CN219180535U

CN219180535U - Light-emitting structure

Info

Publication number: CN219180535U
Application number: CN202223335163.4U
Authority: CN
Inventors: 邢陈震仑; 洪荣豪; 杨詠钧
Original assignee: Prolight Opto Technology Corp
Current assignee: Prolight Opto Technology Corp
Priority date: 2022-12-12
Filing date: 2022-12-12
Publication date: 2023-06-13
Anticipated expiration: 2032-12-12

Abstract

A light-emitting structure comprises a bearing unit, a light-emitting unit and a light-transmitting unit. The light-emitting unit is arranged on the bearing unit and comprises a light-emitting surface. The light transmitting unit directly contacts the light emitting unit and includes a first face and a second face opposite to each other. The first surface is covered on at least part of the light-emitting surface, and the second surface is directly contacted with the gas.

Description

Light-emitting structure

Technical Field

The present utility model relates to a light emitting structure, and more particularly to a light emitting structure capable of enhancing red light output intensity.

Background

A light-emitting diode (LED) is a semiconductor device, and mainly converts electrical energy into light energy through a semiconductor compound to achieve a light-emitting effect, and has advantages of long service life, high stability, and low power consumption, so that the LED is widely used for illumination. With the relative maturity of blue and green chip technologies, the efficiency is continuously improved, and in order to adapt to the application fields of professional illumination (for example, stage theatres, art shows or medical equipment applications, etc.), the output intensity of red light is relatively important in consideration of the requirements of RGB light mixing application and color rendering index (color rendering index, CRI).

The traditional technology is to cover the package with glue material, which can protect the chip and gold wire from being damaged by external force and failure, and can also be used to change the light emitting angle and increase the brightness of the chip.

However, with the advancement of packaging technology, the increase in wattage requirements, the shrinking of packaging volume, and the application of multi-color poly, new packaging types have been developed. Conventional early LED packages, such as plug-in (lamp), PLCC rack, or SMD type, have a glue covering the chip, which is intended to: (1) protecting the chip and gold wire from failure by external force damage; (2) improving the brightness of the chip; (3) changing the light emission angle. However, no matter which package is adopted in the conventional technology, the upper head of the monochromatic light chip is not subjected to any treatment except that the blue light chip and the fluorescent powder are converted into a white light LED. At this time, the LED package brightness (lm ormW) is the brightness of the die itself. Such brightness is generally about 20 to 30% lost depending on the wavelength.

Therefore, how to design a light-emitting structure that can improve brightness without affecting optics to solve the above-mentioned technical problems is an important issue for the present inventor to study.

Disclosure of Invention

One of the objectives of the present utility model is to provide a light emitting structure, which can improve the red light brightness of the brand-new package type, and achieve the purposes of simple structure, easy production and low production cost.

In order to achieve the above-mentioned objective, a light emitting structure according to the present utility model includes a carrier unit, a light emitting unit, and a light transmitting unit. The light-emitting unit is arranged on the bearing unit and comprises a light-emitting surface. The light transmitting unit directly contacts the light emitting unit and includes a first face and a second face opposite to each other. The first surface is covered on at least part of the light-emitting surface, and the second surface is directly contacted with the gas.

In some embodiments, the area of the light-transmitting unit covered on the light-emitting unit is 0.8 to 1.2 times that of the light-emitting surface.

In some embodiments, the light-emitting structure further includes a reflective unit disposed on the carrier unit and surrounding the periphery of the light-emitting unit

In some embodiments, the reflective unit includes a white colloid, and the white colloid is disposed around the periphery of the light-transmitting unit.

In some embodiments, the second face of the light transmissive unit is formed as a planar surface or as a cambered surface along the surface Zhang Lixing.

In some embodiments, the light emitting structure further includes a transparent cover disposed on the carrying unit and covering the light emitting unit and the light transmitting unit.

In some embodiments, the transparent cover comprises at least one vent hole adjacent to the periphery of the carrying unit.

In certain embodiments, the gas comprises an inert gas or an atmosphere.

In some embodiments, the carrier unit comprises a substrate or a leadframe.

In some embodiments, the peak emission wavelength of the light emitting unit is greater than or equal to 600 nanometers, and the refractive index of the light transmitting unit is greater than or equal to 1.3.

