US20160060073A1

US20160060073A1 - Open reel

Info

Publication number: US20160060073A1
Application number: US14/783,517
Authority: US
Inventors: Toshio Hata; Masahiro Konishi
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2013-04-15
Filing date: 2014-03-24
Publication date: 2016-03-03
Also published as: JP6092372B2; CN105164824B; JPWO2014171268A1; WO2014171268A1; CN105164824A

Abstract

An open reel (1) according to the present invention includes a reel (30) and a phosphor-containing resin (20) in the form of a cord wound around the reel (30).

Description

TECHNICAL FIELD

The present invention relates to an open reel for storing/transporting a phosphor-containing resin in the form of a cord.

BACKGROUND ART

Hitherto, in a light-emitting device that uses an LED chip and a phosphor that emits fluorescent light when the phosphor is excited by light emission of the LED chip, the LED chip is sealed by a sealing resin, and the phosphor is dispersed in the sealing resin.
Here, phosphor whose size is in micrometers and that is used for sealing an LED chip needs to be rigorously stored for preventing, for example, adhesion and adsorption and scattering of moisture or the like. Therefore, hitherto, phosphor has been sealed in, for example, a storage bottle or a storage bag, has been placed in a moisture-proof box, and stored/transported.
Regarding such a sealing resin containing phosphor, Patent Literature 1 proposes formation of a phosphor-containing sealing resin in which phosphor is dispersed into the form of a sheet. According to Patent Literature 1, since it is possible to store/transport the phosphor while the phosphor is dispersed in resin, it is no longer necessary to, for example, rigorously store the phosphor in, for example, a storage box or a storage bottle.

CITATION LIST

Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2011-138831 (laid open on Jul. 17, 2011)

SUMMARY OF INVENTION

Technical Problem

However, the phosphor-containing sealing resin in the form of a sheet in Patent Literature 1 has large external dimensions. Therefore, the phosphor-containing sealing resin has poor portability and is difficult to carry.
In view of the aforementioned existing problems, it is an object of the present invention to provide an open reel in which handleability of a phosphor-containing resin is improved.

Solution to Problem

To solve the aforementioned problems, according to an aspect of the present invention, there is provided an open reel including a reel and a phosphor-containing resin in the form of a cord wound around the reel.

Advantageous Effects of Invention

According to the aspect of the present invention, it is possible to provide an open reel in which handleability of a phosphor-containing resin is improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a structure of an exterior of an open reel according to a first embodiment.

FIG. 2 is a graph conceptually showing viscosity characteristics of a silicone resin that is contained in a phosphor-containing resin in the form of a cord shown in FIG. 1.

FIGS. 3( a) to 3(d) are each a schematic view of an exemplary method for forming the phosphor-containing resin in the form of a cord shown in FIG. 1.

FIG. 4 is a schematic view of an exemplary method for winding the phosphor-containing resin in the form of a cord around a reel.

FIG. 5 is a perspective view of a structure of an exterior of a light-emitting device that has been produced by using the phosphor-containing resin in the form of a cord shown in FIG. 1.

FIGS. 6( a) to 6(d) are each a schematic view of the step for mounting a light-emitting element in a cavity among the steps for producing the light-emitting device shown in FIG. 5.

FIGS. 7( a) to 7(d) are each a schematic view of the step for sealing a light-emitting element with the phosphor-containing resin in the form of a cord among the steps for producing the light-emitting device shown in FIG. 5.

FIG. 8 is a schematic view of the step for dividing a multiple cavity circuit board among the steps for producing the light-emitting device shown in FIG. 5.

FIG. 9( a) is a perspective view of a modification of the open reel shown in FIG. 1, and FIG. 9( b) is a top perspective view thereof.

FIGS. 10( a) to 10(d) are each a schematic view of a forming method for processing a phosphor-containing resin in the form of a cord into the form of a sheet according to a second embodiment.

FIGS. 11( a) and 11(b) are each a sectional view of a method for producing light-emitting devices that use the phosphor-containing resin in the form of a sheet shown in FIG. 10( d).

FIG. 12 is a perspective view of a structure of an exterior of an open reel according to a third embodiment.

FIGS. 13( a) to 13(d) are each a schematic view of an exemplary method for forming a phosphor-containing resin in the form of a cord shown in FIG. 12.

FIG. 14 is a table showing changes in the viscosity and elasticity modulus of silicone resin depending upon whether or not a plasticizer shown in FIG. 13 is added.

DESCRIPTION OF EMBODIMENTS

First Embodiment

A description of an embodiment of an open reel according to the present invention on the basis of FIGS. 1 to 9 is as follows. The open reel according to the embodiment is used for sealing light-emitting elements, such as LED chips, that are mounted on light-emitting devices.

First, with reference to FIGS. 1 and 2, a structure of the open reel 1 according to the embodiment is described.
FIG. 1 is a perspective view of a structure of an exterior of the open reel 1 according to the embodiment. As shown in FIG. 1, the open reel 1 includes a phosphor-containing resin 20 and a reel 30.

(Phosphor-Containing Resin 20 in the Form of a Cord)

