JP2014202801A - Optical reflection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small size optical reflection element capable reducing dynamic deflection of a reflecting part.SOLUTION: The optical reflection element includes: a fixing part 22; a first vibration member 24a connected to the other end of the fixing part 22; a second vibration member 24b which is connected in a direction opposing to the first vibration member 24a; and a reflecting part 26 connected to the first and second vibration member 24a and 24b so as to rotate. The first vibration member 24a includes: a first vibration part 23a connected to the fixing part 22; a second vibration part 23b positioned between the reflecting part 26 and the first vibration part 23a and extending in a direction different from the direction of the first vibration part 23a. The second vibration member 24b includes: a third vibration part 23c connected to the fixing part 22; and a fourth vibration part 23d positioned between the reflecting part 26 and the third vibration part 23c and extending in a direction different from the direction of the third vibration part 23c. The spring constant of the second vibration part 23b is set to be smaller than the spring constant of the first vibration part 23a, and the spring constant of the fourth vibration part 23d is set to be smaller than the spring constant of the third vibration part 23c.

Description

  The present invention relates to an optical reflection element used in an image projection apparatus or the like using laser light.

  Projection display devices such as head-up displays and small projectors that scan light from a light source such as a laser have been put into practical use. A conventional optical reflection element used in such a display device will be described with reference to FIG.

  Conventionally, this type of optical reflecting element 1 includes a fixed frame 3, 4 provided on a base 2 as shown in FIG. 6, first connection portions 5, 6 connected to the fixed frame 3, 4, Connected to the first connecting portions 5 and 6, the second connecting portions 9 and 10 connected to the driving portions 7 and 8, and the second connecting portions 9 and 10, respectively. The first connecting portions 5 and 6 and the second connecting portion 9 are constituted by the vibrating members 11 and 12 and the reflecting portion 13 supported by the vibrating members 11 and 12 by applying a voltage to the driving portions 7 and 8. By twisting and deforming 10, the reflecting portion 13 can be rotated around the rotation shaft 14, and light from a light source such as a laser can be scanned.

  Here, FIG. 7 shows a diagram of the reflection unit 13 when the reflection unit 13 during driving of the conventional optical reflection element 1 is viewed from a side surface of the reflection unit 13 in a direction orthogonal to the rotation shaft 14. When the conventional optical reflection element 1 is used, as shown in FIG. 7, a dynamic deflection occurs in which the reflecting portion 13 bends during driving, causing a problem that the reflected laser beam is enlarged.

  As a means for solving this problem, Patent Literature 1 discloses a reflection unit 13 in order to suppress transmission of dynamic deflection due to rotation of the first connection units 5 and 6 and the second connection units 9 and 10 to the reflection unit 13. The structure which makes the vibration members 11 and 12 between the part 13 and the 2nd connection parts 9 and 10 make a meander structure is disclosed.

Japanese Patent No. 4507983

  However, since the configuration of the above-mentioned prior art document 1 is provided with a drive unit for rotating the reflection unit between the torsion bar and the torsion bar, there is a problem that the size of the element increases, and the second torsion bar. Since the meander structure between the reflecting part and the reflecting part extends in a direction perpendicular to the rotating axis of the reflecting part, the effect of suppressing the dynamic deflection due to a decrease in the spring constant in the rotating direction of the reflecting part is difficult to be obtained. was there.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a miniaturized element in which dynamic bending is suppressed as compared with the above-mentioned prior art document 1.

  In order to solve the above problems, the present invention provides a fixed frame, a first vibration member connected to the other end of the fixed frame, and a second vibration connected in a direction opposite to the first vibration member. A first vibration part connected to the fixed frame, the first vibration member having a member, and a reflection part rotatably connected to the first vibration member and the second vibration member; And a second vibrating part that is located between the reflecting part and the first vibrating part and extends in a direction different from the first vibrating part, and the second vibrating member includes the second vibrating member, A third vibrating part connected to a fixed frame and a fourth vibrating part located between the reflecting part and the third vibrating part and extending in a direction different from the third vibrating part The spring constant of the second vibration part is lower than the spring constant of the first vibration part, and the spring constant of the fourth vibration part is a third value. It was lower configuration than the moving parts.

