WO2011077688A1

WO2011077688A1 - Lens optical system, image display device and head-up display

Info

Publication number: WO2011077688A1
Application number: PCT/JP2010/007359
Authority: WO
Inventors: 浩之根本
Original assignee: 日本板硝子株式会社
Priority date: 2009-12-21
Filing date: 2010-12-20
Publication date: 2011-06-30
Also published as: JP2013047698A

Abstract

A lens optical system is provided with, in order from the object side, a first convex lens group (20) comprising multiple planarly disposed first convex lens elements (21), a second convex lens group (22) comprising multiple planarly disposed second convex lens elements (23), and a third convex lens group (24) comprising multiple planarly disposed third convex lens elements (25). The lens diameter and lens pitch of the convex lenses increase in the order of first convex lens group (20), second convex lens group (22), and third convex lens group (24). Further, the distance between the second convex lens group and the third convex lens group is greater than the distance between the first convex lens group and the second convex lens group.

Description

Lens optical system, image display device, and head-up display

The present invention relates to a lens optical system, and an image display device and a head-up display using the lens optical system.

Conventionally, a head-up display that displays information such as the vehicle speed in front of the front window of the vehicle is known. The driver can check information such as the vehicle speed without much movement of the line of sight while driving the vehicle by superimposing the display image displayed by the head-up display and the scenery in front of the vehicle.

FIG. 1 shows an example of a conventional head-up display. This head-up display is disclosed in Patent Document 1. As shown in FIG. 1, the optical unit 80 arranged on the dashboard of the car includes a display 88 that is an image display unit, a plane mirror 81, and a concave mirror 82. The light from the display 88 is reflected by the plane mirror 81 and the concave mirror 82 which is a magnifying optical system, passes through the exit window 87 and is reflected toward the driver by the combiner 102 provided on the front window 101. For the driver, the displayed virtual image 103 is visually recognized in front.

The role of the plane mirror 81 is to bend the optical path when the optical path from the display 88 to the concave mirror 82 cannot be made straight due to spatial restrictions of the optical unit 80.

FIG. 2 is an explanatory view of the far-increasing display by the concave mirror 82. The distance between the display 88 and the concave mirror 82 (center point is Q) is L ₁ , the distance of QP ′ when the virtual image of the concave mirror at the point P on the display is P ′ is L ₂ , the point Q and the combiner 102 The distance between the center point R is L ₃ and the distance between the point R and the driver's eyes (point E: viewpoint) is L ₄ .

The distance between the driver's eye position (point E) and the virtual image P ″ formed forward is L ₂ + L ₃ + L _4. Of these, L ₃ and L ₄ are determined by the car, and in the case of a passenger car, is about 1 m. Therefore, as can view the display and view outside the vehicle without focus movement of the eye, in order to display more virtual image far away, it is necessary to increase the L _2.

One method of increasing the L ₂ is an optical path length L ₁ extending from a focal length shorter (smaller radius of curvature) to display 88 of the concave mirror 82 to the concave mirror 82 in a short state than the focal length of the concave mirror, It should be as close to the focal length as possible. Thereby, a large enlargement magnification can be obtained, and the display 88 can be small.

Alternatively, (large curvature radius) long focal length using a concave mirror 82, there is a long take ways L _1. With this method, the display distance can be increased even with a low magnification. For example, like the optical unit shown in FIG. 3, plane mirrors 91 and 92 and a concave mirror 93 are provided so that the optical paths overlap in a limited space. As a result, the optical unit is miniaturized.

Japanese Patent Laid-Open No. 06-55957

However, in the conventional head-up display optical unit of Figure 1, in order to display more virtual image distance, without lengthening the optical path length L ₁ of the optical system, increasing the magnification of the optical system, increasing the optical unit However, there is a problem that the display image can be displayed farther, but the distortion and aberration of the display image are large and the image flows when the viewpoint is moved.

On the other hand, as an optical unit of Figure 3, without increasing the magnification of the optical system, when a large optical path length L ₁ of the optical system, the image flow problems when changing distortion of the display image, aberration, viewpoint However, the optical path is bent in the vertical plane, so the optical unit is too thick to be miniaturized and cannot be stored in the dashboard of an automobile. There was a problem.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lens optical system capable of downsizing an image display device such as a head-up display, and an image display device and a head-up display using the lens optical system. It is to provide.

In order to solve the above problems, in a lens optical system according to an aspect of the present invention, a first convex lens group in which a plurality of convex lenses are arranged in a planar shape and a plurality of convex lenses are arranged in a planar shape in order from the object side. A second convex lens group, and a third convex lens group in which a plurality of convex lenses are arranged in a planar shape. In order of the first convex lens group, the second convex lens group, and the third convex lens group, the lens diameter and lens pitch of the convex lens are larger, and the second convex lens group and the second convex lens group are larger than the distance between the first convex lens group and the second convex lens group. The distance from the triconvex lens group is increased.

According to this aspect, each first element convex lens constituting the first convex lens group that has received the light emitted radially from the object forms an inverted image of the object on the image plane of each first element convex lens. Each second element convex lens constituting the second convex lens group receives the light flux of each inverted image and bends the light flux in the direction of the main optical axis. Each third element convex lens constituting the third convex lens group receives each bent light beam and forms a virtual image of an unbroken object farther on the main optical axis than the optical path length from the viewpoint to the object. In addition, by making the distance between the second convex lens group and the third convex lens group longer than the distance between the first convex lens group and the second convex lens group, the light beam incident on the first convex lens group is the second convex lens. It is possible to prevent missing when passing through the group and the third convex lens group. Then, by adjusting the lens pitch of the third element convex lens of the third convex lens group, the radius of curvature, and the distance between the second convex lens group and the third convex lens group, the virtual image can be placed at an arbitrary position on the main optical axis. Can be formed. According to this aspect, it is possible to form a virtual image of an object at an arbitrary position without increasing the optical path length of the optical system as in the prior art described above, so that the size of an image display device such as a head-up display is reduced. it can. Here, the main optical axis is the optical axis of the lens optical system. Moreover, an object, a display, and an image display part are consent.

