JP2007094394A - Optical system for head-up display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a head up display (HUD) which is miniaturized without using concave mirrors and is capable of varying the magnification of a display image by a simple configuration. <P>SOLUTION: In the HUD which reflects the display image projected from a display device 11, by a combiner 17 as a reflecting means and makes an observer visually recognize a reflection image from the combiner, a condenser lens set 13 for varying the magnification of the display image is provided on an optical path between the display device 11 and the combiner 17. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a head-up display optical system applicable to a vehicle such as an automobile.

  A head-up display (hereinafter referred to as “HUD”) reflects a display image from a display device provided in front of a driver's seat of an automobile or the like to a combiner incorporated in a reflecting means such as a windshield or a windshield. Thus, the information is superimposed on the front view or the foreground in the vicinity thereof so that the driver or the like can read information without moving the viewpoint from the driving state.

For example, as shown in FIG. 5, the HUD 100 is configured using a part of the inner surface of the windshield WS and functions as a half mirror, a concave mirror 103, a plane mirror 104, and a display 105 that projects image display image light. It consists of and.
In such a HUD 100, image display light is projected from the display unit 105, and the virtual image 106 is observed in front of the windshield WS at the position of the viewpoint 101 via the concave mirror 103, the optical system of the combination of the plane mirror 104 and the combiner 102. (For example, refer to Patent Document 1).

JP 2000-347127 A

  In general, in order to enlarge the virtual image 106 formed in front of the combiner 102 as much as possible, it is desirable to increase the magnification of the concave mirror 103 as much as possible. However, there is a limit to increasing the magnification ratio of the concave mirror 103. If the magnification ratio is too large, there is a problem that the virtual image 106 is significantly distorted. Therefore, in the HUD 100 shown in Patent Document 1, distortion is suppressed by using an optical system that is a combination of the concave mirror 103, the reflecting mirror 104, and the combiner 102. However, a plurality of optical elements must be used, and the HUD 100 increases in size. There is a problem of becoming.

  Furthermore, since the optical system is a combination of the concave mirror 103, the reflecting mirror 104, and the combiner 102, it is difficult to easily change the size of the virtual image 106, and when changing, the optical system must be redesigned. There is also a problem that costs increase.

  Accordingly, in view of the above-described problems of the prior art, the present invention provides a HUD optical system capable of reducing the size without using a concave mirror and changing the display image with a simple configuration. There is.

  In order to solve the above problems, in the present invention, in the HUD in which a display image displayed on a display device is projected toward a reflection means, and an observer visually recognizes the reflection image of the reflection means, the display device and the reflection In the optical path between the means, a condensing lens group for changing the display image is provided.

According to the present invention, the HUD is provided with the condenser lens group for changing the magnification of the display image in the optical path between the display device and the reflection means, so that the reflection means can be used without using a concave mirror as in the prior art. Can be irradiated. For this reason, HUD can be reduced in size by omitting a concave mirror.
Further, since the condenser lens set is provided in the optical path between the display device and the reflecting means, the magnification of the display image can be changed by changing the focal length of the condenser lens set to be inserted. .

Further, the magnification of the display image can be changed by changing the position of the condenser lens set to be inserted, that is, the distance from the display device or the reflecting means.
For this reason, the magnification of the display image can be easily changed by changing the focal length or the arrangement position of the condenser lens set to be inserted.

In the present invention, it is preferable that the condensing lens group is provided with a moving means that can move in the optical axis direction.
According to the present invention, since the condenser lens group is provided with a moving means, the condenser lens group can be freely moved in the optical axis direction, and the magnification can be easily changed. In other words, a zoom effect can be obtained without using a zoom lens.

In the present invention, it is preferable that the condenser lens group includes a lens having a positive refractive power and a lens having a negative refractive power for correcting chromatic aberration.
Thereby, chromatic aberration can be corrected with a simple lens configuration in which two lenses are combined.

In the present invention, it is preferable that a beam expander formed by combining a plurality of condensing lenses having different refractive powers is provided.
According to the present invention, the position in the optical axis direction where the display image (virtual image) can be seen can be adjusted by adjusting the interval between the condenser lenses having different refractive powers constituting the beam expander.

In the present invention, it is preferable that one of the condensing lens sets is a lens set having a negative refractive power and the other is a lens set having a positive refractive power.
According to the present invention, since the lens group having a negative refractive power and the lens group having a positive refractive power are combined, it is possible to shorten the distance between the condenser lens groups without forming an image. The overall system length can be shortened.

