JP2007268374A - Vibration element, manufacturing method of vibration element, optical scanner, image forming apparatus and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration element having constitution capable of surely dissolving a warp due to stress, an optical scanner provided with the vibration element, and an image display device provided with them. <P>SOLUTION: The vibration element comprises a first support part 19d supporting a vibration part 19a so as to vibrate it, and a second support part 19e1 provided with a driving layer 30 for vibrating the vibration part 19a and supporting the vibration part 19a to a substrate 19e through the first support part 19d. The second support part 19e1 has a recessed part 19f recessed over the entire width in the vibration axis direction of the vibration part 19a at a part adjacent to the first support part 19d, cross-sectional rigidity in the recessed part 19f becomes low differently from the other parts especially for a reduced cross-sectional shape, and thus the influence of the stress in the driving layer 30 provided in the second support part 19e1 is prevented from being extended to the first support part 19d. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes, for example, a vibration element used for laser beam scanning or the like, in particular, a vibration element that vibrates by an actuator such as a piezoelectric element, a method for manufacturing such a vibration element, an optical scanning device including such a vibration element, and such an optical scanning device. The present invention relates to an image forming apparatus, and an image display apparatus provided with such an optical scanning device or an image forming apparatus.

  Conventionally, as a configuration for vibrating a mirror used for scanning with laser light, a vibrating portion such as a mirror formed by applying micromachining technology is supported by a beam so as to be vibrated, and an actuator such as a piezoelectric element is used. A vibration element that vibrates a vibration part via a beam is known (for example, Patent Document 1). The vibration in this case means reciprocating rotation (swing) about the axis of the beam.

  In the case of an actuator that deforms itself, such as a piezoelectric element, it is common to generate a driving force that vibrates in the direction of reciprocating rotation of a mirror that is a vibrating part by expanding and contracting itself. The scanning of the light is enabled by vibrating the vibration part which is a mirror surface.

  FIG. 11 is a plan view for explaining a configuration in which a vibration unit using a mirror or the like is vibrated using a piezoelectric element as a vibration driving layer.

  In the figure, the mirror 100 is arranged at the center of the extension direction of the torsion beam 101 corresponding to the first support portion, and is in a direction perpendicular to the extension direction of the torsion beam 101 in a plan view, in other words, the torsion beam 101. It is rotatably supported as a center.

  The torsion beam 101 has an axial end corresponding to the extending direction branched into a bifurcated shape and integrated with the substrate 103, and the bifurcated branched portion corresponds to the second support portion 101A. A piezoelectric element 102 serving as a driving layer is disposed in FIG.

  In this configuration, the mirror 100 is made to reciprocate in the torsion beam 101 by alternately bending one of the second support portions 101A due to the electrostriction phenomenon when the energization switching to the piezoelectric element 102 is performed. It is designed to vibrate.

It is known that such a scanning device is incorporated in a scanning optical system in the above-described optical scanning device or image display device (for example, Patent Document 1).
JP 2005-148459 A

  By the way, in the scanning device to which the micromachining technology is applied, warpage may occur along the extending direction (longitudinal direction) of the beam portion due to residual stress at the time of actuator film formation or stress generated when the actuator is driven. Are known.

  For this reason, even if it vibrates at a predetermined frequency, there has been a problem that the optical path changes due to the diffusion of the scanning light due to warpage and the like, and proper scanning light positioning cannot be performed.

  In view of the problems in the above-described conventional optical scanning device using a vibration element and an image display apparatus equipped with the same, the vibration element having a configuration capable of reliably eliminating warping due to stress and scanning using the vibration element are provided. Another object of the present invention is to provide an optical scanning device, an image display device, and an image display device that can prevent deterioration in positioning accuracy.

  In order to achieve this object, the invention according to claim 1 is provided with a first support part that supports the vibration part so as to vibrate, and a drive layer that vibrates the vibration part, and the vibration is transmitted through the first support part. A second support part that supports the part on a substrate, and the second support part is recessed in a portion adjacent to the first support part over the entire width in the vibration axis direction of the vibration part. It is characterized by having a recess.

  In the present invention, since the concave portion that is depressed over the entire width in the vibration axis direction is provided in the portion adjacent to the first support portion, the sectional rigidity at that portion is different from the other portions, and the sectional shape is particularly reduced. By reducing the cross-sectional rigidity, it is possible to prevent the influence of the stress in the drive layer provided in the second support portion from reaching the first support portion.

  The invention according to claim 2 is characterized in that the first support portion is paired so as to sandwich the vibration portion.

  In the present invention, since the first support portion has a symmetrical arrangement relationship with the vibration portion interposed therebetween, the vibration in the vibration portion is favorably performed without causing deviation (vibration unevenness).

  The invention described in claim 3 is characterized in that the second support portion is paired so as to sandwich the first support portion.

  In the present invention, since the first vibrating part is arranged in a pair so as to sandwich the second vibrating part, the support characteristics are balanced so that the vibration in the vibrating part is not biased. Good vibration.

