JP4612378B2 - Lens holding unit and image display device - Google Patents

Description

  The present invention relates to a lens unit and a lens holding unit suitable for an image display apparatus that enlarges and projects an image displayed on a light valve such as liquid crystal or DMD onto a screen.

2. Description of the Related Art A rear type projector apparatus that projects projection light from a light modulator (light valve) that modulates light with an image signal to form an image onto a screen from a rear surface is known. Patent Document 1 discloses a projector device that switches a light path by arranging a prism or mirror that bends the light path in the middle of a lens group that constitutes a lens system.
JP-A-6-138386

  In a lens unit including a plurality of lenses, each lens has a disk shape, and the plurality of lenses are linearly arranged so that the optical axis coincides with the center of the lens. Therefore, the outer peripheral shape of the plurality of lenses arranged in a line in the optical axis direction is the same at any angle around the optical axis. Therefore, when providing a holder (lens holding unit) that supports the radial direction (radial direction) of a plurality of lenses, the holder is equally divided around the optical axis at an appropriate angle, and the inner and outer shapes are the same. It becomes possible to divide into subunits. Even if the arrangement of multiple lenses that support the inside is the same at any angle around the optical axis, the structure that supports them need not be the same at any angle around the optical axis, and the appearance of the holder Is the same. Considering the ease of assembly when assembling the lens unit by attaching the lens to the holder, the ease of molding with plastic, etc., the shape of the holder divided into two along the optical axis is the center. It is preferable to make them the same, and it is considered that subunits having the same shape divided into two around the optical axis are joined to form one holder.

  In this specification, such a configuration of the lens holder is referred to as a clamshell type, and the present invention relates to a clamshell type lens holder (lens holding unit). Since the clamshell type holder joins two subunits manufactured from one mold, the lens holding unit can be manufactured or assembled at low cost. Further, since the same structure and the same tolerances are supported by the subunits in the radial direction (radial direction), there is an advantage that the center of the lens or the optical axis can be easily aligned. Therefore, it is preferable to use a clamshell type holder in a projection lens system for a rear projector that is expected to obtain image quality equivalent to that of a conventional television by using a projection image.

  However, a major problem of the clamshell type lens holding unit is that it cannot cope with an asymmetric shape around the optical axis. For example, when the optical path is bent in the lens system, the optical axis is bent. Therefore, the lens arrangement is not symmetrical about any optical axis, and a clamshell type lens holder cannot be applied. It is possible to divide the lens groups having different optical axis directions into holders for holding them individually, and to make each holder a clamshell type. However, the clamshell type cannot be adopted because the part where the optical path is bent is the part where the optical axes intersect.

  Therefore, an object of the present invention is to provide a clamshell type lens holding unit and a lens unit that can support a plurality of lenses including an optical element that bends an optical path from the radial direction.

One embodiment of the present invention includes a first shell for holding the first lens group, a second shell for holding the second lens group, the first lens group, and the second lens group. A connecting shell for holding an optical element that bends the optical path between the lens groups, and the connecting shell is two connecting subunits having the same shape and joined around the optical axis. The optical element is mounted only in the optical path of one of the connecting subunits, and further, a first structure for connecting to the first shell, and for connecting to the second shell A lens holding unit having at least one of the first structure and the second structure at two conjugate positions.

At least one of the first shell and the second shell may include two subunits having the same shape and joined around the optical axis.

Another aspect of the present invention includes a first shell for holding the first lens group and a second shell for holding the second lens group, and the first shell The shell includes a connection portion for holding an optical element that bends the optical path between the first lens group and the second lens group, and the first shell is bonded around the optical axis. Two first subunits having the same shape, and at least in the connection portion, the optical element is attached only to the optical path of one of the first subunits, and further connected to the second shell. This is a lens holding unit provided with two conjugate positions at the second structure.

The lens holding unit is for a lens unit that projects projection light from an optical modulator onto a screen, and one of the first lens group and the second lens group is a lens unit of the optical modulator. The other lens group may be located on the screen side.

