JPWO2018066675A1 - Variable magnification projection optical system and image display apparatus - Google Patents

Abstract

To provide a variable magnification projection optical system that easily changes the display distance of a virtual image at an arbitrary position in a screen. The variable magnification projection optical system 13 reflects the image light from the first projection optical system 30 that forms a first intermediate image from the image of the display element 11 and the first intermediate image TI1 by the combiner 20 that is a display screen. And a second projection optical system 40 that displays a virtual image through the display screen. The second projection optical system 40 includes a variable focus optical system 51 that can change the display position of the virtual image.

Description

  The present invention relates to a variable magnification projection optical system in which an image as a virtual image is displayed ahead of a line of sight and in which the projection position of the virtual image is variable, and an image display apparatus using the variable magnification projection optical system.

  A head-up display (hereinafter, referred to as HUD) is a display device that performs virtual image projection display, and is a projection that displays an image displayed on a display element such as DMD (Digital Micromirror Device) or LCOS (Liquid crystal on silicon) as a virtual image. It has an optical system and a display screen such as a windshield or a combiner for displaying the virtual image. This HUD is an instrument panel such as an instrument panel (such as an instrument panel provided at the driver's seat of a car) in that the driver while driving can check the display without significantly moving the sight or the viewpoint. It has the merit of reducing the risk of the driver as compared with the device that displays the information). In the future, it is expected that the HUD will be actively used as a device for performing display to support the driver's safe driving. At that time, it is necessary to convey hazard information to be conveyed, information to be noted, etc. to the driver in various ways, and a display that raises the recognition of such information is required.

  As an example of the display method of transmitting information to the driver, there is a method of changing the display position (or display distance) of the virtual image (see, for example, Patent Documents 1 to 4). In Patent Document 1, in the reflection mirror used for the HUD optical system, at least two reflection mirror surfaces having different curvatures are provided, and switching is performed by their rotation to make the display distance variable. In patent document 2, a virtual image is displayed using several display boards from which the optical path distance to a reflector differs in the structure which does not have a movable part, and the display distance of a virtual image is changed by switching the display of several display boards. I am doing it. In Patent Document 3, the HUD optical system includes a focusing lens that changes the display image by lens driving. The objective of this condenser lens is to change the size of the display image, and the display position in the optical axis direction of the virtual image is adjusted by using, for example, a beam expander for the condenser lens. In Patent Document 4, in the HUD optical system, a relay optical system is provided between the display element and the imaging optical system, and an intermediate image is formed by the relay optical system. By changing the position of the optical element used in the relay optical system, the position of the intermediate image is changed, and the display position of the virtual image is changed. In patent document 4, a stereoscopic vision image is obtained by superimposing each image of the intermediate image which changed the position within 1/60 second, for example.

  However, in patent document 1, since there are two mirror surfaces, the display distance of a virtual image is limited to two points, and when it is going to increase the display distance number, there exists a problem that the number of mirror sheets (surface) will increase. Further, in Patent Document 2, when the number of display distances is increased, the number of display panels needs to be increased, and not only the apparatus becomes complicated and enlarged, but also the positions of the display panels become fixed. There is a problem that it is difficult to change the display distance of the virtual image at the position. Further, Patent Document 3 does not disclose the effect of changing the virtual image position, and does not disclose a specific configuration example of scaling. Moreover, in patent document 4, although the diffusion plate (intermediate screen) is arrange | positioned in the position of an intermediate image, it limits to the case where a light scanning type device is used for a display panel. In Patent Document 4, in order to change the display position of the virtual image, it is necessary to move this intermediate screen. Here, in order to make the display easy to use while enlarging the viewing angle when displaying the virtual image, in order to enlarge the range (eye box) that can be observed even if the eye of the driver (observer) moves, It is necessary to increase the magnification of the relay optical system to some extent. As a result, the size of the intermediate screen increases, which causes problems such as a large moving mechanism. In addition, when attempting to miniaturize the apparatus by using a small display panel, when it is desired to increase the eye box while securing the viewing angle, the intermediate screen is selected regardless of whether the display panel is of the light scanning type or not. In this case, the mechanism for moving the intermediate screen becomes large.

Japanese Patent Application Laid-Open No. 9-185012 JP 2004-168230 A Unexamined-Japanese-Patent No. 2007-94394 JP 2008-180759 A

  The present invention has been made in view of the above background art, and it is an object of the present invention to provide a variable power projection optical system which easily changes the display distance of a virtual image at an arbitrary position in a screen.

  Another object of the present invention is to provide an image display apparatus using the variable magnification projection optical system.

  In order to solve the above problems, the variable magnification projection optical system according to the present invention includes a first projection optical system that forms a first intermediate image from an image of a display element, and a display screen that reflects image light from the first intermediate image. And a second projection optical system that displays a virtual image through the display screen, and the second projection optical system includes a variable focus optical system that changes the display position of the virtual image.

  In order to solve the above-mentioned subject, the image display device concerning the present invention mounts the above-mentioned variable magnification projection optical system.