  The invention according to claim 4 is characterized in that the recess has a curved surface in a cross section perpendicular to the vibration axis.

  In the present invention, since the curved surface is formed in the concave portion, the stress concentration portion in the concave portion can be eliminated.

  According to a fifth aspect of the present invention, the concave portion has a surface in a cross section perpendicular to the vibration axis, and a wide angle with respect to the plane on both sides of the plane parallel to the extending direction of the second support portion and the plane. It has the inclined surface to make, It is characterized by the any one of Claims 1-3 characterized by the above-mentioned.

  In the present invention, since the concave portion has an inclined surface that forms a wide angle with respect to the plane parallel to the extending direction of the second support portion, the stress strain to the vibration portion can be increased by taking a large range of different rigidity. Can be suppressed satisfactorily.

  The invention according to claim 6 is characterized in that the drive layer is formed at a non-overlapping position of the second support part with respect to the position of the recess.

  In the present invention, since the drive layer does not overlap with the recess, the vibration displacement in the drive layer is prevented from concentrating on a part of the recess and the deformation of the vibration portion is suppressed to prevent vibration unevenness and the like. be able to.

  The invention according to claim 7 is characterized in that the drive layer is formed at a position including the entire arrangement position of the concave portion of the second support portion.

  In the present invention, since the driving layer has a relationship including the entire arrangement position of the concave portion in the second support portion, it is possible to avoid the vibration displacement in the driving layer from concentrating on a part of the concave portion and to deform the vibrating portion. Can be suppressed.

  The invention according to claim 8 is characterized in that the drive layer is formed on a surface of the second support portion on the side having the recess.

  The drive layer is formed on the surface having the recess in the second support portion, whereby the recess and the drive layer can be easily positioned.

  The invention according to claim 9 is characterized in that the drive layer is formed on a surface of the second support portion opposite to the side having the recess.

  In the present invention, the driving layer is formed on the surface of the second support portion on the side opposite to the concave portion, so that the stress concentration on the concave portion can be reduced and the vibration at the vibrating portion can be favorably performed.

  The invention according to claim 10 is characterized in that the driving layer is a piezoelectric element.

  In the present invention, a stable vibration can be performed by using a piezoelectric element as a drive layer.

  The invention described in claim 11 is characterized in that the recess is formed by an etching process.

  In the present invention, in the present invention, portions having different cross-sectional rigidity can be formed only by using an existing construction method, so that an increase in processing cost can be suppressed.

  The invention according to claim 12 is a manufacturing method including a support part forming step which is performed in parallel with the etching process so as to include the etching process and forms the first support part and the second support part. It is characterized by being.

  In the present invention, the time required for the forming step can be shortened by performing the supporting portion forming step in parallel with the etching process, and the forming process can be executed simply.

  A thirteenth aspect of the invention is characterized in that the manufacturing method includes a driving layer forming step of forming the driving layer on the second supporting portion after the supporting portion forming step.

  In the present invention, the formation of the drive layer can be stabilized.

  A fourteenth aspect of the present invention is an optical scanning device that includes the resonator element according to any one of the first to eleventh aspects, and performs scanning by reflecting the light beam by the vibration unit swinging a reflection surface. It is characterized by being.

  In the present invention, the vibration characteristics of the reflecting surface can be improved by preventing the vibration part from being deformed, and the optical scanning accuracy can be improved.

  A fifteenth aspect of the invention is an image forming apparatus that includes the optical scanning device according to the fourteenth aspect and forms an image by scanning a light beam according to an image signal by the optical scanning device. .

  In the present invention, the optical scanning device having the above-described effects is provided, the positioning accuracy of the scanning light can be ensured, and the accuracy of image formation can be improved.

  According to a sixteenth aspect of the present invention, the optical scanning device according to the fourteenth aspect or the image forming device according to the fifteenth aspect is provided, and the optical scanning device forms an image by scanning a light beam according to an image signal. The optical scanning type image display device projects and displays the image.

  In the present invention, the optical scanning device or the image forming device having the above-described effects is provided, the positioning accuracy of the scanning light can be improved, and the accuracy of image display can be improved.

  The invention described in claim 17 is a retinal scanning image display device that projects and displays the image on the retina of the eye.

  In the present invention, the positioning accuracy of the scanning light at the time of projection display on the retina can be improved, and a good image can be displayed.

  The invention described in claim 18 is a head-mounted image display device mounted on the observer's head.

  In the present invention, it is possible to improve the positioning accuracy of scanning light during image display and display a good image.

  According to the present invention, the thickness is different from the other parts as a configuration capable of reducing the influence of stress from the second support part having the vibration drive layer with respect to the first support part supporting the vibration part. Accordingly, since the concave portion having a different cross-sectional rigidity from that of the other portion is provided, it is possible to prevent the vibration characteristics at the vibrating portion from deteriorating without being affected by the stress on the vibrating portion.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[Configuration of image display device]
Hereinafter, an image display apparatus according to an embodiment of the present invention will be described with reference to the drawings. First, the configuration of a retinal scanning display 1 as a retinal scanning image display apparatus that is an example of an image display apparatus according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, the retinal scanning display 1 is provided with a light source unit 2. The light source unit 2 is provided with a video signal supply circuit 3 that generates each signal as an element for synthesizing video based on an external video signal, and this video signal supply circuit 3 To output a video signal 4, a horizontal synchronizing signal 5, and a vertical synchronizing signal 6.

