JP2005274936A - Projector, game machine, and image projection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain superior images by using a Fresnel lens, having a focal length larger than the actual projection distance in a small/thin apparatus, such as a rear projection pachinko machine. <P>SOLUTION: In a rear projector having a Fresnel lens on its screen, it becomes possible to utilize the light of the screen center most efficiently and to suppress the luminance uneven at the upper and lower sections of the screen by using a Fresnel lens of a focal length larger than the actual projector distance, and offsetting the optical axis of the projection optical system and the optical axis of the Fresnel lens. Further, it becomes possible to reduce the luminance differences in the lateral directions by changing the shape of the Fresnel lens. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projector preferably incorporated in a gaming machine or the like, a gaming machine using such a projector, and an image projection method.

A small and thin gaming machine such as a rear projector pachinko machine needs to perform a wide-angle projection with a short focus, but in reality, it is difficult to design a lens having a focal length within a range that can be accommodated in the gaming machine. In general projectors, in order to reduce the thickness, countermeasures such as adding a tilt due to an optical shift or performing trapezoid correction by image correction after oblique projection are performed (for example, see Patent Document 1).
JP-A-10-319501

  However, in this case, since the incident angle of the image light with respect to the Fresnel lens arranged behind the screen and adjusting the emission angle of the image light is extremely large at the upper end position, a Fresnel lens that refracts the emitted light to be parallel is used. Even when the refractive power of the Fresnel lens cannot be made, the light emitted from the Fresnel lens becomes radial.

  In this way, when the light emitted from the screen is radial, when viewing the screen at a short distance like a pachinko machine, the image light is directed toward the player's eyes on the lower side of the screen due to the difference in the angle of the emitted light. The brightness is high because it goes, but the brightness is low because the image light deviates upward on the upper side of the screen. Further, since the projection is performed obliquely, the projection distance on the lower end side is shorter than the upper end side, and the density difference of the light flux is structurally generated and the upper end side becomes dark.

  Therefore, an object of the present invention is to provide a projector that can form an image with a good image quality with little luminance unevenness of projection light. It is another object of the present invention to provide a gaming machine having a display with less luminance unevenness and an image projection method that is preferably used in the gaming machine.

  In order to solve the problems of the present invention, a first projector according to the present invention includes a rear projection type projection apparatus main body that projects a projected image from the rear by a projection optical system, and projection light projected from the projection apparatus main body. An optical path correction optical system that corrects the optical path of the projection apparatus, and a screen that displays, as the projection image, light projected by the projection apparatus main body that has been optical path corrected by the optical path correction optical system, the projection apparatus main body includes the projection optical system Are arranged so as to be separated from the optical axis of the optical path correction optical system, and the central optical path through which the central portion of the light beam of the projection light from the projection apparatus main body passes is the optical path correction The optical system is arranged along a predetermined focal path of the optical system. Here, the focus optical path refers to an optical path passing through the focal point of the optical path correction optical system.

  In this case, when the projection apparatus main body is offset with respect to the optical axis of the optical path correction optical system, the center optical path of the projection light can be brought on the focal optical path of the optical path correction optical system. That is, the optical path direction of the projection light can be adjusted while adapting the center optical path of the projection light to the optical path correction optical system. For example, the principal point of the projection optical system in the projection apparatus main body is shifted on the focal light path. Since the principal point is on the center of the optical path of the projection light, the direction of the central optical path can be adjusted to the focal light path. By this adjustment, the central optical path of the projection light becomes substantially parallel to the normal of the screen after passing through the optical path correction optical system.

  As a specific aspect of the projector, a focal length of the optical path correction optical system is longer than a projection distance of the projection light. In this case, since the projection apparatus main body can be installed in front of the focal position of the optical path correction optical system, the projection apparatus main body can be brought closer to the optical path correction optical system, and the projector can be miniaturized.

  As another specific aspect of the projector, the central optical path of the projection apparatus main body is on a line extending in the reverse direction through the optical path correction optical system, the optical path passing through the center of the screen vertically. is there. In this case, the viewpoint can be arranged at the center of the screen, and an image with less luminance unevenness can be provided to the person facing the center of the screen.

