JP7319528B2 - Method for manufacturing light emitting device - Google Patents

Description

The present invention relates to a method for manufacturing a light emitting device.

2. Description of the Related Art Conventionally, light emitting devices using a combination of a semiconductor laser and a phosphor have been used as various light sources (for example, Patent Document 1, etc.).

Japanese Unexamined Patent Application Publication No. 2012-109400

However, when the temperature of a laser element, which is a semiconductor laser, increases due to heat generated by driving, the light emitted by the laser element shifts to the longer wavelength side, and when the temperature decreases, the light emitted by the laser element shifts to the shorter wavelength side. In contrast, the excitation peak of the excitation spectrum of phosphors does not fluctuate as much as the laser element, or does not substantially fluctuate even when the temperature changes. For this reason, the chromaticity of the mixed light obtained by combining the laser element and the phosphor tends to change depending on the temperature. Since the full width at half maximum of the emission spectrum of the laser light from a laser element is narrower than that from a light emitting diode (LED), the amount of change in the chromaticity of the mixed light due to temperature changes is greater than when the laser element is used as the light source. This is more pronounced when
An embodiment of the present invention has been made to solve the above problems, and is capable of reducing variations in the amount of chromaticity change due to temperature changes during driving. An object of the present invention is to manufacture a light-emitting device that emits mixed light.

The present application includes the following inventions.
preparing a plurality of semiconductor laser elements having oscillation wavelengths within the range of the same color, measuring the oscillation wavelength of each semiconductor laser element,
By preparing a plurality of phosphor-containing members containing the same phosphor and irradiating each phosphor-containing member with a light source for measurement having an oscillation wavelength within the range of the same color, A saturated output value or saturation, which is the output or drive current of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, by observing the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source or the drive current Determine the current value,
classifying the semiconductor laser elements into one of a plurality of wavelength groups including a short wavelength group on the short wavelength side and a long wavelength group on the long wavelength side according to the obtained oscillation wavelength;
According to the obtained saturation output value or saturation current value, the phosphor-containing member is classified into a low saturation group having a low saturation output value or a saturation current value and a low saturation group having a high saturation output value or a high saturation current value. Categorized into one of multiple saturation groups, including a highly saturated group,
When combining the semiconductor laser element and the phosphor-containing member, (a) combining the semiconductor laser element classified as the short wavelength group and the phosphor-containing member classified as the low saturation group, or (b) ) A method of manufacturing a light-emitting device, comprising combining a semiconductor laser element classified into the long wavelength group and a phosphor-containing member classified into the high saturation group.

preparing a plurality of semiconductor laser elements having oscillation wavelengths within the range of the same color, measuring the output and oscillation wavelength of each semiconductor laser element at a predetermined current value _Ax ,
By preparing a plurality of phosphor-containing members containing the same phosphor and irradiating each phosphor-containing member with a light source for measurement having an oscillation wavelength within the range of the same color, A saturated output value or saturation, which is the output or drive current of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, by observing the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source or the drive current Determine the current value,
According to the obtained oscillation wavelengths, the semiconductor laser elements are divided into a central wavelength group including a predetermined oscillation wavelength λ _X , a short wavelength group having a shorter wavelength than the central wavelength group, and a shorter wavelength group than the central wavelength group. classified into one of a plurality of wavelength groups including a long wavelength group on the long wavelength side, which is a long wavelength;
The semiconductor laser elements _of the central wavelength group are classified into a high-output subgroup and a low-output subgroup divided by a predetermined reference output _WX as a boundary, according to the obtained output at the predetermined current value AX. ,
According to the obtained saturation output value or saturation current value, the phosphor-containing member is classified into a low saturation group having a low saturation output value or a saturation current value and a low saturation group having a high saturation output value or a high saturation current value. Categorized into one of multiple saturation groups, including a highly saturated group,
When combining the semiconductor laser element and the phosphor-containing member, (d) the semiconductor laser element classified into the short wavelength group or the low output subgroup and the phosphor-containing member classified into the low saturation group. or (e) combining a semiconductor laser element classified into the long wavelength group or the high power subgroup and a phosphor-containing member classified into the high saturation group.

According to one embodiment of the present invention, a light-emitting device that emits mixed light by combining a laser element and a phosphor, capable of reducing variations in chromaticity change due to temperature changes during use, is manufactured. can be done.

4 is a flow chart showing a method for manufacturing the light emitting device according to Embodiment 1 of the present invention. 4 is a graph showing the relationship between the luminous flux of the phosphor-containing member and the driving current of the light source for measurement. 1 is a schematic cross-sectional view for explaining the structure of a light-emitting device manufactured according to the present invention; FIG. FIG. 4 is a schematic perspective view for explaining another structure of the light emitting device manufactured according to the present invention; It is a figure for demonstrating the manufacturing method of the light-emitting device of Embodiment 2 of this invention.

The embodiments shown below are examples for embodying the technical idea of the present invention, and are not intended to limit the present invention. Also, the sizes and positional relationships of members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, the same names and reference numerals basically indicate the same or homogeneous members, and overlapping descriptions will be omitted as appropriate.