  The light source unit 2 receives laser light whose intensity is modulated based on the red (R), green (G), and blue (B) video signals transmitted as the video signal 4 from the video signal supply circuit 3. An R laser driver 10, a G laser driver 9, and a B laser driver 8 for driving the R laser 13, the G laser 12, and the B laser 11 as light sources are provided so as to emit light.

  The light source unit 2 is combined with a collimating optical system 14 provided so as to collimate the laser light emitted from each laser, and a dichroic mirror 15 that combines the collimated laser lights. A fiber coupling optical system 16 for guiding the laser light to the optical fiber 17 is provided.

  Note that a semiconductor laser such as a laser diode or a solid-state laser may be used as the R laser 13, the G laser 12, and the B laser 11. The light source unit 2 in the present embodiment corresponds to an example of a modulation unit that modulates the intensity of light beams emitted from the R laser 13, the G laser 12, and the B laser 11 as light sources according to an image signal. Here, when a semiconductor laser is used for each light source, the intensity is directly modulated, and when a solid-state laser is used, an intensity modulator using an acoustooptic effect is included.

  Further, the retinal scanning display 1 uses an optical system 18 that receives the emitted laser light propagated from the light source unit 2 and the laser light guided by the optical system 18 in the horizontal direction using the galvano mirror 19a. A horizontal scanning system 19 as a first scanning system for scanning, a first relay optical system 20 for guiding laser light scanned by the horizontal scanning system 19 to a vertical scanning system 21 as a second scanning system, and a horizontal scanning system The vertical scanning system 21 that scans the laser light that has been scanned 19 and entered through the first relay optical system 20 in the vertical direction using the galvano mirror 21a, and the laser light that has been scanned by the vertical scanning system 21 And a second relay optical system 22 that leads to the pupil 24 of the observer.

  The first relay optical system 20 has convex lenses 41 and 42, and the second relay optical system 22 has convex lenses 51 and 52. The convex lens 41 and the convex lens 42 have the same optical power. The convex lens 51 and the convex lens 52 have the same optical power.

  The first relay optical system 20 is conjugated with the galvano mirror 19a of the horizontal scanning system 19 and the galvano mirror 21a of the vertical scanning system 21, and the second relay optical system 22 is connected with the galvano mirror 21a. Each of them is provided so as to be conjugate with the pupil 24 of the person.

  The horizontal scanning system 19 is an optical system that performs horizontal scanning (an example of primary scanning) in which a laser beam is scanned in the horizontal direction for each frame of an image to be displayed. The horizontal scanning system 19 includes a galvano mirror 19a that performs horizontal scanning, and a horizontal scanning control circuit 19c that controls driving of the galvano mirror 19a.

  On the other hand, the vertical scanning system 21 is an optical system that performs vertical scanning (an example of secondary scanning) in which the laser beam horizontally scanned by the horizontal scanning system 19 is vertically scanned in the vertical direction. The vertical scanning system 21 includes a galvano mirror 21a that scans a laser beam in the vertical direction, and a vertical scanning control circuit 21c that controls driving of the galvano mirror 21a.

  Therefore, the horizontal scanning system 19 and the vertical scanning system 21 perform scanning in a direction crossing each other.

  The horizontal scanning system 19 and the vertical scanning system 21 are connected to the video signal supply circuit 3 and scan the laser beam in synchronization with the horizontal synchronization signal 5 and the vertical synchronization signal 6 output from the video signal supply circuit 3, respectively. Is configured to do.

  The horizontal scanning system 19 and the vertical scanning system 21 in this embodiment are an example of an optical scanning device that scans an incident light beam in a primary direction and a secondary direction substantially perpendicular to the primary direction.

  Next, a process from when the retinal scanning display 1 according to the embodiment of the present invention receives an image signal from the outside to when an image is projected on the retina of the observer will be described with reference to FIG.

  As shown in FIG. 1, in the retinal scanning display 1 of the present embodiment, when the video signal supply circuit 3 provided in the light source unit 2 receives an external video signal, the video signal supply circuit 3 A video signal 4 including an R video signal, a G video signal, and a B video signal, a horizontal synchronizing signal 5 and a vertical synchronizing signal 6 for controlling the laser light output of each color of red, green, and blue are output. The R laser driver 10, the G laser driver 9, and the B laser driver 8 respectively drive the R laser 13, the G laser 12, and the B laser 11 based on the input R video signal, G video signal, and B video signal. Output a signal. Based on this drive signal, the R laser 13, the G laser 12, and the B laser 11 each generate intensity-modulated laser light and output each to the collimating optical system 14. The video signal supply circuit 3 controls the timing of generating laser light and outputting each to the collimating optical system 14 in accordance with a BD signal (not shown) indicating a driving state of a galvano mirror 19a described later. That is, such a retinal scanning display 1 (video signal supply circuit 3) controls the timing at which the galvano mirror 19a or the like emits a light beam. The generated laser light is collimated into parallel light by the collimating optical system 14, and further, is incident on the dichroic mirror 15 to be combined into one light beam. 17 to be incident.