  As a more specific aspect of the projector, the optical path correction optical system is a Fresnel lens that adjusts an emission angle of projection light emitted from the screen. In this case, by using a Fresnel lens, the optical path of the projection light is corrected, and the lens can be made thinner as compared to using a normal lens as the optical path correction optical system.

  As another specific aspect of the projector, the optical axis of the Fresnel lens coincides with a parallel line obtained by shifting a perpendicular passing through the center of the screen downward by a predetermined distance. In this case, the projection apparatus main body can be shifted to a position shifted downward from the Fresnel lens focal point.

  Further, as another specific aspect of the projector, the optical path correction optical system may include at least a vertical peripheral optical path of the projection light from the projection apparatus main body around the central optical path with respect to the normal of the screen. Parallelize. In this case, the image light around the center image has a uniform exit angle and luminous flux density in the vertical direction, so that the projected image is of high quality with little luminance unevenness.

  As another specific aspect of the projector, the optical path correction optical system further parallelizes the peripheral optical path in the lateral direction around the central optical path with respect to the normal of the screen. In this case, the image light around the central image has a uniform emission angle and luminous flux density in the horizontal direction, so that the projected image is of a high quality with less luminance unevenness.

  In order to solve the problems of the present invention, the second projector is obtained by changing the curvature of the annular zone of the Fresnel lens, and a rear projection type projection apparatus main body that projects a projected image from the rear by a projection optical system. The optical path correction optics of the Fresnel lens type that makes the peripheral optical path in the lateral direction relatively parallel to the central optical path out of the central optical path through which the central portion of the luminous flux of the projection light from the projection apparatus body passes. And a screen for displaying, as the projection image, light projected by the projection apparatus main body whose optical path has been corrected by the optical path correction optical system.

  When performing image projection by rear projection, for example, a Fresnel lens is usually used to obtain parallel light. However, in order to reduce the size of the projector, the optical axis of the oblique projection or projection optical system is used as the optical axis of the lens. There are cases in which a projection method such as projection offset from the projection is forced. In this case, depending on the normal Fresnel lens as described above, parallel light may not be obtained in the lateral direction of the projection light. In particular, when the periphery of the Fresnel lens is used, the projection light may diverge in the lateral direction. On the other hand, in the present invention, by changing the curvature of the annular zone of the Fresnel lens, it is possible to correct the lateral direction of the optical path of the projection light, and the projection light diverges when it is emitted to the screen. Can be prevented.

  As a more specific aspect relating to the optical path correction optical system of the projector, the optical path correction optical system includes a symmetrical axis in which an off-axis optical section of a ring zone of the Fresnel lens is spaced in parallel by a predetermined distance from the optical axis of the Fresnel lens. It has a shape rotated around.

  When a part of a normal Fresnel lens is used as it is as the optical path correction optical system, especially when a part of the Fresnel lens used is the peripheral part of the lens, the divergence of the projected light becomes remarkable in the left-right direction, and the projected image May cause uneven brightness. However, in this case, since a new curvature is given to the annular zone of the Fresnel lens, the optical path of the projection light can be corrected in the left-right direction.

  As another specific aspect of the first and second projectors, the projection apparatus main body further includes an optical path direction changing member that bends the optical path of the projection light between the projector and the screen. In this case, since the direction of the projection light can be controlled by the optical path direction conversion member, the projector can be further downsized.

  The above-described device can be incorporated into a gaming machine having a projection image display function such as a pachinko machine. As an aspect of the gaming machine using the projector described above, the gaming machine includes any one of the projectors described above and a gaming board provided with the screen of the projector, and the projector displays an image related to the game on the screen. Project. In this case, the image displayed on the screen has a good image quality with little luminance unevenness as a whole because the projection light around the center of the screen is parallel to the perpendicular of the game board surface.

