JP5070869B2 - Optical scanning device and retinal scanning image display device including the same - Google Patents

Description

  The present invention relates to an optical scanning element for an optical scanner used in a laser printer or a projection display device. In particular, the present invention relates to an optical scanning element that swings a reflecting mirror by vibrating a vibrating body.

  2. Description of the Related Art Conventionally, in a projection display device or the like, an optical scanning element for scanning a laser beam modulated by an image signal to form a projected image is known. For example, rotary polygon mirrors (polygon mirrors) and vibration-driven reflectors (galvano mirrors) have been used. When using a rotating polygon mirror with a laser printer, the rotating polygon mirror that rotates at high speed is irradiated with laser light modulated by an image signal, the reflected light is scanned, and a recording medium is formed by the scanned laser light. The latent image is written on the rotating drum and transferred to paper or the like. Also, in an image display device using a vibration drive type reflecting mirror, the vibrating mirror is vibrated at high speed by a piezoelectric body or electrostatic force, and the vibrating mirror is irradiated with laser light modulated by an image signal, and the reflected light is screened. Or directly irradiate the retina to obtain an image display device. The vibration drive type reflecting mirror can reduce the size of the driving unit as compared with the rotary polygon mirror, and is suitable for a light and small optical scanning element.

  FIG. 14 is a schematic sectional view showing an optical deflector 100 used in a laser printer, a laser facsimile, or the like (see Patent Document 1). The laser beam Iin from the laser oscillator is condensed into a predetermined beam shape by the cylindrical lens 103 and is condensed on the reflecting surface of the rotating polygon mirror 101 that rotates at high speed. The laser beam reflected by the reflecting surface of the rotating polygon mirror 101 passes through the light-transmitting window 104, passes through the spherical lens 105 and the toric lens 106 having the fθ function, and rotates as a scanning light Iout by a rotating drum (not shown). The body is irradiated. The rotary polygon mirror 101 is hermetically sealed by a cover member 102 for dustproof and soundproofing measures.

Patent Document 2 describes an optical scanning device in which a vibrating mirror is formed by silicon micromachining and image recording is performed using the vibrating mirror as an optical deflector. A vibration mirror, a torsion beam that pivotally supports the vibration mirror, and a fixing portion that fixes the torsion beam are integrally formed from the silicon semiconductor substrate. The integrally formed vibrating body is attached to a fixed frame, and the periphery is covered with a cover or the like so as to secure a swinging space. This type of vibrating body vibrates at a resonance frequency determined by the moment of inertia of the vibrating mirror portion and the spring constant of the torsion beam that pivotally supports the vibrating mirror portion. However, when the oscillating mirror is thin and vibrates at a high frequency, the oscillating mirror is curved, and a focus shift of the scanned laser beam occurs. In order to correct this focus shift, a coupling lens is inserted between the laser light source and the vibration mirror, and the position of this coupling lens is moved in synchronization with the resonance frequency of the vibration mirror to correct the focus shift. It is described.
JP 2003-57586 A JP 2004-191416 A

  An optical scanning device using a rotating polyhedron that rotates at a high speed has a large volume of the optical scanning device, and it is difficult to form a compact configuration. In addition, there are problems such as high power consumption for driving the rotating polyhedron by a motor or the like, and noise generated outside because the rotating polyhedron rotates at high speed. On the other hand, the vibration drive type reflecting mirror is advantageous in that it is small in size, low power consumption, and does not generate noise, but it is desired to perform optical scanning at a higher speed, and the optical scanning device itself is downsized. There is a demand for simplification and cost reduction of the entire apparatus including an external optical system for converging an incident light beam incident on the optical scanning device and an outgoing light beam emitted from the optical scanning device.

  In the present invention, the following means have been taken in order to solve the above problems.

In the invention which concerns on Claim 1, the optical scanning part which has the vibration mirror part in which the reflective surface was formed, the support part which makes the rocking | fluctuation axis | shaft of the said vibration mirror part, and the frame part for holding the said support part And an optical scanning device that emits a reflected light beam that is scanned by reflecting an incident light beam by the oscillating mirror part that oscillates, wherein the vibration mirror part includes: The width of the rocking shaft in the axial direction is narrower than the width in the direction perpendicular to the rocking shaft, and the housing includes a transmission portion that transmits the incident light beam and the reflected light beam. The first optical element that converges the incident light beam into a cross-sectional shape corresponding to the shape of the vibrating mirror part, and the cross-sectional shape corresponding to the light beam before the reflected light beam is incident on the first optical element. A second optical element that converges in such a manner that the first light Element and the second optical element, at least, has a power with respect to the axial direction of the pivot axis, that the power with respect to the axial direction has a larger optical properties than the power with respect to the direction perpendicular to the oscillation axis The optical scanning device is characterized.

In the invention according to claim 2 , the oscillating mirror portion has a substantially polygonal or elliptical shape in which the axial direction of the oscillating shaft is a short axis and the direction orthogonal to the axial direction is a long axis. An optical scanning device according to claim 1 is provided.

In the invention according to claim 3, wherein the first optical element, according to claim 1 or claim 2 characterized in that it has a rotationally asymmetric shape with respect to the optical axis of the first optical element An optical scanning device was obtained.

According to a fourth aspect of the present invention, in the optical scanning device according to any one of the first to third aspects, the first optical element is a cylindrical lens.

The invention according to claim 5 is the optical scanning device according to any one of claims 1 to 3 , wherein the first optical element is a Fresnel lens.

