JP5229242B2 - Optical scanner - Google Patents

Description

The present invention relates to an optical scanner.

2. Description of the Related Art Conventionally, various types of optical scanners that scan a light in a predetermined direction by swinging a mirror unit around a swing axis have been proposed.
For example, a conductive substrate that is hollowed out leaving a mirror part and a pair of torsion beam parts having one end connected to both sides of the mirror part is supported in a cantilevered manner by one end of the substrate. In addition, there is an optical scanner in which a piezoelectric element is formed on a part of the substrate (for example, see Patent Document 1).

JP 2006-293116 A

  In the configuration described in Patent Document 1 described above, the piezoelectric element provided on the substrate is formed by an aerosol deposition method (AD method) in which film formation is performed by spraying nano-sized fine particles such as PZT. Yes. Thereafter, an upper electrode is formed on the upper surface of the piezoelectric element by an AD method, gold sputtering, or the like. However, the manufacturing method in which the piezoelectric element is formed on the substrate by the AD method has a problem that the manufacturing process becomes complicated.

Therefore, a manufacturing method is conceivable in which a piezoelectric element having a thickness of 1 μm to 100 μm with electrodes formed on the upper and lower surfaces is directly bonded onto a substrate with a conductive adhesive.
However, if the amount of the conductive adhesive applied is large, the conductive adhesive may protrude from the outer peripheral portion of the piezoelectric element, and the electrodes formed on the upper and lower surfaces may be short-circuited. There is a problem that it is difficult to adhere to the substrate across the board, and the driving efficiency of the piezoelectric element is lowered.

Accordingly, the present invention has been made to solve the above-described problems, and can reliably prevent a short circuit due to a conductive adhesive between electrodes formed on the upper and lower surfaces of the piezoelectric element. and an object thereof is to provide an optical scanner capable of improving the driving efficiency.

  In order to achieve the above object, an optical scanner according to claim 1 is an optical scanner that scans light in a predetermined direction by displacing a mirror unit around a swing axis, and has a conductive surface, and the mirror unit is provided with a conductive surface. A substrate that is slidably supported, a piezoelectric element that is bonded to the surface of the substrate and swings the mirror portion about a swing axis, and a lower portion formed on a surface of the piezoelectric element that faces the surface of the substrate An electrode, and the piezoelectric element is bonded to the substrate surface by electrically connecting the lower electrode with a conductive adhesive provided on the inner side of the peripheral edge of the piezoelectric element. The substrate is adhered to the substrate surface by an insulating underfill material provided around the adhesive.

  An optical scanner according to a second aspect is the optical scanner according to the first aspect, wherein the underfill material is provided over the entire outer periphery of the piezoelectric element.

  The optical scanner according to claim 3 is the optical scanner according to claim 2, wherein the underfill material has an outer periphery of the piezoelectric element so as to form a space between the piezoelectric element and the substrate surface. It is provided over the entire circumference of the part.

  Furthermore, the optical scanner according to claim 4 is the optical scanner according to any one of claims 1 to 3, wherein the conductive adhesive is a predetermined amount at a plurality of locations on the substrate surface facing the lower electrode. It is characterized by being applied one by one.

  In the optical scanner according to the first aspect, the lower electrode is electrically connected to the substrate and bonded to the piezoelectric element by the conductive adhesive provided inside the peripheral portion of the piezoelectric element. Thereby, it can prevent that a conductive adhesive protrudes from the outer peripheral part of a piezoelectric element, and can prevent reliably the short circuit with the upper electrode of a piezoelectric element and a lower electrode by a conductive adhesive. In addition, since the underfill material is insulative, even if the underfill material provided around the conductive adhesive protrudes from the outer peripheral portion of the piezoelectric element, the upper and lower electrodes of the piezoelectric element by the underfill material Can be reliably prevented. Further, since this piezoelectric element is bonded to the substrate surface by an insulating underfill material provided between the piezoelectric element and the substrate surface and a conductive adhesive, the piezoelectric element is bonded to the substrate. By increasing the area, the driving efficiency of the piezoelectric element can be improved.

  In the optical scanner according to claim 2, the underfill material is provided over the entire circumference of the outer peripheral portion of the piezoelectric element, so that the lower electrode of the piezoelectric element is covered with the conductive adhesive and the underfill material over the entire surface. It becomes possible to adhere on the substrate, and the drive efficiency of the piezoelectric element can be further improved.