The phosphor-containing resin 20 in the form of a cord is used for sealing a light-emitting element that is mounted on a light-emitting device. More specifically, the phosphor-containing resin 20 in the form of a chord is formed by molding a thermoplastic resin in which phosphor is uniformly dispersed into the form of a cord, the phosphor being a wavelength converting substance.
As the phosphor, for example, an oxynitride phosphor (sialon phosphor etc.), a group III-V compound semiconductor nanoparticle phosphor (indium phosphide (InP) etc.), or a YAG phosphor may be used. However, the phosphor is not limited to the aforementioned substances. For example, a nitride phosphor and other types of phosphors (such as a KSF phosphor or a KTF phosphor) may be used.
Although, in the embodiment, phosphor is used as the wavelength converting substance, other types of wavelength converting substances may also be used. The wavelength converting substance may be any substance as long as it emits light of different wavelengths by converting the wavelength of light emitted from the light-emitting element.
The thermoplastic resin in which the phosphor is dispersed is not particularly limited in type as long as it is capable of being used for sealing a light-emitting element. However, it is desirable that the thermoplastic resin be thermoplastic at a temperature that is less than a predetermined cross-linking temperature, and is irreversibly cured at a temperature that is greater than or equal to the cross-linking temperature.
In the embodiment, silicone resin having the above-described characteristics is used as the thermoplastic resin. Silicone resin, in which a primary cross-link is formed, is obtained by removing an amount of solvent, such as BTX (benzene.toluene.xylene), for a semi-cured material, diluted with the solvent, by appropriately reducing the pressure. The silicone resin is thermoplastic at a temperature that is less than a predetermined secondary cross-linking temperature (cross-linking temperature) described below, and is irreversibly cured at a temperature that is greater than or equal to the secondary cross-linking temperature.
FIG. 2 is a graph conceptually showing viscosity characteristics of the silicone resin that is contained in the phosphor-containing resin 20 in the form of a cord shown in FIG. 1. As shown in FIG. 2, the viscosity of the silicone resin at room temperature T₀(approximately 25° C.) corresponds to a viscosity V₀(refer to P₀in the figure). The viscosity V₀allows the form of the phosphor-containing resin 20 in the form of a cord to be maintained.
When, from the room temperature T₀, the silicone resin is heated to a temperature near a secondary cross-linking temperature T₁(approximately 125° C.) at which a secondary cross-link is formed, the viscosity of the silicone resin is reduced, and the viscosity immediately before the secondary cross-linking temperature T₁becomes a viscosity V₁(refer to P₁in the figure). The viscosity V₁is the viscosity at which the silicone resin is melted such that it is flowable.
Changes in the silicone resin at a temperature region that is less than the secondary cross-linking temperature T₁from the room temperature T₀are heat-reversible. Therefore, when the temperature is reduced to the ordinary temperature T₀from a temperature near the secondary cross-linking temperature T₁, the viscosity of the silicone resin is increased, and returns to the original viscosity V₀at the room temperature T₀. Therefore, it is possible to repeatedly adjust the viscosity of the silicone resin from the viscosity V₀to the viscosity V₁by changing the temperature in the temperature region that is less than the secondary cross-linking temperature T₁from the room temperature T₀.
On the other hand, when the silicone resin is heated to a temperature that is greater than or equal to the secondary cross-linking temperature T₁, a secondary cross-link is formed in the silicone resin, as a result of which the silicone resin is cured. The viscosity of cured silicone resin cannot be actually defined. However, if the viscosity of cured silicone resin is conceptually defined as a viscosity V₂, the viscosity of the silicone resin is increased from the viscosity V₁to the viscosity V₂(refer to P₂in the figure). The viscosity V₂is conceptually defined as a viscosity at the secondary cross-linking temperature T₁when a secondary cross-link is formed in the silicone resin.
When, in the silicone resin after the secondary cross-linking, the temperature is increased or decreased from the secondary cross-linking temperature T₁, physical properties (such as the viscosity and the elasticity modulus) at the secondary cross-linking temperature T₁(polymeric properties) change. Compared to silicone resin before secondary cross-linking, the viscosity and the elasticity modulus become relatively high (at P₃in the figure, for convenience sake, the viscosity V₂is shown as being maintained).
The term “secondary cross-linking” refers to further curing resulting from, for example, a cross-linking reaction by a reactive catalyst differing from that when a synthesis is performed, and corresponds to a state in which irreversible viscosity changes do not occur depending on temperature as mentioned above.
In the phosphor-containing resin 20 in the form of a cord, in accordance with the optical characteristics required for light-emitting devices, various types of phosphors are included and the densities (percentage contents) of the phosphors are adjusted. If the silicone resin is used and it is in a state prior to secondary cross-linking, it is possible to repeatedly adjust the viscosity thereof. Therefore, as described below, it is possible to obtain a phosphor-containing resin 20 in the form of a cord in which the dispersed state of the phosphor is uniform.
As the silicone resin contained in the phosphor-containing resin 20 in the form of a cord, for example, it is possible to suitably use “TX-2506 series” (tradename; Dow Corning Corporation).
According to the phosphor-containing resin 20 in the form of a cord, it is possible to store the phosphor while the phosphor is dispersed in the silicone resin. Therefore, it is possible to overcome the existing problem that phosphor-containing resin is difficult to handle when powder phosphor and liquid resin are separately stored.

(Reel 30)

The reel 30 is provided for winding the phosphor-containing resin 20 in the form of a cord therearound. The reel 30 includes a core portion and two flange portions that are provided on respective ends of the core portion and that are parallel to each other. The phosphor-containing resin 20 in the form of a cord is wound around the core portion of the reel 30. The reel 30 is formed of various materials, such as a metal or a resin.
Accordingly, in the open reel 1, by winding the phosphor-containing resin 20 in the form a cord around the reel 30, it is possible to compactly store the phosphor-containing resin 20. Therefore, it is possible to easily carry the phosphor-containing resin 20 by increasing the portability thereof.
In addition, in the opening reel 1, by cutting to a desired length the phosphor-containing resin 20 in the form of a cord wound around the reel 30, it is possible to easily obtain a required quantity of phosphor-containing resin 20.
By forming the phosphor-containing resin 20 in the form a cord, the tensile strength of the phosphor-containing resin 20 is increased. Therefore, the phosphor-containing resin 20 in the form of a cord is less likely to be torn apart, as a result of which the phosphor-containing resin 20 can be easily wound around the reel 30.
The diameter of the phosphor-containing resin 20 in the form a cord is suitably selectable. For example, in accordance with the mode of use of the phosphor-containing resin 20 in the form a cord, the diameter of the phosphor-containing resin 20 in the form a cord may be on the order of a few hundred μm to a few tens of mm.