  The optical reflection element of the present invention is a second vibration in which the connection portion and the reflection portion extend in a direction different from that of the first vibration portion and the first vibration portion, and have a lower spring constant than the first vibration portion. By connecting via the part, the spring constant in the rotating direction of the reflecting part can be reduced, and an effect is obtained that an optical reflecting element capable of suppressing the dynamic deflection and miniaturizing can be provided.

The top view of the optical reflection element in Embodiment 1 of this invention Sectional drawing in the AA line of FIG. 1 of the optical reflection element The top view of the optical reflective element in Embodiment 2 of this invention The top view of the optical reflective element in Embodiment 3 of this invention Plan view of the optical reflection element Plan view of a conventional optical reflecting element The figure explaining the dynamic bending of a reflection part

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view of an optical reflecting element according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the optical reflecting element 20 according to the first embodiment of the present invention includes a fixed portion 22 including a rectangular fixed frame 21a and a connecting portion 21b, a first vibrating portion 23a, and a second vibrating portion. A vibration member 24a made of 23b, a second vibration member 24b made of a third vibration portion 23c and a fourth vibration portion 23d, a drive portion 25, and a reflection portion 26. One end of the connecting portion 21b is fixed to the approximate center of the short side of the fixed frame 21a, the other end of the connecting portion 21b is connected to one end of the first vibrating portion 23a and the third vibrating portion 23c, and the first vibrating portion 23a. The other end of the third vibrating part 23c is connected to one end of the second vibrating part 23b and the fourth vibrating part 23d, respectively, and the first vibrating member 24a and the second vibrating member 24b are connected to each other. It is connected to the fixed frame 21a via 21b. The other ends of the second vibration part 23b and the fourth vibration part 23d are connected to a reflection part 26 for reflecting light such as laser light, and the drive part 25 is connected to the first vibration part 23a and the third vibration part 23d. Is provided on the vibration part 23c. The fixed frame 21a, the connecting portion 21b, the first vibration member 24a, and the second vibration member 24b are made of the same member, and silicon having a high elastic strength, mechanical strength, and Young's modulus is used as a substrate material.

  FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 2, the first vibration unit 23 a and the third vibration unit 23 c provided with the drive unit 25 include a silicon substrate 27, a lower electrode film 28 formed on the silicon substrate 27, and a lower electrode. A piezoelectric film 29 formed on the film 28 and an upper electrode film 30 formed on the piezoelectric film 29 are provided. The lower electrode film 28 is made of platinum, the piezoelectric film 29 is made of lead zirconate titanate (PZT), and the upper electrode film 30 is made of gold. Note that the material of each film can be collectively formed by a thin film process such as vapor deposition, sol-gel, CVD, or sputtering, and a fine pattern can be accurately processed by an etching technique using a photolithography technique. .

  When a predetermined potential difference is applied to the lower electrode film 28 and the upper electrode film 30, a predetermined potential difference is applied to the piezoelectric film 29, and the piezoelectric film 29 expands and contracts in a direction parallel to the upper surface of the silicon substrate 27 by the inverse piezoelectric effect. This causes the silicon substrate 27 to vibrate up and down. Here, by applying an electric field having an opposite phase to the driving unit 25, the first vibrating unit 23a and the third vibrating unit 23c vibrate in opposite directions, and thus the reflecting unit 26 is rotated around the rotation shaft 31. Move. Thus, by providing the driving unit 25 on the first vibrating unit 23a and the third vibrating unit 23c, it is not necessary to provide a driving unit on the connecting unit 21b, and a portion where the driving unit is provided is provided. Since it is not necessary to provide other than the part which comprises the optical reflective element 20 of Embodiment 1 of this invention, an optical reflective element can be reduced in size.

  Next, effects of the first embodiment of the present invention will be described. In addition, although it demonstrates using the 1st vibration part 23a and the 2nd vibration part 23b which comprise the 1st vibration member 24a, the 3rd vibration part 23c and the 4th which comprise the 2nd vibration member 24b are demonstrated. The same effect can be obtained for the vibrating portion 23d.