  When performing image projection, it is necessary to reduce the size and thickness of the projector while maintaining good image quality by various methods. In order to reduce the size and thickness of the projector by adjusting the optical path when performing projection, the image projection method according to the present invention uses the projection light for displaying the projection image by the image projection means from the back side of the screen. A step of projecting, and a step of correcting the optical path of the projection light by an optical path correction optical system before incidence of the screen, and when performing optical path correction by the optical path correction optical system, the central optical path of the projection light is the above The position of the image projection means for the projection light is shifted so that it passes through the center of the screen vertically.

  In order to reduce the size of the projector, it is necessary to perform projection at a projection distance shorter than the focal length of the optical path correction optical system. Thus, when the light source point of the projection light is brought to the near side from the normal focus position, it is impossible to make the projection light parallel, but in the method according to the present invention, the position of the image projection means of the projection light Therefore, the center optical path of the projection light can be made parallel to the normal of the screen, and the surrounding light is also made substantially parallel to project a good image quality with little luminance unevenness. Is possible.

[First Embodiment]
FIG. 1 is a front view of a pachinko gaming machine including a rear projector, which is a first embodiment of a gaming machine according to the present invention. This pachinko gaming machine is installed in the front of the front image of the gaming machine main body 1 that houses the internal operation mechanism for supplying, collecting, and passing the pachinko balls, and allows the player to visually recognize the design of the pachinko machine. Necessary for various games such as the see-through plate 10, the handle 31 for adjusting the ball injection, the ball receiver 32 for receiving the ball, the surplus ball receiver 33 for receiving the extra ball, the screen 8 for displaying the image. A game board 9 is provided that has a surface projection structure such as a winning opening 34 or a nail 35 to form a game symbol.

  FIG. 2 is a side sectional view for explaining the internal structure of the pachinko gaming machine. This gaming machine includes a gaming machine main body (not shown) 1, a projector mechanism 2 for creating an image, and an image forming unit 6 for displaying various symbols including images created by the projector mechanism 2.

  The projector mechanism 2 is a projection device main body that projects an image, and includes a projector main body 3 including a projection lens OL that is a projection optical system, and an optical path direction conversion member that reflects the projection light PL from the projector main body 3 in the image display direction. And a Fresnel lens 5 which is an optical path correction optical system for collimating the reflected projection light PL.

  The image forming unit 6 includes a screen 8 that projects an image by the projection light PL and diverges at an appropriate angle, and a surface protrusion structure such as a winning opening 34 or a nail 35, thereby forming a game board 9 that forms a game pattern. And a see-through board 10 that is positioned in front of the game board 9 and that allows the player to visually recognize the game board surface.

  The projection light PL projected from the projector main body 3 is reflected by the reflection mirror 4 installed on the back side of the game board and is directed to the front image display direction. In this case, the gaming machine main body 1 can be thinned by using the reflection mirror 4. The reflected projection light PL is collimated through the Fresnel lens 5 and irradiates the game board 9 from the back through the screen 8. The projection light PL that has passed through the game board 9 is diverged at an appropriate angle defined by the screen 8. The player can grasp the surface pattern of the game board 9, the image of the surface protrusion structure, and the like through the see-through board 10 as a pattern.

  The optical system apparatus described above has an optical system structure similar to that of a general rear projector type game machine. In this case, the projector mechanism 2 projects the projection light PL obliquely onto the screen 8 and the reflection mirror 4 bends the optical path to reduce the thickness. However, this is not sufficient. Therefore, in the present embodiment, the principal point of the projection lens OL that normally exists on the optical axis of the Fresnel lens 5, that is, the position of the exit pupil is shifted from the optical axis, and further closer to the Fresnel lens 5 side. Thinner.

  FIG. 3 is a diagram showing an optical path of the projection light PL for explaining the feature in the present embodiment. For simplicity, the reflecting mirror 4 is omitted and the optical path is not bent. In actual use, as will be described later, when the thickness can be sufficiently reduced only by the present invention, the reflection mirror 4 does not have to be used. If necessary, the reflection mirror 4 can be further reduced in thickness. You may plan.