In the first convex lens group, the focal length of each first element convex lens may be set so that the imaging surface of each first element convex lens is positioned on the main plane of the corresponding second element convex lens. The lens pitch of the first element convex lens and the second element convex lens may not be the same in the first convex lens group and the second convex lens group, respectively. When all the lens pitches are the same in the first convex lens group, the lens pitch of the second element convex lens may be increased as the distance from the main optical axis increases. Further, when the lens pitch is all the same in the second convex lens group, the lens pitch of the first element convex lens may be decreased as the distance from the main optical axis increases. Here, when the lens pitch is not the same in the first convex lens group and / or the second convex lens group, the two adjacent first element convex lenses and second element convex lenses corresponding to each other in a one-to-one correspondence between the respective element convex lenses. As for the lens pitch, the lens pitch between the second element convex lenses is always larger than the lens pitch between the first element convex lenses.

According to this aspect, the inverted image of the object that has been formed on the first convex lens group side with respect to the main plane of the corresponding second element convex lens by the curvature of field of each first element convex lens so far is the second element convex lens. Located on the main plane. The focal length of each first element convex lens increases as the distance from the main optical axis increases. Each second element convex lens receives the light flux of each inverted image and bends it in the direction of the main optical axis. In the second convex lens group, it is easier to manufacture the lens optical system when the second element convex lenses are arranged on a plane. In this case, the lens pitch of the first element convex lens and / or the second element convex lens is first. It is not the same in the convex lens group and / or the second convex lens group.

According to this embodiment, since the area of the luminous flux of the inverted image of the object by each first element convex lens that can be bent by each second element convex lens increases, the virtual image of the object formed at an arbitrary position as described above can be widened. It will be visible from.

The first convex lens group may have a vertex surface that is concave with respect to the object. Here, the vertex surface is a quadric surface that is in contact with the vertex of each first element convex lens.

According to this form, compared with the case where the vertex surface is flat, the incident cross section with respect to the first element convex lens away from the main optical axis of the light beam emitted from the object can be increased, and the light beam emitted from the object enters. The number of first element convex lenses can be increased. According to this form, the virtual image of the object formed at an arbitrary position as described above can be brightened.

The focal length of the third convex lens group may be set so that the imaging plane of each third element convex lens is positioned on the main plane of the corresponding second element convex lens. In this case, the lens pitch of the third element convex lens and / or the second element convex lens is not the same in the third convex lens group and / or the second convex lens group, respectively.

According to this embodiment, the inverted image of the viewpoint that has been formed on the third convex lens group side with respect to the main plane of each second element lens corresponding to the curvature of field of each third element convex lens so far is represented by each second element. Located on the main plane of the convex lens. The focal length of each third element convex lens increases as the distance from the main optical axis increases. Each second element convex lens receives a light beam of an inverted image of an object by each first element convex lens. Therefore, the lens pitch of the third element convex lens and / or the second element convex lens is not the same in the third convex lens group and / or the second convex lens group, respectively.

In the third convex lens group, the vertex surface may be convex with respect to the object.

In this form, that is, when the surface in contact with the apex of each third element convex lens is convex with respect to the object, more light rays are emitted from the third element convex lens away from the main optical axis.

According to this embodiment, it becomes possible to visually recognize the virtual image of the object formed at an arbitrary position as described above without impairing the brightness. Here, the viewpoint refers to the eye, and the viewpoint position refers to the position of the eye. Both are located on the opposite side of the object across the lens optical system.

Furthermore, means for limiting the radiation angle of the light beam emitted from the image display unit for displaying the image may be provided.

According to this embodiment, the imaging range of the inverted image on the main plane of each second element convex lens by each first element convex lens can be limited. According to this aspect, even if an inverted image is formed on the first convex lens group side of the main plane of each second element convex lens by the field curvature of each first element convex lens, the range in which the virtual image of the object can be visually recognized is distorted. And can be limited to a range without blur.

A first lens array plate having a plurality of first outer convex lenses regularly arranged on one surface and a plurality of first inner convex lenses regularly arranged on the other surface; and regular on one surface A second lens array plate having a plurality of second outer convex lenses disposed on the other surface and a plurality of second inner convex lenses regularly disposed on the other surface, the first inner convex lens and the second inner convex lens. The first lens array plate and the second lens array plate are stacked such that the plurality of first outer convex lenses constitute a first convex lens group, and a plurality of first inner convex lenses and second inner convex lenses are formed. May constitute a second convex lens group, and a plurality of second outer convex lenses may constitute a third convex lens group. The radii of curvature of the first inner convex lens and the second inner convex lens may be equal, and the optical axes of the opposing lenses may be matched.

In this case, since the lens optical system described above can be configured by laminating two lens array plates, the lens optical system can have a simple structure, and the cost can be reduced. *

Another aspect of the present invention is an image display device. This apparatus includes an image display unit that displays an image, and the above-described lens optical system that receives light from the image display unit and displays a virtual image of the image.

According to this aspect, a small image display device can be configured. Such an image display device can be used for a game machine, for example. In other words, a three-dimensional effect of the game can be produced by forming a virtual image having a depth farther than the image displayed on the image display unit. *

Still another aspect of the present invention is a head-up display. One form of the head-up display includes an image display unit that displays an image, a lens optical system that receives light from the image display unit, and reflects light from the lens optical system toward the observer, And a combiner that displays a virtual image of the image in front of the. A mirror that changes the direction of light may be placed between the image display unit and the lens optical system, and between the lens optical system and the combiner.