In summary, the light emitting structure of the present utility model enables the red light with low energy to be captured and accumulated therein by the light transmitting unit directly contacting with the light emitting unit, and enables the red light output from the light transmitting unit to have a certain light intensity. Furthermore, for the wavelength of the red light with lower energy, compared with the traditional scheme of directly entering the atmosphere, the light transmission unit further provides an optical cavity with lower refractive index variation, so that the loss of the output energy of the red light is avoided, the fluorescent powder or the fluorescent layer is not required to be configured, and the production difficulty and the cost are reduced.

Therefore, the luminous structure disclosed by the utility model can improve the technical problem of the output intensity of red light in a brand-new packaging type, and achieves the purposes of simple structure, easiness in production and low production cost.

It should be noted that, the form of contacting the gas without contacting the encapsulation glue in the light emitting direction of the led may be referred to as "air-type", and this patent value is mainly to use "air-type" as an encapsulation technology to improve the light efficiency (e.g. red light brightening).

The utility model will now be described in more detail with reference to the drawings and specific examples, which are not intended to limit the utility model thereto.

Drawings

Fig. 1A and 1B are schematic cross-sectional views of a light emitting structure according to a first embodiment of the present utility model;

fig. 2 is a schematic cross-sectional view of a light emitting structure according to a second embodiment of the present utility model;

fig. 3 is a schematic cross-sectional view of a light emitting structure according to a third embodiment of the present utility model;

fig. 4 is a schematic top view of a light emitting structure according to a third embodiment of the present utility model;

fig. 5 is a schematic cross-sectional view of a light emitting structure according to a fourth embodiment of the present utility model;

fig. 6 is a schematic cross-sectional view of a light emitting structure according to a fifth embodiment of the present utility model; and

FIG. 7 is a graph showing the relationship between the brightness ratio of the light emitting structure and the thickness of the transparent unit.

Wherein, the reference numerals:

1 to 5: light-emitting structure

10. 10a: bearing unit

20: light-emitting unit

21: light-emitting surface

30: light transmitting unit

31: first surface

32: a second surface

40: transparent cover

41: air vent

50: reflection unit

60: cover plate

100: gas and its preparation method

200: space of

A: experimental values

B: trend line

Detailed Description

The structural and operational principles of the present utility model are described in detail below with reference to the accompanying drawings:

fig. 1A and 1B are schematic cross-sectional views of a light emitting structure 1 according to a first embodiment of the present utility model.

As shown in fig. 1A and 1B, a light emitting structure 1 according to a first embodiment of the present utility model includes a carrying unit 10, a light emitting unit 20, and a light transmitting unit 30.

The carrying unit 10 is used for carrying the light emitting unit 20 and the light transmitting unit 30.

In some embodiments, the carrier unit 10 may comprise aluminum nitride, aluminum oxide, polyethylene terephthalate (positron emissiontomography, PET), bismaleimide triazine resin (bismaleimide triazine, also referred to as BT resin), or ceramic, but is not limited thereto.

In some embodiments, the carrier unit 10 may be a printed circuit board (printed circuitboard, PCB), a ceramic substrate with wiring (ceramic substrate), or a lead frame (leadframe), etc. Further, in the first embodiment shown in fig. 1A, the carrying unit 10 is a plate-shaped substrate (or a bowl-shaped frame form) but is not limited thereto.

The light emitting unit 20 is disposed above the carrying unit 10 and includes a light emitting surface 21.

In some embodiments, the light emitting unit 20 draws power from the carrier unit 10 and emits light, such as by using conductive lines made of aluminum, silver, copper, nickel, palladium, gold, etc., or by using conductive lines made of transparent conductive material (e.g., indium Tin Oxide (ITO), etc.), but not limited thereto.

In some embodiments, the peak emission wavelength (peak emission wavelength, WLP) of the light emitting unit 20 is greater than or equal to 600 nm, especially between 600 nm and 680 nm, i.e. the visual color of the light output by the light emitting unit 20 is red light corresponding to the visible light range, but is not limited thereto.