  The optical axis of the Fresnel lens 5 is OA, the principal point is S, and the focal point is F. In this case, the principal point S and the focal point F are both on the optical axis OA. The distance SF is the focal length of the Fresnel lens 5. This is represented by f. A focal optical path that is an optical path from the focal position to the Fresnel lens 5 is indicated by a broken line and is denoted as OA, OB, and OC. That is, the optical axis OA is one of the focal light paths. On the other hand, the observation point of the player is E. Among the focal light paths, those passing through the observation point E are broken lines OB. Let R be the principal point of the projection lens OL that is built in the projector body 3 and projects the projection light PL. The projection light PL projected around the principal point R is represented by a solid line. Of the luminous flux of the projection light PL, the light passing through the center is defined as the central optical path, and is represented by CP. Therefore, the principal point R is on the central optical path CP. The optical paths of the peripheral light around the central optical path CP are AP and BP.

  When the projection light PL is projected perpendicularly to the screen 8 from the focal point F, after passing through the Fresnel lens 5, the projection light PL becomes parallel light. However, when the light source point of the projection light PL is brought closer to the focal point F with respect to the Fresnel lens 5 on the optical axis OA, the projection light PL cannot become parallel light after passing through the Fresnel lens. Therefore, in this embodiment, by bringing the position of the principal point R to a position off the optical axis OA, the central optical path passing through the player's observation point E corresponding to the center of the screen by the screen 8 of the gaming machine. By making the image light on the CP parallel to the perpendicular of the screen 8 and making the peripheral image light parallel to the central optical path CP, the luminous flux of the image light from the entire screen 8 is made uniform. To solve.

  As described above, the broken line OB that is the focal light path becomes parallel to the optical axis OA after passing through the Fresnel lens 5. Therefore, first, the position of the principal point R is shifted on the broken line OB. Furthermore, the direction of the central optical path CP of the projection light PL emitted around the principal point R is matched with the direction of the broken line OB. Thereby, the central optical path CP becomes parallel to the optical axis OA after passing through the Fresnel lens 5. That is, the central optical path CP is perpendicular to the screen 8. At this time, the peripheral light paths AP and BP are also more perpendicular to the screen 8 than in the case of the conventional oblique projection, for example, and the light flux is made uniform. (Details will be described later.) As a result, at the observation point E, which is the player's viewpoint, and the periphery thereof, the image is formed with a high quality image with uniform image light and less unevenness of brightness. It can be recognized as a game screen.

  If the projection light PL is sufficiently wide, the position of the principal point R can be brought closer to the Fresnel lens 5, and the distance d between the principal point R and the Fresnel lens 5 becomes shorter than the focal length f, and the projector Sufficient miniaturization can be achieved. Thereby, thickness reduction of the game machine main-body parts 1, such as a pachinko machine, is attained.

  Hereinafter, in order to explain the optical function of this embodiment, a conventional structure to be compared will be described. FIG. 4A is a side sectional view for explaining an optical structure of a general rear projector. Since the projection method is the same as that in FIG. Similarly to FIG. 3, the optical axis of the Fresnel lens 5 is OA, the principal point is S, the focal point is F, and the focal length SF is represented by f. When the reflection mirror 4 is not used, the projector main body 3 ′ (illustrated by a dotted line in the figure) that is a generation source of the projection light PL must be installed in the vicinity of the focal point F. Therefore, the size of the projector mechanism is surely reduced by using the reflection mirror 4. However, for example, in order to perform projection of a sufficiently large size on the entire screen 8 in a normal pachinko gaming machine, the focal length f has a minimum design limit of about 360 mm. On the other hand, in the rear projector type pachinko machine, the distance from the screen to the back of the main body needs to be within about 200 mm. With this thickness, it is not sufficient to have a short focal point and a wide angle, and to arrange the screen 8 and the reflection mirror 4 at an acute angle, and it is necessary to reduce the thickness by oblique projection or the like.