  In the optical scanner according to the third aspect, the underfill material is provided over the entire circumference of the outer peripheral portion of the piezoelectric element so as to form a space between the piezoelectric element and the substrate surface. The amount of the underfill material used can be reduced while improving the driving efficiency.

  Furthermore, in the optical scanner according to claim 4, since the conductive adhesive is applied in a predetermined amount to a plurality of locations on the substrate surface facing the lower electrode of the piezoelectric element, the tilt of the piezoelectric element with respect to the substrate surface is prevented. In addition to being able to bond, the amount of conductive adhesive used can be reduced.

1 is a plan view schematically showing a schematic configuration of an optical scanner according to Embodiment 1. FIG. It is X1-X1 arrow sectional drawing of FIG. FIG. 6 is an explanatory diagram illustrating a method for manufacturing the optical scanner according to the first embodiment. It is explanatory drawing which shows an example of S1 of FIG. It is explanatory drawing which shows an example of S2 of FIG. It is explanatory drawing which shows an example of S4 of FIG. It is a figure which shows an example of the rocking drive of a reflective mirror part. It is a table | surface which shows an example of the deflection angle of a reflective mirror part at the time of adhere | attaching a piezoelectric element only with the conductive adhesive from which an elasticity modulus differs. It is a figure which shows the correlation with the elasticity modulus and deflection angle of the conductive adhesive of FIG. It is a figure which shows the correlation with the adhesion area of a conductive adhesive, and a deflection angle at the time of adhere | attaching only with a conductive adhesive, and when adhere | attaching with a conductive adhesive and an underfill material. 6 is a plan view schematically showing a schematic configuration of an optical scanner according to Embodiment 2. FIG. It is X2-X2 arrow sectional drawing of FIG. It is a table | surface which shows an example of the deflection angle of a reflective mirror part at the time of adhere | attaching the peripheral part of a piezoelectric element with the underfill material from which an elasticity modulus differs. It is a figure which shows the correlation with the elasticity modulus and deflection angle of the underfill material of FIG. It is sectional drawing of the part containing the piezoelectric element of the optical scanner which concerns on other Example 1. FIG. It is a top view which shows typically schematic structure of the optical scanner which concerns on other Example 2. FIG.

It will be described in detail with reference to the drawings in Examples 1 and 2 embodying with the optical scanner according to the present invention.

[Schematic configuration of optical scanner]
First, a schematic configuration of the optical scanner 1 according to the first embodiment will be described with reference to FIGS. 1 and 2.
As shown in FIGS. 1 and 2, in the optical scanner 1, a substrate 2 having a rectangular shape in plan view is supported in a cantilevered manner by a support member 3 at a base end portion. The substrate 2 is formed by pressing or etching using a conductive material having elasticity, such as stainless steel (for example, SUS304 or SUS430), titanium, iron, or the like. The thickness of the substrate 2 is about 30 μm to 500 μm.

  The substrate 2 is formed by etching using an elastic material such as silicon, and gold (Au) is formed on the surface thereof by physical vapor deposition (PVD), vacuum deposition, sputtering, AD, or the like. Alternatively, 0.2 μm to 0.6 μm of platinum (Pt) or the like may be stacked so as to have a conductive layer on the surface.

  As shown in FIG. 1, the substrate 2 is formed with a through hole 11 having a rectangular shape in plan view through which light can pass on the free end side, along a direction perpendicular to the free end side direction. In addition, a reflection mirror portion 12 having a substantially rectangular shape in plan view, on which a reflection surface 12A is formed, is provided at the center portion of the through hole 11 so as to be symmetric with respect to the swing shaft 15 in a direction perpendicular thereto. . The reflection mirror unit 12 is not limited to a rectangle, but may be a square, a substantially square, a diamond, a polygon, a circle, an ellipse, or the like.

  The reflecting surface 12A of the reflecting mirror section 12 is swung around a swinging shaft 15 that is also a symmetrical centerline in the longitudinal direction. A pair of torsion beam portions 16A and 16B extend in opposite directions from the both side surface portions of the reflection mirror portion 12 along the swing shaft 15, and are connected to the inner side surfaces of the through holes 11 facing each other. Yes.

  Here, the reflection mirror part 12 is formed so that the longitudinal direction in the plan view is about 800 μm to 1200 μm and the short side direction (the width direction) in the plan view is about 100 μm to 500 μm. The pair of torsion beam portions 16 </ b> A and 16 </ b> B are formed so that the short side direction (width direction) in a plan view orthogonal to the swing shaft 15 is about 80 μm to 150 μm.

