JP4715595B2 - Optical scanner and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an optical scanner that scans reflected light from a reflecting surface by the oscillation of the reflecting surface on which incident light is incident, and an image forming apparatus including the same, and more particularly, to the reflecting surface of the optical scanner. It relates to structural improvements.

  There is already known an optical scanner that scans the reflected light from the reflecting surface by swinging the reflecting surface on which incident light is incident (see, for example, Patent Document 1). Such an optical scanner is used, for example, in the field of image formation or the field of image reading. In the field of image formation, it is used for applications such as a retinal scanning display device, a projector, a laser printer, and laser lithography that scans a light beam on the retina to directly display an image. Used in applications such as copying machines, image scanners, and barcode readers.

  In this type of optical scanner, there is a case where it is strongly demanded to be small and light, and to suppress a decrease in the amount of light after reflection as much as possible. An optical scanner is described as a conventional example.

In this conventional example, an oscillating body having a reflecting surface is oscillated around an oscillating axis by supplying electric charges to a piezoelectric body mounted on the oscillating body, and thereby incident obliquely on the reflecting surface. It is configured to scan light.
JP 2005-181455 A

  However, the conventional examples described above have the following problems.

  That is, in the image forming apparatus shown in Patent Document 1, light is incident on the reflecting surface of the optical scanner obliquely, and the area of the incident region formed on the reflecting surface by the incident is the light incident on the reflecting surface. Therefore, the area of the reflecting surface must be increased. For this reason, there is a problem that the size of the optical scanner is increased.

  Moreover, the reflection surface of the optical scanner is a mirror surface, and the reflected light is emitted at the same angle as the angle at which the light is incident on the reflection surface, and the traveling direction of the reflected light is determined. For this reason, there is a problem that the arrangement of the optical scanner is limited. Therefore, it is often necessary to increase the mounting space of the entire optical system including the optical scanner.

  Accordingly, the present invention provides an optical scanner capable of reducing the area of the reflecting surface of the optical scanner as much as possible and reducing the mounting space as much as possible, and an image forming apparatus including the optical scanner. The purpose is to provide.

The optical scanner according to claim 1, wherein in the optical scanner that scans the reflected light from the reflecting surface by swinging of the reflecting surface that reflects incident incident light, a diffraction structure is formed on the reflecting surface, and the diffraction The structure has a first diffractive structure that emits at least a first light beam having a predetermined wavelength of the incident light in a direction of a predetermined diffraction angle by diffraction, and has a geometric shape different from that of the first diffractive structure. And a second diffractive structure that emits a second light beam having a wavelength different from that of the first light beam in the incident light in the direction of the predetermined diffraction angle .

  According to a second aspect of the present invention, in the configuration of the optical scanner according to the first aspect, the diffractive structure is a structure in which the intensity of the diffracted light of a specific order is stronger than the intensity of diffracted light other than the specific order. .

  An optical scanner according to a third aspect of the present invention is the configuration of the optical scanner according to the first or second aspect, further comprising an oscillating body that oscillates together with the reflecting surface for the scanning, wherein the diffractive structure is Consists of the same material as the oscillator.

  According to a fourth aspect of the present invention, in the configuration of the optical scanner according to the third aspect, the diffractive structure is formed by wet etching or dry etching.

  An optical scanner according to a fifth aspect of the present invention is the configuration of the optical scanner according to the first or second aspect, further comprising an oscillating body that oscillates with the reflecting surface for the scanning, wherein the diffractive structure is the diffractive structure. It is made of a material different from that of the oscillator.

  The optical scanner according to claim 6 is the configuration of the optical scanner according to claim 5, wherein the diffractive structure is formed of a resin film formed on the oscillating body, and a mold having a fine concavo-convex pattern is formed. It is formed by a nanoimprint method in which the concave / convex pattern of the mold is transferred to the resin film by being pressed against the resin film.

  The optical scanner according to claim 7 is the configuration of the optical scanner according to any one of claims 1 to 6, wherein the diffraction structure is a one-dimensional diffraction grating structure.

  The optical scanner according to claim 8 is the configuration of the optical scanner according to any one of claims 1 to 6, wherein the diffraction structure is a two-dimensional diffraction grating structure.

  The optical scanner according to claim 9 is the configuration of the optical scanner according to any one of claims 1 to 6, wherein the diffractive structure is a hologram structure in which the incident light is condensed or diffused. .

The optical scanner according to claim 10 is the configuration of the optical scanner according to claim 8 or claim 9, wherein the diffractive structure converts the incident light into a plurality of diffracted lights of a specific order and diffracted lights of other orders. In this structure, the light is divided into reflected light.

The image forming apparatus according to claim 11 is an image forming apparatus that forms an image by scanning a light beam, wherein the light source emits the light beam, and the light according to any one of claims 1 to 9. A scanner that scans the light beam emitted from the light source by the optical scanner.

An image forming apparatus according to a twelfth aspect of the present invention is an image forming apparatus that forms an image by scanning a light beam, the light source that emits the light beam, and the optical scanner according to claim 10, A light beam emitted from the light source by scanning is divided into at least two light beams, and at least one light beam among the divided light beams is scanned in a predetermined scanning direction, and within the range of the scanning by the optical scanner And a light detector for detecting passage of light beams other than a predetermined scanning direction among the divided light beams, and controlling timing of emitting the light beams from the light source based on detection signals from the light detectors Control means.

An image forming apparatus according to a thirteenth aspect is an image forming apparatus that forms an image by scanning a light beam according to an image signal, the light source that emits the light beam, and any one of claims 1 to 9. has an optical scanner according to claim, by the optical scanner, a scanning unit for scanning the light beam emitted from the light source, among the light beam scanned by the scanning unit, and transmits at least the first light beam, Shielding means for shielding a light beam other than the first light beam adjacent to the first light beam.

The image forming apparatus according to claim 14 is the image forming apparatus according to any one of claims 11 to 13 , wherein the optical scanner makes the light beam incident in a direction perpendicular to the reflecting surface. , And arranged at a position where the light is emitted in an oblique direction with respect to the reflection surface.

The image forming apparatus according to claim 15 is the image forming apparatus according to any one of claims 11 to 13 , wherein the optical scanner makes the light beam incident obliquely with respect to the reflection surface. , And arranged at a position where the light exits in a direction perpendicular to the reflecting surface.

