JP3959284B2 - Optical semiconductor device for AF auxiliary light source - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical semiconductor device for an AF (Auto Focus) auxiliary light source .
[0002]
[Prior art]
2. Description of the Related Art In recent years, distance measuring devices used for DSC (Digital Still Camera) and the like enable focusing with higher accuracy by focusing simultaneously with AF illuminator irradiation in a dark place. Also, in order to reduce the red-eye phenomenon at night shooting (a phenomenon in which the eyes appear red when using the flash), the flash slow sync (which causes the flash to emit light at a slow shutter speed) is used. The applied AF assist light system such as “holographic AF” simultaneously realizes high-precision focusing and reduction of the red-eye phenomenon.
[0003]
Such an AF auxiliary light system uses an optical semiconductor device such as an LED and performs focusing by detecting the contour of the irradiated light. In recent years, the brightness of the optical semiconductor device has been increased, and the reach of the irradiated light has been greatly increased. Since it extends, it is possible to cope with focusing of a farther subject and to obtain high focus accuracy even in a low contrast such as a dark place.
[0004]
FIG. 10 shows an optical semiconductor device used in the AF auxiliary light system. A light-emitting element 1 made of a chip such as InGaAlP is placed on a pedestal 2 and sealed on the pedestal by a resin portion 3 using resin potting and transfer molding. The resin portion 3 has a lens effect, and is optically designed to converge the irradiation light 8 (diverging light) from the light emitting element 1 and improve the projection intensity. Then, it is attached to a holder (not shown), connected to a power source, a control system, etc. by leads (not shown) connected to the light emitting element 1 and mounted on the DSC.
[0005]
Irradiation light 8 from such an optical semiconductor device is used as an AF auxiliary light system that irradiates a subject 10 as shown in FIG. 11, performs focusing, and reduces the red-eye phenomenon.
[0006]
[Problems to be solved by the invention]
In such optical semiconductor devices, attempts have been made to incorporate optical simulation by the ray tracing method into the design. There was a problem that the irradiation intensity was uneven.
[0007]
For example, in the optical semiconductor device shown in FIG.
r: Lens (light exit surface) radius of curvature
d: Distance from top of lens (light emitting surface) to light emitting surface of light emitting element
n: Refractive index of optical component such as lens (resin part)
g: Light emission size of light emitting element (light emission size / 2)
Then,
r = 2.0mm
d = 4.75mm
n = 1.57
g = 0.15mm
As a result, there was no luminance unevenness in the optical simulation, and good characteristics were obtained. However, in the actually produced optical semiconductor device, the luminance Iv at a predetermined position is
Iv ≧ Ivmax / 2
Assuming that the range angle becomes α ′, the directivity angle (half-value angle) α indicating the divergence of the irradiation light shown in FIG.
α = 3 °
Although a narrow directivity package (semiconductor element) can be obtained, the projected light emission pattern has a strong irradiation intensity at the center portion and a weak donut shape at the periphery thereof, resulting in luminance unevenness.
[0008]
Also,
r = 1.3mm
d = 3.28 mm
n = 1.57
g = 0.15mm
As a result, there was no luminance unevenness in the optical simulation, and good characteristics were obtained. However, in the optical semiconductor device actually prototyped,
α = 4 °
Although a narrow directivity package can be obtained, the projected light emission pattern has a very weak irradiation intensity at the center and a strong donut shape around the periphery, resulting in uneven brightness. End up.
[0009]
As described above, the actual result is that the result of the optical simulation and the actual projection image do not coincide with each other, and the optimum value cannot be obtained by the simulation. Therefore, it was experimentally necessary to improve high convergence and brightness unevenness, but it was difficult to make prototypes and evaluate by changing all of the optical parameters, and the experimental accuracy would vary depending on the prototype accuracy. For this reason, fundamental improvements in characteristics have not been achieved. In fact, the occurrence of such luminance unevenness has been affected by a decrease in the focusing system.
