CN203596163U - Shadow elimination circuit without non-controllable illumination used for LED display screen - Google Patents
Shadow elimination circuit without non-controllable illumination used for LED display screen Download PDFInfo
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- CN203596163U CN203596163U CN201320628493.4U CN201320628493U CN203596163U CN 203596163 U CN203596163 U CN 203596163U CN 201320628493 U CN201320628493 U CN 201320628493U CN 203596163 U CN203596163 U CN 203596163U
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Abstract
The utility model discloses a shadow elimination circuit without non-controllable illumination used for an LED display screen. The shadow elimination circuit is disposed in a horizontal driving circuit of a 1/4 scanning row sub-controlled LED display screen. The shadow elimination circuit is characterized in that a triode switch circuit is disposed among a corresponding decoding chip row control line output end, a row line output end of a field effect transistor, and a common ground; when the row control line output end is converted from the low level into the high level, the row line output end can be used to drag the row power supply down quickly; the connection with the common ground can be disconnected along with the charging of an isolation capacitor; the time of the overlap between the former row and the latter row of one frame image is approximately 30s by selecting the device parameters, and then the overlapping time approximates to the fall time of the row power supply. The shadow elimination circuit is advantageous in that the circuit is simple, and the costs are low; the non-controllable illumination of the LED of other rows under the driving of the row power supply can be effectively eliminated, and even when the non-controllable illumination of the LED caused by the electric leakage of the LED occurs, the trailing phenomenon of the LED display screen can be greatly improved, and the human eyes cannot identify the glimmer of the former row.
Description
Technical field
The utility model relates to LED display, particularly relates to a kind of control nothing but for LED display and lights the shadow circuit that disappears.
Background technology
Light emitting diode (Light Emitting Diode, initialism is LED) display screen adopts scan mode mostly, the general control mode of scan screen is ranks sub-control mode, it is usually said scan mode, many scan patterns of LED display generally include 1/2 scan pattern, 1/4 scan pattern, 1/8 scan pattern and 1/16 scan pattern, it is similar that LED reverse leakage under these scan patterns is improved circuit structure, as an example of 1/4 scan pattern example, existing LED reverse leakage improved to circuit below and be explained.Row driving power pipe in the driving circuit of LED display, substantially be all to adopt two P channel metal-oxide-semiconductor field (Metal-Oxide-S emiconductor Field-Effect-Transistor, initialism is MOSFET) 4953, its inside comprises separate two P-channel field-effect transistor (PEFT) pipe MOSFET1, MOSFET2, there is ultralow conducting resistance, drive two display lines, 1/4 scanning ranks sub-control driving circuit as shown in Figure 1.In one two field picture of the LED display of 1/4 scan pattern, every row LED only showed for 1/4 time, row selects signal after high speed Si-gate complementary MOS (Complementary MOS, initialism is CMOS) coding chip 74HC138 decoding, to control respectively two P-channel field-effect transistor (PEFT) pipe MOSFET1, the grid G 1 of MOSFET2, the G2 of MOSFET4953.Due to the stray capacitance of field effect transistor MOSFET1, MOSFET2 and the impact of distributed capacitance, the row power supply rise time is very short, negligible, but, row power supply Tf>100 fall time μ s, cause in a two field picture, there are Tn approximately 100 μ s overlapping time that are approximately row power supply Tf fall time in previous row and rear a line, in the time that row power tube is closed, while showing next line, previous row still can be lighted in Tn in overlapping time, in people's vision, there will be conditions of streaking, claim again the effect of " previous row is in glimmer ".The degree of described " previous row is in glimmer " to overlapping time Tn be directly proportional to the overlapping ratio Tn/Tm of the displaying time Tm of every row, if frame frequency is 500Hz, the displaying time of every row is Tm=1000/ (500 × 4)=0.5ms, overlapping ratio is Tn/Tm=0.1/ (1000/ (4 × 500))=20%, and the effect of " previous row is in glimmer " that so large overlapping ratio is corresponding can have a strong impact on display effect.The method of existing solution conditions of streaking is being on the scene effect pipe MOSFET1, the each earthy resistance that adds of line output terminal of MOSFET2 arrives publicly, charge discharging resisting on each line is arrived publicly, and by selecting the resistance of earthy resistance to shorten Tf fall time of row power supply, the resistance of for example selecting earthy resistance is 27K Ω, the about 30ns of the Tf fall time left and right of row power supply, corresponding overlapping ratio Tn/Tm=30 × 10-6/ (1000)/(4 × 500))=0.006%, solution conditions of streaking that can be to a certain degree, but, while there is reverse leakage in certain the row LED listing if a certain, in the time that row power tube turn-offs, and the binary weighting address input end A0 of coding chip 74HC138, the row of A1 input selects signal changing always.