In some embodiments, the light emitting unit 20 may further include red light emitting diodes (e.g., aluminum gallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP), indium gallium aluminum phosphide (AlGaInP), gallium phosphide doped zinc oxide (GaP: znO)), orange light emitting diodes (e.g., gallium arsenide phosphide (GaAsP), indium gallium aluminum phosphide (AlGaInP), gallium phosphide doped X (GaP: X)), yellow light emitting diodes (e.g., gallium arsenide phosphide (GaAsP), indium gallium aluminum phosphide (AlGaInP), gallium phosphide doped nitrogen (GaP: N)), green light emitting diodes (e.g., indium gallium nitride (InGaN), gallium nitride (GaN), gallium phosphide (GaP), indium gallium aluminum phosphide (AlGaInP), aluminum gallium phosphide (lGaP)), blue light emitting diodes (e.g., zinc selenide (ZnSe), indium gallium nitride (InGaN), silicon carbide (SiC)), violet light emitting diodes (e.g., indium gallium phosphide (InGaN)), infrared light emitting diodes (e.g., gaAs), aluminum gallium arsenide (AlGaInGaN), or aluminum gallium nitride (AlGaInGaN), light emitting diodes (AlGaAlGaAlGaInGaN), light emitting diodes (AlGaAlGaAlInGaN) of the non-visible light range, light emitting diode (AlGaAlGaAlInGaN) may include ultraviolet light emitting diodes, however, it is not limiting.

The light transmitting unit 30 directly contacts the light emitting unit 20, and includes a first face 31 and a second face 32 opposite to each other. Further, the first surface 31 is disposed on at least a portion of the light-emitting surface 21, and the second surface 32 directly contacts the gas 100, which is not contacted by the encapsulant in the light-emitting direction of the led but contacted by the gas 100, which may be referred to as "air-type" structure. Further, the gas 100 may comprise an inert gas or atmosphere, although it is not limited thereto.

In some embodiments, the area of the light-transmitting unit 30 covered on the light-emitting unit 20 is 0.8 to 1.2 times the area of the light-emitting surface 21.

In some embodiments, the second face 32 of the light transmitting unit 30 is formed as a plane or as a cambered surface according to surface tension (surface tension). Further, in the first embodiment shown in fig. 1B, the second surface 32 of the light-transmitting unit 30 is parallel to the light-emitting unit 20 in a parallel plane, but is not limited thereto.

In some embodiments, the refractive index of the light-transmitting unit 30 is greater than or equal to 1.3, and the light-transmitting unit 30 may comprise quartz, glass, ceramic, silica gel, epoxy, or a silica gel-epoxy composition (silicone-epoxy) composed of the above materials, but is not limited thereto.

It should be noted that the light transmitting unit 30 of the present utility model directly contacts the light emitting unit 20 and the gas 100 simultaneously, and the refractive index of the atmosphere is very close to 1 for various frequencies of light, for example, 1.00027 at 20 ℃ and under the atmosphere of 760mmHg, and is about 1.45 to 1.9 relative to the substrate such as quartz, acrylic plate or flint glass. For light transmission, transmission in a state where the refractive index difference is larger causes energy loss of more light intensity. To this end, the present utility model introduces a structure in which the light-transmitting unit 30 is directly disposed on the light-emitting unit 20, and the refractive index of the light-transmitting unit 30 is between the refractive indexes of the light-emitting unit 20 and the gas 100 (e.g., the atmosphere or inert gas), so that the light-emitting surface 21 of the light-emitting unit 20 does not directly contact the gas 100, and the light has minimal refractive index difference and minimal energy loss of light intensity when the light is transmitted from the light-emitting unit 20 to the light-transmitting unit 30 and from the light-transmitting unit 30 to the gas 100, especially for the light with the peak emission Wavelength (WLP) of 600 nm or more outputted by the light-emitting unit 20, the present utility model can enhance the light intensity by 10% to 20% compared with the conventional structure without the light-transmitting unit 30, such as 117%, but is not limited thereto

For this reason, the light emitting structure 1 of the present utility model allows the light transmitting unit 30 in direct contact with the light emitting unit 20 to capture and accumulate the low-energy red light wavelength (e.g. 600 nm or more) therein (i.e. between the first surface 31 and the second surface 32 of the light transmitting unit 30), and allows the red light outputted from the light transmitting unit 30 to have a certain light intensity. Furthermore, for the wavelength of the red light with lower energy, compared with the conventional scheme of directly entering the atmosphere, the light transmitting unit 30 further provides an optical cavity with lower refractive index variation, so as to avoid the loss of the output energy of the red light, and to improve the output intensity of the red light in the brand-new packaging type, thereby achieving the purposes of simple structure, easy production and low production cost.