FIG. 1A is a side sectional view showing a state in which the image display device of the first embodiment is mounted on a vehicle body, and FIG. 1B is a front view from the inside of a vehicle for explaining the image display device. It is an expanded side sectional view explaining the image display apparatus of FIG. 1A. It is a conceptual diagram explaining the structure of the image display apparatus of FIG. 1A. FIG. 4A is a diagram for explaining one modification, and FIG. 4B is a diagram for explaining another modification. FIG. 5A is a cross-sectional view for explaining image formation by the image display device, and FIG. 5B is a view for explaining an eye box capable of observing a virtual image. FIG. 6A is a front view from the inside of a vehicle for explaining an image display device according to a second embodiment, and FIG. 6B is a side sectional view for explaining the image display device. It is a side sectional view explaining the image display device of a 3rd embodiment.

First Embodiment
The variable magnification projection optical system and the image display apparatus incorporating the same according to the first embodiment of the present invention will be described below.

  FIGS. 1A and 1B are conceptual side cross sectional views and a front view illustrating an image display apparatus 100 of the present embodiment and a use state thereof. The image display device 100 is mounted, for example, in a vehicle body 2 as a head-up display device, and includes a drawing unit 10 and a combiner 20. The image display apparatus 100 is for displaying a virtual image or a virtual image of image information displayed on a display element 11 to be described later through a display screen (in the example of the present embodiment, the combiner 20).

  Of the image display device 100, the drawing unit 10 is installed so as to be embedded in the dashboard 4 of the vehicle body 2, and emits the display light HK corresponding to the image including the driving related information toward the combiner 20. The combiner 20 is a display screen that functions as a semitransparent concave mirror, is erected on the dashboard 4 by the support of the lower end, and reflects the display light HK from the drawing unit 10 toward the rear of the vehicle body 2. That is, the combiner 20 is an independent type installed separately from the front window 8. The display light HK reflected by the combiner (display screen) 20 is guided to an eye box SY (see FIG. 5B) corresponding to the pupil HT of the driver UN and its peripheral position. The driver UN can observe the display light HK reflected by the combiner 20, that is, the display image IM as a virtual image in front of the vehicle body 2. On the other hand, the driver UN can observe external light transmitted through the combiner 20, that is, a real image such as a front view. As a result, the driver UN can observe the display image (virtual image) IM including the driving related information and the like formed by the reflection of the display light HK at the combiner 20, superimposed on the outside world image behind the combiner 20. .

  As shown in FIGS. 2 and 3, the drawing unit 10 includes a drawing device 12 including the display element 11, a variable magnification projection optical system 13, and a housing 14. Note that FIG. 3 exemplifies the configuration of the image display device 100, and the configuration of the image display device 100 is appropriately changed according to the specification, the installation location, and the like.

  Although the detailed description is omitted, in addition to the display element 11, the drawing device 12 includes a display drive circuit that causes the display element 11 to perform a display operation, an LED that emits light for illuminating the display element 11, and other light sources A homogenization optical system or the like for homogenizing the light from the light source is provided. The display element 11 may be a reflective element such as DMD or LCOS, or a transmissive element such as liquid crystal. In particular, when a DMD is used for the display element 11, an image can be switched at high speed while maintaining the brightness, which is advantageous for display.

  The variable magnification projection optical system 13 is a first projection optical system 30 that forms a first intermediate image corresponding to the image formed on the display element 11, and a combiner that is a display screen with the image light corresponding to the first intermediate image TI1. And 20 a second projection optical system 40 for displaying a virtual image by being incident on the light source 20. It is desirable that the variable magnification projection optical system 13 have at least one aspheric surface. Since the variable magnification projection optical system 13 has an aspheric surface, the number of lenses and mirrors constituting each lens group in the variable magnification projection optical system 13 can be reduced while securing optical performance, and the optical system can be miniaturized. be able to.

  In the variable magnification projection optical system 13, an intermediate screen mSC is disposed at a position where the first intermediate image TI1 is formed between the first projection optical system 30 and the second projection optical system 40. Since the first intermediate image TI1 does not move in the direction of the optical axis AX or the like, there is no need to move the intermediate screen mSC, and the depth position of the display image (virtual image) IM is changed only by the action of the variable focus optical system 51 described later And both a viewing angle and an eye box can be enlarged. The intermediate screen mSC is a diffusion plate in which the light distribution angle is controlled to a desired angle. For the diffusion plate, for example, ground glass, a lens diffusion plate, a micro lens array or the like is used. By providing the diffusion plate as the intermediate screen mSC, it is possible to relatively increase the light use efficiency of the optical system while easily securing the viewing angle and the eye box size. In addition, if the light distribution angle of diffusion is too narrow, the eyebox size will become small. Conversely, if the light distribution angle of diffusion is too large, it is necessary to reduce the F value of the optical system (particularly, relay optical system 50 described later) in order to increase the light utilization efficiency, which makes it difficult to secure performance. The diameter and the number of

For the diffusion plate which is the above-described intermediate screen mSC, the light distribution angle of the diffusion plate is α, and the spread angle of the on-axis marginal ray from the display element 11 incident on the first projection optical system 30 is θ1. Assuming that the magnification of the optical system 30 is β1 and the on-axis marginal ray incident on the second projection optical system 40 is θ2, the light distribution angle α may be set by the following conditional expression (2).
α ≒ {θ ^{2 2} − (θ 1 / β 1) ² } (2)
Conditional expression (2) is applied to the divergence angle of the intermediate screen mSC used at the position of the first intermediate image TI1 of the variable magnification projection optical system 13. By satisfying the conditional expression (2), it is possible to efficiently use the light flux taken into the second projection optical system 40.

