JPWO2009057522A1 - Scanning projector - Google Patents

Abstract

In the scanning projection device (PJ), the light emitted from the light source device (1) is two-dimensionally deflected by the deflecting element (3), and is obliquely applied to the screen (SC) via the projection optical system (7). Project. The projection optical system (7) has a plurality of reflecting surfaces (S5, S8) and a refracting surface (S6). By appropriately setting the surface shape of each optical surface of the projection optical system (7), the reflective surface (S8) arranged closest to the screen (SC) has a function of correcting trapezoidal distortion, and the refractive surface ( S6) is provided with a field curvature correction function. As a result, in a scanning projection apparatus (PJ) that performs oblique projection, both the trapezoidal distortion and the curvature of field are corrected well while reducing the size of the entire apparatus, and a good image is formed over the entire screen.

Description

  The present invention is applied to pocket projectors, data projectors, rear projection televisions, and the like, and is a small scanning projection that displays an image on a scanned surface by deflecting a light beam two-dimensionally and scanning the scanned surface. It relates to the device.

  2. Description of the Related Art Conventionally, a projector using a light modulation element such as a DMD (Digital Micromirror Device; manufactured by Texas Instruments Inc.) or a liquid crystal element is known as a small projection apparatus. A method of enlarging and projecting an image displayed by the light modulation element is called a so-called micro display method. In a micro-display projector, an illumination optical system and a projection optical system are large in order to project a two-dimensional image, so that there is a limit to downsizing the apparatus.

  In contrast, in recent years, so-called laser scanning projectors have been actively developed. The laser scanning method is to scan the surface to be scanned by deflecting the laser light with a small mirror such as a MEMS (Micro Electro Mechanical Systems) mirror while modulating the output of the laser light emitted from the light source. In this method, an image is projected (displayed) on a surface. The laser scanning projector has (1) a scanning mirror that is smaller than a DMD or the like, and (2) a light source is a laser light source, and only irradiates the scanning mirror with a laser beam, so the illumination optical system is also reduced ( 3) Since the surface to be scanned is simply scanned with spots (light spots), the projection optical system has various advantages such as being smaller than the two-dimensional projection optical system, and the entire apparatus can be downsized. .

  For example, Patent Documents 1 and 2 disclose small projection apparatuses that employ a laser scanning method. In these projection apparatuses, a galvanometer mirror or a MEMS mirror is used as the optical scanning unit, and the light flux from the optical scanning unit is projected obliquely with respect to the screen. By driving the galvanometer mirror and the MEMS mirror to resonance, it is possible to scan the surface to be scanned by driving these mirrors at high speed and with a large amplitude (mechanical deflection angle). Further, the scan image can be shifted upward by oblique projection, and the scan image can be displayed at a position that is easy for the observer to see. Further, when a scanning image display device equipped with a projection device is placed on a desk, it is possible to display all the scanned images on the screen without displaying them on the desk.

JP 2006-178346 A JP 2005-234157 A

  By the way, in a projector that performs oblique projection, a trapezoidal distortion in which the upper side of the screen becomes larger than the lower side as the oblique projection angle becomes larger appears prominently. At this time, in a micro-display projector, the image display element (light modulation element) and the surface to be scanned (screen surface) are brought close to the so-called Scheinproof relationship, thereby correcting trapezoidal distortion even when the oblique projection angle is large. Is possible.

  On the other hand, in a laser scanning projector, there is no image display element conjugate with the screen surface, and the light beam emitted from the light source is incident on an optical member having a positive power and is then stopped near the deflection member. Then, the light enters the deflecting member while converging, and is then guided to the screen by a projection optical system having negative power. In such a configuration, in addition to the above trapezoidal distortion, curvature of field occurs due to the fact that the optical path length varies depending on the height of the screen during oblique projection.

  However, Patent Documents 1 and 2 do not describe any technique for forming a good image on the screen by appropriately correcting the curvature of field while appropriately correcting the trapezoidal distortion caused by the oblique projection. . In a laser scanning projector, it is desirable to achieve both correction of trapezoidal distortion and correction of curvature of field without impairing the advantage that the entire apparatus can be reduced in size.

  The present invention has been made to solve the above-described problems, and its object is to correct both trapezoidal distortion and field curvature in a configuration in which oblique projection is performed. Accordingly, it is an object of the present invention to provide a scanning projection apparatus capable of forming a good image over the entire screen while reducing the size of the entire apparatus.

  The scanning projection apparatus of the present invention includes a light source means, a deflection member that deflects light emitted from the light source means in a first scanning direction and a second scanning direction orthogonal to each other, and light deflected by the deflection member. A projection optical system that guides the light to the surface to be scanned, and two-dimensionally scanning the surface to be scanned with the light, wherein the first scanning direction is a screen short side direction of the surface to be scanned The projection optical system has a plurality of reflecting surfaces and a refracting surface, and the light incident on the upper and lower ends of the screen on a cross section perpendicular to the surface to be scanned including the screen center principal ray. Among them, when a light beam having a smaller incident angle with respect to the screen is a first light beam and a light beam having a larger incident angle with respect to the screen is a second light beam, the light beam is arranged closest to the scanned surface among the plurality of reflecting surfaces. Second run at the first intersection position of the reflecting surface and the first light ray Direction of curvature is positive, and is characterized in that than the second curvature in the scanning direction at the second intersection between the reflecting surface and the second light beam, positive curvature is large.

In the scanning projection apparatus of the present invention, the reflecting surface arranged closest to the surface to be scanned is symmetrical with respect to a cross section perpendicular to the surface to be scanned including the center principal ray of the screen and is convex in the second scanning direction. It is desirable to have a region satisfying the following conditional expression (1). That is,
| Φ1 / φ2 | <0.8 (1)
However,
φ1: curvature in the first scanning direction on the symmetry plane
φ2: curvature in the second scanning direction on the symmetry plane.

It is desirable that the scanning projection apparatus of the present invention satisfies the following conditional expression (2) at the first intersection position. That is,
| Φ1 / φ2 | <0.2 (2)
It is.

  In the scanning projection device of the present invention, the curvature in the second scanning direction at the intersection point between the reflection surface arranged closest to the deflection member among the plurality of reflection surfaces and the first light beam is negative, In addition, it is desirable that the curvature in the second scanning direction is larger in the negative direction at the intersection position between the reflection surface arranged closest to the deflection member and the second light beam.

  In the scanning projection apparatus of the present invention, the absolute value of the curvature in the second scanning direction at the first intersection position between the reflecting surface arranged closest to the surface to be scanned and the first light beam is the projection optical system. It is desirable that the absolute value of the curvature in the second scanning direction at each of the intersection positions of the other reflecting and refracting surfaces and the first light beam is larger.

  In the scanning projection apparatus of the present invention, the reflecting surface arranged closest to the surface to be scanned is a non-rotationally symmetric surface and symmetric with respect to a cross section perpendicular to the surface to be scanned including the principal ray at the center of the screen. The absolute value of the curvature in the second scanning direction on the reflection surface increases as the distance from the symmetry surface in the second scanning direction increases in the region where the light beam including the first light beam and the reflection surface intersect. It is desirable to become.

