KR20130073798A - Method of manufacturing a light emitting device and apparatus for measuring a phosphor film - Google Patents

Abstract

The method of manufacturing a white light emitting device includes: dividing a phosphor sheet into unit fluorescent films to be applied to individual LED devices, measuring light conversion characteristics of each unit fluorescent film, and measuring results of the light conversion characteristics; Classifying the unit fluorescent film of the phosphor sheet into a plurality of groups, and combining the unit fluorescent film divided into the plurality of groups with an LED element having a predetermined optical characteristic so as to obtain a target color characteristic.

Description

Manufacture method of light emitting device and fluorescent film measuring device {METHOD OF MANUFACTURING A LIGHT EMITTING DEVICE AND APPARATUS FOR MEASURING A PHOSPHOR FILM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a light emitting device, and more particularly, to a method of manufacturing a light emitting device having a fluorescent film and a fluorescent film measuring apparatus that can be used therein.

Light Emitting Diode (hereinafter referred to as 'LED') is a semiconductor device that converts electrical energy into optical energy, and is composed of a compound semiconductor that emits light of a specific wavelength according to an energy band gap. Its use is expanding from the back light unit (BLU) for displays and LCDs to computer monitors.

In general, a white light emitting device may employ a suitable wavelength conversion unit together to provide white light. The wavelength conversion part is manufactured by using a phosphor on an LED chip or wafer using a known process such as dispensing or printing at the package level or wafer level, or after the phosphor is prefabricated into a fluorescent film such as a sheet, and then the LED chip or wafer. A method of attaching to the same may also be provided.

However, even when the light emitting device is manufactured by the same process, since the light emitting device has different white light characteristics depending on the manufacturing process and the conversion characteristics of the phosphor (film), there is a problem that non-uniform color scattering occurs in the entire product.

Furthermore, in some cases, some light emitting diode packages may have white light that deviates from the condition of the desired target color characteristics, and thus may be discarded as defective and lower the yield.

There is a need in the art for a method of manufacturing a light emitting device and a fluorescent film measuring apparatus for improving the reliability of measuring light conversion characteristics of a fluorescent film to improve color scattering or to control precise color characteristics.

According to an aspect of the present invention, according to the step of dividing the phosphor sheet into a unit fluorescent film to be applied to an individual LED device, measuring the light conversion characteristics of each unit fluorescent film, and the measurement result of the light conversion characteristics, Classifying the unit fluorescent film of the phosphor sheet into a plurality of groups, and combining the unit fluorescent film divided into the plurality of groups with an LED element having a predetermined optical characteristic to obtain a target color characteristic. A light emitting device manufacturing method is provided.

The measuring of the light conversion characteristics may include adjusting a beam size of a reference light source using an optical system, irradiating the adjusted size beams to the unit fluorescent layers, and converting the beams by the irradiated beams. Detecting detected light.

In this case, the adjusted beam size may be smaller than the area of the unit fluorescent film.

In one example, the detector used in the detecting step may be located on the opposite side of the surface irradiated with the reference light source. In another example, the detector used in the detecting step may be located on a surface to which the reference light source is irradiated.

The reference light source may be an ultraviolet or blue light source.

Separating the phosphor sheet into a unit fluorescent film may include attaching the phosphor sheet to an adhesive sheet, and cutting the phosphor sheet into the unit fluorescent film. Here, the adhesive sheet may be a light transmissive sheet.

In an example, before the measuring of the light conversion characteristic, the method may further include separating each of the cut unit fluorescent films from the phosphor sheet and loading the cut unit fluorescent film at a position for measuring the light conversion characteristic.

Alternatively, prior to the step of measuring the light conversion characteristics, further comprising the step of loading the phosphor sheet in a position for measuring the light conversion characteristics, the step of measuring the light conversion characteristics, each unit fluorescent film is Moving the phosphor sheet to be in position for measuring light conversion properties.

