KR20110007705A - LED phosphor density measuring apparatus and method - Google Patents

Abstract

PURPOSE: A device and a method for measuring the density of an LED fluorescent substance are provided to effectively extract light and enable the formation of LED package in which characteristic value between products is uniform. CONSTITUTION: A device for measuring the density of an LED fluorescent substance comprises a light source(100), a light sighting device(101), and a light receiving module(300), and a spectrometer(400). The light sighting device emits the light in a dispenser and a fluorescent substance(201) injected into a dispenser nozzle(202). The light receiving module comprises a light receiving sighting device to receive light penetrating the dispenser and the dispenser nozzle. The spectrometer is connected to the light receiving module. The spectrometer outputs spectral characteristic data(401) according to the fluorescent substance density in real time.

Description

LED phosphor density measuring apparatus and method

The present invention relates to a device and method for measuring the density of LED phosphors, and more particularly, to effectively extract light and detect color purity by detecting a change in phosphor density dispersed in a silicone (or epoxy) resin in a dispenser in an LED packaging process. The present invention relates to an LED phosphor density measuring apparatus and method for ensuring an excellent LED package with excellent characteristic values (color coordinates) between products.

Light emitting diodes (hereinafter, referred to as LEDs) are semiconductor devices capable of realizing various colors. LED is used as a light source of various colors because the light emitting source can be configured by changing compound semiconductor materials such as GaAs, AlGaAs, GaN, InGaN and AlGaInP.

As the demand for high power and high brightness LEDs, such as white LEDs for lighting, increases, such LEDs are being actively researched to improve the performance and reliability of LED packages.

In order to improve the performance of the LED products, together with the LED chip itself having excellent light efficiency, the LED package must be secured at the same time to extract the light effectively, excellent color purity and uniform characteristics between the products.

In order to obtain white light using an LED, a phosphor (for example, a yellow phosphor, etc.) is usually applied onto a blue or ultraviolet LED chip. The quality of this white light is greatly influenced not only by the characteristics of the phosphor itself to be applied, but also by the distribution form of the phosphor.

Indeed, in the traditional LED package process in which a mixture of transparent resin and phosphor powder is injected into a cup of a package in which an LED chip is mounted, it is quite difficult to uniformly control the spatial distribution of the phosphor in the resin encapsulant. That is, since the density of the phosphor coated on the LED chip is uneven, the color coordinate deviation of the output light is severe, and color separation or color staining phenomenon is likely to occur.

1 is a cross-sectional view illustrating a conventional LED package manufacturing process. Referring to Fig. 1 (a), a package main body having a reflection cup 11a and a lead frame 12a and 12b inserted therein is prepared. As shown in Fig. 1 (b), The blue LED chip 15 is mounted on the bottom of the reflecting cup 11a, and the LED chip 15 and the lead frames 12a and 12b are connected by a wire 16 or the like. As shown in the drawing, phosphor resin 18 such as silicon (or epoxy) in which yellow phosphor 17 is dispersed is injected into a reflecting cup to seal the LED chip 15 and to cure the phosphor resin 18 by heating.

In order to form the phosphor resin layer 18 in such an LED package process, various methods are adopted by manufacturers.

Among them, a widely used method is a method of injecting a phosphor resin in a quantity around the LED chip 15 using a dispenser (injector). Devices that use this method are commonly referred to as dispensers.

Phosphor and silicon (or epoxy) are put into the dispenser and discharged by a predetermined amount. The phosphor injected into the dispenser is precipitated downward as time passes (eg, several tens of minutes to several hours).

This results in a change in phosphor density in the silicon (or epoxy) even though the silicon (or epoxy) must be evenly mixed. That is, the phosphor particles sink in the dispenser as time passes, adversely affecting product characteristic values (color coordinates).

Therefore, even if the same dispenser is discharged by a certain amount, if you look at the color coordinates of the LED package using the same dispenser, deviation occurs between each other, LED packages with a large deviation of the color coordinates with other LED packages are classified as extraneous products. Irregular products continue to occur.