  In the scanning projection apparatus of the present invention, it is desirable that the optical path of the projection optical system is folded by a plurality of reflecting surfaces in a cross section perpendicular to the surface to be scanned including the screen center principal ray.

  In the scanning projection apparatus of the present invention, the refractive surface is preferably a non-rotationally symmetric free-form surface.

  In the scanning projection apparatus of the present invention, it is preferable that the curvature in the second scanning direction is negative at the intersection point between the refractive surface and the first light beam.

  In the scanning projection apparatus according to the aspect of the invention, it is preferable that the refracting surface is disposed between a reflecting surface disposed closest to the surface to be scanned and a reflecting surface disposed closest to the deflection member.

  In the scanning projection apparatus according to the aspect of the invention, in the region where the light beam including the second light beam and the reflection surface arranged closest to the surface to be scanned intersect, the reflection is performed as the distance from the symmetry surface increases in the second scanning direction. It is desirable that the curvature in the second scanning direction on the surface changes in the negative direction.

  The scanning projection apparatus of the present invention may further include an optical member that guides the light emitted from the light source means to the deflecting member, and the optical member may have a positive power.

  In the scanning projection apparatus of the present invention, the optical member may have anamorphic power.

  According to the present invention, by setting the curvature of the reflecting surface disposed closest to the scanning surface in the projection optical system as described above, the second incident light beam obliquely incident on, for example, the lower side of the screen is scanned. It becomes possible to correct the trapezoidal distortion by spreading in the scanning direction. In addition, by introducing a refracting surface into the projection optical system, it is possible to correct the curvature of field with a small power while forming the projection optical system compactly with a plurality of reflecting surfaces. In other words, according to the present invention, in a configuration in which oblique projection is performed, both aberrations are favorably corrected while miniaturizing the entire apparatus by providing different correction functions for the reflection surface and the refractive surface of the projection optical system. And a good image can be formed over the entire screen.

1 is a vertical sectional view schematically showing an overall configuration of a scanning projection apparatus according to Embodiment 1 of the present invention. It is a vertical sectional view schematically showing the configuration of the main part of the scanning projection apparatus. It is a vertical sectional view schematically showing the overall configuration of a scanning projection apparatus according to Embodiment 2 of the present invention. It is a vertical sectional view schematically showing the configuration of the main part of the scanning projection apparatus. It is a vertical sectional view schematically showing the overall configuration of a scanning projection apparatus according to Embodiment 3 of the present invention. It is a vertical sectional view schematically showing the configuration of the main part of the scanning projection apparatus. It is a top view which shows the schematic structure of the deflection | deviation element used for the scanning projection apparatus of each Embodiment 1-3. It is sectional drawing of the said deflection | deviation element. It is sectional drawing of the said deflection | deviation element. It is sectional drawing of the said deflection | deviation element. It is sectional drawing of the said deflection | deviation element. It is sectional drawing of the said deflection | deviation element. It is explanatory drawing which shows the surface shape of S5 surface in Example 1. FIG. It is explanatory drawing which shows the surface shape of S6 surface in Example 1. FIG. It is explanatory drawing which shows the surface shape of S8 surface in Example 1. FIG. It is explanatory drawing which shows the surface shape of S5 surface in Example 2. FIG. It is explanatory drawing which shows the surface shape of S6 surface in Example 2. FIG. It is explanatory drawing which shows the surface shape of S8 surface in Example 2. FIG. It is explanatory drawing which shows the surface shape of S5 surface in Example 3. FIG. It is explanatory drawing which shows the surface shape of S6 surface in Example 3. FIG. It is explanatory drawing which shows the surface shape of S8 surface in Example 3. FIG. It is explanatory drawing which shows the surface shape of S5 surface of Example 1 except an inclination component. It is explanatory drawing which shows the surface shape of S5 surface of Example 2 except an inclination component. It is explanatory drawing for demonstrating the definition of a curvature. 6 is an explanatory diagram illustrating distortion of a two-dimensional projection image in Embodiment 1. FIG. It is explanatory drawing which shows the distortion of the two-dimensional projection image in Example 2. FIG. It is explanatory drawing which shows the distortion of the two-dimensional projection image in Example 3. FIG. It is explanatory drawing which shows trapezoid distortion. It is explanatory drawing which shows TV distortion.

Explanation of symbols

1 Light source device (light source means)
2 Incident optical system 3 Deflection element (deflection member)
4 First Reflection Mirror 5 Refractive Lens 6 Second Reflection Mirror 7 Projection Optical System PJ Scanning Projector SC Screen (Scanned Surface)
P1 Intersection position P2 Intersection position Q1 Intersection position Q2 Intersection position R1 Intersection position (first intersection position)
R2 intersection position (second intersection position)

Embodiments of the present invention will be described below with reference to the drawings.
(1. Overall configuration of scanning projection apparatus)
FIG. 1 is a vertical sectional view schematically showing the overall configuration of the scanning projection apparatus PJ according to the first embodiment, and FIG. 2 schematically shows the configuration of the main part of the scanning projection apparatus PJ in FIG. FIG. FIG. 3 is a vertical sectional view schematically showing the overall configuration of the scanning projection apparatus PJ according to the second embodiment. FIG. 4 schematically shows the configuration of the main part of the scanning projection apparatus PJ in FIG. FIG. Further, FIG. 5 is a vertical sectional view schematically showing the overall configuration of the scanning projection apparatus PJ according to Embodiment 3, and FIG. 6 schematically shows the configuration of the main part of the scanning projection apparatus PJ of FIG. FIG.

  Here, the short side direction of the screen displayed on the screen SC that is the surface to be scanned is the vertical direction, and the long side direction of the screen is the horizontal direction. On the screen SC, the screen short side direction is the y direction, the screen long side direction is the x direction, and the direction perpendicular to the screen is the z direction. The short side direction of the screen coincides with a first scanning direction by a deflecting element 3 described later, and the long side direction of the screen coincides with a second scanning direction by the deflecting element 3. Therefore, the first scanning direction and the second scanning direction are orthogonal to each other.

  Each of the scanning projection apparatuses PJ according to the first to third embodiments includes a light source device 1, an incident optical system 2, a deflection element 3, and a projection optical system 7.

  The light source device 1 is a light source unit having a light source that emits laser beams of three colors of RGB and a color synthesis unit. The light sources that emit R light and B light are each composed of a semiconductor laser, and the light sources that emit G light are composed of a semiconductor-excited solid-state laser. The center wavelength of the RGB laser light is, for example, 630 nm (R light), 532 nm (G light), and 445 nm (B light). The color synthesizing means synthesizes and emits the optical paths of the RGB laser beams, and is composed of, for example, a dichroic prism or a dichroic mirror.

  The incident optical system 2 is a condensing optical system that guides the light emitted from the light source device 1 to the deflecting element 3, and is composed of a lens whose light incident side is an anamorphic surface and whose light emission side is a plane. That is, the lens is an anamorphic lens having different curvatures in the vertical direction and the horizontal direction. In particular, the lens has a positive power in the horizontal direction. Therefore, the light emitted from the light source device 1 passes through the incident optical system 2 and enters the deflecting element 3 as convergent light in the horizontal direction and substantially parallel light in the vertical direction. In this way, by using an anamorphic lens as the incident optical system 2, light having different light beam diameters (light beam widths) in the vertical direction and the horizontal direction can be incident on the deflecting element 3.