  Laser light propagated by the optical fiber 17 is guided from the optical fiber 17 by the optical system 18 and emitted to the horizontal scanning system 19. The emitted laser light is incident on a deflection surface 19b as a reflection surface of the galvanometer mirror 19a of the horizontal scanning system 19. The laser beam incident on the deflecting surface 19b of the galvano mirror 19a is scanned in the horizontal direction in synchronization with the horizontal synchronizing signal 5, and is deflected as a reflecting surface of the galvano mirror 21a of the vertical scanning system 21 via the first relay optical system 20. Incident on the surface 21b. In the first relay optical system 20, the deflection surface 19b of the galvanometer mirror 19a and the deflection surface 21b of the galvanometer mirror 21a are adjusted so as to have a conjugate relationship. The galvano mirror 21a is reciprocally oscillating so that the deflection surface 21b changes the horizontal emission angle of the incident light in synchronization with the vertical synchronization signal 6 in the same manner as the galvano mirror 19a synchronizes with the horizontal synchronization signal 5. The laser light is scanned in the vertical direction by the galvanometer mirror 21a. Laser light that is two-dimensionally scanned in the horizontal and vertical directions by the horizontal scanning system 19 and the vertical scanning system 21 is provided so that the deflection surface 21b of the galvano mirror 21a and the pupil 24 of the observer have a conjugate relationship. The second relay optical system 22 is incident on the observer's pupil 24 and projected onto the retina. The observer can thus recognize the image by the laser light that is two-dimensionally scanned and projected onto the retina. The names of the galvanometer mirror 19a of the horizontal scanning system 19 and the galvanometer mirror 21a of the vertical scanning system 21 have been described in the same way. However, the reflection surface (deflection surface) of the galvanomirror 21a of the vertical scanning system 21 changes its angle so as to scan light. In this embodiment, the detailed configuration will be described later, but the piezoelectric drive system using a piezoelectric layer as a drive layer is used to shake the galvanometer mirrors 19a and 21a. A configuration that defines an angle (oscillation angle) is used. However, the drive method for inducing an angle change (peristalsis, rotation, etc.) for scanning by the galvanometer mirrors 19a and 21a is not limited to this, and includes a resonance type, a non-resonance type, electromagnetic drive, electrostatic drive, and the like. .

The retinal scanning display 1 is a head-mounted image display device that is also called a head-mounted display, which is mounted on an observer's head. For example, the retinal scanning display 1 is mounted on a housing (not shown) such as a glasses shape, a goggle shape, or a helmet shape. It is mounted on the observer's head.
[Configurations of various optical systems]
As described above, the configuration of various optical systems that guide the beam emitted from the optical fiber 17 to the pupil 24 of the observer while scanning two-dimensionally will be described.

  The galvanometer mirror 19a is driven to rotate about an axis extending in the vertical direction, and the beam light incident from the optical system 18 is reflected by the deflecting surface 19b to be scanned and emitted in the vertical direction. It leads to the relay optical system 20.

  The galvanometer mirror 21a is rotated around an axis extending in the horizontal direction, and the beam light incident from the first relay optical system is reflected by the deflecting surface 21b to be scanned and emitted in the horizontal direction. It will lead to the second relay optical system 22.

Next, the drive structure of the galvanometer mirrors 19a and 21a in this embodiment will be described.
In this embodiment, the horizontal scanning system 19 and the vertical scanning system 21 are optical scanning devices provided with galvanometer mirrors 19a and 21a, respectively. The retinal scanning display 1 includes an image forming apparatus that forms an image by scanning a beam corresponding to an image signal in a two-dimensional direction with the optical scanning device, and the image is placed on the retina of the eye. Projects and displays an image.

  The galvanometer mirrors 19a and 21a used in the present embodiment are integrated with a vibration element to which micromachining technology is applied.

  FIG. 2 is a diagram illustrating a configuration of a vibration element 300 for vibrating the galvanometer mirrors 19a and 21a illustrated in FIG. In the following description, for the sake of convenience, the galvanometer mirror denoted by reference numeral 19a in FIG. 1 will be described as an object. However, it is prefaced that the galvanometer mirror denoted by reference numeral 21a has the same configuration.

  2A shows the deflection surface 19b side of the vibration element 300, FIG. 2B shows the back surface side opposite to the mirror surface, and FIG. 2C shows the reference numeral in FIG. It is arrow sectional drawing of the direction shown by (C).

  In FIG. 2, the vibration element 300 includes a torsion beam 19d corresponding to a first support portion and a beam fixing corresponding to a second support portion in which both ends in the extending direction of the torsion beam 19d are integrally formed on the substrate 19e side. Part 19e1.

