Source: https://insight.rpxcorp.com/pat/US7161567B2
Timestamp: 2019-10-17 00:04:02
Document Index: 377595544

Matched Legal Cases: ['art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12']

Patent US 7,161,567 B2
1. A light emitting device comprising a reflecting member for reflecting light, a light guiding member arranged at the side of a light reflecting surface of said reflecting member, and a light emitting element for emitting light toward said light guiding member, characterized in that the surface of the light emitting side of said light guiding member comprises a direct emitting portion for directly passing the light emitted from said light emitting element through to be emitted toward the outside of the light guiding member;
a first total reflecting portion for totally reflecting the light emitted from the light emitting element toward said reflecting member and passing the light reflected by the reflecting member through to be emitted toward the outside of the light guiding member; and
a second total reflecting portion configured so that the light emitted from the light emitting element is totally reflected toward the direct emitting portion, the light totally reflected by the direct emitting portion is directed to said reflecting member, and the light reflected by the reflecting member is emitted toward the outside of the light guiding member.
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3. The light emitting device according to claim 1, characterized in that the surface of the light emitting side of said light guiding member comprises a third total reflecting portion in which the light emitted from said light emitting element is totally reflected toward said reflecting member, and the light reflected by the reflecting member is emitted to the outside of the light guiding member;
and the third total reflecting portion and the first total reflecting portion are positioned at different distances from said light emitting element.
Then, according to this embodiment, a condition in which the incident light L on the direct emitting portion 15 passes through its interface, a condition in which the incident light on the total reflecting portion 16 is totally reflected by the interface, and a condition in which the incident light on the slanted total reflecting portion 17 is totally reflected by the interface and the direct emitting portion 15 two times are to be found. As shown in FIG. 7, it is assumed that an outer diameter of the direct emitting portion 15 is D1, a diameter of a lower periphery of the slanted total reflecting portion 17 is D2 (D2≧D1), a height from the lower end to the upper end of the slanted total reflecting portion 17 in the vertical direction is H, a depth of an inserted position of the light emitting element 13 from the lower end of the slanted total reflecting portion 17 in the vertical direction is T, and an inclination of the slanted total reflecting portion 17 in the section where a shaft center of the mold part 12 penetrates is α. In addition, a relation between the inclination α of the slanted total reflecting portion 17, the height H of the slanted total reflecting portion 17, the outer diameter D1 of the direct emitting portion 15 and the inner diameter D2 of the total reflecting portion 16 is that<FORM>tan α=(D2−D1)/(2H)</FORM>that is,<FORM>D2=D1+2H tan α (1)</FORM>In addition, it is assumed that a refractive index of the mold part 12 is n1 and a refractive index of a medium contacting the front face of the mold part 12 is n2. According to this embodiment, although the front face of the mold part 12 is an interface between the resin and air, the front face of the mold part 12 may be an interface with a different resin, a multilayer reflection film or the like, and in this case, the refractive index n2 is a refractive index of a medium such as the different resin contacting the front face of the mold part 12.