Next, a method for producing the open reel 1 is described with reference to FIGS. 3 and 4.
FIGS. 3( a) to 3(d) are each a schematic view of an exemplary method for forming the phosphor-containing resin 20 in the form of a cord shown in FIG. 1. As shown in FIG. 3(a), first, powder of a phosphor 22 and powder of a silicone resin 21 in which a primary cross-link has been formed are subjected to dry mixing until the state of mixture becomes uniform, to obtain a powder mixture 24.
Next, as shown in FIG. 3( b), the powder mixture 24 is introduced into a double screw extruder 37, and is kneaded while being heated and melted at a temperature that is less than the secondary cross-linking temperature T₁.
The double screw extruder 37 includes two screws 37 a that are provided parallel to each other in a cylinder. By rotating the two screws 37 a in opposite directions, it is possible to knead the powder mixture 24 while melting the silicone resin 21 by heating.
By the heating and the kneading, as shown in FIG. 3( c), the powder mixture 24 becomes a kneaded mixture 25 in which the phosphor 22 is uniformly dispersed in the melted silicone resin 21. By extruding the kneaded mixture 25 from a discharge opening 37 b of the double screw extruder 37 so as to have the form of a cord, as shown in FIG. 3( d), it is possible to form a phosphor-containing resin 20 in the form of a cord in which the phosphor 22 is uniformly dispersed in the silicone resin 21. By winding the phosphor-containing resin 20 in the form a cord around the core portion of the reel 30, it is possible to produce the open reel 1.
FIG. 4 is a schematic view of an exemplary method for winding the phosphor-containing resin 20 in the form of a cord around the reel 30. As shown in FIG. 4, the phosphor-containing resin 20 in the form of a cord that has been extruded from the discharge opening 37 b of the double screw extruder 37 may be directly wound around the reel 30. In this case, the reel 30 is provided so as to be rotatable in the direction of the arrow in FIG. 4 by rotation driving means using, for example, a motor.
At this time, it is desirable that the rotation speed of the reel 30 be controlled such that the length (quantity) of the phosphor-containing resin 20 in the form of a cord wound around the reel 30 per unit time be equal to or slightly less than the length (quantity) of the phosphor-containing resin 20 in the form of a cord that is extruded from the discharge opening 37 b per unit time. Alternatively, it is desirable that the rotation speed of the screws 37 a be controlled such that the length (quantity) of the phosphor-containing resin 20 in the form of a cord that is extruded from the discharge opening 37 b per unit time be equal to or slightly greater than the length (quantity) of the phosphor-containing resin 20 in the form of a cord that is wound around the reel 30 per unit time. This makes it possible to automatically wind the phosphor-containing resin 20 in the form of a cord around the reel 30 while reducing the tearing apart of the phosphor-containing resin 20 in the form of a cord.
According to the open reel 1 that has been produced in this way, by cutting the phosphor-containing resin 20 in the form of a cord into portions having the same length, it is possible to easily obtain a plurality of phosphor-containing resins 20 having the same phosphor content. Therefore, by sealing light-emitting elements by using these phosphor-containing resins 20, it is possible to equalize the phosphor contents of the light-emitting devices and to reduce variations in chroma.
By forming the phosphor-containing resin 20 in the form of a cord, for example, compared to a bulk type, it is possible to increase the melting efficiency of the silicone resin 21 during heating.
Therefore, by heating and melting the phosphor-containing resin 20 in the form of a cord at a temperature that is less than the secondary cross-linking temperature T₁such that the phosphor 22 does not precipitate, it is possible to easily process the phosphor-containing resin 20 in the form of a cord to a desired shape while maintaining the phosphor 22 in a state in which it is uniformly dispersed in the silicone resin 21.
Although, in the embodiment, the double screw extruder 37 including the two screws 37 a is used, a single screw extruder including one screw 37 a may be used instead of the double screw extruder 37. Alternatively, instead of the double screw extruder 37, a multiple screw extruder including three or more screws 37 a may be used. This makes it possible to increase kneading efficiency of the powder mixture 24 and the extrusion efficiency of the kneaded mixture 25. The number of discharge openings 37 b of these extruders and the dimensions and shapes of the discharge openings 37 b of these extruders are not particularly limited to certain values or shapes, and are suitably changeable if necessary. This makes it possible to easily change, for example, the diameter of the phosphor-containing resin 20 in the form of a cord that is formed. For example, the diameter of the discharge opening 37 b of the extruder may be on the order of a few hundred μm to a few tens of mm in accordance with the thickness (diameter) of the phosphor-containing resin 20 in the form of a cord that is formed.
Although, in the embodiment, the phosphor-containing resin 20 in the form of a cord is formed by using the double screw extruder 37, the phosphor-containing resin 20 in the form of a cord may be formed by using other methods.

