CN103926517B - The test device and method of power type LED thermal resistance - Google Patents

Abstract

The invention discloses the heat resistance test apparatus of a kind of power-type LED, including power-type LED, heating cooling unit, power supply/measuring unit, temperature control unit, optical parameter measurement unit and computer；Computer to the different electric current of power-type LED output and measures corresponding electrical power for controlling power supply/measuring unit；Computer controls, by controlling temperature control unit, the temperature value that heating cooling unit generation is different；Optical parametric test cell is used for gathering power-type LED optical parametric, and this optical parametric is transferred to computer is completed analytical calculation by computer；Power supply/measuring unit is connected with heating cooling unit, controls heating cooling unit for coupled computer and produces different temperature values.The present invention uses a kind of new measured power type LED heat resistance method, and the method is by obtaining efficiency junction temperature coefficient k_e, thermal power and electrical power conversion coefficient k_h, and LED external heat sink thermal resistance R_hsObtain the thermal resistance value of LED, reduce testing cost, simple to operate.

Description

The test device and method of power type LED thermal resistance

Technical field

The invention belongs to technical field of photoelectricity test, be specifically related to the method for testing of a kind of measured power type LED heat resistance.

Background technology

Power-type LED is the core devices of field of semiconductor illumination, but in LED normally works, has the electricity of more than 70% Heat energy can be converted into so that LED chip junction temperature significantly raises, have a strong impact on the photoelectric properties of LED, cause light output attenuatoin, Life-span minimizing, reliability reduction etc..It is thus desirable to the thermal characteristic parameters such as power type LED thermal resistance are tested quickly and accurately, Design parameter is provided for LED encapsulation and heat sink design and carries out effective heat management.

The method measuring LED heat characteristic the most both at home and abroad mainly has infrared thermography, spectrographic method, luminous power method, pin temperature Degree method and electrical parameter method.Electrical parameter method is linear with junction temperature based on LED two ends forward voltage drop, by being switched fast Measure electric current and obtain junction temperature with the change measuring terminal voltage when adding thermocurrent, be calculated LED heat resistance further.The method is not required to LED encapsulation structure to be destroyed, and certainty of measurement is high, speed is fast, is the most general standard method.But major defect Being that in electric current transformation process, thermal loss causes thermo-resistance measurement error relatively big, additionally on detection PN junction, the change of forward voltage needs The most high-precision data acquisition instrument, it is difficult to reduce R&D costs.

Summary of the invention

In consideration of it, it is an object of the invention to provide the method and device of a kind of new measured power type LED heat resistance, use the method The system cost that power type LED thermal resistance is tested can be effectively reduced with device, and simple to operate, there is certain engineer applied and be worth.

An object of the present invention is realized by such technical scheme, and the heat resistance test apparatus of power-type LED, including merit Rate type LED, heating cooling unit, power supply/measuring unit, temperature control unit, optical parameter measurement unit and computer；

Described computer exports different electric currents to power-type LED for controlling power supply/measuring unit and measures the electrical power of correspondence；

Described computer controls, by controlling temperature control unit, the temperature value that heating cooling unit generation is different；

Described optical parametric test cell is for gathering the optical parametric of power-type LED, and this optical parametric is transferred to computer Analytical calculation is completed by computer；

Described power supply/measuring unit is connected with heating cooling unit, controls heating cooling unit for coupled computer and produces different Temperature value.

Further, described heating cooling unit includes heat sink, semiconductor thermoelectric refrigeration sheet and the radiator being sequentially connected with；Described merit Rate type LED is arranged on heat sink, and described semiconductor thermoelectric refrigeration sheet is connected with temperature control unit.

Further, described optical parametric test cell is light collecting type parameter testing unit, described light collecting type optical parametric test cell Visiting device including light collecting device and light, described power-type LED is arranged at the light inlet of light collecting device, and described light detection device sets Put at the receipts light mouth of light collecting device；Described light collecting device is integrating sphere, and described light detection device is luminosity probe or radiation probe.

Further, described optical parametric test cell is non-light collecting type parameter testing unit, described non-light collecting type parameter testing unit Including light detection device, described light detection device is arranged on power-type LED optical axis；Described light detection device be luminosity probe or Radiation probe.

