TWI605730B - Light-emitting device with a temperature compensation element - Google Patents

Description

Light-emitting device with temperature compensating element

The invention relates to a light-emitting device, in particular comprising a switching element connected between a temperature compensating element and a group of light-emitting diodes.

Incandescent lamps emit light due to heat. Conversely, the light-emitting mechanism of a light-emitting diode (LED) is a combination of electrons and holes, and thus the light-emitting diode is called a cold light source.

In addition, the light-emitting diode has the advantages of high durability, long life, light weight, low power consumption, etc., so the current lighting market has high hopes for the light-emitting diode, and it is gradually replaced as a new generation of lighting tools. Light source, and is used in various fields, such as traffic signs, backlight modules, street lighting, medical equipment, etc.

In the field of lighting applications, it is generally necessary to make the light-emitting diode produce a spectrum of near-sunlight (white light) to match the human eye vision habit. The foregoing white light application may be made up of three primary colors of red, blue and green light, and the operating current is adjusted by the circuit design, and the white light is mixed according to different proportions. Due to the high cost of the circuit module and the complicated circuit design, this application is not currently popular. In addition, red, green, and blue phosphors can be excited by ultraviolet spectrum light-emitting diodes (UV-LEDs) to emit red, green, and blue light, and then mixed into white light. However, due to the current luminous efficiency of UV-LEDs to be improved, it has not been widely used in product applications.

However, when current is input into the light-emitting diode, in addition to the power-light energy conversion mechanism, a part of the electrical energy is converted into heat energy, which causes a change in many photoelectric characteristics. Fig. 1 is a graph showing the photoelectric characteristics of the blue light and the red light emitting diode when the junction temperature (Tj) of the light emitting diode is raised from 20 ° C to 80 ° C; wherein the vertical axis shows when the light is emitted The relative value of the photoelectric characteristic value at the junction temperature and the junction temperature of 20 ° C, for example, including the light output power (Po), the wavelength shift amount (Wd), and the forward voltage value ( Vf); the solid line in the figure represents the characteristic curve of the blue light emitting diode, and the broken line represents the characteristic curve of the red light emitting diode. When the junction temperature is raised from 20 ° C to 80 ° C, the light output power of the blue light emitting diode is reduced by about 12%, that is, its hot/cold factor is about 0.88; for the red light emitting diode The light output power of the body is reduced by about 37%, that is, its thermal cooling coefficient is about 0.63. In addition, in terms of wavelength shift, the blue light is not much different from the red light emitting diode, and only slightly changes with the change of Tj; in the change of the forward voltage, when Tj is raised from 20 ° C to 80 ° C The blue light and the red light emitting diode each fall by about 7 to 8%, that is, under constant current operation, the equivalent resistance of the blue light and the red light emitting diode decreases by about 7 to 8%. In summary, since the photoelectric characteristics of the red and blue light-emitting diodes are different in temperature dependence, a problem of a change in the ratio of the red/blue light output power from the initial stage of operation to the steady state occurs. When the illuminating device is composed of red and blue light emitting diodes, the warm white light illuminating device is applied in the field of illumination, and the lighting system is initially illuminated due to the different thermal cooling coefficients of the red light and the blue light emitting diode. As for the timing, the color of the light is unstable, causing inconvenience in use.

Accordingly, the present invention is directed to a light emitting device.

The illuminating device comprises: a first illuminating diode group; a second illuminating diode group connected in parallel to the first illuminating diode group; and a temperature compensating element connected in series to the second illuminating diode a body group; and a first switching element connected between the second group of light emitting diodes and the temperature compensating element.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

200, 400, 600, 601, 602, 800, 900‧‧‧ illuminating devices

202, 502, 802‧‧‧ first light-emitting diode group

204, 503, 804‧‧‧Second light-emitting diode group

206, 405, 506, 605‧‧‧ thermistor

208, 408, 507, 508, 808, 810, 902, 904, 906 ‧ ‧ light emitting diode unit

206‧‧‧First resistance

207‧‧‧second resistance

201‧‧‧First machine component

402, 700‧‧‧Lighting diode group

501‧‧‧ Carrier Board

504‧‧‧3rd LED group

509‧‧‧electrode

510‧‧‧First LED Module

511‧‧‧Voltage modulation device

520‧‧‧Second light-emitting diode module

607, 608‧‧‧Switching elements

609‧‧‧resistance

711‧‧‧ Ditch

720‧‧‧n type contact layer

730‧‧‧n type binding layer

740‧‧‧Active layer

750‧‧‧p type binding layer

760‧‧‧p type contact layer

770‧‧‧Connecting wires

780‧‧‧Insulation

82, 82', 82", 92‧‧‧ temperature compensation components

821‧‧‧Resistance components

8211, 923‧‧‧ resistance

8212, 921‧‧‧ shape memory alloy

830‧‧‧Switch circuit

831‧‧‧ Temperature detection circuit

832‧‧‧Temperature sensing unit

840‧‧‧ Current detection circuit

841‧‧‧current detection unit

9211‧‧‧Contacts

922‧‧‧conductive spring

Figure 1 is a graph showing the effect of junction temperature on the photoelectric characteristics of a light-emitting device.

Fig. 2A is a schematic view showing a light-emitting device in the first embodiment of the present invention.

2B is a schematic view of a light-emitting device in a second embodiment of the present invention.

Figure 3 is a schematic view of a light-emitting device in a third embodiment of the present invention.

Figure 4 is a schematic view of a light-emitting device in a fourth embodiment of the present invention.

Figure 5 is a schematic view of a light-emitting device in a fifth embodiment of the present invention.

Figure 6 is a schematic view of a light-emitting device in a sixth embodiment of the present invention.

6A is a schematic view of a light emitting device according to another embodiment of the present invention.

Figure 6B is a schematic view of a light emitting device in another embodiment of the present invention.