The invention according to claim 6 is the optical scanning device according to any one of claims 1 to 3 , wherein the first optical element is a diffraction grating.

The invention according to claim 7 is the optical scanning device according to any one of claims 1 to 3 , wherein the first optical element is a gradient index lens.

The invention according to claim 8 is the optical scanning device according to claim 1, wherein the second optical element has an fθ characteristic with respect to a direction orthogonal to the swing axis .

The invention according to claim 9 is the optical scanning device according to claim 1, wherein the second optical element has an arc sine characteristic with respect to a direction orthogonal to the swing axis .

In the invention which concerns on Claim 10 , the said housing | casing is comprised from the accommodating part which accommodates the said optical scanning part, and the cover part for covering the said accommodating part, and the said cover part is the said permeation | transmission part and said 1st and an optical scanning apparatus according to any one of claims 1 to 9, characterized in that it is integrally formed by the optical element the same material as the.

In the invention according to claim 11, and an optical scanning apparatus according to claim 10, characterized in that it comprises the housing part and the lid part are substantially equal linear expansion coefficient.

According to a twelfth aspect of the invention, the optical scanning device according to any one of the first to eleventh aspects is provided, and a light beam modulated in accordance with an image signal is scanned by the optical scanning device and projected onto the retina. A retinal scanning image display device for display was used.

According to another aspect of the optical scanning device of the present invention, the light includes: a vibrating mirror portion having a reflecting surface; a support portion that forms a swing axis of the vibrating mirror portion; and a frame portion that holds the support portion. An optical scanning device comprising: a scanning unit; and a housing for housing the optical scanning unit, wherein the vibrating mirror unit emits a reflected light beam that is scanned by reflecting an incident light beam by the swinging vibrating mirror unit, the vibrating mirror unit Has a shape in which the width in the axial direction of the oscillating shaft is narrower than the width in the direction orthogonal to the oscillating axis, and the housing includes a transmission part that transmits the incident light beam and the reflected light beam, The transmission unit includes a first optical element that converges the incident light beam into a cross-sectional shape corresponding to a shape of the vibrating mirror unit, and a cross-sectional shape corresponding to the light beam before the reflected light beam is incident on the first optical element. A second optical element that converges to return to the first light, Element and the second optical element, at least, has a power with respect to the axial direction of the pivot axis, has a larger optical properties than the power with respect to the direction in which the power with respect to the axial direction is perpendicular to the pivot axis. Accordingly, it is possible to reduce the mass and the moment of inertia of the oscillating mirror unit, thereby increasing the scanning speed, increasing the touch angle, and reducing the power consumption. Further, since the incident light beam is converged into a shape along the shape of the vibrating mirror portion, the resolution can be improved by effectively using the area of the reflecting surface of the vibrating mirror portion. As a result, it is possible to realize a light scanning device that is light, small, low power consumption, and small in reflection loss.

According to another aspect of the optical scanning device of the present invention, the transmission unit includes a first optical element that converges the incident light beam into a cross-sectional shape corresponding to a shape of the vibration mirror unit, and the reflected light beam is a first light beam. A second optical element that converges so as to return to a cross-sectional shape corresponding to the light beam before entering the optical element, wherein the first optical element and the second optical element are at least the rocking member It has a power with respect to the axial direction of the shaft, and has an optical characteristic that the power with respect to the axial direction is larger than the power with respect to the direction orthogonal to the swing axis. As a result, the first optical element and the second optical element have a narrow width in the swing axis direction and a wide width in the direction perpendicular to the swing axis to converge the incident light beam. It is possible to effectively reduce the reflection efficiency by effectively using the surface of the vibrating mirror portion.

According to the optical scanning device of the second aspect , the oscillating mirror portion has a substantially polygonal or elliptical shape in which the axial direction of the oscillating shaft is a short axis and the direction orthogonal to the axial direction is a long axis. . As a result, the shape of the reflecting surface of the oscillating mirror unit can be matched with the shape of the incident beam converged by the first optical element, so that the weight of the oscillating mirror unit can be reduced and the reflecting surface that reflects the incident beam can be reduced. There is an advantage that an area can be secured.

According to the optical scanning device of the third aspect , the first optical element has a rotationally asymmetric shape with respect to the optical axis of the optical element. Thereby, it has the advantage that an incident light beam can be condensed along the shape of a vibration mirror part.

According to the optical scanning device of the fourth aspect , the first optical element is a cylindrical lens. As a result, the incident light beam can be converged only in the short axis direction of the vibrating mirror part with a simple configuration, and the reflection loss can be reduced by effectively using the surface area of the vibrating mirror part. Have

According to the optical scanning device of claim 5 , 6, or 7 , the first optical element is a Fresnel lens, a diffraction grating, or a gradient index lens. Thereby, there is an advantage that the thickness of the lens portion can be reduced and the entire optical scanning device can be configured compactly.

According to the optical scanning device of the eighth aspect , the second optical element has an fθ characteristic. Accordingly, there is no need to separately install an fθ lens for recording on a recording medium or the like by the emitted light beam, and thus there is an advantage that the entire apparatus can be reduced in size.

According to the optical scanning device of the ninth aspect , the second optical element has an arc sine characteristic. As a result, it is not necessary to separately install an arc sine lens for recording on a recording medium or the like by the emitted light beam, so that the entire apparatus can be reduced in size, and the projection light is substantially equalized on the projection surface of the recording medium or the like. It has the advantage that it can scan at angular velocity.