  The deflection element 3 is a two-dimensional deflection member that deflects the light emitted from the light source device 1 and incident through the incident optical system 2 in the horizontal direction and the vertical direction, and is configured by, for example, a MEMS mirror. The details of the deflection element 3 will be described later. The deflection element 3 is sinusoidally driven (high-speed resonance driving) in the horizontal direction and linearly driven (low-speed driving) in the vertical direction.

  As the deflecting element 3, it is preferable to use a single element that can simultaneously realize horizontal driving and vertical driving. By using such a deflection element 3, the number of scanning means can be reduced to reduce the cost, and the labor for adjustment can be greatly reduced. Further, since the deflection element 3 that deflects incident light two-dimensionally is smaller than a light modulation element (for example, LCD or DMD) that has an image display area two-dimensionally, the projection optics downstream of the deflection element 3 is used. The system 7 can also be configured small. Therefore, by using such a deflection element 3, the entire apparatus can be reduced in size.

  The projection optical system 7 is an optical system that guides the light deflected by the deflecting element 3 to the screen SC. The projection optical system 7 has a negative power as a whole and has a role of enlarging the screen size, trapezoidal distortion, and field curvature described later. It plays the role of correction. The projection optical system 7 includes a first reflection mirror 4, a refractive lens 5, and a second reflection mirror 6.

  The first reflecting mirror 4 reflects the light deflected by the deflecting element 3 and guides it to the refractive lens 5, and is composed of a mirror having a non-rotationally symmetric XY free curved surface shape.

  The refracting lens 5 is a refracting member that refracts the light reflected by the first reflecting mirror 4 and guides it to the second reflecting mirror 6. The light incident side is a non-rotationally symmetric free-form XY curved surface, and the light exit side is flat. It consists of a lens. By disposing the refractive lens 5 between the first reflecting mirror 4 and the second reflecting mirror 6, the configuration of the apparatus can be made compact. Although the refractive lens 5 has power only on the light incident side, it may have power only on the light emission side, and may have power on both sides.

  The second reflecting mirror 6 reflects light incident from the first reflecting mirror 4 via the refractive lens 5 and guides it to the screen SC, and is composed of a mirror having a non-rotationally symmetric XY free-form surface shape. .

  According to the above configuration, when an image signal is input from the image input device (not shown) to the scanning projection device PJ, the scanning projection device PJ uses the image processing circuit (not shown) to deflect the deflection element 3. The deflection angle of the mirror and the output of each RGB laser beam corresponding to the mirror deflection angle are calculated. Then, based on an instruction from the image processing circuit, the deflection element 3 is driven, and at the same time, the output (luminance, light amount) of RGB laser light in the light source device 1 is modulated.

  The light emitted from the light source device 1 enters the deflection element 3 via the incident optical system 2 and is deflected there in the horizontal direction and the vertical direction. The light deflected by the deflecting element 3 is projected onto the screen SC through the first reflecting mirror 4, the refractive lens 5, and the second reflecting mirror 6 in this order. Therefore, by modulating the light output, the light is two-dimensionally deflected by the above-described two-dimensional drive of the deflecting element 3, and the screen SC is scanned two-dimensionally with the light. The image can be displayed two-dimensionally.

  At this time, if the maximum output of the RGB laser light is 150 mW, 120 mW, and 83 mW, respectively, it is possible to obtain a very vivid screen with a beautiful white color and a wide color reproduction region. In this case, the output value from the light source device 1 is about 100 lumens, and the loss due to the optical system (surface reflection loss, loss due to MEMS time control, loss due to color synthesis means, etc.) is 50% in total. Therefore, it is possible to realize a scanning projection apparatus PJ having a brightness of 50 lumens.

  The G laser light modulation method may be direct modulation of an excitation laser (including a method in which a second harmonic is generated by a PPLN (Periodically Poled Lithium Niobate) waveguide) or an acoustooptic device ( Although external modulation such as an AO (Acousto-Optics) element may be used, the former method is preferable in that an AO element is not required.

  By the way, in each of Embodiments 1 to 3, in order to display a color image on the screen SC, the light from the three RGB light sources is synthesized and projected onto the screen SC via the projection optical system 7. . At this time, if chromatic aberration (magnification chromatic aberration, axial chromatic aberration) occurs, color blurring occurs and image performance deteriorates. Therefore, the projection optical system 7 needs to be an optical system in which chromatic aberration is suppressed. At this time, if the projection optical system 7 is configured by using a refractive lens having a large power, chromatic aberration is greatly generated and it becomes difficult to correct. Therefore, it is preferable to configure the projection optical system 7 using a reflection optical system that does not generate chromatic aberration, or a refractive lens that generates little chromatic aberration and has low power.

  When the projection optical system 7 is constituted by a reflection optical system, it is necessary to arrange the deflecting element 3 so as to separate the incident light beam and the reflected light beam, but the light beam separation direction in the projection optical system 7 is vertical. The direction is preferred. This is because the normal display screen is often a horizontally long screen such as 4: 3 or 16: 9, and light separation in the direction along the short side is easier to separate, and the whole can be made smaller. is there. In addition, projectors such as projectors usually project from a front lower side to a projection surface such as a screen, but one reason is that if they are separated in the vertical direction, oblique projection from the lower side is easier. It is.

  In each of the first to third embodiments, the light beam is incident on the deflecting element 3 at an angle in the vertical direction. By making the light beam obliquely incident on the deflecting element 3 in this way, there is little decrease in the deflectable light beam width due to the change in the direction of the deflecting surface (reflecting surface) of the deflecting element 3, and the light amount loss due to the deflection is reduced. It becomes possible to reduce.

  In each of the first to third embodiments, the incident optical system 2 is composed of an optical member (anamorphic lens) having a positive power. Thereby, after converging the light beam emitted from the light source device 1 on the deflecting element 3, the light can be enlarged and projected onto the screen SC by the projection optical system 7 having negative power. That is, it is possible to enlarge the screen size by widening the angle of view. Further, since the lens has anamorphic power, the spot shape on the screen SC is good (for example, true) even when the power of the projection optical system 7 is different between the horizontal direction and the vertical direction. Yen).

(2. Details of deflection element)
Next, details of the deflection element 3 will be described.
FIG. 7 is a plan view showing a schematic configuration of the deflection element 3. 8A to 8E are cross-sectional views when the deflection element 3 of FIG. 7 is cut along a cross section parallel to the Y axis. The deflection element 3 is a MEMS mirror having a mirror unit 10, a movable frame 30 and a fixed frame 70. The fixed frame 70 is a part for fixing the deflection element 3 to a housing (not shown), and the movable frame 30 is formed in a frame shape as a movable part inside the fixed frame 70. The mirror part 10 is formed in a square shape inside.