<Embodiment 1>
A method for manufacturing a light emitting device according to Embodiment 1 of the present invention includes the following steps.
A step of preparing a plurality of semiconductor laser elements having oscillation wavelengths within the range of the same color (hereinafter sometimes referred to as "laser elements") and measuring the oscillation wavelength of each semiconductor laser element (S1).
By preparing a plurality of phosphor-containing members containing the same phosphor and irradiating each phosphor-containing member with a light source for measurement having an oscillation wavelength within the range of the same color, A saturated output value or saturation, which is the output or drive current of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, by observing the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source or the drive current A step of specifying a current value (S2).
A step of classifying the semiconductor laser elements into one of a plurality of wavelength groups including a short wavelength group on the short wavelength side and a long wavelength group on the long wavelength side according to the obtained oscillation wavelength (S3).
According to the obtained saturation output value or saturation current value, the phosphor-containing member is classified into a low saturation group having a low saturation output value or a saturation current value and a low saturation group having a high saturation output value or a high saturation current value. Classifying into one of a plurality of saturated groups including a highly saturated group (S4).
When combining the semiconductor laser element and the phosphor-containing member, (a) combining the semiconductor laser element classified as the short wavelength group and the phosphor-containing member classified as the low saturation group, or (b) ) A step of combining the semiconductor laser element classified as the long wavelength group and the phosphor-containing member classified as the high saturation group.
Thus, by performing the combination of (a) or (b) described above, a phosphor-containing member with a small chromaticity change amount and a laser element with a large chromaticity change amount are combined, or vice versa, that is, (2) combine a phosphor-containing member with a large amount of chromaticity change and a laser element with a small amount of chromaticity change; This makes it possible to reduce variations in the amount of chromaticity change when the light-emitting device is used, that is, when the temperature changes due to the driving of the laser element. As a result, a plurality of light-emitting devices having constant or nearly constant performance with small variations among the plurality of light-emitting devices can be obtained by a simple method of measuring the characteristics of each semiconductor laser element and phosphor-containing member in advance. can be manufactured easily, reliably, and with good reproducibility.

Such an effect was verified by the following experiments.
First, in a light-emitting device that obtains white light by combining a blue laser element that emits blue laser light and a YAG phosphor, an oscillation wavelength (peak wavelength) of the blue laser element and a phosphor-containing member before being incorporated into the light-emitting device A plurality of light emitting devices having slightly different saturation current values were prepared. The chromaticity during pulse driving and the chromaticity during continuous driving were measured for each of the plurality of light emitting devices, and the difference between the chromaticities was obtained. The reason for comparing the chromaticity during pulse driving and the chromaticity during continuous driving is that the temperature during driving of the light emitting device is higher during continuous driving than during pulse driving. The difference in chromaticity during continuous driving can be said to be the amount of change in chromaticity due to temperature rise.
Looking at the correlation between the oscillation wavelength and the saturation current value for such chromaticity change amount, there is a tendency that the shorter the oscillation wavelength before incorporation, the smaller the chromaticity change amount, and the lower the saturation current value before incorporation, the smaller the amount of chromaticity change. It was found that there was a tendency that the amount of change in chromaticity was large.
Regarding the former tendency, when the oscillation wavelength is shorter than the excitation peak of the excitation spectrum of the phosphor, the oscillation wavelength approaches the excitation peak of the excitation spectrum of the phosphor due to the lengthening of the oscillation wavelength due to the temperature rise. Conversely, when the oscillation wavelength is longer than the excitation peak of the excitation spectrum of the phosphor, the oscillation wavelength is lengthened by the temperature rise, and the oscillation wavelength moves away from the excitation peak of the excitation spectrum of the phosphor. can be explained from That is, although the luminous efficiency of the phosphor decreases due to the temperature rise, when the oscillation wavelength is shorter than the excitation peak of the excitation spectrum of the phosphor, the oscillation wavelength approaches the excitation peak of the excitation spectrum of the phosphor. It is thought that the influence of the decrease in the luminous efficiency of the phosphor when the laser element and the phosphor-containing member are combined is alleviated.
Regarding the latter tendency, a low saturation current value can be rephrased as a low temperature at which luminous efficiency begins to decline. This is thought to be due to
Therefore, a combination in which the amount of chromaticity change is averaged in a plurality of light emitting devices, such as a combination of a semiconductor laser element that tends to have a large amount of chromaticity change and a phosphor-containing member that tends to have a small amount of chromaticity change. By manufacturing a plurality of light-emitting devices, it is possible to reduce variations in the amount of chromaticity change in the plurality of light-emitting devices when the temperature changes.

(Preparation of laser element and measurement of its oscillation wavelength: S1)
First, as shown in S1 of FIG. 1, a plurality of laser elements are prepared, and the oscillation wavelength of each laser element is measured.
As the laser element to be prepared, a _nitride semiconductor, for example, an element having a laminated structure such as a semiconductor layer represented by the formula _{InxAlyGa1 -xyN} (0≤x, 0≤y, x+y≤1) is used. mentioned. A plurality of laser elements prepared in this embodiment have substantially the same layered structure of semiconductor layers (setting values such as composition of each semiconductor layer, layering order, film thickness, doping amount of impurities, etc.). is preferred. This is because different laminated structures of semiconductor layers have different temperature characteristics, and the degree of wavelength shift due to temperature varies. For example, when manufacturing a plurality of laser elements with similar setting values, the oscillation wavelength usually varies. Therefore, laser elements manufactured with similar setting values may be used.
The plurality of laser elements to be prepared are laser elements having oscillation wavelengths within the range of the same color. The same color range includes a range of wavelengths in the visible light region. Here, the range of the same color means light within a wavelength range that can be visually regarded as light of the same color. For example, blue light means light in the wavelength range of 435 nm to 480 nm, green light means light in the wavelength range of 500 nm to 560 nm, and red light means light in the wavelength range of 610 nm to 750 nm. means light. However, this wavelength range is an example, and any other wavelength range can be set according to the application. Also, the range of the same color can be a range manufactured with the intention of a laser device that oscillates at a specific wavelength. Such a range may be a range of ±20 nm of the specific wavelength, a range of ±10 nm of the specific wavelength, or a range of ±5 nm of the specific wavelength. From another point of view, the width of the range of the same color may be 40 nm or less, may be 20 nm or less, or may be 10 nm or less. A laser element that is combined with a YAG phosphor, which will be described later, includes a laser element that emits blue laser light, and the wavelength range thereof is 445 nm to 455 nm. Further, the oscillation wavelength here means the peak wavelength.
The full width at half maximum of the laser light can be, for example, 10 nm or less, and may be 5 nm or less.