According to these aspects, the optical unit in the head-up display can be reduced in size. This makes it possible to store the optical unit of the head-up display even when there is not enough space in the dashboard.

It should be noted that an arbitrary combination of the above-described components and a conversion of the expression of the present invention between a method, an apparatus, a system, and the like are also effective as an aspect of the present invention.

According to the present invention, it is possible to provide a lens optical system capable of downsizing an image display device such as a head-up display, and an image display device and a head-up display using the lens optical system.

It is a figure which shows an example of the conventional head-up display. It is a figure which shows explanatory drawing of the distant expansion display by a concave mirror. It is a figure which shows an example of another conventional optical unit. It is a figure for demonstrating the lens optical system which concerns on embodiment of this invention. It is sectional drawing of the lens optical system which concerns on this Embodiment. FIGS. 6A to 6C are diagrams for explaining the operation of the lens optical system according to the present embodiment. It is a figure for demonstrating the 3rd element convex lens which concerns on this Embodiment, and a light beam. FIG. 7A shows a case where T12 = T23, and FIG. 7B shows a case where T12 <T23. It is a figure for demonstrating the radiation angle limiting means which concerns on this Embodiment. It is a figure for demonstrating the effect of the focal distance adjustment of the 1st convex lens group which concerns on this Embodiment, and a lens vertex surface adjustment. It is a figure for demonstrating the head-up display using the lens optical system which concerns on this Embodiment. It is a figure for demonstrating the head-up display using the lens optical system which concerns on this Embodiment. It is a figure which shows the optical system of the 1st Example made as an experiment. It is a figure which shows the item of the lens optical system concerning a 1st Example. It is a figure which shows distribution of the focal distance of the 1st element convex lens which concerns on a 1st Example. It is a figure which shows the virtual image imaged with the camera which concerns on a 1st Example. As a comparative example of the first embodiment, it is a diagram showing the specifications of the lens optical system when the focal lengths of the first element convex lenses of the first convex lens group are all the same. In the 1st Example, it is the figure which showed the change of the virtual image visually recognized by the presence or absence of the focal distance adjustment of a 1st element convex lens. FIGS. 17A to 17C show virtual images captured by the camera when the focal length is adjusted and FIGS. 17D to 17F are not adjusted. In a 1st Example, it is the figure showing the result of the change of the virtual image visually recognized by the presence or absence of the focal distance adjustment of a 1st element convex lens. FIG. 19 is a diagram illustrating a relationship between an imaging position of a virtual image camera and an optical axis in the imaging of the virtual image illustrated in FIGS. 17 and 18. It is a figure which shows the optical system of the 2nd Example made as an experiment. It is a figure which shows the virtual image imaged with the camera which concerns on a 2nd Example.

10 lens optical system, 12 first lens array plate, 14 second lens array plate, 20 first convex lens group, 21 first element convex lens, 22 second convex lens group, 23 second element convex lens, 24 third convex lens group, 25 Third element convex lens, 30 image display section, 32 front window, 33 optical path change mirror, 34 combiner, 40 objects, 42 virtual images, 44 viewpoints, 52 images, 54 virtual images, 60 cameras, 62 landmarks, 100 head-up display.

FIG. 4 is a diagram for explaining the lens optical system 10 according to the embodiment of the present invention. As shown in FIG. 4, the lens optical system 10 has a structure in which a first lens array plate 12 and a second lens array plate 14 in which a plurality of convex lenses are formed on both surfaces are laminated. FIG. 4 shows a state in which a plurality of second outer convex lenses 14 a are arranged on the second outer surface 14 c of the second lens array plate 14.

The lens optical system 10 receives light from the object 40 located on the object side which is the first outer surface 12c side of the first lens array plate 12, and is on the second outer surface 14c side of the second lens array plate 14. A virtual image 42 is displayed at the viewpoint 44 of the observer located on the observation side. The virtual image 42 is formed farther than the optical path length from the observer's viewpoint 44 to the object 40. By using the lens optical system 10 according to the present embodiment, an image display device that displays a virtual image to an observer, such as a head-up display, can be configured.

FIG. 5 is a cross-sectional view of the lens optical system 10 according to the present embodiment. As described above, the lens optical system 10 has a structure in which the first lens array plate 12 having a plurality of convex lenses arranged on both surfaces and the second lens array plate 14 are laminated. That is, a plurality of first outer convex lenses 12a are regularly arranged on the first outer surface 12c which is one surface of the first lens array plate 12, and on the first inner surface 12d which is the other surface. The plurality of first inner convex lenses 12b are regularly arranged. A plurality of second outer convex lenses 14a are regularly arranged on the second outer surface 14c, which is one surface of the second lens array plate 14, and on the second inner surface 14d, which is the other surface. A plurality of second inner convex lenses 14b are regularly arranged. The first lens array plate 12 and the second lens array plate 14 are laminated so that the first inner convex lens 12b and the second inner convex lens 14b face each other.

On the first outer surface 12c, the first inner surface 12d, the second outer surface 14c, and the second inner surface 14d, the first outer convex lens 12a, the first inner convex lens 12b, the second outer convex lens 14a, and the second inner convex lens 14b are , Each arranged in a close packed arrangement. FIG. 4 shows a state in which the second outer convex lenses 14 a are arranged in a close-packed arrangement on the second outer surface 14 c of the second lens array plate 14.