According to the optical scanning device of the tenth aspect , the housing includes the storage portion and the lid portion, and the lid portion is integrally formed of the same material as the transmission portion and the first optical element. . Accordingly, there is an advantage that a step of attaching a separate optical element to the transmission portion can be omitted, and the cost of the optical scanning device can be reduced.

According to the optical scanning device of the eleventh aspect , the storage portion and the lid portion have substantially the same linear expansion coefficient. As a result, when the ambient temperature changes, the reflection efficiency of the reflected light beam with respect to the incident light beam deteriorates due to the positional deviation between the lid part and the storage part, or the adhesive part between the cover part and the storage part is damaged. It has the advantage that it can be prevented.

According to the retinal scanning image display apparatus of the twelfth aspect , since the optical scanning apparatus is provided, there is an advantage that a lightweight and compact display apparatus can be configured.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an optical scanning unit according to an embodiment of the present invention. The optical scanning unit 1 includes a strip-shaped vibrating mirror unit 2, a supporting unit 3 that holds the vibrating mirror unit 2 from both sides and forms a swinging axis of the vibrating mirror unit 2, and transmits the swing to the supporting unit 3. Two left and right beam parts 4 having a bifurcated shape, a frame part 5 for fixing and holding the beam part 4, and four piezoelectric bodies 7a bonded and fixed across the beam part 4 and the frame part 5, 7 b, 7 c, 7 d and a fixed frame portion 6 for forming the oscillating space 9 in the oscillating mirror portion 2. Electrodes (not shown) are formed on the front and back surfaces of the piezoelectric body, and electrodes 8a to 8d are formed on the surface of the frame portion 5 and the beam portion 4 in the region where the piezoelectric bodies 7a to 7d are bonded and fixed. The electrodes formed on the back surfaces of the piezoelectric bodies 7a to 7d and the electrodes 8a to 8d on the frame portion 5 formed corresponding thereto are bonded and fixed with a conductive adhesive.

  The vibration mirror unit 2 has a shape in which the width L1 in the swing axis direction of the support unit 3 that performs torsional vibration is shorter than the width L2 in the direction perpendicular to the swing axis. Further, the surface of the vibration mirror unit 2 constitutes a reflection surface. As the reflecting surface, the material of the vibrating mirror unit 2 may be used as it is, or a metal film may be formed. By making the oscillating mirror unit 2 into a strip shape, the mass of the oscillating unit is reduced, and high-frequency resonance oscillation can be realized. The width L1 and the width L2 of the oscillating mirror unit 2 are set to a size that allows the incident light beam to be collected, and necessary resonance vibration can be obtained. For example, the width L1 of the vibration mirror unit 2 can be 300 μm, and the width L2 can be 1 mm to 1.5 mm.

  The vibration mirror unit 2 swings as follows. A high-frequency alternating voltage is applied to the electrode on the surface of the piezoelectric body 7a and the electrode 8a on the frame portion 5 below it. Thereby, the piezoelectric body 7a transmits vertical vibration to the beam portion. A high-frequency alternating voltage having a phase opposite to that of the voltage applied to the piezoelectric body 7a is applied between the electrode on the surface of the piezoelectric body 7b and the electrode 8b formed therebelow. A high-frequency alternating voltage is applied to the piezoelectric body 7c and the piezoelectric body 7d as well as the piezoelectric body 7a and the piezoelectric body 7b. As a result, torsional vibration is transmitted to the support portion 3, and the vibration mirror portion 2 is equal to the torsional resonance frequency determined by the torsional elastic coefficient of the support portion 3 and the inertia moment with respect to the swing axis of the vibration mirror portion 2. When an alternating voltage having a frequency is applied, resonance vibration of the corresponding mode is performed.

  FIG. 2 is a perspective view showing a state in which the optical scanning device 20 in which the optical scanning unit 1 is housed in a housing is disassembled. The same reference numerals are assigned to the same parts or parts having the same function. The optical scanning unit 1 is enclosed by a housing 14 including a storage unit 11 and a lid unit 10. The lid 10 is formed with a translucent transmission part 12, and the transmission part 12 is formed with a cylindrical lens 13 as a first optical element. By sealing the optical scanning unit 1 with the storage unit 11 and the lid unit 10, dust or the like enters from the outside and adheres to the vibration mirror unit 2, and the reflection efficiency of the reflection surface formed on the surface of the vibration mirror unit 2. To prevent the deterioration.

  FIG. 3 is a perspective view showing a state in which incident light is converged on the oscillating mirror 2 by the cylindrical lens 13 formed on the lid 10. The same parts or parts having the same function are denoted by the same reference numerals. The cylindrical lens 13 converges the incident incident light beam Iin having a circular cross section into a shape corresponding to the shape of the reflecting surface of the oscillating mirror unit 2. That is, the power in the axial direction of the oscillating shaft is larger than the power in the direction orthogonal thereto. The cylindrical lens 13 has a rotationally asymmetric shape with respect to its optical axis.

  The incident light beam that has passed through the cylindrical lens 13 is not converged in the Y direction orthogonal to the oscillation axis X, but is converged in the oscillation axis X direction. That is, the reflection surface of the vibration mirror unit 2 becomes the focal point of the cylindrical lens 13 with respect to the swing axis X direction. Then, when the oscillating mirror unit 2 oscillates about the oscillating axis X, the reflected light is scanned in the Y direction orthogonal to the oscillating axis X as reflected light beams Iout1, Iout2, and Iout3. . The light beam reflected from the reflecting surface of the oscillating mirror unit 2 passes through the cylindrical lens 13 and is converged to a reflected light beam having the same cross section as the incident light beam. In this way, the optical scanning device 20 scans the incident light beam Iin and converts it into scanning light such as reflected light beams Iout1, Iout2, and Iout3.

