JP2011232566A - Optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a projection image having high resolution which is put in focus on the entire surface by suppressing distortion in an optical system in which an image having an angle of about 180 degrees is projected to a cylindrical screen.SOLUTION: The optical system includes: a projection optical system 14 which projects the displayed image to an image display element 13; and a cylindrical reflective surface 12 which reflects the image projected by the projection optical system 14 and projects the image having the angle of about 180 degrees to a cylindrical screen 11. The projection optical system 14 includes a correction optical system L2 which corrects astigmatism generated on the cylindrical reflective surface 12.

Description

  The present invention relates to an optical system including a projection optical system, and more particularly to an optical system capable of projecting a high-resolution image without image distortion on a cylindrical projection surface (screen). is there.

  Regarding a projection optical system that projects a real image onto a cylindrical screen using a projection optical system, Patent Document 1 discloses a small-sized flare light in an optical system that projects an image having an angle of view of 360 ° in all directions. It is disclosed to provide an optical system having a small resolution and good resolution.

JP 2007-334019 A

  According to the optical system described in Patent Document 1, by projecting an image around the entire periphery, the observer can observe the image spreading in a panoramic shape around the entire periphery, thereby immersing the observer in the image. Become. However, in order to project such a 360 ° image, it is necessary to provide a certain amount of space around the optical system.

  Therefore, with the optical system described in Patent Document 1, it is difficult to enjoy an immersive image in a limited space such as in an airplane. Here, in the situation where the observer is seated on a chair, sofa, etc., it is not necessary to project an image up to 360 °, and it is understood that an immersive feeling can be obtained even with a projected image close to 180 °. Yes. This is because the viewpoint range of the observer is limited by sitting.

  The present invention is capable of projecting a high-resolution projection image in which the entire surface is in focus while suppressing distortion in an optical system that projects an image of approximately 180 ° onto such a cylindrical projection surface (cylindrical screen). It aims at providing the optical system characterized by this.

  An optical system according to the present invention is a projection optical system that projects an image displayed on an image display element, and a cylindrical that reflects an image projected by the projection optical system and projects an image close to 180 ° on a cylindrical screen. An optical system including a cylindrical reflecting surface, wherein the projection optical system includes a correction optical system that corrects astigmatism generated on the cylindrical reflecting surface.

  Furthermore, in the optical system according to the present invention, the correction optical system is a cylindrical lens.

  As described above, according to the present invention, there is provided a projection optical system capable of projecting a high-resolution image on a cylindrical projection surface (cylindrical screen) without image distortion with a simple configuration. It becomes possible to do.

It is the figure which showed the cross section in the YZ plane about the optical system which concerns on embodiment of this invention, and its periphery structure. It is the figure which showed the cross section in ZX plane about the optical system which concerns on embodiment of this invention, and its periphery structure. It is the figure which showed the mode of observation by the cross section in a YZ plane, and the observer about the optical system which concerns on embodiment of this invention, and its periphery structure.

  The optical system of the present invention will be described below based on examples. FIG. 1 is a view showing a cross section in the YZ plane of an optical system according to an embodiment of the present invention and its peripheral configuration. FIG. 2 is a view showing a cross section in the ZX plane in FIG.

  The entire apparatus in this embodiment includes a projector 10, a cylindrical mirror 12 (cylindrical reflection surface), and a cylindrical screen 11. The image projected from the projector 10 is reflected by a cylindrical mirror 12 having a curvature on the ZX plane as shown in FIG. 2, and is projected on a cylindrical screen 11 having a curvature on the ZX plane.

The cylindrical mirror 12 is a reflecting surface having a center of the cylindrical center SO and a curvature in the ZX plane. The radius of curvature R [mm] of the cylindrical mirror 12 is
200 <R <400
It is preferable that If the lower limit is exceeded, astigmatism generated on the surface of the cylindrical mirror 12 becomes large, and correction cannot be performed by the correction optical system L2 formed of a cylindrical lens. Further, if the upper limit is exceeded, the effective diameter of the cylindrical mirror 12 is increased, and the observation position is significantly restricted at the same time as the apparatus becomes large.

  Similar to the cylindrical mirror, the cylindrical screen 11 is a reflecting surface having a center of the cylindrical center SO and a curvature in the ZX plane. The central axis A1 of the cylindrical screen 11 is arranged so as to be decentered in the Y-axis direction with respect to the central axis A2 of the projection optical system 14 in the projector 10, and is projected obliquely from the projector 10 onto the cylindrical mirror 12. An image can be projected onto the cylindrical screen 11. The projected image of the projector 10 reflected by the cylindrical mirror 12 becomes a projected image on the cylindrical screen 11 and is observed by an observer.

  FIG. 1 also shows an enlarged view of a portion (projector 10) surrounded by a broken line. The projector 10 includes an image display element 13 for displaying an image such as an LCD, an ideal lens L1, and a correction optical system L2. A stop surface indicated by r5 is provided between the ideal lens L1 and the correction optical system L2. In the present embodiment, the projection optical system 14 is formed by the ideal lens L1 and the correction optical system L2.

  As shown in the figure, the central axis A2 of the projection optical system 14 is arranged eccentrically with respect to the central axis A3 of the video display element 13. Therefore, the image irradiated from the image display element 13 is projected using the periphery of the ideal lens L1, and is projected obliquely to the cylindrical mirror 12 arranged eccentrically, just like using the shift lens. .