  Further, as shown in FIGS. 1 and 2, a sheet-like piezoelectric element 18 having a rectangular shape in plan view is provided with a conductive adhesive 20 on the base end side of the substrate 2, and a side surface portion in the longitudinal direction is a swing shaft. It is bonded so as to be parallel to 15. The upper and lower surfaces of the piezoelectric element 18 are respectively laminated with 0.2 μm to 0.6 μm of gold (Au), platinum (Pt) or the like over the entire surface to form an upper electrode 18A and a lower electrode 18B.

  The piezoelectric element 18 has a thickness of about 30 μm to 100 μm, a length in the direction of the swing shaft 15 of about 5 mm, and a length in the direction perpendicular to the swing shaft 15 of about 2.8 mm. . Further, the piezoelectric element 18 passes through the center position in the swing axis direction on the swing shaft 15 of the reflection mirror section 12 so that the center position is located on the axis line 21 orthogonal to the swing shaft 15. Is provided. Further, the conductive adhesive 20 having conductivity formed of a synthetic resin material such as epoxy, acrylic, or silicon is provided on the inner side of the peripheral edge of the piezoelectric element 18. About 30% to about 75% of the area is adhered to the surface of the substrate 2 by the conductive adhesive 20.

  And the space part which is not adhere | attached with the conductive adhesive 20 between the piezoelectric element 18 and the board | substrate 20 is synthetic | combination of epoxy type, an acrylic type, a silicon type etc. over the perimeter of the outer peripheral surface of this piezoelectric element 18. An underfill material 23 having an insulating property made of a resin material is filled and bonded. Further, as shown in FIG. 2, the underfill material 23 is provided so as to cover the entire outer peripheral surface of the piezoelectric element 18.

  Accordingly, the entire surface portion of the piezoelectric element 18 facing the substrate 2 is bonded to the surface portion of the substrate 2 by the conductive adhesive 20 and the underfill material 23. As a result, as described later, by applying an alternating voltage between the upper electrode 18A of the piezoelectric element 18 and the substrate 2, a standing wave having the oscillation shaft 15 as a node is generated on the substrate 2 and reflected. The mirror portion 12 can be swung around the swing shaft 15 (see FIG. 7).

[Manufacturing method of optical scanner]
Next, a method for manufacturing the optical scanner 1 will be described with reference to FIGS.
As shown in FIG. 3, first, in step (hereinafter abbreviated as “S”) 1, the substrate 2 in which the reflection mirror portion 12 and the torsion beam portions 16 </ b> A and 16 </ b> B are formed in the central portion of the through hole 11 is set horizontally. To do. Then, as shown in FIG. 4, on the base end side of the substrate 2, the conductive adhesive 20 is applied by a dispenser 25 at a position on the axis 21 that faces the substantially central portion of the piezoelectric element 18. The supply amount of the conductive adhesive 20 onto the substrate 2 is set so as to adhere about 30% to about 75% of the inner area from the periphery of the piezoelectric element 18 when the piezoelectric element 18 is mounted. ing.

  Then, as shown in FIG. 3, in S <b> 2, the sheet-like piezoelectric element 18 having a rectangular shape in plan view is mounted on the substrate 2 via the conductive adhesive 20. For example, as shown in FIG. 5, the sheet-like piezoelectric element 18 is adsorbed by the crimping head 27 and pressed against the substrate 2 through the conductive adhesive 20, and the center position of the piezoelectric element 18 is positioned on the axis line 21. Arrange as follows. Thereby, the conductive adhesive 20 is spread from about 30% to about 75% of the inner area from the peripheral edge of the piezoelectric element 18. Note that an upper electrode 18A and a lower electrode 18B are formed over the entire upper and lower surfaces of the piezoelectric element 18, respectively.

  Subsequently, as shown in FIG. 3, in S3, the conductive adhesive 20 is heat-cured at about 90 ° C. to about 180 ° C. Accordingly, the piezoelectric element 18 is electrically connected to the lower electrode 18B and the surface of the substrate 2, and about 30% to about 75% of the inner area from the peripheral edge is bonded onto the substrate 2.

  Thereafter, in S <b> 4, the underfill material 23 is applied over the entire outer periphery of the piezoelectric element 18. For example, as shown in FIG. 6, the underfill material 23 is applied around the outer peripheral portion of the piezoelectric element 18 while being applied by a dispenser 26, and an underfill is made between the piezoelectric element 18 and the substrate 2 using a capillary phenomenon. The material 23 is filled. The underfill material 23 is applied at a time from a plurality of locations on the outer periphery of the piezoelectric element 18 by a plurality of dispensers 26, and the underfill material 23 is applied between the piezoelectric element 18 and the substrate 2 by utilizing capillary action. You may make it fill.