Row selects the low effective row control line output terminal Y0 output row control line of signal through the mutual exclusion of coding chip 74HC138, to pair control pin 2 of the field effect transistor MOSFET1 of P channel mosfets 4953 inside, it is the grid G 1 of field effect transistor MOSFET1, control 7,8 pin that field effect transistor MOSFET1 is connected, i.e. the line of the line output terminal H1 of field effect transistor MOSFET1 output;
Row selects the low effective row control line output terminal Y1 output row control line of signal through the mutual exclusion of coding chip 74HC138, comprise to two P channel mosfets 4953 inside two independently, the control pin 4 of P-channel field-effect transistor (PEFT) pipe MOSFET1, it is the grid G 2 of field effect transistor MOSFET1, control 5,6 pin that field effect transistor MOSFET1 is connected, i.e. the line of the line output terminal H2 of field effect transistor MOSFET1 output;
Row selects the low effective row control line output terminal Y2 output row control line of signal through the mutual exclusion of coding chip 74HC138, comprise to two P channel mosfets 4953 inside two independently, the control pin 2 of P-channel field-effect transistor (PEFT) pipe MOSFET2, it is the grid G 1 of field effect transistor MOSFET2, control 7,8 pin that field effect transistor MOSFET2 is connected, i.e. the line of the line output terminal H3 of field effect transistor MOSFET2 output;
Row selects the low effective row control line output terminal Y3 output row control line of signal through the mutual exclusion of coding chip 74HC138, comprise to two P channel mosfets 4953 inside two independently, the control pin 4 of P-channel field-effect transistor (PEFT) pipe MOSFET2, it is the grid G 2 of field effect transistor MOSFET2, control 5,6 pin that field effect transistor MOSFET2 is connected, i.e. the line of the line output terminal H4 of field effect transistor MOSFET2 output.
1,3 pin of field effect transistor MOSFET1 connect VCC, only has the control pin 2 as field effect transistor MOSFET1, be that the grid G 1 of field effect transistor MOSFET1 is during for low level, corresponding row power turn-on, 7,8 pin that are connected, be the line output terminal H1 output line of field effect transistor MOSFET1, otherwise be output as high-impedance state, drain D 1 is opened a way; Only have the control pin 4 as field effect transistor MOSFET1, when the grid G 2 of field effect transistor MOSFET1 is low level, corresponding row power turn-on, 5,6 pin that are connected, be the line output terminal H2 output line of field effect transistor MOSFET1, otherwise be output as high-impedance state, drain D 2 is opened a way;
1,3 pin of field effect transistor MOSFET2 connect VCC, only has the control pin 2 as field effect transistor MOSFET2, be that the grid G 1 of field effect transistor MOSFET2 is during for low level, corresponding row power turn-on, 7,8 pin that are connected, be the line output terminal H3 output line of field effect transistor MOSFET1, otherwise be output as high-impedance state, drain D 1 is opened a way; Only have the control pin 4 as field effect transistor MOSFET2, when the grid G 2 of field effect transistor MOSFET2 is low level, corresponding row power turn-on, 5,6 pin that are connected, be the line output terminal H4 output line of field effect transistor MOSFET2, otherwise be output as high-impedance state, drain D 2 is opened a way.
In the time that row power tube turn-offs, line H1 in the LED of 1/4 scanning dot matrix display screen, H2, H3 and H4 are successively in output procedure, LED on other row of same column by the LED by same column reverse leakage and with reverse leakage LED the earthy resistance that is connected on corresponding line to forming publicly loop, being on the scene effect pipe MOSFET1, under the output of MOSFET2 line, under the driving of power supply, the LED on other row of same column lights uncontrolled at once, be that non-control is lighted, if counting, the LED that non-control is lighted is greater than 1/10000, can affect the display effect of LED display.
Summary of the invention
Technical problem to be solved in the utility model is the defect that makes up above-mentioned prior art, provides a kind of control nothing but for LED display to light the shadow circuit that disappears.
Technical matters of the present utility model is solved by the following technical programs.
The shadow circuit that disappears is lighted in this control nothing but for LED display, be arranged in the horizontal drive circuit of LED display of 1/4 scanning ranks sub-control, described horizontal drive circuit comprises that the row that is provided with binary weighting address selects signal input part A0, the low effective row control line output terminal Y0 of A1 and mutual exclusion, Y1, Y2, the coding chip 74HC138 of Y3, and two P channel metal-oxide-semiconductor field (the Metal-Oxide-Semiconductor Field-Effect-Transistor that are connected with described coding chip 74HC138, initialism is MOSFET) 4953, its inside comprises two independently, P-channel field-effect transistor (PEFT) pipe MOSFET1, MOSFET2, the control pin 2 of described output terminal Y0 and field effect transistor MOSFET1, the grid G 1 that is field effect transistor MOSFET1 connects, the control pin 4 of described output terminal Y1 and field effect transistor MOSFET1, the grid G 2 that is field effect transistor MOSFET1 connects, the control pin 2 of described output terminal Y2 and field effect transistor MOSFET2, the grid G 1 that is field effect transistor MOSFET2 connects, the control pin 4 of described output terminal Y3 and field effect transistor MOSFET2, the grid G 2 that is field effect transistor MOSFET2 connects, field effect transistor MOSFET1 be connected 7, 8 pin are line output terminal H1, field effect transistor MOSFET1 be connected 5, 6 pin are line output terminal H2, field effect transistor MOSFET2 be connected 7, 8 pin are line output terminal H3, field effect transistor MOSFET2 be connected 5, 6 pin are line output terminal H4.