The image forming apparatus according to claim 16 is the image forming apparatus according to any one of claims 11 to 13 , wherein the optical scanner enters the light beam in an oblique direction with respect to the reflection surface. , And is disposed at a position where the light exits in a direction having a reflection angle different from the incident angle with respect to the reflection surface.

In addition to the image forming apparatus according to any one of claims 11 to 16 , the image forming apparatus according to claim 17 causes a light beam emitted from the light source to be incident on the reflection surface of the optical scanner. On the other hand, it has an optical system that emits light at different incident angles for each wavelength band of the luminous flux.

In addition to the image forming apparatus according to any one of claims 11 to 16 , the image forming apparatus according to claim 18 is an optical that corrects chromatic aberration generated based on a wavelength difference of a light beam emitted from the light source. Has a system.

An image forming apparatus according to a nineteenth aspect is the image forming apparatus according to the eighteenth aspect , wherein the optical system for correcting the chromatic aberration is constituted by a diffractive optical element.

According to a twentieth aspect of the present invention , in the image forming apparatus according to the nineteenth aspect , the diffractive optical element is provided on a reflection surface of a second optical scanner provided at a subsequent stage of the optical scanner.

The image forming apparatus according to claim 21 is the image forming apparatus according to any one of claims 11 to 20 , wherein an image is guided by guiding a light beam scanned by the optical scanner onto a retina of an eye. This is a retinal scanning image display device that performs projection display.

  According to the optical scanner of the first aspect, since the diffractive structure is formed on the reflection surface, the reflection direction of the reflected light can be changed to a desired direction, and the degree of design freedom can be increased. For example, even if incident light is incident in a direction perpendicular to the reflecting surface, the reflected light can be emitted in an oblique direction with respect to the reflecting surface. The entire optical system can be reduced in size.

In addition, as described above, when incident light is incident in a direction perpendicular to the reflecting surface, the incident area formed on the reflecting surface is enlarged by reflecting the transverse section with respect to the traveling direction of the incident light as it is. In other words, the area of the reflection surface of the optical scanner can be made as small as possible compared to the case where incident light is incident obliquely with respect to the reflection surface. Furthermore, since the diffractive structure has at least a first diffractive structure for the first light beam and a second diffractive structure for the second light beam, red, blue, and green having different wavelengths are the same as incident light. Even when the light is incident on the reflecting surface of the optical scanner at an incident angle, only the image light necessary for image formation can be sent in the same direction, and the problem of chromatic aberration due to the difference in wavelength can be solved.

  According to the optical scanner of the second aspect, since the diffractive structure has a shape in which the diffracted light intensity of the specific order is stronger than the diffracted light intensity of the other orders, the incident light incident on the reflecting surface Among them, the desired order of diffracted light intensity required for image formation can be improved, and good diffraction efficiency (specific order diffracted light intensity ratio with respect to incident light intensity) can be obtained.

  According to the optical scanner of the third aspect, since the diffractive structure is made of the same material as the oscillating body, the oscillating body oscillates together with the reflecting surface for scanning. The surface can be integrally formed, and the device can be formed at low cost.

  According to the optical scanner of claim 4, since the diffractive structure is formed by wet etching or dry etching, it is possible to process a fine uneven pattern on the reflecting surface and to process a base material with high hardness. Therefore, a soft material such as silicon can be easily processed.

  According to the optical scanners of the fifth and sixth aspects, the oscillating body that oscillates with the reflecting surface for scanning is provided, and the diffractive structure is formed of a material different from that of the oscillating body. By forming a resin film on the moving body and pressing the mold with a fine concavo-convex pattern against the resin film, it is formed by a nanoimprint method that transfers the concavo-convex pattern of the mold to the resin film. Can be realized simply and at low cost, and a nanoscale structure can be formed very easily.

  According to the optical scanner of the seventh aspect, since the diffraction structure is a one-dimensional diffraction grating structure, the reflection direction of the reflected light emitted from the reflection surface can be changed one-dimensionally in an arbitrary direction.

  According to the optical scanner of the eighth aspect, since the diffraction structure is a two-dimensional diffraction grating structure, the reflection direction of the reflected light emitted from the reflection surface can be changed two-dimensionally in an arbitrary direction.

  According to the optical scanner of claim 9, since the diffractive structure is a hologram structure in which incident light is condensed or diffused light, when the image is enlarged in a wide range, the light is diffused and reduced in a narrow range. Increases the degree of freedom in image formation.

  According to the optical scanner of claim 10, since the diffractive structure is a structure that divides incident light into a plurality of reflected lights, at least one of the plurality of reflected lights is used as image light for image formation, and the others. The divided reflected light can be used for various purposes, such as for controlling the timing of image display and for detecting the scanning time.

According to the image forming apparatus of the eleventh aspect, since the optical scanner according to any one of the first aspect to the ninth aspect is provided, the optimum diffractive structure to be formed on the reflecting surface is selected, so that the incident light is incident. The reflection direction in which the light is reflected by the reflecting surface can be freely set. Therefore, the degree of freedom in designing the entire image forming apparatus is increased, and the entire optical system can be designed as thin as possible.

According to an image forming apparatus of a twelfth aspect , the optical scanner according to the tenth aspect includes the optical scanner according to the tenth aspect, and the light beam emitted from the light source by the scanning of the optical scanner is divided into at least two light beams. A scanning unit that scans at least one light beam in a predetermined scanning direction, and a light beam other than the predetermined scanning direction among the divided light beams, which is disposed within the scanning range by the optical scanner. Since it has a photodetector for detecting the passage and a control means for controlling the timing of emitting the light beam from the light source based on a detection signal from the photodetector, it is incident on the reflecting surface of the optical scanner for the photodetector. There is no need to enter light separately.

According to the image forming apparatus of the thirteenth aspect , light beams other than the first light beam that transmits at least the first light beam and is adjacent to the first light beam among the light beams scanned by the scanning unit by the shielding unit. In each diffractive structure divided into a plurality on the reflecting surface, only the image light necessary for image formation is sent to the next optical system, and in a different direction from the image light due to the difference in reflection angle based on the wavelength difference. It is not necessary to send other light to the next optical system, and image formation with higher image quality is possible.