  In the present embodiment, the vibrating mirror unit 2 is formed from a silicon semiconductor substrate. That is, the vibration mirror part 2, the support part 3, the beam part 4, and the frame part 5 are integrally formed using a silicon semiconductor substrate through a photolithography process and an etching process. A thin film made of aluminum or silver is formed on the surface of the oscillating mirror 2 in order to reduce reflection loss of light. The fixed frame portion 6 on which the frame portion 5 is placed is formed of heat resistant glass provided with a swing space 9. The storage portion 11 is formed in a box shape from ceramics, and the lid portion 10 uses a light-transmitting synthetic resin to integrally form a cylindrical lens 13. Further, as the piezoelectric body 7, a sintered body made of lead zirconate titanate (PZT) was used.

  In the present embodiment, the frame portion 5, the vibration mirror portion 2, the support portion 3, and the beam portion 4 are integrally formed from a silicon semiconductor substrate. However, the vibration mirror portion is made of another metal material or the like. 2, the support part 3 and the beam part 4, and the frame part 5 may be formed separately. Further, when the silicon semiconductor substrate is integrally formed, it is not necessary to form the frame portion 5 so as to cover the periphery of the vibration mirror portion 2, and the frame portion 5 is formed only in the region where the beam portion 4 is fixed. Also good. Moreover, in the said embodiment, although the frame part 5 and the fixed frame part 6 used as the base of the frame part 5 are isolate | separated and formed, this is formed integrally from a semiconductor substrate etc., for example. Also good. In addition, it is preferable that the frame part 5 and the fixed frame part 6 use the material with substantially the same linear expansion coefficient. Therefore, in the present embodiment, a silicon semiconductor substrate is used as the frame portion 5 and heat resistant glass is used as the fixed frame portion 6.

  In the above embodiment, the bifurcated beam portion 4 is used, but the beam portion 4 can be formed in the region of the frame portion 5. That is, the support part 3 is extended to the area of the frame part 5, the fixed frame part 6 below the frame part 5 holding the support part 3 is pierced, and the frame part 5 in this pierced area is used as the beam part 4. be able to. In this case, the piezoelectric body 7 is bonded and fixed to the surface of the frame portion 5 on the boundary region between the fixed frame portion 6 that has been wound and the fixed frame portion 6 that has not been wound.

  Moreover, in the said embodiment, although the permeation | transmission part 12 and the cover part 10 which have arrange | positioned the cylindrical lens 13 were formed integrally, the cover part 10 and the permeation | transmission part 12 were made into a different body, and the permeation | transmission part 12 was changed. You may make it install in the cover part 10. FIG. Further, the lid portion 10 is installed on the upper surface of the storage portion 11, but the lid portion 10 may be installed on the side surface of the storage portion 11. In this case, it is necessary to install an optical system such as a waveguide in the storage unit 11 in order to guide the incident light beam to the vibrating mirror unit 2 of the optical scanning unit 1. In addition, it is desirable that the linear expansion coefficients of the storage unit 11, the lid unit 10, the transmission unit 12, and the cylindrical lens 13 are substantially equal. This is because, by equalizing the linear expansion coefficient, it is possible to prevent the incident light beam Iin converged by the cylindrical lens 13 from being displaced from the vibrating mirror unit 2 with respect to the environmental temperature change. Further, in the above embodiment, the convex portion of the cylindrical lens 13 is installed outside the housing 14, but instead, the convex portion of the cylindrical lens 13 can be installed inside the housing 14. By installing the convex portion inside, the cylindrical lens 13 is hardly damaged, and the optical scanning device 20 can be configured compactly.

  In the above embodiment, the oscillating mirror 2 is induced to oscillate by the piezoelectric body 7. Instead of this, an electrode is provided on the concave portion or the inner side surface of the fixed frame 6 below the oscillating mirror 2. It may be provided to induce oscillation by electrostatic force. Alternatively, a coiled electrode may be formed on the oscillating mirror unit 2 and a permanent magnet or an induction magnet may be installed below the oscillating mirror unit 2 to induce oscillation by a Lorentz force based on a magnetic field.

  FIG. 4 is a plan view illustrating a planar shape of the vibration mirror unit 2. In FIG. 4A, the shape of the oscillating mirror unit 2 is a hexagon. The width L2 of the long axis in the Y direction orthogonal to the rocking axis X direction is wider than the width L1 of the short axis in the rocking axis X direction. And the corner part of the long axis which is not irradiated with an incident light beam is cut. By cutting the corner portion, the moment of inertia can be reduced by reducing the mass of the vibrating mirror portion 2 without reducing the reflection efficiency. In FIG. 4B, the vibrating mirror unit 2 has an elliptical shape. The rocking axis X direction is the short axis, and the Y direction perpendicular thereto is the long axis. In this case as well, similarly to FIG. 4A, the mass and the moment of inertia can be reduced without reducing the reflection efficiency, so that a high resonance frequency can be obtained. In FIG. 4A, the oscillating mirror 2 is hexagonal, but it can be a polygon having a larger number of angles. Moreover, it is good also as a substantially polygon which chamfered the corner | angular of a polygon.