[0010]
Further, in such an optical semiconductor device, the light emitting element 1 is mounted at the center of the pedestal 2 as shown in FIG. 12A by design, but as shown in FIG. 12B due to variations in mass production. When the mounting position of the light emitting element 1 is shifted and is off-centered, the irradiation light 8 is scraped near the exit (edge) of the holder 9 and the phenomenon of being broken occurs. Then, the projected image is deviated with respect to the target subject, deformed into a semicircle / crescent shape (although it is originally circular), and uneven brightness occurs, which similarly has an adverse effect on focusing. Therefore, as shown in FIG. 13, it is possible to add the lens 11 to further converge, but there is a problem that the cost increases because the number of parts increases.
[0011]
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical semiconductor device for an AF auxiliary light source that eliminates the disadvantages of conventional optical semiconductor devices, has high convergence, has less luminance unevenness, and can achieve high-precision focusing. Is.
[0012]
[Means for Solving the Invention]
An optical semiconductor device for an AF auxiliary light source according to an aspect of the present invention includes a light emitting element, a base on which the light emitting element is fixed, the light emitting element is covered on the base, and the irradiation light from the light emitting element is transmitted and converged. A resin portion to be connected, and a lead for connecting the light emitting element and an external circuit, and the resin portion includes a light emitting surface having a radius of curvature r, and the distance between the light emitting surface and the light emitting surface of the light emitting element is d. When the refractive index of the resin part is n and the light emission size of the light emitting element is g,
Σ = r / ((1-n) d + nr)
And the function (1 / r) gΣ ⁴
2 <Σ <5
2 <(1 / r) gΣ ⁴ <20
It is characterized by satisfying. Here, (1 / r) gΣ ⁴ is a function of Σ Considering the size of the emitting surface.
[0013]
In the optical semiconductor device for AF auxiliary light source according to one aspect of the present invention, the emission size g is
g ≦ 0.05mm
When,
2 <Σ <4
2 <(1 / r) gΣ ⁴ <12
It is characterized by satisfying.
[0014]
Furthermore, in the optical semiconductor device for an AF auxiliary light source of one embodiment of the present invention, a distance d between the light emitting surface and the light emitting surface of the light emitting element is:
d ≦ 3.5mm
When,
2 <(1 / r) gΣ ⁴ <10
It is characterized by satisfying.
[0015]
In the optical semiconductor device for an AF auxiliary light source of one embodiment of the present invention, a distance d between the light emission surface and the light emitting surface of the light emitting element is:
d ≦ 3.5mm
And the emission size g is
g ≦ 0.05mm
When,
2 <Σ <4
2 <(1 / r) gΣ ⁴ <6
It is characterized by satisfying.
[0016]
Further, in one aspect of the AF auxiliary light source for optical semiconductor device of the present invention, further contact with the end portion of the resin portion includes a holder which is formed in the light exit direction into the cylindrical side surfaces of said resin portion, said While being in contact with the light emitting surface and the pedestal, at least a part has a taper angle of 10 ° or more .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
As shown in the top view in FIG. 1A and the cross-sectional views in FIGS. 1B and 1C, the light-emitting element 1 made of a chip such as InGaAlP is placed on a pedestal 2 as in the prior art. 2 is resin-sealed using resin potting and transfer molding (resin portion 3). The light emitting element 1 is connected to the lead 5 and attached to a holder (not shown), connected to a power source, a control system, and the like, and mounted on the DSC.
[0018]
The light emitting element 1 emits light when a predetermined voltage is applied through the lead 5, and this irradiation light (diverging light) is converged by the lens effect on the light exit surface 4 of the resin portion 3 and irradiated to the subject. .
[0019]
In the optical semiconductor device for AF auxiliary light source configured as described above,
r = 1.5mm
d = 3.28 mm
n = 1.57
The optical design is performed so that Then, if g that affects the luminance variation is 0.15 mm, the convergence coefficient Σ and its function are
Σ = 3.090
(1 / r) gΣ ⁴ = 9.119
And is defined when d ≦ 3.5 mm.
2 <Σ <5
2 <(1 / r) gΣ ⁴ <10
Satisfy the condition of
[0020]
In the package 7 designed in this way, have line optical simulation of high accuracy by the ray tracing method, the ray trajectories simulated in FIG. 2, respectively, showing a light distribution characteristic in FIG. As a result, the directivity angle α is 3 ° from the ray trajectory, and it is possible to obtain a result that the luminance distribution is more favorable than the light distribution characteristic. On the other hand, even in the actual light emission pattern, luminance unevenness is not recognized and corresponds to the simulation result. Further, the thickness can be reduced to d = 3.28 mm.
