JP2006133312A - Mangin mirror and projector provided with mangin mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Mangin mirror constituted of a plurality of parts and to provide a projector which attains miniaturization of a set by using the Mangin mirror. <P>SOLUTION: Distribution of wall thickness which changes from a normal line 9 in a cross section including the normal line 9 toward an edge part of the Mangin mirror is measured. A position corresponding to a half of the measured wall thickness distribution at each part is obtained and a shape of a sticking surface 10 formed by connecting those positions with each other is decided. Then a shape of an element A having the sticking surface 10 and a refraction surface 1 and a shape of an element B having the sticking surface 10 and a reflection surface 2 are respectively decided. The element A and the element B are separately molded by molding or the like. Finally the sticking surface 10 of the element A and the sticking surface of the element B are stuck together to produce the Mangin mirror. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a mangin mirror and a rear projector having the mangin mirror, and more particularly, to a mangin mirror composed of a plurality of parts and a projector that is miniaturized using the mangin mirror.

  Projector devices as projection displays in recent years include a rear projector device and a front projector device. Among these, rear projector apparatuses are becoming mainstream that perform enlarged projection using a liquid crystal projector instead of a conventional CRT projector. A rear projector device using this liquid crystal projector is required to be thin and light due to its structure.

  In order to realize this, the rear projector apparatus needs to devise and improve the imaging optical system. As a type of imaging optical system of the rear projector, there is a reflection type imaging optical system in which a projection lens and a reflection mirror are combined, and a spherical or aspherical reflection mirror is used.

  In Patent Document 1, a projection tube for projecting light, a projection lens for enlarging / projecting light disposed on the front surface of the projection tube, a reflecting mirror for reflecting the enlarged / projected light, and the reflecting mirror are reflected. In a rear projector having a screen that forms an image of the reflected light, the scanning of the light in the projection tube is square, and a concave reflecting mirror is arranged as a reflecting mirror, so that the light utilization efficiency is increased and the optical system set A rear projector having a lowered height, particularly a screen position, has been proposed.

  In Patent Document 2, in the reflective imaging optical system including the first to fourth four reflecting mirrors, the first reflecting mirror is separated from the image forming body by a reflecting surface formed of a concave curved surface of the first reflecting mirror. The second reflecting mirror is disposed so that the reflecting surface formed of the convex curved surface of the second reflecting mirror faces the light beam from the first reflecting mirror, and the third reflecting mirror is The reflecting surface composed of the convex curved surface of the third reflecting mirror is arranged toward the light beam from the second reflecting mirror, and the fourth reflecting mirror is the reflecting surface composed of the convex curved surface of the fourth reflecting mirror. Is arranged toward the light flux from the third reflecting mirror, so that the distance between the reflecting mirrors can be shortened and the size of each reflecting mirror can be reduced. A reflection type imaging optical system capable of achieving an angle of view has been proposed.

  However, a conventional reflective imaging optical system uses a reflecting mirror having a curved surface, and a Mangin mirror is not used. The Mangin mirror has a refracting surface 1 and a reflecting surface 2 as shown in FIG. The light beam 3 emitted from the projection lens first enters the refracting surface 1 and is refracted. Next, an optical path is taken in which the light is reflected by the reflecting mirror 2 and is again refracted by the refractive surface 1. The reflecting surface 2 may be a flat surface, but by taking a curved surface shape, the controllability and condensing property of the traveling direction of the light beam are improved.

As described above, since the Mangin mirror has a plurality of surfaces having optical functions, the design parameters are increased as compared with a general reflecting mirror, and the degree of freedom in designing the projector device is increased.
JP-A-7-87428 JP 2002-40326 A

  However, when using a Mangin mirror, as shown in FIG. 8, it is preferable that the region where the light beam enters and the region where it exits are different on the refracting surface 1. When the incident area and the emission area overlap, as shown in FIG. 9, the light emitted from the emission area and the light emitted from the incidence area become discontinuous at the boundary between the emission area and the incidence area. The projected image is generally continuous without such a singular point. Therefore, when the incident area and the emission area overlap, a good projection image cannot be obtained.

  Therefore, in order to make the incident area and the emission area separated from each other with the optical axis as a boundary, it is necessary to increase the optical path length from the refractive surface to the reflecting surface. Specifically, as shown in FIG. 10, the shorter the distance from the refracting surface to the reflecting surface, the worse the separation, and the light cannot be separated unless it is incident at a very shallow angle. However, in order to make the light incident at a shallow angle, the Mangin mirror has to be installed in a nearly horizontal state, and the light beam emitted from the Mangin mirror does not go in the preferred direction, and the optical path folding function cannot be performed. Therefore, it becomes difficult to realize a rear projector device with a small depth.