The classifying the unit fluorescent film into a plurality of groups may include separately unloading the measured unit fluorescent film so as to be located in different regions according to the measured light conversion characteristics.

After measuring the light conversion characteristics, further comprising the step of cutting the phosphor sheet into the unit fluorescent film, wherein the step of classifying the unit fluorescent film into a plurality of groups, different according to the measured light conversion properties Separating each of the unit fluorescent layers by separating from the phosphor sheet so as to be located in an area.

The LED device may be an LED chip or an LED package. The optical conversion characteristic may include color coordinates, and the optical characteristic of the LED device may include at least one of peak wavelength and light output.

According to another aspect of the invention, the reference light source for emitting a beam having a predetermined wavelength, and guides the beam emitted from the reference light source to be irradiated to the fluorescent film to be measured, the individual LED device at the measurement position of the fluorescent film A beam adjusting optical system that adjusts a beam spot size to have a size smaller than an area of a unit fluorescent film to be applied to the light source, a detection unit that detects light beam irradiated from the fluorescent film, and measures light conversion characteristics of the detected light Provided is a fluorescent film measuring apparatus including a light conversion characteristic measuring unit.

In one example, the detector may be located on the opposite side of the surface to which the beam is irradiated with respect to the fluorescent film. In another example, the detector may be located on a surface to which the beam is irradiated based on the fluorescent film.

The fluorescent film to be measured may be a phosphor sheet divided into a plurality of unit fluorescent films, and may further include a phosphor film moving unit for moving the phosphor sheet so that each unit fluorescent film is positioned at the measurement position.

The fluorescent film to be measured may be the unit fluorescent film separated from the phosphor sheet, and may further include a loading unit separating the unit fluorescent film from the phosphor sheet and loading the unit fluorescent film at the measurement position.

The apparatus may further include an unloading unit which individually unloads the measured unit fluorescent film so as to be located at different regions according to the measured light conversion characteristics.

Precise control of color characteristics is possible by classifying the photoconversion characteristics of the fluorescent film into unit fluorescent films to be applied to individual LED devices and separately measuring and classifying them. In addition, by combining with the LED device having a specific optical characteristic to satisfy the target color coordinates, the color scatter can be improved even more.

In addition, not all the features of the present invention are enumerated in the above-described solutions and effects. The various features of the present invention and the advantages and effects thereof will be more fully understood by reference to the following specific embodiments.

1 is a flowchart illustrating an example of a method of manufacturing a white light emitting device according to the present invention.
2 shows a schematic diagram of a fluorescent film measuring apparatus according to an embodiment of the present invention.
3A and 3B are photographs and schematic diagrams showing the relationship between the unit fluorescent film and the beam size used in the present invention.
4 shows a schematic view of a fluorescent film measuring apparatus according to another embodiment of the present invention.
5 and 6 are schematic diagrams showing various examples of the phosphor measuring device according to the present invention (differences in handling of a fluorescent film).
7 is a CIE 1931 color coordinate system showing a result of classification of a fluorescent film in a method of manufacturing a white light emitting device according to an embodiment of the present invention.
FIG. 8 is a CIE 1931 color coordinate system showing color coordinates of white light generated from a white light emitting device manufactured from the fluorescent film classified in FIG.
FIG. 9 is a CIE 1931 color coordinate system showing color coordinates of white light of a white light emitting device manufactured from the fluorescent film classified in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating an example of a method of manufacturing a white light emitting device according to the present invention.

As shown in FIG. 1, the manufacturing method according to the present example may begin with a step S12 of dividing a phosphor sheet into a “unit fluorescent film”.

As used herein, the term "unit fluorescent film" means a fluorescent film to be applied to an individual LED device. Such a unit fluorescent film may be defined in different shapes and / or different sizes depending on the device applied thereto, and may be applied to, for example, directly applied to an LED chip or may be applied to a specific area such as a resin packaging part of an LED package. It may be defined differently according to the shape and size of the region to be applied.

