltage signal or a pre-drive voltage signal to the voltage follower unit 202. The voltage follower unit 202 is used for providing a driving capability of a clamp voltage signal or a pre-drive voltage signal.

Specifically, the switch module 100 is configured to receive the first control signal pwm_enb, and when the column driving circuit of the LED driving chip is disconnected from the column scanning line of the LED array (i.e., the column switch CHNS in the column driving circuit is disconnected according to the control signal pwm_en), the switch module 100 is configured to be turned on according to the first control signal pwm_enb.

The selection unit 201 is configured to receive a second control signal clamp_en, a CLAMP voltage signal clamp_vref, and a PRE-drive voltage signal pre_drv_vref. When the second control signal clamp_en is the first level signal, a CLAMP (deghosting) mode will be entered at this time, and the selecting unit 201 is configured to output the CLAMP voltage signal clamp_vref to the column scan lines of the LED array through the voltage following unit 202 to deghost and CLAMP the column scan lines of the LED array. The CLAMP voltage signal clamp_VREF is used for completing the shadow eliminating function, and clamping is directly performed after the shadow eliminating function is completed. Wherein the first level signal is a high level signal.

When the second control signal clamp_en is the second level signal, a PRE-driving mode will be entered at this time, and the selecting unit 201 is configured to output the PRE-driving voltage signal pre_drv_vref to the column scan lines of the LED array through the voltage following unit 202 to PRE-drive the column scan lines of the LED array. The PRE-driving function is completed through a PRE-driving voltage signal PRE_DRV_VREF. Wherein the second level signal is a low level signal.

When the LED driving chip is a common-cathode LED driving chip, the pre-driving voltage signal is a charging voltage signal. When the LED driving chip is a common-anode type LED driving chip, the pre-driving voltage signal is a discharging voltage signal.

From the above, the LED display effect improving circuit 10 provided in the embodiment of the present application can perform three functions of shadow elimination (clamping) and pre-driving, simplifying the circuit structure, saving the area of the LED driving chip, and further reducing the cost of the LED driving chip; meanwhile, the display effect of the LED is improved.

In addition, in the aspect of time sequence control, the time sequence of the deghosting and the clamping is combined, as shown in fig. 12, namely, the purpose of deghosting is realized while multiplexing the clamping function, so that the effective display time can be improved.

When the column driving circuit of the LED driving chip acts on the column scanning line of the LED array (i.e., the column switch CHNS in the column driving circuit is turned on according to the control signal pwm_en), the switch module 100 is turned off according to the first control signal pwm_enb, and at this time, the LED display effect enhancing circuit 10 does not affect the column scanning line of the LED driving chip and does not affect the normal operation of the LED driving chip.

As shown in fig. 10 and 11, the selection unit 201 includes a selector MUX. The selector MUX is electrically connected to the voltage follower unit 202.

Specifically, the selection terminal of the selector MUX is configured to receive the second control signal clamp_en, and the first input terminal 1 of the selector MUX is configured to receive the CLAMP voltage signal clamp_vref. A second input terminal 0 of the selector MUX is for receiving the PRE-drive voltage signal pre_drv_vref, and an output terminal of the selector MUX is electrically connected to the voltage follower unit 202.

The selector MUX is mainly used for selecting corresponding voltage signals to output according to the second control signal clamp_en so as to complete the functions of shadow elimination (clamping) and pre-driving.

As shown in fig. 10 and 11, the voltage follower unit 202 includes an operational amplifier OPAMP. The noninverting input terminal of the operational amplifier OPAMP is electrically connected to the selection unit 201, and the inverting input terminal of the operational amplifier OPAMP is electrically connected to the output terminal of the operational amplifier OPAMP and the other end of the switching module 100, respectively. As can be seen from fig. 10 and 11, the noninverting input terminal of the operational amplifier OPAMP is electrically connected to the output terminal of the selector MUX in the selecting unit 201.

Wherein the operational amplifier OPAMP is mainly used for providing the driving capability of the CLAMP voltage signal clamp_vref or the pre_drv_vref of the PRE-drive voltage signal to complete the deghosting (clamping) and PRE-drive functions.