The condition in which incident light on the direct emitting portion 15 is emitted from the direct emitting portion 15 like a light beam L1 shown in FIG. 7 is found as follows. That is, when it is assumed that an angle formed between the light beam L1 emitted from the light emitting element 13 to the outer peripheral end of the direct emitting portion 15 and a central axis (Z axis) of the mold part 12 is θ1, the equation is as follows,<FORM>tan θ1=D1/[2(H+T)],</FORM>that is,<FORM>θ1=arc tan [D1/2(H+T)] (2)</FORM>In order to emit the light beam L1 to the outside without being totally reflected, since the incident angle θ1 on the interface has to be smaller than a critical angle θ0=arc sin(n2/n1) of total reflection, the condition is expressed by the following equation (3).<FORM>arc tan [D1/2(H+T)]<θ0</FORM>that is,<FORM>D1<2(H+T)tan θ0 (3)</FORM>
Then, the condition in which incident light on the total reflecting portion 16 is totally reflected like a light beam L2 shown in FIG. 7 is found as follows. That is, when it is assumed that an angle formed between the light beam L2 emitted from the light emitting element 13 to the inner peripheral end of the total reflecting portion 16 and the central axis (Z axis) of the mold part 12 is θ2, the equation is provided as follows,<FORM>tan θ2=D2/(2T)</FORM>that is,<FORM>θ2=arc tan [D2/(2T)] (4)</FORM>In order to totally reflect the light beam L2, since the incident angle θ2 on the interface has to be the critical angle θ0 of the total reflection or more, the condition is expressed by the following equation (5).<FORM>arc tan [D2/(2T)]≧θ0</FORM>When the above equation (1) is used, this becomes that<FORM>D1≧2(T tan θ0−H tan α) (5)</FORM>
In addition, the condition in which incident light on the lower end of the slanted total reflecting portion 17 is totally reflected by the slanted total reflecting portion 17 and the direct emitting portion 15 like a light beam L3 shown in FIG. 7 is found as follows. Since an angle formed between the light beam L3 emitted from the light emitting element 13 to the lower end of the slanted total reflecting portion 17 and the central axis (Z axis) of the mold part 12 is the same as θ2 which is expressed by the equation (4), the incident angle θ3 of the light beam L3 on the slanted total reflecting portion 17 is expressed as follows using the inclination a of the slanted total reflecting portion 17.<FORM>θ3=90°−α−θ2=90°−α−arc tan [D2/(2T)] (6)</FORM>In order to totally reflect the light beam L3 at the slanted total reflecting portion 17, since the incident angle θ3 has to be the critical angle θ0 of the total reflection or more, the condition in which the light beam is totally reflected by the lower end of the slanted total reflecting portion 17 is expressed by the following equation (7) using the above equation (1).<FORM>90°−α−arc tan [D2/(2T)]≧θ0</FORM>that is,<FORM>D1≦2T cot(α+θ0)−2H tan α (7)</FORM>
Then, an incident angle θ4 of the light beam L3 totally reflected by the lower end of the slanted total reflecting portion 17 on the direct emitting portion 15 is as follows.<FORM>θ4=2α+θ2=2α+arc tan [D2/(2T)] (8)</FORM>In order to totally reflect the light beam L3 at the direct emitting portion 15, since the incident angle θ4 has to be the critical angle θ0 of total reflection or more, the condition in which the light beam L3 totally reflected by the lower end of the slanted total reflecting portion 17 is totally reflected by the direct emitting portion 15 also is expressed by the following equation (9).<FORM>2α+arc tan [D2/(2T)]≧θ0</FORM>that is,<FORM>D1≧2T tan(θ0−2α)−2H tan α (9)</FORM>
<maths id="MATH-US-00001" num="00001"><math overflow="scroll"><mtable><mtr><mtd><mtable><mtr><mtd><mrow><mrow><mi>θ</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><mn>5</mn></mrow><mo>=</mo><mi/><mo>⁢</mo><mrow><msup><mn>90</mn><mi>°</mi></msup><mo>-</mo><mi>α</mi><mo>-</mo><mrow><mi>θ</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><mn>1</mn></mrow></mrow></mrow></mtd></mtr><mtr><mtd><mrow><mo>=</mo><mi/><mo>⁢</mo><mrow><msup><mn>90</mn><mi>°</mi></msup><mo>-</mo><mi>α</mi><mo>-</mo><mrow><mi>arctan</mi><mo>⁡</mo><mrow><mo>[</mo><mrow><mrow><mi>D1</mi><mo>/</mo><mn>2</mn></mrow><mo>⁢</mo><mrow><mo>(</mo><mrow><mi>H</mi><mo>+</mo><mi>T</mi></mrow><mo>)</mo></mrow></mrow><mo>]</mo></mrow></mrow></mrow></mrow></mtd></mtr></mtable></mtd><mtd><mrow><mo>(</mo><mn>10</mn><mo>)</mo></mrow></mtd></mtr></mtable></math></maths>In order to totally reflect the light beam L4 at the slanted total reflecting portion 17, since the incident angle θ5 has to be the critical angle θ0 of total reflection or more, the condition in which the light beam L4 is totally reflected by the upper end of the slanted total reflecting portion 17 is expressed by the following equation (11).<FORM>90°−α−arc tan [D1/2(H+T)]≧θ0</FORM>that is,<FORM>D1≦2(H+T)cot(α+θ0) (11)</FORM>