The feature that the shadow circuit that disappears is lighted in this control nothing but for LED display is:
At described row control line output terminal Y0, described line output terminal H1 and publicly between be provided with the first transistor switching circuit, described the first transistor switching circuit comprises the first triode, be connected to the first coupling branch road being formed by the first isolation resistance and the first isolation capacitance between described row control line output terminal Y0 and described the first transistor base, be connected to the first electrode resistance between described the first transistor base and emitter, and be connected to the first collector resistance between described the first transistor collector and described line output terminal H1, described row control line output terminal Y0 and be the input end of described the first transistor switching circuit publicly, described line output terminal H1 and be the output terminal of described the first transistor switching circuit publicly,
When the row control line output terminal Y0 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the first isolation capacitance both end voltage is " 0 ", select the ratio of the first isolation resistance and the first electrode resistance, make the first triode saturation conduction, line output terminal H1 by the first collector resistance the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the first isolation capacitance, its both end voltage raises gradually, electric current by the first isolation capacitance reduces gradually, until make the first triode cut-off, the first collector resistance i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y0 of coding chip 74HC138 is when exporting high level and become low level, the first isolation capacitance electric discharge, to return to original state, the ON time of the first triode is exactly row power supply Tf fall time, select the resistance of the first isolation resistance and the first electrode resistance and the capacitance of the first isolation capacitance, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ",
At described row control line output terminal Y1, described line output terminal H2 and publicly between be provided with the second transistor switching circuit, described the second transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, described the second transistor switching circuit comprises the second triode, be connected to the second coupling branch road being formed by the second isolation resistance and the second isolation capacitance between described row control line output terminal Y1 and described the second transistor base, be connected to the second electrode resistance between described the second transistor base and emitter, and be connected to the second collector resistance between described the second transistor collector and described line output terminal H2, described row control line output terminal Y1 and be the input end of described the second transistor switching circuit publicly, described line output terminal H2 and be the output terminal of described the second transistor switching circuit publicly,
When the row control line output terminal Y1 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the second isolation capacitance both end voltage is " 0 ", select the ratio of the second isolation resistance and the second electrode resistance, make the second triode saturation conduction, line output terminal H2 by the second collector resistance the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the second isolation capacitance, its both end voltage raises gradually, electric current by the second isolation capacitance reduces gradually, until make the second triode cut-off, the second collector resistance i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y1 of coding chip 74HC138 is when exporting high level and become low level, the second isolation capacitance electric discharge, to return to original state, the ON time of the second triode is exactly row power supply Tf fall time, select the resistance of the second isolation resistance and the second electrode resistance and the capacitance of the second isolation capacitance, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ",
At described row control line output terminal Y2, described line output terminal H3 and publicly between be provided with the 3rd transistor switching circuit, described the 3rd transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, described the 3rd transistor switching circuit comprises the 3rd triode, be connected to the 3rd coupling branch road being formed by the 3rd isolation resistance and the 3rd isolation capacitance between described row control line output terminal Y2 and described the 3rd transistor base, be connected to the 3rd electrode resistance between described the 3rd transistor base and emitter, and be connected to the 3rd collector resistance between described the 3rd transistor collector and described line output terminal H2, described row control line output terminal Y2 and be the input end of described the 3rd transistor switching circuit publicly, described line output terminal H3 and be the output terminal of described the 3rd transistor switching circuit publicly,
When the row control line output terminal Y2 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the 3rd isolation capacitance both end voltage is " 0 ", select the ratio of the 3rd isolation resistance and the 3rd electrode resistance, make the 3rd triode saturation conduction, line output terminal H2 by the 3rd collector resistance the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the 3rd isolation capacitance, its both end voltage raises gradually, electric current by the 3rd isolation capacitance reduces gradually, until make the 3rd triode cut-off, the 3rd collector resistance i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y2 of coding chip 74HC138 is when exporting high level and become low level, the 3rd isolation capacitance electric discharge, to return to original state, the ON time of the 3rd triode is exactly row power supply Tf fall time, select the resistance of the 3rd isolation resistance and the 3rd electrode resistance and the capacitance of the 3rd isolation capacitance, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ",
At described row control line output terminal Y3, described line output terminal H4 and publicly between be provided with the 4th transistor switching circuit, described the 4th transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, described the 4th transistor switching circuit comprises the 4th triode, be connected to the 4th coupling branch road being formed by the 4th isolation resistance and the 4th isolation capacitance between described row control line output terminal Y3 and described the 4th transistor base, be connected to the 4th electrode resistance between described the 4th transistor base and emitter, and be connected to the 4th collector resistance between described the 4th transistor collector and described line output terminal H4, described row control line output terminal Y3 and be the input end of described the 4th transistor switching circuit publicly, described line output terminal H4 and be the output terminal of described the 4th transistor switching circuit publicly,
When the row control line output terminal Y3 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the 4th isolation capacitance both end voltage is " 0 ", select the ratio of the 4th isolation resistance and the 4th electrode resistance, make the 4th triode saturation conduction, line output terminal H2 by the 4th collector resistance the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the 4th isolation capacitance, its both end voltage raises gradually, electric current by the 4th isolation capacitance reduces gradually, until make the 4th triode cut-off, the 4th collector resistance i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y3 of coding chip 74HC138 is when exporting high level and become low level, the 4th isolation capacitance electric discharge, to return to original state, the ON time of the 4th triode is exactly row power supply Tf fall time, select the resistance of the 4th isolation resistance and the 4th electrode resistance and the capacitance of the 4th isolation capacitance, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ".