  As shown in FIG. 3, the first projection optical system 30 has a plurality of lenses or lens groups on which the image of the display element 11 is projected. In the illustrated example, the first projection optical system 30 is configured of four lenses.

  The second projection optical system 40 has a relay optical system 50 for relaying the first intermediate image TI1, and a third projection optical system 60 disposed on the side of the combiner 20 which is a display screen with respect to the relay optical system 50. ing. The second projection optical system 40 forms a second intermediate image TI2 between the relay optical system 50 and the third projection optical system 60. By arranging the second projection optical system 40 with two optical systems, ie, the relay optical system 50 and the third projection optical system 60, the entire magnification ratio is divided into the relay optical system 50 and the third projection optical system 60. Can. As a result, the field angle and the eye box size of the entire system can be increased while increasing the F value of the relay optical system 50, and the enlargement of the relay optical system 50 is prevented while the specification is easy to use. It is possible to secure the optical performance such as the sex and astigmatic difference.

  The second projection optical system 40 has a variable focus optical system 51 that makes the display position in the depth direction of the display image (virtual image) IM variable. The variable focus optical system 51 is disposed in the relay optical system 50. As a result, the variable focus optical system 51 can be miniaturized, and the movable mechanism etc. can be simplified. The variable focal point optical system 51 is configured to move at least one lens in any of an optical axis AX direction, a vertical direction in a plane perpendicular to the optical axis AX, and a direction combining the optical axis AX direction and the vertical direction. It has become. In particular, in the case of changing only the display position in the depth direction, at least one lens is moved in the optical axis AX direction. In the illustrated example, two lenses are integrally moved in the direction of the optical axis AX as one set. As a result, it is possible to change the magnification without being restricted by the lens diameter and the focus variable range which occur when using a variable focus lens described later for the variable focus optical system 51, and the variable magnification range, the viewing angle and the eye box size Such specifications can be secured large. The lens included in the variable focus optical system 51 has a configuration in which the curvature changes in a plane perpendicular to the optical axis AX, and the lens in which the curvature changes in a plane perpendicular to the optical axis AX is perpendicular to the optical axis AX When the lens is moved in the vertical direction, the curvature of the lens changes, so that it is possible to change the magnification as in the case of a variable-focus lens or when the lens is moved in the direction of the optical axis AX. . Further, the display position in the plane perpendicular to the optical axis AX can be changed, and the display range can be expanded.

  The variable magnification projection optical system 13 changes the display position or the display distance in the depth direction of the display image IM in accordance with the change of the focal length by the variable focus optical system 51. As described above, the variable magnification projection optical system 13 is configured to form the second intermediate image TI2 between the relay optical system 50 and the third projection optical system 60. When multiplication is performed, the position of the second intermediate image TI2 moves along the optical axis AX. Thereby, the display image IM is a position (position of the display image IM3) far from the position (position of the display image IM1) near the combiner 20 (position of the display image IM2) from the position near the combiner 20 (position of the display image IM2). The position is changed and displayed continuously or intermittently. For example, pseudo 3D virtual image display can be performed if the display image IM is continuously displayed by changing the display distance from the farthest position to the nearest position at high speed (for example, within 1/30 seconds). it can.

  The variable focus optical system 51 may be configured to have at least one focus variable lens instead of moving the lens. The variable focus lens changes the lens curvature (that is, the curvature of the optical surface) using either the elastic body or the liquid to change the display position of the virtual image. As shown in FIG. 4A, the lens 51a using an elastic body applies, for example, the action force of the actuator 81 to the elastic body portion 55a to change the shape of the elastic body portion 55a to change the focal point. Further, as shown in FIG. 4B, the lens 51b using a liquid has, for example, a configuration in which two kinds of liquids 56a and 56b of water (aqueous solution) and oil and an electrode 56e are sealed in a container 56c. By applying a voltage from the power supply unit 181 to the electrode 56e, the refractive power is changed by changing the shape of the contact surface between oil and water, and the focus is changed. By using a variable-focus lens as the variable-focus optical system 51, the focus can be changed without using a drive mechanism for moving the lens as described above in the direction of the optical axis AX or the like. It becomes possible.

