CAMERA VIEWFINDER

Abstract

A camera viewfinder comprises an electronic display apparatus that is configured for the display of images that are recorded by an image sensor of an electronic camera. The camera viewfinder further comprises two mirrors for reflecting the images displayed by the display apparatus, of which at least one mirror is a free-form surface mirror whose reflective surface is formed as a free-form surface that does not have any continuous translation symmetry or rotational symmetry. At least one of the free-form surface mirrors is adjustable to at least partially compensate a vision defect of a user.

Claims

1. A camera viewfinder (10) comprising an electronic display apparatus (12) that is configured for the display of images that are recorded by an image sensor of an electronic camera; and at least two mirrors (20, 22, 24) for reflecting the images displayed by the display apparatus (12), of which at least one mirror is a free-form surface mirror (20, 22, 24) whose reflective surface is formed as a free-form surface that has no continuous translation symmetry or rotational symmetry, wherein at least one of the free-form surface mirrors (20, 22, 24) is adjustable to at least partially compensate a vision defect of a user.

2. A camera viewfinder (10) in accordance with claim 1, wherein the at least one adjustable free-form surface mirror (20, 22, 24) can be tilted about at least one axis.

3. A camera viewfinder (10) in accordance with claim 2, wherein the at least one adjustable free-form surface mirror (20, 22, 24) is configured to at least partially compensate a field-constant astigmatism of the user by the tilting about the at least one axis.

4. A camera viewfinder (10) in accordance with claim 1, wherein the at least one adjustable free-form surface mirror (20, 22, 24) is movable in a translatory manner in at least one spatial direction.

5. A camera viewfinder (10) in accordance with claim 1, wherein the at least one adjustable free-form surface mirror (20, 22, 24) is tiltable about at least one axis and is movable in a translatory manner in at least one spatial direction.

6. A camera viewfinder (10) in accordance with claim 1, wherein the at least one adjustable free-form surface mirror (20, 22, 24) is adjustable by at least two different degrees of freedom.

7. A camera viewfinder (10) in accordance with claim 1, wherein the camera viewfinder (10) has at least two adjustable free-form surface mirrors that are adjustable in different degrees of freedom.

8. A camera viewfinder (10) in accordance with claim 1, wherein the free-form surface of the adjustable free-form surface mirror (20, 22, 24) is configured such that an adjustment of this free-form surface mirror (20, 22, 24) generates an astigmatism as at least substantially the only aberration.

9. A camera viewfinder (10) in accordance with claim 1, wherein the at least one adjustable free-form surface mirror (20, 22, 24) is formed from plastic and has a reflective metal coating.

10. A camera viewfinder (10) in accordance with claim 1, wherein a lens arrangement with variable focal length is provided in the optical path of the camera viewfinder (10) for the correction of a refractive vision defect of the user.

11. A camera viewfinder (10) in accordance with claim 10, wherein the lens arrangement comprises a pair of mutually displaceable Alvarez lenses.

12. A camera viewfinder (10) in accordance with claim 10, wherein the lens arrangement comprises at least one lens having a variable radius of curvature.

13. A camera viewfinder (10) in accordance with claim 1, furthermore comprising at least one electrically controllable actuator (30, 32) that is configured to adjust the at least one adjustable free-form surface mirror (20, 22, 24).

14. A camera viewfinder (10) in accordance with claim 1, furthermore comprising a light source; a control and evaluation device (44) that is configured to activate the light source to generate a punctiform light spot on the retina of the eye of the user; and an optoelectronic receiver apparatus (42) connected to the control and evaluation device (44) for receiving light scattered back from the eye, with the control and evaluation device (44) being configured to determine a degree of a vision defect of the user on the basis of the received light.

15. A camera viewfinder (10) in accordance with claim 14, wherein the electronic display apparatus (12) has a two-dimensional matrix of light-emitting display elements; and wherein the light source comprises at least one display element of the display apparatus (12).

