CN102750897A

CN102750897A - Simple test circuit for LED (light emitting diode) display module

Info

Publication number: CN102750897A
Application number: CN201210240956XA
Authority: CN
Inventors: 陈虎; 陈志伟
Original assignee: ECU ELECTRONICS INDUSTRIAL Co Ltd
Current assignee: ECU ELECTRONICS INDUSTRIAL Co Ltd
Priority date: 2012-07-12
Filing date: 2012-07-12
Publication date: 2012-10-24
Anticipated expiration: 2032-07-12
Also published as: CN102750897B

Abstract

The invention relates to a simple test circuit for an LED (light emitting diode) display module, comprising a constant flow source circuit, wherein the constant flow source circuit is connected with a cathode of the LED display module to be tested, a pulse generating circuit is connected with an anode of the LED display module to be tested by a switch circuit, and the constant flow source circuit powers the pulse generating circuit and the switch circuit. The simple test circuit adopts the pulse generating circuit, so that all LEDs can be 'simultaneously' turned on only by setting the frequency of a pulse signal to be more than the frequency (36Hz) which can not be distinguished by human eyes; and the LED display module to be tested is powered by the single constant flow source circuit, and all the LEDs within each region of the LED display module to be tested are accessed into a single constant flow source, so that the electric current passing through each LED can be guaranteed at a fixed value, and testers can quickly find out blind points and judge whether the LED display module to be tested has the phenomenon of uneven luminescence.

Description

A kind of simple and easy LED display module test circuit

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Technical field

The present invention relates to a kind of test circuit, especially a kind of simple and easy LED display module test circuit.

Background technology

Along with the strictness of the energy and cost is considered, the charactron that extensively applies in the household electrical appliances display panel is eliminated gradually, the substitute is signifying green, light emitting diode (LED) efficiently.These LED particles or and or be series at circuit, as shown in Figure 1, reach the display effect of special pattern again through software control.

LED is no doubt green, efficient, and whether a difficult problem is but how manufacturer lights LED according to the parameter of setting, thereby judge blind spot and check luminous even.LED needs constant-current driving, and its brightness is by the electric current decision through himself, yet what obtain easily in the laboratory is source of stable pressure, so common way is the source of stable pressure resistance in series.For circuit shown in Figure 1, can ABCDEFGH be connected as negative pole, 12345678 connect as anodal after the resistance in series respectively.Because the parameter of LED is variant, and arrangement mode is different, and 1 district is two LED particle series connection; Only there is a LED particle in 2 districts, and have in 1 district resistance in series is arranged simultaneously, like this if seek out stable constant current source; Just need the resistance of each district institute crosstalk resistance of constantly adjustment, be unfavorable for realizing.Its control procedure can be with reference to Fig. 2.

Moreover supposition can guarantee the electric current that obtains to envision through the adjustment of complicacy, for above-mentioned circuit, is example with 1 district, because different diode drops is different, (cause the reason of this phenomenon to have two: one, foozle, the LED wafer is impossible in full accord; Other reason is that the LED particle in 1 district possibly exist color distortion; Like 1A is red; 1B is green); Just mean allocation is on each LED particle fully for the electric current that is added in 1 district like this, and the result who causes is that brightness is inconsistent or can't get a desired effect, and makes troubles for the manufacturing of product or check.

Summary of the invention

The object of the present invention is to provide a kind of can the LED particle in the LED display module being lighted simultaneously, and the electric current that guarantees to flow through each LED particle is the simple and easy LED display module test circuit of the numerical value of customer requirements.

For realizing above-mentioned purpose; The present invention has adopted following technical scheme: a kind of simple and easy LED display module test circuit; Comprise constant-current source circuit; Constant-current source circuit links to each other with the negative pole of LED display module to be tested, and pulse generating circuit links to each other with the positive pole of LED display module to be tested through on-off circuit, and constant voltage power supply circuit is supplied power to pulse generating circuit and on-off circuit.