The function of described the first transistor switching circuit, the second transistor switching circuit, the 3rd transistor switching circuit and the 4th transistor switching circuit is as follows:
In the time scanning next line, the first transistor switching circuit, the second transistor switching circuit, the 3rd transistor switching circuit and the 4th transistor switching circuit are in saturation conduction state, when after row power supply Tf fall time of previous row, described the first transistor switching circuit, the second transistor switching circuit, the 3rd transistor switching circuit and the 4th transistor switching circuit are in cut-off state, make described the first collector resistance, the second collector resistance, the 3rd collector resistance and the 4th collector resistance, be that earthy resistance in the circuit of original solution conditions of streaking disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, effectively eliminate with listing the LED non-control under the driving of power supply of being expert at and light.
Technical matters of the present utility model is solved by following further technical scheme.
Described the first triode, the second triode, the 3rd triode and the 4th triode are the NPN type switch triodes that cutoff frequency is at least 100MHz.
Described the first triode, the second triode, the 3rd triode and the 4th triode are that model is the low-power consumption NPN type switch triode of BC817.
Described the first isolation resistance, the second isolation resistance, the 3rd isolation resistance and the 4th isolation resistance, it is chip fixed resistance, described the first isolation resistance, the second isolation resistance, the 3rd isolation resistance and the 4th isolation resistance, excessive for Limited Current, avoid respectively burning the first triode, the second triode, the 3rd triode and the 4th triode.
Preferably, described the first isolation resistance, the second isolation resistance, the 3rd isolation resistance and the 4th isolation resistance, be the accurate chip fixed resistance that pin is processed into F type.
Described the first isolation capacitance, the second isolation capacitance, the 3rd isolation capacitance and the 4th isolation capacitance, it is ceramics isolation capacitance, described the first isolation capacitance, the second isolation capacitance, the time that discharges and recharges of the 3rd isolation capacitance and the 4th isolation capacitance is respectively by described the first isolation capacitance and described the first isolation resistance, the second isolation capacitance and described the second isolation resistance, the 3rd isolation capacitance and described the 3rd isolation resistance and the 4th isolation capacitance and described the 4th isolation resistance determine jointly, for precisely controlling respectively the first triode, the second triode, the ON time of the 3rd triode and the 4th triode.
Described the first electrode resistance, the second electrode resistance, the 3rd electrode resistance and the 4th electrode resistance, it is chip fixed resistance, described the first electrode resistance, the second electrode resistance, the 3rd electrode resistance and the 4th electrode resistance, the first triode is respectively used to release, the second triode, the base charge of the 3rd triode and the 4th triode, make respectively the first isolation capacitance, the second isolation capacitance, the 3rd isolation capacitance and the 4th isolation capacitance return to original state and guarantee respectively the first triode, the second triode, the 3rd triode and the 4th triode are in cut-off state.
Described the first collector resistance, the second collector resistance, the 3rd collector resistance and the 4th collector resistance, be chip fixed resistance, it is to guarantee that respectively the first triode, the second triode, the 3rd triode and the 4th triode are in saturation conduction state that its resistance is selected.
The utility model beneficial effect is compared with prior art:
The utility model circuit is simple, and cost is lower.At the corresponding capable control line output terminal of coding chip, the line output terminal of field effect transistor and publicly between be provided with transistor switching circuit, when row control line output terminal is when output low level becomes high level, line output terminal drags down row power supply rapidly, along with the charging of isolation capacitance, disconnect and being connected publicly, and selector parameter makes the interior previous row of a two field picture and rear a line have the overlapping time that is about 30ns, approximate with the fall time of row power supply, can effectively eliminate its row LED of same column non-control under the driving of power supply of being expert at lights, even because LED electric leakage causes the non-control of some LED to be lighted, also can significantly improve LED display conditions of streaking, make human eye be not enough to the effect of identification " previous row is in glimmer ".
Accompanying drawing explanation
Fig. 1 is the ranks sub-control driving circuit figure of the LED display of existing 1/4 scanning;
Fig. 2 is the ranks sub-control driving circuit figure of the utility model embodiment;
Embodiment
Below in conjunction with embodiment and contrast accompanying drawing the utility model is described.