16. A camera viewfinder (10) in accordance with claim 14, wherein the camera viewfinder (10) has at least one electrically controllable actuator (30, 32) that is configured to adjust the at least one adjustable free-form surface mirror (20, 22, 24); and wherein the control and evaluation device (44) is configured to transmit a control command to the actuator (30, 32) on the basis of the determined degree of the vision defect of the user to adjust the at least one adjustable free-form surface mirror (20, 22, 24) such that the determined vision defect is at least partially adjusted.

17. A camera viewfinder (10) in accordance with claim 16, wherein the camera viewfinder (10) has a storage device that is connected to the control and evaluation device (44) and that is configured to store user-specific data records, with the control and evaluation device (44) being configured to control the actuator (30, 32) on the basis of a data record transmitted by the storage device, and with the user-specific data records representing at least one of the following: the degree of the vision defect of a respective user, or control commands to the actuator (30, 32) required to compensate the vision defect of a respective user.

18. An electronic camera comprising a camera viewfinder (10) in accordance with claim 1.

19. A camera viewfinder comprising at least: an electronic display configured for displaying an image; a first mirror that reflects the image displayed by the electronic display, and a second mirror that reflects the image displayed by the electronic display and reflected by the first mirror, wherein at least one of the first mirror and second mirror is a free-form surface mirror that has a reflective surface formed as a free-form surface that has no continuous translation symmetry or rotational symmetry, wherein at least one of a position and an orientation of the free-form surface mirror is adjustable.

Description

[0038] The invention will be described in the following with reference to embodiments and to the drawings. There are shown:

[0039] FIG. 1 a schematic representation of a camera viewfinder in accordance with the invention in accordance with a first embodiment;

[0040] FIG. 2 a schematic representation of a camera viewfinder in accordance with the invention in accordance with a second embodiment; and

[0041] FIG. 3 a schematic representation of a camera viewfinder in accordance with the invention in accordance with a third embodiment.

[0042] FIG. 1 shows a camera viewfinder 10 in accordance with the invention in accordance with a first embodiment. The camera viewfinder 10 comprises an electronic display apparatus 12 having a two-dimensional matrix of display elements, for example a so-called OLED display. The light irradiated by the display apparatus 12, that is the image displayed by the display apparatus 12, is first incident onto a first mirror 20 and is deflected by it in the direction of a second mirror 22. The light deflected by the second mirror 22 passes through an exit pupil 14 from the camera viewfinder 10 and can there pass into the eye of a user (not shown). Both mirrors 20, 22 have imaging properties, wherein one of the mirrors, preferably both mirrors 20, 22 are preferably configured as free-form surface mirrors. The reflective surface of the mirrors 20, 22 can be described, for example, by Zernike polynomials.

[0043] Each mirror 20, 22 is coupled to an actuator 30 and 32 respectively. The first mirror 20 can be tilted about a first axis with the aid of the actuator 30 and the second mirror 22 can be tilted about a second axis by means of the actuator 32, wherein the two axes preferably extend orthogonally with respect to one another. Manual adjustment apparatus can also be provided instead of the actuators 30, 32.

[0044] The astigmatism changes in a direction predefined by the respective tilt axis by a tilt of the mirrors 20, 22. A degree of astigmatism that is suitable to compensate an astigmatism present in the eye of the user completely or at least to a large extent can be added to the optical path of the camera viewfinder 10 by a suitable selection of the respective tilt angles.

[0045] FIG. 2 shows a camera viewfinder 110 in accordance with a second embodiment. The camera viewfinder 110 substantially corresponds to features of the camera viewfinder 10 (FIG. 1) so that the same elements or similar elements are provided with the same reference numerals. In addition to a first and second mirror 20, 22, a third mirror 24 is provided that likewise has imaging properties and can in particular be configured as a free-form surface mirror. The third mirror 24 is provided in the optical path between the second mirror 22 and the exit pupil 14.