FIG. 7 is a schematic structural view of a group of light emitting diodes of the light emitting device in the above embodiment.

Figure 8 is a schematic view showing the structure of a light-emitting device in a fifth embodiment or a sixth embodiment of the present invention.

Figure 9 is a schematic view of a light-emitting device in a seventh embodiment of the present invention.

10A to 10D are schematic views showing the operation of the light-emitting device at different temperatures in the seventh embodiment of the present invention.

11A to 11D are schematic views of a light-emitting device in an eighth embodiment of the present invention.

12A and 12B are schematic views of a light-emitting device according to a nine embodiment of the present invention.

Figure 13 is a schematic view of a light-emitting device in a tenth embodiment of the present invention.

Figure 14 is a schematic view showing a light-emitting device in an eleventh embodiment of the invention.

The present invention will be described with reference to the drawings, in which the same or the same reference numerals are used in the drawings or the description, and in the drawings, the shape or thickness of the elements may be enlarged or reduced. It is to be noted that elements not shown or described in the figures may be in a form known to those skilled in the art.

2A is a circuit diagram showing a first embodiment of a light-emitting device of the present invention. The light-emitting device 200 includes a first light-emitting diode group 202, a second light-emitting diode group 204, and a temperature compensation component. The temperature compensating element includes a first resistor, such as a thermistor 206 having a positive temperature coefficient. The first LED group 202 includes a first number of LED units 208 connected in series with each other, and the second LED group 204 includes a second number of LED units 208 connected in series with each other. The first light emitting diode group 202 and the second light emitting diode group 204 are electrically connected in series; wherein, the first light emitting diode group 202 and the second light emitting diode group 204 are light emitting diodes The body unit 208 has a thermal cooling coefficient of not more than 0.9, or preferably not more than 0.85, or more preferably not more than 0.8, and includes a light-emitting diode that emits a wavelength range in the visible or invisible range, for example, including red light. Light-emitting diodes in the wavelength range of blue light or ultraviolet light, or light-emitting diodes mainly composed of AlGaInP series materials or GaN series materials. The coefficient of thermal cooling refers to the light transmission of the light-emitting diode at a first temperature (for example, T=80 ° C). The ratio of the output power to the light output power of the light-emitting diode at a second temperature (eg, T=20 ° C). The second temperature is less than the first temperature. The optical output power was standardized and the light output power of the light-emitting diode at T = 20 ° C was set to 100 (or 1).

In this embodiment, the second LED group 204 and the thermistor 206 are electrically connected in parallel, and the first LED group 202 has an equivalent built-in resistance value R ₁ , and the second LED 2 The polar body group 204 has an equivalent built-in resistance value R ₂ , and the thermistor 206 has a resistance value R _PTC , wherein R ₁ and R ₂ decrease approximately as the temperature rises. As shown in FIG. 1, when the light-emitting diode unit 208 is a red or blue light-emitting diode, and T is raised from 20 ° C to 80 ° C, R ₁ and R ₂ are each reduced by about 7 to 8%. The resistance value R _PTC of the thermistor 206 having a positive temperature coefficient has a relationship with temperature, that is, when the temperature rises, the R _PTC rises in a linear or nonlinear relationship. During operation of the illumination device 200, a current I ₁ between about 20 and 1000 milliamps (mA) flows through the first group of light emitting diodes 202 and is shunted through the second group of light emitting diodes. 204 current I ₂ and the current I flowing through the thermistor 206 to _3, wherein _{I 1 = I 2 + I 3} . In addition, the potential difference between the two ends of the second LED group 204 is equal to the potential difference between the two ends of the thermistor 206, that is, I ₃ *R _PTC =I ₂ *R ₂ , therefore, the flow can be known from the above two relations. The current I2 through the second illuminating diode group 204 is approximately positively correlated with R _PTC /(R ₂ +R _PTC ), that is, I ₂ is positively correlated with R _PTC and negatively correlated with R ₂ . In this embodiment, the temperature of the light-emitting device 200 rises during operation. For example, when the temperature rises from the initial operating temperature (second temperature) of 20 ° C to the predetermined temperature (first temperature) of 80 ° C, the resistance value R _PTC of the thermistor 206 rises due to the temperature rise, and The resistance value R ₂ of the second light-emitting diode group 204 decreases as the temperature rises. Therefore, in the case where the fixed current (I ₁ is a fixed value), the second light-emitting diode group 204 is passed. The current I _{2 is} thus increased, and the light output power of the second light emitting diode group 204 also increases as I ₂ increases. In other words, the optical output power of the second illuminating diode group 204 can be controlled by the R _PTC to reduce the attenuation of the optical output power of the second illuminating diode group 204 due to the increase of the thermal cooling coefficient thereof. , to achieve the function of temperature compensation. In addition, by adjusting the number of the light-emitting diode units of the first and second light-emitting diode groups, or selecting a suitable temperature coefficient thermistor, the heat-cooling coefficient of the light-emitting device can be offset or controlled by the temperature rise. The resulting attenuation of the optical output power. It should be noted that the temperature can be the junction temperature or the ambient temperature, and the junction temperature is equal to the ambient temperature at steady state.

In one embodiment, the first group of light emitting diodes 202 can emit blue light having a wavelength of 450 nm to 490 nm and the second group of light emitting diodes 204 can emit red light having a wavelength of 610 nm to 650 nm. The light emitting diode unit 208 in the first light emitting diode group 202 includes a thermal cooling coefficient greater than 0.85 and the light emitting diode unit 208 in the second light emitting diode group 204 includes a thermal cooling coefficient less than 0.85.