According to the image forming apparatus of the fourteenth aspect , the fifteenth aspect, and the sixteenth aspect, since the incident direction and the reflection direction of the incident light on the reflection surface of the optical scanner can be freely set, the design freedom of the image forming apparatus is improved. The degree of expansion increases and the entire apparatus can be downsized.

According to the image forming apparatus of the seventeenth aspect, since the optical system emits the light beam emitted from the light source at different incident angles for each wavelength of the light beam with respect to the reflection surface of the optical scanner, The incident angle can be adjusted so that the reflection angle is the same for all light fluxes, and the chromatic aberration of the reflection surface of the optical scanner can be corrected to form an image with higher image quality.

According to the image forming apparatus of claim 18 , claim 19, and claim 20 , since the optical system corrects chromatic aberration caused by reflection of the light beam in the optical scanner based on the wavelength difference of the light beam emitted from the light source, It is possible to avoid the problem that the image becomes dark or expensive when measures such as coating the reflecting surface of the optical scanner with a material having a different refractive index to reduce the influence of chromatic aberration are taken.

According to the image forming apparatus of claim 21 , since the image forming apparatus is a retinal scanning image display apparatus that projects and displays an image by guiding the light beam scanned by the optical scanner onto the retina of the eye, the entire apparatus including the optical scanner Can be made as thin as possible.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 systematically shows a retinal scanning display device as an image forming apparatus according to an embodiment of the present invention. This retinal scanning display device (hereinafter abbreviated as “RSD”) adjusts the wavefront and intensity of a laser beam as a luminous flux as appropriate through the pupil 12 of the observer's eye 10 and the retina 14. Incident on the image plane. According to this RSD, a laser beam is scanned two-dimensionally on the image plane, and an image is directly projected onto the retina 14.

  This RSD includes a light source unit 20 as a light source, and further includes a scanning device 24 between the light source unit 20 and the eye 10 of the observer.

  The light source unit 20 includes an R laser 30 that emits red laser light and a green laser in order to combine three laser lights having three primary colors (RGB) into one laser light to generate laser light of an arbitrary color. A G laser 32 that emits light and a B laser 34 that emits blue laser light are provided. Each of the lasers 30, 32, and 34 can be configured as a semiconductor laser, for example.

  The laser beams emitted from the lasers 30, 32, and 34 are collimated by the collimating optical systems 40, 42, and 44 and then incident on the dichroic mirrors 50, 52, and 54 having wavelength dependency. Thereafter, the laser beams are selectively reflected and transmitted with respect to the wavelength by the dichroic mirrors 50, 52, and 54.

  Specifically, red laser light emitted from the R laser 30 is collimated by the collimating optical system 40 and then incident on the dichroic mirror 50. The green laser light emitted from the G laser 32 is incident on the dichroic mirror 52 through the collimating optical system 42. The blue laser light emitted from the B laser 34 is incident on the dichroic mirror 54 via the collimating optical system 44.

  The laser beams of the three primary colors incident on the three dichroic mirrors 50, 52, and 54 are finally incident on and combined with one dichroic mirror 54 that represents the three dichroic mirrors 50, 52, and 54. The light is collected by the coupling optical system 56.

  Although the optical part of the light source unit 20 has been described above, the electrical part will be described below.

  The light source unit 20 includes a signal processing circuit 60 mainly composed of a computer. The signal processing circuit 60 is designed to perform signal processing for driving the lasers 30, 32, and 34 and signal processing for scanning the laser beam based on a video signal supplied from the outside. Yes.

  In order to drive the lasers 30, 32, and 34, the signal processing circuit 60 determines the color necessary for the laser beam for each pixel on the image to be projected on the retina 14 based on the video signal supplied from the outside. A drive signal necessary for realizing the intensity is supplied to each laser 30, 32, 34 via each laser driver 70, 72, 74. Signal processing for scanning with a laser beam will be described later.

  The light source unit 20 includes a temperature control unit 602 having a temperature sensor 601 as a temperature detector. The temperature control unit 602 measures the temperature of the light source unit 20 and controls the temperature of the light source unit 20 to be kept constant based on the measured value. Since the temperature of the light source unit 20 is kept constant, the wavelength of the laser beam can be suppressed from fluctuating under the influence of the temperature change of the light source unit 20, so that the image projected on the retina 14 The formation of can be further stabilized. Note that the temperature control unit 602 controls the voltage applied to a Peltier element (not shown) provided around the light source unit 20 in order to keep the temperature of the light source unit 20 constant.

  The light source unit 20 described above emits a laser beam in the coupling optical system 56. The laser beam emitted therefrom passes through an optical fiber 82 as an optical transmission medium and a collimating optical system 84 for collimating the laser beam emitted from the rear end of the optical fiber 82 to the scanning device 24 in that order. Incident.

  The scanning device 24 includes a horizontal scanning system 100 and a vertical scanning system 102.

  The horizontal scanning system 100 is an optical system that performs horizontal scanning in which a laser beam is raster-scanned horizontally along a plurality of horizontal scanning lines for each frame of an image to be displayed. On the other hand, the vertical scanning system 102 is an optical system that performs vertical scanning in which a laser beam is scanned vertically from the first scanning line toward the last scanning line for each frame of an image to be displayed. The horizontal scanning system 100 is designed to scan the laser beam at a higher speed, that is, at a higher frequency than the vertical scanning system 102.

  In the present embodiment, the horizontal scanning system 100 includes an optical scanner 104 that performs horizontal scanning by swinging the reflecting surface by the vibration of an elastic body having a reflecting surface that performs mechanical deflection. The optical scanner 104 is controlled based on the horizontal synchronization signal supplied from the signal processing circuit 60. The configuration and operation of the optical scanner 104 will be described later.

  The laser beam horizontally scanned by the optical scanner 104 is transmitted to the vertical scanning system 102 by the relay optical system 194 as shown in FIG.

  As shown in FIG. 1, the RSD includes a beam detector 200 as a photodetector at a fixed position. The beam detector 200 is provided to detect the position of the laser beam in the main scanning direction by detecting the laser beam deflected by the optical scanner 104. An example of the beam detector 200 is a photodiode. The position detection of the laser beam in the main scanning direction by the beam detector 200 will be described later.