The thermo-resistance measurement method of power-type LED, measure power-type LED optical parametric to electrical power variation relation, wherein optics Parameter is total light flux, partial luminous flux, illuminance, luminous power, axial luminous power, axial illuminance, relative radiant intensity Etc. any one in parameter, and optical parametric-electric power curves is carried out nonlinear least-square matching, obtain optical parametric pole Electrical power at value；At power type LED thermal resistance and extreme value, the functional relation of electrical power is formula (1), obtains k further_e、k_h And R_hsThe value of three parameters, i.e. can get power type LED thermal resistance R_jc；

$R_{\mathrm{jc}}=-\frac{1}{2k_e{k}_h{P}_{d\max }}-R_{\mathrm{hs}}---\left(1\right)$

In formula (1), P_dmaxFor electrical power corresponding during optical parametric extreme value, k_eFor efficiency-junction temperature coefficient, k_hFor thermal power with The conversion coefficient of electrical power, R_jcFor the thermal resistance of power-type LED, R_hsFor the thermal resistance of LED external heat sink and known.

Further, it is thus achieved that P_dmaxMethod include following sub-step:

S61: computer controls power supply/measuring unit and exports different electric currents to power-type LED, utilizes power supply/measuring unit to record Electrical power P under different injection currents_d；Utilize optical parameter measurement unit to record optical parametric P simultaneously_O, obtain pass between the two It is curve P_O-P_d；

S62: optical parametric P_OWith electrical power P_dMeet formula (2) relation:

P_O=E_p0[P_d+k_ek_h(R_jc+R_hs)P_d ²] (2)

As optical parametric P_ODuring extreme value, electrical power P_dmaxCan be expressed as formula (3):

$P_{d\max }=-\frac{1}{2k_e{k}_h(R_{\mathrm{jc}}+R_{\mathrm{hs}})}---\left(3\right)$

Wherein E_p0It is T for ambient temperature₀Time optical parameter-electrical power efficiency, k_eFor efficiency-junction temperature coefficient, k_hFor thermal power with The conversion coefficient of electrical power, R_jcFor the thermal resistance of power-type LED, R_hsThermal resistance for LED external heat sink；

S63: according to formula (2), to P_O-P_dRelation curve carries out nonlinear least-square matching, obtains at optical parametric extreme value Electrical power P_dmax。

Further, it is thus achieved that k_hMethod include following sub-step:

S71: computer controls power supply/measuring unit and exports rated operational current to power-type LED, utilizes power supply/measuring unit to survey Obtain electrical power P under rated current_d；Optical parameter measurement unit is utilized to record luminous power P_L, utilize formula (4) to obtain thermal power Conversion coefficient k with electrical power_h；

$k_h=\frac{P_d-P_L}{P_d}---\left(4\right)$

Further, k is obtained_eMethod include following sub-step:

S81: computer controls power supply/measuring unit and exports suitable operating current to power-type LED so that LED can light But do not produce obvious heat effect；Utilize temperature control unit to control heating cooling unit and produce different temperature values；Utilize electricity Source/measuring unit measures electrical power P under different temperatures_d；Utilize optical parameter measurement unit to record optical parameter value P simultaneously_O, meter Calculation obtains optical parameter-electrical power efficiency E and junction temperature T_jRelation curve E-T_j；

S82: use the principle of least square to E-T_jCurve data carries out linear fit, obtains the coefficient value k of efficiency and junction temperature_e；

E=E_p0[1+k_e(T_j-T₀)] (5)

Wherein E is optical parameter-electrical power efficiency, E_p0It is T for ambient temperature₀Time optical parameter-electrical power efficiency.

Owing to have employed technique scheme, present invention have the advantage that:

1, using conventional measurement data to be analyzed, method is simple and workable, and data result is with a high credibility.

2, need not high-precision special data acquisition instrument, it is only necessary to conventional photoelectric measurement equipment, therefore needed for test into This is low, is very suitable for the engineer applied of enterprise.

Accompanying drawing explanation

In order to make the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, the present invention is made further Describe in detail, wherein:

Fig. 1 is test principle of device block diagram；

Fig. 2 is luminous flux-electrical power and light efficiency-junction temperature test philosophy figure；

Fig. 3 is that luminous flux is with electrical power change curve and matched curve figure；

Fig. 4 is light efficiency and variations injunction temperature curve and matched curve figure；

Wherein, 1, power-type LED；2, heat sink；3, semiconductor thermoelectric refrigeration sheet；4, radiator；5, heating cooling is single Unit；6, power supply/measuring unit；7, temperature control unit；8, integrating sphere；9, luminosity probe or radiation probe；10、 Optical parameter measurement unit；11, computer.