  FIG. 5 is a perspective view showing a disassembled state of the optical scanning device 25 according to the embodiment other than the present invention. The same reference numerals are assigned to the same parts or parts having the same function. The optical scanning device 25 includes an optical scanning unit 1, a storage unit 11 that stores the optical scanning unit 1, and a lid unit 10 that is installed on the storage unit 11. A transmissive portion 12 is formed on the lid portion 10. The transmission unit 12 has a first cylindrical lens 13a as a first optical element for converging the incident light beam, and a second light beam for converging the light beam reflected by the vibration mirror unit 2 and emitting it as a reflected light beam. And a second cylindrical lens 13b as an optical element. In the present embodiment, the lid portion 10, the transmission portion 12, and the two cylindrical lenses 13a and 13b are integrally formed of synthetic resin. Also in this case, the transmission part 12 and the lid part 10 can be separated and configured separately.

  FIG. 6 is an explanatory diagram showing a cross section and an optical path of the transmission part 12 that constitutes two cylindrical lenses 13a and 13b as optical elements. The same reference numerals are assigned to the same parts or parts having the same function. A first cylindrical lens 13 a and a second cylindrical lens 13 b are formed in the transmission part 12. In FIG. 6, the front and back directions of the paper orthogonal to the swing axis X direction have the same cross-sectional shape. Therefore, the cylindrical lenses 13a and 13b have a rotationally asymmetric shape with respect to the optical axis of each cylindrical lens. The incident light beam Iin passes through the first cylindrical lens 13a and converges on the reflecting surface formed on the surface of the oscillating mirror unit 2, and the reflected light passes through the second cylindrical lens 13b and is converged on the reflected light beam Iout. The In this case, the converged incident light beam Iin has a shape corresponding to the shape of the strip-like vibrating mirror portion 2. Therefore, the cylindrical lenses 13a and 13b have optical characteristics in which the power with respect to the axial direction of the swing shaft is larger than the power with respect to the direction perpendicular thereto.

  The vibration mirror unit 2 swings about the swing axis X, and the reflected light beam Iout is scanned in a direction orthogonal to the swing axis X. As described above, by separating the cylindrical lens 13 for the incident light beam and the reflected light beam, it is possible to control the characteristics of the reflected light beam, for example, the degree of convergence or divergence, as compared with the case where a single cylindrical lens is used. It becomes possible. Further, the degree of freedom in designing the angle between the incident light beam and the reflected light beam can be increased. Furthermore, there is an effect that the incident angle of the incident light beam and the reflection angle of the reflected light beam can be set freely.

  FIG. 7 is an explanatory diagram showing a cross section and an optical path of the transmissive portion 12 constituting the Fresnel lens 15 as an optical element. The same parts and parts having the same functions are denoted by the same reference numerals. In FIG. 7, the Fresnel lens 15 represents a cross section in the swing axis X direction, and has the same cross-sectional shape in the vertical direction of the paper orthogonal to the swing axis X direction. Accordingly, the Fresnel lens 15 has a rotationally asymmetric shape with respect to its optical axis. The incident light beam Iin is converged on the reflection surface formed on the surface of the vibration mirror unit 2 by the Fresnel lens 15, and the reflected light is converged through the Fresnel lens 15 and emitted as a reflected light beam Iout. The converged incident light beam Iin is converged to a shape along the shape of the reflection surface on the reflection surface of the vibrating mirror unit 2. Accordingly, the Fresnel lens 13 has optical characteristics in which the power with respect to the axial direction of the swing axis is greater than the power with respect to the direction perpendicular thereto.

  The emitted reflected light beam Iout is scanned in a direction orthogonal to the swing axis X direction by the swing of the vibration mirror unit 2. Since the Fresnel lens 15 can be formed thinner than a normal lens, the shape of the optical scanning device 20 can be made compact and the weight can be reduced. The Fresnel lens 15 may be formed separately for the incident light beam and the reflected light beam. Further, the Fresnel lens 15 can be formed on the inner side of the transmission part 12. If it is formed on the inner side, the lens is less likely to be scratched.

  FIG. 8 is an explanatory diagram showing a cross section and an optical path of the transmission part 12 that constitutes the diffraction grating 16 as an optical element. The same parts and parts having the same functions are denoted by the same reference numerals. In the diffraction grating, grooves 17 that diffract light at a specific interval are formed on the surface of the transmission part 12. The groove 17 has the same cross-sectional shape in the front and back direction of the paper surface orthogonal to the swing axis X. The incident light beam Iin is diffracted by the diffraction grating 16 and converges in a shape along the shape of the reflection surface formed on the surface of the vibration mirror unit 2. The reflected light is converged through the diffraction grating 16 and emitted as a reflected light beam Iout. The grooves 17 of the diffraction grating 16 can be formed on the inner side of the transmission part 12.

  FIG. 9 is an explanatory diagram showing the transmission section 12 and the optical path that constitute the gradient index lens 18 as an optical element. The same parts and parts having the same functions are denoted by the same reference numerals. The gradient index lens is composed of a member whose refractive index is distributed in the plane of the transmission part 12. The first optical element of the transmission part 12 is formed of a member whose refractive index decreases toward the periphery centering on the optical axis position P1 of the incident light beam Iin. Similarly, the second optical element of the transmissive portion 12 is formed of a member whose refractive index decreases toward the periphery with the optical axis position P2 of the reflected light beam Iout as the center. In FIG. 9, it has the same refractive index distribution in the vertical direction of the paper. As a result, the incident light beam Iin is converged in the direction of the swing axis X of the vibration mirror unit 2. The reflected light reflected by the vibration mirror unit 2 is converged and emitted as a reflected light beam Iout. Therefore, in the gradient index lens 18, the power in the direction of the swing axis X of the vibration mirror unit 2 is larger than the power in the direction orthogonal to the direction. The parallel plate type gradient index lens 18 has no convex portion. Therefore, the optical scanning device 20 can be configured to be compact and lightweight. When the angle difference between the incident light beam Iin and the reflected light beam Iout is small, the refractive index distribution of the gradient index lens 18 is decreased from the center position P3 of the transmission unit 12 toward the peripheral region. .