Next, with reference to FIGS. 5 to 8, a method for producing light-emitting devices that use the phosphor-containing resin 20 in the form of a cord is described.
FIG. 5 is a perspective view of a structure of an exterior of a light-emitting device 40 that is produced by using the phosphor-containing resin 20 in the form of a cord. As shown in FIG. 5, the light-emitting device 40 is one in which a rectangular cavity 12 that opens upward is formed in a circuit board 11 which is a rectangular parallelepiped MID (molded interconnection device) having a side length on the order of 1 mm. In other words, the cavity 12 is a recessed portion formed in a top surface of the circuit board 11. The light-emitting element 13, such as an LED chip, is mounted in the cavity 12.
A lower surface of the light-emitting element 13 is connected to a mount wiring pattern 14, which is provided on a bottom portion of the cavity 12, by a conductive adhesive 15 (die bonding).
A connection wiring pattern 16 that is provided at the bottom portion of the cavity 12 is connected to an upper surface of the light-emitting element 13 by a conductive wire 17 formed of a metallic wire or the like (wire bonding).
The interior of the cavity 12 of the circuit board 11 is sealed by the phosphor-containing resin 20.
An inner surface defining the cavity 12 of the circuit board 11 may function as a reflector. This makes it possible to increase the efficiency with which light is used at the light-emitting device 40. The method for mounting the light-emitting element 13 on the circuit board 11 is not particularly limited to certain methods. The light-emitting element 13 may be mounted on the circuit board 11 by, for example, a flip chip method instead of the wire bonding method.
FIGS. 6( a) to 6(d) are each a schematic view of the step for mounting a light-emitting element 13 in a cavity 12 among the steps for producing the light-emitting device 40 shown in FIG. 5.
In producing light-emitting devices 40, a multiple cavity circuit board 10 in which multiple cavities 12 are formed in a matrix in a vertical direction and a horizontal direction is used. By using the multiple cavity circuit board 10, it is possible to produce multiple light-emitting devices 40 at the same time. For example, the multiple cavity circuit board 10 has a thickness of 1 mm, and each cavity 12 has a depth of 0.6 mm.
First, as shown in FIG. 6( a), a mount wiring pattern 14 and a connection wiring pattern 16 are provided side by side on a bottom portion of each cavity 12.
Next, as shown in FIG. 6( b), a conductive adhesive 15 is applied to the mount wiring pattern 14 provided on the bottom portion of each cavity 12.
Next, as shown in FIG. 6( c), each light-emitting element 13 is die-bonded to the conductor adhesive 15 applied to the corresponding mount wiring pattern 14. Then, as shown in FIG. 6( d), an upper surface of each light-emitting element 13 and its corresponding connection wiring pattern 16 provided on the bottom portion of the corresponding cavity 12 are wire-bonded by a corresponding conductive wire 17 formed of a metallic wire or the like.
After mounting the light-emitting elements 13 in the respective cavities 12 of the multiple cavity circuit board 10 by die-bonding and wire-bonding the light-emitting elements 13, each cavity 12 is sealed by a phosphor-containing resin 20.
FIGS. 7( a) to 7(d) are each a schematic view of the step for sealing a light-emitting element 13 with the phosphor-containing resin 20 in the form of a cord among the steps for producing the light-emitting device 40 shown in FIG. 5.
As shown in FIG. 7( a), the multiple cavity circuit board 10 on which the light-emitting elements 13 are mounted is placed on a heater plate 31, and phosphor-containing resins 20 having equal lengths formed by a cutting operation, are disposed in the respective cavities 12. The phosphor-containing resins 20 having equal lengths formed by the cutting operation have substantially the same phosphor content. Therefore, by sealing the light-emitting elements 13 by using these phosphor-containing resins 20, it is possible to equalize the phosphor contents of the light-emitting devices 40 and to reduce variations in chroma.
After the phosphor-containing resins 20 have been disposed in the respective cavities, as shown in FIG. 7( b), the heater plate 31 heats the phosphor-containing resins 20 at the secondary cross-linking temperature T₁(such as 125° C.), and melts the phosphor-containing resins 20.
By this, as shown in FIG. 7( c), the cavities 12 are filled with the respective phosphor-containing resins 20, and a secondary cross-link is formed in a portion of each silicone resin 21, as a result of which curing is started. At this time, each phosphor-containing resin 20 in the corresponding cavity 13 is cured from a side of the bottom portion of its corresponding cavity 12 by the heater plate 31. Therefore, stress resulting from curing and contraction of the phosphor-containing resins 20 can be distributed to top portions of the phosphor-containing resins 20, that is, at an opening portion side of each cavity 12. Therefore, it is possible to suppress the occurrence of, for example, cracks and to increase the reliability of each light-emitting device 40.
Then, by heating the multiple cavity circuit board 10 to a temperature that is greater than or equal to the secondary cross-linking temperature T₁(for example, in a range of 125° C. to 170° C.) in an oven or the like, each silicone resin 21 is completely cured. Thereafter, the multiple cavity circuit board 10 is taken out from the oven or the like, to reduce the temperature to the room temperature T₀.
FIG. 8 is a schematic view of the step for dividing the multiple cavity circuit board 10 among the steps for producing the light-emitting device 40 shown in FIG. 5. As shown in FIG. 8, when the light-emitting elements 13 that are mounted on the respective cavities 20 are sealed by the respective phosphor-containing resins 20 in which a second cross-link is formed, the multiple cavity circuit board 10 is divided at each cavity 12. This makes it possible to produce a plurality of light-emitting devices 40 having uniform phosphor contents at the same time.
The chroma distribution ranges of the light-emitting devices 40 that have been produced in this way can satisfy a chromaticity control standard “2-step MacAdam ellipses”. The term “MacAdam ellipses” refers to a standard deviation of color discrimination variations from a specific center color on an xy chroma diagram such that levels in which chroma variations cannot be distinguished by the human eye can be realized.
In this way, by sealing the light-emitting elements 13 by using the phosphor-containing resins 20 in the form of a cord, it is possible equalize the phosphor contents of the light-emitting devices 40 and reduce chroma variations (chroma distribution ranges).
Although, in the embodiment, the light-emitting elements 13 mounted on the multiple cavity circuit board 10 are sealed by using the phosphor-containing resins 20 in the form of a cord, the present invention is not limited thereto. For example, the light-emitting elements 13 mounted on the divided circuit board 11 may be individually sealed by using the respective phosphor-containing resins 20 in the form of a cord.

Advantages of the First Embodiment

As described above, the open reel 1 according to the embodiment includes the reel 30 and the phosphor-containing resin 20 in the form of a cord wound around the reel 30.
In the open reel 1, by winding the phosphor-containing resin 20 in the form of a cord around the reel 30, it is possible to compactly store the phosphor-containing resin 20 in the form of a coil. Therefore, it is possible to easily carry the phosphor-containing resin 20 by increasing the portability thereof.
In addition, in the opening reel 1, by cutting to a desired length the phosphor-containing resin 20 in the form of a cord wound around the reel 30, it is possible to easily obtain a required quantity of phosphor-containing resin 20.
Therefore, according to the open reel 1, it is possible to improve handleability of the phosphor-containing resin 20.
Further, in the open reel 1, by cutting the phosphor-containing resin 20 in the form of a cord into portions having the same length, it is possible to easily obtain a plurality of phosphor-containing resins 20 having the same phosphor content. Therefore, by sealing the light-emitting elements by using these phosphor-containing resins 20, it is possible to equalize the phosphor contents of the light-emitting devices 40 and to reduce variations in chroma.
Consequently, according to the embodiment, it is possible to realize an open reel 1 in which the handleability of the phosphor-containing resins 20 is improved and the phosphor contents of the light-emitting devices 40 are equalized to allow variations in chroma to be reduced.
The phosphor-containing resin 20 in the form of a cord may have portions having different phosphor contents along an axial direction of the phosphor-containing resin 20. Accordingly, by sealing the light-emitting elements 13 by using the portions of the phosphor-containing resin 20 in the form of a cord having different phosphor contents, it is possible to, for example, produce light-emitting devices 40 having different light-emitting characteristics, such as one portion providing a daytime white color and another portion providing a lightbulb color. Alternatively, the phosphor-containing resin 20 in the form of a cord may have portions having different thixotropic properties in the axial direction of the phosphor-containing resin 20.
Two or more phosphor-containing resins 20 in the form of a cord having the same or different phosphor contents may be wound around the reel 30. This makes it possible to compactly store a plurality of phosphor-containing resins 20 in the form of a cord on one reel 30. Therefore, it is possible to easily, for example, store/transport the plurality of phosphor-containing resins 20.