[0046] In accordance with a modification, further mirrors, for example a total of four or five mirrors, can also be provided. All of these mirrors do not necessarily have to be configured as free-form surface mirrors; for example, spherical or planar mirrors can also be used for the beam shaping and/or beam deflection to ensure an ideal imaging quality and/or to achieve a construction shape of the camera viewfinder that is as compact as possible.

[0047] In accordance with a further modification, actuators 30, 32 can also be used that effect a change of the astigmatism by means of a displacement of the respective mirror 20, 22 on a use of a suitable free-form surface Such a displacement of one or more mirrors 20, 22 can in particular also be used to effect a focusing or defocusing.

[0048] In accordance with yet a further modification, instead of two mirrors 20, 22 that are each adjustable in one degree of freedom, a single mirror configured as a free-form surface mirror can be connected to an actuator that can adjust this mirror using two degrees of freedom. For example, these two degrees of freedom can correspond to a tilt of the mirror about two mutually orthogonal axes.

[0049] It must be noted for reasons of completeness that the arrangements of the two mirrors 20, 22 (FIG. 1) or of the three mirrors 20, 22, 24 (FIG. 2) are purely by way of example. In particular the angles and distances between the display apparatus 12, the mirrors 20, 22, 24 and the exit pupil 14 as well as the imaging properties of the mirrors 20, 22, 24 can thus be varied as desired. The sequence of adjustable and fixed-position mirrors and of conventional mirrors and free-form surface mirrors within the arrangement can also vary in the embodiments shown and in further modifications. Unwanted aberrations such as distortion or coma can be minimized and unwanted scattered light can be avoided by a selection of a suitable configuration.

[0050] A camera viewfinder 210 in accordance with a third embodiment shown in FIG. 3 substantially corresponds to the camera viewfinder 110 of FIG. 2. The camera viewfinder 210 additionally comprises a control and evaluation device 44 that is connected to the display apparatus 12, to the actuators 30, 32, and to an optoelectronic receiver apparatus 42 to communicate therewith and in particular to transmit control commands.

[0051] The receiver apparatus 42 is configured or determining aberrations and is in particular used to determine a vision defect of the user. The receiver apparatus 42 can, for example, be configured as a wavefront sensor, in particular as a so-called Shack-Hartmann sensor, and can comprise an image sensor having a lens matrix connected in front of it, wherein the lens matrix produces images of the light spot on the image sensor. Existing aberrations can be determined on the basis of deviations of the positions of the light spot images from ideal positions that apply to an optical path without aberrations.

[0052] The control and evaluation device 44 can control the display apparatus 12 such that one or more mutually adjacent display elements of the display apparatus 12 are activated, while the display elements arranged in the vicinity for this purpose at least remain substantially dark such that the activated display element(s) form(s) a point light source. A punctiform light sport can hereby be produced on the retina of the eye of a user looking into the camera viewfinder 210—without the necessity of a separate light source. Light scattered back from the eye is directed to the receiver apparatus 42 by means of a partially transmitting mirror 40 that is arranged between the exit pupil 14 and the third mirror 24 and that can be located in the optical path temporarily for the carrying out of the determination of the vision defect or permanently. The control and evaluation device 44 is configured to determine the degree of a vision defect of the user, in particular astigmatism, on the basis of the received light and in particular on the basis of the detected form of the wavefront scattered back.

[0053] The control and evaluation device 44 generates corresponding control commands for the actuators 30, 32 on the basis of the determined degree of the vision defect, said control commands having the effect that the determined vision defect is at least largely compensated by a corresponding adjustment of the mirrors 20, 22, coupled to the actuators 30, 32. The degree of the vision defect determined for a user or the corresponding control commands for the actuators 30, 32 can optionally be stored in a non-volatile memory of the control and evaluation device 44 (not shown) and are hereby available fast for a later invocation.

REFERENCE NUMERAL LIST

[0054] 10, 110, 210 camera viewfinder [0055] 12 display apparatus [0056] 14 exit pupil [0057] 20, 22, 24 mirror [0058] 30, 32 actuator [0059] 40 partially transmitting mirror [0060] 42 receiver apparatus [0061] 44 control and evaluation device