As shown in fig. 10 and 11, the switch module 100 includes a first switch S1. One end of the first switch S1 is electrically connected between the column driving circuit of the LED driving chip and the column scanning line of the LED array, the other end of the first switch S1 is electrically connected with the selection module 200, and the control end of the first switch S1 is used for receiving the first control signal pwm_enb. As can be seen from fig. 10 and 11, the other end of the first switch S1 is electrically connected to the inverting input terminal of the operational amplifier OPAMP and the output terminal of the operational amplifier OPAMP, respectively.

Specifically, the first switch S1 is mainly used for controlling the on and off of the LED display effect enhancing circuit 10. When the column driving circuit of the LED driving chip is disconnected from the column scanning line of the LED array, the first switch S1 is configured to be turned on according to the first control signal pwm_enb, so that the LED display effect enhancing circuit 10 acts on the column scanning line of the LED array, i.e. node a in fig. 10 and 11, and then the shadow elimination (clamping) and pre-driving functions are completed according to the timing control. When the column driving circuit of the LED driving chip acts on the column scanning line of the LED array, the first switch S1 is turned off according to the first control signal pwm_enb, so that the LED display effect enhancing circuit 10 cannot act on the column scanning line of the LED array, and the normal operation of the LED driving chip is not affected.

The first switch S1 is illustratively a metal-oxide semiconductor field effect transistor.

In summary, the LED display effect improving circuit 10 provided in the embodiment of the present application can complete three functions of shadow elimination (clamping) and pre-driving, simplifying the circuit structure, saving the area of the LED driving chip, and further reducing the cost of the LED driving chip. Meanwhile, the time sequence control is simplified, and the display time is optimized.

As shown in fig. 13, the embodiment of the present application further provides an LED driving chip, which includes a plurality of row driving circuits 20, a plurality of column driving circuits 30, and a plurality of LED display effect enhancing circuits 10 described above. The plurality of row driving circuits 20 are connected to the plurality of row scanning lines of the LED array 40 in a one-to-one correspondence manner, the plurality of column driving circuits 30 are connected to the plurality of column scanning lines of the LED array 40 in a one-to-one correspondence manner, and the plurality of LED display effect enhancing circuits 10 are electrically connected between the plurality of column driving circuits 30 and the plurality of column scanning lines of the LED array 40 in a corresponding manner.

Specifically, when the column driving circuit 30 is disconnected from the column scanning lines of the LED array 40, the LED display effect enhancing circuit 10 is used to perform the shadow (clamping) eliminating and pre-driving functions to enhance the display effect of the LEDs.

As shown in fig. 14, when the LED array 40 is a common-cathode LED array, the row driving circuit 20 includes a row switch ScanS. One end of the row switch ScanS is electrically connected to the row scanning line of the LED array 40, and the other end of the row switch ScanS is grounded. As shown in fig. 14, the column driving circuit 30 includes a constant current source I and a column switch CHNS. The input end of the constant current source I is used for being electrically connected with a power supply, the output end of the constant current source I is electrically connected with one end of the column switch CHNS, and the other end of the column switch CHNS is respectively electrically connected with the LED display effect improving circuit 10 and the column scanning lines of the LED array 40.

Specifically, as shown in fig. 14, LED1n to LED nn in the LED array 40 emits light when the row switch ScanSn is turned on and the column switches CHNS1 to CHNSn are turned on. When the column switch CHNSn is turned off, LED nn is turned off, and the LED display effect enhancing circuit 10 connected to the column switch CHNSn is used to perform the shadow (clamp) eliminating and pre-driving functions in order to enhance the display effect.

As shown in fig. 15, when the LED array 40 is a common-anode type LED array, the row driving circuit 20 includes a row switch ScanS. One end of the row switch ScanS is used for being electrically connected to a power supply, and the other end of the row switch ScanS is used for being electrically connected to a row scanning line of the LED array 40. As shown in fig. 15, the column driving circuit 30 includes a constant current source I and a column switch CHNS. One end of the column switch CHNS is electrically connected to the LED display effect enhancing circuit 10 and the column scanning line of the LED array 40, respectively, and the other end of the column switch CHNS is electrically connected to the input end of the constant current source I, the output end of which is grounded.

Specifically, as shown in fig. 15, when the row switch ScanSn is turned on, anodes of ledn1 to lednn in the LED array 40 are turned on. When the column switches CHNS1-CHNSn are turned on, ledn1 to lednn emit light. When the column switch CHNSn is turned off, LED nn is turned off, and the LED display effect enhancing circuit 10 connected to the column switch CHNSn is used to perform the shadow (clamp) eliminating and pre-driving functions in order to enhance the display effect.