  Thus, it is preferable that the image display element 13 is shifted eccentrically and oblique projection is performed, since there is no distortion. Note that trapezoidal image distortion occurs when the projection optical system 14 is tilted, but such image distortion can be corrected electronically.

In the present embodiment, the cylindrical mirror 12 (cylindrical reflection surface) is used as means for enlarging the projection angle of view in the horizontal direction. However, the use of the cylindrical mirror 12 causes astigmatism, which degrades the image formed on the cylindrical screen. Therefore, in the present embodiment, this astigmatism is corrected by using the correction optical system L2 including a cylindrical lens.

  In the present embodiment, the projection optical system 14 is designed using the ideal lens L1. Ray tracing is performed by tracing back rays from the surface of the cylindrical screen 11 toward the image display element 13. The coordinate origin O is the center of the cylindrical screen, and on the paper surface of FIG. 1, the front side of the paper surface is the X-axis positive direction, the upward direction is the Y-axis positive direction, and the right direction is the Z-axis positive direction.

  A numerical example will be shown below. The coefficient term for which no data is described is zero. The refractive index and Abbe number are for d-line (wavelength 587.56 nm). In addition, the unit of length which is not indicated in particular is mm.

  For the eccentric surface, the amount of eccentricity from the cylindrical center SO (X-axis direction, Y-axis direction and Z-axis direction are X, Y and Z, respectively) excluding the screen surface and the coordinate system defined by the origin of the optical system Tilt angles (α, β, γ (°), respectively) of a coordinate system that defines each surface centered on the X axis, the Y axis, and the Z axis are given. Note that positive α and β mean counterclockwise rotation with respect to the positive direction of each axis, and positive γ means counterclockwise rotation with respect to the positive direction of the Z axis.

The cylindrical screen 11 is the inside of a cylindrical surface with a radius of 1 m having the cylindrical screen center SO at the center position. The focal length of the ideal lens L1 of the projector 10 is 50 mm, and the image height is 13.47 × 22.58.

[Numerical example]
Surface number Curvature radius Surface spacing Eccentric Refractive index Abbe number
r1 (object surface) Cylindrical surface [1] 700.00
r2 Cylindrical surface [2] -300.00 Eccentricity [1]
r3 Cylindrical surface [3] -5.00 Eccentricity [2] 1.5163 64.1
r4 ∞ -10.00 Eccentricity [3]
r5 (diaphragm surface) -50.00 eccentricity [4]
r6 ∞ -46.60 Eccentric [5]
r7 (image plane) ∞ Eccentricity [6]

Cylindrical surface [1]
X direction radius of curvature 1000.00
Y direction radius of curvature ∞

Cylindrical surface [2]
X direction radius of curvature 300.00
Y direction radius of curvature ∞

Cylindrical surface [3]
X direction radius of curvature -570.73
Y direction radius of curvature ∞

Eccentric [1]
X 0.00 Y 345.48 Z -300.00
α 0.00 β 0.00 γ 0.00

Eccentric [2]
X 0.00 Y 500.00 Z -600.00
α 0.00 β 0.00 γ 0.00

Eccentric [3]
X 0.00 Y 500.00 Z -605.00
α 0.00 β 0.00 γ 0.00

Eccentric [4]
X 0.00 Y 500.00 Z -615.00
α 0.00 β 0.00 γ 0.00

Eccentric [5]
X 0.00 Y 500.00 Z -665.00
α 0.00 β 0.00 γ 0.00

Eccentric [6]
X 0.00 Y 526.70 Z -718.40
α 0.00 β 0.00 γ 0.00

FIG. 3 is a diagram showing a cross section in the YZ plane and a state of observation by an observer for the optical system according to the embodiment of the present invention and its peripheral configuration. The configuration and light rays are the same as in FIG. In the apparatus of the present embodiment, the observer is observed in a situation where the observer is seated as illustrated, for example. For observation, it is preferable that the line-of-sight direction of the observer is in the sitting state along the Z axis. Therefore, by making the projector 10 and the cylindrical mirror 12 movable so that the position can be changed according to the seating state, it is possible to provide a projection image that can be easily observed according to the seating situation. Moreover, in a reclining-type movable seat or the like, the entire apparatus may be tilted according to the reclining angle.

  Thus, according to the apparatus using the optical system of the present embodiment, it is possible to provide an immersive projection image in a state where an observer is seated. Furthermore, it is possible to project a high-resolution projection image on the cylindrical screen 11 with distortion suppressed and focused on the entire surface.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention. Is.

DESCRIPTION OF SYMBOLS 10 ... Projector, 11 ... Cylindrical screen, 12 ... Cylindrical mirror (cylindrical reflective surface), 13 ... Image display element, L1 ... Ideal lens, L2 ... Correction optical system, SO ... Cylindrical center

Claims (2)

A projection optical system that projects the image displayed on the image display element;
A cylindrical cylindrical reflecting surface that reflects an image projected by the projection optical system and projects an image close to 180 ° on a cylindrical screen, and an optical system comprising:
The projection optical system includes a correction optical system that corrects astigmatism generated on the cylindrical reflecting surface. The optical system according to claim 1, wherein the correction optical system is a cylindrical lens.