Fig. 2B is a circuit diagram showing a second embodiment of the light-emitting device of the present invention. The first light emitting diode group 202 can emit blue light having a wavelength of 450 nm to 490 nm and the second light emitting diode group 204 can emit red light having a wavelength of 610 nm to 650 nm. The temperature compensating component includes a first resistor 206 and a second resistor 207. In this embodiment, the first resistor 206 is connected in parallel with the second LED group 204. The second resistor 207 is connected in series with the first resistor 206 and connected in parallel with the second LED group 204. In this embodiment, the first resistor 206, such as a thermistor, has a first temperature coefficient of resistance, and the second resistor 207 has a second temperature coefficient of resistance. The absolute value of the first temperature coefficient of resistance is more than ten times greater than the absolute value of the temperature coefficient of the second resistor. In addition, the first temperature coefficient of resistance and the temperature coefficient of the second resistor are both positive values. In one embodiment, the first resistor 206 has a first resistance value and the second resistor 207 has a second resistance value. The first resistance value is less than the second resistance value. According to actual needs, the first resistance value may also be greater than or equal to the second resistance value.

It should be noted that the illumination device 200 has a first color temperature at a first temperature and a second color temperature at a second temperature. The second color temperature is less than the first color temperature. When the brightness of the light emitting device 200 is greater than 800 When the lumen is clear, the difference between the first color temperature and the second color temperature is less than 300K. The first color temperature is greater than the second color temperature. The difference between the first temperature and the second temperature is greater than 20 °C.

As shown in FIG. 3, the thermistor 206 having a positive temperature coefficient disclosed in the third embodiment of the present invention can simultaneously be electrically connected to the first light emitting diode group 202 and the second light emitting diode group 204. Sexual parallel. Therefore, when the temperature of the light-emitting device 300 rises, the current passing through the first light-emitting diode group 202 and the second light-emitting diode group 204 is higher than the initial temperature.

4 is a circuit diagram showing a fourth embodiment of the light-emitting device of the present invention. The light-emitting device 400 includes a light-emitting diode group 402 and a thermistor 405 having a negative temperature coefficient. The light emitting diode group 402 includes a plurality of light emitting diode units 408 connected in series with each other, and the light emitting diode group 402 includes a light emitting diode capable of emitting a wavelength range of visible light or invisible light, for example, including red light and blue light. Or a light-emitting diode in the ultraviolet wavelength range, or a light-emitting diode mainly composed of an A1GaInP series material or a GaN series material.

In this embodiment, the light-emitting diode group 402 and the thermistor 405 are electrically connected in series, and the light-emitting diode group 402 has an equivalent built-in resistance value R ₁ , and the thermistor 406 has a resistance value. R _NTC ; where R ₁ decreases approximately as the temperature rises. As shown in FIG. 1, when the light-emitting diode unit 408 is a red or blue light-emitting diode, T rises from 20 ° C to 80 ° C, and R ₁ decreases by about 7 to 8%. The resistance value R _NTC of the thermistor 405 having a negative temperature coefficient has a relationship with temperature, for example, when the temperature rises, the R _NTC decreases in a linear or nonlinear relationship. When the light-emitting device 400 is operated at a constant voltage, the current I ₁ flowing through the light-emitting diode group 402 is about 20 to 1000 milliamperes at a constant voltage of the input value V _in . According to Ohm's law, the current I _{1 is} inversely proportional to the total resistance of the light-emitting diode group 402 and the thermistor 405, that is, I ₁ =V _in /(R ₁ +R _NTC ). In other words, the current I ₁ through the LED group 402 is negatively correlated with R _NTC and R ₁ . In this embodiment, the temperature of the light-emitting device 400 rises during operation. For example, when the temperature is raised from the initial operating temperature (second temperature) of 20 ° C to a predetermined temperature (first temperature) of 80 ° C, the resistance value R _{NTC of the} thermistor 405 and the light emitting diode group 402 The resistance value R ₁ decreases as the temperature rises as described above, and therefore, I ₁ rises accordingly, so that the light output power of the light-emitting diode group 402 increases as I1 rises. In other words, the optical output power of the LED group 402 can be controlled by R _NTC to reduce the attenuation of the light output power of the LED group 402 due to the increase of the thermal cooling coefficient in temperature, and achieve temperature compensation. The function. In addition, by adjusting the number of light-emitting diode units of the light-emitting diode group 402 and/or selecting a suitable temperature coefficient thermistor, the light-emitting device can also be reduced due to the temperature rise of the heat-cooling coefficient. Light output power attenuation.

Fig. 5 is a circuit diagram showing a fifth embodiment of the light-emitting device 500 of the present invention. The illuminating device 500 includes a first illuminating module 510, a second illuminating module 520 connected in parallel with the first illuminating module 510, and a thermal connection with the second illuminating module 520 and having a positive temperature coefficient. Resistor 506. The first light emitting module 510 includes a first light emitting diode group 502, and the second light emitting module 520 includes a second light emitting diode group 503 and a third light emitting diode group 504. The first light emitting diode group 502 includes a first number of first light emitting diode units 507 connected in series with each other, and the second light emitting diode group 503 includes a second number of second light emitting diodes connected in series with each other. The body unit 508, the third group of light emitting diodes 504 includes a third number of second light emitting diode units 508 connected in series with each other; wherein the thermistor 506 is electrically connected in parallel with the third group of light emitting diodes 504 And electrically connected in series with the second group of light emitting diodes 503. The first light emitting module 510 or the first light emitting diode unit 507 has a thermal cooling coefficient of more than 0.85; the second light emitting module 520 or the second light emitting diode unit 508 has a lower thermal cooling coefficient than the first light emitting module. 510 or first light emitting diode unit 507, for example, having a coefficient of thermal cooling of less than 0.85, or preferably less than 0.8. In this embodiment, the first light-emitting diode unit 507 includes a blue light-emitting diode having a thermal cooling coefficient of about 0.88 and emitting a wavelength of 450 nm to 490 nm; and the second light-emitting diode unit 508 includes a thermal cooling coefficient. A red light emitting diode having a wavelength of 610 nm to 650 nm can be emitted, and is not limited thereto. It can also include other light emitting diodes that emit visible or invisible wavelengths, such as green. Light-emitting diodes in the wavelength range of light, yellow, or ultraviolet light, or light-emitting diodes mainly composed of AlGaInP series materials or GaN series materials.