  In the torsion beam 19d, a galvanometer mirror 19a corresponding to the vibrating portion is formed at the center in the extending direction. For this reason, the torsion beams 19d are paired so as to sandwich the galvanometer mirror 19a which is a vibration part.

  The torsion beam 19d supports the galvanometer mirror 19a, which is a vibrating portion, so as to be able to vibrate by rotating in a direction perpendicular to the extending direction in plan view with the center of the cross section as a fulcrum, in other words, around the center of the cross section.

  The beam fixing portion 19e1 is integrated with the base end of the torsion beam 19d, and forms a pair by extending in the direction perpendicular to the extending direction of the torsion beam 19d with the base end of the torsion beam 19d interposed therebetween. .

  In this embodiment, the beam fixing portion 19e1 includes a base end of the torsion beam 19d and continuously extends in a direction perpendicular to the extending direction of the torsion beam 19d. 19e is integrated.

  In the beam fixing portion 19e1, a piezoelectric element 30 serving as a vibration driving layer is provided on the same side as the surface on which the deflection surface 19b is provided in the galvanometer mirror 19a, and symmetrically with the base end of the torsion beam 19d interposed therebetween. Is provided.

  As shown in FIG. 2B, the beam fixing portion 19e1 is provided with a concave portion 19f at a position adjacent to the base end portion of the torsion beam 19d.

  The concave portion 19f is a portion that makes the cross-sectional rigidity of the beam fixing portion 19e1 in which the concave portion is formed different from that of the other portions. Is low.

  For this reason, the influence of the stress distortion on the torsion beam 19d can be prevented by absorbing the influence of the stress generated in the portion where the piezoelectric element 30 is formed in the beam fixing portion 19e1 in the recess 19f. Yes.

  As shown in FIG. 2B, the concave portion 19f is formed in a direction (vibration axis) perpendicular to the vibration (reciprocal rotation) direction of the galvano mirror 19a supported by the torsion beam 19d along the width direction of the beam fixing portion 19e1. In the direction).

  The recess 19f has a rectangular cross section as shown in FIG. The recess 19f is provided on the surface opposite to the surface on which the piezoelectric element 30 is formed. Since the piezoelectric element 30 is disposed on the same side as the deflection surface 19b as described above, the recess 19f is disposed on the opposite side to the deflection surface 19b, but the piezoelectric element 30 is disposed on the opposite side to the deflection surface. In this case, the recess 19f is disposed on the same side as the deflection surface 19b.

  As shown in FIG. 3, the concave portion 19f may be disposed on the same side as the surface on which the piezoelectric element 30 is formed. In this case, since the position where the piezoelectric element 30 is formed can be determined based on the recess 19f, the position where the piezoelectric element 30 is formed can be easily determined. The piezoelectric element 30 may be disposed on the same side as the deflection surface 19b or on the opposite side.

  The shape of the recess 19f is such that the surface in the cross section perpendicular to the torsion beam 19d corresponding to the vibration axis is a plane parallel to the extending direction of the beam fixing portion 19e1 and a wide angle with respect to the plane on both sides of the parallel plane. In other words, it may be a trapezoid having a bottom portion opened on the surface side on which the piezoelectric element 30 is provided.

  In such a concave portion 19f, the bottom of the concave portion 19f, in other words, the range of different rigidity obtained by the thin-walled portion can be increased depending on the size of the plane, so that the influence of stress strain on the vibrating portion is affected. It can be suppressed well.

  Such a recess 19f is formed by wet etching, as shown in a process described later.

  FIG. 4 is a diagram showing another form of the recess 19f, and the recess 19f shown in the figure has a curved surface (surface having a radius of curvature) in a cross section perpendicular to the torsion beam 19d. In this embodiment, the bottom surface of the concave portion 19f is not a bent surface that may have a corner portion, but a substantially hemispherical shape.

  In this embodiment, since there is no corner portion where stress concentration is likely to occur inside the recess portion 19f, the stress generated in the beam fixing portion 19e1 is concentrated on a part of the recess portion 19f, so that the thin portion is formed. It is possible to prevent breakage and the like from occurring.

  3 and 4 can be provided on the surface opposite to the surface on which the piezoelectric element 30 is formed, as shown in FIG. 2, and in this case, in FIG. As shown, a positional relationship that is a non-overlapping position with respect to the arrangement position of the concave portion 19f or a relation that includes the entire arrangement position of the concave portion 19f is set as shown in FIG.

  By adopting such a positional relationship, the bending deformation caused in the piezoelectric element 30 is prevented from propagating to the corner of the concave portion 19f, thereby preventing a breakage accident due to stress concentration at the corner. ing.

  Since the present embodiment is configured as described above, the stress strain due to the influence of the stress generated at the location where the piezoelectric element 30 is formed has low cross-sectional rigidity in the recess 19f, in other words, the degree of elastic deformation. Therefore, the warping of the torsion beam 19d can be eliminated by eliminating the influence of the stress on the torsion beam 19d. As a result, it is possible to prevent the scanning light from diffusing due to deformation such as warping.