  As shown in FIG. 1, the vertical scanning system 102 includes a galvanometer mirror 210 as a swinging mirror that performs mechanical deflection. The laser beam emitted from the horizontal scanning system 100 is collected by the relay optical system 194 and enters the galvanometer mirror 210. The galvanometer mirror 210 is swung around a rotation axis that intersects the optical axis of the laser beam incident on the galvanometer mirror 210 by the vertical scanning drive circuit 211. The start timing and rotation speed of the galvanometer mirror 210 are controlled based on the vertical synchronization signal supplied from the signal processing circuit 60.

  In cooperation with the horizontal scanning system 100 and the vertical scanning system 102 described above, the laser beam is scanned two-dimensionally, and an image represented by the scanned laser beam passes through the relay optical system 214 to the eyes of the observer. 10 is irradiated. In the present embodiment, the relay optical system 214 includes a plurality of optical elements 215 and 218 arranged side by side on the optical path.

  The overall configuration and operation of the retinal scanning display device as the image forming apparatus according to the embodiment of the present invention have been described above. Next, the configuration and operation of the optical scanner 104 will be described in detail.

  FIG. 2 is a perspective view of the optical scanner 104 in an assembled state. On the other hand, FIG. 3 shows the optical scanner 104 in an exploded perspective view. As shown in FIGS. 2 and 3, the optical scanner 104 is configured by mounting a main body 110 on a base 112.

  The main body 110 is formed using an elastic material such as silicon. The thickness of the main body 110 is about 100 μm. As shown in the upper part of FIG. 3, the main body 110 generally has a thin plate rectangular shape having a through hole 114 through which light can pass. The main body 110 includes a fixed frame 116 on the outer side, and an oscillating body 124 having a reflection mirror unit 122 having a reflection surface 120 formed on the inner side. The reflection surface 120 is formed by a diffractive structure 401 that is a feature of the present invention, as will be described later.

  Corresponding to the configuration of the main body 110, the base 112 includes a support portion 130 to which the fixed frame 116 is to be attached and a rocking body 124 in the attached state with the main body 110 as shown in the lower part of FIG. 3. And a concave portion 132 that faces each other. The recess 132 is formed so as to have a shape that does not interfere with the base 112 even when the swinging body 124 is displaced by vibration in a state where the main body 110 is mounted on the base 112.

  As shown in FIG. 3, the reflecting surface 120 of the reflecting mirror section 122 is swung around a swing axis 134 that is also a symmetrical centerline thereof. The oscillating body 124 further includes a beam portion 140 that extends from the reflection mirror portion 122 on the same plane as that, and joins the reflection mirror portion 122 to the fixed frame 116. In the present embodiment, a pair of beam portions 140 and 140 extend in opposite directions from both sides of the reflection mirror portion 122.

  Each beam portion 140 includes one mirror side leaf spring portion 142, a pair of frame side leaf spring portions 144, 144, and a connecting portion that connects the mirror side leaf spring portion 142 and the pair of frame side leaf spring portions 144, 144 to each other. 146.

  In each beam portion 140, the mirror side leaf spring portion 142 extends from one of a pair of edges facing each other on the swing axis 134 of the reflection mirror portion 122 to the corresponding connection portion 146. The connecting portion 146 extends in a direction perpendicular to the swing axis 134. Further, in each beam portion 140, the pair of frame side leaf spring portions 144 and 144 are offset from the ends of the corresponding connection portions 146 in the opposite directions with respect to the swing axis 134, and the swing axis 134. Extending to the fixed frame 116.

  In each beam portion 140, as shown in FIG. 3, piezoelectric bodies 150, 152, 154, and 156 are attached to the pair of frame-side leaf spring portions 144 and 144 in a posture that reaches the fixed frame 116, respectively. Each of the piezoelectric bodies 150, 152, 154, and 156 is mainly composed of a piezoelectric element 160 as shown in FIG.

  The piezoelectric element 160 has a thin plate shape and is attached to one surface of the oscillator 124. The piezoelectric element 160 is sandwiched between the upper electrode 162 and the lower electrode 164 in a direction perpendicular to the sticking surface thereof, thereby constituting each piezoelectric body 150, 152, 154, 156. As shown in FIGS. 3 and 4, the upper electrode 162 and the lower electrode 164 are respectively connected to a pair of input terminals 168 and 168 installed on the fixed frame 116 by respective lead wires 166.

  As shown in FIG. 3, in this embodiment, four piezoelectric bodies 150, 152, 154, and 156 are provided at two pairs at opposite positions with the reflecting mirror portion 122 interposed therebetween, and with respect to the swing axis 134. They are arranged symmetrically with each other. Among these four piezoelectric bodies 150, 152, 154, 156, two piezoelectric bodies 150, 154 (located on the right side in FIG. 3) arranged at one facing position form a first pair, Two piezoelectric bodies 152 and 156 (located on the left side in FIG. 3) arranged at the other facing position form a second pair.

  In the present embodiment, the two piezoelectric bodies 150 and 154 forming the first pair function as drive sources, respectively, and swing the oscillator 124 by torsionally oscillating around the oscillation axis 134. Therefore, in each piezoelectric body 150, 154, a voltage is applied to the upper electrode 162 and the lower electrode 164, and thereby a displacement in the direction orthogonal to the application direction, that is, the length direction is generated in each piezoelectric body 150, 154. Be made.

  Due to this displacement, as shown in FIG. 5, the beam portion 140 is bent, that is, warped. This bending is performed with the connection portion with the fixed frame 116 of the beam portion 140 as a fixed end and the connection portion with the reflection mirror portion 122 as a free end. As a result, the free end is displaced upward or downward depending on whether the bending direction is upward or downward.

  The two piezoelectric bodies 150 and 154 forming the first pair are bent so that the free ends of the respective piezoelectric elements 160 are displaced in directions opposite to each other. As a result, the reflection mirror unit 122 is rotated around the swing axis 134 as shown in FIG.

  In short, each frame side leaf spring portion 144 has a function of converting the linear displacement of the piezoelectric element 160 attached thereto into a bending motion, and the connection portion 146 converts the bending motion of each frame side leaf spring portion 144 into the mirror side plate. It has a function of converting into the rotational motion of the spring part 142. The mirror side leaf spring portion 142 has a function of converting into a rotational motion. The reflection mirror 122 is rotated by the rotational movement of the mirror side leaf spring 142.