Can know that by technique scheme the present invention adopts pulse generating circuit, only need more than the frequency (36Hz) that human eye can't be differentiated, can be lighted the frequency configuration of pulse signal with all LED " simultaneously "; Adopt single constant-current source circuit that LED display module to be tested is supplied power; Each all LED in zone of LED display module to be tested all inserts single constant current source; The electric current of each LED is a fixed value thereby assurance is flowed through, and is convenient to the tester and finds out blind spot rapidly and judge whether LED display module to be tested exists the phenomenon of non-uniform light.

Description of drawings

Fig. 1 is a LED display module schematic diagram for example;

Fig. 2 is the source of stable pressure resistance in series test circuit that LED display module shown in Figure 1 is tested;

Fig. 3,4,5, the 6th, the circuit theory diagrams of constant-current source circuit, pulse generating circuit, on-off circuit, constant voltage power supply circuit among the present invention.

Embodiment

A kind of simple and easy LED display module test circuit; Comprise constant-current source circuit 1; Constant-current source circuit 1 links to each other with the negative pole of LED display module 5 to be tested; Pulse generating circuit 2 links to each other with the positive pole of LED display module 5 to be tested through on-off circuit 3, and constant voltage power supply circuit 4 is supplied power to pulse generating circuit 2 and on-off circuit 3, and is as shown in Figure 5.

As shown in Figure 3; Described constant-current source circuit 1 comprises diode D1; The negative electrode of diode D1 links to each other with the anode of diode D2, and the negative electrode of diode D2 links to each other with an end of resistance R 2, the base stage of triode Q1 respectively, the equal ground connection of collector of the other end of resistance R 2, triode Q1; The emitter of triode Q1 links to each other with an end of resistance R 1, the negative pole of the LED display module 5 of reception test after the other end of resistance R 1 links to each other with the anode of diode D1.Wherein, the size of the electric current of constant-current source circuit 1 output can realize through the resistance of regulating resistance R 1.

As shown in Figure 4; Described pulse generating circuit 2 comprises counter U1; Its 8th, 12 pin ground connection, its 9th, 10,11 pin links to each other with an end of capacitor C 4, resistance R 22, resistance R 21 respectively, the other end parallel connection of capacitor C 4, resistance R 22, resistance R 21; 4,5,6,7 pins of counter U1 link to each other with A, B, C, the D pin of code translator U2 respectively; The output terminal of described three terminal regulator U3 links to each other with the 16th pin of counter U1, the VCC pin of code translator U2 respectively, and the 1st, 2,3,4,5,6,7,9,10,11 pins of code translator U2 link to each other with the end of resistance R 3～R12 respectively, and the other end of resistance R 3～R12 links to each other with the base stage of triode Q2～Q11 respectively; The grounded emitter of triode Q2～Q11, the collector of triode Q2～Q11 links to each other with the input end of on-off circuit 3.

As shown in Figure 6, described constant voltage power supply circuit 4 comprises three terminal regulator U3, the input termination constant pressure source VCC of three terminal regulator U3, and the output terminal of three terminal regulator U3 links to each other with on-off circuit 3 with pulse generating circuit 2 respectively.Constant pressure source VCC provide input voltage; Supply counter U1 and code translator U2 to use through the stable back of three terminal regulator U3 output+5V direct current; The alternate conduction signal that code translator U2 sends drives triode Q2～Q11 alternate conduction; To produce one group of pulse voltage of anti-phase with it at a～j lead end like this, this pulse voltage will be used for driving switch circuit 3.

As shown in Figure 5; Described on-off circuit 3 comprises triode Q12; The output terminal of pulse generating circuit 2 links to each other with the base stage of triode Q12 through resistance R 13; The collector of triode Q12 connects the output terminal of said three terminal regulator U3 through resistance R 13, and the emitter of triode Q12 links to each other with the positive pole of LED display module 5 to be tested.The pulse signal that on-off circuit 3 utilizes pulse generating circuit 2 to send is controlled turning on and off of triode Q12.