However, in manufacturing LED packages using current dispensers, to maintain uniformity of phosphor particles injected into the dispenser to reduce extraneous products (defective products), adjust the viscosity according to the viscosity and viscosity of the host and hardener, and change the working environment. Particular attention is paid to the amount adjustment according to, but there is a problem that it is virtually impossible to reduce the incidence of isochronous products because the color coordinate distribution described above is wide.

The present invention is to solve the above problems, in the LED package process in advance to detect the change in the phosphor density of the silicon (or epoxy) in the dispenser to effectively extract the light, excellent color purity, and the characteristic value between the products ( It is an object of the present invention to provide an LED phosphor density measuring apparatus and method for securing a uniform LED package.

The present invention includes a light source for irradiating light to a dispenser injected with an LED phosphor resin, a light receiving module for receiving the transmitted light transmitted through the dispenser, and a spectrometer connected to the light receiving module to output the spectral characteristic data of the transmitted light. An LED phosphor density measuring apparatus and method characterized in that the configuration is a problem solving means.

LED phosphor density measuring apparatus and method according to the present invention in the LED package process by detecting the change in the phosphor density of the silicon (or epoxy) in the dispenser in advance to effectively extract the light, excellent color purity and characteristics value between the products ( In addition to producing a uniform LED package (color coordinates), there is a significant effect that can significantly reduce the amount of phosphor resin discarded.

Currently, white LED devices use blue LED chips and phosphors emitting yellow light, and yttrium-aluminum-garnet (Y 3 Al 5 O 12: Ce, YAG) compounds are generally used as yellow phosphors.

The white LED emission principle is that when InGaN-based blue LEDs having a wavelength of 450 nm are irradiated to YAG-based phosphors, part of the blue light generated from the blue LEDs excites the YAG-based phosphors to generate yellow-green fluorescence, and the blue and yellow-green compounds are synthesized. To emit white light.

On the other hand, since the white LED using the blue LED chip and the YAG-based phosphor uses only one phosphor, there is a problem in that it is difficult to manufacture a large number of white LED devices having excellent optical characteristics and uniformity. Forming technology is being developed one after another.

That is, a white LED is formed using a mixture of green phosphors such as Sr _1-x S _x : Eu in the YAG phosphor to form white light from a combination of light emitted from a B-LED chip, a YAG yellow phosphor, and a green phosphor. have.

In addition, a yellow phosphor configured to use a UV radiation source having a wavelength in the range of about 250 to 420 nm as an excitation light source and to emit light having a peak intensity at a wavelength in the range of 530 to 590 nm and at a wavelength in the range of 470 to 530 nm White LEDs have also been developed that include blue phosphors configured to emit light having peak intensity.

The LED phosphor composition is a white LED using a YAG-based phosphor as an example. The yellow phosphor, a silicone (thermosetting) resin, a curing agent, and a dispersant (nano powder) have a viscosity of about 1,000 to 10,000 cp. In the process, it is cured by coating on the LED chip from the dispenser.

In this case, the tack time is generally about 2 seconds (0.5 seconds movement + 1.5 seconds injection), and one dispenser syringe is injected 30 minutes per minute, and usually 2 to 4 syringes are simultaneously moved and dispensing. After injection, problems of density change and dispersibility due to phosphor sedimentation of the phosphor resin occur.

At this time, 30% of all LED defects are related to phosphor color coordinates, and 20% of them are due to poor dispersion, nano powder agglomeration, streaks, and interlayer separation.

Therefore, when the phosphor is applied to the LED, the phosphor density change in the dispenser syringe and / or injection nozzle is detected in real time, an alarm is generated when there is a density change, and the dispenser is replaced with a color coordinate when the phosphor resin is injected before the density change. The present invention has been completed by focusing on the fact that a uniform LED package can be manufactured.

The schematic principle and conceptual diagram of the LED phosphor density measuring apparatus and method of the present invention will be described with reference to the following figure, which irradiates a yellow phosphor in a dispenser with a light such as a blue LED from a light source through a collimator, The transmitted light may be received by a spectrometer to output spectral characteristic data according to the normal phosphor density of the yellow phosphor resin in the dispenser in real time.