Then, an incident angle θ6 at which the light L4 totally reflected by the upper end of the slanted total reflecting portion 17 on the direct emitting portion 15 is as follows.<FORM>θ6=2α+θ1=2α+arc tan [D1/2(H+T)] (12)</FORM>In order to totally reflect the light at the direct emitting portion 15, since the incident angle θ6 has to be the critical angle θ0 of total reflection or more, the condition in which the light L3 totally reflected by the upper end of the slanted total reflecting portion 17 is also totally reflected by the direct emitting portion 15 is expressed by the following equation (13).<FORM>2α+arc tan [D1/2(H+T)]≧θ0</FORM>that is,<FORM>D1≧2(H+T)tan(θ0−2α) (13)</FORM>
Furthermore, the condition in which the light reflected by the slanted total reflecting portion 17 impinges on the direct emitting portion 15 without impinging on an opposed surface of the slanted total reflecting portion 17 is to be considered. As shown in FIG. 7, when a distance between an incident point at which the light L3 totally reflected by the lower end of the slanted total reflecting portion 17 impinges on the direct emitting portion 15 and an outer edge of the direct emitting portion 15 is assumed to be Dx, the following equation is provided.<FORM>Dx=H[tan(θ2+2α)−tan α (14)</FORM>Since the condition in which the light reflected by the slanted total reflecting portion 17 is reflected by the direct emitting portion 15 and then, reaches the reflecting member 14 without being interrupted by the opposed region of the slanted total reflecting portion 17 is that D1/2 is more than Dx, the following equation is provided.<FORM>D1≧2H[tan(θ2+2α)−tan α (15)</FORM>is provided.
<maths id="MATH-US-00002" num="00002"><math overflow="scroll"><mtable><mtr><mtd><mrow><mrow><mo>[</mo><mrow><mi>Equation</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo>⁢</mo><mn>1</mn></mrow><mo>]</mo></mrow><mo>⁢</mo><mstyle><mtext></mtext></mstyle><mo>⁢</mo><mrow><mi>Z</mi><mo>=</mo><mrow><mfrac><mrow><mi>CV</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>ρ</mi><mn>2</mn></msup></mrow><mrow><mn>1</mn><mo>+</mo><msqrt><mrow><mn>1</mn><mo>-</mo><mrow><mrow><msup><mi>CV</mi><mn>2</mn></msup><mo>⁡</mo><mrow><mo>(</mo><mrow><mi>CC</mi><mo>+</mo><mn>1</mn></mrow><mo>)</mo></mrow></mrow><mo>⁢</mo><msup><mi>ρ</mi><mn>2</mn></msup></mrow></mrow></msqrt></mrow></mfrac><mo>+</mo><mrow><mi>A</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>ρ</mi><mn>4</mn></msup></mrow><mo>+</mo><mrow><mi>B</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>ρ</mi><mn>6</mn></msup></mrow><mo>+</mo><mrow><mi>C</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>ρ</mi><mn>8</mn></msup></mrow><mo>+</mo><mrow><mi>D</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>ρ</mi><mn>10</mn></msup></mrow><mo>+</mo><mi>…</mi></mrow></mrow><mo>⁢</mo><mstyle><mtext></mtext></mstyle><mo>⁢</mo><mrow><mi>However</mi><mo>,</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><mrow><mi>ρ</mi><mo>=</mo><mover><mrow><mrow><mo>)</mo><msup><mi>X</mi><mn>2</mn></msup></mrow><mo>+</mo><msup><mi>Y</mi><mn>2</mn></msup></mrow><mi>_</mi></mover></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>16</mn><mo>)</mo></mrow></mtd></mtr></mtable></math></maths>where X, Y and Z constitute orthogonal coordinates in which a center of the reflecting member 14 is a starting point as shown in FIG. 7, and the Z axis coincides with the light axis of the reflecting member 14 and the central axis of the mold part 12. In addition, CV is a curvature (constant number) of the reflecting member 14, CC is a conic coefficient, and A, B, C, D, . . . are fourth, sixth, eighth, tenth, . . . aspheric coefficients, respectively.