When test; Constant-current source circuit 1 is inserted negative wire end A, B, C, D, E, F, G, the H of LED display module 5 to be tested respectively; The

positive wire end

1,2,3,4,5,6,7,8 of LED display module 5 to be tested is connected with on-off circuit 3 respectively; Another level of all on-off circuits 3, promptly the collector of triode Q12 meets source of stable pressure VCC.

After the circuit connection; The on-off circuit 3 that the

positive wire end

1,2,3,4,5,6,7,8 of LED display module 5 to be tested is connect will be open-minded in turn; Each regional LED of LED display module 5 to be tested also will light in turn; The frequency configuration of the pulse signal a that only needs pulse generating circuit 2 is sent, b, c, d, e, f, g, h, l, j can be lighted all LED " simultaneously " more than the frequency (36Hz) that human eye can't be differentiated.Because each all LED in zone all inserts single constant-current source circuit 1, thereby the electric current of each LED that guaranteed to flow through is a fixed value, is convenient to the tester and finds out blind spot rapidly and judge whether LED display module to be tested 5 exists the phenomenon of non-uniform light.

Claims

1. simple and easy LED display module test circuit; It is characterized in that: comprise constant-current source circuit (1); Constant-current source circuit (1) links to each other with the negative pole of LED display module (5) to be tested; Pulse generating circuit (2) links to each other with the positive pole of LED display module (5) to be tested through on-off circuit (3), and constant voltage power supply circuit (4) is supplied power to pulse generating circuit (2) and on-off circuit (3).

2. simple and easy LED display module test circuit according to claim 1; It is characterized in that: described constant-current source circuit (1) comprises diode D1; The negative electrode of diode D1 links to each other with the anode of diode D2; The negative electrode of diode D2 links to each other with an end of resistance R 2, the base stage of triode Q1 respectively; The equal ground connection of the collector of the other end of resistance R 2, triode Q1, the emitter of triode Q1 links to each other with an end of resistance R 1, the negative pole of the LED display module (5) of reception test after the other end of resistance R 1 links to each other with the anode of diode D1.

3. simple and easy LED display module test circuit according to claim 1; It is characterized in that: described constant voltage power supply circuit (4) comprises three terminal regulator U3; The input termination constant pressure source VCC of three terminal regulator U3, the output terminal of three terminal regulator U3 link to each other with on-off circuit (3) with pulse generating circuit (2) respectively.

4. simple and easy LED display module test circuit according to claim 2; It is characterized in that: described pulse generating circuit (2) comprises counter U1; Its 8th, 12 pin ground connection; Its 9th, 10,11 pin links to each other with an end of capacitor C 4, resistance R 22, resistance R 21 respectively; The other end parallel connection of capacitor C 4, resistance R 22, resistance R 21,4,5,6,7 pins of counter U1 link to each other with A, B, C, the D pin of code translator U2 respectively, and the output terminal of described three terminal regulator U3 links to each other with the 16th pin of counter U1, the VCC pin of code translator U2 respectively; The 1st, 2,3,4,5,6,7,9,10,11 pins of code translator U2 link to each other with the end of resistance R 3～R12 respectively; The other end of resistance R 3～R12 links to each other with the base stage of triode Q2～Q11 respectively, the grounded emitter of triode Q2～Q11, and the collector of triode Q2～Q11 links to each other with the input end of on-off circuit (3).

5. simple and easy LED display module test circuit according to claim 3; It is characterized in that: described on-off circuit (3) comprises triode Q12; The output terminal of pulse generating circuit (2) links to each other with the base stage of triode Q12 through resistance R 13; The collector of triode Q12 connects the output terminal of said three terminal regulator U3 through resistance R 13, and the emitter of triode Q12 links to each other with the positive pole of LED display module (5) to be tested.