  In the present embodiment, by reciprocally displacing the two piezoelectric bodies 150 and 154 forming the first pair, the reciprocating rotational motion, that is, the rocking motion around the rocking axis 134 is caused to the reflection mirror portion 122. Be generated. In order to realize this, alternating voltages are applied to the two piezoelectric members 150 and 154 forming the first pair in opposite phases. As a result, when one of the two piezoelectric bodies 150 and 154 forming the first pair bends downward in FIG. 3, the other bends upward in FIG.

  Next, the configuration of the reflective diffraction structure 401 formed on the reflective surface 120 of the optical scanner 104 will be described in detail.

  FIG. 6 is an enlarged view of the diffractive structure 401 formed on the reflecting surface 120 of the optical scanner 104. This diffractive structure 401 has a plurality of grooves 499 having a sawtooth cross section formed on a reflection surface in a lattice shape so as to be parallel to each other, and is called a blazed type, which is a kind of one-dimensional diffraction grating. .

  The diffractive structure 401 reflects the laser beam incident from the light source unit 20 at a desired angle by using a diffraction phenomenon in which interference occurs between the light reflected by the smooth surface between the plurality of grooves 499. To do.

  The diffractive structure 401 is formed by a nanoimprint method. That is, a resin film is formed on a substrate made of silicon or the like on which the shape of the oscillating body 124 is formed, and a mold having a fine uneven pattern is pressed against the resin film, whereby the uneven pattern of the mold is changed to the resin. It is transferred to the film.

  Here, the diffraction phenomenon in the diffraction structure 401 will be briefly described with reference to FIG. As shown in FIG. 8, when incident light is incident on the diffractive structure 401 at an incident angle α, reflected light having a wavelength λ is diffracted at a diffraction angle β. Here, the incident light refers to a laser beam incident on the reflection surface of the optical scanner. Further, diffracted light refers to reflected light diffracted by a diffractive structure formed on the reflecting surface of the optical scanner. At this time, the following equation holds.

ここで、ｄ：格子溝間隔
α：入射角（入射光と回折構造法線とのなす角）
β：回折角（回折光と回折構造法線とのなす角）
ｍ：回折次数（ｍ≧０の整数）
λ：波長すなわち、光路差が波長の整数ｍ倍となる場合に、回折角βの方向の光が強め合うこととなる。

Where d: grating groove spacing α: incident angle (angle formed between incident light and diffraction structure normal)
β: Diffraction angle (angle between diffracted light and diffraction structure normal)
m: diffraction order (m ≧ 0 integer)
λ: Wavelength, that is, when the optical path difference is an integer m times the wavelength, the light in the direction of the diffraction angle β is intensified.

  Therefore, the diffractive structure 401 formed on the reflection surface 120 of the optical scanner 104 can be configured to emit a laser beam incident on the reflection surface 120 in the direction of a desired reflection angle β.

  In the present embodiment, as shown in FIG. 9, the optical scanner 104 has a diffraction in which a laser beam is incident on the reflecting surface 120 in a direction perpendicular to the reflecting surface 120 and is emitted in the direction of a desired reflection angle β with respect to the reflecting surface 120. A structure 401 is formed on the reflective surface 120.

  According to such a configuration, when a laser beam having a circular shape with a cross section 453 having a diameter a with respect to the traveling direction is incident on the reflecting surface 120 of the optical scanner 104, the incident region 454 of the laser beam has a cross section 453. And a circular shape with a diameter a which is the same shape as the above.

  On the other hand, as shown in FIG. 10, in the conventional optical scanner 300, a laser beam incident obliquely at an incident angle α with respect to the reflection surface 302 subjected to the mirror surface treatment is reflected on the reflection surface 120 by mirror reflection. Thus, the light is emitted in the same reflection angle β direction as the incident angle α.

  According to such a configuration, when a laser beam having a circular shape with a cross section 303 having a diameter a with respect to the traveling direction is incident on the reflection surface 302 of the conventional optical scanner 300, the incident region 304 of the laser beam is elliptical. The shape becomes larger than the cross section 303.

  Therefore, in the optical scanner 104 of the present embodiment, when a circular laser beam having the same diameter a is incident on the reflecting surface 120, the area of the reflecting surface 120 can be small, and the apparatus including the optical scanner 104 The whole can be downsized. Further, as shown in FIG. 7, by providing the reflecting mirror 86 and bending the optical path, the entire apparatus including the optical scanner 104 can be made thin.

  The above is a diffractive structure of the reflecting surface 120 so that the laser scanner 104 can be arranged so that the laser beam is incident on the reflecting surface 120 in the vertical direction and the emitted light 1 is emitted obliquely with respect to the reflecting surface 120. In addition, the formation of 401 has been described. In addition, as shown in FIG. 11, the laser beam is incident on the reflection surface 120 of the optical scanner 104 in an oblique direction at an incident angle α and is perpendicular to the reflection surface 120. The diffractive structure 401 of the reflecting surface 120 may be formed so as to be arranged in the direction. In addition, as shown in FIG. 12, with respect to the optical scanner 104, the laser beam is incident on the reflecting surface 120 in an oblique direction at an incident angle α, and the reflecting angle (diffraction angle) is different from the incident angle α with respect to the reflecting surface 120. ) The reflective surface 120 may be formed so as to be arranged in the direction of β.

  By using the diffraction structure 401 on the reflection surface of the optical scanner 104 in this way, the incident laser beam is reflected at a desired angle, and the image forming image light emitted from the optical scanner 104 is set in a desired direction. Can do.

  The diffractive structure 401 has a configuration in which the intensity of diffracted light of a specific order is made stronger than the intensity of diffracted light of other orders (for example, a blazed one-dimensional diffraction grating as shown in FIG. 8). Therefore, it is desirable to suppress a decrease in diffraction efficiency.

  Next, an example in which diffracted light of a specific order among the diffracted lights of a plurality of orders generated by the diffractive structure 401 is used as image light for image formation, and other orders of diffracted light are used will be described. Here, as an example, an example used to detect the swing position of the reflecting surface 120 of the optical scanner 104 (hereinafter referred to as “swing position detection”) will be described.

  FIG. 13 shows a diffractive structure 401 in which diffracted light of a specific order is emitted light 1 as image light for image formation, and the other diffracted light of another order is emitted light 2 as image light for detecting a swing position. FIG. 6 is a diagram schematically illustrating an example of an optical scanner 104 that employs the reflection surface 120 of FIG.