Measurement of the oscillation wavelength of a laser element can be performed using a method known in the art, such as a spectroscope, so long as the environment is the same for each laser element. For example, the laser element can be set to an arbitrary current value (for example, 2.3 A) that is actually used above the threshold, and continuously driven at room temperature to measure the oscillation wavelength of the laser element. Note that the oscillation wavelength at the time when 500 ms (milliseconds) have passed since the current application is used as the numerical value of the oscillation wavelength used in subsequent steps.
The number of the plurality of laser elements here may be two or more, and may be, for example, several tens to several hundred.

(Classification by wavelength of laser element: S3)
Based on the results obtained by measuring the oscillation wavelengths of the laser elements described above, the laser elements are classified according to wavelength. The classification here includes, for example, classification into a plurality of wavelength groups including a short wavelength group on the short wavelength side and a long wavelength group on the long wavelength side. The group can be divided into a short wavelength group and a long wavelength group with the oscillation wavelength of the light source for measurement described later as a boundary. Alternatively, three or more groups including a central wavelength group including the oscillation wavelength of a light source for measurement described later, a short wavelength group having shorter wavelengths than the central wavelength group, and a long wavelength group having longer wavelengths than the central wavelength group. can be classified into In either form, each of these groups may be further divided into two or more short wavelength groups, middle wavelength groups and/or long wavelength groups within each group. In the grouping described above, the oscillation wavelength of the light source for measurement was used as a reference, but instead of this, the wavelength of the excitation peak of the excitation spectrum of the phosphor of the phosphor-containing member may be used. Alternatively, the oscillation wavelength of the measurement light source may substantially match the excitation peak wavelength of the phosphor of the phosphor-containing member. "Substantially matched" here includes an error of less than 1 nm. A laser element having the same oscillation wavelength as the oscillation wavelength at the boundary of each group is set so as to belong to one of two adjacent groups. For example, laser elements having the same oscillation wavelength as the oscillation wavelength at the boundary of each group are classified into the group with the shorter wavelength among the two adjacent groups.
Specifically, when the oscillation wavelength range of the prepared laser element is 445 nm to 455 nm, and the oscillation wavelength of the laser element in the light source for measurement described later is 450 nm, the short wavelength group is a group of 445 nm or more and 450 nm or less. , the long wavelength group can be bisected as a group greater than 450 nm and less than or equal to 455 nm. Further, when the range of the oscillation wavelength of the prepared laser element is 445 nm to 455 nm, and the oscillation wavelength of the laser element in the light source for measurement described later is 450 nm, the short wavelength group is a group of 445 nm or more and 448 nm or less, and the central wavelength is The groups can be divided into three groups, namely groups greater than 448 nm and less than or equal to 452 nm, and long wavelength groups as groups greater than 452 nm and less than or equal to 455 nm. In this way, the entire oscillation wavelength range can be divided into groups substantially evenly. Each group may be unequal. The difference between the upper limit value and the lower limit value of each group can be, for example, 2 nm to 10 nm. Further, in the above example, all of the plurality of prepared laser elements are divided into each group, but only some of the plurality of laser elements may be divided into each group. Preferably, all of the prepared laser elements are sorted into each group.

(Specification of saturation output value or saturation current value of phosphor-containing member: S2)
First, a plurality of phosphor-containing members are prepared. The phosphor-containing member prepared here is a member in which the phosphor contained therein is used to convert the wavelength of at least part of the laser light emitted from the laser element prepared above. Therefore, the phosphor used has an excitation peak in the excitation spectrum. In addition, the excitation spectrum of the phosphor may have a plurality of excitation peaks, but unless otherwise described, the term “excitation peak” in this specification refers to the excitation light among the plurality of excitation peaks, that is, the above It refers to the excitation peak closest to the wavelength of the laser light emitted from the prepared laser device.
The phosphor-containing member preferably contains one type of phosphor, but may contain a plurality of types of phosphors, and two or more types of phosphors may be included in one phosphor-containing member. good. When a plurality of types of phosphors are used, it is preferable to use the excitation peak of one phosphor having the strongest emission intensity with respect to the excitation light as a reference.
The phosphor-containing member preferably has an excitation spectrum having an excitation peak with a full width at half maximum of 110 nm or less. Here, the full width at half maximum of an excitation spectrum having an excitation peak means the width at half maximum from the excitation peak.

(Phosphor-containing member)
The phosphor-containing member may be composed of only the phosphor, or may be composed of the phosphor and a holder for holding the phosphor.
When the phosphor-containing member is formed of only the phosphor, the phosphor-containing member can have less scattering and higher transmittance than the phosphor-containing member containing the support.
When the phosphor-containing member includes a holder, the holder is preferably made of an inorganic material. As a result, it is possible to suppress deterioration, discoloration, etc. of the holder caused by the light emitted from the laser element. Moreover, the phosphor-containing member is preferably made of a material having good light resistance and heat resistance, which is less likely to deteriorate even if it is irradiated with high-power light. For example, those having a melting point of 1000°C to 3000°C are mentioned, and those having a melting point of 1300°C to 2500°C are preferable. Examples of inorganic materials include ceramics. Among them, alumina ceramics containing aluminum oxide are preferable because they have good translucency, good melting point and good thermal conductivity. When the phosphor-containing member is formed of a mixture of a phosphor and a holder such as ceramics, the proportion of the phosphor can be 1% by weight or more with respect to the total weight of the phosphor-containing member, It can be 10% by weight or more, and may be 50% by weight or more. The proportion of the phosphor with respect to the total weight of the phosphor-containing member can be, for example, 95% by weight or less, and may be 80% by weight or less. The ratio of the phosphor to the total weight of the phosphor-containing member can be adjusted as appropriate.