  FIG. 4B is a side sectional view for explaining the optical structure of a rear projector type pachinko gaming machine using oblique projection conventionally used. The meanings of the respective symbols having the same names as those in FIG. 3 are the same as those in FIG. In order to simplify the comparison, the case where the reflection mirror 4 is not used will be illustrated. A point R ′ indicates the principal point of the projection lens OL, and the principal point R ′ is on the optical axis OA of the Fresnel lens 5 and is located on the front side with respect to the Fresnel lens 5 compared to the focal point F. Let e be the distance from the principal point S to the principal point R ′. In actual use, the angle between the reflection mirror 4 and the screen 8 can be made more acute by projecting the projection light PL obliquely upward. Thereby, it is possible to reduce the thickness of the projector that can be used in the rear projector type pachinko gaming machine. However, in this case, since the direction of all the projection optical paths including the central optical path CP is obliquely upward, the difference in the optical path direction due to refraction after passing through the Fresnel lens 5 is further increased, and the light amount on the solid line AP side is dense. On the other hand, the amount of light on the solid line BP side is sparse. That is, as described above, the upper end side becomes darker than the lower end side on the screen. Further, it is necessary to perform image correction accordingly. Further, when the inclination angle of the central optical path CP becomes large, the projection light PL cannot be refracted by the Fresnel lens 5.

  FIG. 4C is a side sectional view showing again the optical structure of the rear projector type pachinko gaming machine according to the present embodiment described in FIG. 3 for comparison. Since each symbol is the same as in FIG. 3, the description thereof is omitted. As described above, the principal point R is on the optical path of the broken line OB, and the observation point E can be on the central optical path CP of the projection light PL by matching the direction of the central optical path CP with the broken line OB. Further, at this time, the central optical path CP is horizontal. In this case, since the projection light PL originally spreads radially around the central optical path CP, the optical paths AP and BP, which are peripheral optical paths, are also substantially parallelized. Therefore, the difference between the light amount on the AP side and the light amount on the BP side is smaller than that in FIG. 4B, and the light amount in the vicinity of the center of the screen of the gaming machine is balanced, so that a high-quality image can be obtained.

  Further, as can be seen from the one-point difference line in the figure, if the distance d from the Fresnel lens 5 to the principal point R is shorter than the distance e from the Fresnel lens 5 to the original principal point R ′, the projector is used without using the reflection mirror 4. It is possible to reduce the thickness of the mechanism. In addition, it is also possible to use the reflection mirror 4 similarly to the prior art.

  Although the present embodiment has been described above, the present invention is not only related to pachinko gaming machines, but to other gaming machines such as slot machines and other devices that incorporate all rear projection projectors for observation at close distances. Is also applicable.

[Second Embodiment]
In the first embodiment, the problem is solved mainly by considering the principal point and the projection direction. However, in this embodiment, the Fresnel lens 5 (see FIG. 3) which is an optical path correction optical system is further considered. And Except for the Fresnel lens 5, the projector of this embodiment is the same as that of the first embodiment.

  In the first embodiment, the Fresnel lens 5 has no problem in normal use. However, the projection light PL diverges in the left-right direction of the image plane, particularly when the peripheral part of the entire Fresnel lens that is greatly deviated from the optical axis is used as the Fresnel lens 5, and the image quality of the projected image is reduced. The problem of falling may occur.

  FIG. 5 is a diagram for explaining the problem in the present embodiment and a method for solving the problem, and a front view of the Fresnel lens FL1 serving as a reference for creating a new lens in place of the Fresnel lens 5 of the first embodiment. Is shown. The concentric circles indicate the pitch NT of the Fresnel lens, which is a contour line of the lens when the Fresnel lens is replaced with a normal lens, and this indicates that the degree of bending of the Fresnel lens FL1 is indicated. It's okay. A region a is obtained by cutting out the vicinity of the center of the lens, and a region b is obtained by cutting out the peripheral portion of the lens. When the vicinity of the center of the Fresnel lens FL1 is used as the projection image plane as the effective area of the Fresnel lens 5 as in the area a, the refractive power is sufficient in both the vertical and horizontal directions of the lens used, and each position of the projection light PL is The optical path conversion by the Fresnel lens 5 is performed without any problem. Therefore, no problem occurs when the projection light PL is collimated by the Fresnel lens 5. However, when an effective area of the Fresnel lens 5 is cut out from a peripheral part greatly deviating from the center of the Fresnel lens FL1, as in the area b, the pitch NT of the Fresnel lens is particularly large when the Fresnel lens FL1 has a large diameter. Are parallel in the horizontal direction. When the projection light PL is projected from the focal light path, the projection light PL is collimated also in the left-right direction. However, in this embodiment, the principal point R that is the entrance pupil position is shifted from the focal point F by the Fresnel lens. Since the position is closer to 5, the projection light PL diverges in the left-right direction, and the image quality of the projected image is degraded. Therefore, in the present embodiment, the problem is solved by creating a new lens that gives the necessary refractive power to the Fresnel lens 5 by using the curvature in the vertical direction also in the horizontal direction.