Fig. 2 is a schematic cross-sectional view of a light emitting structure 2 according to a second embodiment of the present utility model.

Referring to fig. 1A to 2, the light emitting structure 2 according to the second embodiment of the present utility model is substantially the same as the light emitting structure 1 of the first embodiment, but the second surface 32 of the light transmitting unit 30 is formed into a cambered surface according to the surface tension (surface tension), which is not limited.

For this reason, the light emitting structure 2 of the present utility model is formed by the light transmitting unit 30 directly contacting the light emitting unit 20, such that the red light with lower energy (e.g. 600 nm or more) is captured and accumulated therein (i.e. between the first surface 31 and the second surface 32 of the light transmitting unit 30), and the red light outputted from the light transmitting unit 30 has a certain light intensity. Furthermore, for the wavelength of the red light with lower energy, compared with the conventional scheme of directly entering the atmosphere, the light transmitting unit 30 further provides an optical cavity with lower refractive index variation, so as to avoid the loss of the output energy of the red light, and to improve the output intensity of the red light in the brand-new packaging type, thereby achieving the purposes of simple structure, easy production and low production cost.

Fig. 3 is a schematic cross-sectional view of a light emitting structure 3 according to a third embodiment of the present utility model; fig. 4 is a schematic top view of a light emitting structure 3 according to a third embodiment of the present utility model.

Referring to fig. 3 and 4 together, the light emitting structure 3 according to the third embodiment of the present utility model is substantially the same as the light emitting structure 1 according to the first embodiment and the light emitting structure 2 according to the second embodiment, but the light emitting structure 3 may further include a transparent cover 40.

In some embodiments, the transparent cover 40 is disposed above the carrying unit 10 and covers the light emitting unit 20 and the light transmitting unit 30, so as to protect the light emitting unit 20 and the light transmitting unit 30, but is not limited thereto.

In certain embodiments, transparent cover 40 may comprise glass, quartz, sapphire, etc., although this is not limiting.

In some embodiments, the transparent cover 40 includes at least one vent 41 adjacent to the periphery of the carrying unit 10 for allowing the gas 100 (e.g. air or inert gas) to flow inside and outside the transparent cover 40 to cool the light emitting unit 20, thereby increasing the lifetime and reliability of the light emitting unit 20, but is not limited thereto.

For this reason, the light emitting structure 3 of the present utility model is formed by the light transmitting unit 30 directly contacting the light emitting unit 20, such that the red light with lower energy (e.g. 600 nm or more) is captured and accumulated therein (i.e. between the first surface 31 and the second surface 32 of the light transmitting unit 30), and the red light outputted from the light transmitting unit 30 has a certain light intensity. Furthermore, for the wavelength of the red light with lower energy, compared with the conventional scheme of directly entering the atmosphere, the light transmitting unit 30 further provides an optical cavity with lower refractive index variation, so as to avoid the loss of the output energy of the red light, and to improve the output intensity of the red light in the brand-new packaging type, thereby achieving the purposes of simple structure, easy production and low production cost.

Further, in some embodiments, a transparent cover 40 can be covered outside the light emitting unit 20 and the light transmitting unit 30 to protect the light emitting unit 20 and the light transmitting unit 30.

Fig. 5 is a schematic cross-sectional view of a light emitting structure 4 according to a fourth embodiment of the present utility model.

Referring to fig. 5, the light emitting structure 4 of the fourth embodiment of the present utility model is substantially the same as the light emitting structure 1 of the first embodiment, but the light emitting structure 4 further includes a reflecting unit 50, and the carrying unit 10a is a lead frame (led frame) and may have a bowl-cup structure, and the central position of the carrying unit 10a carries the light emitting unit 20 and the light transmitting unit 30.

In some embodiments, the reflective unit 50 may include a white colloid made of a high-reflectivity polymer material or metal oxide (such as titanium dioxide TiO2, etc.) with white color, and the white colloid is disposed around the periphery of the light emitting unit 20 and the light transmitting unit 30, so as to increase the reflectivity of the periphery of the light emitting unit 20, and avoid the light intensity loss caused by the dissipation of part of the light energy from the periphery of the light emitting unit 20, but the utility model is not limited thereto.