Although, in the embodiment, the number of types of phosphors 22 contained in the phosphor-containing resin 20 in the form of a chord is one, two or more types of phosphors 22 having, for example, different emission colors, particle diameters, or specific gravities may be used. For example, it is possible to form a phosphor-containing resin 20 in the form of a cord containing a combination of a red light emitting phosphor and a green light emitting phosphor and seal a blue light emitting element 13. Alternatively, it is possible to form a phosphor-containing resin 20 in the form of a cord containing a combination of a blue light emitting phosphor and a yellow light emitting phosphor and seal a bluish purple light emitting element 13.
Even in these cases, powder of silicone resin 21 in which a primary cross-link is formed and powder of two or more types of phosphors 22 are subjected to dry mixing until the state of mixture becomes uniform, to obtain a powder mixture 24.
Thereafter, the powder mixture 24 is introduced into the double screw extruder 37, and is kneaded while being heated and melted at a temperature that is less than the secondary cross-linking temperature T₁.
By the heating and the kneading, the powder mixture 24 becomes a kneaded mixture 25 in which two or more types of phosphors 22 are uniformly dispersed in the melted silicone resin 21. By extruding the kneaded mixture 25 from the discharge opening 37 b of the double screw extruder 37, it is possible to form a phosphor-containing resin 20 in the form of a cord in which two or more types of phosphors 22 are uniformly dispersed in the silicone resin 21.
FIG. 9( a) is a perspective view of a modification of the open reel 1 shown in FIG. 1, and FIG. 9( b) is a top perspective view thereof. As shown in FIGS. 9( a) and 9(b), by changing the width of the reel 30, it is possible to form, for example, an open reel 1 a of a one-turn type. In this case, the length of the core portion of the reel 30 (that is, the interval between the flange portions) may be adjusted so as to be slightly larger than the diameter of a phosphor-containing resin 20 in the form of a cord. By the one-turn type, it is possible to prevent the phosphor-containing resin 20 in the form of a cord from becoming entangled and it becomes easy to control the remaining quantity of the phosphor-containing resin 20 in the form of a cord.

Second Embodiment

A description of an open reel according to another embodiment of the present invention on the basis of FIGS. 10 and 11 is as follows. For the sake of convenience, members having functions corresponding to the functions of those in the figures used to describe the above-described embodiment are given the same reference numerals and are not described.
This embodiment differs from the above-described embodiment in that light-emitting elements 13 are sealed by using a phosphor-containing resin 20 formed by processing a phosphor-containing resin 20 in the form of a cord into another shape.

First, with reference to FIG. 10, a forming method for processing a phosphor-containing resin 20 in the form of a cord into the form of a sheet is described.
FIGS. 10( a) to 10(d) are each a schematic view of a forming method for processing a phosphor-containing resin 20 in the form of a cord into the form of a sheet. A forming method for processing a phosphor-containing resin 20 in the form of a cord into the form of a sheet with a heat press is hereunder described.
First, as shown in FIG. 10( a), a phosphor-containing resin 20 in the form of a cord is disposed on a heater plate 31. Then, as shown in FIG. 10( b), the phosphor-containing resin 20 in the form of a cord is heated and melted at a temperature that is less than the secondary cross-linking temperature T₁, and the viscosity of silicone resin 21 is reduced by an amount that does not cause a phosphor 22 to precipitate.
Next, as shown in FIG. 10( c), the phosphor-containing resin 20 is pressed by a pressing plate 39 that has been heated to a temperature that is less than the secondary cross-linking temperature T₁. At this time, the thickness of the phosphor-containing resin 20 is adjusted by a spacer 38 that is disposed between the heater plate 31 and the pressing plate 39. Then, by reducing the temperature of the phosphor-containing resin 20 to the room temperature T₀, it is possible to obtain a phosphor-containing resin 20 in the form of a sheet in which the phosphor 22 is uniformly dispersed.
Accordingly, the phosphor-containing resin 20 in the form of a cord is such that the melting efficiency of the silicone resin 21 during heating is high; and, by heating and melting the phosphor-containing resin 20 in the form of a cord at a temperature that is less than the secondary cross-linking temperature T₁that does not cause the phosphor 22 to precipitate, it is possible to easily process the phosphor-containing resin 20 in the form of a cord into a desired form while maintaining the phosphor 22 in a state in which it is uniformly dispersed in the silicone resin 21.
Although, in this embodiment, the forming method for processing a phosphor-containing resin 20 in the form of a cord into the form of a sheet with a heat press is described, a phosphor-containing resin 20 in the form of a cord may be processed into the form of a sheet by using other methods, such as a T-die method.

Next, with reference to FIG. 11, a method for producing light-emitting devices 41 that use a phosphor-containing resin 20 in the form of a sheet is described.
FIGS. 11( a) and 11(b) are each a sectional view of the method for producing the light-emitting devices 41 that use the phosphor-containing resin 20 in the form of a sheet shown in FIG. 10( d). In producing the light-emitting devices 41, a planar circuit board 10 a having a flat surface is used and light-emitting elements 13 are mounted in a matrix in a vertical direction and a horizontal direction on the flat surface of the planar circuit board 10 a. By using such a planar circuit board 10 a, it is possible to produce multiple light-emitting devices 41 at the same time.
As shown in FIG. 11( a), the planar circuit board 10 a on which the plurality of light-emitting elements 13 are mounted in a matrix and the phosphor-containing resin 20 in the form of a sheet are stacked in this order on a heat plate 31. Then, by heating the planar circuit board 10 a by the heater plate 31, the phosphor-containing resin 20 in the form of a sheet is heated and melted at a temperature that is less than the secondary cross-linking temperature T₁. Then, the viscosity of a silicone resin 21 is reduced such that a phosphor 22 contained in the phosphor-containing resin 20 does not precipitate, and the phosphor-containing resin 20 in the form of a sheet is pressed in the direction of the planar circuit board 10 a by a pressing plate 39 heated at a temperature that is less than the secondary cross-linking temperature T₁. This makes it possible to closely contact the phosphor-containing resin 20 in the form of a sheet with top surfaces and side surfaces of the light-emitting elements 13.
Next, by, in this state, heating the phosphor-containing resin 20 in the form of a sheet to the secondary cross-linking temperature T₁by the heater plate 31, a secondary cross-link is formed in the silicone resin 21 and the silicone resin 21 is cured. Further, by heating the planar circuit board 10 a at a temperature that is greater than or equal to the secondary cross-linking temperature T₁in, for example, an oven, the silicone resin 21 is completely cured. Thereafter, the multiple cavity circuit board 10 is taken out, to reduce the temperature to the room temperature T₀.
Then, as shown in FIG. 11( b), by dividing the planar circuit board 10 a at each light-emitting element 13, it is possible to produce a plurality of light-emitting devices 41 whose phosphor contents are the same.
The method according to this embodiment for sealing light-emitting elements 13 by using a phosphor-containing resin 20 in the form of a sheet (sheet method) is applied when sealing the light-emitting elements 13 of light-emitting devices that are formed continuously with each other before a dividing operation. The method according to the first embodiment for sealing light-emitting elements 13 by using a phosphor-containing resin 20 in the form of a cord is applicable not only when sealing the light-emitting elements 13 of light-emitting devices before the dividing operation, but also when sealing the light-emitting elements 13 of the light-emitting devices after the dividing operation.

