CN202758058U

CN202758058U - LED failure value detection circuit

Info

Publication number: CN202758058U
Application number: CN201220426267.3U
Authority: CN
Inventors: 刘云霞; 刘海鹏
Original assignee: ANBANG ELECTRIC Co Ltd WUXI
Current assignee: WUXI ANBANG ELECTRIC CO Ltd
Priority date: 2012-08-27
Filing date: 2012-08-27
Publication date: 2013-02-27
Anticipated expiration: 2022-08-27

Abstract

The utility model relates to a detection circuit, and especially relates to a LED failure value detection circuit, which belongs to the LED failure detection technical field. According to the technical scheme provided by the utility model, the LED failure value detection circuit comprises a power supply output module used for providing work power supply and several LED luminescence branches, wherein the LED luminescence branches comprise a LED light source and a sampling resistor; and the LED failure value detection circuit also comprises a CPLD processing module, the CPLD processing module collects the current of the LED luminescence branches through the sampling resistor, and the output end of the CPLD processing module is connected with a power supply output module. According to the utility model, the LED failure value detection circuit can detect multi-strip LED branches, the low of the CPLD processing module is low, the sampling I/O port number is not limited, and the LED failure value detection circuit has good detection protection, better economic performance and strong practicality on a LED signal lamp having failure protection, and the adaptation scope is wide.

Description

LED stale value testing circuit

Technical field

The utility model relates to a kind of testing circuit, and especially a kind of LED stale value testing circuit belongs to the technical field of LED failure detection.

Background technology

For a long time, traffic lights all adopt high-power incandescent lamp as light source, join a colored lens and become the reddish yellow green signal light, but incandescent lamp power is large, cost is high, serviceable life is short, bring the line service amount large, the LED traffic lights had appearred in the last few years, its inner LED luminosity scale that adopts is as light source, low, the long service life of LED signal lamp advantage power, but the signal lamp luminosity scale of general requirements will be comprised of the hundreds of LEDs at least, usually be connected into a branch road by several LED, formed by several branch circuit parallel connections again.If LED inefficacy number is many, the driving car owner may judge the signal light color by accident and cause traffic hazard, for avoiding this situation, must add the LED failure detection circuit, reaches setting when LED loses efficacy, and testing circuit must be exported corresponding detection signals and take safeguard measure.For example the LED signal lamp requires inefficacy 50% to be protected, and this light fixture LED luminosity scale is comprised of 8 parallel branches, and when having detected 4 branch circuit break, testing circuit must take measures to be protected.

Summary of the invention

The purpose of this utility model is to overcome the deficiencies in the prior art, and a kind of LED stale value testing circuit is provided, and its compact conformation can detect wide accommodation to many LED branch roads simultaneously.

According to the technical scheme that the utility model provides, described LED stale value testing circuit comprises that the luminous branch road of described LED comprises led light source and sampling resistor be used to the power supply output module that working power is provided and the luminous branch road of some LED; Also comprise the CPLD processing module, described CPLD processing module is by the electric current of the luminous branch road of sampling resistor collection LED, and the output terminal of CPLD processing module links to each other with the power supply output module.

Described CPLD processing module comprises negate circuit, adding circuit and logic judging circuit.

Advantage of the present utility model: compact conformation, can detect many LED branch roads simultaneously, CPLD processing module cost is low, and sampled I/O mouth number is difficult for restricted; LED signal lamp with fail safe had preferably detection protection, very good economy, extremely strong practicality, wide accommodation.

Description of drawings

Fig. 1 is the schematic diagram of existing failure detection circuit.

Fig. 2 is circuit theory diagrams of the present utility model.

Fig. 3 is the structure principle chart in the utility model CPLD processing module.

Embodiment

The utility model is described in further detail below in conjunction with concrete drawings and Examples.