  As described above, when a mangin mirror is used in the rear projector device, the mangin mirror is required to have a predetermined thickness. When the mangin mirror is manufactured by a molding method such as injection molding, the manufacturing time increases as the wall thickness increases. become longer. For example, when the thickness of the Mangin mirror is doubled, the time required for molding takes twice or more, and the mass productivity is reduced.

  Therefore, the present invention measures the thickness distribution that changes from the center to the end of the mangin mirror in the cross section of the center of the mangin mirror, and corresponds to 1/2 of the measured thickness distribution of each part. Determine the position, determine the shape of the bonding surface connecting the positions, determine the shape of the element having the bonding surface and the refracting surface, and the shape of the element having the bonding surface and the reflection surface, and mold each element, etc. The object is to propose a Mangin mirror in which the bonding surfaces of each element are bonded together, and a projector having the Mangin mirror.

  The invention according to claim 1 is a Mangin mirror having a refracting surface and a reflecting surface, and includes at least one refracting element having the refracting surface and a reflecting element having the reflecting surface, and the refracting element and the reflecting surface. It has a hybrid structure in which an element is bonded.

  According to a second aspect of the present invention, in the Mangin mirror according to the first aspect, the thickness distributions of the refractive element and the reflective element are equal.

  According to a third aspect of the present invention, in the Mangin mirror according to the first aspect, the bonding surface is a spherical surface.

  The invention according to claim 4 is the Mangin mirror according to any one of claims 1 to 3, characterized in that the thickness distribution of the element having a large tolerance sensitivity is smaller than the thickness distribution of the element having a small tolerance sensitivity. To do.

  According to a fifth aspect of the present invention, in the Mangin mirror according to any one of the first to fourth aspects, the refractive index of each element is different.

  A sixth aspect of the present invention is the Mangin mirror according to any one of the first to fifth aspects, wherein the material dispersion value of each element is different.

  A projector according to a seventh aspect includes the Mangin mirror according to any one of the first to sixth aspects.

  The projector according to claim 8 is characterized in that the projector is a front projector.

  The projector according to claim 9 is characterized in that the projector is a rear projector.

  The present invention measures the distribution of thickness changing from the center to the end of the mangin mirror in the cross section of the center of the mangin mirror, and positions corresponding to 1/2 of the measured thickness distribution of each part. Determine the shape of the bonding surface connecting the positions, determine the shape of the element having the bonding surface and the refracting surface and the shape of the element having the bonding surface and the reflection surface, and separately form each element by molding, etc. Finally, by sticking the bonding surfaces of the elements together, it is possible to avoid an increase in manufacturing time accompanying the increase in the thickness of the Mangin mirror, and to ensure a degree of design freedom.

  A method for manufacturing a mangin mirror and a rear projector using the mangin mirror according to an embodiment of the present invention will be described below.

  1 and 2 are cross-sectional views of a mangin mirror produced by the method for producing a mangin mirror according to the present embodiment. The Mangin mirror according to this embodiment is designed so that the refractive surface 1 and the reflecting surface 2 of the Mangin mirror are symmetric with respect to the normal 9 passing through the center of the surface. When producing the Mangin mirror, first, the distribution of the thickness that changes from the normal 9 to the end of the Mangin mirror in the cross section including the normal 9 is measured. Then, a position corresponding to 1/2 of the measured thickness distribution of each part is obtained, and the shape of the bonding surface 10 is determined by a curved surface or a spherical surface including a curve connecting the positions. Next, the shapes of the element A having the bonding surface 10 and the refractive surface 1 and the element B having the bonding surface 10 and the reflection surface 2 are determined. Element A and element B are separately molded by molding or the like. Finally, the Mangin mirror is created by bonding the bonding surface 10 of the element A and the bonding surface of the element B together.

  That is, in the conventional method for manufacturing a mangin mirror, as described above, as the thickness of the mangin mirror increases, it takes a long time to form the mangin mirror. On the other hand, in the present embodiment, a Mangin mirror is created by combining a plurality of thin elements. Here, the time required for forming each thin element is shorter than the time required for forming the thick mangin mirror. Therefore, the manufacturing method according to the present embodiment, in which a plurality of elements are formed and bonded together, is created in a shorter time than the conventional manufacturing method of manufacturing a mangin mirror in one step. be able to. When each element is manufactured by molding, it is desirable to use, for example, ZEONEX as a material.