The step of dividing the phosphor sheet into the unit fluorescent film may include not only physical processing (eg, cutting or cutting) to divide into a plurality of unit fluorescent films, but also a visual display or a virtual partition for such a partition. have.

The process of cutting the phosphor sheet into the unit fluorescent film may be performed in a state in which the phosphor sheet is attached to an adhesive tape. In this case, since the unit fluorescent film can maintain the original position before cutting on the phosphor sheet by the adhesive tape, it is possible to easily handle the phosphor sheet or each unit fluorescent film.

Subsequently, light conversion characteristics of each unit fluorescent film of the phosphor sheet may be measured (S14).

The light conversion characteristics of the unit fluorescent film measured in this step may typically be color characteristic values such as color coordinates. In this embodiment, the light conversion characteristics can be measured for each unit fluorescent film instead of any point of the phosphor sheet. The measuring step may be performed by irradiating the beam of the reference light source to the individual unit fluorescent film and measuring the characteristic of the light converted therefrom.

In order to obtain accurate light conversion characteristic information for the unit fluorescent film, the beam of the reference light source may be adjusted to have at least a smaller size than the unit fluorescent film. In order to adjust the beam size, a beam control optical system for condensing may be provided between the reference light source and the unit fluorescent film. As described above, even if the beam size is reduced so that each unit fluorescent film can be independently measured, the beam area is preferably 10% or more of the area of the unit fluorescent film in order to increase the evaluation reliability of the unit fluorescent film.

Next, the unit fluorescent film of the phosphor sheet may be classified into a plurality of groups according to the measurement result of the light conversion characteristic (S16).

For example, the classification process may be performed by defining a chromaticity region represented by color coordinates in a plurality of groups, and each unit fluorescent film is assigned to and classified into each grouped into chromaticity regions along the measured color coordinates. Here, each group divided according to the chromaticity region is also referred to as "bin", this classification process is also referred to as "binning".

The unit fluorescent film obtained from a plurality of phosphor sheets obtained in a single process may have a certain degree of deviation in the measured light conversion characteristics of the plurality of unit fluorescent films obtained from one phosphor sheet as well (see FIG. 7).

Unlike in the present embodiment, when measuring any point of the phosphor sheet and measured in the unit of the phosphor sheet, the deviation appearing in the unit phosphor film can be ignored, and as a result, it is difficult to expect precise chromaticity control in the final white light emitting device.

On the other hand, as in the present embodiment, since each unit fluorescent film is measured and divided into predetermined groups, disadvantageous effects (eg, color scattering) due to the deviation of the unit fluorescent film can be alleviated. Specifically, a white light emitting device having a target color characteristic may be manufactured by combining unit fluorescent films of each group with an LED element having appropriate optical characteristics in the next step S18.

To this end, the LED device may also be classified in advance by measuring each optical characteristic. The optical characteristics of the LED device may be characteristic values such as peak wavelength and light output. The target color characteristic may be represented by an area specified by color coordinates. A plurality of groups defined by a predetermined section expressed by such characteristic values may be set, and the LED elements may be previously classified into each group.

The unit fluorescent film classified in the previous step may be matched with a specific group of the LED element so as to satisfy the target color characteristic condition. Correlation for such matching can be obtained through experiments with samples in advance.

For example, a change in the color coordinate of the final white light is confirmed by changing at least one of the peak wavelength and the output of the LED device combined with the converted optical color coordinates of the reference fluorescent light source of the unit fluorescent film, and the final white light satisfies the desired target color coordinate region. By finding the characteristic condition of the LED device, it is possible to secure the correlation between the characteristics to obtain the target color coordinate region in the actual matching. This will be described in more detail with reference to FIG. 8.

In another aspect of the present invention, a novel fluorescent film measuring apparatus is provided. The fluorescent film measuring apparatus may be usefully used in the method of manufacturing the white light emitting device described above.