In the present embodiment, the plurality of first outer convex lenses 12 a arranged in a plane form a first convex lens group 20. Hereinafter, the first outer convex lens 12a is appropriately referred to as a “first element convex lens 21”.

The first inner convex lens 12b and the second inner convex lens 14b arranged in a plane have the same lens diameter, and the first inner convex lens 12b and the second inner convex lens 14b facing each other have the same optical axis and are convex lenses. It arrange | positions so that surfaces may contact | abut. One set of the first inner convex lens 12b and the second inner convex lens 14b arranged in this manner functions as one convex lens. Therefore, in the following, a pair of the first inner convex lens 12b and the second inner convex lens 14b facing each other is appropriately treated as the “second element convex lens 23”. The plurality of second element convex lenses 23 constitute a second convex lens group 22.

Further, the plurality of second outer convex lenses 14 a arranged in a plane form a third convex lens group 24. Hereinafter, the second outer convex lens 14a is appropriately referred to as a “third element convex lens 25”.

Further, the distance between the first convex lens group 20 and the second convex lens group 22 arranged in a plane is referred to as T12, and the distance between the second convex lens group 22 and the third convex lens group 24 is referred to as T23.

In the present embodiment, the first convex lens group 20, the second convex lens group 22, and the third convex lens group 24 are configured so that the lens diameter and lens pitch of the convex lens increase in order, and the first convex lens group 20 and the second convex lens group 20 The distance between the second convex lens group 22 and the third convex lens group 24 is longer than the distance between the convex lens group 22.

That is, the lens diameter d ₁ of the first element convex lens 21 <the lens diameter d ₂ of the second element convex lens 23 <the lens diameter d ₃ of the third element convex lens 25, and the lens pitch p ₁ of the first element convex lens 21 <second. The lens pitch p ₂ of the element convex lens 23 <the lens pitch p ₃ of the third element convex lens 25, and T23> T12. In the present embodiment, the lens pitch is the distance between the centers of the two closest lenses. The lens diameter is a diameter of a circumscribed circle of a portion having a function as a lens.

Further, in the present embodiment, the first convex lens group 20 includes the individual first element convex lenses so that the image formation surface of each first element convex lens 21 is located on the main plane of each corresponding second element convex lens 23. 21 is provided with a distribution of focal lengths concentrically with respect to the main optical axis, and the second element convex lens 23 of the second convex lens group 22 passes through each first element convex lens 21 of the first convex lens group 20. It arrange | positions so that a light beam may be bent in the direction of a main optical axis.

FIG. 5 shows a case where the first element convex lenses 21 of the first convex lens group are arranged at a constant (same) lens pitch. In this case, the second element convex lens 23 and the third element convex lens 25 are arranged in each convex lens group. In the plane, the lenses are arranged so that the lens pitch increases as the distance from the main optical axis increases. In FIG. 5, the main plane of the second element convex lens 23 is a plane on which the contact point between the first inner convex lens 12b and the second inner convex lens 14b is located. In FIG. 5, the main planes of the second element convex lenses 23 are all located on the same plane.

When the lens pitches of the second element convex lens 23 and the third element convex lens 25 are not the same in the plane of each convex lens group, the corresponding first element convex lens 21, second element convex lens 23 and third element convex lens 25 are combined. , The lens pitch between the two adjacent element convex lenses is always the lens pitch P ₁ between the first element convex lenses <the lens pitch P ₂ between the second element convex lenses <the third element convex lenses the lens pitch _{P 3.}

In the present embodiment, the individual convex lenses 12a of the first convex lens group 20 are provided with apex surfaces that are concentric with respect to the main optical axis and concave with respect to the object.

The first lens array plate 12 and the second lens array plate 14 are formed by injection molding. The material of the first lens array plate 12 and the second lens array plate 14 is preferably one that can be used for injection molding, has high light transmittance with respect to light in a necessary wavelength band, and low water absorption. Examples of desirable materials include cycloolefin resins, olefin resins, norbornene resins, and polycarbonates.

6A to 6C are diagrams for explaining the operation of the lens optical system 10 according to the present embodiment. FIG. 6A shows that when the object 40 is observed with both eyes from a position separated by the distance D, the observer (viewpoint) 44 can visually recognize the object 40 at the position of the distance D.

Here, as shown in FIG. 6B, the first convex lens group 20 and the third convex lens group 24 having different lens diameters and lens pitches are arranged at a desired interval between the object 40 and the viewpoint 44 of the observer. The light from the object 40 is considered as being divided into light beams emitted from the first element convex lenses 21 of the first convex lens group 20. Here, the distance between the first convex lens group 20 and the third convex lens group 24 is such that the light beam radiated from the object 40 is emitted from the third convex lens group 24 without changing the angle, and the first convex lens group 20 is individually separated from the object 40. The first element convex lens 21 is determined so as to match the light beam angle.

In the case of the configuration as shown in FIG. 6B, each first element convex lens 21 of the first convex lens group 20 that has received the light emitted radially from the object 40 is inverted on the imaging surface of each first element convex lens 21. An image (also called an element image) is formed. Each third element convex lens 25 of the third convex lens group 24 receives each light flux of each element image and emits it toward the observer. When the observer observes such a radiation beam with both eyes, the object 40 can be visually recognized by being inverted from the observer's viewpoint 44 to the position of the distance D. *

Next, as shown in FIG. 6C, the lens diameter and the lens pitch are larger between the first convex lens group 20 and the third convex lens group 24 than the first convex lens group 20, and the lens diameter and the lens pitch are larger than those of the third convex lens group 24. The lens pitch is small, the distance between the second convex lens group 22 and the third convex lens group 24 is longer than the distance between the first convex lens group 20 and the second convex lens group 22, and the first convex lens group 20 and the third convex lens group. A second convex lens group 22 having a refractive power greater than 24 is added. As described above, each second element convex lens 23 of the second convex lens group 22 is arranged so that its main plane is located on the image plane of each first element convex lens 21.