(Embodiment 2)
As shown in FIG. 4, although the shape of the resin part 3 is different from that of the first embodiment , in the optical semiconductor device for AF auxiliary light source formed similarly,
r = 1.97mm
d = 4.28 mm
n = 1.57
The optical design is performed so that And if g is 0.15 mm, Σ and its function are
Σ = 3.304
(1 / r) gΣ ⁴ = 9.070
And
2 <Σ <5
2 <(1 / r) gΣ ⁴ <20
Satisfy the condition of
[0021]
The light emission pattern projected on the package designed in this manner has no luminance unevenness as in the first embodiment, and a directivity angle α of 4 ° provides a good characteristic. Further, the thickness can be reduced to d = 4.28 mm.
(Embodiment 3)
As shown in FIG. 1, in the optical semiconductor device for AF auxiliary light source designed in the same manner as in the first embodiment,
When the size of the light emitting element (g: light emitting size / 2) is 0.05 mm, the convergence coefficient and its function are:
Σ = 3.090
(1 / r) gΣ ⁴ = 3.040
And is defined when g ≦ 0.05 and d ≦ 3.5 mm.
2 <Σ <4
2 <(1 / r) gΣ ⁴ <6
Satisfy the condition of
[0022]
The light emission pattern projected on the package designed in this way has no luminance unevenness as in the first embodiment, and the directivity angle α is 3 °, which is a good characteristic. In addition, the thickness can be reduced to d = 3.28 mm, and the light emission size of the light emitting element is set to g = 0.05 mm, thereby suppressing luminance unevenness caused by the reduction in size and improving the irradiation intensity. Can be planned.
[0023]
As shown in the embodiment 1-3, a function of Σ and Σ a (1 / r) gΣ ⁴ by a predetermined range, it can be seen that good characteristics can be obtained. In FIG. 5, when d = 4.28 mm , g = 0.05 mm , and 0.15 mm (chip sizes are □ 0.1 mm and 0.3 mm , respectively), the directivity angle α, the luminance unevenness δIv, and the convergence coefficient FIG. 6 shows the relationship with Σ, FIG. 7 also shows the relationship with the function (1 / r) gΣ ⁴ of the convergence coefficient Σ ^4, and FIG. 7 shows that the directivity angle α, luminance unevenness δIv and convergence factor when d = 3.28 mm . The relationship with Σ is shown respectively. Note that the luminance unevenness referred to here is a variation in luminance converted from illuminance at a point 20 mm away from the light exit surface in the range of the irradiation range angle: α ′, that is,
δIv = Imax−Imin (cd)
Shows the state.
[0024]
As shown in these figures, if the lower limit of the range is exceeded and Σ ≦ 2, (1 / r) gΣ ⁴ ≦ 2, the directivity angle α becomes wide and it becomes difficult to ensure the required luminance. Also, exceeding the upper limit, 5 ≦ Σ, 20 ≦ (1 / r) gΣ ⁴ (when g ≦ 0.05 mm, 4 ≦ Σ, 12 ≦ (1 / r) gΣ ⁴ , d ≦ 3.5 mm When 10 ≦ (1 / r) gΣ ⁴ , g ≦ 0.05 mm, and d ≦ 3.5 mm, when 4 ≦ Σ and 6 ≦ (1 / r) gΣ ⁴ ), the directivity angle α becomes narrower, Since the variation in Iv increases, δIv increases.
[0025]
As a comparative example, listed in the prior art
r = 2.0mm
d = 4.75mm
n = 1.57
g = 0.15mm
Similarly, when Σ and its function are obtained in the optical semiconductor device designed as
Σ = 4.851
(1 / r) gΣ ⁴ = 40.301
And
2 <Σ <5
2 <(1 / r) gΣ ⁴ <20
Of the above conditions, the latter is not satisfied. Similarly,
r = 1.3mm
d = 3.28 mm
n = 1.57
g = 0.15mm
In the optical semiconductor device designed as
Σ = 7.585
(1 / r) gΣ ⁴ = 381.837
And is defined when d ≦ 3.5 mm.