  The relay optical system 50 is a magnifying projection system, and has a plurality of lenses or lens groups. In the example shown in FIG. 3, the relay optical system 50 is configured of seven lenses. The relay optical system 50 has, for example, a variable focus optical system 51 on the side of the combiner 20 which is a display screen among a plurality of lenses or lens groups. The relay optical system 50 performs magnification change by moving one or two variable focus optical systems 51 as a movable lens group in the direction of the optical axis AX or the like. The lens weight of the variable focus optical system 51 can be reduced by reducing the number of lenses. As a result, it is not necessary to make the mechanism for driving the variable focus optical system 51 large in scale, and the enlargement and the complication of the apparatus can be prevented. Further, if the variable focus optical system 51 is configured by a plastic lens, further weight reduction can be achieved.

When the magnification of the relay optical system 50 is β2L when the display position of the display image (virtual image) IM is the furthest (position of the display image IM3 shown in FIG. 3), the relay optical system 50 satisfies the following conditional expression (1) Meet.
0.75 <β2L <2.0 (1)
Conditional expression (1) defines the magnification of the relay optical system 50 that performs magnification variation. By falling below the upper limit of the value β2L of the conditional expression (1), it is not necessary to increase the distance between the relay optical system 50 and the third projection optical system 60 in order to secure the eye box size. Thereby, the optical system does not become large, and the distance from the second projection optical system 40 (specifically, the final surface of the third projection optical system 60) which is the final optical system to the pupil position of the driver UN becomes long. It can also prevent. Also, when the viewing angle is set large, it is possible to prevent the size of the final optical system in the radial direction from becoming too large. Further, by exceeding the lower limit of the value β2L of the conditional expression (1), the F value of the relay optical system 50 for securing the eye box size becomes relatively large to such an extent that the relay optical system 50 is not burdened. Performance can be ensured.

It is more desirable to satisfy the following expression about conditional expression (1).
1.0 <β2L <1.6 (1) '

  The third projection optical system 60 has a plurality of mirrors. In the illustrated example, the third projection optical system 60 is configured of two mirrors MR1 and MR2. The mirror constituting the third projection optical system 60 can be a convex surface, a concave surface, or a flat surface, and in the case of a curved surface, not only a spherical surface but also an aspheric surface, a free curved surface, or the like. The third projection optical system 60 cooperates with a combiner 20 described later to construct a virtual image enlargement projection system.

  As shown in FIG. 2, the housing 14 has an opening 14 a for transmitting the display light HK, and a film-like or thin plate-like light transmitting member 15 can be disposed in the opening 14 a.

  The combiner 20 is a plate-like member, and is provided on the first optical surface 21 provided on the observation side where the driver UN who is the observer is located or on the seat 6 (see FIG. 1A) side, and on the anti-observation side or the front window 8 side. And a second optical surface 22. The first optical surface 21 is a concave curved surface, and is an aspheric surface or a free curved surface. The second optical surface 22 is a convex curved surface (a concave curved surface when viewed from the observer side), and is an aspheric surface or a free-form surface. The first optical surface 21 is obtained by forming a half mirror coat 20b having a reflectance of, for example, 5 to 30% on the main body layer 20a which is a base material, and appropriately reflects the display light HK. The ambient light GK can be transmitted to a desired degree. An anti-reflection film and a protective coat are formed on the second optical surface 22. There is also a case where the anti-reflection film or the like is not formed on the second optical surface 22.

  As shown in FIG. 5A, the display light HK reflected by the combiner 20 is guided to the pupil HT of the driver UN. Here, a virtual image ray KK which extends the display light HK behind the combiner 20 forms a display image (virtual image) IM at a predetermined position in front of the driver's pupil HT. The distance d1 from the pupil HT to the combiner 20 is, for example, about 0.5 to 1 m depending on the specifications of the vehicle body 2, and the distance d2 from the combiner 20 to the display image IM is about 1 m or more. The viewing angle is about -10 to -15 degrees. The eye box SY shown in FIG. 5B is set to cover the position of the pupil HT of the standard driver UN, and is set to, for example, a size of 10 to 15 cm in width and 5 to 8 cm in height.

  The first optical surface 21 disposed on the pupil HT side of the combiner 20 displays the image formed on the display element 11 via the variable power projection optical system 13 with less distortion as the display image IM with respect to the pupil HT or Project Under the present circumstances, the 1st optical surface 21 can form the display image IM without distortion by the optical surface shape. In the case where the second optical surface 22 is not provided with the anti-reflection film, or in the case where a slight reflection is left by the anti-reflection film, the display light which is branched through the first optical surface 21 also in the second optical surface 22 Partially reflect HK. In this case, the display light reflected by the second optical surface 22 behind (afterward branching) (hereinafter referred to as sub display light for convenience) passes through the first optical surface 21 and is incident on the pupil HT, so the display image IM And may form a double image. However, if the sub-display light reflected by the second optical surface 22 travels so as to be emitted from the same point on the display image IM in relation to the original display light HK, a virtual image and a sub-display by the display light HK The formation of a double image can be avoided by overlapping with a virtual image by light. The curvature or inclination angle of the second optical surface 22 and the thickness of the main body layer 20 a may be adjusted with reference to the first optical surface 21 in order to control the traveling direction of the sub display light.