In this embodiment, the third light-emitting diode group 504 and the thermistor 506 are electrically connected in parallel, and the second light-emitting diode group 503 has an equivalent built-in resistance value R ₁ and a third light-emitting diode. The polar body group 504 has an equivalent built-in resistance value R ₂ , and the thermistor 506 has a resistance value R _PTC , wherein R ₁ and R ₂ decrease approximately as the temperature rises. As shown in FIG. 1 , when the second light emitting diode unit is a red or blue light emitting diode, R ₁ and R ₂ are each reduced by about 7 to 8%; and the thermistor 506 having a positive temperature coefficient is The resistance value R _PTC has a relationship with temperature, for example, when the temperature rises, the R _PTC rises in a linear or nonlinear relationship. During operation of the light emitting device 500, a current I ₀ flowing through the first split light emitting module ₁ and I 510 flowing through the second light-emitting module I 520 _2. When passing through the third light emitting diode group 504 of the second light emitting module 520 and the thermistor 506, the I _{2 is} divided into I ₃ flowing through the third light emitting diode group 504 and flowing through the thermistor 506. I ₄ , wherein I ₂ =I ₃ +I ₄ . Moreover, the potential difference between the two ends of the third LED group 504 is equal to the potential difference between the two ends of the thermistor 506, that is, I ₄ *R _PTC =I ₃ *R ₂ . Therefore, it can be known from the above two relations that the current I ₃ flowing through the third light-emitting diode group 504 is positively correlated with R _PTC /(R ₂ +R _PTC ), that is, I ₃ is positively correlated with R _PTC , respectively. And negatively correlated with R ₂ . In this embodiment, during operation, the temperature of the light-emitting device 500 may rise, for example, when the temperature is raised from the initial operating temperature (second temperature) of 20 ° C to a predetermined temperature (first temperature) of 80 ° C. The resistance value R _PTC of the varistor 506 rises as the temperature rises, and the resistance value R2 of the third illuminating diode group 504 decreases as the temperature rises. Therefore, I ₃ rises as the temperature rises, so that the third group of light-emitting diode 504 of the optical output power is increased with increase in I _3. In this embodiment, since the heat-cooling coefficient of the first light-emitting module 510 is larger than that of the second light-emitting module 520, the light output power of the second light-emitting module 520 decreases with temperature and is greater than that of the first light-emitting module. 510, the mixed light color emitted by the first light emitting module 510 and the second light emitting module 520 is shifted toward the light color of the first light emitting module 510 as the temperature rises. However, by controlling the R _{PTC of the} thermistor 506, the light output power of the second light-emitting module 520 can be reduced due to the attenuation of the heat-cooling coefficient when the temperature rises, and the temperature compensation function is achieved. In addition, by adjusting the number of light-emitting diode units of the second and third light-emitting diode groups, or selecting a suitable temperature coefficient thermistor, the second light-emitting module can also be offset or controlled by the heat-cooling The coefficient is attenuated by the light output power caused by the temperature rise. Furthermore, the thermistor 506 disclosed in this embodiment can be electrically connected in parallel with the second LED group 503 and the third LED group 504. Therefore, when the temperature of the illumination device increases. The current passing through the second light emitting diode group 503 and the third light emitting diode group 504 is higher than the initial temperature.

A light-emitting device 600 according to a sixth embodiment of the present invention is shown in Fig. 6. The difference between the sixth embodiment and the fifth embodiment is that the second lighting module 520 is connected in series with a thermistor 605 having a negative temperature coefficient, and the invention is achieved based on the fourth embodiment and the fifth embodiment. Temperature compensation function. In addition, the first light emitting module and the second light emitting module of the fifth and sixth embodiments are not limited to being connected in parallel, and may be respectively connected to an independently controlled current source or voltage source, and still belong to one part of the present invention. Share.

Fig. 6A is a circuit diagram showing another embodiment of the light-emitting device 601 of the present invention. The illuminating device 601 includes a first illuminating module 510, a second illuminating module 520, a thermistor 605 (temperature compensating element), and a switching element 607. In this embodiment, the first light emitting module 510 includes a first light emitting diode group 502, and the second light emitting module 520 includes a second light emitting diode group 504. The first light emitting diode unit 502 can emit blue light having a wavelength of 450 nm to 490 nm; and the second light emitting diode unit can emit red light having a wavelength of 610 nm to 650 nm. The thermal expansion coefficient of the second lighting module 520 is smaller than the thermal cooling coefficient of the first lighting module 510. In other words, the temperature coefficient of the second lighting module 520 is greater than the temperature coefficient of the first lighting module 510 (the light output efficiency of the second lighting module 520 is greater than the first lighting module 510 by the temperature). The first lighting module 510 is connected in parallel with the second lighting module 520. The second lighting module 520 is connected in series to the thermistor 605. The thermistor 605 is a resistor (R_NTC) having a negative temperature coefficient. The switching element 607 is electrically connected between the second lighting module 520 and the thermistor 605. In this embodiment, the switching element 607 is a bi-carrier junction transistor (BJT), and therefore, the current (I _C ) flowing through the second group of LEDs 504 is substantially equal to flowing through the thermistor 605. Current (I _E ). In detail, the dual-carrier junction transistor has three nodes: emitter (node E), collector (node C), and base (base B). Node C is connected to second light emitting diode group 504 and node E is connected to thermistor 605. A voltage modulation device 511 is connected between the node M and the node N. The voltage at node M is equal to the voltage at node B. It should be noted that the voltage (V _MN ) applied between the node M and the node N of the voltage modulation device 511 is equal to the voltage (V _BN ) between the node B and the node N. The voltage (V _BN ) between the node B and the node N includes the junction voltage (V _BE ) between the node B and the node E and the voltage across the thermistor 605 (V _{R — NTC} ). Therefore, V _MN =V _BE +V _{R_NTC} . For example, the voltage modulation device 511 includes a diode of two germanium materials, so V _MN = 1.4V, and when the bipolar junction transistor is a germanium transistor, the junction voltage V _BE = 0.7V; V _{R_NTC} = 1.4V - 0.7V = 0.7V. According to Ohm's law V _{R_NTC} =I _E *R _{_} NTC, the current I _E can be adjusted or determined by V _{R_NTC} and R_NTC. Similarly, because I _C ≒I _E , the current (I _C ) flowing through the second illuminating diode group 504 can also be determined by _{VR_NTC} and R_NTC. In another embodiment, the switching element 607 can include a power bipolar junction transistor, a bipolar junction transistor, a heterojunction bipolar transistor, a metal-oxide-semiconductor field effect transistor, a power metal. An oxide-semiconductor field effect transistor, a high electron mobility transistor (HEMT), a controlled voltage rectifier (SCR), an insulated gate bipolar transistor (IGBT), or a combination thereof.