And as shown in FIG. 3, in S5, the underfill material 23 is heat-hardened at about 100 degreeC-about 130 degreeC. Thereby, the entire surface of the piezoelectric element 18 is bonded to the surface portion of the substrate 2 by the conductive adhesive 20 and the underfill material 23.
Thereafter, in S6, the base end side of the substrate 2 is attached to the support member 3 in a cantilever manner. In S 7, a wire voltage is bonded to the surface portion of the substrate 2 and the upper electrode 18 A of the piezoelectric element 18 so that a driving voltage can be applied to the piezoelectric element 18.

[Oscillation drive]
Next, the swing drive of the optical scanner 1 will be described with reference to FIG.
As shown in FIG. 7, a predetermined drive voltage (for example, an alternating voltage having an amplitude of about 10 V and a bias voltage of about 10 V is added to the substrate 2 and the upper electrode 18A of the piezoelectric element 18 via a drive circuit 31. Apply). As a result, the piezoelectric element 18 bonded on the substrate 2 is displaced in the direction orthogonal to the application direction, that is, in the direction of the axis 21 orthogonal to the swing shaft 15.

  Then, due to the displacement of the piezoelectric element 18, the substrate 2 has the base end portion on the support member 3 side as a fixed end, and depending on whether the displacement of the piezoelectric element 18 is upward or downward, the free end on the through hole 11 side is It is displaced in the same direction as the piezoelectric element 18 upward or downward. Thereby, by setting the drive mode of the piezoelectric element 18 to the torsional resonance state, it is possible to generate a standing wave having the swing shaft 15 as a node on the substrate 2.

  Further, the standing wave having the swing shaft 15 as a node can act on the reflecting mirror portion 12 in a horizontal state supported by the torsion beam portions 16A and 16B to apply a force that gives a rotational moment. Induces torsional vibration. As a result, the reflection mirror unit 12 is swung at a swing angle θ around the swinging shaft 15 that is the axis of each of the torsion beam portions 16A and 16B. Further, since the oscillating shaft 15 is located at this standing wave node, it does not move in any direction.

[Example of driving only with conductive adhesive]
Here, about 75% of the area of the piezoelectric element 18 is adhered to the surface of the substrate 2 with the conductive adhesive 20, and the reflection mirror portion with respect to the elastic modulus of the various conductive adhesives 20 when the underfill material 23 is not used. An example of the swing angle θ around the 12 swing shafts 15 will be described with reference to FIGS.

  The deflection angle table 35 shown in FIG. 8 adheres about 75% of the area of the piezoelectric element 18 to the surface of the substrate 2 with each of the conductive adhesives A to G, and does not use the underfill material 23. This is a measured value of the deflection angle of the reflecting mirror unit 12 in a torsional resonance state when driven. In addition, a drive voltage obtained by adding a bias voltage of about 10 V to an alternating voltage having an amplitude of about 10 V was applied to the piezoelectric element 18.

  The deflection angle table 35 includes a “conductive adhesive” indicating the type of the conductive adhesive 23, a “conductive adhesive elastic modulus” indicating the elastic modulus of the conductive adhesive 23, and the conductive adhesive. 23 represents the deflection angle θ of the reflection mirror portion 12 in the torsional resonance state when about 75% of the area of the piezoelectric element 18 is bonded to the substrate 2 and the piezoelectric element 18 is driven without using the underfill material 23. It consists of “runout angle”.

  For example, the “conductive adhesive” of the deflection angle table 35 is “A” and the “elastic modulus” is “6.4 Gpa”. The reflection in the torsional resonance state when about 75% of the area of the piezoelectric element 18 is adhered to the substrate 2 with the conductive adhesive “A” and the piezoelectric element 18 is driven without using the underfill material 23. The deflection angle θ of the mirror unit 12 is “23 deg”.

Next, the correlation between the “elastic modulus” of each of the conductive adhesives A to G of the deflection angle table 35 and the “swing angle” of the reflection mirror unit 12 will be described with reference to FIG.
In the correlation diagram 36 of the elastic modulus and the deflection angle of the conductive adhesive shown in FIG. 9, the vertical axis represents the “deflection angle” (deg) of the reflection mirror portion 12, and the horizontal axis represents the elastic modulus ( Gpa). And the data of "elastic modulus" and "swing angle" of each conductive adhesive AG of the deflection angle table 35 shown in FIG. 8 is plotted.