As the phosphor, one used in the relevant field can be used. The type of phosphor to be used can be selected in consideration of, for example, the wavelength of light emitted from laser elements to be combined, the color of light to be obtained, and the like. Specifically, cerium-activated yttrium aluminum garnet (YAG) phosphors, cerium-activated lutetium aluminum garnet (LAG) phosphors, europium- and/or chromium-activated nitrogen-containing aluminosilicates Calcium (CASN) phosphors and the like are included. Among them, it is preferable to use a YAG phosphor which is excellent in heat resistance. When a plurality of types of phosphors are combined, the color rendering properties and color reproducibility can be adjusted by using phosphors with different emission colors in a combination and compounding ratio suitable for a desired color tone. Moreover, a plurality of types of phosphors may be contained in a single layer structure, or different phosphors may be contained in different layers in a laminated structure.

Next, as shown in S2 of FIG. 1, the saturated output value or saturated current value of the prepared phosphor-containing member is specified. That is, in each phosphor-containing member, the phosphor-containing member is irradiated with a light source for measurement having an oscillation wavelength within the range of the same color, and the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source for measurement or the drive current is measured. Observe. Then, either the output of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, that is, the saturation output value, or the driving current of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, that is, the saturation current value. identify. Here, a semiconductor laser element is used as the measurement light source. As described above, the semiconductor laser element in the light source for measurement can be appropriately selected from the results obtained by measuring the oscillation wavelength of the laser element prepared for use in combination with the phosphor-containing member. For example, it has an oscillation wavelength within the range of the same color as the laser element prepared for combined use, and the center oscillation wavelength between the maximum and minimum oscillation wavelengths of the plurality of laser elements prepared for combined use. is preferred. In other words, the semiconductor laser element in the measurement light source preferably has an oscillation wavelength that represents the average value of the upper limit and the lower limit of the oscillation wavelengths of a plurality of laser elements in the same color range that are used in combination. Specifically, for example, when a plurality of prepared laser elements exhibit an oscillation wavelength in the range of 445 nm to 455 nm, the oscillation wavelength of the laser element in the light source for measurement is the maximum and minimum values of the measured oscillation wavelengths. It is preferably set to an intermediate value, eg 450 nm. Such a value facilitates appropriate combination with a phosphor-containing member, which will be described later. As a result, it is possible to reduce the variation in the amount of chromaticity change in each light emitting device when the light emitting device is used (when the temperature changes).

The phosphor-containing member is irradiated with laser light obtained by continuously driving the laser element in the light source for measurement at a current value higher than the rated drive current (for example, the current is gradually increased to a current value higher than the rated drive current). In this case, the luminous flux of light emitted from the phosphor-containing member gradually increases, and when thermal saturation is reached, the luminous flux decreases. Therefore, the saturated output value refers to the output value of the laser element in the measurement light source when the phosphor-containing member exhibits the maximum luminous flux immediately before the luminous flux decreases. The unit of saturation output value is represented by W (watt), for example. Further, the saturation current value refers to the driving current value of the laser element in the light source for measurement when the phosphor-containing member exhibits the maximum luminous flux just before the luminous flux decreases. A unit of the saturation current value is, for example, mA (milliampere). For example, as shown in FIG. 2, a light source for measurement consisting of a laser element with an oscillation wavelength of 450 nm is continuously driven while applying a current value higher than the rated drive current, several hundred mA to several thousand mA, as a drive current to emit light. When a phosphor-containing member made of alumina ceramics containing a YAG phosphor as a phosphor is irradiated with laser light by continuous driving, fluorescence is emitted until the drive current of the laser element of the light source for measurement exceeds 3000 mA. The luminous flux of light emitted from the body-containing member gradually increases. Then, after exceeding 3000 mA, the phosphor-containing member reaches thermal saturation, and the luminous flux begins to decrease immediately after that. Therefore, in FIG. 2, the saturation current value is approximately 3200 mA. The saturated output value at this time is 4.5W. In the case of continuously driving the laser device, the accuracy of classification can be improved by narrowing the width of the current value and gradually increasing it from the rated driving current. The range of increase here is from 10 mA to several hundred mA, for example, 100 mA.

(Classification by saturation output value or saturation current value of phosphor-containing member: S4)
The phosphor-containing members are classified based on the saturated power value or saturated current value obtained, respectively. Classification here includes, for example, a plurality of saturation groups including a low saturation group on the side of a low saturation output value or saturation current value and a high saturation group on the side of a high saturation output value or saturation current value. . The groups can be divided into a low saturation group and a high saturation group with a predetermined saturation output value or saturation current value as a boundary. Alternatively, it is divided into three or more groups including a central saturation group including a predetermined saturation output value or saturation current value, a low saturation group lower than the central saturation group, and a high saturation group higher than the central saturation group. may In either form, each of these groups may be further divided into two or more low saturation groups, middle saturation groups and/or high saturation groups within each group. A phosphor-containing member having the same saturated output value or saturated current value as the boundary saturated output value or saturated current value of each group is set so as to belong to one of two adjacent groups. For example, phosphor-containing members having the same saturation output value or saturation current value as the boundary of each group are classified into the group with the lower value among the two adjacent groups.