In some embodiments, the cover plate structure is not designed for the bowl glass Lead Frame, because light loss is caused, the cover plate 60 is disposed over the carrying unit 10a to protect the light emitting unit 20, the light transmitting unit 30 and the reflecting unit 50, and a space 200 for accommodating the gas 100 is formed between the cover plate 60 and the carrying unit 10a, the light transmitting unit 30 and the reflecting unit 50, but not limited thereto.

For this reason, the light emitting structure 4 of the present utility model is formed by the light transmitting unit 30 directly contacting the light emitting unit 20, such that the red light with lower energy (e.g. 600 nm or more) is captured and accumulated therein (i.e. between the first surface 31 and the second surface 32 of the light transmitting unit 30), and the red light outputted from the light transmitting unit 30 has a certain light intensity. Furthermore, for the wavelength of the red light with lower energy, compared with the conventional scheme of directly entering the atmosphere, the light transmitting unit 30 further provides an optical cavity with lower refractive index variation, so as to avoid the loss of the output energy of the red light, and to improve the output intensity of the red light in the brand-new packaging type, thereby achieving the purposes of simple structure, easy production and low production cost.

It should be noted that the light emitting structure 4 of the present utility model includes the reflecting unit 50 disposed around the periphery of the light emitting unit 20, so that the energy waste caused by the dissipation of a part of the light outputted from the light emitting unit 20 from the side wall of the light emitting unit 20 can be avoided, the reflecting unit 50 limits the light emitting angle of the light emitting unit 20, and more light can enter the light transmitting unit 30, so that the illuminance of the light emitting structure 4 of the present utility model can be higher than that of the lighting product of the prior art.

In some embodiments, the light emitting module 4 of the present utility model achieves an increase in illuminance of at least 10% compared to a structure employing the reflection unit 50.

Fig. 6 is a schematic cross-sectional view of a light emitting structure 5 according to a fifth embodiment of the present utility model.

Referring to fig. 6, the light emitting structure 5 of the fifth embodiment of the present utility model is substantially the same as the light emitting structure 4 of the fourth embodiment, but the second surface 32 of the light transmitting unit 30 is a cambered surface according to the surface Zhang Lixing, and the reflecting unit 50 is only disposed around the periphery of the light emitting unit 20 and does not contact the light transmitting unit 30, so that the reflecting unit 50 is formed into another cambered surface according to the surface tension between the light emitting unit 20 and the carrying unit 10a, which is not limited thereto.

For this reason, the light emitting structure 5 of the present utility model is formed by the light transmitting unit 30 directly contacting the light emitting unit 20, such that the red light with low energy (e.g. 600 nm or more) is captured and accumulated therein (i.e. between the first surface 31 and the second surface 32 of the light transmitting unit 30), and the red light outputted from the light transmitting unit 30 has a certain light intensity. Furthermore, for the wavelength of the red light with lower energy, compared with the conventional scheme of directly entering the atmosphere, the light transmitting unit 30 further provides an optical cavity with lower refractive index variation, so as to avoid the loss of the output energy of the red light, and to improve the output intensity of the red light in the brand-new packaging type, thereby achieving the purposes of simple structure, easy production and low production cost.

It should be noted that the light emitting structure 5 of the present utility model includes the reflecting unit 50 disposed around the periphery of the light emitting unit 20, so that the energy waste caused by the dissipation of a part of the light outputted from the light emitting unit 20 from the side wall of the light emitting unit 20 can be avoided, the reflecting unit 50 limits the light emitting angle of the light emitting unit 20, and more light can enter the light transmitting unit 30, so that the illuminance of the light emitting structure 5 of the present utility model can be higher than that of the lighting product of the prior art.

Fig. 7 is a graph showing the relationship between the brightness ratio of the light emitting structures 1 to 5 and the thickness of the light transmitting unit 30.