  The variable magnification projection optical system 13 or the image display apparatus 100 described above includes the second projection optical system 40 that displays the first intermediate image TI1 formed by the first projection optical system 30 as a virtual image through the combiner 20 as a display screen. The second projection optical system 40 has a variable focus optical system 51 that makes the display position variable, thereby changing the display position of the display image (virtual image) IM without moving the position of the first intermediate image TI1. Can. As a result, even when the intermediate screen mSC or other optical element is used at the position of the first intermediate image TI1, a large-scale mechanism for moving the optical element is not necessary, and the apparatus can be prevented from becoming complicated and large. .

  If the optical system can be made smaller by reducing the size of the display element 11, the device can be made smaller. In that case, if it is intended to secure a viewing angle at the time of performing a virtual image display, On the other hand, the enlargement magnification for enlarging and projecting the image by the variable magnification projection optical system 13 is increased. If it is attempted to achieve such projection with a large magnifying power with a projection optical system without an intermediate image, it is difficult to enlarge the range (eye box) that can be observed even if the driver (observer) 's eyes move There is a problem that it becomes difficult to use as an actual device.

  On the other hand, in the optical system as in this embodiment for forming an intermediate image, since the projection in which the enlargement magnification is distributed to each of the two optical systems sandwiching the first intermediate image TI1 becomes possible, the eye box is made wide An optical system becomes possible. Further, in order to increase both the viewing angle and the eye box size, it is desirable to use an intermediate screen mSC configured of a diffusion plate or the like at the position of the intermediate image (that is, the first intermediate image TI1). As described above, in such an optical system, when the display element 11 side is the first projection optical system 30 and the display screen side is the second projection optical system 40 with respect to the first intermediate image TI1, the projection distance In order to make it variable, it is necessary to provide a variable focus optical system 51 which makes the focal length variable in either or both optical systems.

  Here, if the variable focus optical system 51 is provided in the first projection optical system 30, the imaging position of the first intermediate image TI1 is in the direction of the optical axis AX along with the focal length fluctuation of the variable focus optical system 51. Will move to In the case of using the intermediate screen mSC at the position of the first intermediate image TI1, it is necessary to mechanically move the position of the intermediate screen mSC, which makes the mechanism complicated and makes it difficult to miniaturize the apparatus. Also, considering an optical system that tries to obtain a pseudo 3D virtual image display by changing the display distance at high speed, if mechanical movement occurs, it can not respond to the speed and the magnification change can not catch up. In order to solve these problems, the variable focus optical system 51 is provided in the second projection optical system 40 instead of the first projection optical system 30. As a result, zooming can be performed while the position of the first intermediate image TI1 formed by the first projection optical system 30 is fixed, the problem of the movement of the intermediate screen mSC can be eliminated, and the display position of the display image IM can be variable.

  An image display apparatus 100 provided with a variable magnification projection optical system 13 is applied to a head-up display (HUD) apparatus or the like used for an automobile or the like. By changing the display distance of the display image IM with the above-mentioned configuration, for example, in the HUD device, the distance and position at which the driver (observer) UN actually encounters the danger ahead during driving. Can be displayed superimposed on the image that will be a warning. As a result, even if the position of the eye or pupil HT moves due to movement of the head of the driver UN, the display does not move, and information can be naturally transmitted to the driver UN without discomfort. In addition, if the display distance from the farthest position to the nearest position can be changed within 1/30 seconds, more preferably within 1/60 seconds, the display image (virtual image) IM with a changed distance is the eye of a person It looks like almost simultaneous display from. As a result, it is possible to simultaneously transmit information such as a plurality of dangers having different distances to the driver UN, and to support the safe driving of the driver UN.

〔Example〕
Hereinafter, embodiments of the variable magnification projection optical system 13 of the present invention will be shown.

Example 1
The data of the variable magnification projection optical system 13 of Example 1 is shown in Table 1 below. In Table 1 below, the number of the lens unit constituting the variable magnification projection optical system 13 is represented by “m”, the focal length of each lens unit is represented by “fm”, and the display position is at a long distance. The distance between the lens units is represented by "dm (LR)", and the distance between the lens units when the display position is close is represented by "dm (SR)". Also, the display element is represented by "DD" and the intermediate screen is represented by "mSC". Further, the distance “dm” of each lens group in the column “M” is the distance from the final optical system (that is, the third projection optical system 60) to the pupil HT (that is, the position of the driver's eyes) The interval “dm” in the column of “N” is the distance from the pupil HT to the display position of the virtual image. As for the interval "dm", the distance between the third and fourth lens groups and the distance between the fourth and fifth lens groups are respectively changed when the virtual image display is at a long distance and at a short distance. . In the present embodiment, the long distance is about 50 m and the short distance is about 3 m, but the distance between the third and fourth lens groups and the distance between the fourth and fifth lens groups (that is, the fourth By changing the movement amount of the lens group, these distance ranges can be made wider or narrower. Moreover, although not shown in the table, in actual use, the display screen which is the combiner 20 or the like for displaying a virtual image is disposed between the sixth lens group and the eye of the driver (that is, the pupil HT). Be done. The sign “←” indicates that it is the same as the value on the left side. The above is the same for the second and subsequent embodiments unless otherwise described.
[Table 1]
m fm dm (LR) dm (SR)
DD
52.50 ←
1 45.000
315.00 ←
mSC
120.00 ←
2 120.000
173.33 ←
3-74.270
16.00 6.00
4 63.903
488.78 498.78
5-500.000
94.63 ←
6 271.462
M 1499.43 ←
N-50132.33-2999.58

The size and the viewing angle of the display element 11 of Example 1 are shown below.
Display element horizontal size (unit: mm): 9.86
Horizontal viewing angle (unit: degree): -12.