Another aspect of the present invention is the above-described lens holding unit, the first lens group held by the first shell, and the second lens group held by the second shell. And an optical element that bends the optical path between the first lens group and the second lens group.

Another aspect of the present invention includes the lens unit described above, a light modulator, and a screen, and the projection light from the light modulator is bent and projected onto the screen by the lens unit. This is an image display device.

  In a system that projects an image from a direction inclined by a predetermined angle with respect to a screen such as a rear projector device (an oblique projection system), an image tilted in a trapezoidal shape is projected with respect to the screen. Therefore, in order to project an image of a desired size and shape on the screen, an image projected on the screen in advance by the light valve is formed by correcting the keystone and projected using the lens unit. For this reason, the image that passes through the lens unit is an image that has been corrected so as to be entirely trapezoidal, and is not a square or rectangular image. When trying to use the lens unit effectively, that is, when trying to project a large image with a small-diameter lens, the lens area should be used to enlarge and project the image as effectively as possible. Therefore, it is desirable to process the long side of the trapezoidal image at or near the lens diameter and the short side of the trapezoidal image around the lens.

  In a thin rear projector, the inclination between the screen and the optical axis of the lens becomes large, and a trapezoidal correction in which the ratio of the long side to the short side is large is often required. At this time, the most effective use of the lens is to input an image with the long side of the trapezoid matched to the diameter of the lens. Therefore, half the area of the lens is used for image processing. Similarly, in the optical element that bends the optical axis, if the optical system is designed so that half the area is used with respect to the optical axis, the optical element does not require symmetry around the optical axis. . For this reason, also in the holder which supports an optical element, the shape which supports an optical element does not need the symmetry around an optical axis.

  Therefore, if the other elements of the portion of the holder that bends the optical path can be made symmetrical about any one of the optical axes, the shell of the portion to be folded can also be a clamshell type. For this reason, in the present invention, the part for holding the optical element that bends the optical path is a shell (connection shell) independent of other parts, and the connection shell is connected to the other shell. Yes. In this connection shell, only the optical path of one subunit is used. The connecting shell includes a first structure for connecting to the first shell and a second structure for connecting to the second shell, but the first structure and the second structure By providing at least one of the two conjugate positions, the structure is symmetrical around the optical axis of the second shell (second optical axis) or the optical axis of the first shell (first optical axis). The connecting shell is a clamshell type that can be provided by a half-cracked subunit of the same structure. Although the angle at which the optical path is bent is not limited to 90 degrees, a clamshell for a lens unit in which the optical path is bent 90 degrees has a relatively simple configuration.

  That is, the lens holding unit of the present invention includes a first shell for holding the first lens group, a second shell for holding the second lens group, the first lens group, and the second lens group. And a connecting shell for holding an optical element that bends the optical path between the two lens groups, and the connecting shell has two connecting subunits having the same shape and joined around the optical axis. Is provided. In the connection shell, only the optical path of one of the connection subunits is used effectively. Furthermore, the connecting shell, that is, the connecting subunit includes a first structure for connecting to the first shell and a second structure for connecting to the second shell, At least one of the first structure and the second structure is provided at two conjugate positions. The two conjugate positions mean that the positions are symmetrical about the first optical axis or the second optical axis.

  If the first lens group is symmetrically arranged around the first optical axis, that is, if the lens arrangement is along the first optical axis, the first shell can be a clamshell. If the second lens group is symmetrically arranged around the second optical axis, that is, if the lens arrangement is along the second optical axis, the second shell can also be a clamshell. Therefore, the first shell is a clam shell including two first subunits of the same shape joined around the optical axis (first optical axis), and the second shell is the optical axis (first optical axis). A clamshell including two second subunits of the same shape joined around the two optical axes). For this reason, according to the present invention, the lens holding unit that supports a plurality of lenses constituting a lens unit of a type whose optical path is bent in the middle can be made a clamshell type. Therefore, it is possible to manufacture a lens unit of a type in which the optical path is bent in the middle using a clamshell, and it is possible to provide a lens unit that is low in cost, high in yield, and high in imaging performance.