  As described above, the first optical element and the second optical element have been described using various lenses and the like. However, the fθ characteristic and the arc are compared with the second optical element that allows the reflected light beam reflected by the vibration mirror unit 2 to pass therethrough. Sign characteristics can be imparted. For example, when the oscillating mirror unit 2 oscillates at a constant angular velocity with respect to the oscillating axis, the fθ characteristic is imparted to the second optical element. By giving the fθ characteristic, the scanning speed is made substantially constant on the projection surface that is irradiated with the reflected light beam through the second optical element, such as a photosensitive drum such as a laser printer, a flat screen of an image display device, or the like. can do. As a result, it is possible to suppress or eliminate variations in image density between the central region and the peripheral region of the projected image.

  For example, when the oscillating mirror unit 2 swings due to resonance, an arc sine characteristic is imparted to the second optical element. By giving the arc sine characteristic, a curved surface such as a retina, a hemispherical screen, or a cylindrical screen of a user of a retinal scanning display device that a reflected light beam that has been scanned at a constant angular velocity through the second optical element reaches. In this case, the scanning speed can be made substantially equal. This is because, when the oscillating mirror unit 2 oscillates due to the resonance vibration, the oscillating mirror unit 2 oscillates with a sine characteristic as the time evolution of the oscillation angle thereof. Therefore, the angular velocity decreases as the swing angle of the oscillating mirror unit 2 increases, and the image density projected on the projection plane varies. By giving an arc sine characteristic to the second optical element, the scanning speed can be made substantially equal on the curved projection surface as described above where the reflected light beam is irradiated through the second optical element. Thereby, variation in pixel density on the curved projection surface can be suppressed or eliminated.

  FIG. 10 is a block diagram of a retinal scanning display device 30 using the optical scanning device 20 or 25. The same reference numerals are assigned to the same parts or parts having the same function.

  In FIG. 10, the retinal scanning display device 30 directly forms an image on the retina 50 of the eyeball 48 of the observer. Video light emitted from the B laser 37 that emits blue light, the G laser 38 that emits green light, and the R laser 39 that emits red light is converted into parallel light by the collimating optical system 40 and is synthesized by the dichroic mirror 41. The light is condensed by the coupling optical system 42 and introduced into the optical fiber 49. The image light emitted from the optical fiber 49 is applied to the vibration mirror unit 2 of the optical scanning device 20 or 25 described with reference to FIGS. The oscillating mirror unit 2 is driven and oscillated by a horizontal scanning drive circuit 44 to horizontally scan the reflected light. The horizontally scanned image light is applied to the galvanometer mirror 51 via the relay optical system 45. The galvanometer mirror 51 scans the reflected light in the vertical direction with its mirror surface oscillated by a magnetic field. The image light reflected from the galvanometer mirror 51 is imaged on the retina 50 of the eyeball 48 via the second relay optical system 53.

  The video signal supply circuit 33 inputs a video signal and outputs image signals corresponding to blue (B), green (G) and red (R) colors to a B laser driving circuit 34, a G laser driving circuit 35 and an R laser driving. Output to each of the circuits 36. The B laser 37 emits a B-color laser beam whose light intensity is modulated based on a drive signal from the B laser drive circuit 34. Similarly, the G laser 38 and the R laser 39 emit laser light of each color whose light intensity is modulated based on each image signal.

  The video signal supply circuit 33 outputs a synchronizing signal synchronized with the image signal to the horizontal scanning driving circuit 44 and the vertical scanning driving circuit 46. The horizontal synchronizing signal circuit 31 outputs a horizontal synchronizing signal to the horizontal scanning driving circuit, and the vertical synchronizing signal circuit 32 outputs a vertical synchronizing signal to the vertical scanning driving circuit 46. The horizontal scanning drive circuit 44 outputs a drive signal to the optical scanning device 20 to swing the oscillating mirror unit 2. The oscillation in this case is based on the resonant oscillation of the oscillating mirror unit 2. The photo sensor 55 receives a part of the light horizontally scanned by the horizontal scanning drive circuit 44, converts it into an electrical signal, and outputs it to the BD signal detection circuit 47. The BD signal detection circuit 47 detects the timing of horizontal scanning and outputs a timing signal to the video signal supply circuit 33. The video signal supply circuit 33 accurately determines the start timing of the video signal based on the input timing signal.

  In the retinal scanning display device 30, the galvano mirror 51 is used for the vertical scanning, but the optical scanning device 20 can be used for this. The vertical scanning frequency is as low as about 60 Hz, for example. Therefore, the mirror part is swung by the torsion angle control by the electric signal without using the resonance vibration.

  In FIG. 10, the example in which the optical scanning device 20 is applied to the retinal scanning display device 30 has been described. However, the second relay optical system 53 is changed to a projection lens system, and the eyeball 48 is changed to a projection screen or a building. If it is set as a wall etc., it can be set as a projection type optical scanning display apparatus. In the embodiment of FIG. 10, an RGB full-color display device is used. However, for example, a large-screen optical scanning display device can be obtained by scanning one or two colors of laser light.

  FIG. 11 is a schematic block diagram in which the optical scanning device 20 or 25 is used as the optical scanning device 25 used in the laser printer 60. The same reference numerals are assigned to the same parts or parts having the same function.