  The mirror unit 10 forms a reflection surface that deflects light from the light source device 2 in a two-dimensional manner, and the torsion bar 21 extends outward along the Y axis passing through the center of the mirror unit 10 from two opposing sides. 22 is elastically supported by the movable frame 30 from both sides. The movable frame 30 is perpendicular to the torsion bars 21 and 22 and is bent from the opposite sides to the fixed frame 70 by curved beams 41 to 44 each having one end connected in the vicinity of the X axis 30a to 30d passing through the center of the mirror portion 10. Elastically supported. The mirror part 10, the torsion bars 21 and 22, the movable frame 30, the bending beams 41 to 44, and the fixed frame 70 are integrally formed by anisotropic etching of a silicon substrate.

  Piezoelectric elements 51 to 54 are attached to the surfaces of the bending beams 41 to 44 by bonding or the like, so that four unimorph parts 61 to 64 are formed. As shown in FIG. 8A, an upper electrode 51a and a lower electrode 51b are provided on the front and back sides of the piezoelectric element 51, and an upper electrode 52a and a lower electrode 52b are provided on the front and back sides of the piezoelectric element 52, respectively. ing. Similarly, upper and lower electrodes are provided on the front and back surfaces of the piezoelectric elements 53 and 54, respectively.

  For example, when an AC voltage is applied to the upper electrode 51a and the lower electrode 51b within a range that does not cause polarization inversion, the piezoelectric element 51 expands and contracts and displaces in the thickness direction in a unimorph manner. Therefore, by bending deformation of the piezoelectric elements 51 to 54 caused by voltage application to each electrode, the bending beams 41 to 44 act on the movable frame 30 with independent rotational torque about the Y axis and the X axis, thereby The movable frame 30 can be rotated about the Y axis and the X axis as two axes. Hereinafter, details of such a rotation operation will be described.

  First, the rotation operation around the X axis will be described. In the state of FIG. 8A in which the piezoelectric elements 51 and 52 are not expanded or contracted, a voltage in the extending direction is applied to the piezoelectric element 51, and a voltage in the contracting direction is applied to the piezoelectric element 52 (the phase opposite to the applied voltage to the piezoelectric element 51). Voltage). Then, since one end of each unimorph part 61 * 62 is being fixed and hold | maintained at the fixed frame 70, while the unimorph part 61 bends so that the other end may be displaced below as shown in FIG. 8B, the unimorph part 62 Bends so that the other end is displaced upward.

  Similarly, when a voltage having the same phase as the voltage applied to the piezoelectric elements 51 and 52 is applied to the piezoelectric elements 53 and 54, one end of each unimorph portion 63 and 64 is fixed and held on the fixed frame 70. Therefore, the unimorph portion 63 is bent so that the other end is displaced downward, while the unimorph portion 64 is bent so that the other end is displaced upward. Thereby, rotational torque about the X axis acts on the movable frame 30, and the movable frame 30 tilts in one direction (P direction) about the X axis. Further, when a voltage having an opposite phase to the above is applied to the piezoelectric elements 51 to 54, a reverse rotational torque about the X axis acts on the movable frame 30, as shown in FIG. It tilts in the opposite direction (Q direction) around the axis.

  When an alternating voltage maintaining the above phase relationship is applied to the piezoelectric elements 51 to 54, the unimorph parts 61 to 64 follow the alternating voltage and repeat vertical vibrations, and a seesaw-like rotational torque acts on the movable frame 30, The movable frame 30 rotates and vibrates up to a predetermined displacement angle about the X axis. Since the widths of the portions 30a to 30d where the unimorph portions 61 to 64 are connected to the movable frame 30 are narrow, they are more easily bent than the other portions. For this reason, with the slight bending of the unimorph parts 61 to 64, as shown in FIGS. 8B and 8C, the vicinity of the X axis of the movable frame 30 is greatly inclined, and the mirror part 10 can be greatly inclined. The connecting portions 30a to 30d may be thinner than other portions in addition to narrowing the width.

  Next, the rotation operation around the Y axis will be described. When a voltage in the extending direction is applied to both of the piezoelectric elements 51 and 52, one end of the unimorph portions 61 and 62 is fixed and held on the fixed frame 70. Therefore, as shown in FIG. 8D, the unimorph portions 61 and 62 are In either case, the other end is bent so as to be displaced downward. On the other hand, when a voltage having a phase opposite to that of the piezoelectric elements 51 and 52 (voltage in a contracting direction) is applied to the piezoelectric elements 53 and 54, one end of the unimorph parts 63 and 64 is fixed and held by the fixed frame 70. As shown in 8E, both unimorph parts 63 and 64 bend so that the other end is displaced upward. In FIG. 8E, the mirror unit 10 is not shown for convenience. As a result, rotational torque about the Y axis acts on the movable frame 30, and the movable frame 30 tilts about the Y axis.

  When an alternating voltage maintaining the above phase relationship is applied to the piezoelectric elements 51 to 54, the unimorph parts 61 to 64 follow the alternating voltage and repeat vertical vibrations, and a seesaw-like rotational torque acts on the movable frame 30, The movable frame 30 rotates and vibrates up to a predetermined displacement angle about the Y axis. Therefore, by applying predetermined voltages to the four unimorph parts 61 to 64, the inclination of the mirror part 10 supported by the movable frame 30 about the X axis and the Y axis can be arbitrarily controlled.

(3. About Example)
Next, examples of the scanning projection apparatuses PJ of the first to third embodiments will be described more specifically with reference to construction data and the like as Examples 1 to 3. Then, correction of trapezoidal distortion and curvature of field will be described with reference to the optical surfaces shown in Examples 1 to 3. In addition, Examples 1-3 are numerical examples corresponding to the first to third embodiments, respectively, and optical configuration diagrams (FIGS. 1 to 6) representing the first to third embodiments are the corresponding implementations. The same applies to Examples 1 to 3.

  In the construction data shown below, Si (i = 1, 2, 3,...) Indicates the i-th surface counted from the light source device 1 side. The arrangement of each surface Si is specified by each surface data of surface vertex coordinates (x, y, z) and rotation angle (X rotation tilt). The surface vertex coordinates of the surface Si are the local orthogonal coordinate system (X, Y, z) in the global orthogonal coordinate system (x, y, z) with the surface vertex as the origin of the local orthogonal coordinate system (X, Y, Z). , Z) is expressed by the coordinates (x, y, z) of the origin (unit is mm), and the inclination of the surface Si is at a rotation angle (X rotation) about the X axis centered on the surface vertex. (The unit is degrees, and the counterclockwise direction when viewed from the positive direction of the X axis is the positive direction of the rotation angle of the X rotation). However, the coordinate systems are all defined by the right-handed system, and the global orthogonal coordinate system (x, y, z) is an absolute value that matches the local orthogonal coordinate system (X, Y, Z) of the aperture plane (S3). It is a coordinate system.

  In addition, the aperture diameter on an aperture surface is (PHI) 1mm in each of Examples 1-3. Further, RX and RY indicate the radii of curvature (mm) in the X direction and the Y direction, respectively, and Nd and νd indicate the Abbe numbers in the refractive index with respect to the d line, respectively.

  Further, the surface Si composed of a non-rotationally symmetric free-form surface is defined by the following equation 1 using a local orthogonal coordinate system (X, Y, Z) having the surface vertex as the origin.