  In the present embodiment, the value β2L of the conditional expression (1) is 1.5 times, and the F value at the time of long-distance projection of the two groups is about 3.42. The eye box size at that time is secured to about 127 to 116 mm in the horizontal direction of the screen.

  The variable power projection optical system 13 of Example 1 substantially consists of a first projection optical system 30, an intermediate screen mSC, and a second projection optical system 40 in order from the display element 11 side. The first projection optical system 30 is composed of a first lens group. The second projection optical system 40 is composed of second to sixth lens groups. Here, the second projection optical system 40 includes a relay optical system 50 configured by the second to fourth lens groups, and a third projection optical system 60 configured by the fifth and sixth lens groups. Among them, the fourth lens group of the relay optical system 50 is a variable focus optical system 51. The fourth lens group as the variable focus optical system 51 performs zooming by moving in the direction of the optical axis AX.

  Although the focal length of each lens group and the distance between each lens group are shown in this embodiment, each lens group may be composed of one lens or one mirror, or a plurality of lenses Alternatively, it may be composed of a plurality of mirrors. Furthermore, although not shown in the embodiment, the size of the entire optical system can be reduced by disposing a mirror for bending the optical path in the optical path of the optical system. The third projection optical system 60 may be configured by at least one mirror. Since the degree of freedom of the light path to the combiner 20 which is a display screen is increased and no chromatic aberration occurs, it is preferable to use a mirror, particularly a mirror with a free curved surface.

  In the present embodiment, the light beam emitted from the second lens unit is afocal, but it is not necessary to be afocal in particular, and the size of the optical system, the focal length of each lens unit, the F value, the magnification, etc. It can be changed to a desirable configuration according to the specification of Furthermore, in the present embodiment, the position of the fourth lens group moved in order to change the focal length in the relay optical system 50 is set to the position of the relay optical system 50 in order to reduce the burden on the mechanism for moving the lens. Although they are set to be substantially the same as the pupil position, they may be set at different positions in consideration of specifications and other factors in design.

(Example 2)
The data of the variable magnification projection optical system 13 of Example 2 is shown in Table 2 below.
[Table 2]
m fm dm (LR) dm (SR)
DD
52.00 ←
1 45.000
334.29 ←
mSC
120.00 ←
2 120.000
169.78 ←
3-67. 000
16.00 6.00
4 53.262
348.66 358.66
5-350.000
62.27 ←
6 190.278
M 1114.94 ←
N-50135.22-3002.97

The size and viewing angle of the display element 11 of Example 2 are shown below.
Display element 11 horizontal size (unit: mm): 9.86
Horizontal viewing angle (unit: degree): -12.1

  In the present embodiment, the value β2L of the conditional expression (1) is 1.0 times, and the F value at the time of long-distance projection of the two groups is about 2.31. The size of the eye box at that time is approximately 135 to 118 mm in the horizontal direction of the screen.

  The variable power projection optical system 13 of Example 2 substantially consists of a first projection optical system 30, an intermediate screen mSC, and a second projection optical system 40 in order from the display element 11 side. The first projection optical system 30 is composed of a first lens group. The second projection optical system 40 is composed of second to sixth lens groups. Here, the second projection optical system 40 includes a relay optical system 50 configured by the second to fourth lens groups, and a third projection optical system 60 configured by the fifth and sixth lens groups. Among them, the fourth lens group of the relay optical system 50 is a variable focus optical system 51. The fourth lens group as the variable focus optical system 51 performs zooming by moving in the direction of the optical axis AX.

(Example 3)
The data of the variable magnification projection optical system 13 of Example 3 is shown in Table 3 below.
[Table 3]
m fm dm (LR) dm (SR)
DD
52.05 ←
1 45.000
332.23 ←
mSC
120.00 ←
2 120.000
170.13 ←
3-68. 900
18.00 8.00
4 67.517
562.70 572.70
5-550.000
223.80 ←
6 403.722
M 2391.83 ←
N-50231.36-2999.05

The size and the viewing angle of the display element 11 of Example 3 are shown below.
Display element 11 horizontal size (unit: mm): 9.86
Horizontal viewing angle (unit: degree): -12.

  In the present embodiment, the value β2L of the conditional expression (1) is 2.0 times, and the F value at the time of long-distance projection of the two groups is about 4.54. The eye box size at that time is secured at about 137 to 133 mm in the horizontal direction of the screen.

