CN102522063A - LED (light-emitted diode) display system capable of eliminating dynamic LED display ghost - Google Patents

Abstract

The invention relates to an LED (light-emitted diode) display system capable of eliminating dynamic LED display ghost includes a power supply module, an LED array, M switch tubes, a decoding circuit, multiple constant-current driving circuits and a main controller, wherein each constant-current driving circuit is provided with a discharge module, the main controller sends discharge control signals to communication and control modules of all constant-current driving circuits through a control bus when LED lines are being switched in the LED array during the dynamic displaying time, and the discharge module of each constant-current driving circuit discharges a spurious charge at the second end of each cut-off PMOS switch tube from an output port of the discharge module to the system. Superior ghost removing effect can be realized only through a minor hardware modification in the traditional LED display system and the system of the invention has strong practicability.

Description

A kind of LED of elimination dynamically shows the LED display system of ghost

Technical field

The present invention relates to LED demonstration field and relate in particular to the LED display system that a kind of LED of elimination dynamically shows ghost.

Background technology

The display mode of LED display system can be divided into static the demonstration and dynamically demonstration; Static each the constant current source passage that is meant constant-current drive circuit that shows drives one tunnel specific LED all the time, dynamically shows to be meant that each constant current source passage of constant-current drive circuit can drive different LED respectively in different time.

Traditional LED display system, as shown in Figure 1, mainly comprise power module 1, ledarray 2, constant-current drive circuit 3,switching tube 6, decoding scheme 7 and master controller 8: power module 1 output DC source VCC, giveled array 2 and constant-current drive circuit 3 power supplies;Led array 2 is made up of the capable N row of M LED, and each LED comprises anode and negative electrode; Constant-current drive circuit 3 comprises the constantcurrent source 5 of communication and control module 4 and several passages; Wherein each passage constant current source is used for a steady current to LED being provided; Opening and shutting off of constantcurrent source 5 receives communication and control module 4 controls, and the opening time dutycycle of the size of steady current and constant current source determines the brightness of LED jointly; Switchingtube 6 is that the LED dynamic display system is needed with decoding scheme 7, and the switching tube on the LED display adopts the PMOS pipe usually, comprises source electrode, drain and gate.The source electrode first termination power VCC of each switching tube, drain electrode connects the anode of the LED of delegation, and the negative electrode of the same LED that lists is connected to same constant current source.Decoding scheme comprises coding input end CODE and several decoding output terminals DECODE1～DECODEm, and each decoding output terminal is connected to the grid of aswitching tube 6, in order to control each row LED with conducting and shutoff between the power supply.It is effective that decoding scheme has only an output signal at one time; This has just determined at the same time, to have only a switching tube is conducting; Having only with the continuous LED of delegation of the switching tube of this conducting to be communicated with power supply, is effectively, and all the other each row LED are invalid.Master controller 8 is responsible for coded signal CODE to decoding scheme 7 being provided; In order to select currently to want the LED of delegation that shows to make it effective; Master controller 8 also follows communicating by letter of constant-current drive circuit 3 through data line with control bus 9 and control module 4 communicates; Be used for controlling the opening time dutycycle of each constant current source, thus the brightness of each LED among the control current effective LED of delegation.Pass through the data line cascade between each constant-current drive circuit 3, and under the effect of control bus 9, receive master controller 8 controls, carry out the control of data transmission and duty.

Because the general area of switching tube is bigger, bigger stray capacitance is arranged, when certain switching tube conducting; Its drain voltage is near supply voltage; Be expert at when switching, need this switching tube is turn-offed so that the LED of delegation that this switching tube connected is invalid, and next switching tube is opened to show next line LED; Because the existence of the stray capacitance of pipe; The drain voltage of the switching tube that just has been turned off still remains near supply voltage, and needing a discharge path could fall the charge discharging resisting on the stray capacitance, thereby drain voltage is fallen.If not waiting its drain voltage falls; Just want data presented that constant current source is opened by next line; Then because the negative electrode of the LED of different rows is all received same group of constant current source, the drain electrode electric charge of the switching tube that just has been turned off is through in the constant current source of opening of releasing to its LED of delegation that should be disabled that links to each other, if the constant current source negligible amounts of opening this moment; The charge concentration of the switching tube drain electrode that then is turned off is released through the LED of minority; Can make these be disabled not should bright LED occur that eyes can obviously feel little bright originally, be referred to as ghost here, this ghost can influence picture display effect.The constant current source that open this moment is few more, and ghost is just obvious more, and is also just big more to the influence of picture display effect.

If the refresh rate of LED display is high more in addition, the switching rate of then going is also high more, then receives the influence of switching tube spurious charge also can be big more in the unit interval, and ghost also can be obvious more.And along with the continuous lifting of LED display technique, to refresh rate require increasingly highly, how the ghost that dynamically shows of easily and effectively elimination has been very a reality and the problem that can not be ignored.