2 shows a schematic diagram of a fluorescent film measuring apparatus according to an embodiment of the present invention.

The fluorescent film measuring apparatus 20 shown in FIG. 2 is configured to guide the beam of the reference light source to be irradiated to the reference light source 24 emitting a beam having a predetermined wavelength and the fluorescent film 21 to be measured. The optical system 25 is included.

The reference light source 24 may be an ultraviolet light source or a blue light source as a short wavelength light source that emits light having a specific wavelength. Specifically, the reference light source 24 may be a light source of a known type such as an LED light source and a halogen light source.

In addition, the fluorescent film measuring apparatus 20 includes a detector 27 which detects light converted by being irradiated to the fluorescent film 21. The detector 27 may be connected to an optical conversion characteristic measuring unit (not shown) for measuring conversion characteristics of the detected converted light.

The fluorescent film 21 to be measured may be a phosphor sheet divided into unit fluorescent films, or may be an individual unit fluorescent film separated from the phosphor sheet. Even if the object to be treated is the phosphor sheet itself, one of the plurality of unit fluorescent films partitioned from the phosphor sheet will be disposed at one measurement position.

As such, the fluorescent film measuring apparatus 20 needs to adjust the beam spot size to a smaller size at the measurement position in order to measure the unit fluorescent film to be applied to the individual LED elements. FIG. 3A is a photograph showing such a practical example, and FIG. 3B is a schematic diagram showing in detail the outline of the unit fluorescent film P and the beam BS in the photograph of FIG. 3A. As illustrated, when the beam BS to be irradiated is adjusted to a small size d so that the irradiated beam BS may be located in the unit fluorescent film P, the converted light obtained by transmitting only the unit fluorescent film P region may be effectively measured. have.

In order to adjust the beam size, the optical system 25 may be a beam adjusting optical system that adjusts the spot size required for the beam to be irradiated to the unit fluorescent film. As shown in FIG. 2, the beam adjusting optical system is illustrated as being composed of a plurality of lenses 25a, 25b, and 25c arranged side by side on an optical axis, but is not limited thereto and may have optical systems having various condensing structures known in the art. have.

In the present embodiment, the detection unit 27 may be located on the opposite side of the surface to which the beam is irradiated based on the fluorescent film 21. That is, the fluorescent film measuring apparatus 20 may have an array for receiving the light converted through the fluorescent film 22.

The fluorescent film measuring apparatus according to the present invention may be implemented in a form having another arrangement shown in FIG. The fluorescent film measuring apparatus 40 according to this embodiment is shown in FIG.

The fluorescent film measuring apparatus 40 shown in FIG. 4 has a structure similar to the above embodiment, but the position of the detector 47 may be located on the surface to which the beam is irradiated with respect to the fluorescent film 41.

In this embodiment, the reflecting plate 43 can be arranged on the opposite surface of the fluorescent film 41 so that the converted light propagates on the beam irradiation surface. In order to avoid interference with the irradiated beam, the detector 47 may be disposed at a position inclined at a predetermined angle θ with respect to the beam irradiation surface of the fluorescent film 41. For example, the inclination angle θ of the detector 47 may be about 30 ° or less.

In addition to the measurement and classification method of the manufacturing method of the white light emitting device according to an aspect of the present invention, the fluorescent film measuring apparatus according to another aspect of the present invention is modified in various forms due to the difference in the way of handling the unit fluorescent film to be measured Can be. This will be described with reference to various examples of the phosphor measuring apparatus shown in FIGS. 5 and 6.

 The fluorescent film measuring apparatus 50 shown in FIGS. 5 and 6 includes a reference light source 54 for emitting a beam L1 having a predetermined wavelength, and an optical system for guiding the beam L1 of the reference light source 54. And 55. In addition, the fluorescent film measuring apparatus 50 includes a detector 56 that focuses the converted light L2, and a light conversion measurement unit 57 that is connected to the detector 56 and measures the converted light L2. It includes.