However, in Equation 1, z indicates the amount of displacement in the Z-axis direction at the position of the height r (surface vertex reference), c indicates the curvature at the surface vertex (= 1 / radius of curvature (mm)), k represents a conic coefficient, and c (i, j) represents an i-order of X and a j-order free-form surface coefficient of Y. In each example, c (i, j) is described as XiYj. In addition, the coefficients of the terms not described are all 0, and E−n = × 10 ⁻ⁿ is set for all data.

Example 1

S5 surface: free-form surface

S6 surface: free-form surface

S8 surface: free-form surface

(Example 2)

S5 surface: free-form surface

S6 surface: free-form surface

S8 surface: free-form surface

(Example 3)

S5 surface: free-form surface

S6 surface: free-form surface

S8 surface: free-form surface

  9 to 11 show the surface shapes of the S5 surface, the S6 surface, and the S8 surface in Example 1, respectively. 9 to 11, the numerical values in the X direction and the Y direction indicate values in local coordinates, and the numerical values in the Z direction are based on the incident position of the screen center principal ray as a reference (0 mm). The amount of deviation (variation) in the Z direction is shown. The screen center principal ray refers to a light beam emitted from the light source device 1 and passing through the center of the stop (S3 surface on the deflection element 3) and entering the screen center of the screen SC.

  12 to 14 show the surface shapes of the S5 surface, the S6 surface, and the S8 surface in Example 2, respectively. FIGS. 15 to 17 show the surface shapes of the S5 surface, the S6 surface, and the S8 surface in Example 3, respectively. The manner of illustration in these drawings is exactly the same as in FIGS. 9 to 11 relating to the first embodiment.

  FIG. 18 shows the surface shape of the S5 surface of Example 1 shown in FIG. 9 excluding the inclination component (component including the first-order term of Y). Similarly, FIG. 19 shows the surface shape of the S5 surface of the second embodiment shown in FIG. 12 excluding the tilt component. The free-form surface shape of FIGS. 9 and 12 has a surface inclination, and since the surface undulation amount is small with respect to the inclination, the undulation amount is buried. 18 and 19 more clearly represent the undulation of the surface by removing the tilt component from the free-form surface shape of FIGS. 9 to 19, light rays enter from the upper side of the surface.

(4. Correction of keystone distortion and field curvature)
Hereinafter, correction of trapezoidal distortion and curvature of field will be described with reference to the surface shapes of the optical surfaces shown in FIGS. For convenience of explanation below, P1, P2, Q1, Q2, R1, and R2 are respectively defined as follows.

  That is, among the light rays incident on the upper and lower ends of the screen on the cross section (yz plane) perpendicular to the screen SC including the screen center principal ray, the light ray A (first light ray; the first light ray; FIGS. 5) and the intersection position between the S5 surface (that is, the reflective surface arranged closest to the deflection element 3 among the multiple reflective surfaces of the projection optical system 7) is defined as P1. Of the light rays incident on the upper and lower ends of the screen on the cross section, the intersection position of the light beam B (second light beam; see FIGS. 1, 3, and 5) having a larger incident angle with respect to the screen and the S5 plane is P2. And The cross section perpendicular to the screen SC including the screen center chief ray is also a cross section including the screen center chief ray and parallel to the short side direction of the screen.

  Further, the intersection position of the light beam A incident on the screen on the cross section and the S6 surface (that is, the refractive surface of the projection optical system 7) is defined as Q1. The intersection position between the light beam B incident on the screen and the S6 surface on the cross section is defined as Q2. On the other hand, the intersection position of the light ray A incident on the screen on the cross section and the S8 surface (that is, the reflective surface arranged closest to the screen SC among the plurality of reflective surfaces of the projection optical system 7) is R1 ( First intersection point position). An intersection position between the light beam B incident on the screen and the S8 plane on the cross section is defined as R2 (second intersection position).

  Furthermore, the sign of curvature is defined as follows. That is, as shown in FIG. 20, when the light LT emitted from the light source device 1 travels toward the screen SC via the deflecting element 3, the light LT is present when the surface S made of a reflective surface or a refractive surface is present. Let the curvature of the surface S when it hits the surface S as a convex surface be a positive curvature, and the curvature of the surface S when the light LT hits the surface S as a concave surface be a negative curvature.

  The curvature can be uniquely obtained from the shape of the surface (that is, curvature = 1 / curvature radius). On the other hand, the power indicates the degree to which the traveling direction changes depending on the surface on which the light beam is incident, and is determined depending on the incident position and incident angle of the light beam in addition to the shape of the surface. In other words, the curvature can be obtained only from the shape of the surface, but the power cannot be obtained. In this regard, in this specification, the curvature and the power are distinguished from each other.

  As shown in FIGS. 11, 14, and 17, the S8 plane has a symmetrical shape with respect to a cross section (corresponding to the YZ plane) perpendicular to the screen SC including the screen center principal ray, and the intersection position R1 is The shape protrudes toward the light incident side. That is, the curvature in the second scanning direction (corresponding to the X direction) is positive in the cross section perpendicular to the first scanning direction (corresponding to the Y direction) at the intersection position R1 of the S8 surface. The surface shape in the cross section perpendicular to the first scanning direction passing through the intersection position R1 has a larger positive curvature than the surface shape in the cross section passing through the intersection position R2 and perpendicular to the first scanning direction. It has a shape.

  In the configuration in which the oblique projection is performed on the screen SC, the trapezoidal distortion in which the length of the lower side of the screen is shorter than the length of the upper side of the screen increases as the incident angle of the light beam on the screen SC increases. However, by setting the shape of the S8 surface as described above, a large negative power can be applied in the second scanning direction within the cross section passing through the intersection position R1 and perpendicular to the first scanning direction. . That is, in the S8 plane, a negative power can be given to the region through which the light ray A incident on the lower side of the screen passes. Therefore, it is possible to correct the trapezoidal distortion that occurs with oblique projection by widening the width in the second scanning direction at the bottom of the screen.

  At this time, when the trapezoidal distortion is corrected using a surface other than the S8 surface arranged closest to the screen SC, the effective area in the surface is enlarged on the surface on the screen SC side than the reflecting surface, and the optical system Increases in size. Therefore, it is desirable that the surface on which the trapezoidal distortion is corrected is the S8 surface that is the surface closest to the screen SC.

  If the trapezoidal distortion is suppressed, the light use efficiency can be improved and the projected image can be brightened. In other words, conventionally, only the rectangular area is displayed on the screen SC by turning off the laser light at the edge where the screen is distorted. However, the time during which the laser light is turned off can be reduced by suppressing the trapezoidal distortion. It can be used for original image display, and light utilization efficiency is improved. Further, if the image display area is the same as the conventional one, the scanning speed of one line can be reduced by using the time during which the laser light is turned off for the original image display. Thereby, a bright projection image can be obtained.

