Scheimpflug camera

Abstract

The invention relates to a Scheimpflug camera (10), comprising: - a camera holder (16) for holding a camera (12); - a camera (12) which is held in the camera holder (16) and has a cylindrical sensor carrier (121), the cylinder axis of said sensor carrier defining a first optical axis, the rear end face (121) of said sensor carrier bearing an electronic interface (125) to a set of camera electronics (126) arranged in the interior of the sensor carrier (121), and a sensor (123) being fixed on the front end face (122) of said sensor carrier in a central position and in an orientation normal to the first optical axis; - a objective lens carrier for fixedly holding an objective lens which defines a second optical axis; - a pivot axis carrier (18) which bears articulation means by which the camera holder (16) is articulated on the pivot axis carrier (18), pivotably about a pivot axis (30) intersecting the first optical axis in the sensor plane, in such a way that, depending on the pivot position, the first and the second optical axis extend coaxially with respect to one another or intersect one another in the sensor plane; - and a mounting base (20), the pivot axis carrier (18) being supported so as to be rotatable relative to said mounting base about the second optical axis; wherein the camera holder (16) has a central, circular through-opening in which the sensor carrier (121) is directly supported axially fixedly and rotatably about its cylinder axis. The invention is characterized in that the pivot axis carrier (18) is supported, rotatably about the second optical axis, on the objective lens carrier which is fixedly connected to the mounting base (20).

Description

[0001] Applicant: LaVision GmbH

[0002] Lawyer's file: P-LVG 044 WO

[0003] Scheimpflug camera

[0004] Description

[0005] Field of invention

[0006] The invention relates to a Scheimpflug camera comprising

[0007] - a camera mount for holding a camera,

[0008] - a camera held in the camera holder, which has a cylindrical sensor carrier, the axis of which defines a first optical axis, the rear end face of which carries an electronic interface to camera electronics arranged inside the sensor carrier, and on the front end face of which a sensor is fixed in a central position and in an orientation normal to the first optical axis,

[0009] - a lens holder for the fixed mounting of a lens that defines a second optical axis,

[0010] - a pivot axis carrier which carries linkage means by means of which the camera holder is pivotably mounted on the pivot axis carrier about a pivot axis intersecting the first optical axis in the sensor plane, such that the first and second optical axes run coaxially to each other or intersect each other in the sensor plane, depending on the pivot position, as well as

[0011] - a mounting base, relative to which the swivel axis carrier is rotatably mounted about the second optical axis, wherein the camera holder has a central, circular through-opening in which the sensor carrier is directly mounted axially fixed and rotatably about its cylinder axis.

[0012] State of the art

[0013] Such a Scheimpflug camera is described in the still unpublished international patent application PCT / EP 2024 / 071030. The so-called Scheimpflug criterion for the sharp imaging of an object plane onto a tilted image plane defined by the sensor area of ​​the camera's image sensor is known to consist of the fact that the object plane, the image plane, and the principal optical plane of the lens, by means of which the imaging is performed, intersect in a common line. A variety of so-called Scheimpflug adapters are known, which can be placed between the camera housing and the lens and offer a wide range of mechanisms for tilting the lens (and thus its principal plane) relative to the sensor plane of the camera's image sensor. For example, DE 102004 008 072 B3 and DE 102016 121 646 B3 disclose such Scheimpflug adapters.Many of these adapters are difficult to use and, above all, have the disadvantage of increasing the working distance between the image sensor and the lens, making them incompatible with lenses that have a short working distance. This is especially true for so-called C-mount lenses with a typical working distance of 17.5 mm. However, such lenses are frequently used in industrial and metrological applications. In these situations, the object plane and camera position are often predetermined by structural constraints, making it impossible to guarantee parallel alignment of the object and sensor planes.In such cases, the optical axis of the lens is usually fixed relative to the object plane, and the required camera angle resulting from the relative position of the object plane and the lens's principal plane is set using the Scheimpflug adapter, whose lens mount is connected to the lens and whose camera mount is connected to the camera. When the camera angle is adjusted, the area projected onto the image sensor should ideally remain unchanged.

[0014] German patent DE 10 2006 046 586 B4 already discloses a user-friendly Scheimpflug adapter that complies with these specifications and can be built sufficiently compactly to accommodate lenses with short working distances. However, a disadvantage is the mechanically complex design of the camera connection, which must be rotatably mounted in a swiveling part of the adapter housing and also provide its own mechanical interface for the fixed mounting of a separate camera. Particularly in industrial applications, such as production monitoring, where only a one-time, but permanent, installation of such a Scheimpflug camera (consisting of the Scheimpflug adapter and the camera itself) is required, necessitating only occasional readjustments during its service life, this complexity translates into unnecessary costs.