As illustrated, the detector 56 may be an integrating sphere, which is a kind of a spherical photometer having a structure in which light incident to the incident window is repeatedly diffused and reflected to the photometric window using the internal reflection side.

Regarding each component employed in the present embodiment, the opposite description can be understood with reference to the description of the corresponding element of the foregoing embodiment. In the present embodiment, the detector 56 may be located on the opposite side of the surface to which the beam of the reference light source 54 is irradiated, similar to the form shown in FIG. 2.

First, the fluorescent film measuring apparatus shown in FIG. 5 may include a loading unit (not shown) to load the phosphor sheet 51 attached to the adhesive tape 52 at the measurement position before measuring the light conversion characteristic. . The loading unit may measure light conversion characteristics of each unit fluorescent film by moving the phosphor sheet 51 so that each unit fluorescent film of the phosphor sheet 51 is placed at a measurement position. In this case, although not shown, the fluorescent film measuring apparatus 50 can move the phosphor sheet 51 to be measured in the horizontal direction (xy) so that each unit fluorescent film P can be measured in turn. It may further include a vehicle.

The phosphor sheet 51 employed in the present embodiment may be in a state in which the phosphor sheet 51 is cut into the unit phosphor film P, but if necessary, the phosphor sheet 51 may be divided into the unit phosphor film P virtually in a state in which the phosphor sheet 51 is not individually cut. Individual measurement of the membrane P may be ensured. In the latter case, an additional adhesive tape may not be required.

On the contrary, the fluorescent film measuring apparatus shown in FIG. 6 includes a loading unit (not shown), and the unit fluorescent film P cut from the phosphor sheet 61 is measured before the measuring of the light conversion characteristic. Each can be separated and loaded into the measuring position. In this case, the fluorescent film measuring apparatus may be provided with a separate support 53 so that the unit fluorescent film P may be disposed at the measurement position. The support 53 may be made of a light transmissive material so that the beam of the reference light source 54 is transmitted.

As in the present embodiment, when the unit fluorescent film P is measured individually, the fluorescent film measuring apparatus includes an unloading unit (not shown) to unload the measured unit fluorescent film P individually. And may be arranged in different areas according to the measured light conversion characteristics. Through this process, the classification process can proceed. Of course, the loading unit and the unloading unit may be implemented as a single device. The unloading process may be applied even when the phosphor sheet is cut into the unit fluorescent film even in the form shown in FIG. 5.

Hereinafter, a method of measuring and classifying a fluorescent film and a matching method of LED devices will be described through specific embodiments of the present invention.

<Measurement and classification example of fluorescent film>

Using a 350 nm near-ultraviolet LED as a reference light source, measurement and classification were carried out on the ceramic phosphor sheet containing the yellow phosphor as follows.

First, the ceramic phosphor sheet was attached to a transparent adhesive sheet, cut into a plurality of unit fluorescent films to be applied to the LED chip, and the color coordinates of the light converted from each unit fluorescent film were measured.

As a result, the color coordinates of the light converted from each unit fluorescent film were displayed in the CIE 1931 color coordinate system shown in FIG. In the CIE 1931 color coordinate system shown in FIG. 7, a plurality of bins represented by color gamuts distributed in a diagonal direction are displayed. The color gamut of each bin is defined as a four-point color coordinate area, respectively, and the plurality of bins are continuously distributed.

These bins are divided into color coordinate regions in which the optical characteristics of the LED elements need to be distinguished and matched to obtain the color coordinates of the desired target white light.

As shown in FIG. 7, most of the unit fluorescent films were divided into bins 6 and 7, and even some showed relatively wide distributions over bins 4 and 8. Thus, despite the unit fluorescent film obtained from the same phosphor sheet, it was confirmed that the color coordinates of the light obtained when using the reference light source having the same optical characteristics showed a relatively large deviation.