  In FIG. 11, a laser light source 61 to which a modulation signal for forming an image is input irradiates the optical scanning device 20 with a laser beam. The incident light beam incident on the first cylindrical lens 13a as the first optical element of the optical scanning device 20 is converged on the vibration mirror unit 2 in the housing 14 and scanned in a direction perpendicular to the swing axis X. . The scanned reflected light is converged by the third cylindrical lens 13c having the Fθ lens function as the second optical element and emitted as a reflected light beam. The reflected light beam is reflected by the concave mirror 62 and forms an image on the photosensitive member 63 on the rotating drum 64, thereby forming an electrostatic latent image on the photosensitive member 63. The rotating drum 64 rotates to transfer the electrostatic latent image onto a copy sheet (not shown). The optical scanning device 20 can use the optical traveling device described with reference to FIGS. In this case, it is necessary to provide the Fθ lens function to the emission part of the first optical element or the second optical element. The Fθ lens function is a function for correcting the beam speed so that the beam spot on the photoconductor 63 moves at a substantially constant speed.

  Although the embodiment of the optical scanning device 25 used in the laser printer has been described with reference to FIG. 11, the optical scanning device is also used in a one-dimensional or two-dimensional barcode reading device or the like. The optical scanning device 20 or 25 described with reference to 9 can be used.

  12 and 13 are explanatory views showing a method of manufacturing the optical scanning device 20 according to the embodiment of the present invention. FIG. 12 shows a process until the optical scanning unit 1 is formed, and FIG. 13 shows a process until the optical scanning unit 1 is housed in the housing 14 and the optical scanning device 25 is formed. The same parts and parts having the same functions are denoted by the same reference numerals.

  FIG. 12A is a top view showing a vibrating body sheet 70 in which nine frame portions 5 surrounding the vibrating mirror portion 2 and the like are formed. The vibrating body sheet 70 is made of a silicon semiconductor substrate, and inside the frame portion 5 is a vibrating mirror portion 2, a support portion 3 that points to the vibrating mirror portion 2, and a beam portion 4 that holds the supporting portion 3 and is fixed to the frame portion 5. Are integrally formed with the frame portion 5. The vibrating body sheet 70 can be manufactured as follows. A silicon semiconductor substrate is prepared, a photoresist is applied to the surface of the silicon semiconductor substrate, the photoresist is patterned by a photolithography process, and an etching mask is formed. Next, an unnecessary silicon semiconductor substrate is removed by dry etching or wet etching. Thereafter, the remaining etching mask is removed, and the piezoelectric body 7 (not shown) is bonded and fixed across the beam portion 4 and the frame portion 5. An electrode made of metal or the like is formed in advance in the region where the piezoelectric body on the surface of the silicon semiconductor substrate is bonded and fixed. Further, although a silicon semiconductor substrate is used in this embodiment mode, a metal material, a glass material, or the like can be used instead of the silicon semiconductor substrate.

  FIG. 12B is a top view of a fixed frame sheet 71 in which nine fixed frame portions 6 are formed for fixing the frame portion 5 to form the swing space 9. The fixed frame sheet 71 is made of heat resistant glass. The fixed frame sheet 71 can be manufactured as follows. First, a heat resistant glass plate is prepared. Next, a photoresist is applied on the heat-resistant glass plate, and the photoresist is patterned by a photolithography process to form an etching mask. Next, wet etching or dry etching is performed to etch the heat resistant glass to a depth necessary to form the oscillating space 9. Thereafter, the remaining etching mask is removed. Further, the fixed frame sheet 71 can be heated to the softening temperature of the heat-resistant glass to form the recesses with a pressing die.

  FIG. 12C is a perspective view for explaining a process of arranging and fixing the vibrator sheet 70 on the fixed frame sheet 71. The vibrating body sheet 70 is fixed to the fixed frame sheet 71 by anodic bonding. Next, the center of the convex portion of the fixed frame portion 6 of the vibrating body sheet 70 is cut and separated by a cutter to manufacture the optical scanning portion 1. In addition, it can replace with anodic bonding and can also adhere and fix using an adhesive agent.

  FIG. 13E is a perspective view of a storage portion sheet 72 in which nine storage portions 11 are formed in a sheet shape. The storage section sheet 72 is made of ceramic made of alumina. An alumina green sheet is formed, and a concave portion 19 for accommodating the optical scanning unit 1 is formed on the green sheet by a pressing die or the like, and the green sheet is sintered. In addition to the ceramics such as alumina, the storage sheet 72 can use an organic material such as synthetic resin or an inorganic material such as glass.

  FIG. 13F is a perspective view of a lid portion sheet 73 in which nine lid portions 10 are formed in a sheet shape. Each lid 10 is integrally formed with a first cylindrical lens 13a as a first optical element and a second cylindrical lens 13b as a second optical element. The lid 10 uses a translucent synthetic resin material. The cylindrical lenses 13a and 13b were formed by precision press molding using a mold.

  FIG. 13G is a perspective view illustrating a state in which the optical scanning unit 1 is stored in the storage unit 11 of the storage unit sheet 72. The optical scanning unit 1 is stored in the storage unit 11 with the bottom fixed. Next, wiring for supplying power to the piezoelectric body 7 is installed by wire bonding or the like, and connected to a terminal (not shown) provided on the bottom of the storage unit 11 or the side wall of the storage unit 11. FIG. 13H is a perspective view illustrating a state where the optical scanning unit 1 is stored in all the storage units 11 and the lid sheet 73 is placed. The lid portion sheet 73 is placed on and adhered to the storage portion sheet 72. Next, as shown in FIG. 13D, the optical scanning device 25 is separated and completed.