As described above, when the oscillation wavelength of the laser element in the light source for measurement is 450 nm, and the relationship between the luminous flux and the saturation current as shown in FIG. can be done. Such a value facilitates appropriate combination with a phosphor-containing member, which will be described later. As a result, it is possible to reduce variations in the amount of chromaticity change in individual light emitting devices when the light emitting devices are actually used (when the temperature changes). Such a predetermined value can be set to a current value that is about 25% to 10% smaller than the saturation current value. Also, when the predetermined value is the saturated output value, it can be set to 3.85 W, for example. Such a predetermined value may be set to an output value that is about 10% to 25% smaller than the saturated output value.
From another point of view, when the oscillation wavelength of the laser element in the light source for measurement is 450 nm and the relationship between the luminous flux and the saturation current is shown in FIG. can be set to Accordingly, the phosphor-containing member can be divided into three. Such a predetermined value can be set to a current value in the range of 25% to 10% of the saturation current value. Also, when the predetermined value is the saturated output value, it can be set to 3.7 W, for example. Such a predetermined value may be set to an output value in the range of 10% to 25% of the saturated output value. Each group into which the phosphor-containing members are classified may divide the entire area in which the measured saturation current values are distributed substantially evenly or unevenly. The difference between the upper and lower limits of each group can be, for example, 200mA to 500mA. Alternatively, only some of the prepared phosphor-containing members may be divided into each group. Preferably, all of the prepared phosphor-containing members are sorted into each group.

(Combination of laser element and phosphor-containing member: S5)
A semiconductor laser element and a phosphor-containing member are combined. Note that steps S1 to S4 described above can be executed in any order as long as they are performed in the order of steps S1 and S3 and in the order of steps S2 and S4. For example, the order of step S2, step S1, step S4, and step S3 can be mentioned. Then, the combination of the semiconductor laser element and the phosphor-containing member is performed as step S5 after performing the steps S1 to S4 described above.
The combination of the semiconductor laser element and the phosphor-containing member may be (a) a combination of a semiconductor laser element classified into the short wavelength group and a phosphor-containing member classified into the low saturation group, or (b) a long wavelength group. and a phosphor-containing member classified into the high saturation group. In other words, at least one of (a) and (b) may be combined, preferably both. In particular, when the semiconductor laser elements are classified into two groups and the phosphor-containing members are classified into two groups, it is more preferable to combine both (a) and (b).
The combination of (a) and/or (b) is a combination of a laser element with a small chromaticity change and a phosphor-containing member with a large chromaticity change, or a combination of a phosphor-containing member with a small chromaticity change. It means combining with a laser element having a large amount of chromaticity change. Such a combination makes it possible to reduce variation in the amount of chromaticity change when the light emitting device is actually used, that is, when the temperature of the phosphor-containing member changes, that is, variation in individual light emitting devices.
Further, as described above, when the laser elements and the phosphor-containing members are classified into three groups respectively, (a′) the semiconductor laser element classified into the shortest wavelength group and the phosphor-containing member classified into the lowest saturation group or (b′) a combination of a semiconductor laser element classified into the longest wavelength group and a phosphor-containing member classified into the highest saturation group, or (c′) a semiconductor laser classified into the central wavelength group. It preferably includes combining the element with a phosphor-containing member classified in the middle saturation group. By selecting such a combination, by combining a phosphor-containing member with a large amount of chromaticity change and a laser element with a small amount of chromaticity change, temperature changes during use of the light emitting device, that is, by driving the laser element, can be minimized. It is possible to reduce the variation in the amount of chromaticity change when this occurs. As a result, a plurality of light-emitting devices having constant or nearly constant performance with small variations among the plurality of light-emitting devices can be obtained by a simple method of measuring the characteristics of each semiconductor laser element and phosphor-containing member in advance. can be manufactured easily, reliably, and with good reproducibility.
The combination of the laser element and the phosphor-containing member may be a combination of one laser element and one phosphor-containing member, or a combination of a plurality of laser elements and one phosphor-containing member and one laser element. It may be a combination of an element and a plurality of phosphor-containing members. It is preferable to combine one phosphor-containing member with one laser element, and this can reduce variations in light-emitting devices that can be obtained more reliably.

By such a manufacturing method, it is possible to combine a specific laser element and a specific phosphor-containing member, and in each obtained light-emitting device, the variation in the amount of change in the chromaticity of fluorescence due to the temperature change of the laser element is reduced. can be made As a result, it is possible to manufacture a light-emitting device with stable characteristics capable of reducing the amount of change in chromaticity of emitted light with good reproducibility.

(light emitting device)
For example, as shown in FIG. 3, the manufactured light-emitting device 10 is configured with a phosphor-containing member 13 containing phosphor and a laser element 11 .
The phosphor-containing member 13 and the laser element 11 are hermetically sealed within the package member 15 . As a result, dust collection due to the laser beam emitted by the laser element can be suppressed. The package member 15 can be made of, for example, a metal containing copper, a copper alloy, an iron alloy, or the like, or ceramics containing aluminum nitride, aluminum oxide, or the like. It is preferable to use a material with good heat dissipation such as copper, copper alloy, aluminum nitride ceramics, etc. for the part of the package member 15 that can serve as a heat dissipation path, such as the part where the laser element 11 is mounted. The package member 15 is composed of, for example, a cap 17 and a base 18, which are joined using a metal adhesive or the like or by welding. The shape of the base 18 and/or the cap 17 that constitute the package member 15 includes, for example, various planar shapes such as a substantially circular shape, a substantially oval shape, and a substantially polygonal shape. A light extraction window for extracting light is provided on part or all of the upper surface of the package member 15 . The light extraction window can be, for example, rectangular in top view and made of glass or sapphire.
The phosphor-containing member 13 is a plate-like member, and is formed of a sintered body of a YAG phosphor (excitation peak: 450 nm, full width at half maximum of excitation spectrum having an excitation peak: 100 nm) and aluminum oxide. The YAG phosphor is contained in an amount of 50% by weight with respect to the total weight of the phosphor-containing member 13 . The phosphor-containing member 13 is arranged in such a direction that the surface of the phosphor-containing member 13 crosses the main path of the laser light emitted from the laser element 11 at an angle of 45 degrees. The phosphor-containing member 13 shown in FIG. 3 has a reflective structure in which the excitation light (laser light) incident surface and the light extraction surface are the same surface. In this case, the light reflecting member 14 may be arranged on the surface of the phosphor-containing member 13 opposite to the excitation light incident surface. The light reflecting member 14 reflects the light inside the phosphor-containing member 13 so that it is extracted from the excitation light incident surface, thereby improving the light extraction efficiency from the phosphor-containing member 13 . The phosphor-containing member may have a transmissive structure in which the excitation light incident surface and the light extraction surface are different surfaces.