Each second element convex lens 23 of the second convex lens group 22 bends each light flux contributing to the image formation of each element image in the optical axis direction of each second element convex lens 23. In this way, the light beam is bent by each second element convex lens 23 of the second convex lens group 22, so that the observer can observe an observation image that is a virtual image on the extension line of the main optical axis in the opposite direction from the viewpoint of the bent light beam. 42 can be seen. By adjusting the lens pitch and curvature radius of the third element convex lens 25 and the distance between the second convex lens group 22 and the third convex lens group 24, the observation image 42 can be formed at an arbitrary position D '. Of course, the magnification of the observation image 42 and the virtual image position D ′ can be changed by changing the distance E between the object 40 and the first convex lens group 20.

That is, a high-quality inverted image is formed by the first convex lens group 20, the lens pitch of the second element convex lens 23 and the third element convex lens 25, the radius of curvature, the distance between the second convex lens group 22 and the third convex lens group 24, And by adjusting the position and reading the inverted image, the virtual image 42 can be formed at an arbitrary position, and both the parallax and the diopter can be achieved. Here, the viewpoints of the observer and the observer, and the viewpoints are the same as 44, and the viewpoints refer to eyes.

Speaking of the distance T12 between the first convex lens group 20 and the second convex lens group 22 and the distance T23 between the second convex lens group 22 and the third convex lens group 24, the light flux passing through the first element convex lens 21 and the third element convex lens 25 is interrupted. In proportion to the area, T23> T12.

FIG. 7 is a diagram for explaining the light flux of the third element convex lens 25 in the third convex lens group 24 according to the present embodiment. FIG. 7A shows the spread of the light beam of the lens optical system when T23 = T12, and FIG. 7B shows the spread of the light beam of the lens optical system when T23> T12. As shown in FIG. 7A, when T23 = T12, the light beams emitted from the third convex lens group toward the observer are discrete and open, whereas FIG. As shown in FIG. 4, it is understood that the light beam emitted from the third convex lens group toward the observer becomes continuous by setting T23> T12. When the luminous flux becomes discrete, the virtual image 54 becomes difficult to see with the collection of point-like objects, whereas by making the luminous flux continuous, a smooth, easy-to-view virtual image can be obtained.

FIG. 8 is a view for explaining the radiation angle limiting means according to the present embodiment. As shown in FIG. 8A, by providing means F for limiting the radiation angle of the light beam emitted from the object 40, each of the second convex lens groups 22 by the first element convex lenses 21 of the first convex lens group 20 is provided. The range in which the inverted image is formed on the plane 13 connecting the main planes of the two-element convex lens 23 can be limited. According to this embodiment, there is a curvature of field of each first element convex lens 21 of the first convex lens group 20, and the first convex lens is more than the plane 13 connecting the main planes of the second element convex lenses 23 of the second convex lens group 22. Even if an inverted image is formed on the group side (the surface connecting the imaging surfaces of the first element convex lenses 21 is the surface 71), the virtual image of the object formed at an arbitrary position can be visually recognized without distortion or blurring. . The radiation angle limiting means regulates the spread of light rays emitted from the object (image display unit). In other words, the range in which the virtual image can be seen is limited. In the case of the image display unit 30 that displays the object 40 using the point light source 36 other than the visual field limiting plate F, for example, When the lens 65 is installed on the optical path, the lens 65 corresponds to the radiation angle limiting means.

FIG. 9 is a diagram for explaining the imaging plane, main plane, focal length distribution, and apex plane of the lens optical system 10 according to the present embodiment.

As shown in FIG. 9A, the surface 71 connecting the imaging surfaces of the first element convex lenses 21, which is based on the positional relationship between the object 40 and the first element convex lenses 21, is the image plane of each first element convex lens 21. The plane connecting the main planes of the second element convex lenses 23 because it is positioned closer to the first convex lens group 20 than the plane 13 connecting the main planes of the second element convex lenses 23 as it moves away from the main optical axis 72 due to curvature. At position 13, the inverted image is blurred.

As described above, when the focal lengths of the individual first element convex lenses 21 are adjusted so as to be positioned on the surface 13 connecting the principal planes of the second element convex lenses 23, the imaging surfaces of the first element convex lenses 21 and the second Since the principal planes of the element convex lenses 23 coincide with each other over a wide range, a good virtual image can be observed from a wide range of viewpoints (FIG. 9B).

Also, as shown in FIG. 9B, the surface in contact with the apex of each first element convex lens 21 is formed concave on the object side with respect to the main optical axis 72. That is, by increasing the lens height of the first element convex lens 21 so as to be concentric with the main optical axis 72 and concave on the object 40 side, the light beam that can be incident on the convex lens away from the main optical axis 72. The virtual image of the object 40 formed at an arbitrary position can be viewed brightly without depending on the position of the viewpoint.

In the above description, the adjustment of the focal length of the radiation angle limiting means F and the first element convex lens is described separately, but these may be used separately or in combination.

As described above, according to the lens optical system 10 according to the present embodiment, the virtual image 42 of the object 40 can be formed at an arbitrary position without increasing the distance E between the object 40 and the first convex lens group 20. Therefore, an image display device such as a head-up display can be downsized.

FIG. 10 is a diagram for explaining the first head-up display 100 using the lens optical system 10 according to the present embodiment. The head-up display 100 includes an image display unit 30, the above-described lens optical system 10, and a combiner 34. The lens optical system 10 and the image display unit 30 constitute an optical unit of the head-up display 100, and are housed, for example, in a dashboard of a vehicle.