  If the first lens group has a symmetrical shape around the first optical axis, a structure connected to the second shell is provided at a conjugate position, so that the first lens group and an optical element such as a prism are provided. It is possible to make the shell that holds the element integrally a clamshell type. In other words, the present invention has a first shell for holding the first lens group and a second shell for holding the second lens group, and the first shell is the first shell. A connection portion for holding an optical element that bends the optical path between the lens group and the second lens group is provided, and the first shell has two first shapes having the same shape bonded around the optical axis. And a lens holding unit in which only the optical path of the first subunit is effectively used at least in the connection portion. In this lens holding unit, the first shell, that is, the first subunit, further includes a second structure for connecting to the second shell at two conjugate positions.

  When the lens holding unit of the present invention is for a lens unit that projects the projection light from the light modulator onto the screen, one of the first lens group and the second lens group is one of the light modulators. The other lens group is located on the screen side.

  The lens unit of the present invention can provide an image display device that has an optical modulator and a screen, and that projects the projection light from the optical modulator and projects it onto the screen at a low cost. This type of image display apparatus is suitable as a thin rear projector.

  FIG. 1 shows an outline of a rear projector device 1 provided with a lens unit of the present invention. The rear projector apparatus 1 includes a light source 3, a light modulator (light valve) 4 that forms an image by modulating light from the light source 3 using an image signal, and an image of the light valve 4. A lens unit 5 for projecting and a mirror 7 for reflecting the projection light 8 and guiding it to a screen 9 are provided. A screen 9 is disposed on the surface of the housing 2, and the image of the light valve 4 is enlarged and projected onto the screen 9. As the light valve 4, a liquid crystal panel, a DMD panel using a micromirror element, or the like can be employed.

  FIG. 2 shows an outline of the lens unit 5 for projection. The lens unit 5 includes a plurality of lenses 20, a prism 6 for bending an optical path inside the lens unit 5, and a lens holding unit 10 that stores them. The lens holding unit 10 has an L shape as a whole, and outputs projection light by bending light 90 degrees inside the lens unit 5 by the built-in prism 6. This projection light is projected onto the screen 9 via the mirror 7 to form an image. The plurality of lenses 20 are arranged separately in a first lens group 21, a second lens group 22, and a third lens group 23 from the screen 9 side. The first lens group 21 is disposed on the screen side of the prism 6, and the second lens group 22 and the third lens group 23 are disposed on the light valve side of the prism 6.

  The lens holding unit 10 of the lens unit 5 includes a cylindrical first shell 11 for storing and holding the first lens group 21 and a cylindrical shape for storing and holding the second lens group 22. A second shell 12, a cylindrical third shell 13 for housing and holding the third lens group 23, a fourth shell 14 for holding the prism 6 and having a light path bent 90 degrees; It has. Among these shells (holders) 11 to 14, the position of the third shell 13 and the second shell 12 is adjusted with respect to the light valve 4 side of the second shell 12. The mounting structure is fixed later. The fourth shell 14 and the second shell 12 have a connection structure that is fixed to the screen 9 side of the second shell 12. The first shell 11 and the fourth shell 14 have a connection structure that is fixed to the side of the screen 9 bent by 90 degrees of the fourth shell 14 after the first shell 11 is adjusted in position. Yes.

  FIG. 3 schematically shows an optical system constituted by the lens groups 21 to 23 of the lens unit 5 and the prism 6. In this figure, the number of lenses in the lens groups 21, 22 and 23 is omitted, and the optical path is also schematically shown. The projection light 29 of the image formed by the light valve 4 is processed by the third lens group 23 and the second lens group 22, and at the position of the prism 6, the area behind the paper surface from the optical axis 26 is used. The angle can be changed. Then, the projection light 29 that is three-dimensionally reflected by the prism 6 in the 90-degree direction is processed by the first lens group 21 and output toward the screen 9. Therefore, the prism 6 only needs to have a portion on the rear side of the paper surface from the optical axes 25 and 26, and a portion 96 indicated by a broken line is unnecessary and is not mounted on the lens unit 5. For this reason, in the fourth shell 14 that covers the prism 6, an area that is half the cross section of the optical path formed inside is optically effectively used.