  In the present invention, in a HUD in which a display image displayed on the display device is projected toward the reflecting means, and an observer visually recognizes the reflected image from the reflecting means, in the optical path between the display device and the windshield. And a condensing lens for scaling the display image.

According to the present invention, since the HUD includes the condensing lens for scaling the display image in the optical path between the display device and the reflecting means, the reflecting means can be irradiated without using a concave mirror. it can. For this reason, HUD can be reduced in size by omitting a concave mirror.
Furthermore, since the condenser lens is provided in the optical path between the display device and the reflecting means, the magnification of the display image can be changed by changing the focal length of the condenser lens to be inserted.

Further, the magnification of the display image can be changed by changing the position of the condenser lens to be inserted, that is, the distance from the display device or the reflecting means.
For this reason, the magnification of the display image can be easily changed by changing the focal length or the arrangement position of the condenser lens to be inserted.

  Hereinafter, embodiments of an optical system for HUD according to the present invention will be described with reference to the drawings.

(overall structure)
FIG. 1 is a conceptual diagram showing a HUD according to the present invention.
As shown in FIG. 1, the HUD optical system 10 is housed in a dashboard provided below a windshield 16 in an automobile. The HUD optical system 10 constituting the HUD includes a display device 11 and a condensing lens set 13 capable of scaling the display image (virtual image 18) to enlarge or reduce. Further, in the present embodiment, a combiner 17 as a reflecting means is disposed at a predetermined location on the inner side surface of the windshield 16.

  The display device 11 includes at least a light source and a display body that displays information necessary for operation, and generates display information as light. Although not shown in the drawing, the display device 11 forms display information. A liquid crystal panel as a body and a backlight as a projection light source are provided. The display body is not limited to the liquid crystal panel, and may be, for example, an EL display, a CRT, a hot cathode tube, a fluorescent display tube, or the like. Information necessary for driving includes a traveling speed, an engine speed, a traveling distance, a remaining amount of fuel, a warning, a map, a time, and the like.

The condenser lens set 13 includes a lens 14 having a positive refractive power and a lens 15 having a negative refractive power that corrects chromatic aberration, and forms a projected light beam that forms a display image projected from the display device 11. To focus.
The lens 14 may not be a biconvex lens, and may be a lens such as a planoconvex lens or a convex meniscus lens.

The lens 15 having a negative refractive power is bonded to the display device 11 side of the lens 14 having a positive refractive power so as to correct chromatic aberration.
Further, there is no particular limitation on the direction in which the lens having negative refractive power and the lens having positive refractive power are combined, and a lens surface of a lens having positive refractive power and a lens having negative refractive power may be appropriately combined. Is possible.
The lens 14 having positive refractive power and the lens 15 having negative refractive power constituting the condenser lens group 13 are made of different types of materials. For example, the lens 13 having a positive refractive power is molded from crown glass or a transparent resin material having a small refractive index variation depending on the wavelength, and the lens 14 having a negative refractive power is made from flint glass or a transparent resin material having a large material dispersion. I am trying to mold. Note that other glass or transparent resin material may be used for bonding.

  Further, in the present embodiment, the lens 14 having a positive refractive power and the lens 15 having a negative refractive power are bonded together, but the present invention is not limited to this, and the lens 14 having a positive refractive power and You may arrange | position the lens 15 which has negative refractive power at fixed intervals.

  Furthermore, in the present embodiment, moving means 20 is provided that can move the condenser lens set 13 in the optical axis direction. The moving means 20 includes a motor 21, a feed screw 22 that is rotationally driven by the motor 21, and a rack 23 that moves the condensing lens set 13 in the optical axis direction by moving with the rotation of the feed screw 22. It has. Although not shown, a control circuit for controlling the motor 21 is provided.

The combiner 17 as a reflecting means functions as a half mirror, and displays an incident display image as a virtual image 18 in front of the windshield 16. That is, the combiner 17 is provided in order to increase the reflectance of the display image, and may be incident on the windshield 16 without providing the combiner 17. In this case, the windshield 16 functions as a reflecting means.
Moreover, in this Embodiment, although the combiner 17 also has a function as a half mirror, it is not limited to this, You may use the hologram which has a diffraction function.