Referring to Figure 6A, for example, the illumination device 601 operates at a certain voltage. During operation of the illuminating device 601 at a temperature of 20 ° C, the current I ₁ (20 ° C) flowing through the first illuminating diode group 502 is at a fixed input voltage V _in about 20 to 1000 milliamperes (mA), and flows through The current I _{C (20 ° C) of the} second light-emitting diode group 504 and the thermistor 605 (≒I _{E (20 ° C)} ) is about 20 to 1000 milliamperes (mA) at a fixed input voltage V _in . Since the second LED group 504 is connected in series with the switching element 607 and the thermistor 605, the fixed input voltage V _in is the forward voltage (V _LED ), the node C and the node of the second LED group 504. The sum of the voltage of E (V _CE ) and the voltage of the thermistor 605 (V _{R — NTC} ), that is, V _in =V _LED +V _CE +V _{R_NTC} .

It is worth noting that since the thermistor 605 is a resistor (R _{_} NTC) having a negative temperature coefficient, the resistance value R _{NTC of the} thermistor decreases as the temperature rises. Although the voltage of the voltage modulation device 511 also decreases as the temperature rises, the variability is much smaller than the thermistor 605. Therefore, at a temperature of 80 ° C, the net current flowing through the thermistor 605 is increased, that is, the current flowing through the thermistor 605 is larger at a temperature of 80 ° C than at a temperature of 20 ° C. Moreover, since the current (I _C ) flowing through the second group of light-emitting diodes 504 is substantially equal to the current (I _E ), the current (I _C ) also increases, that is, flows through the second light-emitting diode. The current of group 504 is greater at a temperature of 80 ° C than at a temperature of 20 ° C. Thereby, the light output power of the second light-emitting diode group 504 can be slowed down due to the smaller heat-cooling coefficient (or a larger temperature coefficient) when the temperature rises, thereby enabling the second light-emitting second The relative steady state ratio between the red light output power of the polar body group 504 and the blue light output power of the first light emitting diode group 502 can be maintained at a certain temperature at different temperatures. Therefore, the light-emitting device 601 still has a stable color temperature at different temperatures.

In the present embodiment, the function of switching element 607 is to regulate the current flowing through second light emitting diode group 504 during operation. That is, when the voltage deviates from a predetermined range, the current can still be controlled to a predetermined range. Specifically, during the manufacturing process, the forward voltage (V _LED ) of the second LED group 504 may deviate from a predetermined value. However, due to the presence of the switching element 607, an off voltage can be applied to the switching element 607. Therefore, it is not necessary to individually adjust the thermistor 605 due to the difference in forward voltage between the groups of light-emitting diodes (for example, two groups of light-emitting diodes having different forward voltages can be individually connected to the same heat. The varistor), and the switching current flowing through the group of illuminating diodes can be maintained at the same current value by the switching element 607. In addition, when the temperature rises from 20 ° C to 80 ° C, because the forward voltage (V _LED ) of the second light emitting diode group 504 is lowered, the additional voltage variation of the second light emitting diode group 504 (ΔV = The V _LED (20 ° C) - V _LED (80 ° C) can also be applied to the switching element 607 without affecting the voltage across the thermistor 605. Further, because of this circuit configuration, the current (I _C ) flowing through the second LED group 504 is mainly determined by the voltage modulation device 511. Therefore, the current is varied at different temperatures by the switching element 607. It can still be kept at a predetermined value. Fig. 6B is a circuit diagram showing another embodiment of the light-emitting device 602 of the present invention. Light emitting device 602 has a circuit diagram similar to light emitting device 601. A switching element 608 and a resistor 609 are electrically connected to the first LED group 502. Switching element 608 is placed between first light emitting diode group 502 and resistor 609. Similarly, due to this circuit configuration, the current flowing through the first group of light emitting diodes 502 and the current flowing through the second group of light emitting diodes 504 are primarily determined by the voltage modulation device 511. In addition, by the switching element 608, when the forward voltage (V _LED ) of the first light emitting diode group 502 decreases as the temperature rises, the additional voltage variation of the forward voltage of the first light emitting diode group 502 (ΔV = V _LED (20 ° C) - V _LED (80 ° C)) can also be applied to the switching element 608, and the current is still maintained at a predetermined value. The switching element 608 comprises a power bipolar junction transistor, a bipolar junction transistor, a heterojunction bipolar transistor, a metal-oxide-semiconductor field effect transistor, a power metal-oxide-semiconductor field effect A transistor, a high electron mobility transistor (HEMT), a controlled voltage rectifier (SCR), an insulated gate bipolar transistor (IGBT), or a combination thereof. The thermistor 605 has a first temperature coefficient of resistance and the resistor 609 has a second temperature coefficient of resistance; the absolute value of the temperature coefficient of the first resistor is more than ten times greater than the absolute value of the temperature coefficient of the second resistor.