  The projector apparatus 1 of this example employs an optical system that projects projection light obliquely from below onto a screen 9 via a mirror 7 by a projection lens unit 5. Therefore, in order to prevent trapezoidal distortion of the image on the screen 9, an image whose keystone is corrected by the light valve 4 is formed. When projecting an image on the screen 9, if the trapezoidal distortion is large, it is necessary to match the base of the corrected image with the diameter of the lens, and to process the projection light using a half area of the lens. As described above, can be used most effectively. In the lens unit 5 of this example, also in the prism 6 that bends the optical path by 90 degrees, the optically effective portion has an optical design that is limited to the rear side of the drawing with respect to the optical axes 25 and 26. If the prism 6 is arranged so that the projection light is reflected from the second lens group 22 to the first lens group 21 in the region, desired optical performance can be obtained. Conversely, since effective projection light does not reach other regions, it can be said that it is desirable to absorb the light in other regions without reflecting.

  FIG. 4 is a perspective view showing details of the appearance of the lens unit 5. FIG. 5 is a perspective view showing the lens holding unit 10 of the lens unit 5 separated into shells. In this example, each of the second shell 12, the third shell 13, and the fourth shell 14 is a clamshell type holder, and is composed of sub-units of the same shape that are divided into two on the upper and lower sides or on the left and right of the optical axis. These are joined together by a method such as screwing to form one substantially cylindrical shell. For this reason, the second shell 12 includes two second subunits 32 having the same shape, the third shell 13 includes two third subunits 33 having the same shape, and the fourth shell 14 is the same. Two fourth subunits 34 having a shape are provided. Since the first shell 11 has a configuration in which the arrangement of the first lens group 21 can be easily inserted from one side, the clamshell type is not adopted. However, like the other shells, the first shell 11 can also be a clamshell type holder.

  The second shell 12 and the third shell 13 are substantially cylindrical, and hold the second lens group 22 and the third lens group 23 from the radial direction inside. These shells 12 and 13 are fixed by screwing or the like after inserting the third shell 13 into the second shell 12 and adjusting the position of the third shell 13. As a result, the optical distance of the optical axis 26 between the second lens group 22 held by the second shell 12 and the third lens group 23 held by the third shell 13 is adjusted, and the focal point is adjusted. A lens unit with good optical performance such as correction and aberration correction can be provided.

  The joint portion of the second shell 12 and the fourth shell 14 is a flange 16 and 17a that is nearly square as a whole. By overlapping and screwing them, the second lens group 22 can be joined. The prism 6 is fixed at a desired distance. A funnel-shaped connection port 19 for inserting the first shell 11 is formed at a position perpendicular to the flange 17 a of the shell 14. The first shell 11 is connected to the fourth shell 14 by screwing or the like after adjusting the position in the direction of the optical axis 25. Thereby, the optical distance of the optical axis 25 between the second lens group 22 held by the second shell 12 and the first lens group 21 held by the first shell 11 is adjusted, and the focal point is adjusted. A lens unit with good optical performance such as correction and aberration correction can be provided.

  The fourth shell 14 includes a connection structure (second connection structure) 18 including flanges 17 a and 17 b that can be connected to the second shell 12 at positions symmetrical to the optical axis 25. For this reason, the outer shape of the fourth shell 14 for connection is symmetric with respect to the optical axis 25 of the first shell 11. Further, the connection port 19 with the first shell 11 is the first connection structure, and the basic form is a circular shape and is symmetric with respect to the optical axis 25. Therefore, even if the fourth shell 14 is rotated 180 degrees around the optical axis 25, the fourth shell 14 can be attached to the second shell 12, and the first shell 11 is attached to the connection port 19. Can do. The flanges 17a and 17b of the connection structure 18 formed at the rotationally symmetric and conjugate positions of the fourth shell 14 have screw holes 17s at an angular interval facing the screw holes 16s of the flange 16 of the second shell 12. Is formed. Furthermore, a hole 17h through which a screwing tool is passed is formed at a position slightly shifted from each screw hole 17s. In these flanges 17a and 17b, the positions of the screw hole 17s and the tool hole 17h are switched. ing. Therefore, even if the flange 17b is not connected to the second shell 12, the flanges 17a and 16 can be screwed through the flange 17b.