Figure 2 shows the emission spectrum of the white LED device made of a blue light emitting diode + YAG-based phosphor, Figure 3 shows the area of white light appearing on the CIE chart.

 In FIG. 2, the B-LED represents a blue light emitting diode, and the Y-phosphor represents yellow, in which some blues are wavelength-converted by the YAG-based phosphor. White light appears in the W region along the connecting line between B-LED and Y-phosphor.

As described above, when the phosphor density in the dispenser changes as time passes, the spectral characteristic data is changed accordingly, and thus the density change is measured in real time by comparing the changed spectrum with the normal spectrum using the LED phosphor density measuring apparatus of the present invention. It can be monitored, and if there is a change in density, an alarm will be generated, and uniform color coordinates can be obtained by replacing the dispenser.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

A first embodiment of the present invention will be described with reference to FIG. 4. In the LED phosphor density measuring apparatus of the present invention, a light collimator for irradiating light to the light source 100 and the phosphor 201 injected into the dispenser 200 is provided. And a light receiving module 300 having a light receiving collimator 101 for receiving the transmitted light passing through the dispenser, and a light receiving module 300, and real-time spectral characteristic data 401 according to the phosphor density. It characterized in that it comprises a spectrometer (spectrometer) (400) for outputting.

Looking at the operation of the LED phosphor density measuring device, when the light from the light source 100 is irradiated to the phosphor 201 injected into the dispenser 200 through the collimator 101, the light passing through the dispenser is a light collimator 101 Received by the light receiving module 300, the transmitted light can be output in real time the spectral characteristic data 401 according to the yellow phosphor density in the spectrometer (400).

It is preferable to use Blue LED or UV-LED as the light source 100.

The LED phosphor density measuring apparatus may further include an alarm generator (not shown) for generating an alarm when the phosphor density in the dispenser is changed and the spectral characteristic data in the spectrometer 400 is changed.

In addition, the LED phosphor density measuring device further comprises a color coordinate system converter 501 that can measure the color coordinates corresponding to the spectral characteristic data 401 output from the spectrometer 400.

The color coordinate system converting apparatus 501 can be used as long as the apparatus can output the color coordinates using the color coordinate system conversion method using the color matching function (Color Matching Function) output from the spectrometer 400.

The conversion method of the color coordinate system using the Color Matching Function will be described with reference to the following figure.

When spectral data having wavelengths of x, y, and z regions is output from the spectrometer 400, the integral function for each region for each wavelength is obtained as described above, and the x, y, z region values are calculated and the CIE color coordinate system is calculated. Converting to gives the following color coordinate system:

Where x = X / (X + Y + Z), y = Y / (X + Y + Z), z = Z / (X + Y + Z), and x + y + z = 1, k Is the wavelength correction constant

In the color coordinate system conversion method using the color matching function, the relationship between the wavelength and the color coordinate region may be illustrated as follows.

On the other hand, the LED phosphor density measuring device may be configured in addition to the dispenser nozzle 202 as shown in Figure 4 in parallel with the case where it is applied to the dispenser.

In this case, the phosphor density in the dispenser and the change in spectral characteristic data and the corresponding change in spectral characteristic data in the dispenser nozzle can be monitored simultaneously with the change in the phosphor density in the dispenser and thus the change in the spectral characteristic data. It is possible to detect the change in the density of the phosphor more precisely because it can monitor by comparing the change in the density of the phosphor.

A second embodiment of the present invention relates to a method for measuring the density of an LED phosphor, comprising: a first step of irradiating light injected into a dispenser through a collimator at a light source; A second step of receiving the light passing through the dispenser to the light receiving module including the light receiving collimator; And the third step of outputting the received spectral characteristic data according to the phosphor density in real time in a spectrometer.

It is preferable to use Blue LED or UV-LED as the light source.

The LED phosphor density measuring method may further include a fourth step of generating an alarm when the phosphor density in the dispenser is changed after the third step so that the spectral characteristic data is changed in the spectrometer.

The LED phosphor density measuring method may further include a fourth step of converting the spectral characteristic data output from the spectrometer into a color coordinate system after the third step.