Advantages of the Second Embodiment

As described above, according to the phosphor-containing resin 20 in the form of a cord, for example, compared to a bulk type, it is possible to increase the melting efficiency of the silicone resin 21 during heating. Therefore, it is possible to easily process the phosphor-containing resin into a desired shape in accordance with use thereof. Consequently, by processing the phosphor-containing resin 20 in the form of a cord into the form of a sheet and sealing the light-emitting elements 13 by using the phosphor-containing resin 20 in the form of a sheet, it is possible to equalize the phosphor contents of the light-emitting devices 41.
Thus, according to this embodiment, it is possible to equalize the phosphor contents of the light-emitting devices 41 and to reduce variations in chroma.
In this embodiment, although a phosphor-containing resin 20 in the form of a cord is processed into the form of a sheet, the phosphor-containing resin 20 in the form of a cord may be processed into other desired shapes such as a granular shape.

Third Embodiment

A description of an open reel according to another embodiment of the present invention on the basis of FIGS. 12 and 14 is as follows. For the sake of convenience, members having functions corresponding to the functions of those in the figures used to describe the above-described first embodiments are given the same reference numerals and are not described.
This embodiment differs from the above-described embodiments in that a plasticizer is added when forming a phosphor-containing resin in the form of a cord.

First, with reference to FIG. 12, a structure of an open reel 101 according to this embodiment is described.
FIG. 12 is a perspective view of a structure of an exterior of the open reel 101 according to the third embodiment. As shown in FIG. 12, the open reel 101 includes a phosphor-containing resin 120 in the form of a cord and a reel 30.

(Phosphor-Containing Resin 120 in the Form of a Cord)

The phosphor-containing resin 120 in the form of a cord is used for sealing light-emitting elements 13 that are mounted on light-emitting devices. More specifically, the phosphor-containing resin 120 in the form of a cord is formed by forming a silicone resin 21 in which a phosphor 22 is uniformly dispersed into the form of a cord, the phosphor 22 being a wavelength converting substance. In forming the phosphor-containing resin 120 in the form of a cord, as described below, a plasticizer that reduces the elasticity modulus of the silicone resin 21 after secondary cross-linking is added to the phosphor-containing resin 120 in the form of a cord.

Next, with reference to FIG. 13, a method for forming the phosphor-containing resin 120 in the form of a cord is described.
FIGS. 13( a) to 13(d) are each a schematic view of an exemplary method for forming the phosphor-containing resin 120 in the form of a cord shown in FIG. 12.
As shown in FIG. 13( a), first, powder of a phosphor 22 and powder of a silicone resin 21 in which a primary cross-link is formed are subjected to dry mixing until the state of mixture becomes uniform, to obtain a powder mixture 24.
Next, as shown in FIG. 13( b), a plasticizer 23 that reduces the elasticity modulus of the silicone resin 21 after secondary cross-linking (secondarily reduces the viscosity) is added to the powder mixture 24. The plasticizer 23 is described in more detail later. Then, the powder mixture 24 to which the plasticizer 23 has been added is introduced into the double screw extruder 37, and is kneaded while being heated and melted at a temperature that is less than the secondary cross-linking temperature T₁.
By the heating and the kneading, as shown in FIG. 13( c), the powder mixture 24 becomes a kneaded mixture 125 in which the phosphor 22 is uniformly dispersed in the melted silicone resin 21. By extruding the kneaded mixture 125 from the discharge opening 37 b of the double screw extruder 37, as shown in FIG. 13( d), it is possible to form a phosphor-containing resin 120 in the form of a cord in which the phosphor 22 is uniformly dispersed in the silicone resin 21.

Next, with reference to FIG. 14, the plasticizer 23 that is added in forming the phosphor-containing resin 120 in the form of a cord is described in detail.
The silicone resin 21 in which a primary cross-link has been formed has a relatively high viscosity at the room temperature T₀, low meltability due to heating, and low tackiness (adhesiveness) and low wettability. Therefore, portions of the silicone resin 21 are not sufficiently fused together during heating, as a result of which many gaps are formed. When, in such a state, a secondary cross-link is formed in the silicone resin 21 and the silicone resin 21 is cured, cracks or the like tend to form in the phosphor-containing resin 120 that has sealed light-emitting elements 13. In order to suppress the occurrence of cracks, it is desirable that the elasticity modulus of the silicone resin 21 after the secondary cross-linking be reduced.
Therefore, in this embodiment, powder of a phosphor 22 and powder of a silicone resin 21 are subjected to dry mixing, and a small amount of plasticizer 23 in a liquid state that reduces the elasticity modulus of the silicone resin 21 after the secondary cross-linking is added to the obtained powder mixture 24.
The plasticizer 23 may be used for reducing the cross-link density of the silicone resin 21. This makes it possible to suitably reduce the elasticity modulus of the silicone resin 21 after the secondary cross-linking, and to suppress the occurrence of, for example, cracks in the phosphor-containing resin 120 that has sealed the light-emitting elements 13.
The plasticizer 23 may also be used for reducing the viscosity of the silicone resin 21 in which a first cross-link has been formed. This makes it easier to, for example, process the phosphor-containing resin 120 in the form of a cord, and the powder mixture 24 is provided with compatibility, so that it becomes easier for portions of the silicone resin 21 to be brought together without any gaps formed therein.
As such a plasticizer 23, for example, a plasticizer whose main component is silicone, such as a non-functional silicone oil or a mono-functional silicone oil, may be suitably used. Alternatively, a substance that reacts or does not react with matrix silicone may also be used. The plasticizer 23 may be suitably selected in accordance with the characteristics of the light-emitting devices.
FIG. 14 is a table showing changes in the viscosity and elasticity modulus of the silicone resin 21 depending upon whether or not the plasticizer 23 shown in FIG. 13 is added. FIG. 14 shows the viscosity of the silicone resin 21 prior to secondary cross-linking (state in which a primary cross-link has been formed), and the elasticity modulus of the silicone resin 21 after the secondary cross-linking.
As shown in FIG. 14, by adding (11 wt % of) the plasticizer 23 to the silicone resin 21, the viscosity of the silicone resin 21 prior to secondary cross-linking at 25° C. is reduced to approximately ⅓ of the original value. The viscosity of the silicone resin 21 prior to secondary cross-linking at 120° C. can be reduced to approximately 1/100 of the original value.
Although the value of the viscosity of the silicone resin 21 changes in accordance with the amount of plasticizer 23 that is added, the value is approximately 1×10⁴Pa·s to 1×10⁵Pa·s at 25° C., and is approximately 1×10²Pa·s to 1×10⁴Pa·s at 120° C. When the amount of plasticizer 23 that is added is expressed in terms of the weight ratio of the plasticizer 23 with respect to the silicone resin 21, it is desirably from 5 to 20 wt %; more desirably, from 8 to 15 wt %; and, even more desirably, approximately 11 wt %.
Further, by adding the plasticizer 23 to the silicone resin 21, it is possible to reduce the elasticity modulus of the silicone resin 21 after the secondary cross-linking at 25° C. from ˜5×10⁷Pa to ˜1×10⁷Pa. In addition, it is possible to reduce the elasticity modulus of the silicone resin 21 after the secondary cross-linking at 125° C. from ˜1×10⁷Pa to ˜2×10⁶Pa.
In this way, since, by adding the plasticizer 23, the viscosity of the silicone resin 21 prior to the secondary cross-linking can be reduced, it is possible to easily, for example, process the phosphor-containing resin 120 in the form of a cord in which a primary cross-link has been formed.
Further, by adding the plasticizer 23, the cross-link density of the silicone resin 21 is reduced, so that it is possible to reduce the elasticity modulus of the silicone resin 21 after the secondary cross-linking at 25° C. and at 125° C. This makes it possible to suppress the occurrence of, for example, cracks in the phosphor-containing resin 120 that has sealed the light-emitting elements 13.