  Therefore, as shown in FIG. 9, about 75% of the area of the piezoelectric element 18 is adhered to the surface of the substrate 2 by the conductive adhesive 20, and even when the underfill material 23 is not used, the conductive adhesive 20 If the elastic modulus is about 4 Gpa or more, the deflection angle of the reflection mirror unit 12 in the torsional resonance state is considered to be about 20 deg to about 23 deg. Furthermore, when the elastic modulus of the conductive adhesive 20 is about 6 Gpa ± 0.5 Gpa, the deflection angle of the reflection mirror portion 12 in the torsional resonance state is considered to be the maximum angle.

[Driving example using underfill material]
Next, the “adhesive area ratio” and twist of the conductive adhesive 20 when the piezoelectric element 18 is bonded only by the conductive adhesive 20 and when the piezoelectric element 18 is bonded by the conductive adhesive 20 and the underfill material 23. The correlation with the “deflection angle” of the reflection mirror unit 12 in the resonance state will be described with reference to FIG. In addition, a drive voltage obtained by adding a bias voltage of about 10 V to an alternating voltage having an amplitude of about 10 V was applied to the piezoelectric element 18.

  In the correlation diagram 37 of the bonding area ratio and the deflection angle shown in FIG. 10, the vertical axis indicates the “deflection angle” (deg) of the reflection mirror unit 12 in the torsional resonance state, and the horizontal axis indicates the conductive adhesive of the piezoelectric element 18. The ratio (%) of the adhesion area by 20 is taken. The data of the black triangle mark shows that about 35% of the area of the piezoelectric element 18 is bonded with the conductive adhesive A (see FIG. 8) having an elastic modulus of “6.4 Gpa”, and the underfill material 23 is not used. The data value indicates that the deflection angle θ of the reflection mirror portion 12 in the torsional resonance state when the piezoelectric element 18 is driven is “11.9 deg”.

  Further, the black square data shows that about 75% of the area of the piezoelectric element 18 is bonded with the conductive adhesive A having an elastic modulus of “6.4 Gpa”, and the piezoelectric element 18 is bonded without using the underfill material 23. This is a data value indicating that the deflection angle θ of the reflecting mirror unit 12 in the torsional resonance state when driven is “23 deg”.

  The data with black circles indicates that about 75% of the area of the piezoelectric element 18 is bonded with the conductive adhesive A having an elastic modulus of “6.4 Gpa”, and further, the entire circumference of the outer peripheral portion of the piezoelectric element 18 is covered. When the underfill material F1 (see FIG. 13) with an elastic modulus of “4.1 Gpa” is filled and bonded, the deflection angle θ of the reflection mirror portion 12 in the torsional resonance state is “27.3 deg”. This is the data value shown. That is, as is clear from the data of the black circles, an area of about 75% inside the peripheral portion of the piezoelectric element 18 is bonded with the conductive adhesive A having an elastic modulus of “6.4 Gpa”, and further, the piezoelectric element By bonding the area of the peripheral part of the remaining 18% with the underfill material F1 having an elastic modulus of “4.1 Gpa”, the deflection angle of the reflection mirror part 12 in the torsional resonance state is increased by “4.3 deg”. I was able to.

  Therefore, as shown in FIG. 10, about 75% of the area of the piezoelectric element 18 is bonded with the conductive adhesive 20, and about 25% of the area of the piezoelectric element 18 around the conductive adhesive 20 is undercoated. By applying and adhering the fill material 23, it is considered that the driving efficiency of the piezoelectric element 18 can be improved and the deflection angle of the reflection mirror portion 12 in the torsional resonance state can be increased.

  As described above, in the optical scanner 1 according to the first embodiment, the piezoelectric element 18 is electrically connected to the substrate 2 with the lower electrode 18B by the conductive adhesive 20 provided on the inner side of the peripheral edge of the piezoelectric element 18. Glued together. This prevents the conductive adhesive 20 from protruding from the outer peripheral portion of the piezoelectric element 18, and reliably prevents a short circuit between the upper electrode 18 </ b> A and the lower electrode 18 </ b> B of the piezoelectric element 18 due to the conductive adhesive 20. it can.