  The light emitted from the display device 11 is reflected by the combiner 17 after passing through the condenser lens group 13 arranged so as to face the display device 11. For example, if a prism (not shown) or a reflecting mirror (not shown) is arranged between the display device 11 and the condenser lens set 13, a reflecting means such as a prism or a reflecting mirror can be used even if the orientation of the display device 11 is changed. Thus, the optical axis can be bent and incident on the condenser lens set 13. Further, a reflecting means such as a prism or a reflecting mirror may be disposed between the condenser lens set 13 and the combiner 17. In this case, the light transmitted through the condenser lens set 13 can be bent in an appropriate direction by the reflecting means and incident on the combiner 17.

Next, the operation of the HUD optical system will be described.
A projected light beam forming a display image projected from the display device 11 is converged by the condenser lens set 13 and enters the combiner 17. The display image reflected by the combiner 17 is projected on the viewpoint 12 side of the driver. The driver can view the display light beam as if a display image of the display device 11 is formed at a predetermined position in front of the windshield 16 by the projected light flux.

Further, in the present embodiment, the size of the display image is obtained by moving the condenser lens group 13 on the optical path between the display device 11 and the combiner 17 (or the windshield 16) using the moving unit 20. Can be changed.
Specifically, when the condensing lens set 13 is moved closer to the dotted line position, that is, the display device 11 side from the position of the solid line in FIG. 1, the driver as an observer displays a reduced display image (virtual image). 18) can be seen. Further, when it is desired to enlarge the display image (virtual image 18), the condenser lens set 13 may be brought closer to the observer side. In addition, you may make it move manually, without providing the moving means 20. FIG.

(Main effects of this embodiment)
Since the HUD optical system 10 includes the condensing lens set 13 for changing the display image in the optical path between the display device 11 and the combiner 17 as the reflecting means, a concave mirror is used as in the prior art. Irrespectively, the combiner 17 can be irradiated. For this reason, HUD can be reduced in size by omitting a concave mirror.
Furthermore, since the condenser lens set 13 is provided in the optical path between the display device 11 and the combiner 17, the magnification of the display image (virtual image 18) is changed by changing the focal length of the condenser lens set 13 to be inserted. Can be made.

Further, the position of the condenser lens set 13 to be inserted using the moving means 20, that is, the distance from the display device 11 or the reflecting means can be changed, and the magnification of the display image (virtual image 18) can be easily changed. Can do.
For this reason, the magnification of the display image (virtual image 18) can be easily changed by changing the focal length or the arrangement position of the condenser lens set 13 to be inserted.

  Further, in the HUD optical system 10, since the condenser lens group 13 is provided with the moving means 20, the condenser lens group 13 can be freely moved in the optical axis direction, and the magnification can be easily changed. be able to. In other words, a zoom effect can be obtained without using a zoom lens.

  In the HUD optical system 10, the condenser lens group 13 is a combination of a lens 14 having a positive refractive power and a lens 15 having a negative refractive power for correcting chromatic aberration. Thereby, chromatic aberration can be corrected with a simple lens configuration in which two lenses 14 and 15 are combined.

(Other embodiments)
The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited to this, and various modifications can be made without departing from the gist of the present invention.
For example, a second embodiment will be described with reference to FIG. FIG. 2 is a schematic configuration diagram illustrating an embodiment of the beam expander. Similarly, a third embodiment will be described with reference to FIG. 3, and a fourth embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected and demonstrated to the same member.

In the second embodiment shown in FIG. 2, the beam expander 30 is formed by combining, for example, two condensing lens groups 31 and 32 having different refractive powers.
The configuration is well known, but in brief, for example, an incident lens set 31 having a positive refractive power and a focal length f1 and an output lens set 32 having a positive refractive power and a focal length f2 are provided. The rear focal position of the lens group 31 and the front focal position of the outgoing lens group 32 are arranged so as to coincide with each other. With this configuration, when light having a beam diameter φDf1 is incident on the incident lens set 31, light having a beam diameter φDf2 is emitted from the output lens set 32.

The incident lens group 31 includes a lens 34 having a negative refractive power and a lens 33 having a positive refractive power, and the output lens group 32 includes a lens 36 having a negative refractive power and a positive refractive power. And a lens 35 having the above structure. In addition, the incident lens group 31 and the outgoing lens group 32 have positive refractive power. In the second embodiment, the convex surfaces of the incident lens group 31 and the outgoing lens group 32 are directed in the light traveling direction L.
As described above, in the HUD 10 shown in FIG. 1, the beam expander 30 is arranged instead of the condenser lens set 13 on the optical path between the display device 11 and the combiner 15, thereby changing the magnification to a predetermined size. The driver can view the displayed image (virtual image 18).