<maths id="MATH-US-00003" num="00003"><math overflow="scroll"><mtable><mtr><mtd><mrow><mrow><mo>[</mo><mrow><mi>Equation</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo>⁢</mo><mn>2</mn></mrow><mo>]</mo></mrow><mo>⁢</mo><mstyle><mtext></mtext></mstyle><mo>⁢</mo><mrow><mi>Z</mi><mo>=</mo><mrow><mfrac><mrow><msup><mi>cvxX</mi><mn>2</mn></msup><mo>-</mo><msup><mi>cvY</mi><mn>2</mn></msup></mrow><mrow><mn>1</mn><mo>+</mo><msqrt><mrow><mn>1</mn><mo>-</mo><mrow><mrow><msup><mi>cvx</mi><mn>2</mn></msup><mo>⁡</mo><mrow><mo>(</mo><mrow><mi>ccx</mi><mo>+</mo><mn>1</mn></mrow><mo>)</mo></mrow></mrow><mo>⁢</mo><msup><mi>X</mi><mn>2</mn></msup></mrow><mo>-</mo><mrow><mrow><msup><mi>cv</mi><mn>2</mn></msup><mo>⁡</mo><mrow><mo>(</mo><mrow><mi>cc</mi><mo>+</mo><mn>1</mn></mrow><mo>)</mo></mrow></mrow><mo>⁢</mo><msup><mi>Y</mi><mn>2</mn></msup></mrow></mrow></msqrt></mrow></mfrac><mo>+</mo><mrow><mi>a</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>X</mi><mn>4</mn></msup></mrow><mo>+</mo><mrow><mi>b</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>Y</mi><mn>4</mn></msup></mrow><mo>+</mo><mrow><mi>c</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>X</mi><mn>6</mn></msup></mrow><mo>+</mo><mrow><mi>d</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo>⁢</mo><msup><mi>Y</mi><mn>6</mn></msup></mrow><mo>+</mo><mi>…</mi></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>17</mn><mo>)</mo></mrow></mtd></mtr></mtable></math></maths>where X, Y and Z constitute orthogonal coordinates in which a center of the reflecting member 14 is a starting point also, and the Z axis coincides with the light axis of the reflecting member 14 and the central axis of the mold part 12. In addition, when the equation (17) is expressed such that Z=G (X, Y), a curvature (constant number) of a curve expressed by Z=G(X, Y) is cν and a conic coefficient is cc, and a curvature (constant number) of curve expressed by Z=G (0, Y) is cνx (≠cν) and a conic coefficient is ccx. In addition, a, b, c, d, . . . are high-order aspheric coefficients, respectively.
FIG. 9 is a reference view for calculating the minimum width Dx of the flat face 22, which is required in theory. When it is assumed that an emission angle of the light L emitted from the light emitting element 13 toward the lower end of the slanted total reflecting portion 17 is θ2, an inclination of the slanted total reflecting portion 17 is α, and a height of the slanted total reflecting portion 17 is H, the width Dx of the ring-shaped flat face 22 is found from FIG. 9 as follows. In addition, the width Dx is the same as in the equation (14).<FORM>Dx=H[tan(θ2+2α)−tan α] (18)</FORM>(Third Embodiment)
FIG. 12B is a view showing a relation between a depth δ of the groove 25 and an amount of shift of the light. Assuming that the depth of the groove 25 measured from the total reflecting portion 16 is δ and the depth of the inserted position of the light emitting element 13 measured from the total reflecting portion 16 perpendicularly is T, the light L emitted from the light emitting element 13 at the emission angle θ7 (≧θ) is to be considered. In the case where the groove 25 does not exist, when it is assumed that a distance between a position in which the light L totally reflected by the total reflecting portion 16 reaches the horizontal surface on which the light emitting element 13 is provided, and the light emitting element 13 is K2, that is expressed as follows.<FORM>K2=2T tan θ7 (19)</FORM>In addition, when it is assumed that a distance between a position in which the light L totally reflected by the total reflection face 26 positioned at the bottom of the groove 25 reaches the horizontal surface on which the light emitting element 13 is provided and the light emitting element 13 is K1, that is expressed as follows.<FORM>K1=2(T−δ)tan θ7 (20)</FORM>Accordingly, the shifted amount K2−K1 is as follows using the equations (19) and (20).<FORM>K2−K1=2δ tan θ7 (21)</FORM>Thus, it can be understood that the emitting position of the light L can be controlled by adjusting the shifted amount D2−D1 of the light totally reflected by the total reflection face 26 by adjusting the depth δ of the groove 25.(Fourth Embodiment)
When T, H, α or the like is defined as described above and it is assumed that the emission angle of the light emitted from the light emitting element 13 to the lower end of the slanted total reflecting portion 17 is θ2, the condition in which the light emitted from the light emitting element 13 is totally reflected by the slanted total reflecting portion 17 is as follows,<FORM>90°−θ2−α≧θ0 (θ0 is a critical angle of total reflection)</FORM>that is, like the equation (7) in the first embodiment, and<FORM>D1≦2T cot(α+θ0)−2H tan α (22)</FORM>is provided.