  Further, since the projection optical system 7 has a plurality of reflection surfaces (S5 surface, S8 surface), the optical path can be folded by these reflection surfaces, so that the projection optical system 7 is configured compactly. Can do. In each of the first to third embodiments, the optical path of the projection optical system 7 is folded by a plurality of reflecting surfaces in a cross section perpendicular to the screen SC including the screen center chief ray. The overall size is reduced. Furthermore, correction of trapezoidal distortion due to oblique projection requires a large negative power as described above, but by using a reflective surface, there is no chromatic aberration that would occur on a refracting surface of the same power, reducing chromatic aberration. Is possible.

  By the way, it is desirable to make the optical system as compact as possible in taking advantage of the features of the scanning projection apparatus. However, if the optical system is configured using only the reflecting surface, the optical system is separated for separation of the light beam and the surface. The volume increases. On the other hand, in a system with a large oblique projection angle, the difference in optical path length increases for each angle of view between the light beam B incident on the upper side of the screen and the light beam A incident on the lower side of the screen, resulting in field curvature. However, this field curvature can be corrected with a relatively weak surface.

  Therefore, by introducing the S6 surface which is a refracting surface into the projection optical system 7, while making the projection optical system 7 as compact as possible, the S6 surface is given a relatively weak power and the generation of chromatic aberration is reduced as much as possible. It becomes possible to correct curvature of field. The introduction of such a refracting surface is particularly effective for correcting field curvature that occurs in the second scanning direction.

  Here, FIG. 21 shows the distortion of the two-dimensional projection image in Example 1 as a distortion diagram. In FIG. 21, only the right half of the full screen shows distortion, but the full screen shows symmetrical distortion. FIG. 22 shows the distortion of the two-dimensional projection image in Example 2 as a distortion diagram, and FIG. 23 shows the distortion of the two-dimensional projection image in Example 3 as a distortion diagram.

  In each of Examples 1 to 3, the maximum scanning angle value (°) of the deflecting element 3, the mechanical scanning angle (°) used for projection, the maximum optical scanning angle (°), and the angle utilization efficiency (%) are as follows. As shown in Table 1. When the incident light is reflected and deflected by the deflecting element 3, the maximum optical scanning angle is physically twice the mechanical scanning angle. Further, as described above, the deflection element 3 is driven in a sine direction in the horizontal direction, but is projected on the screen SC for a certain period including a time point when the speed becomes zero (a time point when the deflection angle becomes maximum) when the reflecting surface is deflected. In order to prevent the image from becoming locally bright, the incidence of laser light on the deflection element 3 is turned off. Therefore, the angle utilization efficiency in the horizontal direction refers to the ratio of the time excluding the certain period to the time for scanning one line in the horizontal direction. On the other hand, the angle utilization efficiency in the vertical direction refers to the laser beam when moving to the next one-line scan with respect to the time from the start of one line scan in the horizontal direction to the start of the next one-line scan. The ratio of the time excluding the period for turning OFF.

Table 2 shows trapezoidal distortion and TV distortion in each of Examples 1 to 3. As shown in FIG. 24, the trapezoidal distortion is evaluated by taking the length of the straight line connecting the upper left corner of the screen and the upper right corner of the screen as L1 (mm), and the lower left corner of the screen and the lower right corner of the screen. When the length of the straight line connecting the corners is L2 (mm), the amount is calculated by the following equation.
Trapezoidal distortion (%) = {(L1-L2) / L2} × 100

On the other hand, the TV distortion is an aberration amount indicating the amount of curvature of the frame of the screen displayed on the screen SC. As shown in FIG. 25, the displacement amount (a, b) along the axis passing through the center of the screen. , C, d) divided by the screen width (A or B). In other words, the TV distortion on each side of the screen frame is
TV distortion upper side; a / A x 100 (%)
TV distortion bottom side; b / A x 100 (%)
TV distortion left side; c / B x 100 (%)
TV distortion right side; d / B x 100 (%)
Indicated by Note that the sign of TV distortion is positive in the direction in which each side moves away from the center of the screen, and negative in the direction toward (indents) the center of the screen.

  In the two-dimensional scanning system, non-rotationally symmetric distortion such as trapezoidal distortion accompanying oblique projection and field curvature occur on the screen. However, as in each of the first to third embodiments, the projection optical system 7 is configured using a plurality of reflecting surfaces (S8 surface, S5 surface) and a refracting surface (S6 surface), and the surface shape of the S8 surface is appropriate. It can be seen that by setting to, both the trapezoidal distortion and the curvature of field can be corrected well, and a good image can be formed over the entire screen. In addition, since the aberration to be corrected is shared between the reflecting surface and the refracting surface, it is possible to realize a scanning projection apparatus PJ having good performance with less chromatic aberration while reducing the size of the projection optical system 7. It becomes possible.

(5. Supplement on S8 surface)
In each of Examples 1 to 3, as shown in FIGS. 11, 14, and 17, the surface S <b> 8 has a continuous shape, and the light beam incident on the side on which the light beam A is incident (the lower side of the screen). In the region through which is passed, the entire region has a convex shape in the second scanning direction. Further, the surface S8 has a symmetrical shape with respect to a cross section perpendicular to the screen SC including the screen center principal ray. From this, it can be said that the S8 plane is symmetric with respect to the cross section (hereinafter, this cross section is also referred to as a symmetric plane) and has a region that is convex in the second scanning direction. At this time, in each of Examples 1 to 3, the region on the S8 surface satisfies the following conditional expression (1). That is,
| Φ1 / φ2 | <0.8 (1)
However,
φ1: curvature in the first scanning direction on the symmetry plane (1 / mm)
φ2: curvature in the second scanning direction on the symmetry plane (1 / mm)
It is.

  The above conditional expression defines conditions for obtaining a good screen shape when oblique projection is performed by the scanning optical system, and the upper limit value is a preferable value for obtaining a good screen aspect ratio. In the scanning optical system, the screen resolution is determined by the aperture diameter and the scanning angle of the deflecting member (deflecting element 3). When oblique projection is performed with the scanning optical system, the vertical size of the screen is enlarged in accordance with the oblique projection angle, but the horizontal size of the screen is not changed, so that a vertically long screen is obtained. By satisfying the conditional expression, the power in the second scanning direction becomes larger than the power in the first scanning direction, and the horizontal size of the screen can be expanded to obtain a screen with an appropriate aspect ratio. It becomes.

In particular, if the following conditional expression (2) is satisfied at the intersection position R1 of the S8 surface, it is desirable in that the above effect can be obtained with certainty. That is,
| Φ1 / φ2 | <0.2 (2)
It is.

Table 3 shows the curvature φ1 in the Y direction, the curvature φ2 in the X direction, and the absolute value | φ1 / φ2 | In Table 3, φ1 and φ2 are values at the intersections between the principal ray of the light beam and the S8 surface at each scanning angle of the MEMS mirror. Further, E−n = × 10 ⁻ⁿ is indicated. Here, when the horizontal scanning angle of the MEMS mirror is H (°) and the vertical scanning angle is V (°), in each of the first to third embodiments, when H = 0 °, the principal ray of the light beam Is incident on the symmetry plane of the S8 plane, and the intersection of the principal ray of the light beam and the S8 plane when H = 0 ° and V = 6.4 ° corresponds to the intersection position R1 described above. Further, the chief ray of the middle ray bundle among the five ray bundles reflected by the S8 surface in FIG. 2 corresponds to H = 0 ° and V = 0 °, and the chief ray of the second ray bundle from the top is the same. This corresponds to H = 0 ° and V = -3.2 °. From Table 3, it can be seen that each of Examples 1 to 3 satisfies the above conditional expressions (1) and (2).