  FIG. 6 shows a perspective view of the second subunit 32, the third subunit 33, and the fourth subunit 34. The second subunit 32 and the third subunit 33 have a shape obtained by halving the substantially cylindrical second shell 12 and third shell 13 along the optical axis 26, respectively, and have a lens inside. The structure 27 and 28 which can be inserted and fixed are provided. Therefore, the shells 12 to 14 can be assembled by connecting the half-cracked subunits 32 to 34 around the optical axis. When the lens unit 5 is assembled, the lenses constituting the second lens group 22 and the third lens group 23 are inserted into the second subunit 32 and the third subunit 33, respectively, and the other second subunit 32 and the third subunit 33 are inserted. The subunit 32 and the third subunit 33 are joined. Accordingly, the second lens group 22 and the third lens group 23 can be held from the radial direction by the second shell 12 and the third shell 13, respectively. In the case of a clamshell type holder that joins subunits of the same shape, the two subunits to be joined are formed from the same mold, and the manufacturing tolerances of those subunits are the same. Therefore, since the plurality of lenses are held by the same manufacturing tolerance subunit, the second lens group 22 and the third lens group 23 can be held in a straight line with high accuracy around the optical axis 26. . Therefore, it is easy to align the optical axes of a plurality of lenses constituting the lens unit 5, and a lens unit with high optical performance can be manufactured with high yield and low cost.

  FIG. 7 is a perspective view showing the structure of the fourth subunit 34 for connection. The fourth subunit 34 is a semiconical concave portion that forms a triangular prism-shaped storage portion 41 that stores the triangular prism 6 that is an optical element that bends the optical path, and a connection portion 19 into which the first shell 11 is inserted. 45 and a connection structure 18 having flanges 17a and 17b for connecting to the second shell 12. The triangular prism-shaped storage portion 41 has an opening on a side 42 facing one flange 17a and a side 43 facing the connection port 19 with the first shell 11, and allows light to pass therethrough. Therefore, the storage portion 41 of the fourth shell 14 bends the light incident from the opening 42 facing one side of the connection structures 18 on both sides by the prism 6 by 90 degrees and directs the light from the opening 43 to the connection port 19. And becomes an optical path to be emitted.

  When two subunits 34 having the same configuration are combined around the optical axis 25 as shown in FIG. 7, the connection structure 18 is formed at a position symmetrical to the optical axis 25, so that it is connected to the second shell 12. The flange 17a is assembled, and the fourth shell 14 that can be connected to the second shell 12 is assembled. On the other hand, the optical path 41 to which the prism 6 can be attached intersects with each other, and when the optical path 41 of one subunit 34 is arranged from the second shell 12 to the first shell 11 as described above, The optical path 41 of the subunit 34 is directed to the side opposite to the second shell 12, and the projection light does not pass effectively. However, as described with reference to FIG. 3, in the lens unit 5 of this example, if the half of the plane perpendicular to the optical axes 25 and 26 is effective at the portion where the prism 6 is disposed and the optical axis is bent. It has a good optical design. Therefore, the connecting shell 14 in which the subunits 34 having the same shape are combined has no optical disadvantage, and effectively reflects the projection light 29 from the second lens group 22 of the second shell 12. The direction is changed by 90 degrees and supplied to the first lens group 21 of the first shell 11.

  One of the subunits 34 of the fourth shell 14 is not used optically. Therefore, the prism 6 is not installed in the optical path 41 of one subunit 34. Further, the opening 42 of the subunit 34 where the prism 6 is not disposed is shielded from light by an appropriate sealing member 49 such as a black tape.