The shadow circuit that disappears is lighted in the control nothing but for LED display as shown in Figure 2, is arranged in the horizontal drive circuit of LED display of 1/4 scanning ranks sub-control.Horizontal drive circuit comprises that the row that is provided with binary weighting address selects signal input part A0, the low effective row control line output terminal Y0 of A1 and mutual exclusion, Y1, Y2, the coding chip 74HC138 of Y3, and the two P channel mosfets 4953 that are connected with coding chip 74HC138, its inside comprises two independently, P-channel field-effect transistor (PEFT) pipe MOSFET1, MOSFET2, the control pin 2 of output terminal Y0 and field effect transistor MOSFET1, the grid G 1 that is field effect transistor MOSFET1 connects, the control pin 4 of output terminal Y1 and field effect transistor MOSFET1, the grid G 2 that is field effect transistor MOSFET1 connects, the control pin 2 of output terminal Y2 and field effect transistor MOSFET2, the grid G 1 that is field effect transistor MOSFET2 connects, the control pin 4 of output terminal Y3 and field effect transistor MOSFET2, the grid G 2 that is field effect transistor MOSFET2 connects, field effect transistor MOSFET1 be connected 7, 8 pin are line output terminal H1, field effect transistor MOSFET1 be connected 5, 6 pin are line output terminal H2, field effect transistor MOSFET2 be connected 7, 8 pin are line output terminal H3, field effect transistor MOSFET2 be connected 5, 6 pin are line output terminal H4, line output terminal H1, H2, H3 and H4 show light emitting diode D1 on concrete visual row with LED display respectively, D2, D3 is connected with D4, for 16 constant-current LED drive integrated circult U2 that list light emitting diode of driving LED display screen, inside have CMOS bit shift register and bolt-lock, the input data-switching of serial can be become to parallel data output format, the output current of all passages of drive integrated circult U2 is set by adjusting resistance BR1.
Control line output terminal Y0 is expert at, line output terminal H1 and publicly between be provided with the first transistor switching circuit, the first transistor switching circuit comprises the first triode Q1, the first coupling branch road that connecting is expert at is made up of the first isolation resistance RR1 and the first isolation capacitance C1 between control line output terminal Y0 and the first triode Q1 base stage, be connected to the first electrode resistance HR1 between the first triode Q1 base stage and emitter, and be connected to the first collector resistance NR1 between the first triode Q1 collector and line output terminal H1, row control line output terminal Y0 and be the input end of the first transistor switching circuit publicly, line output terminal H1 and be the output terminal of the first transistor switching circuit publicly,
When the row control line output terminal Y0 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the first isolation capacitance C1 both end voltage is " 0 ", select the ratio of the first isolation resistance RR1 and the first electrode resistance HR1, make the first triode Q1 saturation conduction, line output terminal H1 by the first collector resistance NR1 the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the first isolation capacitance C1, its both end voltage raises gradually, electric current by the first isolation capacitance C1 reduces gradually, until make the first triode Q1 cut-off, the first collector resistance NR1 i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y0 of coding chip 74HC138 is when exporting high level and become low level, the first isolation capacitance C1 electric discharge, to return to original state, the ON time of the first triode Q1 is exactly row power supply Tf fall time, select the resistance of the first isolation resistance RR1 and the first electrode resistance HR1 and the capacitance of the first isolation capacitance C1, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ",
Control line output terminal Y1 is expert at, line output terminal H2 and publicly between be provided with the second transistor switching circuit, the second transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, the second transistor switching circuit comprises the second triode Q2, the second coupling branch road that connecting is expert at is made up of the second isolation resistance RR2 and the second isolation capacitance C2 between control line output terminal Y1 and the second transistor base, be connected to the second electrode resistance HR2 between the second triode Q2 base stage and emitter, and be connected to the second collector resistance NR2 between the second triode Q2 collector and line output terminal H2, row control line output terminal Y1 and be the input end of the second transistor switching circuit publicly, line output terminal H2 and be the output terminal of the second transistor switching circuit publicly,
When the row control line output terminal Y1 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the second isolation capacitance C2 both end voltage is " 0 ", select the ratio of the second isolation resistance RR2 and the second electrode resistance HR2, make the second triode Q2 saturation conduction, line output terminal H2 by the second collector resistance NR2 the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the second isolation capacitance C2, its both end voltage raises gradually, electric current by the second isolation capacitance C2 reduces gradually, until make the second triode Q2 cut-off, the second collector resistance NR2 i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y1 of coding chip 74HC138 is when exporting high level and become low level, the second isolation capacitance C2 electric discharge, to return to original state, the ON time of the second triode Q2 is exactly row power supply Tf fall time, select the resistance of the second isolation resistance PR2 and the second electrode resistance HR2 and the capacitance of the second isolation capacitance C2, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ",