FIG. 3 is a schematic configuration diagram illustrating a beam expander 30A according to the third embodiment.
In the third embodiment shown in FIG. 3, the positions of the lens 34 having a positive refractive power and the lens 35 having a negative refractive power attached to the incident lens set 31 shown in the second embodiment are light-transmitted. In the traveling direction L. The arrangement of the lenses of the exit lens set 32 is the same as in the second embodiment.
Further, the entrance lens group 31 and the exit lens group 32 have positive refractive power, respectively.
According to this configuration, since each optical surface of the incident lens set 31 acts effectively compared to the second embodiment, the spherical aberration is reduced and the image is sharpened.

Next, FIG. 4 is a schematic configuration diagram for explaining a beam expander 30B according to the fourth embodiment. In the fourth embodiment shown in FIG. 4, the beam expander 30B is formed by combining condensing lens groups 31B and 32 having different refractive powers.
For example, an incident lens set 31B having a negative refractive power and a focal length f1 and an output lens set 32 having a positive refractive power f2 are provided, and the rear focal position and the outgoing lens set of the incident lens set 31B are provided. It arrange | positions so that 32 front side focus positions may correspond. With this configuration, when light having a beam diameter φDf1 is incident on the incident lens set 31B, light having a beam diameter φDf2 is emitted from the output lens set 32.
In addition, the lens 33B having a negative refractive power is attached to the incident lens set 31B with respect to the lens 34B having a positive refractive power, and has a negative refractive power as a whole. In addition, a lens 36 having a negative refractive power is attached to the lens 35 having a positive refractive power in the outgoing lens group 32, so that the lens 35 has a positive refractive power as a whole.
In the fourth embodiment, the lens 34B having the positive refractive power of the incident lens set 31B and the lens 35 having the positive refractive power of the outgoing lens set 32 are respectively arranged in the light traveling direction L.
According to the configuration shown in the fourth embodiment, the incident lens set 31B as a whole has a negative refractive power, so that the exit lens set 32 and the front focal position of the exit lens set 32 can be reduced. Since it can arrange | position in between, as shown to FIG.2,3,4, the full length of the beam expander 30B can be shortened compared with the 2nd, 3rd Example.

  In addition, the shape of the lens which comprises the incident lens group 31 and 31B shown in this Embodiment, and the output lens group 32 is not limited.

It is a conceptual diagram which shows HUD concerning this invention. It is a schematic block diagram explaining one Example (2nd Example) of the beam expander applied to the HUD optical system concerning this invention. It is a schematic block diagram explaining the other Example (3rd Example) of the beam expander applied to the HUD optical system concerning this invention. It is a schematic block diagram explaining the other Example (4th Example) of the beam expander applied to the HUD optical system concerning this invention. It is a schematic block diagram which shows the conventional HUD.

10 Head-up display (HUD)
DESCRIPTION OF SYMBOLS 11 Display apparatus 12 Observer (driver | operator) viewpoint 13 Condensing lens group 14 Lens with positive refractive power 15 Lens with negative refractive power 16 Windshield 17 Combiner 18 Virtual image (display image)
20 Moving means 30 Beam expander 31, 31B Incident lens set 32 Exit lens set

Claims (5)

  In a head-up display in which a display image projected from a display device is reflected by a reflection unit, and an observer visually recognizes the reflection image from the reflection unit, the display image is on an optical path between the display device and the reflection unit. An optical system for a head-up display, comprising a condensing lens group for changing the magnification of the lens.   2. The head-up display optical system according to claim 1, wherein the condensing lens group is provided with a moving means movable in an optical axis direction.   3. The head-up display according to claim 1, wherein the condenser lens set includes a lens having a positive refractive power and a lens having a negative refractive power for correcting chromatic aberration. Optical system.   The optical system for a head-up display according to any one of claims 1 to 3, further comprising a beam expander formed by combining a plurality of condensing lens groups having different refractive powers. 5. The head-up display according to claim 4, wherein in the beam expander, one of the condensing lens groups is a lens group having a negative refractive power, and the other is a lens group having a positive refractive power. Optical system.

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