Some of the unit fluorescent films classified as Bin 4 to Bin 8 are extracted and applied to a blue LED chip having the same optical characteristics (peak wavelength: 455 nm, light output: 143mW), and the color coordinates of the white light are applied to the coordinate system shown in FIG. Shown in While bin 5 and bin 6 relatively satisfied the target color coordinate region, it was confirmed that some of the bins 6 and 7 were adjacent to the boundary of the target color coordinate or exhibited yellowish orange shifts.

As shown in FIG. 8, as shown in FIG. 7, similar color scattering trends were exhibited in the diagonal direction. In other words, it was confirmed that other light conversion characteristics of the unit fluorescent film had a great influence on the final white light.

< LED  With element matching >

As shown in FIG. 8, the unit fluorescent film classified into each group (empty) showed a difference in light conversion characteristics when combined with an actual blue LED chip. That is, as described above, the bins 4 and 5 relatively satisfy the target color coordinate region, but some of the bins 6 and 7 are adjacent to the boundary of the target color coordinates or exhibit yellowish yellow shift. In order to mitigate this deviation, in order to precisely control the final white light, a combination that can satisfy the target color gamut of the final white light was found by combining the unit fluorescent film of each bin with a blue LED chip having different optical characteristics. Here, optical characteristics of the blue LED chip were classified into light output along with peak wavelength.

Unit Fluorescent Film Group bin 4 bin 5 bin 6 bin 7 bin 8 Blue LED Chip Peak Wavelength 455 nm 455 nm 453 nm 451-453 nm 447-450 Blue LED Chip Light Output 140 mW 143mW 143mW 144-145 nm 144-145 nm

In the case of the bin 5, as shown in Fig. 8, the target color coordinate region is satisfied by the blue LED chip (peak wavelength: 455 nm, light output: 143 mW), but in the case of the bin 4, it is somewhat adjacent to the blue side boundary. The light output of the blue LED chip was slightly lowered to satisfy the target color coordinate region. In addition, bins 5 and 6, which showed slightly yellow shifts, were combined with blue LED chips with slightly lower peak wavelengths and higher light output, while bins 9, which had the highest deviation, combined with LED chips with the highest peak wavelength and light output conditions. It was.

As a result, as shown in Fig. 9, the unit fluorescent film having a broadly different color distribution, such as bins 4 to 8, almost corresponds to the target color coordinate region, thereby greatly improving the dispersion and maximizing the yield of the light emitting device providing the desired white light. The result has been possible.

In this way, not only a plurality of unit fluorescent films obtained from a plurality of phosphor sheets obtained in a single process, but also all color deviations appearing in a plurality of unit fluorescent films obtained from one phosphor sheet can be considered, and LED devices having suitable optical characteristics Combined with this, precise color control is possible, and as a result, a great effect of color dispersion improvement can be expected.

The present invention is not limited to the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

Claims (4)

A reference light source emitting a beam having a predetermined wavelength;
A beam adjusting optical system for guiding a beam emitted from the reference light source to be irradiated to a fluorescent film to be measured, and adjusting a beam spot size to have a size smaller than an area of a unit fluorescent film to be applied to individual LED elements at a measurement position of the fluorescent film;
A detector configured to detect light converted from the fluorescent film by irradiation of the beam; And
It includes a light conversion characteristic measuring unit for measuring the light conversion characteristics of the detected light,
The fluorescent film to be measured is a fluorescent film measuring apparatus, characterized in that the phosphor sheet divided into a plurality of unit fluorescent film or the unit fluorescent film separated from the phosphor sheet.
The method of claim 1,
The detector is located on the opposite side of the surface to which the beam is irradiated based on the fluorescent film measuring apparatus.
The method of claim 1,
The detection unit is a fluorescent film measuring apparatus, characterized in that located on the surface on which the beam is irradiated with respect to the fluorescent film.
The method of claim 1,
The reference light source is a fluorescent film measuring apparatus, characterized in that the ultraviolet or blue light source.

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