  FIG. 6 is a side sectional view for explaining the optical structure of the rear projector type pachinko gaming machine according to the present embodiment. Instead of the Fresnel lens 5 in FIG. 3, in the present embodiment, a lens 105 that is a lens obtained by deforming the Fresnel lens is used. The meanings of the other symbols are the same as in FIG. 3 and the like, but for the sake of explanation, the Fresnel lens FL1 is virtually displayed with a dotted line. In actual use, only the lens 105 is used, but all the references in the optical system such as the optical axis OA and the focal point F in this embodiment are based on the Fresnel lens FL1. Note that an intersection point between a straight line L1 extending perpendicularly to the optical axis OA from the principal point S and a straight line L2 extending parallel to the optical axis OA from the principal point R is defined as a point P. Hereinafter, a method for designing the lens 105 according to the present embodiment will be described.

  FIG. 7 is a front view of the virtual Fresnel lens FL1. Note that the pitch NT is omitted. The lens center of the Fresnel lens FL1 is a principal point S. New lens formation is performed from here. First, a lens obtained by cutting out from the Fresnel lens FL1 around the above-described point P is referred to as a lens FL2. Let the point Q be the intersection of the straight line L1 and the edge of the lens FL2. In the present embodiment, the lens FL2 is further processed in terms of design.

  8A and 8B are diagrams for explaining a design method of the lens 105 used in the present embodiment. FIG. 8A is a front view of the lens FL2. In this case, the pitch NT spreads concentrically from the principal point S, that is, the center of the Fresnel lens FL1, and the lens FL2 is greatly deviated from the principal point S indicating the optical axis position of the Fresnel lens FL1. If used as it is, the problem described in FIG. 5 occurs. Therefore, a new shape of the lens FL3 is obtained by taking a cross section SF from the point P to the point Q, which is the center of the lens FL2, and rotating the cross section SF around the point P as shown in FIG. 8B. . The center point of the lens FL3 is P ′, and the point corresponding to the point Q on the circumference is Q ′. With this design method, the lens FL3 has the same curvature in the horizontal direction as in the vertical direction. However, in this case, since the point P is not the center of the pitch NT, the center point P ′ of the lens FL3 is not smooth. Therefore, in the present embodiment, the region c other than the center point P ′ that causes the discontinuity of the lens FL3 is used as the effective region of the lens 105. For example, as shown in the figure, a region above the center point P ′ is defined as a region c. Thereby, it becomes possible to prevent the divergence of the projection light PL in the left-right direction, and a projection image with good image quality can be obtained. It should be noted that the radius P′Q ′ of the lens FL 3 needs to be larger than the vertical width of the screen 8 so as to be sufficient for projection.

  Although the present embodiment has been described above, the present invention is not only related to pachinko gaming machines, but to other gaming machines such as slot machines and other devices that incorporate all rear projection projectors for observation at close distances. Is also applicable.