  Further, since the underfill material 23 is insulative, the short circuit between the upper electrode 18A and the lower electrode 18B of the piezoelectric element 18 due to the underfill material 23 applied over the entire circumference of the piezoelectric element 18 is reliably prevented. can do. Further, the lower electrode 18B of the piezoelectric element 18 is filled with the conductive adhesive 20 and the underfill by filling the underfill material 23 with the dispenser 26 over the entire circumference of the outer periphery of the piezoelectric element 18 by utilizing capillary action. The material 23 can be adhered onto the substrate 2 over the entire surface, and the drive efficiency of the piezoelectric element 18 can be improved.

  Furthermore, it is considered that the elastic modulus of the conductive adhesive 20 is appropriate if it is about 4 Gpa or more. Further, preferably, when the elastic modulus of the conductive adhesive 20 is about 6 Gpa ± 0.5 Gpa, it is considered that the deflection angle of the reflection mirror portion 12 in the torsional resonance state can be maximized.

Next, an optical scanner 41 according to the second embodiment will be described with reference to FIGS. In the following description, the same reference numerals as those of the optical scanner 1 according to the first embodiment shown in FIGS. 1 to 10 denote the same or corresponding parts as those of the optical scanner 1 according to the first embodiment. .
First, a schematic configuration of the optical scanner 41 according to the second embodiment will be described with reference to FIGS. 11 and 12.

  As shown in FIGS. 11 and 12, the schematic configuration of the optical scanner 41 according to the second embodiment is substantially the same as that of the optical scanner 1 according to the first embodiment. However, in the optical scanner 41 according to the second embodiment, about 20% to about 50% of the area of the piezoelectric element 18 is bonded to the surface of the substrate 2 by the conductive adhesive 20. In addition, a space 42 is formed between the underfill material 23 applied and bonded over the entire outer peripheral surface of the piezoelectric element 18 and the conductive adhesive 20.

  That is, in S1 of FIG. 3, the supply amount of the conductive adhesive 20 onto the substrate 2 by the dispenser 25 is about 20% of the inner area from the periphery of the piezoelectric element 18 when the piezoelectric element 18 is mounted. Set to adhere ~ 50%. 3, when the underfill material 23 is applied along the outer peripheral portion of the piezoelectric element 18 using the capillary phenomenon by the dispenser 26, the gap between the conductive adhesive 20 and the underfill material 23 is determined. The amount of supply of the underfill material 23 is set so as to form the space portion 42.

  Thereafter, in S5 of FIG. 3, the underfill material 23 is heated and cured at about 100 ° C. to about 130 ° C., and then the base end side of the substrate 2 is attached to the support member 3 in a cantilevered manner in S6. Then, in S7 of FIG. 3, wire driving is performed on the surface portion of the substrate 2 and the upper electrode 18A of the piezoelectric element 18 so that a driving voltage can be applied to the piezoelectric element 18.

[Oscillation drive example]
Here, about 35% of the area of the piezoelectric element 18 is adhered to the surface of the substrate 2 with the conductive adhesive 20, and various underfills when the peripheral portion of the piezoelectric element 18 is adhered with various underfill materials 23. An example of the swing angle θ around the swing axis 15 of the reflection mirror portion 12 with respect to the elastic modulus of the material 23 will be described with reference to FIGS. 13 and 14.

  The deflection angle table 45 shown in FIG. 13 adheres about 35% of the area of the piezoelectric element 18 to the substrate surface with a conductive adhesive A (see FIG. 8) having an elastic modulus of 6.4 Gpa. It is a measured value of the deflection angle of the reflection mirror part 12 in a torsional resonance state when the underfill materials F1 to F6 are applied and bonded while forming the space part 42 therebetween. In addition, a drive voltage obtained by adding a bias voltage of about 10 V to an alternating voltage having an amplitude of about 10 V was applied to the piezoelectric element 18.

  The deflection angle table 45 includes an “underfill material” that indicates the type of the underfill material 23, an “underfill material elastic modulus” that indicates the elastic modulus of the underfill material 23, and a space portion 42 formed by the underfill material 23. Are formed with a “deflection angle” representing the deflection angle θ of the reflection mirror portion 12 in a torsional resonance state when driven by bonding the peripheral edge of the piezoelectric element 18.

  For example, the “underfill material” of the deflection angle table 45 indicates that the “elastic modulus” of “F1” is “4.1 Gpa”. Then, about 35% of the area of the piezoelectric element 18 is bonded to the substrate 2 with the conductive adhesive A having an elastic modulus of 6.4 Gpa, and an underfill material of “F1” is placed between the conductive adhesive A and the space portion. It shows that the deflection angle θ of the reflection mirror portion 12 in the torsional resonance state when applied and bonded while forming 42 was “26.2 deg”.