FIG. 7 is a schematic view showing the structure of a group of light-emitting diodes disclosed in the foregoing embodiments of the present invention. The light emitting diode group 700 includes a substrate 710 and a plurality of light emitting diode units collectively grown or bonded to the substrate 710 in an array and separated by a trench 711. Each of the plurality of light emitting diode units includes an n-type contact layer 720 formed on the substrate 710, an n-type cladding layer 730 formed on the contact layer 720, and an active layer 740 formed on the active layer 740. Above the n-type tie layer 730, a p-type tie layer 750 is formed on the active layer 740, a p-type contact layer 760 is formed on the p-type tie layer 750, and a connecting wire 770 is electrically connected to each of the light-emitting diodes. The n-type contact layer 720 of the cell to the p-type contact layer 760 of the other light-emitting diode unit to form a series structure, and an insulating layer 780 is formed between the trench 711 and the connecting wire 770 to prevent unavoidable short circuit path. The n-type tie layer 730 and the p-type tie layer 750 respectively provide electrons and holes, and electrons and holes are combined in the active layer 740 to emit light. The contact layer provides an ohmic contact interface between an electrode and the tie layer. In one embodiment of the present invention, the LED group 700 includes a plurality of LED arrays that are formed on a single substrate, such as a blue high voltage array that emits blue light and operates at a voltage of 60 to 120V. A wafer or a red light high voltage array single chip that emits red light and operates at a voltage of 30 to 50V. The operating voltage depends on the number of light-emitting diode units connected in series. Wherein the material of the n-type or p-type contact layer, the n-type or p-type tie layer, or the active layer comprises a group III-V compound, for example, comprising Al _x In _y Ga _(1-xy) N or Al _x In _y Ga _(1-xy) P, where 0 ≦ x, y ≦ 1; (x + y) ≦ 1.

8 is a schematic structural view of a fifth or sixth embodiment of a light-emitting device according to the present invention, wherein the first light-emitting module 510 of the light-emitting device 500 or 600 includes a blue high-voltage array single wafer as disclosed in FIG. 7, and a second light-emitting device. The module 520 includes a red light high voltage array single chip electrically connected to a thermistor 506 or 605 as shown in FIG. 7; the two electrodes 509 are electrically connected to the first light emitting module 510 and the second light emitting module. The 520 is used to receive a power signal. The first lighting module 510, the second lighting module 520, the temperature compensating component (thermistor 506, 605), and the electrode 509 are formed on a carrier 501.

Fig. 9 is a circuit diagram showing a seventh embodiment of the light-emitting device 800 of the present invention. The illuminating device 800 includes a first illuminating diode group 802 and a second illuminating diode group 804. The first light emitting diode group 802 includes a first number of first light emitting diode units 808 connected in series with each other, and the second light emitting diode group 804 includes a second number of second light emitting diodes connected in series with each other. The body unit 810, the first light emitting diode group 802 and the second light emitting diode group 804 are connected to each other in series. The light emitting diode unit 808, 810 includes a light emitting diode that emits a wavelength range of visible light or invisible light, such as a light emitting diode including a red, blue, or ultraviolet wavelength range, or an AlGaInP series material or GaN. A series of light-emitting diodes. In this embodiment, the first light emitting diode group 802 can emit blue light having a wavelength of 450 nm to 490 nm and the second light emitting diode group 804 can emit red light having a wavelength of 610 nm to 650 nm. The illuminating device 800 further includes a temperature compensating element 82 connected in parallel to the second illuminating diode group 804. The temperature compensating element 82 can be in an electronically operated form or in a mechanically operated form. In the present embodiment, temperature compensating element 82 is in a mechanically operated form and includes a plurality of resistive components 821. Each resistor assembly 821 includes a resistor 8211 and a mechanical switch 8212. The switch 8212 includes a microactuator, a one-way or two way-shaped memory alloy, a bi-metallic strip, or a capillary thermostat switch. The resistors 8211 in each of the resistor components 821 have the same resistance value. In another embodiment, the resistor 8211 in each resistor assembly 821 can have different resistance values depending on actual needs. The number of resistor components 821 can also vary. The switch can be controlled to be connected or connected to the temperature depending on the design.