The embodiment of the application also provides a display device which comprises the LED driving chip. The display device provided in this embodiment of the present application has the advantage of good display effect, and the specific working principle is described with reference to the working principle of the LED driving chip described above, which is not described herein again.

The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.

Claims (10)

1. An LED display effect boost circuit, comprising:

one end of the switch module is electrically connected between a column driving circuit of the LED driving chip and a column scanning line of the LED array;

the selection module is electrically connected with the other end of the switch module;

the selection module is used for outputting a clamping voltage signal or a pre-driving voltage signal to the switch module; when the column driving circuit of the LED driving chip is disconnected with the column scanning line of the LED array, the selecting module is used for outputting the clamping voltage signal or the pre-driving voltage signal to the column scanning line of the LED array through the switching module so as to perform shadow elimination, clamping or pre-driving on the column scanning line of the LED array.

2. The LED display effect boost circuit of claim 1, wherein the selection module comprises a selection unit and a voltage follower unit; the voltage following unit is respectively and electrically connected with the other end of the switch module and the selection unit; the selection unit is used for outputting the clamping voltage signal or the pre-driving voltage signal to the voltage following unit; the voltage follower unit is used for providing driving capability of the clamping voltage signal or the pre-driving voltage signal;

the switch module is used for receiving a first control signal, and is used for being conducted according to the first control signal when the column driving circuit of the LED driving chip is disconnected with the column scanning line of the LED array;

the selection unit is used for receiving a second control signal, the clamping voltage signal and the pre-driving voltage signal, and outputting the clamping voltage signal to the column scanning line of the LED array through the voltage following unit when the second control signal is a first level signal so as to perform shadow elimination and clamping on the column scanning line of the LED array; when the second control signal is a second level signal, the selection unit is configured to output the pre-driving voltage signal to the column scanning line of the LED array through the voltage follower unit, so as to pre-drive the column scanning line of the LED array.

3. The LED display effect promotion circuit of claim 2, wherein the selection unit includes a selector; the selector is electrically connected with the voltage follower unit.

4. The LED display effect boost circuit of claim 2, wherein the voltage follower unit comprises an operational amplifier; the non-inverting input end of the operational amplifier is electrically connected with the selection unit, and the inverting input end of the operational amplifier is electrically connected with the output end of the operational amplifier and the other end of the switch module respectively.

5. The LED display effect boost circuit of claim 1, wherein the switch module comprises a first switch; one end of the first switch is electrically connected between the column driving circuit of the LED driving chip and the column scanning line of the LED array, and the other end of the first switch is electrically connected with the selection module.

6. An LED driving chip, comprising:

the row driving circuits are used for being connected with a plurality of row scanning lines of the LED array in a one-to-one correspondence manner;

the plurality of column driving circuits are used for being correspondingly connected with a plurality of column scanning lines of the LED array one by one;

and a plurality of LED display effect enhancing circuits according to any one of claims 1 to 5, wherein a plurality of the LED display effect enhancing circuits are correspondingly and electrically connected between a plurality of the column driving circuits and a plurality of column scanning lines of the LED array.

7. The LED driver chip of claim 6, wherein when the LED array is a co-cathode LED array, the row driver circuit comprises a row switch; one end of the row switch is used for being electrically connected with a row scanning line of the LED array, and the other end of the row switch is grounded.

8. The LED driver chip of claim 7, wherein the column driver circuit comprises a constant current source and a column switch; the input end of the constant current source is used for being electrically connected with a power supply, the output end of the constant current source is electrically connected with one end of the column switch, and the other end of the column switch is electrically connected with the LED display effect improving circuit and the column scanning line of the LED array respectively.

9. The LED driver chip of claim 6, wherein when the LED array is a co-cationic LED array, the row driver circuit comprises a row switch; one end of the row switch is used for being electrically connected with a power supply, and the other end of the row switch is used for being electrically connected with a row scanning line of the LED array;

the column driving circuit comprises a constant current source and a column switch; one end of the column switch is electrically connected with the LED display effect lifting circuit and the column scanning line of the LED array respectively, the other end of the column switch is electrically connected with the input end of the constant current source, and the output end of the constant current source is grounded.

10. A display device comprising the LED driving chip according to any one of claims 6 to 9.

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