  Here, as shown in the black triangle data in FIG. 10, about 35% of the area of the piezoelectric element 18 is bonded with the conductive adhesive A having an elastic modulus of “6.4 Gpa”, and the underfill material 23 is bonded. When the piezoelectric element 18 is driven without using, the deflection angle θ of the reflection mirror portion 12 in the torsional resonance state is “11.9 deg”.

  Further, as shown in the black circle data in FIG. 10, about 75% of the area of the piezoelectric element 18 is bonded with the conductive adhesive A having an elastic modulus of “6.4 Gpa”. When the underfill material F1 (see FIG. 13) having an elastic modulus of “4.1 Gpa” is filled and bonded over the entire circumference of the outer peripheral portion, the deflection angle θ of the reflecting mirror portion 12 in the torsional resonance state is “27”. .3 deg ".

  Thus, 35% of the area of the piezoelectric element 18 is bonded with the conductive adhesive A having an elastic modulus of “6.4 Gpa”, and the underfill material F1 having an elastic modulus of “4.1 Gpa” is further bonded to the conductive adhesive. Even if it is applied and bonded while forming the space portion 42 with A, the deflection angle θ of the reflection mirror portion 12 in the torsional resonance state is such that the entire surface of the lower electrode 18B of the piezoelectric element 18 is applied to the conductive adhesive A. It can be considered that the deflection angle θ can be made substantially the same as that when bonded with the underfill material F1.

Next, a correlation between the “elastic modulus” of each of the underfill materials F1 to F6 of the deflection angle table 45 and the “swing angle” of the reflection mirror unit 12 will be described with reference to FIG.
In the correlation diagram 46 between the elastic modulus and the deflection angle of the underfill material shown in FIG. 14, the vertical axis indicates the “deflection angle” (deg) of the reflection mirror portion 12, and the horizontal axis indicates the elastic modulus (Gpa) of the underfill material 23. Have taken. And the data of the "elastic modulus" and "swing angle" of each underfill material F1-F6 of the deflection angle table 45 shown in FIG. 13 is plotted.

  Therefore, as shown in FIG. 14, about 35% of the area of the piezoelectric element 18 is adhered to the substrate surface by the conductive adhesive A (see FIG. 8) having an elastic modulus of 6.4 Gpa. When the peripheral portion of the piezoelectric element 18 is bonded over the entire circumference with the underfill material 23 while forming the space portion 42 between them, if the elastic modulus of the underfill material 23 is 4 Gpa or more, the torsional resonance state It is considered that the deflection angle of the reflection mirror section 12 is about 24 deg to about 27 deg. That is, it is considered that the deflection angle θ can be made substantially the same as when the entire surface of the lower electrode 18B of the piezoelectric element 18 is bonded with the conductive adhesive A and the underfill material F1.

  As described above, in the optical scanner 41 according to the second embodiment, the entire area of the outer peripheral portion of the piezoelectric element 18 is formed so that the space portion 42 is formed between the piezoelectric element 18 and the surface of the substrate 2 in the underfill material 23. By applying and adhering with the dispenser 26 over the circumference, the amount of use of the underfill material 23 can be reduced while improving the driving efficiency of the piezoelectric element 18.

  In addition, this invention is not limited to the said Example 1 and Example 2, Of course, various improvement and deformation | transformation are possible within the range which does not deviate from the summary of this invention. For example, the following may be used.

[Other Example 1]
(A) An optical scanner 51 according to another embodiment 1 will be described with reference to FIG. In the following description, the same reference numerals as those of the optical scanner 41 according to the second embodiment in FIGS. 11 to 14 denote the same or corresponding parts as those of the optical scanner 41 according to the second embodiment. .

  As shown in FIG. 15, the optical scanner 51 has substantially the same configuration as the optical scanner 41 according to the second embodiment. However, in the optical scanner 51, the underfill material 23 is applied and bonded by the dispenser 26 so as to cover the entire periphery of the upper electrode 18A of the piezoelectric element 18 while forming the space 42. . Thereby, the peripheral part of the piezoelectric element 18 can be more firmly bonded to the surface of the substrate 2 over the entire circumference, and the drive efficiency of the piezoelectric element 18 can be improved.

[Other Example 2]
(B) An optical scanner 61 according to another embodiment 2 will be described with reference to FIG. In the following description, the same reference numerals as those of the optical scanner 41 according to the second embodiment in FIGS. 11 to 14 denote the same or corresponding parts as those of the optical scanner 41 according to the second embodiment. .