  As shown in FIG. 13, the laser beam incident in the direction perpendicular to the reflection surface 120 of the optical scanner 104 is reflected in different reflection directions as the outgoing light 1 and the outgoing light 2 by the reflective surface 120 having the diffractive structure 401. Divided. The emitted light 1 is sent to the next relay optical system 194 (not shown) as image light for image formation. On the other hand, the emitted light 2 is incident on a beam detector 200 provided at a fixed position. The beam detector 200 detects the scanning position of the emitted light 1 by detecting the emitted light 2 and detecting the swing position.

  The swing position detection by the beam detector 200 will be specifically described with reference to FIGS. As shown in FIG. 14, when the beam detector 200 detects the passage of the emitted light 2, the beam detector 200 outputs a signal indicating that the emitted light 2 has reached the installation position D of the beam detector 200 as a BD signal, and outputs the signal. The BD signal is supplied to a signal processing circuit 60 (not shown). As shown in FIGS. 14 and 15, in response to the BD signal output from the beam detector 200, the signal processing circuit 60 starts the forward image start position from the time when the beam detector 200 detects the emitted light 2 at the installation position D. After waiting for the set time t1 to reach point E, a necessary drive signal EF is supplied to each laser driver 70, 72, 74 (not shown).

  Thereafter, from when the outgoing light 2 passes the forward path image start position E, it passes through the backward path image start position F, turns back at the maximum backward path amplitude position C, and passes again through the backward path image start position F. Waiting for the set time t2 to elapse, the drive signal EF is supplied to the laser drivers 70, 72, 74 again. Since the scanning amplitude of the outgoing light 1 and the scanning amplitude of the outgoing light 2 are the same, the actual position of the outgoing light 1 as the image light is detected by such signal processing, and the image display start timing is further determined. The image display is started at the image display start timing. Therefore, the correspondence between the image signal and the laser beam scanning position is ensured.

  As shown in FIG. 16, the outgoing light 1 and the outgoing light 2 reflect a diffractive structure (eg, a hologram structure shown in FIG. 17) that is emitted as a condensed light whose beam diameter gradually decreases with respect to the traveling direction. The surface 120 may be adopted. By condensing the emitted light in this way, the emitted light amounts of the emitted light 1 and the emitted light 2 can be increased even when the incident light amount of the laser beam incident on the reflecting surface 120 of the optical scanner 104 is small. it can. Therefore, the emitted light 1 can be made clearer image light while suppressing the amount of incident light of the laser beam, and the oscillation position detection by the beam detector 200 can be made more reliable for the emitted light 2. Can do.

  On the other hand, as shown in FIG. 18, the reflecting surface 120 employs a diffractive structure that emits diffused light whose beam diameter gradually increases with respect to the traveling direction. Good. In this way, by using the emitted light as the diffused light, a wider range of image formation is possible for the emitted light 1. Further, with respect to the emitted light 2, it is possible to make the detection of the swing position by the beam detector 200 more reliable by increasing the incident light amount of the laser beam.

  The configuration of the diffractive structure 401 formed on the reflection surface 120 of the optical scanner 104 has been described above, but the present embodiment is not limited to such a configuration.

  By the way, as described above, the diffractive structure has a characteristic that the diffraction angle varies depending on the wavelength (color), and due to this characteristic, when a laser beam having a plurality of colors is incident on the reflection surface 120 of the optical scanner 104, Finally, a deviation occurs in the image formed on the retina 14 of the observer. Although this phenomenon is called chromatic aberration, three configurations for correcting chromatic aberration will be described below.

  First, a first configuration for correcting chromatic aberration using the diffraction structure 401 formed on the reflection surface 120 of the optical scanner 104 will be described with reference to FIG. FIG. 19A is an enlarged view of an arbitrary range Q portion on the reflection surface 120 of the optical scanner 104. As shown in FIG. 19A, in this embodiment, the diffractive structures 401 formed on the reflecting surface 120 of the optical scanner 104 are a diffractive structure R for red light, a diffractive structure G for green light, and a blue light, respectively. The diffraction structure B is divided into a plurality of diffraction structures B, and the diffraction structures R, G, and B are regularly arranged in this order. FIG. 19B is a cross-sectional view taken along the line PP of the optical scanner 104 in FIG. Further, a shielding plate 801 as a shielding unit that transmits only light in a specific direction is installed between the optical scanner 104 and a relay optical system 194 (not shown). Here, for simplicity of explanation, the outgoing light 2 is not shown, and only the outgoing light 1 is shown and described.

  The diffractive structures R, G, and B have different geometric shapes. When the laser beam is incident on the reflecting surface 120 in the vertical direction, the diffractive structure R has red light and the diffractive structure G has green light. In the diffractive structure B, the blue light is arranged to be emitted as the outgoing light 1 toward the next relay optical system 194 (not shown).

  Specifically, the laser beam incident on the diffractive structure R is only diffracted by the red light R1 in the red wavelength band among the three primary colors (red, green, and blue) constituting the laser beam to the relay optical system 194 by diffraction. The other light in the green and blue wavelength bands (referred to as green light G1 and blue light B1, respectively) is emitted in different directions without going to the relay optical system 194.

  The shielding plate 801 shields the green light G1 and the blue light B1, transmits only the red light R1, and sends it to the relay optical system 194.

  Similarly, in the laser beam incident on the diffractive structure G, only the green light G2 in the green wavelength band is emitted in the direction of the diffraction angle β by diffraction and passes through the shielding plate 801. In the laser beam incident on the diffractive structure B, only the blue light B3 in the blue wavelength band is emitted in the direction of the diffraction angle β by diffraction and passes through the shielding plate 801.

  That is, since the red light R1, the green light G2, and the blue light B3 are emitted in the same direction as the emitted light 1 through the shielding plate 801, the chromatic aberration is corrected.

  Therefore, since the emitted light 1 sent to the relay optical system 194 is used as image light for image formation in a state where chromatic aberration is corrected, higher-quality image formation is possible.

  On the other hand, in each diffractive structure, light emitted in a direction different from the emitted light 1 is shielded by the shielding plate 801 and is not sent to the subsequent relay optical system 194, so that a higher quality image is formed. Is possible.

  Next, a second configuration in which a separate optical system is provided to correct chromatic aberration will be described with reference to FIG.