Referring to fig. 1A to 7, the light transmitting unit 30 is configured to accumulate the light outputted from the light emitting unit 20 therein, and make the light outputted from the light transmitting unit 30 have a certain light intensity, such as the experimental value a and the trend line B shown in fig. 7. Further, the light transmitting unit 30 may be associated as an optical resonant cavity (optical resonator), and when the cavity volume of the optical resonant cavity is expanded, more light energy may be accumulated, so when the thickness of the light transmitting unit 30 is properly increased, the accumulated light energy may be increased, and thus the light intensity output from the light transmitting unit 30 may be further increased. In particular, for red light with lower energy (e.g., between 600 nm and 680 nm), increasing the thickness of the light transmitting unit 30 (e.g., between 0.05mm and 1.0 mm) can significantly increase the light intensity, such as the brightness to between 101% and 120%, but is not limited thereto.

In summary, the light emitting structure of the present utility model enables a red light wavelength (e.g. 600 nm or more) with low energy to be captured and accumulated therein by the light transmitting unit directly contacting with the light emitting unit, and enables the red light output from the light transmitting unit to have a certain light intensity. Furthermore, for the wavelength of the red light with lower energy, compared with the traditional scheme of directly entering the atmosphere, the light transmitting unit further provides an optical cavity with lower refractive index variation, thereby avoiding the loss of the output energy of the red light, improving the output intensity of the red light in the brand-new packaging type, and achieving the purposes of simple structure, easy production and low production cost.

In some embodiments, a transparent cover may be covered outside the light emitting unit and the light transmitting unit to protect the light emitting unit and the light transmitting unit. And the periphery of the transparent cover body adjacent to the bearing unit comprises at least one ventilation hole for enabling gas (such as atmosphere or inert gas) to circulate inside and outside the transparent cover body so as to cool the light-emitting unit and prolong the service life and reliability of the light-emitting unit.

In some embodiments, the light emitting structure of the present utility model includes a reflective unit disposed around the periphery of the light emitting unit, so that energy waste caused by dissipation of part of light output by the light emitting unit from the side wall of the light emitting unit can be avoided, the reflective unit limits the light emitting angle of the light emitting unit, and more light can enter the light transmitting unit, so that the illuminance of the light emitting structure of the present utility model can be higher than that of the lighting product of the prior art.

It should be noted that by properly increasing the thickness of the light-transmitting unit, the accumulated light energy can be increased, and the light intensity output from the light-transmitting unit can be further increased. In particular, for low energy red light (e.g., between 600 nm and 680 nm), increasing the thickness of the light transmissive unit appropriately may increase the light intensity more significantly.

Therefore, the light-emitting structure can solve the problem of red light brightness in a brand-new packaging type of non-packaging adhesive brightening, thereby improving the output intensity of the light-emitting structure and achieving the purposes of simple structure, easy production and low production cost.

Of course, the present utility model is capable of other various embodiments and its several details are capable of modification and variation in light of the present utility model, as will be apparent to those skilled in the art, without departing from the spirit and scope of the utility model as defined in the appended claims.

Claims

1. A light emitting structure comprising:

a bearing unit;

the light-emitting unit is arranged on the bearing unit and comprises a light-emitting surface; and

a light transmitting unit directly contacting the light emitting unit and comprising a first surface and a second surface opposite to each other;

the first surface is covered on at least part of the light-emitting surface, and the second surface is directly contacted with a gas.

2. The light-emitting structure according to claim 1, wherein the light-transmitting unit covers the light-emitting unit in an area of 0.8 to 1.2 times the area of the light-emitting surface.

3. The light-emitting structure of claim 1, further comprising:

the reflecting unit is arranged on the bearing unit and is annularly arranged on the periphery of the light-emitting unit.

4. The light-emitting device according to claim 3, wherein the reflective unit comprises a white gel, and the white gel is disposed around the periphery of the light-transmitting unit.

5. The light emitting structure of claim 1, wherein the second surface of the light transmitting unit is formed as a plane or as a cambered surface according to surface tension.

6. The light-emitting structure of claim 1, further comprising:

the transparent cover body is arranged on the bearing unit and covers the light-emitting unit and the light-transmitting unit.

7. The light-emitting structure according to claim 6, wherein the transparent cover comprises at least one vent hole adjacent to the periphery of the carrying unit.

8. The light emitting structure of claim 1, wherein the gas comprises an inert gas or an atmosphere.

9. The light emitting structure of claim 1, wherein the carrier unit comprises a substrate or a lead frame.

10. The light-emitting structure according to claim 1, wherein a peak emission wavelength of the light-emitting unit is greater than or equal to 600 nm, and a refractive index of the light-transmitting unit is greater than or equal to 1.3.