Control line output terminal Y2 is expert at, line output terminal H3 and publicly between be provided with the 3rd transistor switching circuit, the 3rd transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, the 3rd transistor switching circuit comprises the 3rd triode Q3, the 3rd coupling branch road that connecting is expert at is made up of the 3rd isolation resistance RR3 and the 3rd isolation capacitance C3 between control line output terminal Y2 and the 3rd triode Q3 base stage, be connected to the 3rd electrode resistance HR3 between the 3rd triode Q3 base stage and emitter, and be connected to the 3rd collector resistance NR3 between the 3rd triode Q3 collector and line output terminal H2, row control line output terminal Y2 and be the input end of the 3rd transistor switching circuit publicly, line output terminal H3 and be the output terminal of the 3rd transistor switching circuit publicly,
When the row control line output terminal Y2 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the 3rd isolation capacitance C3 both end voltage is " 0 " ", select the ratio of the 3rd isolation resistance RR3 and the 3rd electrode resistance HR3, make the 3rd triode Q3 saturation conduction, line output terminal H2 by the 3rd collector resistance NR3 the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the 3rd isolation capacitance C3, its both end voltage raises gradually, electric current by the 3rd isolation capacitance C3 reduces gradually, until make the 3rd triode Q3 cut-off, the 3rd collector resistance NR3 i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y2 of coding chip 74HC138 is when exporting high level and become low level, the 3rd isolation capacitance C3 electric discharge, to return to original state, the ON time of the 3rd triode Q3 is exactly row power supply Tf fall time, select the resistance of the 3rd isolation resistance PR3 and the 3rd electrode resistance HR3 and the capacitance of the 3rd isolation capacitance C3, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ",
Control line output terminal Y3 is expert at, line output terminal H4 and publicly between be provided with the 4th transistor switching circuit, the 4th transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, the 4th transistor switching circuit comprises the 4th triode Q4, the 4th coupling branch road that connecting is expert at is made up of the 4th isolation resistance RR4 and the 4th isolation capacitance C4 between control line output terminal Y3 and the 4th triode Q4 base stage, be connected to the 4th electrode resistance HR4 between the 4th triode Q4 base stage and emitter, and be connected to the 4th collector resistance NR4 between the 4th triode Q4 collector and line output terminal H4, row control line output terminal Y3 and be the input end of the 4th transistor switching circuit publicly, line output terminal H4 and be the output terminal of the 4th transistor switching circuit publicly,
When the row control line output terminal Y3 of coding chip 74HC138 is when output low level becomes high level, scan next line, can not suddenly change because of the 4th isolation capacitance C4 both end voltage is " 0 ", select the ratio of the 4th isolation resistance RR4 and the 4th electrode resistance HR4, make the 4th triode Q4 saturation conduction, line output terminal H2 by the 4th collector resistance NR4 the earthy resistance in not improved circuit row power supply is dragged down rapidly, along with the charging of the 4th isolation capacitance C4, its both end voltage raises gradually, electric current by the 4th isolation capacitance C4 reduces gradually, until make the 4th triode Q4 cut-off, the 4th collector resistance NR4 i.e. earthy resistance in not improved circuit disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, the non-control under the driving of power supply of being expert at is lighted, when the row control line output terminal Y3 of coding chip 74HC138 is when exporting high level and become low level, the 4th isolation capacitance C4 electric discharge, to return to original state, the ON time of the 4th triode Q4 is exactly row power supply Tf fall time, select the resistance of the 4th isolation resistance PR4 and the 4th electrode resistance HR4 and the capacitance of the 4th isolation capacitance C4, make Tf=30ns, there is Tn overlapping time that is about 30ns in the previous row in a two field picture and rear a line, approximate with Tf fall time of row power supply, even because LED electric leakage causes the non-control of some LED to be lighted, due to corresponding overlapping time, the overlapping ratio Tn/Tm of displaying time Tm of Tn and every row is very little, in people's vision, there will not be conditions of streaking, it is the effect that human eye is not enough to identification " previous row is in glimmer ".
The function of the first transistor switching circuit, the second transistor switching circuit, the 3rd transistor switching circuit and the 4th transistor switching circuit is as follows:
In the time scanning next line, the first transistor switching circuit, the second transistor switching circuit, the 3rd transistor switching circuit and the 4th transistor switching circuit are in saturation conduction state, when after row power supply Tf fall time of previous row, the first transistor switching circuit, the second transistor switching circuit, the 3rd transistor switching circuit and the 4th transistor switching circuit are in cut-off state, make the first collector resistance NR1, the second collector resistance NR2, the 3rd collector resistance NR3 and the 4th collector resistance NR4, be that earthy resistance in the circuit of original solution conditions of streaking disconnects and being connected publicly, guarantee same column other row LED not can by certain row LED of electric leakage and with certain row LED earthy resistance that be connected of electric leakage to forming publicly loop, effectively eliminate with listing the LED non-control under the driving of power supply of being expert at and light.
The first triode Q1, the second triode Q2, the 3rd triode Q3 and the 4th triode Q4, be that model is the low-power consumption NPN type switch triode of BC817, and cutoff frequency is at least 100MHz.
The first isolation resistance RR1, the second isolation resistance RR2, the 3rd isolation resistance RR3 and the 4th isolation resistance RR4, that resistance is the accurate chip fixed resistance that the pin of 220 ohm is processed into F type, excessive for Limited Current, avoid respectively burning the first triode Q1, the second triode Q2, the 3rd triode Q3 and the 4th triode Q4.