Furthermore, a condition in which the light totally reflected by the slanted total reflecting portion 17 is totally reflected by the direct emitting portion 15 is as follows like the equations (13) and (15) in the first embodiment.<FORM>D1≧2(H+T)tan(θ0−2α) (23)</FORM><FORM>D1≧2H[tan(θ2+2α)−tan α] (24)</FORM>
Moreover, since the incident angle of the light on the end of the inner periphery of the total reflection face 26 is θ2+β, as the condition in which the incident light on the total reflection face 26 is totally reflected by the total reflection face 26, it follows that θ2+β is the critical angle θ0 of total reflection or more, that is,<FORM>β≧θ0−θ2 (25)</FORM>(Fifth Embodiment)
FIG. 15 is a perspective view showing a light emitting device 28 viewed from the back face according to still another embodiment of the present invention, and FIG. 16 is a sectional view thereof. According to the light emitting device 28, a reflecting member 29 formed on a back face of a mold part 12 consists of a plurality of ring-shaped reflecting portions 29a, 29b, . . . , which form Fresnel reflection face. When the reflecting member 29 is formed in the shape of the Fresnel reflection face, the light emitting device 28 can be further thinned. Besides, each region can be designed optimally by designing each of the plural reflecting portions 29a, 29b, . . . with a independent parameter to each other, thereby to be able to emit the light more uniformly.
FIG. 17 is a sectional view showing a light emitting device 30 according to still another embodiment of the present invention. Referring to the light emitting device 30, a groove 25 is formed between a direct emitting portion 15 and a total reflecting portion 16 at a front face of a mold part 12, and a total reflection face 26 is formed on the bottom of the groove 25. A reflecting member 31 formed on the back face of the mold part 12 consists of four ring-shaped reflecting portions 31a, 31b, 31c and 31d, which form Fresnel reflection face. In this constitution, the reflecting portion 31d is configured and positioned so as to receive the light which was emitted from a light emitting element 13 and totally reflected by the total reflecting portion 16 and to emit forward from the total reflecting portion 16. The reflecting portion 31c is configured and positioned so as to receive the light which was emitted from the light emitting element 13 and totally reflected by the total reflection face 26 and to emit forward from the total reflecting portion 16. The reflecting portion 31b is configured and positioned so as to receive the light which was emitted from the light emitting element 13 and totally reflected by a slanted total reflecting portion 17 and the direct emitting portion 15 and to emit forward from the front face of the mold part 12. The reflecting portion 31a is configured and positioned so as to receive the light which was emitted from the light emitting element 13 at a large emission angle to impinge directly on the reflection face 31 and to emit forward from the front face of the mold part 12.
According to this embodiment, since the reflecting portions 31a, 31b, 31c and 31d are provided depending on the characteristics of the light path of the incident light and each of the reflecting portions 31a, 31b, 31c and 31d can be designed depending on each characteristic, light can be further uniformly emitted from a light source apparatus.
FIG. 27 are views showing various front configurations of light emitting devices according to the present invention. Although description was made of the light emitting device having the front configuration of a circle (that is, a perfect circle, an ellipse or the like) in the above embodiments, the front configuration of the light emitting device is not limited to the circle. According to a light emitting device 49 shown in FIG. 27A, a light emitting element 49a is designed in the shape of the perfect circle shown by a dotted line and then, peripheral six portions are cut to be formed as a regular hexagon. According to a light emitting device 50 shown in FIG. 27B, a light emitting element 50a is designed in the shape of the perfect circle shown by a dotted line and then, peripheral four portions are cut to be formed as a regular tetragon. According to a light emitting device 51 shown in FIG. 27C, a light emitting element 51a is designed in the shape of the perfect circle shown by a dotted line and then, peripheral four portions are cut to be formed as a rectangle. According to a light emitting device 52 shown in FIG. 27D, a light emitting element 52a is designed in the shape of the perfect circle shown by a dotted line and then, peripheral four portions are cut to be formed as a rectangle. In addition, the peripheral portions are cut as an order in design and they are not cut in the real manufacturing process.
Homma, Kenji, Kiyomoto, Hironobu, Ayabe, Takahiro
345 82- 84, 345/46, 359/247, 359/267, 359/318, 362/16, 362/555, 362/606