  The variable power projection optical system 13 of the third embodiment substantially consists of a first projection optical system 30, an intermediate screen mSC, and a second projection optical system 40 in this order from the display element 11 side. The first projection optical system 30 is composed of a first lens group. The second projection optical system 40 is composed of second to sixth lens groups. Here, the second projection optical system 40 includes a relay optical system 50 configured by the second to fourth lens groups, and a third projection optical system 60 configured by the fifth and sixth lens groups. Among them, the fourth lens group of the relay optical system 50 is a variable focus optical system 51. The fourth lens group as the variable focus optical system 51 performs zooming by moving in the direction of the optical axis AX.

(Example 4)
The data of the variable magnification projection optical system 13 of Example 4 is shown in Table 4 below.
[Table 4]
m fm dm (LR) dm (SR)
DD
51.90 ←
1 45.000
338.48 ←
mSC
120.00 ←
2 120.000
169.07 ←
3-63.200
16.00 6.00
4 47.560
244.05 254.05
5-300.000
80.14 ←
6 168.949
M 917.95 ←
N-50081. 85-299. 93

The size and the viewing angle of the display element 11 of Example 4 are shown below.
Display element 11 horizontal size (unit: mm): 9.86
Horizontal viewing angle (unit: degree): -12.

  In the present embodiment, the value β2L of the conditional expression (1) is 0.79 times, and the F value at the time of long-distance projection of the two groups is about 1.85. At this time, the eye box size is secured to about 136 to 116 mm in the horizontal direction of the screen.

  The variable power projection optical system 13 of the fourth embodiment substantially consists of a first projection optical system 30, an intermediate screen mSC, and a second projection optical system 40 in this order from the display element 11 side. The first projection optical system 30 is composed of a first lens group. The second projection optical system 40 is composed of second to sixth lens groups. Here, the second projection optical system 40 includes a relay optical system 50 configured by the second to fourth lens groups, and a third projection optical system 60 configured by the fifth and sixth lens groups. Among them, the fourth lens group of the relay optical system 50 is a variable focus optical system 51. The fourth lens group as the variable focus optical system 51 performs zooming by moving in the direction of the optical axis AX.

(Example 5)
The data of the variable magnification projection optical system 13 of Example 5 are shown in Table 5 below. As for the interval “fm”, the focal length of the third lens group is changed between when the virtual image display is at a long distance and at a near distance. In this embodiment, the long distance is about 50 m and the short distance is about 3 m, but if the focus variable range between the third lens units is changed, these distance ranges can be made wider or narrower. . Further, although not shown in the table, in actual use, a display screen which is a combiner 20 or the like for displaying a virtual image is disposed between the fifth lens group and the eyes of the driver.
[Table 5]
m fm (LR) fm (SR) dm (LR) dm (SR)
DD
52.50 ←
1 45.000 ←
315.00 ←
mSC
120.00 ←
2 120.000 ←
173.33 ←
3 180.000 265.000
450.00 ←
4-500.000 ←
94.63 ←
5 271.462 ←
M 1499.43 ←
N-50132.33-2991.13

The size and the viewing angle of the display element 11 of Example 5 are shown below.
Display element 11 horizontal size (unit: mm): 9.86
Horizontal viewing angle (unit: degree): -12.

  In the present embodiment, the value β2L of the conditional expression (1) is 1.5 times, and the F value at the time of long-distance projection of the two groups is about 3.42. The eye box size at that time is secured about 127 mm in the horizontal direction of the screen.

  The variable power projection optical system 13 of the fifth embodiment comprises, in order from the display element 11 side, a first projection optical system 30, an intermediate screen mSC, and a second projection optical system 40. The first projection optical system 30 is composed of a first lens group. The second projection optical system 40 includes second to fifth lens groups. Here, the second projection optical system 40 includes a relay optical system 50 configured by the second and third lens groups, and a third projection optical system 60 configured by the fourth and fifth lens groups. Among them, the third lens group of the relay optical system 50 is a variable focus optical system 51. The variable power is performed by using the third lens group as the variable focus optical system 51 as a variable focus lens.

  In the present embodiment, the focal lengths of the respective lens units and the intervals between the respective lens units are shown, but each lens unit other than the third lens unit may be configured by one lens or one mirror. It may be composed of a plurality of lenses or a plurality of mirrors. As the variable-focus lens used for the third lens group, for example, a liquid lens in which a liquid is sandwiched between elastic bodies, a lens which changes the curvature to change the curvature of the elastic body, a lens which electrically changes the focus such as a liquid crystal lens, etc. Can be mentioned.

  Further, in the present embodiment, the position of the third lens unit, which is a focus variable lens in the relay optical system 50, is made to be substantially the same as the pupil position of the relay optical system 50 in order to reduce the lens diameter. Although set, it may be set at a different position in consideration of specifications and other factors in design.

Second Embodiment
The variable magnification projection optical system according to the second embodiment and the image display apparatus incorporating the same will be described below. Note that the variable power projection optical system and the like of the second embodiment is a modification of the variable power projection optical system and the like of the first embodiment, and items that are not particularly described are the same as those of the first embodiment.