  By the way, the concave portion 19f, which is a portion having a different rigidity, has a lower bending rigidity than the other portions, and it is difficult for distortion deformation of the piezoelectric element 30 to be transmitted, and it may be a portion that causes a slow rotational vibration.

  Therefore, in the present embodiment, the thickness of the remaining thin portion of the beam fixing portion 19e1 in which the concave portion 19f is formed is set to a minimum thickness that can be propagated without causing a time delay in the rotational vibration by the piezoelectric element 30. ing.

  As a result, the rotational vibration of the torsion beam 19d through energization of the piezoelectric element 30 can be performed with a predetermined frequency without causing a time delay.

  In addition, in the above-described embodiment, the configuration in which the thickness of the cross section is different has been described as the portion having different cross-sectional rigidity.For example, instead of the concave portion, a configuration in which a material portion having a different elastic coefficient from another portion is joined. It is also possible to do.

  Further, the depth of the recess 19f is such that, as described above, the rotational vibration caused by the piezoelectric element 30 is propagated without causing a time delay, and the mechanical strength that does not cause breakage during handling in the manufacturing apparatus. It is set to a depth at which a wall thickness that can ensure the thickness is obtained. As a result, it is possible to reduce breakage accidents during manufacturing and to ensure rotational vibration at a predetermined frequency during scanning.

  FIG. 7 is a view showing a modification of the vibration element 300. The vibration element 300 shown in FIG. 7 is different in the shape of the torsion beam 19d. 7A shows a surface on the side where the piezoelectric element 30 is provided, and FIG. 7B shows a surface opposite to the surface on which the piezoelectric element 30 is provided. FIG. 7 shows the case where the deflection surface 19b is formed on the surface on which the piezoelectric element 30 is provided.

  In FIG. 7, the base end portion of the torsion beam 19d is integrally formed with the substrate 19e via a beam fixing portion 19e1 extending in a direction parallel to the extending direction of the torsion beam 19d in a manner branched in a bifurcated manner. Has been. The beam fixing portion 19e1 is integrated with the base end of the torsion beam 19d, and is paired in such a manner as to sandwich the base end of the torsion beam 19d.

  Also in this case, as in the above-described embodiment, the concave portion 19f is provided at a symmetrical position across the proximal end of the torsion beam 19d, and the shape of the concave portion 19f has a cross-sectional shape as shown in FIGS. And the positional relationship with the piezoelectric element 30 shown in FIGS. 2 to 6 is used.

  The vibration element 300 in this embodiment is manufactured based on the process shown in FIG.

  In FIG. 8, a step indicated by reference numeral (A) is a step for forming the recess 19f in the beam fixing portion 19e1, and shows a cross section corresponding to the L1-L1 cross section in FIG. In FIG. 8, the step indicated by reference numeral (B) is a step for forming the galvanometer mirror 19a, the torsion beam 19d, and the beam fixing portion 19e1, and shows a cross section corresponding to the L2-L2 cross section in FIG.

  In FIG. 8, the step of forming the concave portion 19f in the beam fixing portion 19e1 and the step of forming the torsion beam 19d are performed in parallel, and the step of forming the concave portion 19f in the beam fixing portion 19e1 is as follows. It is as follows.

  In FIG. 8, when the oxide film 70 is formed on the surface of a silicon substrate 71 used as the substrate 19 e (A-1), a lithography process using a mask (not shown) is performed after the resist 72 is applied. Then, the resist 72 is patterned (A-2). After the patterning is completed, the oxide film 70 is etched using the resist 72 as a mask (A-3). At that time, the etching of the oxide film 70 stops in the middle of the thickness direction so as not to be completely removed, that is, not to penetrate.

  After removing the resist 72, a resist 73 is applied (A-4).

  On the other hand, also in the formation part of the torsion beam 19d, the processes indicated by reference numerals (A-1) to (A-4) are performed in parallel (B-1 to B-4), and then a mask (not shown) is formed. The resist 73 other than the portions corresponding to the galvanometer mirror 19a, the torsion beam 19d, and the beam fixing portion 19e1 is removed by lithography (B-5).

  Subsequently, the oxide film 70 is etched until the surface of the silicon substrate 71 is exposed at the portion where the resist 73 is removed (B-6). In the step (B-5), when exposure is performed, the mask covers the beam fixing portion 19e1, and therefore, in the step indicated by the symbol (A-5), the mask is indicated by the symbol (A-4). State is maintained. Therefore, even when etching is performed in the step (B-6), the state indicated by the symbol (A-4) is maintained in the step indicated by the symbol (A-6).

  The resist 73 is removed when the surface of the silicon substrate 71 is exposed in the portions other than the portions where the galvanometer mirror 19a, the torsion beam 19d, and the beam fixing portion 19e1 are formed by etching (A-7, B-7).

  In this way, the removal of the other parts is progressed by etching while leaving the galvanometer mirror 19a, the torsion beam 19d, and the beam fixing portion 19e1. The etching depth of the oxide film 70 for forming the torsion beam 19d is different from the etching depth of the oxide film 70 for forming the recess 19f.