[0015] In the aforementioned PCT / EP 2024 / 071030, this is addressed by proposing a specially shaped camera, housed directly within the casing of what would then no longer be considered an "adapter," instead of a separate camera mount designed for a previously "conventional" camera and a separate previously "conventional" camera. In other words, an integrated system consisting of a camera and Scheimpflug joint has been proposed, requiring only the addition of a lens to function.

[0016] This Scheimpflug camera can also be further improved, particularly with regard to its installation space and the possibilities for connecting additional components or integrating the Scheimpflug camera into more complex systems. The fact that changing the lens always involves applying force to the mechanism for adjusting the Scheimpflug criterion, meaning that readjustment should be carried out after each lens change as a precaution, must also be considered a disadvantage.

[0017] Task

[0018] The object of the present invention is to provide an improved Scheimpflug camera in this sense.

[0019] Description of the invention

[0020] This problem is solved in conjunction with the features of the preamble of claim 1 by the fact that the pivot axis carrier is rotatably mounted on the lens carrier which is fixedly connected to the mounting base about the second optical axis.

[0021] Preferred embodiments are the subject of the dependent claims. The invention is based on the trivial finding that the rotation of a lens about its lens axis, i.e., about its optical axis referred to here as the second optical axis, has no effect whatsoever on its imaging behavior. From this finding, the inventor concluded that it is not necessary to make the lens rotatable about the lens axis together with the rest of the Scheimpflug camera relative to the mounting base. Rather, it is sufficient to make only said rest rotatable relative to the lens and mounting base. According to the invention, therefore, the lens is fixed relative to the mounting base.The lens mount is permanently attached to, or even integrally formed with, the mounting base, and only a separate pivot axis carrier is required for the rotatable and pivotable coupling of the camera holder and camera to the mounting base. According to the invention, the function of holding the lens is thus transferred from the element that also fulfills the function of the pivot axis carrier to the element that also fulfills the function of the mounting base. This makes changing the lens considerably easier and possible without exerting force on the mechanism for adjusting the Scheimpflug criterion.

[0022] Preferably, the mounting base comprises a mounting base ring and a mounting base foot, the mounting base ring having a lens interface for fixing the lens. With its lens interface, the mounting base ring essentially fulfills the function of a lens carrier. In conjunction with the mounting base foot, on which it can preferably and in particular be adjustably mounted by means of a lockable ball joint, it essentially fulfills the function of an actual mounting base. By fixing the mounting base, in particular by fixing the mounting base foot to a base and subsequently adjusting the mounting base ring relative to the mounting base foot, the position and orientation of the lens, and thus its relative orientation to the plane of the object to be imaged, is predetermined. The lens carrier, or...The lens interface of the mounting base ring preferably conforms to the C-mount standard. However, if lenses with a larger working distance are to be used, a mounting base ring with a correspondingly axially dimensioned attachment can be used, which then carries a suitable mechanical lens interface for the selected lens. The pivot axis carrier of the Scheimpflug camera according to the invention is preferably designed as a base ring with axially rearward projecting support elements to which the camera holder is hinged. In order to enable the generally known pivoting movement of the sensor relative to the lens, the support elements can be designed as two axially rearward-directed tabs arranged at opposite positions on the base ring. At least one of these can be provided with a radially oriented axis channel into which a corresponding axis pin of the camera holder projects.Alternatively, it can be provided with a radially inward-facing axle pin that projects into a corresponding axle channel of the camera holder. A person skilled in the art will understand that both support elements can be identical or—in particular, each in one of the ways described—different. In any case, it can be provided that each axle pin is designed as a ball head or ball-head pin spring-loaded towards the associated axle channel. This considerably simplifies assembly. However, screwing in the axle pins is also conceivable.

[0023] To ensure the required rotational degree of freedom between the pivot axis carrier and the mounting base, it is preferably provided that the base ring is supported on an inner circumference by means of a radial bearing designed as a rolling or sliding bearing on an outer circumference of the mounting base ring. This design is particularly short axially, since the base ring of the pivot axis carrier can lie in the same plane as the mounting base ring. The reverse design, in which the base ring is supported on an outer circumference by means of a radial bearing designed as a rolling or sliding bearing on an inner circumference of the mounting base ring, is also possible.

[0024] A functionally equivalent but axially longer design provides that the base ring of the pivot axis carrier has a coaxial annular groove in its front end face, into which a corresponding bearing ring web of the mounting carrier ring or a plurality of corresponding bearing journals distributed around its circumference engage. Alternatively, the base ring of the pivot axis carrier can have a coaxial bearing ring web or a plurality of axially extended bearing journals distributed around its circumference in its front end face, which engage in a corresponding annular groove in the rear end face of the mounting carrier ring. Further details and advantages of the invention will become apparent from the following detailed description and the drawings.