The principle that shows ghost according to above generation; Can know that the key of eliminating ghost is to be expert at when switching the spurious charge of switching tube to be released; The method or the effect of present existing elimination ghost are bad; Need to add extra components and parts and control line, bigger to the change of hardware, use little convenience.

Summary of the invention

The present invention is intended to solve the deficiency of prior art; Proposed a kind ofly can eliminate the LED display system that LED dynamically shows ghost; This system carries out the less hardware change on traditional LED display system can realize the shadow effect that disappears preferably, has very strong practicality.

Eliminate the LED display system that LED dynamically shows ghost, comprising:

Power module, said power module output DC source are given led array and constant-current drive circuit power supply;

Led array, said led array comprise the capable N row of M LED, and each LED comprises anode and negative electrode;

M switching tube, first end of a said M switching tube connects power module, and second end of each switching tube connects the anode of the LED of delegation in the led array respectively, through the conducting and the switching of turn-offing each row LED in the realization LED array of display of switching tube;

Decoding scheme; The input end of said decoding scheme connects master controller and accepts the capable switching of the LED coded data of master controller; The output terminal of said decoding scheme connects each control end of switching tube; And, has only a switching tube conducting at one time according to the conducting and the shutoff of M switching tube of the capable switching of said LED coded data control;

Some constant-current drive circuits and master controller;

It is characterized in that; Said each constant-current drive circuit comprises communication and control module, constant current source, discharge module: said communication is connected master controller with control module, and receives conducting and the cut-off signals and the discharge control signal of the constant current source that said master controller sends; Said constant current source connects communication and is connected the row of one in led array LED negative electrode respectively, brightness and the gray scale of the size of current of constant current source output and ON time dutycycle decision LED with control module and according to said conducting and the conducting of cut-off signals control LED and the output terminal of shutoff constant current source that master controller sends; Said discharge module comprises control end, output and ground; The control end of said discharge module connects communication and control module and receives the discharge control signal that said master controller sends; The output terminal of said discharge module connects second end of said switching tube; The earth terminal of said discharge module connects ground wire; When in dynamically showing, carrying out the capable switching of LED in the led array, the discharge module of each constant-current drive circuit with the spurious charge of each switching tube that is turned off second end from the output port of the discharge module ground of releasing.

Said switching tube is the PMOS pipe, and first end of said switching tube is a source electrode, and second end of said switch is drain electrode, and said control end of switching tube is a grid.

The invention has the beneficial effects as follows: through transforming constant-current drive circuit and the control program of revising master controller, need not add extra components and parts on the hardware, also need not add extra control line, can effectively eliminate ghost.Compare the existing shadow scheme that disappears, have that hardware is changed less, the shadow good effectiveness that disappears, have very strong practicality.

Description of drawings

Come the present invention is done further explain below in conjunction with accompanying drawing, wherein:

Fig. 1 is traditional LED display system.

Fig. 2 is the LED display system that a kind of LED of elimination that the present invention proposes dynamically shows ghost.

Fig. 3 is an embodiment of discharge module of the present invention.

Fig. 4 is another embodiment of discharge module of the present invention.

Fig. 5 is another embodiment of discharge module of the present invention.

Embodiment

The present invention propose a kind of can be simple and effective elimination LED dynamically show the LED display system of ghost.This system need not change traditional system architecture; At the inner discharge module that adds of constant-current drive circuit; Only need during use second end of each switching tube is connected to different constant-current drive circuits; And the control program of modification master controller, when carrying out the capable switching of LED, release the second end spurious charge that is turned off switching tube through the inner discharge module of constant-current drive circuit, thereby eliminate ghost.

Eliminate the LED display system that LED dynamically shows ghost, comprising:

Power module 1, said power module 1 output DC source are given ledarray 2 and constant-current drive circuit 3 power supplies;

Ledarray 2, said ledarray 2 comprise the capable N row of M LED, and each LED comprises anode and negative electrode, through the gray scale of each LED and the displaying contents and the display effect of brightness realization led array;

M switching tube 6, first end of a saidM switching tube 6 connects power module 1, and second end of each switching tube connects the anode of the LED of delegation in the led array respectively, through the conducting and the switching of turn-offing each row LED in the realization LED array of display ofswitching tube 6;

Decoding scheme 7; The input end of said decoding scheme 7 connects master controller 8 and accepts the capable switching of the LED coded data of master controller 8; The output terminal of said decoding scheme 7 is according to the conducting and the shutoff of M switching tube of the capable switching of said LED coded data control, and having only a switching tube at one time is conducting;

Some constant-current drive circuits 3 and master controller 8;