  In each of the first to third embodiments, the absolute value of the curvature in the second scanning direction at the intersection position R1 between the S8 surface and the light beam A is the other reflecting surface (S5 surface) and refractive surface ( The surface shapes of the optical surfaces are set so as to be larger than the absolute values of the curvatures in the second scanning direction at the intersection positions P1 and Q1 between the surface S6 and the light ray A. With such a setting, the second scanning is performed at the intersection position R1 of the S8 surface arranged at the position closest to the screen SC among the intersection positions P1, Q1, and R1 through which the light ray A incident on the lower side of the screen passes. Since it has a strong negative power in the direction, it is possible to effectively correct the trapezoidal distortion of the lower side of the screen by expanding the lower side of the screen in the second scanning direction.

  Further, in each of the first to third embodiments, as described above, the S8 surface has a continuous shape, and in the region where the light beam incident on the side on which the light ray A is incident (the lower side of the screen) passes, The entire region has a convex shape in the second scanning direction. As a result, it is possible to correct the trapezoidal distortion by widening the width in the second scanning direction on the side where the light ray A is incident on the screen by oblique projection, and to obtain a screen shape with less distortion.

  In each of Examples 1 to 3, the S8 surface is a non-rotationally symmetric free-form surface. Thereby, the trapezoid distortion which is a non-rotationally symmetric aberration can be corrected by a small number of optical elements (for example, only the second reflection mirror 6 having the S8 surface).

  Further, the surface S8 has a symmetrical shape with respect to the cross section perpendicular to the screen SC including the screen center principal ray, and the light beam including the light ray A among the light beams incident on the upper side or the lower side of the screen intersects the S8 surface. In the region (the region passing through the intersection position R1 and along the second scanning direction), the absolute value of the curvature in the second scanning direction on the S8 surface increases as the distance from the symmetry surface in the second scanning direction increases. . That is, the S8 surface has a shape in which the inclination of the surface increases, that is, a shape in which the curvature increases in the positive direction as it goes from the intersection position R1 in the second scanning direction and away from the symmetry plane. It has become.

  With such a shape of the S8 surface, in the region of the S8 surface, the negative power increases as the distance from the symmetry surface in the second scanning direction increases. As a result, the width of the lower side of the screen in the second scanning direction is surely widened, and the focal length is changed in accordance with the change of the optical path length while effectively correcting the trapezoidal distortion accompanying the oblique projection. It is possible to bring the spot position closer to the vicinity of the screen SC.

  In each of the first to third embodiments, the region where the light beam including the light beam B and the S8 surface intersect among the light beams incident on the upper side or the lower side of the screen (the region passing through the intersection position R2 and along the second scanning direction). ), The curvature in the second scanning direction changes in the negative direction as the distance from the symmetry plane increases in the second scanning direction.

  When two-dimensional scanning is performed by the deflecting element 3, a pincushion-like scanning distortion occurs on the screen, and in the oblique projection configuration, the scanning distortion particularly occurs above the screen. Therefore, by setting the shape of the S8 surface as described above, the power in the second scanning direction can be changed in the positive direction as it moves away from the intersection position R2 in the second scanning direction. The negative power can be reduced by reducing the curvature), and the scanning distortion can be reduced by suppressing the spread of the upper edge of the screen.

  In the S8 plane, the surface shape of the cross section passing through the intersection position R2 and perpendicular to the first scanning direction may be convex or concave on the light incident side (at the intersection position R2, the first shape). 2 may have a negative curvature or may have a positive curvature). In short, on the S8 surface, the convex shape in the second scanning direction has only to become looser as it goes from the intersection position R1 to the intersection position R2 (the curvature in the cross section perpendicular to the first scanning direction is in the negative direction). Just change). If the surface shape of the S8 surface is set in this way, the first scan passes through the intersection position R1 and passes through the intersection position R1 rather than the power in the second scanning direction in the cross section perpendicular to the first scanning direction. Since the power in the second scanning direction in the cross section perpendicular to the direction can be increased to the negative side, the trapezoidal distortion described above can be reliably corrected.

(6. Supplement on S6 surface)
In each of the first to third embodiments, the S6 surface serving as the refracting surface is a non-rotationally symmetric free-form surface. This makes it possible to correct curvature of field on the S6 surface while correcting trapezoidal distortion, which is non-rotationally symmetric distortion occurring on the image plane.

  In Examples 1 and 2, the negative curvature increases and the negative power increases as the distance from the intersection position Q2 with the light beam B on the S6 plane increases in the second scanning direction. Along with the correction of the scanning distortion by the S8 surface, the spot position of the light beam incident on the edge of the upper side of the screen deviates from the screen SC. By setting the surface shape of the S6 surface as described above, the deviation of the spot position can be reduced. It can be corrected.

  On the other hand, in the third embodiment, as shown in FIG. 16, the curvature in the second scanning direction is positive in the cross section perpendicular to the first scanning direction at the intersection position Q2 between the surface S6 and the light beam B. 2 has a positive power in the scanning direction. As described above, in the two-dimensional scanning system, as the oblique projection angle increases (upward of the screen), the scanning distortion is more noticeable as described above. However, by setting the surface shape of the S6 surface as described above, Therefore, in addition to the trapezoidal distortion and the curvature of field, the scanning distortion can be further corrected on the surface S6.

  In each of Examples 1 to 3, the curvature in the second scanning direction is negative in the cross section perpendicular to the first scanning direction at the intersection point Q1 between the S6 surface and the light beam A. In this case, since the power in the second scanning direction is negative in the cross section, the lower portion of the screen can be expanded in the second scanning direction, and the trapezoidal distortion generated by the oblique projection can be effectively corrected. .

  In each of the first to third embodiments, the S6 surface is disposed between the reflective surface (S8 surface) disposed closest to the screen SC and the reflective surface (S8 surface) disposed closest to the deflection element 3 side. ing. In such an arrangement, the S6 surface is arranged closer to the deflecting element 3 than the reflecting surface (S8 surface) having the strongest negative power in the second scanning direction, so that the size of the optical system can be made compact. Good image performance can be obtained while maintaining.

(7. About S5 surface)
In the configuration in which the oblique projection is performed, the distance from the final surface (S8 surface) of the projection optical system 7 to the screen SC is shorter on the lower side of the screen than on the upper side of the screen. The spot position on the top is greatly deviated from the screen SC, and the spot is enlarged. As described above, the correction of the field curvature can be performed on the refracting surface (S6 surface). However, since the power on the refracting surface is weak, it is impossible to correct the field curvature or the chromatic aberration is corrected. It may be difficult to correct the curvature of field while reducing. On the other hand, in order to correct the trapezoidal distortion, the light ray incident on the lower side of the screen passes through the S8 surface having a strong negative power in the second scanning direction.