[0025] Brief description of the drawings

[0026] They show:

[0027] Figure 1: an exploded view of an embodiment of a Scheimpflug camera according to the invention,

[0028] Figure 2: a cross-sectional view of the Scheimpflug camera of Figures 1 and 2,

[0029] Figure 3: a sectional view of an alternative embodiment and

[0030] Figure 4: a sectional view of another alternative embodiment.

[0031] Description of preferred embodiments

[0032] Identical reference symbols in the figures indicate identical or analogous elements.

[0033] Figures 1 and 2 show, in different views, a preferred embodiment of a Scheimpflug camera 10 according to the invention. Figures 3 and 4 show alternative, also preferred embodiments of a Scheimpflug camera 10 according to the invention. These will be discussed together below, unless reference is made to a specific figure.

[0034] In the illustrated embodiments, the Scheimpflug camera 10 comprises the actual camera 12, which, according to the invention, has a cylindrical sensor carrier 121 on the front end face 122 of which an image sensor 123, for example a CCD or CMOS sensor, is arranged. On its rear end face 124, visible in Figures 2 to 4, various electronic interfaces, collectively referred to as an electronic interface 125, are arranged. These interfaces are connected to camera electronics 126 located inside the sensor carrier 121, which in turn are connected to the sensor 123. The sensor carrier 121 is rotatably mounted in a hollow cylindrical camera holder 16 via a radial bearing 14, indicated in Figures 2 to 4. This radial bearing can be designed as a rolling bearing, but preferably as a sliding bearing.Since both the sensor 123 and the camera electronics 126 and the electronic interfaces 125 are fixed to the sensor carrier 121, rotational mobility by any angle of rotation is guaranteed.

[0035] In the illustrated embodiments, the hollow cylindrical camera holder 16 has two radially outwardly projecting axle pins 161 at opposite positions in the region of its front end. The axle pins 161 are positioned such that their common axis lies within the sensor surface of the sensor 123.

[0036] The pivot pins 161 each project through an axle channel 183, which is provided in an axially rearward extending tab 182 of a pivot axis carrier 18 that is otherwise arranged axially in front of the camera holder 16. In the illustrated embodiment, the pivot axis carrier 18 essentially consists of a base ring 181 to which the aforementioned tabs 182 with their axle channels 183 are fixed. The pivot pins 161 of the camera holder 16, together with the axle channels 183 of the pivot axis carrier 18, form a pivot axis 30 extending through the sensor plane of the sensor 123, about which the camera holder 16 (and with it the camera 12) can be pivoted relative to the pivot axis carrier 18.

[0037] In its front end face 184, the base ring 181, in the embodiment shown in Figures 1 and 2, has an annular groove 185. A bearing ring web 203, i.e., an annular web serving as a bearing, of a mounting base 20 projects into this annular groove 185. The bearing ring web 203 projects axially rearward from a mounting base ring 202, which, together with a mounting base foot 201, forms the mounting base 20. The bearing ring web 203, together with the annular groove 185 into which it projects, forms a pivot bearing for the swivel axis carrier 18 (and with it for the camera holder 16 and the camera 12 mounted therein). The mounting base foot 201 serves to fix the entire slurry plow camera 10 in a larger measuring apparatus. The inner surface of the mounting base ring 202 has a lens interface 204, which may be designed in particular as a thread, for example according to the C-mount standard, for screwing in a lens.It is also conceivable that instead of the lens, an attachment not shown in the figures is screwed in as an adapter for lenses of other standards and working distances.

[0038] In summary, the highly compact Scheimpflug camera 10 according to the invention offers the following adjustment options: The lens is fixed to the mounting base 20, in particular at the lens interface 204 of the mounting base ring 202. The pivot axis carrier 18 is rotatable relative to the mounting base 20 about the optical axis defined by the mounting base ring 202 or by the lens. The camera holder 16 is pivotable about a pivot axis 30 extending through the sensor plane of the sensor 123. This pivot axis 30 is rotatable with the pivot axis carrier 18 relative to the mounting base 20 and intersects an optical axis of the camera 12 in the sensor plane, defined by the central surface normal of the sensor 123. The camera 12 is, in turn, rotatable about this optical axis of the camera 12 relative to the camera holder 16.

[0039] The embodiments shown in Figures 3 and 4 differ from those shown in Figures 1 and 2 in the specific type of rotary bearing arrangement of the pivot axis carrier 18 relative to the mounting base 20. Here, the base ring 181 of the pivot axis carrier 18 and the mounting base ring 202 lie in the same plane or overlap each other at least axially in a common plane. In this common plane, they are rotaryally supported relative to each other by means of a radial bearing 22. The radial bearing 22 can be designed as a rolling or sliding bearing. In the embodiment shown in Figure 3, the radial bearing 22 couples the inner surface of the base ring 181 with the outer surface of the mounting base ring 202. In the embodiment shown in Figure 4, these relationships are reversed.