The image display unit 30 is configured by a liquid crystal display, for example, and displays information such as the vehicle speed and the remaining amount of fuel as an image 52 based on a signal from an image processing unit (not shown).

The lens optical system 10 is arranged so that the first outer surface 12 c of the first lens array plate 12 faces the surface of the image display unit 30. The light emitted from the image display unit 30 enters the first convex lens group 20, then passes through the second convex lens group 22 and is emitted from the third convex lens group 24. The lens optical system 10 is arranged so that light emitted from the third convex lens group 24 enters the front window 32 at a predetermined incident angle, for example, an incident angle of 45 degrees.

The combiner 34 is a reflective film formed on the surface of the front window 32, and reflects the light emitted from the lens optical system 10 toward the driver (viewpoint) 44. The driver can visually recognize the virtual image 54 of the image 52 on the extension line of the optical path from the viewpoint to the combiner 34. *

Here, the distance from the image display unit 30 to the first convex lens group 20 of the lens optical system 10 is D1, the distance from the third convex lens group 24 of the lens optical system 10 to the combiner 34 is D2, and the viewpoint of the driver from the combiner 34 is shown. The distance to 44 is D3, and the distance from the combiner 34 to the virtual image 54 is D4. At this time, the optical path length from the driver's viewpoint 44 to the image 52 is D1 + D2 + D3. The optical path length from the driver's viewpoint 44 to the virtual image 54 is D3 + D4. In the lens optical system 10 according to the present embodiment, the optical path length D3 + D4 from the driver's viewpoint 44 to the virtual image 54 and the optical path length D1 + D2 + D3 from the driver's viewpoint 44 to the image 52 are the same as described in FIG. Can be longer.

It is preferable that the virtual image 54 is formed as far as possible in front of the vehicle so that the driver's viewpoint 44 can be seen by superimposing the landscape and the virtual image 54 in front of the vehicle. For example, it is desirable to secure a distance D4 from the combiner 34 to the virtual image 54 of about 1 m. In the optical unit of the conventional head-up display as shown in FIG. 3, in order to secure 1 m from the combiner to the virtual image, it is necessary to secure 1 m of the optical path length from the image to the concave mirror. In this case, it is difficult to reduce the size of the optical unit. However, the distance D1 + D2 can be made smaller than the distance D4 by configuring the head-up display 100 using the lens optical system 10 according to the present embodiment. Therefore, it is not necessary to secure a very long optical path length in the optical unit, and the optical unit can be downsized.

FIG. 11 is a diagram for explaining a second head-up display 200 using the lens optical system 10 according to the present embodiment. The head-up display 200 includes an image display unit 30, the above-described lens optical system 10, an optical path changing mirror 33, and a combiner 34. The lens optical system 10, the image display unit 30, and the optical path changing mirror 33 constitute an optical unit of the head-up display 200, and are housed, for example, in a dashboard of a vehicle.

The lens optical system 10 is arranged so that the first outer surface 12 c of the first lens array plate 12 faces the surface of the image display unit 30. The light emitted from the image display unit 30 enters the first convex lens group 20, then passes through the second convex lens group 22 and is emitted from the third convex lens group 24. The lens optical system 10 is disposed so that light emitted from the third convex lens group 24 is reflected by the optical path changing mirror 33 and is incident on the front window 32 at a predetermined incident angle, for example, an incident angle of 45 degrees.

The combiner 34 is a reflective film formed on the surface of the front window 32, and reflects the light emitted from the lens optical system 10 toward the driver. The driver can visually recognize the virtual image 54 of the image 52 on the extension line of the optical path from the viewpoint 44 to the combiner 34.

Here, the distance from the image display unit 30 to the first convex lens group 20 of the lens optical system 10 is D1, the distance from the third convex lens group 24 of the lens optical system 10 to the optical path changing mirror 33 is D5, and from the optical path changing mirror 33. The distance to the combiner 34 is D6, the distance from the combiner 34 to the driver's viewpoint 44 is D3, and the distance from the combiner 34 to the virtual image 54 is D4. At this time, the optical path length from the driver's viewpoint 44 to the image 52 is D1 + D5 + D6 + D3. The optical path length from the driver's viewpoint 44 to the virtual image 54 is D3 + D4. In the lens optical system 10 according to the present embodiment, the optical path length D3 + D4 from the driver's viewpoint 44 to the virtual image 54 and the optical path length D1 + D5 + D6 + D3 from the driver's viewpoint 44 to the image 52 are the same as described in FIG. Can be longer.

It is preferable that the virtual image 54 is formed as far as possible in front of the vehicle so that the driver's viewpoint 44 can be seen by superimposing the landscape and the virtual image 54 in front of the vehicle. For example, it is desirable to secure a distance D4 from the combiner 34 to the virtual image 54 of about 1 m. In the optical unit of the conventional head-up display as shown in FIG. 3, in order to secure 1 m from the combiner to the virtual image, it is necessary to secure 1 m of the optical path length from the image to the concave mirror. In this case, it is difficult to reduce the size of the optical unit. However, the distance D1 + D5 + D6 can be made smaller than the distance D4 by configuring the head-up display 200 using the lens optical system 10 according to the present embodiment.

According to the head-up display 200, it is considered that only the optical path changing mirror 33 is added between the lens optical system 10 of the head-up display 100 and the combiner 34. By adding this mirror, the height of the head-up display 200 is increased. Can be lower.