1 is a front view of a pachinko gaming machine including a rear projector that is a first embodiment of a gaming machine according to the present invention. FIG. It is a sectional side view for demonstrating the optical system structure of a pachinko game machine provided with a rear projector. It is a figure which shows the optical path of the projection light PL for demonstrating the characteristic in this embodiment. (A) is a sectional side view explaining the optical structure of a general rear projector. (B) is a sectional side view for explaining the optical structure of a rear projector type pachinko gaming machine using oblique projection which has been conventionally used. (C) is the sectional side view which showed again the optical structure of the rear projector type pachinko game machine by this embodiment demonstrated in FIG. 3 for the comparison. It is a figure for demonstrating the subject in 2nd Embodiment, and its solution method. It is a sectional side view for demonstrating the optical structure of the rear projector type | mold pachinko game machine by 2nd Embodiment. It is a front view which shows the mode of the Fresnel lens used as the reference | standard for creating the optical path correction | amendment optical system used for 2nd Embodiment. (A), (b) is a figure for demonstrating the formation method of the optical path correction | amendment optical system used for 2nd Embodiment.

Explanation of symbols

3 ... projector body, 4 ... reflection mirror, 5 ... Fresnel lens, 8 ... screen, 9 ... game board, OL ... projection lens, PL ... projection light, CP ... central optical path, OA ... optical axis of Fresnel lens, E ... observation Point, S: principal point of Fresnel lens, F: focal point of Fresnel lens, R, R '... principal point of projection lens

Claims (12)

A rear projection type projection apparatus main body for projecting a projected image from the back by a projection optical system;
An optical path correction optical system for correcting the optical path of the projection light projected from the projection apparatus main body,
A screen for displaying, as the projection image, the projection light from the projection apparatus main body whose optical path is corrected by the optical path correction optical system,
The projection apparatus main body is arranged so as to be offset so that the principal point of the projection optical system is separated from the optical axis of the optical path correction optical system, and the center part of the light flux of the projection light from the projection apparatus main body A projector is characterized in that a central optical path through which the optical path passes is arranged along a predetermined focal optical path of the optical path correction optical system.   The projector according to claim 1, wherein a focal length of the optical path correction optical system is longer than a projection distance of the projection light.   3. The center optical path of the projection apparatus main body is on a line obtained by extending an optical path perpendicularly passing through the center of the screen in the reverse direction through the optical path correction optical system. The projector according to any one of the above.   4. The projector according to claim 1, wherein the optical path correction optical system is a Fresnel lens that adjusts an emission angle of projection light emitted from the screen. 5.   5. The projector according to claim 4, wherein the optical axis of the Fresnel lens coincides with a parallel line obtained by shifting a perpendicular passing through the center of the screen downward by a predetermined distance.   The optical path correction optical system collimates at least a vertical peripheral optical path of the projection light from the projection apparatus main body around the central optical path with respect to a normal of the screen. Item 6. The projector according to any one of items 5.   7. The projector according to claim 6, wherein the optical path correction optical system further parallelizes a lateral peripheral optical path around the central optical path with respect to a normal of the screen. A rear projection type projection apparatus main body for projecting a projected image from the back by a projection optical system;
It is obtained by changing the curvature of the annular zone of the Fresnel lens, and at least a lateral peripheral optical path around the central optical path through which the central portion of the light beam of the projection light from the projection apparatus main body passes with respect to the central optical path Fresnel lens type optical path correction optical system that is relatively parallel,
A projector comprising: a screen that displays, as the projection image, light projected by the projection apparatus main body whose optical path has been corrected by the optical path correction optical system.   The optical path correcting optical system has a shape obtained by rotating an off-axis optical section of an annular zone of a Fresnel lens around a symmetrical axis spaced in parallel by a predetermined distance from the optical axis of the Fresnel lens. 8. The projector according to 8.   The projector according to claim 1, further comprising an optical path direction changing member that bends an optical path of the projection light between the projection apparatus main body and the screen.   A projector according to any one of claims 1 to 10, and a game board provided with the screen of the projector, wherein an image related to a game is projected onto the screen by the projector. Gaming machine. Projecting projection light for displaying a projected image by the image projection means from the back side of the screen;
A step of correcting the optical path of the projection light by an optical path correction optical system before incidence of the screen,
When performing optical path correction by the optical path correction optical system, the position of the image projection means of the projection light is set to the optical axis of the optical path correction optical system so that the center optical path of the projection light passes through the center of the screen vertically. An image projection method characterized by shifting the image.

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