The phosphor-containing member may be provided with a functional layer on the side of the excitation light incident surface and/or the light extraction surface, in contact or non-contact. For example, at least one of the excitation light incident surface and the light extraction surface of the phosphor-containing member may be provided with an antireflection film that suppresses reflection of laser light or the like, a short wavelength pass filter that transmits excitation light and reflects fluorescence, or a reflection of excitation light. However, a long wavelength pass filter or the like that transmits fluorescence may be arranged. The long-wave pass filter, for example, has a reflectance of less than 50% for excitation light and can be used to adjust the chromaticity by adjusting the intensity of the excitation light incident on the phosphor-containing member. Further, a light reflecting film and/or a light reflecting member may be provided in contact or non-contact on a surface other than the excitation light incident surface and the light extraction surface of the phosphor-containing member. For example, in the case of a reflective type, a light-reflecting film and/or a light-reflecting member can be arranged on the surface of the phosphor-containing member 13 opposite to the surface on which the excitation light is incident and the light is extracted. The light reflecting film and/or the light reflecting member preferably have a reflectance of 60% or more with respect to the irradiated laser light. Furthermore, a translucent member may be arranged on either side of the phosphor-containing member. Examples of translucent members include those that transmit 60% or more of laser light.
The laser element 11 is set to have a peak wavelength of 450 nm. The laser element 11 is mounted on a submount 16 whose main material is, for example, aluminum nitride. The submount 16 can improve heat dissipation by using a material with good heat dissipation as the main material. Main materials of the submount 16 include, for example, aluminum nitride and silicon carbide.
Such a light-emitting device 10 is particularly advantageous for applications with a wide operating temperature range, such as vehicle-mounted applications. For in-vehicle applications, for example, it is assumed to be used in an environment where the temperature changes from -several tens of degrees Celsius to about 100 degrees Celsius.

Further, as shown in FIG. 4, the light-emitting device 20 may include a laser element 11 and a cap (outer cap 27B) in which a phosphor-containing member 23 is arranged on the optical path of the laser element 11. good. 4 is a perspective view showing the light emitting device 20 with the inner cap 27A and the outer cap 27B cut along the optical path of the laser element 11. FIG.
As shown in FIG. 4, the light emitting device 20 includes a stem 28A, two lead terminals 28B penetrating the stem 28A, a submount 26 fixed to the side surface of a convex portion of the stem 28A, and a It has a fixed laser element 11 and a wire 29 electrically connecting the laser element 11 and each of the lead terminals 28B. The light emitting device 20 further has an inner cap 27A and an outer cap 27B. The inner cap 27A has an inner cap main body 271 fixed to the stem 28A and a lens 272 fixed to a through hole provided in the inner cap main body 271. As shown in FIG. The outer cap 27B has an outer cap main body 273, a lower pressing portion 274, an upper pressing portion 275, a light reflecting portion 276, and a phosphor-containing member 23. The phosphor-containing member 23 is fixed to the light reflecting portion 276 , and the light reflecting portion 276 is fixed by being sandwiched between the lower pressing portion 274 and the upper pressing portion 275 . As indicated by the dashed line in FIG. 4, the laser light emitted from the laser element 11 is collected by the lens 272 and focused in front of the phosphor-containing member 23 to enter the phosphor-containing member 23 . The laser element 11 is hermetically sealed by the stem 28A and the inner cap 27A. The inner cap 27A, outer cap 27B and stem 28A constitute a package member. In the light emitting device 20 shown in FIG. 4, the inner cap 27A and the outer cap 27B are separate members, but they may be integrally formed.

<Embodiment 2>
A method for manufacturing a light emitting device according to Embodiment 2 of the present invention includes the following steps.
A plurality of semiconductor laser elements having oscillation wavelengths within the same color range are prepared, and the output and oscillation wavelength of each semiconductor laser element at a predetermined current value A _X are measured.
By preparing a plurality of phosphor-containing members containing the same phosphor and irradiating each phosphor-containing member with a light source for measurement having an oscillation wavelength within the range of the same color, the output of the light source for measurement is obtained. Alternatively, the change in the luminous flux of the phosphor-containing member with respect to the change in the drive current is observed, and the output of the light source for measurement or the saturated output value or the saturated current value, which is the drive current, at which the luminous flux of the phosphor-containing member becomes the maximum value is specified.
According to the obtained oscillation wavelength, the semiconductor laser elements are divided into a central wavelength group including a predetermined oscillation wavelength λ _X , a short wavelength group having a shorter wavelength than the central wavelength group, and a longer wavelength group than the central wavelength group. It is classified into one of a plurality of wavelength groups including the long wavelength group on the long wavelength side.
The semiconductor laser elements of the central wavelength group are classified into a high output subgroup and a low output subgroup, which are divided with a predetermined reference output _Wx as a boundary, according to the obtained output at a predetermined current value _Ax .
The phosphor-containing members are divided into a low saturation group having a low saturation output value or a high saturation current value and a high saturation group having a high saturation output value or a high saturation current value according to the obtained saturation output value or saturation current value. Classify into one of several saturation groups, including
When combining a semiconductor laser element and a phosphor-containing member, (d) combining a semiconductor laser element classified into the short wavelength group or the low output subgroup with a phosphor-containing member classified into the low saturation group; (e) Combining a semiconductor laser element classified into the long wavelength group or high power subgroup and a phosphor-containing member classified into the high saturation group.
Also, the predetermined reference output W _X can be the output of the light source for measurement at a predetermined current value A _X .
The method for manufacturing the light-emitting device of Embodiment 2 will be described in detail below, but the same method, materials, etc. as in Embodiment 1 can be used except for those specifically described.