  In the above description, the multiple optical picking of the nine optical scanning devices has been described, but it goes without saying that a larger number of multiple optical picking can be performed. Further, in the method of manufacturing the optical scanning device in the above embodiment, the vibrating body sheet 70 and the fixed frame sheet 71 are formed separately and bonded and fixed by anodic bonding as shown in FIG. However, it can be integrally formed on the silicon semiconductor substrate from the beginning without being separated into the vibrating body sheet 70 and the fixed frame sheet 71. That is, the vibrating mirror part 2, the support part 3, the beam part 4, and the frame part 5 are formed in a convex shape by a photolithography process and an etching process, and then the vibrating mirror part 2, the support part 3, and the beam part are anisotropically etched. The silicon semiconductor in the lower region of 4 is removed. That is, the oscillating space is formed on the silicon semiconductor substrate. Thereafter, the center of the frame portion 5 is cut by dicing and separated into individual optical scanning portions 1. In this way, it is possible to further reduce manufacturing steps and reduce costs.

It is a perspective view of the optical scanning part of the optical scanning device concerning the embodiment of the present invention. It is a perspective view of the housing | casing which accommodates the optical scanning part of the optical scanning device which concerns on embodiment of this invention. It is explanatory drawing showing the incident light beam and outgoing light beam of the optical scanning device which concerns on embodiment of this invention. It is a top view of the vibration mirror part of the optical scanning device concerning the embodiment of the present invention. It is a perspective view of the housing | casing which accommodates the optical scanning part of the optical scanning device which concerns on other embodiment of this invention. It is explanatory drawing showing the window part cross section and light beam of the optical scanner which concerns on embodiment of this invention. It is explanatory drawing showing the window part cross section and light beam of the optical scanner which concerns on embodiment of this invention. It is explanatory drawing showing the window part cross section and light beam of the optical scanner which concerns on embodiment of this invention. It is explanatory drawing showing the window part cross section and light beam of the optical scanner which concerns on embodiment of this invention. 1 is a block diagram illustrating a retinal scanning image display apparatus according to an embodiment of the present invention. 1 is a schematic block diagram of a laser printer according to an embodiment of the present invention. It is explanatory drawing showing the manufacturing method of the optical scanning device which concerns on embodiment of this invention. It is explanatory drawing showing the manufacturing method of the optical scanning device which concerns on embodiment of this invention. It is a typical sectional view showing a conventionally well-known optical deflector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical scanning part 2 Vibration mirror part 3 Support part 4 Beam part 5 Frame part 7a, 7b, 7c, 7d Piezoelectric body 8a, 8b, 8c, 8d Electrode 9 Swing space 10 Lid part 11 Storage part 12 Transmission part 13 Cylindrical lens 14 Case

Claims (12)

An optical scanning unit having a vibration mirror unit having a reflecting surface, a support unit that forms a swing axis of the vibration mirror unit, and a frame unit for holding the support unit, and the optical scanning unit are housed. An optical scanning device that emits a reflected light beam that is scanned by reflecting an incident light beam by the oscillating mirror part that swings.
The vibrating mirror portion has a shape in which an axial width of the swing shaft is narrower than a width in a direction perpendicular to the swing shaft,
The housing includes a transmission part that transmits the incident light flux and the reflected light flux,
The transmission unit includes a first optical element that converges the incident light beam into a cross-sectional shape corresponding to a shape of the vibrating mirror unit, and a cross-sectional shape corresponding to the light beam before the reflected light beam is incident on the first optical element. A second optical element that converges to return to
The first optical element and the second optical element have at least power with respect to the axial direction of the swing axis, and the power with respect to the axial direction is larger than the power with respect to the direction orthogonal to the swing axis. An optical scanning device having characteristics . The vibrating mirror unit according to claim 1, wherein the axial direction of the pivot axis and minor axis, and having a substantially polygonal or elliptical in shape and the direction perpendicular to the axial direction and the long axis Optical scanning device. It said first optical element includes an optical scanning device according to claim 1 or claim 2 characterized in that it has a rotationally asymmetric shape with respect to the optical axis of the first optical element. It said first optical element includes an optical scanning apparatus according to any one of claims 1 to 3, characterized in that a cylindrical lens. It said first optical element includes an optical scanning apparatus according to any one of claims 1 to 3, characterized in that a Fresnel lens. It said first optical element includes an optical scanning apparatus according to any one of claims 1 to 3, characterized in that a diffraction grating. It said first optical element includes an optical scanning apparatus according to any one of claims 1 to 3, characterized in that a gradient index lens. The optical scanning device according to claim 1, wherein the second optical element has an fθ characteristic with respect to a direction orthogonal to the swing axis . The optical scanning device according to claim 1, wherein the second optical element has an arc sine characteristic with respect to a direction orthogonal to the swing axis . The housing includes a storage unit that stores the optical scanning unit and a cover unit that covers the storage unit, and the cover unit is made of the same material as the transmission unit and the first optical element. the optical scanning device according to any one of claims 1 to 9, characterized in that it is formed. The optical scanning device according to claim 10 , wherein the storage portion and the lid portion have substantially the same linear expansion coefficient. Includes the optical scanning apparatus according to any one of claims 1 to 11 retinal scanning display apparatus which projects and displays on the retina the light beam modulated by and scanned by the optical scanning device according to an image signal.

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