  As shown in FIG. 16, the optical scanner 61 has substantially the same configuration as the optical scanner 41 according to the second embodiment. However, the optical scanner 61 supplies the conductive adhesive 20 to the four locations on the surface of the substrate 2 facing the lower electrode 18B of the piezoelectric element 18 in a predetermined amount by the dispenser 25 at S1 in FIG. You may make it do. In addition, you may apply | coat to 4 or more places with the dispenser 25 at the point form.

  3, the sheet-like piezoelectric element 18 is adsorbed by the pressure-bonding head 27 and is pressed against the substrate 2 through the conductive adhesives 20 supplied in a plurality of points, and is placed on the axis 21. It arrange | positions so that the center position of the piezoelectric element 18 may be located. Subsequently, in S3 of FIG. 3, the conductive adhesive 20 is heat-cured at about 90 ° C. to about 180 ° C. Thus, the piezoelectric element 18 is electrically connected to the substrate 2 by electrically connecting the lower electrode 18B and the surface of the substrate 2 by the respective conductive adhesives 20 applied at four locations.

  After that, when applying the underfill material 23 along the outer peripheral portion of the piezoelectric element 18 using the capillary phenomenon by the dispenser 26 in S4 of FIG. 3, each of the conductive adhesives 20 and the underfill material 23 is The supply amount of the underfill material 23 is set so as to form a space 42 therebetween. In S5 of FIG. 3, the underfill material 23 is heated and cured at about 100 ° C. to about 130 ° C., and then the base end side of the substrate 2 is attached to the support member 3 in a cantilevered manner in S6. After that, in S7 of FIG. 3, wire bonding is performed to the surface portion of the substrate 2 and the upper electrode 18A of the piezoelectric element 18 so that a driving voltage can be applied to the piezoelectric element 18.

  Thereby, in the optical scanner 61, the usage-amount of the conductive adhesive 20 can be reduced by apply | coating and adhering the conductive adhesive 20 to several places in the shape of a dot. In the optical scanner 61, the underfill material 23 is applied by the dispenser 26 over the entire circumference of the outer peripheral portion of the piezoelectric element 18 so as to form a space 42 between the piezoelectric element 18 and the surface of the substrate 2. By adhering, the use amount of the underfill material 23 can be reduced while improving the driving efficiency of the piezoelectric element 18.

[Other Example 3]
(C) In S1 of FIG. 3, after applying the conductive adhesive 20 by the dispenser 25, the underfill material 23 is applied by the dispenser 26 while forming a gap at a predetermined interval around the conductive adhesive 20. May be. Then, after mounting the piezoelectric element 18 in S2 of FIG. 3, the conductive adhesive 20 and the underfill material 23 may be heat-cured at about 100 ° C. to about 130 ° C. in S3 of FIG. . As a result, the processing steps S4 and S5 in FIG. 3 can be omitted, and the work efficiency can be improved.

DESCRIPTION OF SYMBOLS 1, 41, 51, 61 Optical scanner 2 Board | substrate 3 Support member 11 Through-hole 12 Reflection mirror part 15 Oscillation shaft 16A, 16B Twist beam part 18 Piezoelectric element 18A Upper electrode 18B Lower electrode 20, AG Conductive adhesive 23 , F1 to F6 Underfill material 25, 26 Dispenser 31 Drive circuit 42 Space part

Claims (4)

In an optical scanner that scans light in a predetermined direction by driving the mirror unit around a swing axis,
A substrate having conductivity on the surface and supporting the mirror part so as to be swingable;
A piezoelectric element that is bonded to the surface of the substrate and swings the mirror portion around a swing axis;
A lower electrode formed on a surface of the piezoelectric element facing the surface of the substrate;
With
The piezoelectric element is attached around the conductive adhesive while the lower electrode is electrically connected to the substrate surface by a conductive adhesive provided on the inner side of the periphery of the piezoelectric element. An optical scanner which is adhered to the surface of the substrate by an underfill material having an insulating property.   The optical scanner according to claim 1, wherein the underfill material is provided over the entire outer periphery of the piezoelectric element.   The underfill material is provided over the entire circumference of the outer peripheral portion of the piezoelectric element so as to form a space between the piezoelectric element and the substrate surface. Optical scanner.   4. The optical scanner according to claim 1, wherein the conductive adhesive is applied in a predetermined amount to a plurality of locations on the surface of the substrate facing the lower electrode.

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