Wherein, Constant-current drive circuit 3; Said constant-current drive circuit 3 comprises communication and control module 4, constantcurrent source 5, discharge module 10: said communication is connected master controller 8 with control module 4, and receives conducting and the cut-off signals and the discharge control signal of the constantcurrent source 5 that said master controller 8 sends; Said constantcurrent source 5 connects communication and control module 4 and the said conducting of sending according to master controller 8 and cut-off signals are controlled LED conducting and shutoff; The output terminal of constantcurrent source 5 connects the row of one in led array LED negative electrode respectively, brightness and the gray scale of the size of current of constantcurrent source 5 outputs and ON time dutycycle decision LED; Saiddischarge module 10 comprises control end, output and ground; The control end of saiddischarge module 10 connects communication and control module 4 and receives the discharge control signal that said main control 8 devices send; The output terminal of saiddischarge module 10 connects second end of saidswitching tube 6; The earth terminal of saiddischarge module 10 connects ground wire; When in dynamically showing, carrying out the capable switching of LED in the led array, the discharge module of each constant-current drive circuit with the spurious charge of each PMOS switching tube second end that is turned off from the output port of the discharge module ground of releasing.

Simultaneously said master controller 8 is connected the communication and the control module 4 of each constant-current drive circuit 3 with control bus 9 through data line; To need gray-scale displayed data and control signal to send to each constant-current drive circuit 3 through data line and control line, the displaying contents and the display effect of control ledarray 2; Said master controller 8 provides the coded data of the capable switching of LED in the led array for decoding scheme 7.

Fig. 3 is the embodiment of a discharge module, utilizes a NMOS pipe as switching tube, realizes discharge control, and the grid of NMOS is as control end, and drain electrode is as output terminal, and source electrode is an earth terminal.When the control signal that receives when control end was high level, NMOS managed conducting, produces the electric current from the output terminal to the ground wire, and the size of electric current is decided by the breadth length ratio of NMOS pipe; When the control signal that receives when control end was low level, the NMOS pipe ended, and the electric current from the output terminal to the ground wire is 0.

Fig. 4 is another embodiment of discharge module; Utilize a NMOS pipe as switching tube, the drain electrode of NMOS pipe connects an end of resistance, and the other end of resistance is as the output terminal of discharge module; The grid of NMOS pipe is as control end, and the source electrode of NMOS pipe is as earth terminal.When the control signal that receives when control end was high level, NMOS managed conducting, produce one from output terminal through the electric current of resistance to ground wire, the size of electric current is limited by resistance; When the control signal that receives when control end was low level, the NMOS pipe ended, and the electric current from the output terminal to the ground wire is 0.

Fig. 5 is another embodiment of discharge module, utilizes a current source to realize discharge.During the control signal of the unlatching discharge module that receives when control end, current source is opened, and produces the electric current from the output terminal to the ground wire, and the size of electric current is exactly the current value of current source; When control end received the control signal of turn-offing discharge module, current source turn-offed, and the electric current from the output terminal to the ground wire is 0.

The above is merely preferred implementation of the present invention, but protection domain of the present invention is not limited thereto.Any those skilled in the art all can carry out suitable change or variation to it in technical scope disclosed by the invention, as to the modification of discharge module etc., and this change or change all should be encompassed within protection scope of the present invention.

Claims (1)

1. eliminate the LED display system that LED dynamically shows ghost, comprising:

Power module, said power module output DC source are given led array and constant-current drive circuit power supply;

Led array, said led array comprise the capable N row of M LED, and each LED comprises anode and negative electrode;

M switching tube, first end of a said M switching tube connects power module, and second end of each switching tube connects the anode of the LED of delegation in the led array respectively, through the conducting and the switching of turn-offing each row LED in the realization LED array of display of switching tube;

Decoding scheme; The input end of said decoding scheme connects master controller and accepts the capable switching of the LED coded data of master controller; The output terminal of said decoding scheme connects each control end of switching tube; And, has only a switching tube conducting at one time according to the conducting and the shutoff of M switching tube of the capable switching of said LED coded data control;

Some constant-current drive circuits and master controller;

It is characterized in that; Said each constant-current drive circuit comprises communication and control module, constant current source, discharge module: said communication is connected master controller with control module, and receives conducting and the cut-off signals and the discharge control signal of the constant current source that said master controller sends; Said constant current source connects communication and is connected the row of one in led array LED negative electrode respectively, brightness and the gray scale of the size of current of constant current source output and ON time dutycycle decision LED with control module and according to said conducting and the conducting of cut-off signals control LED and the output terminal of shutoff constant current source that master controller sends; Said discharge module comprises control end, output and ground; The control end of said discharge module connects communication and control module and receives the discharge control signal that said master controller sends; The output terminal of said discharge module connects second end of said switching tube; The earth terminal of said discharge module connects ground wire; When in dynamically showing, carrying out the capable switching of LED in the led array, the discharge module of each constant-current drive circuit with the spurious charge of each switching tube that is turned off second end from the output port of the discharge module ground of releasing.

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