  After removing the resist, the silicon substrate 71 is etched at the portion where the surface of the silicon substrate 71 is exposed (A-8, B-8). At that time, the etching of the silicon substrate 71 is stopped in the middle of the thickness direction so as not to be completely removed, that is, not to penetrate.

  Subsequently, the oxide film 70 is etched by etching until the portion of the silicon substrate 71 corresponding to the recess 19f is exposed in the portion where the oxide film 70 remains (A-9, B-9).

  The silicon substrate 71 is etched in the portion where the surface of the silicon substrate 71 is exposed, and the silicon substrate 71 penetrates in the portion other than the portion corresponding to the recess 19f among the portions where the surface of the silicon substrate 71 is exposed. The oxide film 70 is exposed (B-10), and a recess 19f is formed in a portion corresponding to the recess 19f (A-10).

  At this time, in the portion corresponding to the recess 19f, the etching of the silicon substrate 71 is stopped in the middle of the thickness direction so that the recess 19f is formed, so that the silicon substrate 71 is not completely removed, that is, not penetrated.

  Therefore, by this etching, the necessary depth is obtained in the formation portion of the recess 19f in the etching depth, and the thickness of the silicon substrate 71 in the portions other than the formation portions of the galvano mirror 19a, the torsion beam 19d, and the beam fixing portion 19e1. A necessary shape is formed as the recess 19f, the galvano mirror 19a, the torsion beam 19d, and the beam fixing portion 19e1.

  Thereafter, all remaining oxide film 70 is removed by etching.

  Steps (A-1 to A11, B-1 to B11) are support portion forming steps for forming the torsion beam 19d as the first support portion and the beam fixing portion 19e1 as the second support portion. Yes. The support part forming step is performed so as to include an etching process (A3, A9, A10) for forming the recess 19f and in parallel with the etching process.

  The vibration element 300 formed by the process shown in FIG. 8 is a finished product by the process shown in FIG. Note that after the steps (A11, B11), both surfaces of the silicon substrate 71 excluding the formation portion of the recess 19f are oxidized.

  FIG. 10 shows a case where the concave portion 19f is provided on the same surface as the surface on which the piezoelectric element 30 is formed. In FIG. 10, the step indicated by reference numeral (C) indicates the step in the cross section indicated by reference numeral (A) in FIG. 8, and the step indicated by reference numeral (D) is indicated by reference numeral (B) in FIG. The process in a cross section is shown.

  In the figure, the piezoelectric element 30 previously configured as a drive unit assembly is bonded and integrated with the surface of the vibration element 300 where the opening side of the recess 19f is located (C-1, D-1). And the stand 301 is joined to the surface on the opposite side to the surface where the piezoelectric element 30 is located in the vibration element 300 (C-2, D-2), and the vibration element 300 is completed.

  Thus, the step (C-1) is a drive layer forming step for forming the piezoelectric element 30 on the beam fixing portion 19e1. By performing the drive layer forming step after the support portion forming step, the piezoelectric element 30 is stably and satisfactorily formed.

  An epoxy-based conductive adhesive is used at the joint between the piezoelectric element 30 and the base 301 used in the vibration element 300.

  Since the vibration element 300 is provided with the piezoelectric element 30 in a symmetrical position with respect to the extending direction center of the torsion beam 19d, the electrostriction conversion in the piezoelectric element 30 is utilized by switching the energization to the piezoelectric element 30. Thus, the torsion beam 29d can be reciprocally rotated (oscillated). As a result, the mirror surface located at the center in the longitudinal direction of the beam 19d rotates and vibrates, thereby enabling scanning.

  In addition, by providing the piezoelectric element 30 at a symmetrical position with respect to the extending direction center of the torsion beam 19d as a boundary, vibration without deviation is generated and good scanning can be performed.

  When the torsion beam 19d oscillates smoothly, the thickness of the bottom of the concave portion 19f has rigidity capable of propagating the bending deformation of the piezoelectric element 30, thereby causing smooth rotation oscillation without causing a response delay. In addition, since the distortion due to the stress remaining on the film-forming surface on the piezoelectric element 30 side is absorbed by the concave portion 19f, it is possible to maintain a state in which the torsion beam 19d is not warped, thereby scanning. Occasionally light diffusion can be reliably prevented.

  As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to such specific embodiments, and the scope of the gist of the present invention described in the scope of claims. Various modifications and changes can be made within.

  In the above-described embodiment, the beam is scanned first in the horizontal direction by the horizontal scanning system 19 and then scanned in the vertical direction by the vertical scanning system 21. However, the present invention is not limited to this. The scanning may be performed in the vertical direction by the vertical scanning system, and then scanned in the horizontal direction by the horizontal scanning system.