The first isolation capacitance C1, the second isolation capacitance C2, the 3rd isolation capacitance C3 and the 4th isolation capacitance C4, that capacitance is the ceramics isolation capacitance of 1000PF, the first isolation capacitance C1, the second isolation capacitance C2, the time that discharges and recharges of the 3rd isolation capacitance C3 and the 4th isolation capacitance C4 is respectively by the first isolation capacitance C1 and the first isolation resistance RR1, the second isolation capacitance C2 and the second isolation resistance RR2, the 3rd isolation capacitance C3 and the 3rd isolation resistance RR3 and the 4th isolation capacitance C4 and the 4th isolation resistance RR4 determine jointly, for precisely controlling respectively the first triode Q1, the second triode Q2, the ON time of the 3rd triode Q3 and the 4th triode Q4.
The first electrode resistance HR1, the second electrode resistance HR2, the 3rd electrode resistance HR3 and the 4th electrode resistance HR4, that resistance is the chip fixed resistance of 27K ohm, the first electrode resistance HR1, the second electrode resistance HR2, the 3rd electrode resistance HR3 and the 4th electrode resistance HR4, the first triode Q1 is respectively used to release, the second triode Q2, the base charge of the 3rd triode Q3 and the 4th triode Q4, make respectively the first isolation capacitance C1, the second isolation capacitance C2, the 3rd isolation capacitance C3 and the 4th isolation capacitance C4 return to original state and guarantee respectively the first triode Q1, the second triode Q2, the 3rd triode Q3 and the 4th triode Q4 are in cut-off state.
The first collector resistance NR1, the second collector resistance NR2, the 3rd collector resistance NR3 and the 4th collector resistance NR4, be that resistance is the chip fixed resistance of 220 ohm, it is to guarantee that respectively the first triode Q1, the second triode Q2, the 3rd triode Q3 and the 4th triode Q4 are in saturation conduction state that its resistance is selected.
Above content is in conjunction with concrete preferred implementation further detailed description of the utility model, can not assert that concrete enforcement of the present utility model is confined to these explanations.For the utility model person of an ordinary skill in the technical field; make without departing from the concept of the premise utility some alternative or obvious modification that are equal to; and performance or purposes identical, all should be considered as belonging to the utility model by the definite scope of patent protection of submitted to claims.
Claims (8)
1. the shadow circuit that disappears is lighted in the control nothing but for LED display, be arranged in the horizontal drive circuit of LED display of 1/4 scanning ranks sub-control, described horizontal drive circuit comprises that the row that is provided with binary weighting address selects signal input part A0, the low effective row control line output terminal Y0 of A1 and mutual exclusion, Y1, Y2, the coding chip 74HC138 of Y3, and the two P channel metal-oxide-semiconductor field MOSFET4953 that are connected with described coding chip 74HC138, its inside comprises two independently P-channel field-effect transistor (PEFT) pipe MOSFET1, MOSFET2, the control pin 2 of described output terminal Y0 and field effect transistor MOSFET1, the grid G 1 that is field effect transistor MOSFET1 connects, the control pin 4 of described output terminal Y1 and field effect transistor MOSFET1, the grid G 2 that is field effect transistor MOSFET1 connects, the control pin 2 of described output terminal Y2 and field effect transistor MOSFET2, the grid G 1 that is field effect transistor MOSFET2 connects, the control pin 4 of described output terminal Y3 and field effect transistor MOSFET2, the grid G 2 that is field effect transistor MOSFET2 connects, field effect transistor MOSFET1 be connected 7, 8 pin are line output terminal H1, field effect transistor MOSFET1 be connected 5, 6 pin are line output terminal H2, field effect transistor MOSFET2 be connected 7, 8 pin are line output terminal H3, field effect transistor MOSFET2 be connected 5, 6 pin are line output terminal H4, it is characterized in that:
At described row control line output terminal Y0, described line output terminal H1 and publicly between be provided with the first transistor switching circuit, described the first transistor switching circuit comprises the first triode, be connected to the first coupling branch road being formed by the first isolation resistance and the first isolation capacitance between described row control line output terminal Y0 and described the first transistor base, be connected to the first electrode resistance between described the first transistor base and emitter, and be connected to the first collector resistance between described the first transistor collector and described line output terminal H1, described row control line output terminal Y0 and be the input end of described the first transistor switching circuit publicly, described line output terminal H1 and be the output terminal of described the first transistor switching circuit publicly,
At described row control line output terminal Y1, described line output terminal H2 and publicly between be provided with the second transistor switching circuit, described the second transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, described the second transistor switching circuit comprises the second triode, be connected to the second coupling branch road being formed by the second isolation resistance and the second isolation capacitance between described row control line output terminal Y1 and described the second transistor base, be connected to the second electrode resistance between described the second transistor base and emitter, and be connected to the second collector resistance between described the second transistor collector and described line output terminal H2, described row control line output terminal Y1 and be the input end of described the second transistor switching circuit publicly, described line output terminal H2 and be the output terminal of described the second transistor switching circuit publicly,