  As shown in FIG. 20, in this embodiment, a chromatic aberration correcting optical system 901 is provided between the optical scanner and a relay optical system 194 (not shown). As the chromatic aberration correcting optical system 901, an achromatic lens combining prisms and lenses made of materials having different refractive indexes can be considered.

  As described above, the laser beam incident on the reflection surface 120 of the optical scanner 104 is emitted in the direction of a different diffraction angle for each light of a different wavelength (color) than the diffraction in the diffraction structure 401 formed on the reflection surface 120. (E.g., outgoing light 1 and outgoing light 2) pass through the chromatic aberration correction optical system 901 so that outgoing lights of different wavelengths are collimated and sent to the relay optical system 194.

  Therefore, the chromatic aberration of the laser beam is sent to the relay optical system 194 (not shown) in a state where the chromatic aberration is corrected through the chromatic aberration correcting optical system 901, so that high-quality image formation is possible.

  A diffractive optical element may be used as the chromatic aberration correcting optical system 901. Further, such a diffractive optical element may be provided on the reflection surface of the galvanometer mirror 210 as a second optical scanner disposed after the relay optical system 194. With this configuration, the laser beam is incident on the image plane of the retina 14 through the pupil 12 of the observer's eye 10 with the chromatic aberration corrected.

  Next, a third configuration for correcting chromatic aberration by changing the incident angle depending on the color will be described with reference to FIG.

  In the present embodiment, as shown in FIG. 21, the light source unit 20 ′ has the same configuration as the light source unit 20 except that it does not include the dichroic mirrors 50, 52, 54 and the coupling optical system 56. For simplicity, as shown in FIG. 21, in the light source unit 20 ′, configurations other than the lasers 30, 32, 34 and the collimating optical systems 40, 42, 44 are not shown.

  In addition, the light source unit 20 ′ is configured to emit each laser beam emitted from each laser 30, 32, 34 through collimating optical systems 40, 42, 44, and then emit it at independent angles. Yes.

  The laser beams emitted from the lasers 30, 32, and 34 are collimated through collimating optical systems 40, 42, and 44, reflected by the reflecting mirror 86, and reflected from the reflecting surface 120 of the optical scanner 104. Incident at different angles of incidence.

  Each laser beam incident on the reflection surface 120 of the optical scanner 104 at a different incident angle is emitted in a direction of a different diffraction angle for each laser beam by diffraction in the diffraction structure 401 formed on the reflection surface 120. .

  At this time, each of the lasers 30, 32, and 34 and the collimating optical systems 40, 42, and 44 adjust the incident angle when each laser beam is incident on the reflecting surface 120 of the optical scanner 104, and emit with the same diffraction angle β. It is installed in a position adjustable state.

  Therefore, by adjusting the positions of the lasers 30, 32, 34 and the collimating optical systems 40, 42, 44, the lasers 30, 32, 34 are emitted in the direction of the same diffraction angle β, so that chromatic aberration is corrected. can do.

  In addition to the above configuration, a coupling optical system, an optical fiber, and a collimating optical system may be disposed in this order after the collimating optical systems 40, 42, and 44, and each laser may be emitted from each collimating optical system. By using the optical fiber, it becomes easier to adjust the incident angle when each laser is incident on the reflecting surface 120 of the optical scanner 104.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and the knowledge of those skilled in the art including the aspects described in the section of [Means for Solving the Problems] is included. The present invention can be implemented in other forms based on various modifications and improvements. For example, the diffraction structure 401 may have various patterns. However, the diffraction structure 401 has a cross-sectional shape other than the blazed type detailed in the present embodiment (not shown), and a large number of linear grooves 412 are arranged in a lattice shape in parallel with each other. The provided one-dimensional diffraction grating 402 (FIG. 22) may be adopted. In addition, a two-dimensional diffraction grating 403 (FIG. 23) in which a plurality of linear grooves 413 provided in a lattice pattern parallel to each other at predetermined intervals is further intersected at right angles to form a grid pattern, and a large number of circular grooves 415 are concentric. A two-dimensional diffraction grating 405 (FIG. 24) arranged in a shape may be employed. By appropriately selecting these diffraction gratings as the diffraction structure 401, it is possible to reflect the incident laser beam at a desired angle and set the image light for image formation emitted from the optical scanner 104 in a desired direction. .

  The diffractive structure 401 is desirably formed integrally with a material such as silicon that is the same material as the oscillator 124. That is, as shown in FIG. 25A, the diffractive structure 401 is formed by applying a photosensitive resist 498 on a substrate 496 such as silicon on which the shape of the oscillator 124 is formed, and exposing it through a mask 497. After forming 499, as shown in FIG. 25B, unnecessary resist 498 is removed by wet or dry etching.

1 is a system diagram showing a retinal scanning display device including an optical scanner according to a first embodiment of the present invention. It is a perspective view shown in the state which assembled the optical scanner in FIG. It is a disassembled perspective view which shows the optical scanner in FIG. It is a longitudinal cross-sectional view which shows a part of rocking body in FIG. It is a perspective view which shows the rocking body in FIG. It is an enlarged view of the diffraction structure formed in the reflective surface of an optical scanner. It is a figure for demonstrating the structure which provides a reflective mirror and bends an optical path in an optical scanner. It is a figure for demonstrating the diffraction phenomenon in a diffraction structure. A state in which the diffraction structure of the reflection surface is formed so that the laser scanner can be arranged so that the laser beam is incident in a direction perpendicular to the reflection surface and the emitted light 1 is emitted in an oblique direction with respect to the reflection surface will be described. FIG. It is the figure which showed the structure of the conventional optical scanner. Regarding the optical scanner, the diffractive structure of the reflective surface is formed so that the laser beam is incident obliquely at an incident angle α with respect to the reflective surface of the optical scanner and emitted in a direction perpendicular to the reflective surface. It is a figure for demonstrating. The optical scanner is arranged so that the laser beam is incident on the reflecting surface in an oblique direction at an incident angle α and is emitted in a direction having a reflection angle (diffraction angle) β different from the incident angle α with respect to the reflecting surface. It is a figure for demonstrating the state in which the reflective surface was formed. It is the figure which represented typically the example of the optical scanner which employ | adopted the diffraction structure which divides | segments a laser beam as the reflective surface. It is the figure which showed the positional relationship of the scanning of the emitted light 2, and a beam detector. It is a figure for demonstrating the rocking | swiveling position detection by a beam detector. It is the figure which showed the optical scanner which employ | adopted the diffractive structure radiate | emitted as a condensing as a beam diameter becomes small gradually with respect to the advancing direction to a reflective surface. It is the figure which showed the hologram structure. It is the figure which showed the optical scanner which employ | adopted as a reflective surface the diffraction structure radiate | emitted as a diffused light from which a beam diameter becomes large gradually with respect to the advancing direction. It is a figure for demonstrating the 1st structure which correct | amends a chromatic aberration using the diffraction structure formed in the reflective surface of an optical scanner. It is a figure for demonstrating the 2nd structure which corrects chromatic aberration by providing an optical system separately. It is a figure for demonstrating the 3rd structure which correct | amends a chromatic aberration by changing an incident angle according to a color. It is the figure which showed the one-dimensional diffraction grating. It is the figure which showed the two-dimensional diffraction grating. It is the figure which showed the two-dimensional diffraction grating which provided many circular grooves arrange | positioned concentrically. It is a figure for demonstrating the manufacturing method of the diffraction structure using wet etching or dry etching.