Advantages of the Third Embodiment

As described above, the open reel 101 according to this embodiment contains the phosphor-containing resin 120 in the form of a cord to which the plasticizer 23 that reduces the elasticity modulus of the silicone resin 21 after the secondary cross-linking is added in the formation step.
By adding the plasticizer 23 that reduces the elasticity modulus of the silicone resin 21 after the secondary cross-linking, it is possible to suppress the occurrence of, for example, cracks in the phosphor-containing resin 120 that has sealed the light-emitting elements 13.
Therefore, according to this embodiment, it is possible to obtain a phosphor-containing resin 120 in the form of a cord that can increase the reliability of light-emitting devices.

Although, in this embodiment, the phosphor-containing resin 120 in the form of a cord is formed by using the double screw extruder 37 including the two screws 37 a, it is possible to use a batch system for uniformly kneading a fixed amount of the plasticizer 23 in a liquid state into the powder mixture 24. Although it is possible to use, for example, a batch-system kneader, in particular, it is desirable to use an internal-return high-speed shear stirring device.
More specifically, when an internal-return high-speed shear stirring device including one screw is used, the powder mixture 24 and the plasticizer 23 that are introduced into a cylinder from a rear end side of the screw are moved in the cylinder to a front end side of the screw. Then, shear force is applied to the powder mixture 24 between a front end of the screw and an inside wall of the cylinder, and stirring is performed. At this time, the powder mixture 24 in the cylinder is heated at a temperature that is less than the secondary cross-linking temperature T₁, and the rotation speed of the screw is maintained at a value from 2500 rpm to 3000 rpm. The powder mixture 24 and the plasticizer 23 that have been stirred pass through a return-portion path provided in the interior of the screw, and move to the rear end side of the screw.
When this circulation is repeated for a certain period, the powder mixture 24 and the plasticizer 23 are sufficiently stirred to form the kneaded mixture 125. Thereafter, by extruding the kneaded mixture 125 from a discharge opening of the cylinder such that the kneaded mixture 125 is formed in the form of a cord, it is possible to form the phosphor-containing resin 120 in the form of a cord in which the phosphor 22 is uniformly dispersed in the silicone resin 21.

Fourth Embodiment

As phosphors contained in the phosphor-containing resins 20 according to the above-described first and second embodiments and phosphor contained in the phosphor-containing resin 120 according to the third embodiment, complex fluoride phosphor activated by Mn⁴⁺ is selected in this embodiment. For example, the following substances may be used as the complex fluoride phosphor.

(1) A₂[MF₅]:Mn⁴⁺
(where A is selected from Li, Na, K, Rb, Cs, NH₄, and combinations thereof, and M is selected from Al, Ga, In, and combinations thereof)
(2) A₃[MF₆]:Mn⁴⁺
(where A is selected from Li, Na, K, Rb, Cs, NH₄, and combinations thereof, and M is selected from Al, Ga, In, and combinations thereof)
(3) Zn₂[MF₇]:Mn⁴⁺
(where M is selected from Al, Ga, In, and combinations thereof)
(4) A[In₂F₇]:Mn⁴⁺
(where A is selected from Li, Na, K, Rb, Cs, NH₄, and combinations thereof)
(5) A₂[MF₆]:Mn⁴⁺
(where A is selected from Li, Na, K, Rb, Cs, NH₄, and combinations thereof, and M is selected from Ge, Si, Sn, Ti, Zr, and combinations thereof)
(6) E[MF₆]:Mn⁴⁺
(where E is selected from Mg, Ca, Sr, Ba, Zn, and combinations thereof, and M is selected from Ge, Si, Sn, Ti, Zr, and combinations thereof)
(7) Ba_0.65Zr_0.35F_2.70:Mn⁴⁺
(8) A₃[ZrF₇]:Mn⁴⁺
(where A is selected from Li, Na, K, Rb, Cs, NH₄, and combinations thereof)

Advantages of the Fourth Embodiment

In the fourth embodiment, by, as described above, kneading the complex fluoride phosphor activated by Mn⁴⁺ into the silicone resin 21, it is possible to store the phosphor 22 for a long period of time without deterioration of the phosphor 22.
In particular, the complex fluoride phosphor contains fluorine, and dissolves in water (solubility on the order of 1%) and generates hydrofluoric acid (HF). Since the sucking of powder adversely affects the human body, it is necessary to be careful when handling powder.
By forming the phosphor-containing resins 20, 120 containing such a complex fluoride phosphor into the form of a cord and winding such phosphor-containing resins 20, 120 around the reel 30, it is possible to safely, for example, carry and handle such phosphor-containing resins 20, 120.
Therefore, according to the fourth embodiment, it is possible to, for example, safely store the phosphor-containing resins 20, 120 containing such a complex fluoride phosphor for a long period of time.