Detailed description of the invention

Below with reference to accompanying drawing, the preferred embodiments of the present invention are described in detail；Should be appreciated that preferred embodiment is only The explanation present invention rather than in order to limit the scope of the invention.

As shown in Figure 1, 2, the heat resistance test apparatus of power-type LED, including power-type LED 1, heating cooling unit 5, electricity Source/measuring unit 6, temperature control unit 7, optical parameter measurement unit 10 and computer 11；

Described computer exports different electric currents to power-type LED for controlling power supply/measuring unit and measures the electrical power of correspondence；

Described computer controls, by controlling temperature control unit, the temperature value that heating cooling unit generation is different；

Described optical parametric test cell is for gathering the optical parametric of power-type LED, and this optical parametric is transferred to computer Analytical calculation is completed by computer；Wherein optical parametric includes total light flux, partial luminous flux, illuminance, luminous power, axially Luminous power, axial illuminance, relative radiant intensity etc., optical parametric test cell 10 is used for gathering power-type in the present embodiment The total light flux of LED.

Described power supply/measuring unit is connected with heating cooling unit, controls heating cooling unit for coupled computer and produces different Temperature value.

Heat sink 2, semiconductor thermoelectric refrigeration sheet 3 that described heating cooling unit includes being sequentially connected with and radiator 4；Described power-type LED1 is arranged on heat sink, and described semiconductor thermoelectric refrigeration sheet is connected with temperature control unit.

In the present embodiment, optical parameter test cell is light collecting type parameter testing unit, in the present embodiment, uses integrating sphere 8 as collection Electro-optical device, uses luminosity probe 9 (or radiation probe) to visit device as light, and power-type LED is arranged on the light inlet of integrating sphere Place, luminosity probe (or radiation probe) is arranged at the receipts light mouth of integrating sphere.

Certainly non-light collecting type optical parametric test cell is used also can to realize the collection to power-type LED optical parametric, non-when gathering The when of the test of light collecting type optical parametric, only luminosity probe 9 (or radiation probe) need to be arranged on power-type LED optical axis.

Use above-mentioned test device to carry out the method that power type LED thermal resistance carries out testing, measure power-type LED optical parametric pair Electrical power variation relation, optical parametric P_OIt is chosen for total light flux Φ_v, and total light flux-electric power curves is carried out least square Nonlinear fitting, obtains the electrical power at total light flux extreme value.The functional relation of electrical power at power type LED thermal resistance and extreme value For formula (1), obtain k further_e、k_hAnd R_hsThe value of three parameters, i.e. can get power type LED thermal resistance R_jc；

$R_{\mathrm{jc}}=-\frac{1}{2k_e{k}_h{P}_{d\max }}-R_{\mathrm{hs}}---\left(1\right)$

In formula (1), P_dmaxFor electrical power corresponding during optical parametric extreme value, k_eFor efficiency-junction temperature coefficient, k_hFor thermal power with The conversion coefficient of electrical power, R_jcFor the thermal resistance of power-type LED, R_hsFor the thermal resistance of LED external heat sink and known.

Obtain P_dmaxMethod include following sub-step:

Computer 11 controls power supply/measuring unit (SMU) 6 and exports different electric currents to power-type LED, utilizes SMU to survey Obtain electrical power P under different injection currents_d；Utilize optical parameter measurement unit to record total light flux Φ simultaneously_v, obtain between the two Relation curve Φ_v-P_d。

Luminous flux phi_vWith electrical power P_dMeet formula (2) functional relationship.

Φ_v=E_p0[P_d+k_ek_h(R_jc+R_hs)P_d ²] (2)

As total light flux Φ_vDuring extreme value, electrical power P_dmaxFormula (3) can be expressed as.

$P_{d\max }=-\frac{1}{2k_e{k}_h(R_{\mathrm{jc}}+R_{\mathrm{hs}})}---\left(3\right)$

Wherein E_p0It is T for ambient temperature₀Time total light flux-electrical power efficiency, k_eFor efficiency-junction temperature coefficient, k_hFor thermal power With the conversion coefficient of electrical power, R_jcFor the thermal resistance of power-type LED, R_hsThermal resistance for LED external heat sink.

According to formula (2), to Φ_v-P_dRelation curve carries out nonlinear least-square matching, obtains the electrical power at total light flux extreme value P_dmax, its luminous flux is with electrical power change curve as shown in Figure 3.