  Here, since the cause of the dynamic deflection is the inertial force applied to the reflecting portion 26, the inertial force applied to the reflecting portion 26 increases as the distance from the rotation shaft 31 increases, and the dynamic deflection also increases. To do. The reflecting portion 26 realizes a swinging motion by the first vibrating member 24a and the second vibrating member 24b, and moves according to the support method of the reflecting portion 26 of the first vibrating member 24a and the second vibrating member 24b. The distribution of dynamic deflection changes. That is, the distribution of dynamic deflection is determined by the balance between the inertial force applied to the reflecting portion 26 and the support method of the reflecting portion 26.

  In Embodiment 1 of the present invention, the second vibrating portion 23b is formed to be thinner than the first vibrating portion 23a. Thereby, since the spring constant of the 2nd vibration part 23b becomes lower than the 1st vibration part 23a, compared with the case where the 1st vibration part 23a and the 2nd vibration part 23b are formed with the same thickness, When the reflecting portion 26 is rotated, the second vibrating portion 23b is greatly bent, and the distribution of dynamic bending changes. For this reason, it becomes possible to disperse the bending of the reflection part 26 by the 2nd vibration part 23b, and it becomes possible to reduce the dynamic bending of the reflection part 26 now.

  Further, since the spring constant of the second vibrating portion 23b is lower than that of the first vibrating portion 23a, the distance from the portion having a low spring constant to the reflecting portion 26 is shortened, so that the larger reflecting portion 26 A dynamic deflection suppressing effect can be obtained.

  Furthermore, the second vibrating portion 23b can reduce the spring constant in the rotating direction as it is closer to the rotating shaft 31 of the reflecting portion 26. The optical reflecting element 20 according to the first embodiment of the present invention is formed so that the second vibrating portion 23b is parallel to the rotation shaft 31 as shown in FIG. Since the spring constant in the rotational direction of the reflecting portion 26 can be lowered compared to a configuration that is not parallel to the rotating shaft 31, dynamic deflection of the reflecting portion 26 can be further reduced.

  In the first embodiment of the present invention, the second vibration part 23b supports the portion 32 farthest from the rotation shaft 31 where the inertial force applied to the reflection part 26 is the largest when the reflection part 26 is rotated. By doing so, the dynamic deflection reducing effect of the first embodiment of the present invention can be improved.

  In the first embodiment of the present invention, the thickness of the second vibrating portion 23b is made thinner than that of the first vibrating portion 23a. However, the second vibrating portion 23b is made of a material such as silicon oxide. The spring constant of the second vibration part 23b may be smaller than the spring constant of the first vibration part 23a, for example, by changing to a material that is less rigid than silicon, which is the material of the first vibration part.

  In the first embodiment of the present invention, the connection portion 21b, the first vibration portion 23a, the drive portion 25, and the second vibration portion 23b are described as a pair. The same effect can be obtained by providing only one side with respect to the reflection part 26 and supporting the reflection part 26 on one side. As shown in FIG. 1, the driving of the optical reflecting element 20 can be made more stable by configuring each part as a pair and supporting the reflecting portion 26 from both sides.

(Embodiment 2)
Embodiment 2 of the present invention will be described below with reference to the drawings.

  The structure, manufacturing method, and driving method of the optical reflecting element 40 according to the second embodiment of the present invention are the same as the structure of the optical reflecting element 20 according to the first embodiment of the present invention. Only the differences will be described. The optical reflecting element 40 according to the second embodiment of the present invention is different from the first embodiment of the present invention in that the second vibrating portion is formed in a so-called meander shape in which a straight portion and a folded portion are formed. Is different.

  FIG. 3 shows a plan view of the optical reflecting element 40 according to Embodiment 2 of the present invention.

  As shown in FIG. 3, the optical reflecting element 40 according to the second embodiment of the present invention includes a fixed portion 42 including a rectangular fixed frame 41a and a connecting portion 41b, a first vibrating portion 43a, and a second vibrating portion. The first vibration member 44a made of 43b, the second vibration member 44b made of the third vibration portion 43c and the fourth vibration portion 43d, the drive portion 45, and the reflection portion 46 are provided. One end of the connection part 41b is fixed to the approximate center of the short side of the fixed frame 41a, the other end of the connection part 41b is connected to one end of the first vibration part 43a and the third vibration part 43c, and the first vibration part 43a. The other end of the third vibration part 43c is connected to one end of the second vibration part 43b and the fourth vibration part 43d, respectively, and the first vibration member 44a and the second vibration member 44b are connected to each other. It is connected to the fixed frame 41a via 41b. The other ends of the second vibration part 43b and the fourth vibration part 43d are connected to a reflection part 46 for reflecting light such as laser light, and the drive part 45 is connected to the first vibration part 43a and the third vibration part 43d. Is provided on the vibration part 43c. The second vibrating portion 43 b and the fourth vibrating portion 43 d are composed of a straight portion 47 and a folded portion 48, and the straight portion 47 extends in a direction parallel to the rotation shaft 51 of the reflecting portion 46.