  As shown in FIGS. 6A and 6B, in the case of the image display apparatus 100 according to the second embodiment, the front window 8 incorporates a thin middle layer 120, and a rectangular reflection area provided on the front of the driver's seat of the front window 8. 8d functions as a display screen.

  In the illustrated example, the inner surface of the front window 8 functions as the first optical surface 21, and the inner surface of the intermediate layer 120 functions as the second optical surface 22. In this case, the shape of the first optical surface 21 can be adjusted to some extent by the molding or processing of the inner side surface of the front window 8, but the adjustment range is narrow. The shape of the second optical surface 22 can be adjusted by adjusting the arrangement and thickness of the intermediate layer 120.

Third Embodiment
The variable magnification projection optical system according to the third embodiment and the image display apparatus incorporating the same will be described below. The variable power projection optical system and the like of the third embodiment are modifications of the variable power projection optical system and the like of the first and second embodiments, and items that are not particularly described are the same as those of the first embodiment and the like.

  As shown in FIG. 7, in the case of the image display apparatus 100 according to the third embodiment, a combiner portion 220 as a screen is provided inside a rectangular reflection area 8d (see FIG. 6A) provided in front of the driver's seat of the front window 8. It is pasted.

  In the illustrated example, the inner surface of the combiner portion 220 functions as the first optical surface 21, and the outer surface of the front window 8 functions as the second optical surface 22.

  Although the variable magnification projection optical system and the like according to the embodiment have been described above, the variable magnification projection optical system and the like according to the present invention are not limited to the above. For example, in the first embodiment, the arrangement of the image display apparatus 100 can be reversed upside down, and the combiner 20 can be arranged at the top of the front window 8 or at the sun visor position. A combiner 20 is arranged. Also, the combiner 20 may be arranged to be able to be displayed at a position corresponding to a conventional mirror of a motor vehicle.

  In the above-described embodiment, the outline of the combiner 20 and the outline of the reflection area 8d are not limited to the rectangular shape, and can have various shapes.

  The drawing unit 10 shown in FIG. 2 is merely an example, and the configuration of the variable magnification projection optical system 13 can be appropriately changed, or the display element 11 can be replaced with another type of display element.

  In the above embodiment, the intermediate screen mSC is a diffusion plate, but the intermediate screen mSC may be a microlens array. In this case, a desired light distribution angle can be obtained by controlling the curvature and the like of each of the microlenses, and the light utilization efficiency can be increased.

  Although the second intermediate image TI2 is formed in the above embodiment, the second intermediate image TI2 may not be formed.

  In FIG. 3, the variable focus optical system 51 is the lens group on the display screen side of the relay optical system 50, but may be another lens group or lens according to the optical design or specification.

  Although FIG. 3 illustrates three display positions of the display image (virtual image) IM, the position at which the display image IM is displayed can be appropriately set including the number of display positions. In addition, the display of the display image IM can be performed continuously or intermittently by changing the position.

  In the above embodiment, the size of the display image IM formed by the variable magnification projection optical system 13 or the like is not limited to one proportionally changing according to the display distance (or display position) of the display image IM, but various sizes Can be adjusted.

Claims (10)

A first projection optical system that forms a first intermediate image from an image of the display element;
A second projection optical system that displays a virtual image over the display screen by reflecting image light from the first intermediate image on the display screen;
Equipped with
The variable projection optical system according to claim 1, wherein the second projection optical system includes a variable focus optical system that changes a display position of the virtual image. The variable focus optical system has at least one variable focus lens,
The variable magnification projection optical system according to claim 1, wherein the variable focus lens changes a lens curvature by using any one of an elastic body and a liquid to change a display position of a virtual image.   The variable focus optical system moves at least one lens in one of an optical axis direction, a vertical direction in a plane perpendicular to the optical axis, and a combined direction of the optical axis direction and the vertical direction. The variable power projection optical system according to 1.   The variable magnification projection optical system according to claim 1, further comprising an intermediate screen at a position of the first intermediate image between the first projection optical system and the second projection optical system.   The variable magnification projection optical system according to claim 4, wherein the intermediate screen is a diffusion plate.   The variable magnification projection optical system according to claim 4, wherein the intermediate screen is a microlens array. The second projection optical system includes a relay optical system for relaying the first intermediate image, and a third projection optical system disposed on the display screen side of the relay optical system.
The variable magnification projection optical system according to claim 1, wherein a second intermediate image is formed between the relay optical system and the third projection optical system.   The variable magnification projection optical system according to claim 7, wherein the variable focus optical system is disposed in the relay optical system. The magnification change according to any one of claims 7 and 8, wherein the following conditional expression is satisfied, where β2L is the magnification of the relay optical system when the display position of the virtual image is farthest in the relay optical system. Projection optics.
0.75 <β2L <2.0 (1)   An image display apparatus equipped with the variable magnification projection optical system according to any one of claims 1 to 9.

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