Obtain k_hMethod include following sub-step:

Computer 11 controls power supply/measuring unit (SMU) 6 and exports rated operational current to power-type LED, utilizes SMU Record electrical power P under rated current_d；Luminosity probe is replaced with radiation probe, records luminous power P_L, utilize formula (4) to obtain Conversion coefficient k to thermal power Yu electrical power_h。

$k_h=\frac{P_d-P_L}{P_d}---\left(4\right)$

Obtain k_eMethod include following sub-step:

Computer 11 controls power supply/measuring unit (SMU) 6 and exports 5mA operating current to power-type LED.Utilize temperature control Unit 7 processed controls heating cooling unit 5 and produces 40 DEG C, 50 DEG C, 60 DEG C, 70 DEG C, the different temperatures values such as 80 DEG C.Utilize SMU Measure electrical power P under different temperatures_d；Utilize optical parameter measurement unit to record total light flux Φ simultaneously_v, it is calculated total light flux Φ_v-electrical power efficiency E (total light flux/electrical power) and junction temperature T_jRelation curve E-T_j。

Use the principle of least square to E-T_jCurve data carries out linear fit, obtains the coefficient value k of efficiency and junction temperature_e。

E=E_p0[1+k_e(T_j-T₀)] (5)

Its light efficiency is with variations injunction temperature curve as shown in Figure 4.

Utilizing formula (3) to obtain power type LED thermal resistance is formula (6), by R_hs、k_h、k_eSubstitute into, thermal resistance value can be calculated. In this example, the power type LED thermal resistance value recorded be 9.2 (DEG C/W), nominal thermal resistance value be 8 (DEG C/W).

$R_{\mathrm{jc}}=-\frac{1}{2k_e{k}_h{P}_{d\max }}-R_{\mathrm{hs}}---\left(6\right)$

The present invention uses a kind of method that new measured power type LED heat hinders, and the method is by obtaining efficiency-junction temperature coefficient k_e, Thermal power and the conversion coefficient k of electrical power_h, and be thermal resistance R of LED external heat sink_hsObtain the thermal resistance of power-type LED Value, reduces cost of testing system, and simple to operate, has certain engineer applied and is worth.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, it is clear that those skilled in the art can The present invention is carried out various change and modification without departing from the spirit and scope of the present invention.So, if these of the present invention are repaiied Change and belong within the scope of the claims in the present invention and equivalent technologies thereof with modification, then the present invention is also intended to comprise these changes and become Including type.

Claims (8)

1. the heat resistance test apparatus of a power-type LED, it is characterised in that: include power-type LED, heating cooling unit, Power supply/measuring unit, temperature control unit, optical parametric test cell and computer；

Described computer exports different electric currents to power-type LED for controlling power supply/measuring unit and measures the electrical power of correspondence；

Described computer controls, by controlling temperature control unit, the temperature value that heating cooling unit generation is different；

Described optical parametric test cell is for gathering the optical parametric of power-type LED, and this optical parametric is transferred to computer Analytical calculation is completed by computer,

Computer measurement power-type LED optical parametric is to electrical power variation relation, and wherein optical parametric is total light flux, part light Any one in flux, illuminance, luminous power, axial luminous power, axial illuminance, relative radiant intensity parameter, and right Optical parametric-electric power curves carries out nonlinear least-square matching, obtains the electrical power at optical parametric extreme value；Power-type LED At thermal resistance and extreme value, the functional relation of electrical power is formula (1), obtains k further_e、k_hAnd R_hsThe value of three parameters, To power type LED thermal resistance R_jc；

$R_{jc}=-\frac{1}{2k_e{k}_h{P}_{dmax}}-R_{hs}---\left(1\right)$

In formula (1), P_dmaxFor electrical power corresponding during optical parametric extreme value, k_eFor efficiency-junction temperature coefficient, k_hFor thermal power with The conversion coefficient of electrical power, R_jcFor the thermal resistance of power-type LED, R_hsFor the thermal resistance of LED external heat sink and known；

Described power supply/measuring unit is connected with heating cooling unit, controls heating cooling unit for coupled computer and produces different Temperature value.

The heat resistance test apparatus of power-type LED the most according to claim 1, it is characterised in that: described heating cooling is single Unit includes heat sink, semiconductor thermoelectric refrigeration sheet and the radiator being sequentially connected with；Described power-type LED is arranged on heat sink, Described semiconductor thermoelectric refrigeration sheet is connected with temperature control unit.