  The effect of the optical reflecting element 40 according to the second embodiment of the present invention will be described. In addition, although demonstrated using the 1st vibration part 43a and the 2nd vibration part 43b which comprise the 1st vibration member 44a, the 3rd vibration part 43c and the 4th which comprise the 2nd vibration member 44b are demonstrated. The same effect can be obtained with respect to the vibrating portion 43d.

  Since the second vibrating portion 43b of the optical reflecting element 40 is formed in a meander shape, the spring constant in the rotational direction of the second vibrating portion 43b is lower than that of the first vibrating portion 43a. Here, since it is not necessary to make the material and thickness of the second vibration part 43b different from the first vibration part 43a, the first vibration part 43a and the second vibration part 43b can be integrally formed, Since the manufacturing process can be simplified, productivity can be improved.

  Further, since the second vibrating portion 43b has a meander shape, the spring constant in the rotational direction of the second vibrating portion 43b can be easily obtained by changing the length and width of the linear portion 47 and the folded portion 48. It becomes possible to adjust to the value of. Further, since the first vibrating portion 43a and the second vibrating portion 43b can be formed with the same thickness, the mechanical strength can be improved as compared with the case where the thickness of the second vibrating portion 43b is reduced. . In addition, when the 2nd vibration part 43b is made into a meander shape, about 14% of dynamic bending can be suppressed rather than the case where the 2nd vibration part 43b is made into a linear shape.

  Further, the optical reflecting element 40 according to the second embodiment of the present invention is first with respect to the first straight line 53 a passing through the first end 52 a farthest from the rotation shaft 51 in the reflection portion 46 and the rotation shaft 51. When the second straight line 53b passing through the second end 52b on the opposite side of the second end 52a is used, the center of gravity G of the second vibrating part 43b is outward with respect to the first straight line 53a and the second straight line 53b. positioned.

  Here, the distribution of dynamic deflection changes depending on the distance in the direction perpendicular to the rotation axis 51 of the first end portion 52a and the center of gravity G of the second vibration portion 43b. As the distance of the first end portion 52a is shorter, the dynamic deflection is concentrated on the second vibrating portion 43b, so that the dynamic deflection of the reflecting portion 46 can be further reduced.

  In the conventional optical reflecting element as shown in FIG. 6, the center of gravity G of the vibrating members 11, 12, which is a portion having a low spring constant, is on the inner side with respect to the straight line passing through the point farthest from the rotating shaft 14 of the reflecting portion 13. The distance between the center of gravity G of the vibrating members 11 and 12 and the point farthest from the rotation shaft 14 of the reflecting portion 13 is far from the optical reflecting element 40 shown in FIG. As described above, in the optical reflecting element 40 according to the second embodiment of the present invention, the position of the center of gravity G of the second vibrating portion 43b is outside the first straight line 53a and the second straight line 53b. The distance between the center of gravity G of the vibration part 43b and the first end part 52a can be shortened.

  Further, the area of the drive unit 45 can be increased by setting the second vibrating portion 43b in a direction parallel to the rotation shaft 51 and the center of gravity G outside the first straight line 53a and the second straight line 53b. Thereby, the drive efficiency of the optical reflection element 40 can be improved.

  In addition, although the center of gravity G of the 2nd vibration part 43b became the outer side with respect to the 1st straight line 53a and the 2nd straight line 53b, it demonstrated that the center of gravity G of the 1st vibration member 44a and the 1st straight line 53a. The same effect can be obtained even if it is configured to be outside the second straight line 53b.

(Embodiment 3)
Embodiment 3 of the present invention will be described below with reference to the drawings.