5A and 5B are diagrams for explaining the method for manufacturing the light emitting device of Embodiment 2. FIG. As shown in FIG. 5, the central wavelength group of laser elements can be further subdivided by a predetermined reference power _Wx . In FIG. 5, "center-high" indicates a high power subgroup within the central wavelength group, and "center-low" indicates a low power subgroup within the central wavelength group. The higher the output of the laser element, the greater the amount of heat generated by the combined phosphor-containing member, that is, the greater the amount of change in chromaticity. Therefore, as indicated by the pattern in FIG. 5, the high output subgroup is in the same category as the long wavelength group, which tends to have a large amount of chromaticity change, and the low output subgroup is in the same category as the short wavelength group. Then, each of them is combined with a phosphor-containing member. In this way, since the output (optical output) can also change the amount of chromaticity change, the output may be added to the criteria for grouping the laser elements. As in the first embodiment, laser elements having the same value as the boundary value of each group are set to belong to either of two adjacent groups. For example, laser elements having the same oscillation wavelength as the oscillation wavelength at the boundary of each group are classified into the group with the shorter wavelength among the two adjacent groups.
Since most of the plurality of laser elements are preferably grouped only by the oscillation wavelength, the difference between the upper limit and the lower limit of the central wavelength group in the second embodiment is the difference between the upper limit and the lower limit of the short wavelength group. , and preferably smaller than the difference between the upper and lower limits of the long wavelength group. The difference between the upper limit value and the lower limit value of the central wavelength group can be several nm, for example, 2 nm. When all of the plurality of semiconductor laser elements to be prepared are manufactured aiming at a predetermined oscillation wavelength _λX , the central wavelength group can be a group of wavelength bands including the predetermined oscillation wavelength _λX . can. For example, the central wavelength group can be the group of oscillation wavelengths λ _X ±1 nm. Also, the central wavelength group may be a group of wavelength bands including the excitation peak of the phosphor of the phosphor-containing member. The predetermined oscillation wavelength λ _X may substantially match the excitation peak wavelength of the phosphor of the phosphor-containing member. "Substantially matched" here includes an error of less than 1 nm.

Reference Signs List 10, 20 light emitting device 11 laser element 13, 23 phosphor-containing member 14 light reflecting member 15 package member 16, 26 submount 17 cap 18 base 27A inner cap 27B outer cap 271 inner cap main body 272 lens 273 outer cap main body 274 lower side Pressing portion 275 Upper pressing portion 276 Light reflecting portion 28A Stem 28B Lead terminal 29 Wire

Claims (10)