  In this example, the connecting shell 14 is made independent of the first shell 11 and the second shell 12, but it is also possible to form a clamshell type integrally with these shells. One configuration is a configuration in which the first shell 11 is a clam shell and is integrated with the fourth shell 14. Since there is no place to adjust the distance between the lenses in the direction in which the optical path is bent by 90 degrees, the flexibility of the focus adjustment may be reduced, but the merit that the number of parts constituting the lens holding unit 10 can be further reduced. There is. Another configuration is a configuration in which the second shell 12 and the connecting shell 14 are integrated. In this case, it is necessary to form the first connection structure 19 for the first shell 11 at a position symmetrical to the optical axis 26. In this configuration, since the second shell 12 and the fourth shell 14 are integrated, the shell size becomes large, and it may be difficult to maintain the molding accuracy. However, there is an advantage that the flange for connecting the second shell 12 and the fourth shell 14 can be omitted, and the number of parts constituting the lens holding unit 10 can be reduced.

  Moreover, although the example which employ | adopted the prism as an optical element which bends an optical path is shown above, this invention can be provided also in the lens unit which employ | adopted other optical elements, such as a mirror. Further, the angle at which the optical path is bent is not limited to 90 degrees. For example, in the fourth shell 14, when the second shell 12 and the first shell 11 are combined at an angle of 90 degrees or more, the second connection structure 18 is positioned at a conjugate position, that is, the optical axis 25. It is necessary to provide a symmetrical position and the same angle with respect to the optical axis 25.

  Further, the rear projector apparatus, the lens system and the lens holding unit suitable for the rear projector apparatus have been described. However, the lens holding unit and the lens unit of the present invention can be applied to all systems that project an image. Further, the present invention is not limited to a system that projects an image, and can be applied to an optical device or an optical system that uses a lens.

It is a figure which shows schematic structure of a rear projector. It is a figure which shows schematic structure of the lens unit of this invention. It is a figure which shows the optical system of the lens unit of this invention. It is a perspective view which shows the external appearance of a lens unit in the state which connected each shell. It is a perspective view which shows the external appearance of a lens unit in the state which isolate | separated each shell. It is a perspective view which shows the subunit which comprises each shell. It is a perspective view which shows the detail of the 4th shell for a connection.

1 Rear projector device 4 Light valve (light modulator)
5 Lens Unit 6 Prism 9 Screen 10 Lens Holding Unit 11 First Shell 12 Second Shell 13 Third Shell 14 Fourth Shell (Connection Shell)
18 2nd connection structure 19 1st connection structure 21 1st lens group 22 2nd lens group 23 3rd lens group 32 2nd subunit 33 3rd subunit 34 4th subunit

Claims (6)

A first shell for holding the first lens group;
A second shell for holding the second lens group;
A connection shell for holding an optical element that bends the optical path between the first lens group and the second lens group;
The connection shell includes two connection subunits of the same shape joined around an optical axis, and the optical element is attached only to the optical path of one of the connection subunits, A first structure for connecting to the first shell; and a second structure for connecting to the second shell, wherein at least one of the first structure and the second structure is conjugated. A lens holding unit provided at two positions.   2. The lens holding unit according to claim 1, wherein at least one of the first shell and the second shell includes two subunits having the same shape and joined together around an optical axis. A first shell for holding the first lens group;
A second shell for holding the second lens group;
The first shell includes a connection portion for holding an optical element that bends an optical path between the first lens group and the second lens group;
The first shell is provided with two first subunit of the same shape joined around the optical axis, at least in the connecting portion, the optical element only in the optical path of one of the first subunit And a lens holding unit having a second structure for connecting to the second shell at two conjugate positions.   4. The lens holding unit according to claim 1, wherein the lens holding unit is for a lens unit that projects projection light from an optical modulator onto a screen, and one of the first lens group and the second lens group. A lens holding unit, wherein the group is located on the light modulator side and the other lens group is located on the screen side.   5. The lens holding unit according to claim 4, a first lens group held by the first shell, a second lens group held by the second shell, and the first lens group. A lens unit having an optical element for bending the optical path between the second lens group and the second lens group; The lens unit according to claim 5, a light modulator, and a screen,
An image display device that projects the projection light from the light modulator on the screen by the lens unit.

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