  The structure, manufacturing method, and driving method of the optical reflecting element 60 according to the third embodiment of the present invention are the same as those of the optical reflecting element 40 according to the second embodiment of the present invention. Only the differences will be described. The optical reflecting element 60 according to the third embodiment of the present invention is different from the second embodiment of the present invention in that the straight line portion of the second vibrating portion is formed in a direction perpendicular to the rotation axis of the reflecting portion. Yes.

  FIG. 4 is a plan view of the optical reflecting element 60 according to Embodiment 3 of the present invention.

  As shown in FIG. 4, the optical reflecting element 60 according to the third embodiment of the present invention includes a fixed portion 62 including a rectangular fixed frame 61a and a connecting portion 61b, a first vibrating portion 63a, and a second vibrating portion. The first vibration member 64a made of 63b, the second vibration member 64b made of the third vibration portion 63c and the fourth vibration portion 63d, the drive portion 65, and the reflection portion 66 are provided. One end of the connecting portion 61b is fixed to the approximate center of the short side of the fixed frame 61a, the other end of the connecting portion 61b is connected to one end of the first vibrating portion 63a and the third vibrating portion 63c, and the first vibrating portion 63a. The other end of the third vibrating part 63c is connected to one end of the second vibrating part 63b and the fourth vibrating part 63d, and the first vibrating member 64a and the second vibrating member 64b are connected to the connecting part 61b, respectively. Is connected to the fixed frame 61a. The other ends of the second vibration part 63b and the fourth vibration part 63d are connected to a reflection part 66 for reflecting light such as laser light, and the drive part 65 is connected to the first vibration part 63a and the third vibration part 63d. Is provided on the vibration part 63c. The second vibrating portion 63b and the fourth vibrating portion 63d are composed of a straight portion 67 and a folded portion 68, and the straight portion 67 extends in a direction perpendicular to the rotation shaft 71 of the reflecting portion 66.

  The effect of the optical reflecting element 60 in Embodiment 3 of the present invention will be described. In addition, although demonstrated using the 1st vibration part 63a and the 2nd vibration part 63b which comprise the 1st vibration member 64a, the 3rd vibration part 63c and the 4th which comprise the 2nd vibration member 64b are demonstrated. The same effect can be obtained for the vibrating part 63d.

  The linear portion 67 of the optical reflecting element 60 extends in a direction perpendicular to the rotation shaft 71, so that the reflection portion is compared with a structure in which the linear portion 67 extends in a direction parallel to the rotation shaft 71. The spring constant in the rotational direction of 66 can be reduced. For this reason, it becomes possible to further reduce the dynamic deflection applied to the reflecting portion 66 when the optical reflecting element 60 is driven, and to reduce the size of the optical reflecting element while suppressing the dynamic deflection while maintaining the driving efficiency. Can be provided. In addition, when the 2nd vibration part 63b is made into a meander shape, about 24% of dynamic bending can be suppressed rather than the case where the 2nd vibration part 63b is made into a linear shape.

  Further, the drive unit 65 has been described using the structure provided on the first vibrating unit 63a and the third vibrating unit 63c, but as shown in FIG. 5, the linear portion of the second vibrating unit 83b. The drive unit 65 may be provided on the 67. The effect when the drive part 65 is provided on the linear part 67 is demonstrated. In addition, the code | symbol attaches | subjects the same code | symbol to the thing of the same shape as the structure shown in FIG.

  The optical reflecting element 80 shown in FIG. 5 is the same as the optical reflecting element 60 in FIG. 4 in that the first vibrating member 84a and the second vibrating member 84b are provided with driving parts. The difference is that the second vibrating portion 83b and the fourth vibrating portion 83d are provided on the straight line portion 67. Accordingly, when an electric field is applied to the drive unit 65, a piezoelectric film (not shown) expands and contracts in the plane direction with respect to the drive unit 65 due to the inverse piezoelectric effect, and drives the second vibration unit 83b and the fourth vibration unit 83d. The portion provided with the portion 65 vibrates up and down. Thereby, the vibration of the drive part 65 is superimposed and the reflection part 66 is rotated largely. At this time, the optical reflecting element 80 can be further reduced in size by providing the driving unit 65 for rotating the reflecting unit 66 at a position closer to the reflecting unit 66 than the first vibrating unit 63a. Yes.