On the other hand, the LED phosphor density measurement method may be configured by further adding a method of measuring in the dispenser nozzle in parallel with the method of measuring in the dispenser.

That is, a more precise phosphor density change can be detected by comparing the phosphor density in the dispenser with the phosphor density change of the dispenser nozzle.

<Examples>

1. Spectrum Measurement

As shown in FIG. 5, the yellow phosphor resin sample is divided into A-> D regions as time elapses, so that precipitation and interlayer separation of the phosphor occur and a change in the concentration of the phosphor occurs.

As shown in FIG. 6, the spectrum in the A, B, C, and D regions was measured using the LED phosphor density measuring apparatus of the present invention.

2. Spectrum output

Spectral measurement results in areas A, B, C, and D were output from the spectrum data of FIGS. 7 to 10.

3. Spectrum  Observation of the measurement result

7 to 10, the emission spectra was observed in the band of about 500 nm to 700 nm by the blue LED.

It can be seen that Blue Spectrum is mainly formed in area A (-> area where phosphor is hardly present). It can be seen that the spectra of the form occurs, and at the same time, as the concentration of the yellow phosphor increases, the intensity peak of the transmitted blue spectrum decreases so that the density change of the phosphor can be detected in real time.

The present invention described above is not limited to the embodiments and the accompanying drawings, and various forms of substitution, modification, and alteration are possible without departing from the technical spirit of the present invention described in the claims. It will be self-evident to those who have knowledge of.

1 is a cross-sectional view illustrating a manufacturing process of an LED package according to a conventional example.

2 is a white LED emission spectrum formed of a blue light emitting diode + YAG-based phosphor

3 is a view showing an area of white light appearing on a CIE chart

4 is a block diagram of an LED phosphor density measuring apparatus according to the present invention

5 is a state diagram of the occurrence of precipitation and interlayer separation of the phosphor;

6 is a state diagram of the LED phosphor density measurement of the present invention

7 to 10 are spectrum data according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: light source 101: light collimator

200: dispenser 201: phosphor

300: light receiving module 400: spectrometer

401: spectrum characteristic data 501: color coordinate system converter

Claims (8)

A light sight 101 for irradiating light to the light source 100, the dispenser 200 and / or the phosphor 201 injected into the dispenser nozzle 202, and the dispenser 200 and / or dispenser nozzle 202. A light receiving module 300 having a light receiving collimator 101 for receiving the transmitted light transmitted through the light, and a spectrometer connected to the light receiving module 300 to output spectral characteristic data 401 according to the phosphor density in real time. LED phosphor density measurement device, characterized in that comprises (400) The method of claim 1, LED light source density measuring device, characterized in that the light source 100 uses a blue LED or UV-LED The method of claim 1, The LED phosphor density measuring device further includes an alarm generator configured to generate an alarm when the phosphor density of the dispenser 200 and / or the dispenser nozzle 202 is changed and the spectral characteristic data is changed in the spectrometer 400. LED phosphor density measuring device, characterized in that The method according to any one of claims 1 to 3, The LED phosphor density measuring device further comprises a color coordinate system conversion device 501 capable of measuring the color coordinates corresponding to the spectral characteristic data 401 output from the spectrometer 400 is characterized in that the LED phosphor density measurement Device Irradiating light from a light source to a phosphor injected into the dispenser and / or the dispenser nozzle through a light collimator; A second step of receiving light passing through the dispenser and / or the dispenser nozzle by a light receiving module having a light collimator; And a third step of outputting the spectral characteristic data according to the phosphor density of the received transmitted light in real time from a spectrometer. The method of claim 5, LED light source density measurement method characterized in that the light source uses a blue LED or UV-LED The method of claim 5, The LED phosphor density measuring method further includes a fourth step of generating an alarm when the phosphor density of the dispenser and / or the dispenser nozzle is changed after the third step so that the spectral characteristic data is changed in the spectrometer. LED phosphor density measurement method The method according to any one of claims 5 to 7, The LED phosphor density measuring method further comprises a color coordinate system converting step of measuring a color coordinate corresponding to the spectral characteristic data output from the spectrometer following the third step.

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