In the present embodiment, the switch 8212 is a bidirectional shape memory alloy, and the shape of the shape memory alloy can be deformed as the temperature changes. In a first stage, referring to FIG. 10A, during operation of the light-emitting device 800 at 20 ° C, the shape memory alloy 8212 is connected to the resistor 8211 so that the resistor 8211 (in the present embodiment, three resistors as an example) is connected in parallel to A second light emitting diode group 804. Therefore, the current I ₁₁ flowing through the first light-emitting diode group 802 of 20 to 1000 milliamperes is divided into a current I ₂₁ flowing through the second light-emitting diode group 804 and a current I flowing through the temperature compensating element 82. ₃₁ ; wherein, I ₁₁ = I ₂₁ + I ₃₁ . In a second stage, referring to FIG. 10B, the temperature is 40 ° C, wherein the shape of a shape memory alloy 8212 is deformed such that one resistor 8211 is not connected to the second group of light emitting diodes 804, and thus the total resistance of the resistor assembly 821. The increase (i.e., the resistance of the temperature compensating element increases) and the current I ₃₂ (<I ₃₁ ) flowing through the temperature compensating element 82 become smaller. Because the current I ₁₂ (=I ₁₁ =I ₂₂ +I ₃₂ ) flowing through the first group of light emitting diodes 802 is fixed, when the resistance of the temperature compensating element 82 increases, flowing through the second group of light emitting diodes The current I ₂₂ (>I ₂₁ ) of 804 is thus increased. Similarly, in a third stage, referring to FIG. 10C, the temperature is 60 ° C, and the shape of the other shape memory alloy 8212 is also deformed such that the two resistors 8211 are not connected to the first light-emitting diode group 804, and thus the phase Compared to Fig. 10B, the total resistance of the resistor block 821 is increased (i.e., the resistance of the temperature compensating element is also increased), and the current I ₃₃ (<I ₃₂ ) flowing through the temperature compensating element 82 becomes small. The current I ₂₃ (>I ₂₂ ) flowing through the second group of light emitting diodes 804 thus increases. In a fourth stage, referring to FIG. 10D, the temperature is 80 ° C, and the shapes of the three shape memory alloys 8212 are deformed such that all the resistors 8211 are not connected to the second group of light emitting diodes 804, thus flowing through the first light. The current I ₁₄ (=I ₁₁ =I ₁₂ =I ₁₃ ) of the diode group 802 is not shunted and this current also flows through the second illuminating diode group 804 (I ₂₄ >I ₂₃ ). By breaking the connection between the resistor component 821 and the second LED group 804, the total resistance of the resistor component 821 is increased (ie, the resistance of the temperature compensating component is increased), and when flowing through the temperature compensating component 82 and When the current flowing through the second group of light emitting diodes 804 is a fixed value, the increase in the total resistance of the resistor assembly 821 causes the current flowing through the temperature compensating element 82 to decrease and the current flowing through the second group of light emitting diodes 804. increase. Therefore, the resistance of the temperature compensating element can be controlled to reduce the attenuation of the optical output power of the second illuminating diode group 804 due to the increase in the thermal cooling coefficient thereof, thereby achieving the function of temperature compensation. It should be noted that when the resistance value of each resistance component is the same, the first difference of the resistance values between the first phase and the second phase is smaller than the second difference between the resistance values of the second phase and the third phase. The second difference is less than the third difference in resistance between the third and fourth stages. In an embodiment, the resistance value of each resistor component can be different.

11A to 11C are circuit diagrams showing an eighth embodiment of the light-emitting device of the present invention. As shown in FIG. 11A, the temperature compensating element 82' is connected in parallel to the second light emitting diode group 804. The temperature compensating element 82' includes a first resistor 8214 having a first resistance value, a second resistor 8215 having a second resistance value, and a switch 8212. The second resistance value is less than the first resistance value. The first resistance value is at least two times greater than the second resistance value. The switch 8212 is a shape memory alloy. During operation at 20 ° C, as shown in FIG. 11B, the switch 8212 is connected to the second resistor 8215 and is not connected to the first resistor 8214. Current I ₁₅ flowing through first light-emitting diode group 802 is shunted into current I ₂₅ flowing through second light-emitting diode group 804 and current I ₃₅ flowing through second resistor 8215; wherein, I ₁₅ = I ₂₅ +I ₃₅ . At a temperature of 50 ° C, as shown in FIG. 11C, the shape of the switch 8212 changes to thereby disconnect the second resistor 8215 and is connected to the first resistor 8214, the resistance of the first resistor being greater than the resistance of the second resistor. Since the current I ₁₆ (=I ₁₅ =I ₂₆ +I ₃₆ ) flowing through the first light-emitting diode group 802 is fixed, when the resistance of the temperature compensating element 82' increases, the current flowing through the temperature compensating element 82' I ₃₆ (<I ₃₅ ) is reduced, thereby increasing the current I ₂₆ (>I ₂₅ ) flowing through the second group of light emitting diodes 804. At a temperature of 80 ° C, as shown in FIG. 11D, the shape of the switch 8212 changes and is not connected to the first resistor 8214 and the second resistor 8215, whereby the current I17 flowing through the first LED group 802 It is not shunted and this current also flows through the second illuminating diode group 804 (I ₂₇ >I ₂₆ ). Therefore, the resistance of the temperature compensating element 82' can be controlled to reduce the attenuation of the light output power of the second light emitting diode group 804 due to the increase in the thermal cooling coefficient thereof, thereby achieving the function of temperature compensation.

12A and 12B are circuit diagrams showing a ninth embodiment of the light-emitting device of the present invention. As shown in FIG. 12A, the temperature compensating element 92 includes a one-way shape memory alloy 921, a conductive spring 922, and a resistor 923. At a temperature of 20 ° C, the shape memory alloy 921 has an end point fixed to one end of the conductive spring 922, and the end of the shape memory alloy 921 is connected to the second light emitting diode group 804 at a joint 9211. The conductive spring 922 has another end connected to the resistor 923, so the resistor 923 is connected in parallel with the second LED group 804. Current I ₁₈ flowing through first light-emitting diode group 802 is shunted by current I28 flowing through second light-emitting diode group 804 and current I ₃₈ flowing through resistor 923. At a temperature of 80 ° C (or 40 ° C or 60 ° C), the shape memory alloy 921 changes shape and is pressurized to the conductive spring 922, thereby breaking the connection between the conductive spring 922 and the resistor 923 as shown in FIG. 12B. Therefore, the current I ₁₉ flowing through the first group of light emitting diodes 802 is not shunted and this current also flows through the second group of light emitting diodes 804. Then, when the temperature is lowered from 80 ° C to 20 ° C, the restoring force existing in the conductive spring 922 is released and the shape memory alloy 921 is forced to be connected to the second light emitting diode group 804, thus again making the resistance The 923 is connected in parallel with the second light emitting diode group 804.