Further, according to the head-up

displays

100 and 200 according to the present embodiment, the virtual image 54 of the image 52 displayed on the image display unit 30 can be displayed far away with a very simple configuration. As a device for forming an image with a sense of depth, a lenticular screen is conventionally arranged at the image forming position of the video projection system, and images including binocular parallax are spatially separated and presented to the left and right eyes, respectively. There is a device. However, in such an apparatus, the left and right images including the binocular parallax are synthesized in the observer's head to obtain a sense of depth, so that it is not easy to recognize an image with a sense of depth. It will accompany. However, in the head-up

displays

100 and 200 according to the present embodiment, it is not necessary to synthesize the left and right images including binocular parallax in the observer's head, and the virtual image 54 having a sense of depth can be easily obtained. Therefore, the observer will not feel tired.

Next, a first example in which the head-up display 100 according to the present embodiment is actually prototyped will be described. FIG. 12 is a diagram showing an optical system of a first example in which the head-up display 100 is prototyped. FIG. 13 is a diagram showing specifications of the lens optical system 10 used in the first embodiment. In the first embodiment, the camera 60 is placed at the position of the viewpoint 44 in FIG. 10, and the mark 62 is placed at the position where the virtual image 52 is formed.

As shown in FIG. 12, in the first embodiment, the distance D1 from the image display unit 30 to the first convex lens group 20 is 130 mm, the distance D2 from the third convex lens group 24 to the combiner 34 is 100 mm, and from the combiner 34. The distance D3 to the camera 60 was set to 1000 mm, and the distance D4 from the combiner 34 to the mark 62 was set to 1000 mm.

Further, as shown in FIG. 13, the first element convex lens 21 was set such that the radius of curvature was 0.584 to 0.681 mm (changed depending on the focal length) and the lens pitch was 0.662 mm. Here, the focal length distribution of each first element convex lens 21 is set as shown in FIG. The focal length of each first element convex lens 21 increases concentrically as the distance from the main optical axis 72 (not shown) increases. The curvature radius of the first inner convex lens 12b and the second inner convex lens 14b constituting the second convex lens group 22 was 0.497 mm, and the lens pitch was increased from 0.665 mm to 0.666 mm as the distance from the main optical axis was increased. The third element convex lens 25 had a radius of curvature of 1.042 mm, and the lens pitch was increased from 0.667 mm to 0.668 mm with increasing distance from the main optical axis. The thickness of the first lens array plate 12 was set to 1.405 mm, and the thickness of the second lens array plate 14 was set to 2.999 mm. In addition, the refractive index of all the lenses is 1.56.

In the first embodiment configured as described above, a character “180 Km / h” having a diagonal size of 1 inch was displayed on the image display unit 30, and a virtual image formed by the camera 60 was captured. FIG. 15 is a diagram illustrating a virtual image 54 captured by the camera 60. As shown in FIG. 15, it can be seen that a virtual image 54 can be formed at the position where the mark 62 is installed. The size of the virtual image was enlarged to about three times that of the original image 52.

Thus, even if the distance D1 from the image display unit 30 to the first convex lens group 20 is shortened to 130 mm and the distance D2 from the third convex lens group 24 to the combiner is shortened to 100 mm, the distance from the combiner 34 is reduced. It has been found that a virtual image 54 having parallax and diopter can be displayed at a position of D4 = 1000 mm, and the optical unit of the head-up display 100 can be made compact and low-cost.

FIG. 16 shows the specifications of the lens optical system when the focal length of the first element convex lens 21 is the same in the first convex lens group 20 as a comparative example to the first embodiment. The first outer convex lens 12a constituting the first convex lens group 20 has a radius of curvature = 0.584 mm and the lens pitch = 0.662 mm, and the first inner convex lens 12b and the second inner convex lens 14b constituting the second convex lens group 22 are The radius of curvature = 0.497 mm and the lens pitch = 0.665 mm, and the second outer convex lens 14 a constituting the third convex lens group 24 was set to have a radius of curvature = 1.42 mm and a lens pitch = 0.668 mm. The thickness of the first lens array plate 12 was set to 1.405 mm, and the thickness of the second lens array plate 14 was set to 2.999 mm. The refractive index of the lens is 1.56 for all convex lenses. In FIG. 16, the focal length of each first element convex lens 21 is the same in the first convex lens group, and the lens pitch of the second element convex lens 23 and the third element convex lens 25 is the same in each convex lens group. .

FIG. 17 shows the results of observing how the virtual image looks different when the focal length distribution is attached to the first element convex lens 21 (first embodiment) and when it is not attached (comparative example). Show. 17, as shown in FIG. 19, (1) the position of the camera in FIG. 12, that is, the optical axis 74 (the light traveling along the main optical axis 72 of the lens optical system 72 is combined with the combiner 34). (2) a position 30 mm away from the position (1) of the optical axis 74 in a direction perpendicular to the optical axis 74 (lateral direction to the front window), (3) ) A position 60 mm away from the optical axis 74 in the vertical direction.

In FIG. 17, FIGS. 17A to 17C show the results in the case where the first element convex lens 21 is provided with a focal length distribution (Example), and FIGS. 17D to 17F show the focus. The results are shown when no distance distribution is provided (comparative example). (A) and (d) are the positions of (1), (b) and (e) are the positions of (2), and (c) and (f) are the results of imaging at the positions of (3). Indicates.

FIG. 18 summarizes the observation results of FIG. When the focal length distribution is provided, the virtual image 54 can be clearly seen even if it is 60 mm away from the optical axis 74 (indicated by a circle), whereas when the focal length of the first element convex lens 21 is all constant, the optical axis 74 is obtained. It can be seen that the virtual image 54 is already out of focus (indicated by Δ) when the distance is 30 mm away, and that it is difficult to visually recognize (indicated by ×) when the distance is 60 mm away.