  Further, in the above-described embodiment, the vibration element and the optical scanning device as described above are provided, and the light beam modulated according to the image signal is scanned in the primary direction and the secondary direction by the vibration element and the optical scanning device. In the above description, a retinal scanning display (an example of a retinal scanning image display apparatus) that includes an image forming apparatus that forms an image, projects the image onto the retina of the eye, and displays the image has been described. For example, even if an image is not directly projected onto the retina of the eye, the vibration element and the optical scanning device are provided with the vibration element and the optical scanning device as described above, and the light beam modulated according to the image signal Provided with an image forming apparatus that forms an image by scanning in a primary direction and a secondary direction, and an optical scanning type image display apparatus, a display, and the like that project and display the image on a screen or the like (of the image display apparatus) The present invention may be employed as an example).

  The vibration element and optical scanning apparatus to which the present invention is applied can also be applied to a vibration element and optical scanning apparatus that scan a laser beam in an image forming apparatus such as a laser printer.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

It is a schematic block diagram which shows the retinal scanning type image display apparatus as an image display apparatus in this embodiment. It is a figure for demonstrating the structure of the vibration element in this embodiment, (A) is a top view which shows the surface by which the mirror surface is formed, (B) shows the surface on the opposite side to a mirror surface. Bottom view, (C) is a cross-sectional view in the direction indicated by the reference numeral (C) in (B). It is sectional drawing which shows another form of the recessed part formed in the vibration element shown in FIG. It is sectional drawing which shows another form of the recessed part formed in the vibration element shown in FIG. It is sectional drawing for demonstrating the arrangement | positioning relationship between a recessed part and a piezoelectric element. It is sectional drawing for demonstrating another arrangement | positioning relationship between a recessed part and a piezoelectric element. It is a figure for demonstrating the modification of a 2nd support part, (A) is a top view which shows the surface by which the mirror surface is formed, (B) is a surface on the opposite side to a mirror surface. It is a bottom view shown. It is a figure for demonstrating the manufacturing process of the vibration element in this embodiment. FIG. 9 is a schematic plan view for explaining which part of the vibration element corresponds to the process diagram shown in FIG. 8. It is a figure which shows the process for making the vibration element manufactured by the process shown in FIG. 8 into a finished product. It is a figure which shows the mirror surface side for demonstrating the prior art example of a vibration element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image display apparatus 19, 21 Optical scanning device 19a, 21a Vibrating part 19d, 21d Torsion beam 19e board | substrate 19e1 equivalent to a 1st support part 19f Recessed part 30f corresponding to a 2nd support part 30 It is used as a drive layer Piezoelectric element 300 Vibration element A1 to A11, B1 to B11 Support part forming process A3, A9, A10 Etching process for forming recess C-1, D-1 Drive layer forming process

Claims (18)

A first support part that supports the vibration part so as to vibrate;
A drive layer that vibrates the vibration part, and a second support part that supports the vibration part on a substrate via a first support part;
The second support portion is a vibration element having a recess that is recessed over the entire width in the vibration axis direction of the vibration portion at a portion adjacent to the first support portion.   The vibration element according to claim 1, wherein the first support portion is paired so as to sandwich the vibration portion.   The vibrating element according to claim 1, wherein the second support portion is paired so as to sandwich the first support portion.   The vibration element according to claim 1, wherein the concave portion has a curved surface in a cross section perpendicular to the vibration axis.   The concave portion has a surface in a cross section perpendicular to the vibration axis having a plane parallel to the extending direction of the second support portion and inclined surfaces forming a wide angle with respect to the plane on both sides of the plane. The vibration element according to claim 1, wherein the vibration element is a vibration element.   6. The vibration element according to claim 1, wherein the drive layer is formed at a non-overlapping position of the second support portion with respect to a position where the concave portion is disposed.   6. The vibration element according to claim 1, wherein the driving layer is formed at a position of the second support portion that includes the entire arrangement position of the concave portion.   The vibration element according to claim 1, wherein the drive layer is formed on a surface of the second support portion on the side having the concave portion.   The vibration element according to claim 1, wherein the driving layer is formed on a surface of the second support portion opposite to the side having the concave portion.   The vibration element according to claim 1, wherein the driving layer is a piezoelectric element.   The vibration element according to claim 1, wherein the concave portion is formed by an etching process.   The method for manufacturing a resonator element according to claim 11, wherein the support part is formed in parallel with the etching process so as to include the etching process, and forms the first support part and the second support part. A method for manufacturing a vibration element comprising a forming step.   The method for manufacturing a vibration element according to claim 12, further comprising a driving layer forming step of forming the driving layer on the second supporting portion after the supporting portion forming step.   An optical scanning device comprising the resonator element according to claim 1, wherein the vibrating unit performs scanning by reflecting a light beam by swinging a reflecting surface.   15. An image forming apparatus comprising the optical scanning device according to claim 14, wherein the optical scanning device forms an image by scanning a light beam according to an image signal.   An optical scanning device according to claim 14 or an image forming device according to claim 15, wherein the optical scanning device forms an image by scanning a light beam according to an image signal, and projects and displays the image. An image display device which is an optical scanning image display device.   The image display device according to claim 16, wherein the image display device is a retinal scanning image display device that projects and displays the image on a retina of an eye.   The image display device according to claim 16 or 17, wherein the image display device is a head-mounted image display device mounted on an observer's head.

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