Explanation of symbols

20 Light source unit 24 Scanning device 60 Signal processing circuit 100 Horizontal scanning system 102 Vertical scanning system 104 Optical scanner 120 Reflecting surface 122 Reflecting mirror unit 124 Oscillator 194 Relay optical system 200 Beam detector 401 Diffraction structure 601 Temperature sensor 602 Temperature control unit 801 Shielding Plate 901 Chromatic aberration correction optical system

Claims (21)

In the optical scanner that scans the reflected light from the reflecting surface by swinging the reflecting surface that reflects the incident light, the diffractive structure is formed on the reflecting surface ,
The diffractive structure is
A first diffractive structure that emits at least a first light flux having a predetermined wavelength of the incident light in a direction of a predetermined diffraction angle by diffraction;
A second light beam having a geometric shape different from that of the first diffractive structure and having a wavelength different from that of the first light beam out of the incident light is emitted in the direction of the predetermined diffraction angle by diffraction. Two diffraction structures,
An optical scanner comprising: The optical scanner according to claim 1, wherein the diffractive structure is a structure in which the intensity of diffracted light of a specific order is made stronger than the intensity of diffracted light other than the specific order. The optical scanner according to claim 1, further comprising an oscillating body that oscillates together with the reflecting surface for the scanning, wherein the diffractive structure is made of the same material as the oscillating body. The optical scanner according to claim 3, wherein the diffractive structure is formed by wet etching or dry etching. The optical scanner according to claim 1, further comprising an oscillating body that oscillates with the reflecting surface for the scanning, wherein the diffractive structure is formed of a material different from that of the oscillating body. The diffractive structure is a nanoimprint in which a resin film is formed on the oscillator, and a mold having a fine uneven pattern is pressed against the resin film to transfer the uneven pattern of the mold to the resin film. The optical scanner according to claim 5 formed by a method. The optical scanner according to claim 1, wherein the diffraction structure is a one-dimensional diffraction grating structure. The optical scanner according to claim 1, wherein the diffraction structure is a two-dimensional diffraction grating structure. The optical scanner according to claim 1, wherein the diffractive structure is a hologram structure that collects or diffuses the incident light. The optical scanner according to claim 8 or 9, wherein the diffractive structure is a structure that divides the incident light into a plurality of reflected lights of a diffracted light of a specific order and a diffracted light of another order . An image forming apparatus that forms an image by scanning a light beam according to an image signal,
A light source that emits the luminous flux;
An image forming apparatus comprising: the optical scanner according to claim 1; and a scanning unit configured to scan a light beam emitted from the light source by the optical scanner. An image forming apparatus that forms an image by scanning a light beam according to an image signal,
A light source that emits the luminous flux;
11. The optical scanner according to claim 10, wherein a light beam emitted from the light source by scanning of the optical scanner is divided into at least two light beams, and at least one of the divided light beams is in a predetermined scanning direction. A scanning unit that scans
A photodetector that is disposed within the scanning range by the optical scanner and detects passage of light beams other than a predetermined scanning direction among the divided light beams;
An image forming apparatus comprising: a control unit that controls timing of emitting the light beam from the light source based on a detection signal from the photodetector. An image forming apparatus that forms an image by scanning a light beam according to an image signal,
A light source that emits the luminous flux;
A scanning unit comprising the optical scanner according to any one of claims 1 to 9 , wherein the optical scanner scans a light beam emitted from the light source,
An image forming apparatus comprising: a shielding unit configured to transmit at least the first light beam among the light beams scanned by the scanning unit and shield light beams other than the first light beam adjacent to the first light beam. The optical scanner is incident perpendicularly to the light beam to the reflecting surface, according to any one of claims 13 claim 11, which is positioned to exit in an oblique direction with respect to the reflecting surface Image forming apparatus. The optical scanner is incident obliquely to the light beam to the reflecting surface, according to any one of claims 13 claim 11, which is positioned to exit in a direction perpendicular to the reflecting surface Image forming apparatus. The light scanner according to claim a wherein the light beam from claim 11 incident in an oblique direction, are arranged in a position to emit in a direction having a different angle of reflection with angle of incidence with respect to the reflecting surface with respect to the reflecting surface The image forming apparatus according to claim 13 . Wherein the light flux emitted from the light source, with respect to the reflecting surface of the optical scanner, in any one of claims 16 claim 11 having an optical system that emits at different angles of incidence for each wavelength of the light beam Image forming apparatus. The image forming apparatus according to claims 11 having an optical system in any one of claims 16 to correct chromatic aberration caused by the reflection of the light beam in the optical scanner based on the wavelength difference of the light beam emitted from the light source. The image forming apparatus according to claim 18 , wherein the optical system that corrects the chromatic aberration includes a diffractive optical element. The image forming apparatus according to claim 19 , wherein the diffractive optical element is provided on a reflection surface of a second optical scanner provided at a subsequent stage of the optical scanner. 21. The retinal scanning image display device according to any one of claims 11 to 20 , wherein the image forming device is a retinal scanning image display device that projects and displays an image by guiding a light beam scanned by the optical scanner onto a retina of an eye. Image forming apparatus.

Images