The heat resistance test apparatus of power-type LED the most according to claim 1, it is characterised in that: described optical parametric is surveyed Examination unit is light collecting type parameter testing unit, and described light collecting type parameter testing unit includes light collecting device and light detection device, Described power-type LED is arranged at the light inlet of light collecting device, and described light detection device is arranged on the receipts light mouth of light collecting device Place；Described light collecting device is integrating sphere, and described light detection device is luminosity probe or radiation probe.

The heat resistance test apparatus of power-type LED the most according to claim 1, it is characterised in that: described optical parametric is surveyed Examination unit is non-light collecting type parameter testing unit, and described non-light collecting type parameter testing unit includes light detection device, described light Detection device is arranged on power-type LED optical axis；Described light detection device is luminosity probe or radiation probe.

5. the thermo-resistance measurement method of a power-type LED, it is characterised in that: measure power-type LED optical parametric to electrical power Variation relation, wherein optical parametric is total light flux, partial luminous flux, illuminance, luminous power, axial luminous power, axle Any one in illuminance, relative radiant intensity parameter, and it is non-that optical parametric-electric power curves is carried out least square Linear fit, obtains the electrical power at optical parametric extreme value；The functional relationship of electrical power at power type LED thermal resistance and extreme value Formula is formula (1), obtains k further_e、k_hAnd R_hsThe value of three parameters, i.e. can get power type LED thermal resistance R_jc；

$R_{jc}=-\frac{1}{2k_e{k}_h{P}_{dmax}}-R_{hs}---\left(1\right)$

In formula (1), P_dmaxFor electrical power corresponding during optical parametric extreme value, k_eFor efficiency-junction temperature coefficient, k_hFor thermal power with The conversion coefficient of electrical power, R_jcFor the thermal resistance of power-type LED, R_hsFor the thermal resistance of LED external heat sink and known.

The thermo-resistance measurement method of power-type LED the most according to claim 5, it is characterised in that: obtain P_dmaxMethod Including following sub-step:

S61: computer controls power supply/measuring unit and exports different electric currents to power-type LED, utilizes power supply/measuring unit to record Electrical power P under different injection currents_d；Utilize optical parametric test cell to record optical parametric P simultaneously_O, obtain between the two Relation curve P_O-P_d；

S62: optical parametric P_OWith electrical power P_dMeet formula (2) relation:

P_O=E_p0[P_d+k_ek_h(R_jc+R_hs)P_d ²] (2)

As optical parametric P_ODuring extreme value, electrical power P_dmaxCan be expressed as formula (3):

$P_{d\max }=-\frac{1}{2k_e{k}_h(R_{jc}+R_{hs})}---\left(3\right)$

Wherein E_p0It is T for ambient temperature₀Time optical parameter-electrical power efficiency, k_eFor efficiency-junction temperature coefficient, k_hFor thermal power with The conversion coefficient of electrical power, R_jcFor the thermal resistance of power-type LED, R_hsThermal resistance for LED external heat sink；

S63: according to formula (2), to P_O-P_dRelation curve carries out nonlinear least-square matching, obtains at optical parametric extreme value Electrical power P_dmax。

The thermo-resistance measurement method of power-type LED the most according to claim 6, it is characterised in that: obtain k_hMethod bag Include following sub-step:

S71: computer controls power supply/measuring unit and exports rated operational current to power-type LED, utilizes power supply/measuring unit to survey Obtain electrical power P under rated current_d；Optical parametric test cell is utilized to record luminous power P_L, utilize formula (4) to obtain heat Power and the conversion coefficient k of electrical power_h；

$k_h=\frac{P_d-P_L}{P_d}---\left(4\right).$

The thermo-resistance measurement method of power-type LED the most according to claim 6, it is characterised in that: obtain k_eMethod bag Include following sub-step:

S81: computer controls power supply/measuring unit and exports suitable operating current to power-type LED so that power-type LED But can light and not produce obvious heat effect；Utilize temperature control unit to control heating cooling unit and produce different temperature Value；Power supply/measuring unit is utilized to measure electrical power P under different temperatures_d；Utilize optical parametric test cell to record optics simultaneously Parameter P_O, it is calculated optical parameter-electrical power efficiency E and junction temperature T_jRelation curve E-T_j；

S82: use the principle of least square to E-T_jCurve data carries out linear fit, obtains efficiency-junction temperature coefficient k_e；

E=E_p0[1+k_e(T_j-T₀)] (5)

Wherein E is optical parameter-electrical power efficiency, E_p0It is T for ambient temperature₀Time optical parameter-electrical power efficiency.