  In addition, as shown in FIG. 3, the bonding surface 10 can be determined with an arc 10. Specifically, first, an arc 10 is defined in a cross section including the normal line 9, and a curved surface or a spherical surface having the arc 10 is defined as a bonding surface 10. Next, the shapes of the element A having the bonding surface 10 and the refractive surface 1 and the element B having the bonding surface 10 and the reflection surface 2 are determined. Element A and element B are separately molded by molding or the like. Finally, the Mangin mirror is created by bonding the bonding surface 10 of the element A and the bonding surface 10 of the element B together.

  Further, as shown in FIGS. 4 and 5, it is possible to create one mangin mirror by bonding three elements. As shown in FIGS. 5 and 3, by defining the shape of the bonding surface (10, 11, 12) as a spherical surface, the shape of the bonding surface (10, 11, 12) becomes simple, The time required for molding each element can be shortened.

  Also, a change in refraction angle when the curvature is changed from the ideal refracting surface 1 by simulation (hereinafter referred to as tolerance sensitivity) and a change in reflection angle when the curvature is changed from the ideal reflecting surface 2 (hereinafter referred to as tolerance sensitivity). , And a bonding surface 10 having a shape similar to the surface having the larger tolerance sensitivity (a surface parallel to the refractive surface 1 or the reflecting surface 2). By making the surface of the larger tolerance sensitivity and the bonding surface 10 the same shape, the surface of the larger tolerance sensitivity and the bonding surface 10 are parallel to each other, and the balance of the manufacturing accuracy required for each element. Can be improved.

  Further, by using materials having different refractive indexes for each element, different refractive powers can be given to the incident light in each element, and the degree of freedom in design can be increased. Furthermore, chromatic aberration can be corrected by selecting materials having different material dispersion values for each element.

  Next, a rear projector apparatus having a Mangin mirror according to the present embodiment will be described with reference to FIG. In this embodiment, an example in which the Mangin mirror is used for a rear projector will be described. However, it can be used for other projectors such as a front projector.

  The rear projector device shown in FIG. 6 includes a projection lens 4, a reflection mirror 5, a mangin mirror 6 according to this embodiment, a reflection mirror 7, and a screen 8. By adjusting the installation angle of the reflection mirror 5, the incident angle of light to the Mangin mirror 6 can be changed, and the depth of the rear projector device can be shortened.

It is sectional drawing of the mangin mirror which concerns on this embodiment. It is a block diagram of the Mangin mirror which concerns on this embodiment. It is a block diagram of the Mangin mirror which concerns on this embodiment. It is a block diagram of the Mangin mirror which concerns on this embodiment. It is a block diagram of the Mangin mirror which concerns on this embodiment. It is the schematic of the rear projector apparatus which has the Mangin mirror which concerns on this embodiment. It is a figure which shows a mode that light is radiate | emitted from the conventional mangin mirror. It is a figure which shows a mode that light is radiate | emitted from the conventional mangin mirror. It is a figure which shows a mode that light is radiate | emitted from the conventional mangin mirror. It is a figure which shows a mode that light is radiate | emitted from the conventional mangin mirror.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refractive surface 2 Reflective surface 3 Light beam 4 Projection lens 5 Reflective mirror 6 Mangin mirror 7 Reflective mirror 8 Screen 9 Normal 10, 11, 12 Bonding surface

Claims (9)

In a Mangin mirror having a refracting surface and a reflecting surface,
At least one refractive element having the refractive surface;
A reflective element having the reflective surface;
A Mangin mirror having a hybrid structure in which the refractive element and the reflective element are bonded together.   2. The Mangin mirror according to claim 1, wherein the refractive element and the reflective element have the same thickness distribution.   2. The Mangin mirror according to claim 1, wherein the bonding surface is a spherical surface.   4. The Mangin mirror according to claim 1, wherein a thickness distribution of an element having a high tolerance sensitivity is smaller than a thickness distribution of an element having a low tolerance sensitivity. 5.   The Mangin mirror according to any one of claims 1 to 4, wherein each element has a different refractive index.   6. The Mangin mirror according to claim 1, wherein a material dispersion value of each element is different.   A projector comprising the Mangin mirror according to any one of claims 1 to 6.   The projector according to claim 7, wherein the projector is a front projector.   The projector according to claim 7, wherein the projector is a rear projector.

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