2 <Σ <5
2 <(1 / r) gΣ ⁴ <10
Of the above conditions, the latter is not satisfied. That is, it agrees with the result obtained from the emission pattern.
[0026]
On the other hand, in each predetermined range, it can be seen that there is no luminance unevenness with a small directivity angle and δIv of 2 or less.
(Embodiment 4)
As shown in FIG. 8, in the optical semiconductor element for AF auxiliary light source having a predetermined characteristic, the resin portion side surface 6 positioned between the light emitting surface 4 of the resin portion and the pedestal 2 has a normal to the pedestal 2. The angle β (taper angle) is 10 ° or more. Then, by attaching the holder 9 from the place where the side surface 6 and the pedestal are in contact (the end portion of the resin portion), the projection pattern diameter becomes smaller than the opening diameter of the holder 9, and as shown in FIG. Even in such a case, it is possible to avoid the phenomenon of scraping by the holder 9.
[0027]
At this time, if the taper angle is less than 10 °, the projection pattern diameter cannot be made sufficiently small. Therefore, it is necessary that the taper angle is 10 ° or more. However, the taper angle should have a predetermined taper in at least one place. The entire side surface does not necessarily have a taper of 10 ° or more. The value is optimized depending on the radius of curvature of the light exit surface, the size of the light emitting element, the characteristics, the degree of variation during mass production, and the like.
[0028]
In the above embodiment, one light emitting element is used. However, a plurality of light emitting elements may be used, and the light emitting elements may be connected to the corresponding leads and controlled independently.
[0029]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the optical semiconductor device for AF auxiliary light sources which can obtain a highly accurate focusing with few brightness nonuniformities can be provided.
[Brief description of the drawings]
FIG. 1 illustrates an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 2 is a diagram showing a ray locus in an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 3 is a graph showing light distribution characteristics in an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 4 illustrates an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 5 is a graph showing characteristics of an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 6 is a graph showing characteristics of an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 7 is a graph showing characteristics of the optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 8 illustrates an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 9 illustrates an optical semiconductor device for AF auxiliary light source according to one embodiment of the present invention.
FIG. 10 is a diagram showing an optical semiconductor device used in an AF auxiliary light system.
FIG. 11 is a diagram showing an AF auxiliary light system.
FIG. 12 is a diagram showing a problem in a conventional optical semiconductor device.
FIG. 13 is a diagram showing a problem in a conventional optical semiconductor device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Base 3 Resin part 4 Light emission surface 5 Lead 6 Resin part side surface
7 optical semiconductor device (package)
8 Irradiation light (ray)
9 Holder 10 Subject 11 Lens

Claims (5)

A light emitting element, a pedestal for fixing the light emitting element, a resin portion that covers the light emitting element on the pedestal and transmits and converges light irradiated from the top surface of the light emitting element, and connects the light emitting element and an external circuit. The resin part has a light exit surface with a radius of curvature r, the distance between the light exit surface and the light emitting surface of the light emitting element is d, the refractive index of the resin part is n, and the light emitting element has a lead. When the emission size is g,
Σ = r / ((1-n) d + nr)
And the function (1 / r) gΣ ⁴
2 <Σ <5
2 <(1 / r) gΣ ⁴ <20
An optical semiconductor device for AF auxiliary light source characterized by satisfying the above. The emission size g is
g ≦ 0.05mm
When,
2 <Σ <4
2 <(1 / r) gΣ ⁴ <12
The optical semiconductor device for an AF auxiliary light source according to claim 1, wherein: The distance d between the light emitting surface and the light emitting surface of the light emitting element is:
d ≦ 3.5mm
When,
2 <(1 / r) gΣ ⁴ <10
The optical semiconductor device for an AF auxiliary light source according to claim 1, wherein: The emission size g is
g ≦ 0.05mm
When,
2 <Σ <4
2 <(1 / r) gΣ ⁴ <6
The optical semiconductor device for an AF auxiliary light source according to claim 3, wherein: In addition, a holder that is in contact with the end of the resin part and is formed in a cylindrical shape in the light emission direction is provided. 5. The optical semiconductor device for an AF auxiliary light source according to claim 1, wherein the optical semiconductor device has a taper angle .

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