Figure 13 is a circuit diagram showing a tenth embodiment of the light-emitting device of the present invention. The temperature compensating element 82" is an electronically operated form and includes a temperature sensing unit 832, a temperature detecting circuit 831, a switching circuit 830, and a plurality of resistors 834. The switching circuit 830 includes a bi-carrier junction transistor, power Double carrier junction transistor, heterojunction bipolar transistor, metal-oxide-semiconductor field effect transistor, power metal-oxide-semiconductor field effect transistor, high electron mobility transistor (HEMT), A temperature controlled circuit 831 and a switch circuit 830 can be integrated into an integrated circuit. In operation, the temperature sensing unit 832 senses a first control circuit (SCR), an insulated gate bipolar transistor (IGBT), or a combination thereof. The temperature is transmitted to the temperature detecting circuit 831. Thereafter, the temperature detecting circuit 831 controls the switching circuit 830 based on the signal from the temperature sensing unit 832 such that the resistor 834 is connected or not connected to the second light emitting diode group 804. Similarly, in the seventh embodiment of the 9th to 10th drawings, at a temperature of 20 ° C, all the resistors 834 are connected in parallel with the second group of LEDs 804. At a temperature of 40 ° C, one of the resistors is not the second Light-emitting diode group 8 04. At a temperature of 60 ° C, the two resistors are not connected to the second group of light emitting diodes 804. At a temperature of 80 ° C, all of the resistors are not connected to the second group of light emitting diodes 804.

Fig. 14 is a circuit diagram showing the eleventh embodiment of the light-emitting device 900 of the present invention. The illuminating device 900 includes a first illuminating diode group 902 and a second illuminating diode group 904. The first light emitting diode group 902 includes a first number of light emitting diode units 908 connected in series with each other, and the second light emitting diode group 904 includes a second number of light emitting diode units 908 connected in series with each other. The first light emitting diode group 902 and the second light emitting diode group 904 are electrically connected in series. The light-emitting device 900 has a structure similar to that of the light-emitting device of the tenth embodiment. The light emitting device 900 further includes a light emitting diode unit 906 and a second light emitting diode group 904 electrically connected in parallel. The light emitting diode unit 906, 908, 910 includes a light emitting diode capable of emitting a wavelength range of visible light or invisible light, for example, a light emitting diode including a red, blue, or ultraviolet wavelength range, or an AlGaInP series material. Or a GaN series material-based light-emitting diode. The illuminating device 900 includes a temperature compensating component 82", a current detecting unit 841 and a current detecting circuit 840. The current detecting unit detects the current flowing through the second illuminating diode group 904 and transmits a signal to the current Detector. The circuit 840 is tested. The current detecting circuit 840 then controls whether the light emitting diode unit 906 emits light based on the current signal from the current detecting unit 841. In this embodiment, the light emitting diode units 906, 910 emit red light and The light emitting diode unit 908 emits blue light. When the current is less than 3 mA, the light output efficiency of the red light emitting diode is attenuated more than the light output efficiency of the blue light emitting diode. Therefore, when the current detecting unit 841 detects When the current flowing through the second light emitting diode group 904 is less than 3 mA, the signal from the current detecting unit 841 is transmitted to the current detecting circuit 840 to control and cause the light emitting diode unit 906 to emit light. The temperature compensation component 82" current detecting circuit 840 can be integrated into an integrated circuit.

It is to be understood that the above-described embodiments of the present invention may be combined or substituted with each other as appropriate, and are not limited to the specific embodiments described. The examples of the invention are intended to be illustrative only and not to limit the scope of the invention. Any obvious modifications or variations of the present invention are possible without departing from the spirit and scope of the invention.

601‧‧‧Lighting device

502‧‧‧First LED group

504‧‧‧Second Light Diode Group

510‧‧‧First lighting module

511‧‧‧Voltage modulation device

520‧‧‧Second lighting module

605‧‧‧Thermistor

607‧‧‧Switching elements

Claims (10)

An illuminating device includes: a first illuminating diode group having a first thermal cooling coefficient, including a first end point, a second end point, and a plurality of first illuminating diodes connected in series with each other a second light emitting diode group having a second thermal cooling coefficient greater than the first thermal cooling coefficient and electrically connected in series with the first light emitting diode group; a temperature compensating element does not include a diode element and is electrically connected in parallel with the first end point and the second end point and the first light emitting diode group, and has a first resistor and a first series connected in series a second resistor, wherein the first resistor has a first temperature coefficient, and the second resistor has a second temperature coefficient; an absolute value of the first temperature coefficient is more than ten times greater than an absolute value of the second temperature coefficient; The first light emitting diode group and the second light emitting diode group simultaneously emit light of different colors. The illuminating device of claim 1, wherein the first temperature coefficient is positive. The illuminating device of claim 1, wherein the second temperature coefficient is positive. The illuminating device of claim 1, wherein the first illuminating diode group comprises a illuminating diode emitting red light. The illuminating device of claim 1, wherein the second illuminating diode group comprises a plurality of second illuminating diode units connected in series. The illuminating device of claim 5, wherein the second illuminating diode group comprises a blue light emitting diode. The illuminating device of claim 1, further comprising a carrier, wherein the first illuminating diode group, the second illuminating diode group and the temperature compensating component are formed on the carrier . The illuminating device of claim 1, wherein the temperature compensating element has a resistance value, the resistance value being higher than the resistance value at a second temperature at a first temperature, the second temperature ratio being The first temperature is low. An illuminating device includes: a first illuminating diode group including a first end point, a second end point, and a plurality of first illuminating diode units connected in series; a second illuminating diode The body group and the first light emitting diode group are electrically connected in series at the second end point, and include a plurality of second light emitting diode units connected in series; and a temperature compensating element does not include the diode The first electrical terminal and the second terminal are electrically connected in parallel with the first light emitting diode group, and have a first resistor and a second resistor connected in series with each other; wherein the first resistor has a first temperature coefficient, the second resistor has a second temperature coefficient; an absolute value of the first temperature coefficient is more than ten times greater than an absolute value of the second temperature coefficient; wherein the first light emitting diode group and The second light emitting diode group simultaneously emits light of different colors, wherein the light emitting device has a first color temperature at a first temperature and a second color temperature at a second temperature, the second temperature is greater than the first temperature a low temperature, wherein the first temperature and the second temperature From greater than 20 degrees, and the gap between the first and the second color temperature is the color temperature of less than 300K. The illuminating device of claim 9, wherein the first color temperature is higher than the second color temperature.