At described row control line output terminal Y2, described line output terminal H3 and publicly between be provided with the 3rd transistor switching circuit, described the 3rd transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, described the 3rd transistor switching circuit comprises the 3rd triode, be connected to the 3rd coupling branch road being formed by the 3rd isolation resistance and the 3rd isolation capacitance between described row control line output terminal Y2 and described the 3rd transistor base, be connected to the 3rd electrode resistance between described the 3rd transistor base and emitter, and be connected to the 3rd collector resistance between described the 3rd transistor collector and described line output terminal H2, described row control line output terminal Y2 and be the input end of described the 3rd transistor switching circuit publicly, described line output terminal H3 and be the output terminal of described the 3rd transistor switching circuit publicly,
At described row control line output terminal Y3, described line output terminal H4 and publicly between be provided with the 4th transistor switching circuit, described the 4th transistor switching circuit is identical with composition and the components and parts of the first transistor switching circuit, described the 4th transistor switching circuit comprises the 4th triode, be connected to the 4th coupling branch road being formed by the 4th isolation resistance and the 4th isolation capacitance between described row control line output terminal Y3 and described the 4th transistor base, be connected to the 4th electrode resistance between described the 4th transistor base and emitter, and be connected to the 4th collector resistance between described the 4th transistor collector and described line output terminal H4, described row control line output terminal Y3 and be the input end of described the 4th transistor switching circuit publicly, described line output terminal H4 and be the output terminal of described the 4th transistor switching circuit publicly.
2. the shadow circuit that disappears is lighted in the control nothing but for LED display as claimed in claim 1, it is characterized in that:
Described the first triode, the second triode, the 3rd triode and the 4th triode are the NPN type switch triodes that cutoff frequency is at least 100MHz.
3. the shadow circuit that disappears is lighted in the control nothing but for LED display as claimed in claim 1 or 2, it is characterized in that:
Described the first triode, the second triode, the 3rd triode and the 4th triode are that model is the low-power consumption NPN type switch triode of BC817.
4. the shadow circuit that disappears is lighted in the control nothing but for LED display as claimed in claim 3, it is characterized in that:
Described the first isolation resistance, the second isolation resistance, the 3rd isolation resistance and the 4th isolation resistance are chip fixed resistances.
5. the shadow circuit that disappears is lighted in the control nothing but for LED display as claimed in claim 4, it is characterized in that:
Described the first isolation resistance, the second isolation resistance, the 3rd isolation resistance and the 4th isolation resistance are the accurate chip fixed resistances that pin is processed into F type.
6. the shadow circuit that disappears is lighted in the control nothing but for LED display as claimed in claim 5, it is characterized in that:
Described the first isolation capacitance, the second isolation capacitance, the 3rd isolation capacitance and the 4th isolation capacitance, be ceramics isolation capacitance, the time that discharges and recharges of described the first isolation capacitance, the second isolation capacitance, the 3rd isolation capacitance and the 4th isolation capacitance is determined jointly by described the first isolation capacitance and described the first isolation resistance, the second isolation capacitance and described the second isolation resistance, the 3rd isolation capacitance and described the 3rd isolation resistance and the 4th isolation capacitance and described the 4th isolation resistance respectively.
7. the shadow circuit that disappears is lighted in the control nothing but for LED display as claimed in claim 6, it is characterized in that:
Described the first electrode resistance, the second electrode resistance, the 3rd electrode resistance and the 4th electrode resistance are chip fixed resistances.
8. the shadow circuit that disappears is lighted in the control nothing but for LED display as claimed in claim 7, it is characterized in that:
Described the first collector resistance, the second collector resistance, the 3rd collector resistance and the 4th collector resistance are chip fixed resistances.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320628493.4U CN203596163U (en) | 2013-10-12 | 2013-10-12 | Shadow elimination circuit without non-controllable illumination used for LED display screen |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320628493.4U CN203596163U (en) | 2013-10-12 | 2013-10-12 | Shadow elimination circuit without non-controllable illumination used for LED display screen |
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| Publication Number | Publication Date |
|---|---|
| CN203596163U true CN203596163U (en) | 2014-05-14 |
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| CN201320628493.4U Expired - Fee Related CN203596163U (en) | 2013-10-12 | 2013-10-12 | Shadow elimination circuit without non-controllable illumination used for LED display screen |
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| CN (1) | CN203596163U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116189608A (en) * | 2022-02-16 | 2023-05-30 | 北京大学 | Method for eliminating phenomena of caterpillar and smear and improving refresh rate of LED display screen |
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2013
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116189608A (en) * | 2022-02-16 | 2023-05-30 | 北京大学 | Method for eliminating phenomena of caterpillar and smear and improving refresh rate of LED display screen |
| CN116189608B (en) * | 2022-02-16 | 2023-08-04 | 北京大学 | Method for eliminating phenomena of caterpillar and smear and improving refresh rate of LED display screen |
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