preparing a plurality of semiconductor laser elements having oscillation wavelengths within the range of the same color, measuring the oscillation wavelength of each semiconductor laser element,
A plurality of phosphor-containing members containing phosphors having excitation peak wavelengths within the range of the same color are prepared, and each phosphor-containing member contains a light source for measurement having an oscillation wavelength within the range of the same color. By irradiating the member, the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source for measurement or the change in the driving current is observed, and the output of the light source for measurement at which the luminous flux of the phosphor-containing member reaches the maximum value Or specify the saturation output value or saturation current value that is the drive current,
classifying the semiconductor laser elements into one of a plurality of wavelength groups including a short wavelength group on the short wavelength side and a long wavelength group on the long wavelength side according to the obtained oscillation wavelength;
According to the obtained saturation output value or saturation current value, the phosphor-containing member is classified into a low saturation group having a low saturation output value or a saturation current value and a low saturation group having a high saturation output value or a high saturation current value. Categorized into one of multiple saturation groups, including a highly saturated group,
When combining the semiconductor laser element and the phosphor-containing member, (a) combining the semiconductor laser element classified as the short wavelength group and the phosphor-containing member classified as the low saturation group, or (b) ) A method of manufacturing a light-emitting device, comprising combining a semiconductor laser element classified into the long wavelength group and a phosphor-containing member classified into the high saturation group. preparing a plurality of semiconductor laser elements having an oscillation wavelength within the range of blue, measuring the oscillation wavelength of each semiconductor laser element,
By preparing a plurality of phosphor-containing members containing the same phosphor and irradiating each phosphor-containing member with a light source for measurement having an oscillation wavelength within the blue range, A saturated output value or saturation, which is the output or drive current of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, by observing the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source or the drive current Determine the current value,
classifying the semiconductor laser elements into one of a plurality of wavelength groups including a short wavelength group on the short wavelength side and a long wavelength group on the long wavelength side according to the obtained oscillation wavelength;
According to the obtained saturation output value or saturation current value, the phosphor-containing member is classified into a low saturation group having a low saturation output value or a saturation current value and a low saturation group having a high saturation output value or a high saturation current value. Categorized into one of multiple saturation groups, including a highly saturated group,
When combining the semiconductor laser element and the phosphor-containing member, (a) combining the semiconductor laser element classified as the short wavelength group and the phosphor-containing member classified as the low saturation group, or (b) ) A method of manufacturing a light-emitting device, comprising combining a semiconductor laser element classified into the long wavelength group and a phosphor-containing member classified into the high saturation group to obtain white light. preparing a plurality of semiconductor laser elements having oscillation wavelengths within the range of the same color, measuring the oscillation wavelength of each semiconductor laser element,
By preparing a plurality of phosphor-containing members containing the same phosphor and irradiating each phosphor-containing member with a light source for measurement having an oscillation wavelength within the range of the same color, A saturated output value or saturation, which is the output or drive current of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, by observing the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source or the drive current Determine the current value,
classifying the semiconductor laser elements into one of a plurality of wavelength groups including a short wavelength group on the short wavelength side and a long wavelength group on the long wavelength side according to the obtained oscillation wavelength;
According to the obtained saturation output value or saturation current value, the phosphor-containing member is classified into a low saturation group having a low saturation output value or a saturation current value and a low saturation group having a high saturation output value or a high saturation current value. Categorized into one of multiple saturation groups, including a highly saturated group,
When combining the semiconductor laser element and the phosphor-containing member, (a) combining the semiconductor laser element classified as the short wavelength group and the phosphor-containing member classified as the low saturation group, or (b) ) combining the semiconductor laser element classified into the long wavelength group and the phosphor-containing member classified into the high saturation group, wherein the short wavelength group has an oscillation wavelength of excitation spectrum of the phosphor; A method for manufacturing a light-emitting device, comprising a semiconductor laser element having a wavelength shorter than the peak, and wherein the long wavelength group includes a semiconductor laser element having an oscillation wavelength longer than the excitation peak of the excitation spectrum of the phosphor. . The plurality of wavelength groups include a central wavelength group including the oscillation wavelength of the light source for measurement, the short wavelength group having shorter wavelengths than the central wavelength group, and the long wavelength group having longer wavelengths than the central wavelength group. 4. The method for manufacturing a light-emitting device according to claim 1, wherein the light-emitting device is divided into three or more groups including the group . 5. The method of manufacturing a light-emitting device according to claim 1, wherein the phosphor-containing member has an excitation spectrum having an excitation peak with a full width at half maximum of 110 nm or less . 6. The method of manufacturing a light-emitting device according to claim 5 , wherein the phosphor-containing member is a member containing a YAG phosphor. The manufacturing of the light-emitting device according to any one of claims 1 to 6 , wherein one semiconductor laser element and one phosphor-containing member are combined to manufacture a light-emitting device provided in one package. Method. preparing a plurality of semiconductor laser elements having oscillation wavelengths within the range of the same color, measuring the output and oscillation wavelength of each semiconductor laser element at a predetermined current value _Ax ,
A plurality of phosphor-containing members containing phosphors having excitation peak wavelengths within the range of the same color are prepared, and each phosphor-containing member contains a light source for measurement having an oscillation wavelength within the range of the same color. By irradiating the member, the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source for measurement or the change in the driving current is observed, and the output of the light source for measurement at which the luminous flux of the phosphor-containing member reaches the maximum value Or specify the saturation output value or saturation current value that is the drive current,
According to the obtained oscillation wavelengths, the semiconductor laser elements are divided into a central wavelength group including a predetermined oscillation wavelength λ _X , a short wavelength group having a shorter wavelength than the central wavelength group, and a shorter wavelength group than the central wavelength group. classified into one of a plurality of wavelength groups including a long wavelength group on the long wavelength side, which is a long wavelength;
The semiconductor laser elements _of the central wavelength group are classified into a high-output subgroup and a low-output subgroup divided by a predetermined reference output _WX as a boundary, according to the obtained output at the predetermined current value AX. ,
The phosphor-containing member, respectively, according to the obtained saturation output value or saturation current value,
classified into one of a plurality of saturation groups including a low saturation group on the side of the low saturation output value or the saturation current value and a high saturation group on the side of the high saturation output value or the saturation current value;
When combining the semiconductor laser element and the phosphor-containing member, (d) the semiconductor laser element classified into the short wavelength group or the low output subgroup and the phosphor-containing member classified into the low saturation group. or (e) combining a semiconductor laser element classified into the long wavelength group or the high power subgroup and a phosphor-containing member classified into the high saturation group. A plurality of semiconductor laser elements having oscillation wavelengths within the range of the same color are prepared, and a predetermined current value A of each semiconductor laser element is obtained. _X Measure the output and oscillation wavelength at
By preparing a plurality of phosphor-containing members containing the same phosphor and irradiating each phosphor-containing member with a light source for measurement having an oscillation wavelength within the range of the same color, A saturated output value or saturation, which is the output or drive current of the light source for measurement at which the luminous flux of the phosphor-containing member becomes the maximum value, by observing the change in the luminous flux of the phosphor-containing member with respect to the change in the output of the light source or the drive current Determine the current value,
Each of the semiconductor laser elements has a predetermined oscillation wavelength λ according to the obtained oscillation wavelength. _X , a short wavelength group having a shorter wavelength than the central wavelength group, and a long wavelength group having a longer wavelength than the central wavelength group. classify,
The semiconductor laser elements of the central wavelength group are operated at the obtained predetermined current value A. _X A predetermined reference output W _X into a high-power subgroup and a low-power subgroup separated by a boundary,
The phosphor-containing member, respectively, according to the obtained saturation output value or saturation current value,
classified into one of a plurality of saturation groups including a low saturation group on the side of the low saturation output value or the saturation current value and a high saturation group on the side of the high saturation output value or the saturation current value;
When combining the semiconductor laser element and the phosphor-containing member, (d) the semiconductor laser element classified into the short wavelength group or the low output subgroup and the phosphor-containing member classified into the low saturation group. or (e) combining a semiconductor laser element classified into the long wavelength group or the high power subgroup with a phosphor-containing member classified into the high saturation group, wherein the short wavelength group is and a semiconductor laser element having an oscillation wavelength shorter than the excitation peak of the excitation spectrum of the phosphor, and the long wavelength group includes semiconductor laser elements having an oscillation wavelength longer than the excitation peak of the excitation spectrum of the phosphor. A method of manufacturing a light emitting device including a laser element. 10. The method of manufacturing a light-emitting device according to claim 8 , wherein said predetermined reference output _WX is the output of said light source for measurement at said predetermined current value _AX .