As shown in Figure 1: link to each other with the power supply output module behind the luminous branch circuit parallel connection of some LED, the input end of power supply output module links to each other with the 220V alternating voltage, and the required operating voltage of the output luminous branch road of LED, the power supply output module links to each other with MCU sampling processing module, and MCU sampling processing module is according to the duty of the working state control power supply output module of the luminous branch road of LED.Wherein, the luminous branch road of LED comprises some LED and sampling resistor R*, and sampling resistor R* is converted to information of voltage with the current information of the luminous branch road of place LED and offers MCU sampling processing module, so that whether detect the luminous branch road of place LED normal.

MCU sampling processing module gathers every string branch voltage; through the ADC(analog to digital conversion in the MCU sampling processing module) converter; judge the luminous branch circuit break inefficacy of lamp plate LED number; if reach percentage of failures; then MCU sampling processing module output control signal allows the power supply output module shield.But there is defective in this circuit, if the luminous number of branches of the LED of signal lamp luminosity scale is more, and that MCU sampling processing module has the sample port of ADC converter is limited, can't satisfy than multiple parallel branches, still circuit is improved, remedy this defective with the CPLD processing module, as shown in Figure 2.CPLD processing module (Complex Programmable Logic Device) mainly is by FPGA (Field Programmable Gate Array) macroelement (MC, Macro Cell) the programmable interconnect matrix unit around the center forms, wherein the MC structure is complicated, and has complicated I/O (I/O) cell interconnection structure, can generate as required specific circuit structure by the user, finish certain function, according to this CPLD processing module characteristic, we carry out following transformation

Utilize the I/O resource of CPLD processing module abundance, the I/O mouth to branch voltage sample laggard row operation process, if reach percentage of failures, just export control signal and allow the power module protection.Certainly the CPLD processing module will have the processing arithmetic capability, we need adopt schematic diagram or hardware description language that it is programmed, make it have the voluntarily digital integrated circuit of constitutive logic function, in the embodiment of the invention, we adopt schematic diagram to programme, then by download cable code is sent in the CPLD objective chip, allows the CPLD processing module have to open circuit the ability of number of branches.

As shown in Figure 3: be the structural representation in the utility model CPLD processing module, can realize opening circuit and detect and failure ratio is carried out logical operation that CPLD processing module input circuit detects judgement to three paths of LEDs branch roads respectively among Fig. 3; The CPLD processing module mainly is comprised of three large module digital integrated circuits, is respectively negate circuit, adding circuit, logic judging circuit.At first, article 3, input sample voltage is input to the I/O mouth of CPLD processing module, if there is the luminous branch road of LED to occur opening circuit, then the input sample voltage of corresponding branch road is 0, through becoming 1 after the negate of negate circuit, adding circuit is to three input (A, B, CI) carry out additive operation, addition value is by output terminal S after the computing, output terminal CO output, judge by logic judging circuit again, judgment value is exported high (or low) level by the I/O mouth of CPLD processing module at last, height (or low) level of output is controlled power supply output module duty again, thereby shields; Comprise AND circuit and OR circuit in the logic judging circuit.In the example, have the CPLD processing module that 3 tunnel inputs are arranged, lost efficacy to require to reach 60% protection, then when 2 branch circuit break occurring, the output out of CPLD processing module requirement is 1, and logic judging circuit is right 〉=and 2 numerical value judges, realized this function.Only be input as example with 3 the tunnel in this example and tell about, for more I/0 mouth sampling inputs, principle is identical, and only totalizer wants cascade to realize.

The utility model CPLD processing module cost is low, and sampled I/O mouth number is difficult for restricted; LED signal lamp with fail safe had preferably detection protection, very good economy, extremely strong practicality.

Claims

1. a LED stale value testing circuit comprises that be used to the power supply output module that working power is provided and the luminous branch road of some LED, the luminous branch road of described LED comprises led light source and sampling resistor (R*); It is characterized in that: also comprise the CPLD processing module, described CPLD processing module is by the electric current of the luminous branch road of sampling resistor (R*) collection LED, and the output terminal of CPLD processing module links to each other with the power supply output module.

2. LED stale value testing circuit according to claim 1, it is characterized in that: described CPLD processing module comprises negate circuit, adding circuit and logic judging circuit.