[0040] Naturally, the embodiments discussed in the detailed description and shown in the figures represent only illustrative examples of the present invention. A wide range of possible variations is available to those skilled in the art in light of this disclosure. Reference numerals

[0041] 10 Scheimpflug cameras

[0042] 12 Camera

[0043] 121 sensor carriers

[0044] 122 front face of 121

[0045] 123 Sensor

[0046] 124 rear frontal area of ​​121

[0047] 125 Electronic interface

[0048] 126 Camera electronics

[0049] 14 swivel bearings

[0050] 16 camera holders

[0051] 161 axle stubs

[0052] 18 swivel axle carriers

[0053] 181 Base ring

[0054] 182 tab

[0055] 183 axle channel

[0056] 184 front face of 181

[0057] 185 Ring groove

[0058] 20 mounting bases

[0059] 201 Mounting base foot

[0060] 202 Mounting base ring

[0061] 203 Bearing ring bridge

[0062] 204 Lens interface

[0063] 22 radial bearings

[0064] 30 Swivel axis

Claims

Patent claims 1. Scheimpflug camera (10), comprehensive - a camera holder (16) for mounting a camera (12), - a camera (12) mounted in the camera holder (16), which has a cylindrical sensor carrier (121) whose cylindrical axis defines a first optical axis, whose rear end face (121) carries an electronic interface (125) to a camera electronics (126) arranged inside the sensor carrier (121) and on whose front end face (122) a sensor (123) is fixed in a central position and in an orientation normal to the first optical axis, - a lens holder for the fixed mounting of a lens that defines a second optical axis, - a pivot axis carrier (18) which carries linkage means by means of which the camera holder (16) can be pivoted about a pivot axis (30) intersecting the first optical axis in the sensor plane on the The pivot axis carrier (18) is articulated such that the first and second optical axes run coaxially to each other or intersect each other in the sensor plane, depending on the pivot position, as well as - a mounting base (20) relative to which the pivot axis carrier (18) is rotatably mounted about the second optical axis, wherein the camera holder (16) has a central, circular through-opening in which the sensor carrier (121) is directly mounted axially fixed and rotatable about its cylindrical axis, characterized in that the pivot axis carrier (18) is rotatably mounted about the second optical axis on the lens carrier which is fixedly connected to the mounting base (20).

2. Scheimpflug camera (10) according to claim 1 , characterized in that the mounting base (20) has a mounting base ring (202) and mounting base foot (201), wherein the mounting base ring (202) has a lens interface (204) for fixing the lens.

3. Scheimpflug camera (10) according to claim 2, characterized in that the lens interface (204) conforms to the C-mount standard.

4. Scheimpflug camera (10) according to one of claims 2 to 3, characterized in that the mounting base ring is adjustably mounted relative to the mounting base foot by means of a lockable ball joint.

5. Scheimpflug camera (10) according to one of claims 2 to 4, characterized in that the pivot axis carrier (18) is designed as a base ring (181) with axially rearward projecting support elements to which the camera holder (16) is articulated.

6. Scheimpflug camera (10) according to claim 5, characterized in that the base ring (181) is mounted on an inner circumference by means of a radial bearing (22) designed as a rolling or sliding bearing on an outer circumference of the mounting base ring (202).

7. Scheimpflug camera (10) according to claim 5, characterized in that the base ring (181) is mounted on an outer circumference by means of a radial bearing (22) designed as a rolling or sliding bearing on an inner circumference of the mounting base ring (202).

8. Scheimpflug camera (10) according to claim 5, characterized in that the base ring (181) has a front end face (184) - either has a coaxial ring groove (185) into which a corresponding bearing ring web (203) of the mounting support ring (20) engages or a plurality of corresponding bearing journals distributed around its circumference, - or has a coaxial bearing ring web or a plurality of axially extended bearing journals distributed around its circumference, which engage in a corresponding annular groove in the rear end face of the mounting support ring.

9. Scheimpflug camera (10) according to one of claims 5 to 8, characterized in that the support elements are designed as two axially rearward directed tabs (182) arranged at opposite positions of the base ring, at least one of which - either with a radially oriented axis channel (183) into which a corresponding axis pin (161) of the camera holder (16) projects, - or is provided with a radially inward-facing axle pin that projects into a corresponding axle channel of the camera holder.

10. Scheimpflug camera according to claim 9, characterized in that each axle pin (161) is designed as a ball head or ball head pin spring-loaded towards the associated axle channel (183).

Images