[Recapitulation]

According to a first aspect of the present invention, there is provided an open reel including a reel and a phosphor-containing resin in a form of a cord wound around the reel.
In the above-described structure, by winding the phosphor-containing resin in the form a cord around the reel, it is possible to compactly store the phosphor-containing resin. Therefore, it is possible to easily carry the phosphor-containing resin by increasing the portability thereof.
In addition, in the above-described structure, by cutting to a desired length the phosphor-containing resin in the form of a cord wound around the reel, it is possible to easily obtain a required quantity of phosphor-containing resin.
Therefore, according to the above-described structure, it is possible to realize an open reel in which handleability of a phosphor-containing resin is improved.
In an open reel according to a second aspect of the present invention based on the first aspect, it is desirable that the phosphor-containing resin be such that at least a phosphor is dispersed in a thermoplastic resin (silicone resin 21), and that the thermoplastic resin be thermoplastic at a temperature that is less than a predetermined cross-linking temperature (secondary cross-linking temperature T₁), and be irreversibly cured at a temperature that is greater than or equal to the cross-linking temperature.
In the above-described structure, the thermoplastic resin in which a phosphor is dispersed is thermoplastic at a temperature that is less than the predetermined cross-linking temperature, and is irreversibly cured at a temperature that is greater than or equal to the cross-linking temperature. Therefore, it is possible to repeatedly adjust the viscosity of the thermoplastic resin by changing the temperature in a temperature region that is less than the predetermined cross-linking temperature.
Therefore, when kneading the phosphor into the thermoplastic resin, the viscosity of the thermoplastic resin is controlled by an amount that does not cause the kneaded phosphor to precipitate, as a result of which it is possible to uniformly disperse the phosphor in the thermoplastic resin.
Therefore, according to the above-described structure, it is possible to provide a phosphor-containing resin in the form of a cord in which the dispersability of the phosphor is improved.
In an open reel according to a third aspect of the present invention based on the second aspect, the cross-linking temperature may be in a range of 120° C. to 170° C.
An open reel according to a fourth aspect of the present invention based on the second aspect or the third aspect, the thermoplastic resin may contain a solvent containing benzene, toluene, and xylene.
In an open reel according to a fifth aspect of the present invention based on any one of the first aspect to fourth aspect, it is desirable that the phosphor-containing resin have portions having different phosphor contents along an axial direction of the phosphor-containing resin.
In the above-described structure, the phosphor-containing resin in the form of a cord may have portions having different phosphor contents along the axial direction of the phosphor-containing resin. Therefore, by sealing each light emitting element by using the portions of the phosphor-containing resin having different phosphor contents, it is possible to produce light-emitting devices having different light-emitting characteristics.
Therefore, according to the above-described structure, it is possible to produce light-emitting devices having various light-emitting characteristics by using one phosphor-containing resin in the form of a cord.
In an open reel according to a sixth aspect of the present invention based on any one of the first aspect to the fourth aspect, it is desirable that two or more of the phosphor-containing resins having the same phosphor content or different phosphor contents be wound around the reel, the number of which is one.
In the above-described structure, since two or more phosphor-containing resins in the form of a cord are wound around the reel, it is possible to compactly store a plurality of phosphor-containing resins on one reel. Therefore, according to the above-described structure, it is possible to easily, for example, store/transport the plurality of phosphor-containing resins.
The present invention is not limited to the above-described embodiments. Various changes may be made within the scope of the claims. Embodiments that result from appropriate combinations of technical means disclosed in the different embodiments are also included within the technical scope of the present invention.
Although in each of the above-described embodiments, a phosphor-containing resin in the form of a cord is used for sealing light-emitting elements, the use of phosphor-containing resin in the form of a cord is not limited to sealing the light-emitting elements. It may be used for other purposes. For example, a phosphor-containing resin in the form of a cord may be used in an LED bulb when the phosphor-containing resin is applied to a globe of the LED bulb. By applying the phosphor-containing resin to the globe of the LED bulb, it is possible for the heat of the phosphor to escape from the globe. Therefore, when the phosphor undergoes excitation, it is converted into heat and light, the heat is transmitted to the globe, and from the globe to an entire surface (in the air) or from the globe to a housing, so that excellent heat dissipation is provided.

[Supplement]

The open reel according to the present invention may be expressed as follows. That is, the open reel may be expressed as a reel-wind sealing resin according to the present invention including a reel and a phosphor-containing sealing resin in a form of a cord wound around the reel.
In the reel-wind sealing resin according to the present invention, it is desirable that the phosphor-containing sealing resin contain at least a thermoplastic resin and a phosphor, and the thermoplastic resin be thermoplastic at a temperature that is less than the predetermined cross-linking temperature and be irreversibly cured at a temperature that is greater than or equal to the cross-linking temperature.
In the reel-wind sealing resin according to the present invention, it is desirable that the cross-linking temperature be in a range of 120° C. to 170° C.
In the reel-wind sealing resin according to the present invention, it is desirable that the thermoplastic resin contain a solvent containing benzene, toluene, and xylene.
In the reel-wind sealing resin according to the present invention, it is desirable that the phosphor-containing sealing resin in the form of a cord be one whose phosphor content partly differs (or differs according to regions).
In the reel-wind sealing resin according to the present invention, it is desirable that two or more resins in the form of a cord having the same phosphor content or different phosphor contents be bundled together and wound around the reel.

INDUSTRIAL APPLICABILITY

The present invention is widely applicable to, for example, producing light-emitting devices that are used in, for example, display devices and lighting devices, backlights of displays or the like, traffic lights, and large outdoor displays and billboards that use LEDs or the like as light sources.

REFERENCE SIGNS LIST

- 1 open reel
- 1 a open reel
- 20 phosphor-containing resin
- 21 silicone resin (thermoplastic resin)
- 22 phosphor
- 23 plasticizer
- 24 powder mixture
- 25 kneaded mixture
- 30 reel
- 37 double screw extruder
- 37 a screw
- 37 b discharge opening
- 101 open reel
- 120 phosphor-containing resin
- 125 kneaded mixture
- T₁secondary cross-linking temperature (cross-linking temperature)

Claims

1. An open reel comprising:

a reel; and

a phosphor-containing resin in a form of a cord wound around the reel, wherein

the phosphor-containing resin being such that at least a phosphor is dispersed in a thermoplastic resin, and

the thermoplastic resin being a silicone resin which is thermoplastic at a temperature that is less than a predetermined cross-linking temperature, and which is irreversibly cured at a temperature that is greater than or equal to the cross-linking temperature.

2. (canceled)

3. The open reel according to claim 1, wherein the cross-linking temperature is in a range of 120° C. to 170° C.

4. The open reel according to claim 1, wherein the thermoplastic resin contains a solvent containing benzene, toluene, and xylene.

5. An open reel comprising:

a reel; and

a phosphor-containing resin in a form of a cord wound around the reel, wherein

the phosphor-containing resin having portions having different phosphor contents along an axial direction of the phosphor-containing resin.

6. The open reel according to claim 1, wherein two or more of the phosphor-containing resins having the same phosphor content or different phosphor contents are wound around the reel, the number of reels being one.