Each first element convex lens 21 is provided with a focal length distribution so that the imaging plane of each first element convex lens 21 constituting the first convex lens group 20 is located on the main plane of each corresponding second element convex lens 23. Accordingly, by adjusting the lens pitch of the second element convex lens 23 and the third element convex lens 25, the virtual image 54 can be viewed even at a position away from the optical axis 74. Therefore, the viewing area of the head-up display 100 can be expanded.

FIG. 20 is a diagram showing an optical system of a second example in which the head-up display 200 is prototyped. In the second embodiment, the camera 60 is placed at the position of the viewpoint 44 in FIG. 11, and the mark 62 is placed at the position where the virtual image 54 is formed.

As shown in FIG. 20, in the second embodiment, the distance D1 from the image display unit 30 to the first convex lens group 20 is 130 mm, the distance D5 from the third convex lens group 24 to the optical path changing mirror 33 is 50 mm, and the optical path. The distance D6 from the change mirror 33 to the combiner 34 was set to 100 mm, the distance D3 from the combiner 34 to the camera 60 was set to 1000 mm, and the distance D4 from the combiner 34 to the mark 62 was set to 1000 mm.

In the second embodiment configured as described above, a character “180 Km / h” having a diagonal size of 1 inch is displayed on the image display unit 30, and a virtual image 54 formed by the camera 60 is captured. FIG. 21 is a diagram illustrating a virtual image 54 captured by the camera 60. As shown in FIG. 21, it can be seen that the virtual image 54 is formed at the position where the mark 62 is provided even when the optical path changing mirror 33 is provided.

In the second embodiment, since the distance from the lens optical system 10 to the combiner 34 is increased by 50 mm compared to the first embodiment shown in FIG. 12, the size of the virtual image is slightly reduced, and the magnification is It was about 2.8 times.

As shown in the second embodiment, by using the optical path changing mirror 33, the distance D1 = 130 mm from the image display section 30 of the first embodiment that determines the height of the optical unit to the first convex lens group 20 is as follows. 230 mm obtained by adding a distance D2 = 100 mm from the third convex lens group 24 to the combiner is half of the width W (about 60 mm) of the lens optical system 10 and the optical path changing mirror 33 and the combiner 34 in the second embodiment. The distance D6 was shortened to 130 mm by adding 100 mm, and thus the height of the head-up display 200 could be made lower than that of the head-up display 100.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

The present invention can be used for a head-up display that displays information such as the vehicle speed in front of the front window of the vehicle.

Claims

In order from the object side, a first convex lens group in which a plurality of convex lenses are arranged in a plane, a second convex lens group in which a plurality of convex lenses are arranged in a plane, and a third convex lens in which a plurality of convex lenses are arranged in a plane. A group,
A lens optical system configured such that a lens diameter and a lens pitch of the convex lens increase in the order of the first convex lens group, the second convex lens group, and the third convex lens group;
A lens configured such that a distance between the second convex lens group and the third convex lens group is longer than a distance between the first convex lens group and the second convex lens group. Optical system.
The first element convex lens constituting the first convex lens group and the second element convex lens constituting the second convex lens group have a one-to-one correspondence, and the imaging surface of the first element convex lens corresponds to the first convex lens. 2. The lens optical system according to claim 1, wherein a focal length of the first element convex lens is set so as to be positioned on a main plane of the second element convex lens.
3. The lens optical system according to claim 1, wherein the lens pitch of the second element convex lens increases as the distance from the main optical axis increases.
3. The lens optical system according to claim 1, wherein the lens pitch of the first element convex lens decreases as the distance from the main optical axis increases.
The third element convex lens constituting the third convex lens group and the second element convex lens constituting the second convex lens group have a one-to-one correspondence, and the imaging plane of the third element convex lens corresponds to the first convex lens. 5. The lens optical system according to claim 1, wherein a focal length of the third element convex lens is set so as to be positioned on a main plane of the second element convex lens.
A first lens array plate having a plurality of first outer convex lenses regularly arranged on one surface and a plurality of first inner convex lenses regularly arranged on the other surface;
A second lens array plate having a plurality of second outer convex lenses regularly arranged on one surface and a plurality of second inner convex lenses regularly arranged on the other surface;
The first lens array plate and the second lens array plate are laminated so that the first inner convex lens and the second inner convex lens face each other,
The plurality of first outer convex lenses constitute the first convex lens group, the plurality of sets of the first inner convex lens and the second inner convex lens constitute the second convex lens group, and the plurality of second outer convex lenses. The lens optical system according to claim 1, wherein the third convex lens group is configured.
The first inner convex lens and the second inner convex lens have the same lens diameter, and the optical axes of the first inner convex lens and the second inner convex lens facing each other coincide with each other. Lens optical system
An image display unit for displaying an image;
The lens optical system according to claim 1, which receives light from the image display unit and displays a virtual image of the image.
An image display device comprising:
9. The image display device according to claim 8, wherein the image display unit for displaying an image is provided with means for limiting an emission angle of a light beam to be emitted.
An image display unit for displaying an image;
The lens optical system according to any one of claims 1 to 7, which receives light from the image display unit, and reflects light from the lens optical system toward an observer so that the image is displayed in front of the observer. A combiner displaying a virtual image;
A head-up display comprising:
An image display unit for displaying an image;
The lens optical system according to any one of claims 1 to 7 that receives light from the image display unit, and a mirror that reflects light from the lens optical system toward a combiner,
The combiner that reflects light from the mirror toward the viewer and displays a virtual image of the image in front of the viewer;
A head-up display comprising:
The head-up display according to claim 10 or 11, wherein the image display unit for displaying an image is provided with means for limiting an emission angle of a light beam to be emitted.