  The optical reflecting element of the present invention can provide an optical reflecting element that suppresses the occurrence of dynamic bending of the reflecting portion when the actuator is scanned and the laser beam is difficult to expand. Further, the optical reflecting element can be reduced in size, which is useful for a head-up display and a small projector.

20, 40, 60, 80 Optical reflection element 21a, 41a, 61a Fixed frame 21b, 41b, 61b Connection part 22, 42, 62 Fixed part 23a, 43a, 63a First vibration part 23b, 43b, 63b, 83b Second Vibration parts 23c, 43c, 63c Third vibration parts 23d, 43d, 63d, 83d Fourth vibration parts 24a, 44a, 64a, 84a First vibration members 24b, 44b, 64b, 84b Second vibration members 25 , 45, 65 Drive unit 26, 46, 66 Reflecting unit 27 Silicon substrate 28 Lower electrode film 29 Piezoelectric film 30 Upper electrode film 31, 51, 71 Rotating shaft 32 Farthest part 47, 67 Linear part 48, 68 Folding part 52a First end portion 52b Second end portion 53a First straight line 53b Second straight line

Claims (9)

A fixed part;
A first vibrating member connected to the fixed portion;
A second vibrating member connected in a direction facing the first vibrating member;
A reflective portion rotatably connected to the first vibrating member and the second vibrating member;
The first vibration member is located between the first vibration part connected to the fixed part, the reflection part, and the first vibration part, and extends in a direction different from the first vibration part. Constituted by the existing second vibration part,
The second vibrating member is positioned between the third vibrating unit connected to the fixed unit, the reflecting unit, and the third vibrating unit, and extends in a direction different from the third vibrating unit. Constituted by the existing fourth vibration part,
A spring constant of the second vibrating part is lower than a spring constant of the first vibrating part;
The optical reflection element, wherein the spring constant of the fourth vibration part is lower than that of the third vibration part. A straight line that passes through the first end of the reflecting portion in a direction substantially orthogonal to the rotating shaft of the reflecting portion and is substantially parallel to the rotating shaft is defined as a first straight line.
A straight line that passes through the second end of the reflecting part on the opposite side of the first end in a direction substantially orthogonal to the turning axis of the reflecting part and is substantially parallel to the turning axis is defined as a second straight line. When
2. The optical reflecting element according to claim 1, wherein the center of gravity of the second vibrating part and the center of gravity of the fourth vibrating part are located outside the first straight line and the second straight line. . 2. The optical reflecting element according to claim 1, wherein the second vibrating portion and the fourth vibrating portion are configured by alternately connecting at least two linear portions and at least one folded portion. . The optical reflecting element according to claim 3, wherein the linear portion is formed in a direction substantially orthogonal to a rotation axis of the reflecting portion. The optical reflecting element according to claim 4, wherein a driving unit that rotates the reflecting unit is provided in the linear portion. 2. The optical reflecting element according to claim 1, wherein the first vibrating member and the second vibrating member are connected to the reflecting portion at a portion farthest from a rotation axis of the reflecting portion. 2. The optical reflection element according to claim 1, wherein the second vibration part and the fourth vibration part extend in a direction substantially parallel to a rotation axis of the reflection part. A fixed part;
A first vibrating member connected to the fixed portion;
A second vibrating member connected in a direction facing the first vibrating member;
A reflective portion rotatably connected to the first vibrating member and the second vibrating member;
A straight line that passes through the first end of the reflecting portion in a direction substantially orthogonal to the rotating shaft of the reflecting portion and is substantially parallel to the rotating shaft is defined as a first straight line.
A straight line that passes through the second end of the reflecting part on the opposite side of the first end in a direction substantially orthogonal to the turning axis of the reflecting part and is substantially parallel to the turning axis is defined as a second straight line. When
The center of gravity of the 1st oscillating member and the center of gravity of the 2nd oscillating member are located in the outside to the 1st straight line and the 2nd straight line, The optical reflective element characterized by things. The optical reflection element according to claim 1, wherein the connection portion and the vibration portion are formed in a pair so as to face each other with the reflection portion interposed therebetween.

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