  Therefore, in each of the first to third embodiments, the second scanning is performed within the cross section perpendicular to the first scanning direction at the intersection position P1 between the surface S5 as the reflecting surface arranged closest to the deflecting element 3 and the light beam A. The surface shape of the S5 surface is set so that the curvature of the direction becomes negative. In particular, in the cross section including the central ray at the center of the screen, the curvature in the second scanning direction at the intersection position P1 is larger in the negative direction than the curvature in the second scanning direction at the intersection position P2. The surface shape is set.

  In such a setting, since positive power is applied in the second scanning direction at the intersection point P1 of the S5 plane, the focal distance in the vicinity of the principal ray of the light incident on the lower side of the screen is set to the light incident on the upper side of the screen. Can be made shorter than the focal length in the vicinity of the principal ray. Thereby, it is possible to correct the curvature of field that cannot be corrected on the S6 surface while correcting the trapezoidal distortion on the S8 surface, using the S5 surface. In addition, on the cross section including the central ray at the center of the screen, the spot position at the angle of view where the incident angle with respect to the screen is the smallest (spot position of the light ray A) is in the vicinity of the screen SC. Can be prevented.

  In this way, by properly balancing the positive power at the intersection position P1 of the S5 plane and the negative power at the intersection position R1 of the S8 plane, both the correction of the curvature of field and the correction of the trapezoidal distortion are ensured. It is possible. Also, by making the power at the intersection position P1 of the S5 surface, which is the reflecting surface closest to the deflecting element 3, positive, the effective area of the surface on the screen SC side is not enlarged compared to the S5 surface, so the projection optical system 7 is compact. Can be configured.

  Further, as described above, the deflection element 3 is sine-driven at a high speed in the horizontal direction. In the case of such a sine drive, the horizontal scanning speed is higher at the center than at the horizontal end. For this reason, the locus of the spot corresponding to one pixel becomes longer in the horizontal direction at the center and shorter at the end.

  In order to correct the size of the spot trajectory corresponding to one pixel due to such a difference in scanning speed, it is necessary to adjust the spot size in accordance with the scanning speed. That is, by reducing the spot size in the horizontal direction at the center and increasing the spot size in the horizontal direction at the end, the size of the locus of the spot corresponding to one pixel due to the difference in scanning speed is It can be made equal within one horizontal line.

  By setting the surface shape of the S5 surface as described above, the spot size at the center of the lower side of the screen can be reduced. Therefore, for example, with respect to the light ray incident on the center of the lower side of the screen, the correction of the curvature of field is emphasized to reduce the spot size, and the correction of the trapezoidal distortion is emphasized with respect to the light ray incident on the end of the lower side of the screen. As described above, it is also possible to vary the aberration for which correction is important according to the position in one scanning line. As a result, it is possible to project a good image on the screen SC by performing a well-balanced correction of the curvature of field, the correction of trapezoidal distortion, and the correction of the spot shape due to the difference in scanning speed.

  In the above description, the scanning surface projected by the scanning projection device PJ is the screen SC, but the scanning surface may be a wall. Further, a projection-type image display device may be configured using the scanning projection device PJ and the screen SC.

  The scanning projection apparatus of the present invention can be used for pocket projectors, data projectors, rear projection televisions, and the like.

Claims (13)

Light source means;
A deflecting member for deflecting light emitted from the light source means in a first scanning direction and a second scanning direction orthogonal to each other;
A projection optical system that guides light deflected by the deflecting member to a surface to be scanned, and that scans the surface to be scanned two-dimensionally with the light,
The first scanning direction coincides with the screen short side direction of the surface to be scanned,
The projection optical system has a plurality of reflecting surfaces and a refracting surface,
Of the light rays incident on the upper and lower ends of the screen on the cross section perpendicular to the surface to be scanned including the screen main chief ray, the light ray having a smaller incident angle with respect to the screen is defined as the first light beam, and the light beam having the larger incident angle with respect to the screen is designated as the first light ray. 2, the curvature in the second scanning direction at the first intersection position between the reflection surface arranged closest to the scanned surface among the plurality of reflection surfaces and the first light beam is positive. A scanning projection apparatus characterized by having a positive curvature larger than a curvature in a second scanning direction at a second intersection position between the reflecting surface and the second light beam. The reflective surface arranged on the most scanned surface side is symmetrical with respect to a cross section perpendicular to the scanned surface including the screen center principal ray, has a convex shape with respect to the second scanning direction, and The scanning projection apparatus according to claim 1, wherein the scanning projection apparatus has a region that satisfies the following conditional expression (1):
| Φ1 / φ2 | <0.8 (1)
However,
φ1: curvature in the first scanning direction on the symmetry plane
φ2: curvature in the second scanning direction on the symmetry plane. The scanning projection apparatus according to claim 2, wherein the following conditional expression (2) is satisfied at the first intersection point position;
| Φ1 / φ2 | <0.2 (2)
It is.   Of the plurality of reflecting surfaces, the curvature in the second scanning direction at the intersection of the reflecting surface arranged closest to the deflecting member and the first light beam is negative and is arranged closest to the deflecting member. 4. The scanning projection apparatus according to claim 1, wherein a curvature in a negative direction is larger than a curvature in a second scanning direction at an intersection position between the reflecting surface and the second light beam. 5.   The absolute value of the curvature in the second scanning direction at the position of the first intersection between the reflecting surface arranged closest to the surface to be scanned and the first light beam is the other reflecting surface and refractive surface of the projection optical system. 5. The scanning projection apparatus according to claim 1, wherein an absolute value of a curvature in a second scanning direction at each intersection position with the first light ray is larger than each of the absolute values. The reflecting surface arranged on the most scanned surface side is a non-rotationally symmetric surface and has a symmetrical shape with respect to a cross section perpendicular to the scanned surface including the screen center principal ray,
In the region where the light beam including the first light beam and the reflection surface intersect, the absolute value of the curvature of the reflection surface in the second scanning direction increases as the distance from the symmetry surface in the second scanning direction increases. A scanning projection apparatus according to any one of claims 1 to 5.   The scanning according to any one of claims 1 to 6, wherein the optical path of the projection optical system is folded by a plurality of reflecting surfaces in a cross section perpendicular to the surface to be scanned including the screen center principal ray. Mold projection device.   The scanning projection apparatus according to claim 1, wherein the refractive surface is a non-rotationally symmetric free-form surface.   9. The scanning projection apparatus according to claim 1, wherein a curvature in the second scanning direction is negative at an intersection position between the refractive surface and the first light beam.   10. The refracting surface is disposed between a reflecting surface disposed closest to the surface to be scanned and a reflecting surface disposed closest to the deflecting member. Scanning projector.   In the region where the light beam including the second light beam and the reflection surface arranged closest to the surface to be scanned intersect, the curvature of the reflection surface in the second scanning direction as the distance from the symmetry surface in the second scanning direction increases. The scanning projection apparatus according to claim 6, wherein the angle changes in a negative direction. An optical member that guides the light emitted from the light source means to the deflecting member;
The scanning projection apparatus according to claim 1, wherein the optical member has a positive power.   The scanning projection apparatus according to claim 12, wherein the optical member has anamorphic power.

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